Seoul, South Korea
Seoul, South Korea

Konkuk University is a private university located in Seoul and Chungju. The Seoul campus is located in the southeastern part of Seoul, near the Han River, and is served by a metro station of the same name. The university possesses accreditation from the South Korean Ministry of Culture and Education. The university emphasizes technology and science majors and research. Wikipedia.


Time filter

Source Type

Disclosed are a nanopipette provided with a membrane containing a saturated ion-sensitive material, a method for preparing the same, and an ion measuring apparatus comprising the same.


Patent
Konkuk University and KR Biotech Co. | Date: 2017-02-15

The present invention relates to an anti-influenza virus composition containing a Poncirus trifoliata extract as an active ingredient. The composition of the present invention inhibits influenza virus replication and infection, thereby exhibiting excellent effects in the prevention and treatment of influenza virus infection. The present invention provides a composition for preventing, treating, or alleviating diseases caused by influenza virus.


Chang I.,University of New South Wales | Im J.,Korea Advanced Institute of Science and Technology | Lee S.-W.,Konkuk University | Cho G.-C.,Korea Advanced Institute of Science and Technology
Construction and Building Materials | Year: 2017

Various biological approaches recently have been explored as alternative environmentally-friendly soil improvement strategies in the fields of construction and geotechnical engineering, with the aim of reducing the use of high greenhouse gas emitting construction binders such as cement. Previous studies have shown the effectiveness of microbial biopolymers in soil improvement. However, there are still concerns about the durability and serviceability of biopolymer treated soils, resulting from the biodegradation and hydrolysis behaviors of the biologically produced compounds. In this study, the strength and durability of gellan gum biopolymer treated Jumunjin sand (standard sand of the Republic of Korea) was evaluated under cyclic wetting and drying. The results obtained indicate that the cyclic wetting and drying of gellan gum-treated sands results in a gradual degradation of strength, due to the dissociation of the gellan gum monomers under wetting and imperfect recomposition during re-drying, with an approximately 30% strength reduction over 10 cycles. However, a certain degree of strength recovery and resistance was observed even after numerous cycles, indicating that gellan gum-treated soils can potentially be applied for temporary or medium-term purposes in practical construction. © 2017 Elsevier Ltd


Lee B.H.,Konkuk University | Cho J.W.,Konkuk University | Kim K.H.,Shinshu University
European Polymer Journal | Year: 2017

Polypropylene (PP)/multi-walled carbon nanotube (MWCNT) fibers at MWCNT contents of 0, 0.5 and 1 wt% were melt spun and photothermally drawn by irradiating them with a near-infrared laser during elongation. These fibers were then compared to hot-drawn PP/MWCNT fibers. The crystallinity of the photothermally drawn PP/MWCNT fibers was higher, whereas the degree of orientation of PP crystals was similar for both types of fibers. However, the degree of orientation of MWCNTs in the photothermally drawn PP/MWCNT fibers was higher, which was ascribed to the laser-induced local heating effect of MWCNTs dispersed in the polymer matrices. Higher breaking stress and modulus were obtained for the photothermally drawn PP/MWCNT fibers at the same MWCNT content. Therefore, laser-induced photothermal drawing has significant potential as a fiber-drawing method for enhancing the mechanical properties of the PP/MWCNT fibers. © 2017 Elsevier Ltd


Jang S.H.,University of Seoul | Kim Y.-W.,University of Seoul | Kim K.J.,Konkuk University
Journal of the European Ceramic Society | Year: 2017

SiC-Zr2CN composites were fabricated from β-SiC and ZrN powders with 2 vol% equimolar Y2O3-Sc2O3 additives via conventional hot pressing at 2000 °C for 3 h in a nitrogen atmosphere. The electrical and thermal properties of the SiC-Zr2CN composites were investigated as a function of initial ZrN content. Relative densities above 98% were obtained for all samples. The electrical conductivity of Zr2CN composites increased continuously from 3.8 × 103 (Ωm)−1 to 2.3 × 105 (Ωm)−1 with increasing ZrN content from 0 to 35 vol%. In contrast, the thermal conductivity of the composites decreased from 200 W/mK to 81 W/mK with increasing ZrN content from 0 to 35 vol%. Typical electrical and thermal conductivity values of the SiC-Zr2CN composites fabricated from a SiC-10 vol% ZrN mixture were 2.6 × 104 (Ωm)−1 and 168 W/m K, respectively. © 2016 Elsevier Ltd


Sohn K.,Konkuk University
Human Fertility | Year: 2017

While scholars and policymakers have investigated the causes and consequences of low fertility, they have neglected a related issue: advanced parental age. This is an important issue because advanced parental age adversely affects babies in the short and long run. South Korea recently topped the list of low-fertility countries, and so this study examined the trends in parental age in this country. We analysed all births between 1997 and 2014, the census for 2000 and 2010, and aggregate marriage data to report the trends in age at first marriage, interval from marriage to first birth, and parental age at first birth and at all births. At every stage, age increased rapidly for both parents. As a result, of babies born to fathers aged 20–54, 20.2% were born to fathers aged 35–54 in 2000 with the proportion increasing to 38.7% in 2010 – almost double in a single decade. The corresponding figures for mothers increased from 6.7% to 17.2% – more than double. Potential parents and policymakers can use this information to time births more appropriately, thereby reducing risks to babies and mothers. © 2017 The British Fertility Society


Hwang D.,Konkuk University | Hwang K.C.,Sungkyunkwan University | Kim D.I.,Konkuk University | Lee T.-J.,Konkuk University
IEEE Transactions on Wireless Communications | Year: 2017

We investigate self-energy recycling (S-ER)-based RF powered multi-antenna relay channels (RCs) for the coverage extension in sensor networks or small cells. In the S-ER-based RF powered RC, the power used at the relay station for data transmission depends only on the energy from the access point and the recycled energy from its own transmission. We propose an optimal beamforming scheme with associated protocols and study their behaviors for both cases of downlink only and joint up-down link. Strategies for the power allocation between data transmission and RF powering are provided and a comparison with the conventional RF powered RC is made. For the proposed power allocation strategies, the performance of the conventional RC is achieved by the proposed RF powered RC only when infinite RF power is available. A high value of S-ER helps the proposed systems to reach the performance of conventional relay systems. In the joint up-down link protocol, we show that the up-down rate region can simply be constructed with easy power allocation strategy. © 2016 IEEE.


Lee S.J.,Konkuk University | Yoon S.T.,Konkuk University
CiOS Clinics in Orthopedic Surgery | Year: 2017

Background: The purpose of this study was to report the ultrasonographic findings and clinical features of schwannoma of the hand. Methods: We enrolled 8 patients who were initially diagnosed with ganglion by ultrasonography but finally with schwannoma by a tissue biopsy. We retrospectively analyzed the ultrasonographic findings of eight patients including echogenicity, internal homogeneity, posterior enhancement, internal vascularity, and clinical manifestations such as the occurrence site, tenderness, Tinel’s sign, and paresthesia before the surgery. Results: The occurrence sites were as follows: two cases on the thenar area, one case on the second web space, three cases on the third web space, one case on the radiovolar aspect of the proximal phalanx of the index finger, and one case on the radiovolar aspect of the proximal phalanx of the middle finger. Four patients suffered from tenderness and pain on presentation, and all patients had pain around the mass before presentation. Tinel’s sign was present without paresthesia in one case. Ultrasonography revealed cystic lesions showing clear margins in all cases, and two of them had acoustic enhancement without internal flow. Conclusions: It may not be easy to diagnosis schwannoma of the hand with ultrasonography alone when the lesion is small because of the similarity to the ultrasonographic findings of ganglion. Therefore, it is necessary to consider the possibility of schwannoma if a mass near the digital nerve or cutaneous nerve branch is accompanied by dull pain and tenderness. © 2017 by The Korean Orthopaedic Association.


Lee H.,Konkuk University | Jo A.,Konkuk University | Kim H.C.,Konkuk University
Investigative Ophthalmology and Visual Science | Year: 2017

PURPOSE. To investigate the association of three-dimensionally quantified lesions with best-corrected visual acuity (BCVA) in typical neovascular age-related macular degeneration (nAMD). METHODS. We retrospectively analyzed 65 eyes of 61 typical nAMD patients. Lesions at baseline and month 12 were manually delineated in optical coherence tomography. The volume of intraretinal fluid (IRF), subretinal fluid (SRF), subretinal hyperreflective material (SHRM), and pigment epithelial detachment (PED) were measured. In addition, the areas of external limiting membrane (ELM) and ellipsoid zone (EZ) were calculated. RESULTS. At baseline, poor baseline BCVA was associated with increased volume of IRF and SHRM and impaired area of ELM (β = 0.34, P = 0.001; β = 0.46, P < 0.001; and β = 0.23, P = 0.03, respectively). At month 12, poor BCVA was associated with increased volume of IRF, reduced intact ELM area, and decreased EZ area (β = 0.24, P = 0.01; β = 0.30, P = 0.02; and β = 0.37, P = 0.004, respectively). Baseline BCVA, volume of IRF, and intact area of ELM were significant predictors for BCVA at month 12 (β = 0.29, P = 0.01; β = 0.30, P = 0.01; and β = 0.28, P = 0.01). Changes of BCVA were associated with changes of SHRM volume, intact EZ area, and ELM area (β = 0.35, P = 0.002; β = 0.28, P = 0.01; and β = 0.22, P = 0.048, respectively). The predictive power of volumetric analysis was higher than that of qualitative analysis (R2 = 0.47 vs. R2 = 0.37). The volume of SRF and fibrovascular PED showed positive and negative effect on visual outcome each, but they were not strong enough to remain in multivariate model. CONCLUSIONS. Best-corrected visual acuity could be explained by three-dimensional optical coherence tomography morphology to a fair degree. In addition, three-dimensional analysis could predict visual outcomes better than qualitative analysis. © 2017 The Authors.


This paper describes a dual-buck inverter (DBI) for residential photovoltaic power conversion systems. The DBI consists of unidirectional and bidirectional switching legs, which are operated at different frequencies to attain high efficiency. The operation modes of the DBI are analyzed and a third- order control model is derived based on the analysis. Since the third-order model cannot be easily handled by the current controller design, a simple first order-model is obtained with proper assumptions and manipulations. After this, a repetitive current controller using the first-order model is designed to improve the accuracy of the current regulation in both continuous and discontinuous conduction modes. Due to the universal operation of the designed repetitive controller, the tracking accuracy for a low power reference is drastically enhanced, and this significantly improves the maximum power point tracking (MPPT) ability of the PV system. In order to verify the performance of the proposed scheme, a 3-kW DBI prototype was built and tested. The experimental results demonstrate that the proposed scheme not only reduces the total harmonic distortion of the output current, but also achieves highly accurate power tracking performance with high efficiency. © 2016


PURPOSE:: To investigate the association of vessel tortuosity with severity of diabetic retinopathy (DR) using optical coherence tomography angiography. METHODS:: We retrospectively analyzed 30 healthy eyes and 121 eyes of diabetic subjects with no DR, mild nonproliferative DR (NPDR), moderate to severe NPDR and proliferative DR (PDR). Binarized images were used to quantify the vessel tortuosity, vessel density, foveal avascular zone (FAZ) area, and FAZ acircularity. The vessels were divided vertically as superficial retinal layer and deep retinal layer, and horizontally as circular areas with 3 mm and 1.5 mm diameters. Analysis of variance was performed for multiple comparisons. Correlation analysis evaluated the association between the quantified parameters. RESULTS:: Compared with healthy eyes, vessel tortuosity increased as DR severity was more in NPDR, but decreased in PDR (P = 0.033). The decrease in vessel density and the increase in both FAZ area and FAZ acircularity were consistent, while DR approached PDR. Among all parameters, statistically significant difference between no DR and mild NPDR was observed only in vessel tortuosity, especially within the 1.5 mm area of superficial retinal layer (P = 0.011). Correlations of vessel tortuosity with FAZ area and acircularity were confined to the 3 mm and 1.5 mm areas of superficial retinal layer (r = −0.185, P = 0.023 for FAZ area; r = 0.268, P = 0.001 for FAZ acircularity), while vessel density strongly correlated with FAZ parameters in the superficial retinal layer and deep retinal layer. CONCLUSION:: Vessel tortuosity increased as the stage of NPDR was more severe, but decreased in PDR. The vessel tortuosity determined using optical coherence tomography angiography might be a useful parameter indicating the progression to PDR, circumventing the risk from invasive conventional angiography. © 2017 by Ophthalmic Communications Society, Inc.


Ha N.S.,Konkuk University | Le V.T.,Konkuk University | Goo N.S.,Konkuk University
International Journal of Fatigue | Year: 2017

In this study, the fracture properties of a piezoelectric stack actuator made of a single crystal (PMN-29PT) were investigated using a three point bending test along with the digital image correlation (DIC) technique. To simplify the model of the piezoelectric stack and minimize the cost, two layers of PMN-29PT and one thin copper electrode were glued together using silver conductive adhesive instead of a real piezoelectric stack with 40PMN-29PT layers. The PMN-29PT layers were then strongly attached with a two square section acrylic beam forming a beam with the same geometry as the piezoelectric stack. The three point bending test results showed that the force at the crack onset was around 85% of the fracture force. The maximum stress and fracture energy from force-displacement data were measured to be 1.41MPa and 3.83J/m2, respectively. Furthermore, the fracture surface indicated that the fracture energy was affected by the surface of the copper electrode, and that the rough surface of the electrode can increase the fracture energy. The fracture energy was determined using a simple beam theory. The fracture energy according to the simple beam theory was slightly smaller than that from force-displacement data. Understanding the measured fracture properties of the piezoelectric stack will help us prevent the fracture of the stack when the piezoelectric stack actuator is handled. © 2017 Elsevier Ltd.


A 15 year old male who had been involved in a motor vehicle accident underwent a craniotomy for an acute EDH and a subsequent splenectomy for the splenic rupture, which was complicated by ischemia and a series of severe infection. Splenectomy was performed for concern of therapy refractory thrombocytopenia. We suggest that a thorough consideration on possible and potential complications along with a detailed description of his clinical courses and a review of the literature. © 2017 The Author


Souri A.H.,University of Houston | Choi Y.,University of Houston | Jeon W.,University of Houston | Woo J.-H.,Konkuk University | And 2 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2017

Recent regulatory policies in East Asia reduce ozone precursors, but these changes are spatially and temporally nonuniform. This study investigates variations in the long-term trends of tropospheric NO2, HCHO, and HCHO/NO2 ratios to diagnose ozone sensitivity to changes in NOx and volatile organic compound using the Ozone Monitoring Instrument (OMI). Using an adaptive-degree polynomial filter, we identify extremums of time series of NO2 to determine when and how NO2 change. Due to the regulations in China, trends which were predominantly upward turned downward. The years undergoing these changes primarily happened in 2011 and 2012. OMI column densities, however, suggest that NOx sources in South Korea, the Pearl River Delta (PRD), Taiwan, and Japan have not consistently decreased. Specifically, as Chinese exports of NO2 started subsiding, increasing trends in NO2 columns over several Korean cities, including Seoul, become evident. To quantify the changes in NOx emissions from summertime 2010 to 2014, we conduct a 3D-Var inverse modeling using a regional model with MIX-Asia inventory and estimate NOx emissions (in 2010 and 2014) for the PRD (1.6 and 1.5 Gg/d), the Yangtze River Delta (3.9 and 3.0 Gg/d), north China (15.6 and 14.3 Gg/d), South Korea (1.6 and 1.5 Gg/d), and Japan (2.7 and 2.6 Gg/d). OMI HCHO shows upward trends in East Asia resulting from anthropogenic effects; however, the magnitudes are negative in the PRD, Japan, North Korea, and Taiwan. OMI HCHO/NO2 ratios reveal that while South Korea, Japan, and the south of China have undergone toward more NOx-sensitive regime, areas around the Bohai Sea have become more NOx saturated. ©2017. American Geophysical Union. All Rights Reserved.


Kuk S.K.,Korea Advanced Institute of Science and Technology | Singh R.K.,Konkuk University | Nam D.H.,Korea Advanced Institute of Science and Technology | Singh R.,Konkuk University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2017

Natural photosynthesis is an effective route for the clean and sustainable conversion of CO2 into high-energy chemicals. Inspired by the natural process, a tandem photoelectrochemical (PEC) cell with an integrated enzyme-cascade (TPIEC) system was designed, which transfers photogenerated electrons to a multienzyme cascade for the biocatalyzed reduction of CO2 to methanol. A hematite photoanode and a bismuth ferrite photocathode were applied to fabricate the iron oxide based tandem PEC cell for visible-light-assisted regeneration of the nicotinamide cofactor (NADH). The cell utilized water as an electron donor and spontaneously regenerated NADH. To complete the TPIEC system, a superior three-dehydrogenase cascade system was employed in the cathodic part of the PEC cell. Under applied bias, the TPIEC system achieved a high methanol conversion output of 220 μm h−1, 1280 μmol g−1 h−1 using readily available solar energy and water. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim


Kim W.,Konkuk University
2016 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference, APSIPA 2016 | Year: 2016

This paper presents an overview of liveness detection particularly based on fingerprint images. Since fingerprints start to be widely employed in the mobile devices such as smartphones and tablets for payment as well as security, high-performed algorithms have been explored in literature. At the same time, such mobile systems are highly required to detect spoofing attacks by fabricated fingerprints with malicious intends. To this end, many researchers have developed liveness detection methods based on local image descriptors. In this paper, we briefly review those descriptors used for fingerprint liveness detection and compare the detection performance based on representative datasets, i.e., ATVS, LivDet2009, and LivDet2011. From experimental results, we can conclude that textural patterns of a local region in the fingerprint image have a good ability to discriminate fake fingerprints from live ones. © 2016 Asia Pacific Signal and Information Processing Association.


Ko E.,Konkuk University | Kim E.Y.,Konkuk University | Yu Y.,Konkuk University
International Conference on Intelligent User Interfaces, Proceedings IUI | Year: 2017

In this paper, we propose the selection of representative images based on human affects. For this, the images are first transformed into the affective space using convolutional neural network (CNN). Thereafter, images are clustered on affective space and then the resulting clusters are ranked based on the proposed three properties - coverage, affective coherence and distinctiveness. Finally, some representative images are selected from top-ranked clusters. The experiments conducted on Flickr images showed the effectiveness of the proposed method. Copyright is held by the owner/author(s).


Enkhtaivan G.,Konkuk University | Muthuraman P.,Konkuk University | Kim D.H.,Konkuk University
Journal of Molecular Recognition | Year: 2017

Influenza virus has had a high rate of antigenic shift and drift that causes significant morbidity and mortality in humans and animals. The lack of excellent pharmacological treatment underlines the importance of the development of the novel antiviral drugs. We investigated the anti-influenza A and B viruses of 2,4-dichlorophenoxyacetic acid (2,4-D), which is the synthetic analog to auxin and is used as a popular herbicide in the agricultural practices. 2,4-D was evaluated using a cytopathic effect reduction method; assay results showed that 2,4-D possessed strong anti-influenza A and B viruses inhibiting the formation of a visible cytopathic effect. Influenza viral RNA expression was performed by quantitative real-time polymerase chain reaction. 2,4-D also inhibited virus replication in the early stage of influenza virus infection without direct interaction with virus particles. Additionally, 2,4-D significantly inhibited various factors occur during influenza virus infection as the acidic vesicular formation and reactive oxygen species production. Moreover, 2,4-D represented no cytotoxicity in normal kidney cell. Therefore, these findings provide an understanding of the mechanism and efficient use of 2,4-D in pharmacological applications against influenza virus infection. © 2017 John Wiley & Sons, Ltd.


Nguyen H.A.D.,FLEXIBLE DISPLAY | Lee C.,Changwon National University | Shin K.-H.,Konkuk University
Robotics and Computer-Integrated Manufacturing | Year: 2017

Roll-to-roll gravure printing has recently gained considerable interest regarding its application for manufacturing printed electronics, owing to its potential for processing large areas at low costs with high throughput. The geometry of the printed lines depends mainly on the process parameters. Unfortunately, missing areas and well-defined line widths have opposite tendencies. This paper presents a multi-response optimization process for printing high-resolution conductive lines using roll-to-roll gravure printing. Our optimization is based on grey relational analysis and an analysis of variance in conjunction with the Taguchi method, which uses an orthogonal array. Together, these techniques are used to optimize the printed pattern geometry and missing areas. Furthermore, we investigate several parameters for roll-to-roll gravure printing, such as ink viscosity, printing speed, and nip pressure, and the effect of these parameters on the line width, thickness, and missing areas of the printed pattern. Experiments were conducted to evaluate the proposed method, and the results of this evaluation demonstrate an improvement to the well-defined line width, thickness, and continuity of conductive lines under optimal parameter settings using the proposed grey-based Taguchi method. © 2017 Elsevier Ltd


Mamun Kabir S.M.,Bangladesh University of Textiles | Koh J.,Konkuk University
Coloration Technology | Year: 2017

Sea-island-type, black dope-dyed poly(ethylene terephthalate) microfibre fabrics were compared with normal sea-island-type PET microfibres in terms of their thermal properties, alkaline weight reduction, and dyeing properties. A comparison of the weight reduction behaviours of the two microfibre yarns revealed that the microfibre yarn containing carbon black exhibited a higher dissolution speed than that containing no carbon black. The incorporation of carbon black particles in the polyester fibre matrix therefore accelerates the degradation of the less crystalline sea component during alkali treatment. A cationic dye staining method was used to monitor the alkaline dissolution behaviour of the sea-island-type PET microfibres, and compared with the K/S values and the colour difference, the fk value is the most-desirable indicator for determination of the termination point of the alkaline dissolution process. The colour strength and the colour fastness of the dope-dyed sea-island-type PET microfibre fabrics are superior to those of the normal type. © 2017 Society of Dyers and Colourists.


Kim E.Y.,Konkuk University
Electronics Letters | Year: 2017

A novel statistical model for real-time traffic flow prediction is proposed. In this study, a 3D Markov random field (MRF) is used to model the temporal dynamics of the traffic flow measured by VDS sensor network. Then, the spatial and temporal relations between roads at a given location are represented by the 3D graph using cliques, then its structure is determined by clique parameters. Here, a support vector regression is adopted for estimating the correlation parameters. The technique is applied to actual traffic flow data from Gyeongbu expressway, South Korea. The experiments demonstrate that the proposed method can predict the traffic flow with an accuracy of 85.6%, which improves 17.3% of the existing state-of-the-art method. © 2017 The Institution of Engineering and Technology.


Li Z.,Konkuk University | Kim S.-J.,Konkuk University
Chemical Engineering Journal | Year: 2017

This study presents a pulsatile micromixer which does not use any dynamic off-chip controllers to achieve homogeneous mixing. The micromixer system consists of oscillator and mixer units that include microfluidic valves and elastomeric membranes. The oscillator unit autonomously generates pulsatile pressure using the constant input of water head pressure. Driven by the pulsatile pressure, periodic fluidic bands are generated in the mixer unit and are mixed within a short channel length. In this way, the oscillator unit controls fluidic switching frequency and the mixer unit regulates flow rate, separately. The mixing performance for various channel widths, switching frequencies, and flow rates is analyzed. The micromixer shows homogenous mixing with a mixing index of ∼90% for a flow rate of up to 20 μL/min and switching frequency in the range of 14–20 Hz. © 2016 Elsevier B.V.


Lee S.A.,Konkuk University | Kim B.G.,Konkuk University
Journal of Animal and Plant Sciences | Year: 2017

The objectives were to develop a classification standard for copra meal (CM) and copra expellers (CE) based on ether extract (EE) concentration and to develop prediction equations for EE and gross energy (GE) concentrations in copra byproducts. Data from 520 copra byproduct samples were used. Linear broken-line and quadratic models indicated breakpoints of 6.40 and 6.22% EE concentration to effectively distinguish the two copra byproducts, respectively. The EE was negatively correlated with moisture (r = -0.611, P < 0.001) and positively correlated with GE and organic matter (OM; r > 0.56, P < 0.001). The GE concentration in the copra byproducts showed a positive correlation with OM (r = 0.524, P < 0.001). The most suitable and simple prediction equations where the components were expressed in % (as-is basis) were EE = -77.0 + 0.976 × OM with R2 = 0.439; GE, kcal/kg = 3,921 + 52.2 × EE with R2 = 0.324. In conclusion, CM and CE can be distinguished by EE of 6.31%. Organic matter can be used to estimate EE and GE in copra byproducts. © 2017, Pakistan Agricultural Scientists Forum. All rights reserved.


Hyung S.-W.,Korea Research Institute of Standards and Science | Lee C.-H.,Konkuk University | Kim B.,Korea Research Institute of Standards and Science
Food Chemistry | Year: 2017

Certified reference materials (CRMs; KRISS CRM 108-03-003, 108-03-004) were developed for the accurate determination of fluoroquinolones (enrofloxacin and ciprofloxacin, respectively) in chicken meat. Two groups of chickens were cured with feeds containing enrofloxacin and ciprofloxacin, respectively. After slaughter, the thigh and breast meats were combined for the respective groups and the meat was freeze-dried, pulverized, sieved, and V-mixed. The final bulk material was bottled in 10 g portions. For certification of the CRMs, isotope dilution-liquid chromatography/tandem mass spectrometry was used. The certified values of the CRMs were (19.06 ± 0.86) mg/kg for enrofloxacin and (1.095 ± 0.038) mg/kg for ciprofloxacin. The stabilities of the CRMs were monitored at −70 °C for 12 months, at −20 °C for 2 months, and at room temperature for 1 month. Both CRM candidates were stable during the monitoring period for each temperature. © 2017


Cheung K.,National Center for Theoretical science | Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Okada H.,National Center for Theoretical science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2017

We propose a three-loop neutrino mass model with a few leptoquark scalars in SU(2)L-triplet form, through which we can explain the anomaly of B→K(⁎)μ+μ−, a sizable muon g−2 and a bosonic dark matter candidate, and at the same time satisfying all the constraints from lepton flavor violations. We perform global numerical analyses and show the allowed regions, in which we find somewhat restricted parameter space, such as the mass of dark matter candidate and various components of the Yukawa couplings in the model. © 2017 The Author(s)


Patel S.K.S.,Konkuk University | Choi S.H.,Korea University | Kang Y.C.,Korea University | Lee J.-K.,Konkuk University
ACS Applied Materials and Interfaces | Year: 2017

A novel type of spherical and porous composites were synthesized to dually benefit from reduced graphene oxide (rGO) and magnetic materials as supports for enzyme immobilization. Three magnetic composite particles of Fe3O4 and rGO containing 71% (rGO-Fe3O4-M1), 36% (rGO-Fe3O4-M2), and 18% (rGO-Fe3O4-M3) Fe were prepared using a one-pot spray pyrolysis method and were used for the immobilization of the model enzymes, laccase and horseradish peroxidase (HRP). The rGO-Fe3O4 composite particles prepared by spray pyrolysis process had a regular shape, finite size, and uniform composition. The immobilization of laccase and HRP on rGO-Fe3O4-M1 resulted in 112 and 89.8% immobilization efficiency higher than that of synthesized pure Fe3O4 and rGO particles, respectively. The stability of laccase was improved by approximately 15-fold at 25 °C. Furthermore, rGO-Fe3O4-M1-immobilized laccase exhibited 92.6% of residual activity after 10 cycles of reuse and was 192% more efficient in oxidizing different phenolic compounds than the free enzyme. Therefore, these unique composite particles containing rGO and Fe3O4 may be promising supports for the efficient immobilization of industrially important enzymes with lower acute toxicity toward Vibrio f ischeri than commercial pure Fe3O4 particles. © 2016 American Chemical Society.


Kang H.-S.,Konkuk University | Kim J.-P.,Korea Research Institute of Bioscience and Biotechnology
Journal of Chemical Research | Year: 2017

The organic extract of Sargassum siliquastrum exhibited in vitro radical scavenging activity in our screening of marine brown algae collected in Jeju Island, Korea. Bioactivity-guided fractionation of the organic extract led to the isolation of two new meroterpenoids, named sargachromanols S and T, along with the known meroterpenoids, isopolycerasoidol, nahocol D2, and sargachromanols D, E, G, and I. The planar structures of the new compounds were determined by the analysis of spectroscopic data obtained by HREIMS and 1D and 2D NMR. The structures of the new compounds sargachromanols S and T were closely related to those of previously isolated sargachromanols D and A, respectively. The isolated compounds showed radical scavenging activities in vitro against 1,1-diphenylpicrylhydrazyl and 2,2′-azidobis(3-ethylbenzothiazoline-6-sulfonate) radicals. © 2017, Science Reviews 2000 Ltd. All rights reserved.


Nair P.M.G.,Konkuk University | Chung I.M.,Konkuk University
Science of the Total Environment | Year: 2017

This study examined the mechanism of toxicity in Arabidopsis thaliana seedlings to zinc oxide nanoparticles (ZnO NPs) and zinc (Zn) ions. We subjected plants to different ZnO NPs and Zn ion concentrations (0, 20, 50, 100 and 200 mg/L) and analyzed resulting morphological changes, transcriptional regulation of genes involved in Zn-homeostasis, macro- and microelement homeostasis, as well as auxin regulation. Except for 20 mg/L, the fresh weight and primary root length was reduced after exposure to all other concentrations of Zn ion and ZnO NP concentrations. An increase in lateral root formation (19 and 32%) was observed after exposure to 20 and 50 mg/L of Zn ions respectively; whereas 20 mg/L ZnO NPs treatment triggered a 9% increase in lateral root formation. Both qualitative, using Zynpyr-1 fluorescent probe and quantitative analysis revealed Zn uptake and translocation from roots to shoots after Zn ion exposure. However, ZnO NPs-treated seedlings resulted in no root to shoot translocation and Zn accumulation was mainly located in root tips, primary-lateral root junctions and root- shoot junctions. The macronutrients viz. P (1.34 mg/kg DW), K (13.29 mg/kg DW), S (1.29 mg/kg DW) and micronutrients Cu (0.004 mg/kg DW) and Fe (0.345 mg/kg DW) contents were highly decreased as a result of exposure to 200 mg/L of Zn ions. Similarly, the highest reduction of P (2.30 mg/kg DW), K (6.36 mg/kg DW), S (2.63 mg/kg DW) and Cu (0.004 mg/kg DW) was observed after exposure to 200 mg/L of ZnO NPs. Gene regulation studies indicated the transcriptional modulation of various genes involved in Zn, macro- and micro nutrient homeostasis as well as hormone regulation. Taken together, it was observed that the mechanism of toxicity of Zn ions and ZnO NPs were different. These findings will help to design safer strategies for the application of ZnO NPs as plant fertilizer without compromising the morphological and nutritional qualities as well as for the future phytoremediation purposes. © 2016 Elsevier B.V.


Ntuli N.,Konkuk University | Han S.,Konkuk University
International Conference on ICT Convergence | Year: 2012

Named Data Networking (NDN) is an example of studies that attempt to adapt the Internet architecture to new Internet usage patterns. To improve performance, named data is cached in NDN routers at different levels of the network hierarchy. However, caching data may be exploited to compromise consumer privacy using an attack called cache snooping. Cache snooping is the process of determining whether certain data are present on a given router cache and attribute that data to consumers. In this paper, we propose an approach to detect cache snooping attempts for low-level NDN routers. © 2012 IEEE.


Seo C.H.,Konkuk University | Kim S.H.,Konkuk University
Materials and Structures/Materiaux et Constructions | Year: 2017

The pores of lightweight aggregates (LWAs) cause problems with the quality control and pumpability of lightweight aggregate concrete (LWAC), but offer a number of advantages in terms of weight saving and insulation. This paper presents pre-research for evaluating and predicting the pumpability of LWAC, which includes a test method developed for determining the pressurized absorption characteristics of LWAs. The test equipment needed for this consists of a pressure vessel combined with a plug to approximate a pump piston and provide pressurization by means of a loading device. A displacement meter is also included to measure the range of plug movement during pressurization. The testing procedure consists of six steps: adjustment of water levels, aggregate input, greasing, alignment, deaeration within the vessel, and finally pressurization with measurement. Equations to estimate porosity and provide a reference load-displacement curve are derived from the results of testing hollow spheres, and then applied to determining the absorbed void volume ratio of aggregate under pressure from the displacement of the plug. The pressurized absorptive characteristics of LWAs are also estimated by comparing the slope of their load-displacement curve to the reference curve. This reveals that the displacement of LWAC is highly dependent on the displacement of the LWA it contains. © 2016, RILEM.


Kwon W.B.,Konkuk University | Kim B.G.,Konkuk University
Animal Science Journal | Year: 2017

An experiment was conducted to determine the standardized total tract digestibility (STTD) of phosphorus (P) in five sources of inorganic phosphate fed to growing pigs, including dicalcium phosphate (DCP), monodicalcium phosphate (MDCP), monocalcium phosphate (MCP), tricalcium phosphate (TCP) and monosodium phosphate (MSP, reagent grade). Six barrows (42.4 ± 1.1 kg) individually housed in metabolism crates were allotted to a 6 × 6 Latin square design with six dietary treatments and six periods. Each experimental period consisted of a 4 day adaptation period and a 5 day collection period. The five experimental diets contained 0.24 to 0.34% of P from each inorganic phosphate as a sole source of P. A P-free diet was also prepared to estimate the basal endogenous loss of P. The STTD of P in MSP (94.9%) was not different from the STTD of P in MCP (93.0%), but was greater (P < 0.05) than that in DCP, MDCP and TCP (87.0, 86.5 and 71.3%, respectively). In conclusion, digestibility of P in reagent-grade MSP was greater than that in feed-grade inorganic phosphates such as DCP, MDCP and TCP, and digestibility of P in DCP and MDCP was greater than that in the TCP. © 2017 Japanese Society of Animal Science.


Kang M.,Konkuk University
Pacific Asia Conference on Information Systems, PACIS 2016 - Proceedings | Year: 2016

From a relational perspective, this study suggests new types of knowledge transfer based on the tenure difference between a knowledge source and a recipient, and explores different motivational mechanism for each type of knowledge transfer. This approach is different from previous ones treating a tenure difference as a cognitive difference that prohibits knowledge transfer. The research model based on the theory of planned behavior was verified using structural equation modeling. The results show that self-efficacy is the strongest antecedent of downward knowledge transfer. On the other hand, in upward knowledge transfer, subjective norm is the most influential. Lastly, in lateral knowledge transfer, expected reciprocity shows a significant effect, but in the negative direction. These results validate the usefulness of the relational approach in understanding the motivational mechanisms of knowledge transfer.


Li Z.,Konkuk University | Kim S.-J.,Konkuk University
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2017

This paper reports a pulsatile micromixer without using any dynamic off-chip controllers and only relies on constant water-head pressure. This significantly differs from other pulsatile micromixers that use expansive, bulky controllers including high-voltage power supplies and function generators. The device is composed of self-actuated oscillator and mixer units, both of which include microfluidic valves and flexible membranes, With a constant input of water-head pressure, the oscillator unit generates pulsatile pressure to drive the mixer unit, thereby producing narrow periodic fluidic bands of two solutions for rapid mixing. The micromixer achieves up to 95% mixing efficiency in the flow rate and flow switching frequency of 2-20 μL/min and 14-20 Hz, respectively. © 2017 IEEE.


Hong Y.J.,Korea University | Lee J.-K.,Konkuk University | Chan Kang Y.,Korea University
Journal of Materials Chemistry A | Year: 2017

Carbon yolk-shell microspheres are ideal sulfur host materials for Li-S batteries because they can accommodate the volume expansion of sulfur during charge-discharge cycles. In this study, yolk-shell structured carbon microspheres are prepared by spray pyrolysis, and their formation mechanism is investigated. SnO2/carbon-carbon core-shell microspheres, prepared by one-step spray pyrolysis using a solution containing tin(ii) oxalate, polyvinylpyrrolidone (PVP), and sucrose, are used as precursor microspheres; the shell and core are formed from PVP and sucrose, respectively. Carbon yolk-shell microspheres with a carbon-void-carbon configuration are prepared by the elimination of SnO2 using Se under a reducing atmosphere. The carbon yolk-shell microspheres prepared from the solution containing sucrose have more filled yolk than the microspheres prepared from the solution without sucrose. The first discharge and charge capacities of the sulfur infiltrated carbon yolk-shell microspheres with a filled yolk at a current density of 0.1 A g−1 are 1503 and 1368 mA h g−1, respectively. The discharge capacity of the microspheres after the 150th cycle at a current density of 0.5 A g−1 is 602 mA h g−1. The microspheres have high reversible discharge capacities of 817, 735, 626, 513, and 340 mA h g−1 at the current densities of 0.5, 1, 2, 4, and 10 A g−1, respectively. The sulfur-infiltrated carbon yolk-shell microspheres with the filled yolk show superior rate performance compared to the hollow microspheres with negligible yolk. © The Royal Society of Chemistry.


Prabhu N.S.,Konkuk University | Hyungdon Y.,Konkuk University
Research Journal of Biotechnology | Year: 2017

Genetic incorporation of unnatural amino acids such as analogs of phenylalanine, histidine, tryptophan and 22nd proteinogeneic amino acid pyrrolysine is accomplished by pyrrolysyl tRNA synthetases engineered through rational engineering and directed evolutionary approaches. It is demonstrated that the E. coli phenylalanine tRNA synthetase shares active similarity with pyrrolysyl tRNA synthetases of Methanosarcina sp. and further engineering has been done to incorporate Phenylalanine analogs. Until now around 50 new engineered variants were reported for the genetic incorporation of more than 100 unnatural amino acids. In order to incorporate specific unnatural amino acid, unique engineered pyrrolysyl tRNA synthetase is required. This is the major limitation of this study which can be overcome by using polyspecific tRNA synthetase. In this study, we carried out high throughput in silico analysis to predict the polyspecificity of 10 different tRNA synthetases that encode 45 different phenylalanine analogs. Among the 10 tRNA synthetases, 3 different tRNA synthetases show polyspecificity that can encode 45 different phenylalanine analogs.


Dang V.B.,Konkuk University | Kim S.-J.,Konkuk University
Electrophoresis | Year: 2017

Microfluidic systems with modular components are attractive alternatives to monolithically integrated microfluidic systems because of their flexibility. In this study, we apply the modular concept on a water-head-pressure-driven microfluidic oscillator and obtain a widely tunable flow rate and fluidic switching period. Modular fluidic resistors can be easily mounted onto and demounted from a main chip by means of plastic male connectors. The connectors enable a leak-free connection between the modular resistors and main chip (leakage pressure > 140 kPa). With modular resistors, we show independent control of the flow rate and flow switching period of the oscillator system in a wide range (2.5 s-6.4 h and 2 μL/min-2 mL/min). This modular approach can be used to enhance the flexibility of instruction-embedded microfluidic circuits in which their operational range is limited. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Jeong T.G.,Konkuk University
Asian Pacific journal of cancer prevention : APJCP | Year: 2016

BACKGROUND: Correlation between colorectal cancer (CRC) and abdominal obesity has been established, but there is a paucity of data on non-obese CRC patients. The aim of this study was to establish the characteristics of CRCs that occur in such patients.MATERIALS AND METHODS: Consecutive CRC patients without cachexia were included. Unintended body weight loss, T4- or M1-staged CRCs, extensive lymph node involvement, or synchronous malignancy were classified as cachectic conditions. Abdominal fat volumes were measured using a multidetector CT unit with software (Rapidia, INFINITT, Seoul, Korea).RESULTS: Of the newly-diagnosed CRC patients, 258 non-cachectic and 88 cachectic patients were analyzed. The cancer size (p<0.001) and T stage (p<0.001) were inversely correlated with body mass index (BMI), visceral fat and subcutaneous fat volumes. Cancer size was the only independent factor related to BMI (p=0.016), visceral fat volume (p=0.002), and subcutaneous fat volume (p=0.027). In non-cachectic patients, a significant inverse correlation was found only between the cancer size and visceral fat volume (p=0.017).CONCLUSIONS: Non-obese CRC patients tend to have larger CRC lesions than their obese counterparts even under non-cachectic conditions. Such an inverse correlation between cancer size and visceral fat volume suggests that considerable CRCs are not correlated with abdominal obesity.


Lee D.,Konkuk University | Lee C.,Konkuk University
Proceedings of the International Astronautical Congress, IAC | Year: 2016

Staged hybrid rocket engine (HRE) is a concept which minimizes the performance variation with respect to O/F shifting, while maintaining the key advantages of HRE. It uses a hybrid gas generator(GG), as a primary combustor, which utilizes solid fuel and liquid oxidizer to produce fuel-rich effluent, which is then expelled and mixed with additionally aft-injected oxidizer in the secondary combustor for a stoichiometric combustion. A key component of a staged HRE is the secondary combustion, and this has been the focus of present paper. In order to maximize the combustion performance, it is vital to have a good oxidizer/effluent mixing and therefore studying of this mixing characteristic is essential. Also, to maximize the benefit of experimental tests, it is necessary to choose and narrow down a test matrix that would likely perform a good combustion performance. Therefore, the sensitivity of configurations and flow conditions, including inlet angles, inlet diameters, and O/F momentum ratio, on mixing and combustion performances should be firstly investigated. The chosen methodology is two-dimensional reacting flow computational fluid dynamics (CFD) modeling with a probability density function combustion model. A key advantage of CFD modeling is that, it is possible to evaluate a wide range of configurations and flow conditions on combustion performance, which may be very difficult to be designed and performed in real combustion test. To evaluate the combustion performance, efficiency based on temperature rise was used for both CFD and experimental results. HTPB with 28% oxygen/72% nitrogen mixture oxidizer (O/F of 2.5) was used to simulate the effluent, which was reported to be the optimal formulation in hybrid GG of staged HRE. As for the oxidizer, gaseous oxygen was used. For all modeling, measured data from the combustion tests were used to set boundary conditions as realistic as possible. To validate the CFD code, ramjet combustor configuration used by Chao, is adopted in this study. And, the present methodology of turbulent reacting flow is satisfactory with respect to data reported. With use of CFD modeling, it would be possible to evaluate the combustion performance differences of various configurations and flow conditions. Hence, a wide range of case study is planned to be performed with a goal to analyze and estimate the combustion performance. Then, a test matrix will be carefully chosen for the experimental test for validation purpose. Finally, based on results, the optimal configuration and flow condition of secondary combustion will be presented. Copyright © 2016 by the International Astronautical Federation (IAF). All rights reserved.


Kwon C.H.,Konkuk University | Kim S.-H.,Konkuk University
Korean Journal of Anesthesiology | Year: 2017

The incidence of intraoperative arrhythmia is extremely high, and some arrhythmias require clinical attention. Therefore, it is essential for the anesthesiologist to evaluate risk factors for arrhythmia and understand their etiology, electrophysiology, diagnosis, and treatment. Anesthetic agents reportedly affect normal cardiac electrical activity. In the normal cardiac cycle, the sinoatrial node initiates cardiac electrical activity through intrinsic autonomous pacemaker activity. Sequential atrial and ventricular contractions result in an effective cardiac pumping mechanism. Arrhythmia occurs due to various causes, and the cardiac pumping mechanism may be affected. A severe case may result in hemodynamic instability. In this situation, the anesthesiologist should eliminate the possible causes of arrhythmia and manage the condition, creating hemodynamic stability under proper electrocardiographic monitoring. © the Korean Society of Anesthesiologists, 2017.


Yu K.,Konkuk University
Journal of the Korean Statistical Society | Year: 2017

In many statistical applications, the variability of the data is an important issue. For instance, in the regression analysis, researchers often meet the heteroscedasticity problem. There is a wide body of literature about the nonparametric estimation of the conditional variance function in one-dimensional case. However there are only few papers about the nonparametric estimation of the conditional variance function when there are several regressors in the model. In this paper, we propose a smooth backfitting estimator for the multiplicative conditional variance function and study the asymptotic property and finite sample performance via simulation studies. © 2017 The Korean Statistical Society.


News Article | April 17, 2017
Site: www.eurekalert.org

An eco-friendly method to synthesize DNA-copper nanoflowers with high load efficiencies, low cytotoxicity, and strong resistance against nucleases has been developed by Professor Hyun Gyu Park in the Department of Chemical and Biomolecular Engineering and his collaborators. The research team successfully formed a flower-shaped nanostructure in an eco-friendly condition by using interactions between copper ions and DNA containing amide and amine groups. The resulting nanoflowers exhibit high DNA loading capacities in addition to low cytotoxicity. Flower-shaped nanocrystals called nanoflowers have gained attention for their distinct features of high surface roughness and high surface area to volume ratios. The nanoflowers have been used in many areas including catalysis, electronics, and analytical chemistry. Of late, research breakthroughs were made in the generation of hybrid inorganic-organic nanoflowers containing various enzymes as organic components. The hybridization with inorganic materials greatly enhanced enzymatic activity, stability, and durability compared to the corresponding free enzymes. Generally, the formation of protein nanocrystals requires high heat treatment so it has limitations for achieving the high loading capacities of intact DNA. The research team addressed the issue, focusing on the fact that nucleic acids with well-defined structures and selective recognition properties also contain amide and amine groups in their nucleobases. They proved that flower-like structures could be formed by using nucleic acids as a synthetic template, which paved the way to synthesize the hybrid nanoflowers containing DNA as an organic component in an eco-friendly condition. The team also confirmed that this synthetic method can be universally applied to any DNA sequences containing amide and amine groups. They said their approach is quite unique considering that the majority of previous works focused on the utilization of DNA as a linker to assemble the nanomaterials. They said the method has several advantageous features. First, the 'green' synthetic procedure doesn't involve any toxic chemicals, and shows low cytotoxicity and strong resistance against nucleases. Second, the obtained nanoflowers exhibit exceptionally high DNA loading capacities. Above all, such superior features of hybrid nanoflowers enabled the sensitive detection of various molecules including phenol, hydrogen peroxide, and glucose. DNA-copper nanoflowers showed even higher peroxidase activity than those of protein-copper nanoflowers, which may be due to the larger surface area of the flower- shaped structures, creating a greater chance for applying them in the field of sensing of detection of hydrogen peroxide. The research team expects that their research will create diverse applications in many areas including biosensors and will be further applied into therapeutic applications. Professor Park said, "The inorganic component in the hybrid nanoflowers not only exhibits low cytotoxicity, but also protects the encapsulated DNA from being cleaved by endonuclease enzymes. Using this feature, the nanostructure will be applied into developing gene therapeutic carriers." This research was co-led by Professor Moon Il Kim at Gachon University and KAIST graduate Ki Soo Park, currently a professor at Konkuk University, is the first author. The research was featured as the front cover article of the Journal of Materials Chemistry B on March 28, Issue 12, published by the Royal Society of Chemistry. The research was funded by the Mid-Career Researcher Support Program of the National Research Foundation of Korea and the Global Frontier Project of the Ministry of Science, ICT & Future Planning.


News Article | April 17, 2017
Site: www.cemag.us

An eco-friendly method to synthesize DNA-copper nanoflowers with high load efficiencies, low cytotoxicity, and strong resistance against nucleases has been developed by Professor Hyun Gyu Park and his collaborators in the Korea Advanced Institute of Science and Technology’s (KAIST) Department of Chemical and Biomolecular Engineering. The research team successfully formed a flower-shaped nanostructure in an eco-friendly condition by using interactions between copper ions and DNA containing amide and amine groups. The resulting nanoflowers exhibit high DNA loading capacities in addition to low cytotoxicity. Flower-shaped nanocrystals called nanoflowers have gained attention for their distinct features of high surface roughness and high surface area to volume ratios. The nanoflowers have been used in many areas including catalysis, electronics, and analytical chemistry. Of late, research breakthroughs were made in the generation of hybrid inorganic-organic nanoflowers containing various enzymes as organic components. The hybridization with inorganic materials greatly enhanced enzymatic activity, stability, and durability compared to the corresponding free enzymes. Generally, the formation of protein nanocrystals requires high heat treatment so it has limitations for achieving the high loading capacities of intact DNA. The research team addressed the issue, focusing on the fact that nucleic acids with well-defined structures and selective recognition properties also contain amide and amine groups in their nucleobases. They proved that flower-like structures could be formed by using nucleic acids as a synthetic template, which paved the way to synthesize the hybrid nanoflowers containing DNA as an organic component in an eco-friendly condition. The team also confirmed that this synthetic method can be universally applied to any DNA sequences containing amide and amine groups. They said their approach is quite unique considering that the majority of previous works focused on the utilization of DNA as a linker to assemble the nanomaterials. They said the method has several advantageous features. First, the “green” synthetic procedure doesn’t involve any toxic chemicals, and shows low cytotoxicity and strong resistance against nucleases. Second, the obtained nanoflowers exhibit exceptionally high DNA loading capacities. Above all, such superior features of hybrid nanoflowers enabled the sensitive detection of various molecules including phenol, hydrogen peroxide, and glucose. DNA-copper nanoflowers showed even higher peroxidase activity than those of protein-copper nanoflowers, which may be due to the larger surface area of the flower- shaped structures, creating a greater chance for applying them in the field of sensing of detection of hydrogen peroxide. The research team expects that their research will create diverse applications in many areas including biosensors and will be further applied into therapeutic applications. Park says, “The inorganic component in the hybrid nanoflowers not only exhibits low cytotoxicity, but also protects the encapsulated DNA from being cleaved by endonuclease enzymes. Using this feature, the nanostructure will be applied into developing gene therapeutic carriers.” This research was co-led by Professor Moon Il Kim at Gachon University and KAIST graduate Ki Soo Park, currently a professor at Konkuk University, is the first author. The research was featured as the front cover article of the Journal of Materials Chemistry B on March 28, Issue 12, published by the Royal Society of Chemistry. The research was funded by the Mid-Career Researcher Support Program of the National Research Foundation of Korea and the Global Frontier Project of the Ministry of Science, ICT & Future Planning.


Popok V.N.,University of Rostock | Popok V.N.,University of Aalborg | Barke I.,University of Rostock | Campbell E.E.B.,University of Edinburgh | And 2 more authors.
Surface Science Reports | Year: 2011

The current paper presents a state-of-the-art review in the field of interaction of atomic and molecular clusters with solids. We do not attempt to overview the entire broad field, but rather concentrate on the impact phenomena: how the physics of the clustersurface interaction depends on the kinetic energy and what effects are induced under different energetic regimes. The review starts with an introduction to the field and a short history of cluster beam development. Then fundamental physical aspects of cluster formation and the most common methods for the production of cluster beams are overviewed. For clustersurface interactions, one of the important scenarios is the low-energy regime where the kinetic energy per atom of the accelerated cluster stays well below the binding (cohesive) energy of the cluster constituents. This case is often called soft landing: the deposition typically does not induce cluster fragmentation, i.e. the clusters tend to preserve their composition but not necessarily their shape. Specific characteristic phenomena for soft landing of clusters are summarized. They pave the way for the use of cluster beams in the formation of nanoparticle arrays with required properties for utilization in optics and electronics, as magnetic media and catalysts, in nanobiology and nanomedicine. We pay considerable attention to phenomena occurring on impact of clusters with increased kinetic energies. In particular, we discuss the physics of the intermediate regime between deposition and implantation, i.e. slight cluster embedding into the surfaceotherwise known as cluster pinning. At higher impact energies, cluster structure is lost and the impact results in local damage of the surface and often in crater and hillock formation. We consider both experimental data and theoretical simulations and discuss mechanisms of these phenomena. Some analogies to the impact of macroscopic objects, e.g. meteorites are shown. This part of the paper also overviews the research on surface sputtering under high-fluence cluster beam treatment and the existing models explaining how this phenomenon can be used for efficient smoothing of surfaces on the macroscopic scale. Several examples of successful applications of the cluster beam technique for polishing of surfaces are given. We also discuss how the physical sputtering can be combined with reactive accelerated cluster erosion. The latter can be an efficient tool for dry etching of surfaces on the nanoscale. Specificity of cluster (multicomponent projectile) stopping in matter and formation of radiation damage under keV-to-MeV energy implantations are analyzed. The part about fundamental aspects of cluster implantation is followed by several examples of practical applications of keV-energy cluster ion beams. This includes ultra-shallow doping of semiconductors and formation of ultrathin insulating layers. A few examples of MeV-energy cluster implantation, leading to the formation of nanosize hillocks or pillars on the surface as well as to local phase transitions (for instance, graphite-to-diamond) are also discussed. The review is finalized by an outlook on the future development of cluster beam research. © 2011 Elsevier B.V. All rights reserved.


Telke A.A.,Gyeongsang National University | Ghodake G.S.,Kyungpook National University | Kalyani D.C.,Konkuk University | Dhanve R.S.,National Taipei University of Technology | Govindwar S.P.,Shivaji University
Bioresource Technology | Year: 2011

Bacillus sp. ADR secretes an extracellular laccase in nutrient broth, and this enzyme was purified up to 56-fold using acetone precipitation and DEAE-cellulose anion exchange chromatography. The molecular weight of purified laccase was estimated to be 66. kDa using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified laccase oxidized 2,6-dimethoxy phenol, o-tolidine, hydroquinone, l-DOPA and guaiacol. The optimum pH for oxidation of o-tolidine, 2,6-dimethoxy phenol and guaiacol were 3.0, 4.0 and 5.0, respectively. The purified laccase contained 2.7. mol/mol of copper. The laccase was stable up to 40 °C and within the pH range of 7.0-9.0. Well-known inhibitors of multicopper oxidases such as, sodium azide, l-cysteine and dithiothreitol showed significant inhibition of laccase activity. The purified enzyme decolorized structurally different azo dyes with variable decolorization rates and efficiencies of 68-90%. This study is useful for understanding the precise use of Bacillus sp. ADR in the decolorization of textile dyes containing industrial wastewater. © 2010 Elsevier Ltd.


Jeong S.-W.,Kunsan National University | An Y.-J.,Konkuk University
Environmental Monitoring and Assessment | Year: 2012

The Korean government recently proposed expanding the number of soil-quality standards to 30 by 2015. The objectives of our study were to construct a reasonable protocol for screening priority soil contaminants for inclusion in the planned soil quality standard expansion. The chemical ranking system of soil pollution substances (CROSS) was first developed to serve as an analytical tool in chemical scoring and ranking of possible soil pollution substances. CROSS incorporates important parameters commonly used in several previous chemical ranking and scoring systems and the new soil pollution parameters. CROSS uses soil-related parameters in its algorithm, including information related to the soil environment, such as soil ecotoxicological data, the soil toxic release inventory (TRI), and soil partitioning coefficients. Soil TRI and monitoring data were incorporated as local specific parameters. In addition, CROSS scores the transportability of chemicals in soil because soil contamination may result in groundwater contamination. Dermal toxicity was used in CROSS only to consider contact with soil. CROSS uses a certainty score to incorporate data uncertainty. CROSS scores the importance of each candidate substance and assigns rankings on the basis of total scores. Cadmium was the most highly ranked. Generally, metals were ranked higher than other substances. Pentachlorophenol, phenol, dieldrin, and methyl tert-butyl ether were ranked the highest among chlorinated compounds, aromatic compounds, pesticides, and others, respectively. The priority substance list generated from CROSS will be used in selecting substances for possible inclusion in the Korean soil quality standard expansion; it will also provide important information for designing a soil-environment management scheme. © Springer Science+Business Media B.V. 2011.


An J.H.,Konkuk University | Oh B.-K.,Sogang University | Choi J.W.,Sogang University
Journal of Biomedical Nanotechnology | Year: 2013

Tyrosine hydroxylase, the rate-limiting enzyme of catecholamine biosysthesis, is predominantly expressed in several cell groups within the brain, including the dopaminergic neurons of the substantia nigra and ventral tegmental area. We evaluated the efficacy of this protein-detection method in detecting tyrosine hydroxylase in normal and oxidative stress damaged dopaminergic cells. In this study, a coupling of DNA barcode and bead-based immnunoassay for detecting tyrosine hydroxylaser with PCR-like sensitivity is reported. The method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated to remove the conjugated barcode DNA. The DNA barcodes were identified by PCR analysis. The concentration of tyrosine hydroxylase in dopaminergic cell can be easily and rapidly detected using bio-barcode assay. The bio-barcode assay is a rapid and high-throughput screening tool to detect of neurotransmitter such as dopamine. Copyright © 2013 American Scientific Publishers All rights reserved.


Kim J.,Konkuk University | Ma J.,University of Illinois at Urbana - Champaign
Bioinformatics | Year: 2014

Summary: We developed PSAR-Align, a multiple sequence realignment tool that can refine a given multiple sequence alignment based on suboptimal alignments generated by probabilistic sampling. Our evaluation demonstrated that PSAR-Align is able to improve the results from various multiple sequence alignment tools. © 2013 The Author 2013. Published by Oxford University Press. All rights reserved.


Lim C.,Konkuk University | Ito H.,University of Tokyo
Technovation | Year: 2013

Although product innovation for unserved lower end mega markets in large developing countries has been recognized as an opportunity for improving the competitiveness of local firms, limited research has been conducted that explicitly explores how innovation capabilities can be built for these markets. This study investigates Tata Motors' Nano as an exploratory case of building innovation capabilities. This paper shows that the building of innovation capability could be achieved through creating a process that overcomes 'the deficiency problem' in generating radically cheap priced original products. The study's contribution to the literature is that it addresses issues of building local firms' innovation capabilities through creating original products for the unserved lower end market, in which advanced country firms have limited experience. Nano, as an unprecedented innovation in the automobile industry, reveals a path to building innovation capability that has not previously been observed. We show that detailed processes involved in generating an original product for the lower end market provide insights on the strategy in terms of target price setting, initiating innovation process overcoming 'the deficiency problem', and creation of complementary resources. © 2013 Elsevier Ltd.


Kim J.-C.,Konkuk University
Chemical Engineering Journal | Year: 2015

Influential factors were investigated to increase decomposition efficiencies of sulfur compounds using an electron beam. Their initial concentrations, different background gases, and relative humidity were of main concern as the factors. Decomposition efficiency of H2S by primary electrons was lower than those of CH3SH, DMS, and DMDS containing one or two CH3 groups. The G-values increased as their initial concentrations increased and the adsorbed dose decreased. Removal efficiencies were highest for H2S and CH3SH in the simultaneous presence of N and O radicals. In contrast, reactions with the O radical were the most effective when DMS and DMDS were irradiated by electron beam under different background gases. Adding water vapor to the reactors resulted in the increase of decomposition efficiency. © 2014 Elsevier B.V.


Kim H.-J.,Hanyang University | Kim H.-J.,Konkuk University | Moon W.-J.,Institute of Biomedical Science | Han S.-H.,Hanyang University
Journal of Alzheimer's Disease | Year: 2013

BACKGROUND: This study aimed to evaluate the relationship between loss of white matter cholinergic pathways, atrophy of the nucleus basalis of Meynert (NBM), and cognitive function in patients with subcortical ischemic vascular dementia (SIVD) or Alzheimer's disease (AD). METHODS: The participants included 26 SIVD, 17 probable AD with or without white-matter changes, and 20 age-matched healthy controls. Thin-section coronal T2-weighted images were acquired using 3.0 T MR. The extent of white matter hyperintensities within cholinergic pathways were assessed using the cholinergic pathways hyperintensities scale (CHIPS). NBM atrophy was assessed from the thickness of the substantia innominata (SI) at the level of the crossing of the anterior commissure. Cognitive impairment was measured using the Mini-Mental State Examination (MMSE) and Clinical Dementia Rating (CDR). Correlations between CHIPSs, SI thickness, and cognitive impairment were evaluated using the Spearman ranked correlation test. RESULTS: In AD, MMSE scores and CDR were correlated with SI thickness (ρ = 0.450, p = 0.006 and ρ = -0.520, p = 0.030, respectively) but not with CHIPS scores (ρ = -0.160, p = 0.530 and ρ = 0.270, p = 0.292, respectively). By contrast, aggravated MMSE score and CDR in SIVD had a tendency to correlate with elevated CHIPS scores (ρ = -0.344, p = 0.127 and ρ = 0.521, p = 0.021, respectively) but not with SI thickness (ρ = -0.210, p = 0.480 and ρ = 0.080, p = 0.736, respectively). CONCLUSIONS: Loss of cholinergic pathways correlates with cognitive dysfunction in both AD and SIVD. The mechanisms appear to differ: NBM atrophy is likely to be the predominant contributor to cognitive impairments in AD, whereas, the cognitive dysfunction of SIVD was associated with compromised subcortical cholinergic fibers not with nucleus itself. © 2013 IOS Press and the authors. All rights reserved.


Yang J.C.H.,National Taiwan University Hospital | Wu Y.-L.,Guangdong Academy of Medical science | Schuler M.,University of Duisburg - Essen | Sebastian M.,Johannes Gutenberg University Mainz | And 24 more authors.
The Lancet Oncology | Year: 2015

Background: We aimed to assess the effect of afatinib on overall survival of patients with EGFR mutation-positive lung adenocarcinoma through an analysis of data from two open-label, randomised, phase 3 trials. Methods: Previously untreated patients with EGFR mutation-positive stage IIIB or IV lung adenocarcinoma were enrolled in LUX-Lung 3 (n=345) and LUX-Lung 6 (n=364). These patients were randomly assigned in a 2:1 ratio to receive afatinib or chemotherapy (pemetrexed-cisplatin [LUX-Lung 3] or gemcitabine-cisplatin [LUX-Lung 6]), stratified by EGFR mutation (exon 19 deletion [del19], Leu858Arg, or other) and ethnic origin (LUX-Lung 3 only). We planned analyses of mature overall survival data in the intention-to-treat population after 209 (LUX-Lung 3) and 237 (LUX-Lung 6) deaths. These ongoing studies are registered with ClinicalTrials.gov, numbers NCT00949650 and NCT01121393. Findings: Median follow-up in LUX-Lung 3 was 41 months (IQR 35-44); 213 (62%) of 345 patients had died. Median follow-up in LUX-Lung 6 was 33 months (IQR 31-37); 246 (68%) of 364 patients had died. In LUX-Lung 3, median overall survival was 28.2 months (95% CI 24.6-33.6) in the afatinib group and 28.2 months (20.7-33.2) in the pemetrexed-cisplatin group (HR 0.88, 95% CI 0.66-1.17, p=0.39). In LUX-Lung 6, median overall survival was 23.1 months (95% CI 20.4-27.3) in the afatinib group and 23.5 months (18.0-25.6) in the gemcitabine-cisplatin group (HR 0.93, 95% CI 0.72-1.22, p=0.61). However, in preplanned analyses, overall survival was significantly longer for patients with del19-positive tumours in the afatinib group than in the chemotherapy group in both trials: in LUX-Lung 3, median overall survival was 33.3 months (95% CI 26.8-41.5) in the afatinib group versus 21.1 months (16.3-30.7) in the chemotherapy group (HR 0.54, 95% CI 0.36-0.79, p=0.0015); in LUX-Lung 6, it was 31.4 months (95% CI 24.2-35.3) versus 18.4 months (14.6-25.6), respectively (HR 0.64, 95% CI 0.44-0.94, p=0.023). By contrast, there were no significant differences by treatment group for patients with EGFR Leu858Arg-positive tumours in either trial: in LUX-Lung 3, median overall survival was 27.6 months (19.8-41.7) in the afatinib group versus 40.3 months (24.3-not estimable) in the chemotherapy group (HR 1.30, 95% CI 0.80-2.11, p=0.29); in LUX-Lung 6, it was 19.6 months (95% CI 17.0-22.1) versus 24.3 months (19.0-27.0), respectively (HR 1.22, 95% CI 0.81-1.83, p=0.34). In both trials, the most common afatinib-related grade 3-4 adverse events were rash or acne (37 [16%] of 229 patients in LUX-Lung 3 and 35 [15%] of 239 patients in LUX-Lung 6), diarrhoea (33 [14%] and 13 [5%]), paronychia (26 [11%] in LUX-Lung 3 only), and stomatitis or mucositis (13 [5%] in LUX-Lung 6 only). In LUX-Lung 3, neutropenia (20 [18%] of 111 patients), fatigue (14 [13%]) and leucopenia (nine [8%]) were the most common chemotherapy-related grade 3-4 adverse events, while in LUX-Lung 6, the most common chemotherapy-related grade 3-4 adverse events were neutropenia (30 [27%] of 113 patients), vomiting (22 [19%]), and leucopenia (17 [15%]). Interpretation: Although afatinib did not improve overall survival in the whole population of either trial, overall survival was improved with the drug for patients with del19 EGFR mutations. The absence of an effect in patients with Leu858Arg EGFR mutations suggests that EGFR del19-positive disease might be distinct from Leu858Arg-positive disease and that these subgroups should be analysed separately in future trials. Funding: Boehringer Ingelheim. © 2015 Elsevier Ltd.


Ahmed J.,Konkuk University | Yuan Y.,Guangdong Institute of Eco environmental and Soil Sciences | Yuan Y.,Chinese Ministry of Water Resources | Zhou L.,Guangdong University of Technology | Kim S.,Konkuk University
Journal of Power Sources | Year: 2012

The high cost and limited resources of precious metals as oxygen reduction catalysts (ORR) hindered the widespread use of microbial fuel cells (MFCs) in practice. Here, the feasibility of metal oxide assisted metal macrocyclic complex was investigated as a catalyst for ORR in an air-cathode MFC. Electrochemical results revealed that cobalt oxide (CoOx) incorporation increased the ORR activity of iron phthalocyanine (FePc). In MFCs, the maximum power density of 654 ± 32 mW m -2 was achieved from the C-CoOx-FePc cathode, which was 37% higher than the power density of carbon supported FePc (C-FePc). The voltage output of the MFC only decreased to 85% of its initial voltage after 50 cycles, suggesting that the synthesized catalyst showed acceptable long-term stability. The voltage drop partially resulted from the covering of biofilm on the catalyst layer. This work provided a potential alternative to Pt in MFCs for sustainable energy generation. © 2011 Elsevier Ltd. All rights reserved. All rights reserved.


Shim S.-A.,Sungshin Women's University | Oh S.K.,Konkuk University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

In an extension of the standard model with a scalar color octet, the possibility of the strongly first-order electroweak phase transition is studied by examining the finite-temperature effective Higgs potential at the one-loop level. It is found that there are wide regions in the parameter space that allow the strongly first-order electroweak phase transition, where the Higgs boson mass is larger than the experimental lower bound of 115 GeV, and the masses of the scalar color octet is around 200 GeV. The parameter regions may be explored at the LHC with respect to the electroweak phase transition. © 2010 The American Physical Society.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Hou T.-J.,Academia Sinica, Taiwan | Lee J.S.,National Tsing Hua University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We explore a new possibility of electroweak baryogenesis in the next-to-minimal supersymmetric standard model. In this model, a strong first-order electroweak phase transition can be achieved due to the additional singlet Higgs field. The new impact of its superpartner (singlino) on the baryon asymmetry is investigated by employing the closed-time-path formalism. We find that the . CP violating source term fueled by the singlino could be large enough to generate the observed baryon asymmetry of the Universe without any conflicts with the current constraints from the non-observation of the thallium, neutron and mercury electric dipole moments. © 2012 Elsevier B.V.


Lee J.-U.,Sogang University | Yoon D.,Sogang University | Kim H.,Konkuk University | Lee S.W.,Konkuk University | Cheong H.,Sogang University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The thermal conductivity of suspended single-layer graphene was measured as a function of temperature using Raman scattering spectroscopy on clean samples prepared directly on a prepatterned substrate by mechanical exfoliation without chemical treatments. The temperature at the laser spot was monitored by the frequency of the Raman 2D band of the Raman scattering spectrum, and the thermal conductivity was deduced by analyzing heat diffusion equations assuming that the substrate is a heat sink at ambient temperature. The obtained thermal conductivity values range from ∼ 1800 W m-1K-1 near 325 K to ∼ 710 W m-1K-1 at 500 K. © 2011 American Physical Society.


Patent
Konkuk University, Omni Bio Pharmaceutical and The Regents Of The University Of Colorado | Date: 2013-01-10

Compositions of and methods for making and using alpha-1 antitrypsin (AAT) fusion molecules or peptide derivatives thereof are disclosed. The compositions and methods relate to generating an AAT fusion molecule of use in pharmaceutically acceptable compositions to treat a subject in need of AAT therapy or treatment. Compositions and methods disclosed herein concern linking AAT or derivative thereof to an immune fragment.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lee J.S.,Chonnam National University | Tseng P.-Y.,National Tsing Hua University
Journal of High Energy Physics | Year: 2014

We perform global fits to general two-Higgs doublet models (2HDMs) with generalized couplings using the most updated data from ATLAS, CMS, and Tevatron. We include both scenarios with CP-conserving and CP-violating couplings. By relaxing the requirement on the discrete symmetries that are often imposed on the Yukawa couplings, we try to see which of the 2HDMs is preferred. We found that (i) Higgcision in 2HDMs can be performed efficiently by using only 4 parameters including the charged Higgs contributions to the Higgs couplings to two photons, (ii) the differences among various types of 2HDMs are very small with respect to the chi-square fits, (iii) tan β is constrained to be small, (iv) the p-values for various fits in 2HDMs are worse than that of the standard model. Finally, we put emphasis on our findings that future precision measurements of the Higgs coupling to the scalar top-quark bilinear {C u S) and tan β may endow us with the discriminating power among various types of 2HDMs especially when Cu S deviates from its SM value 1. © 2014 The Author(s).


Chang J.,National Tsing Hua University | Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lee J.S.,Chonnam National University | Lu C.-T.,National Tsing Hua University
Journal of High Energy Physics | Year: 2014

Associated production of the Higgs boson with a single top quark proceeds through Feynman diagrams, which are either proportional to the hW W, top-Yukawa, or the bottom-Yukawa couplings. It was shown in literature that the interference between the top-Yukawa and the gauge-Higgs diagrams can be significant, and thus the measurement of the cross sections can help pin down the sign and the size of the top-Yukawa coupling. Here we perform a detailed study with full detector simulations of such a possibility at the LHC-14 within the current allowed range of hW W and top-Yukawa couplings, using h → b overline b, γγ, τ + τ -, ZZ → 4ℓmodes. We found that the LHC-14 has the potential to distinguish the size and the sign of the top-Yukawa coupling. Among the channels the h → b overline b mode provides the best chance to probe the signal, followed by the h → γγ mode, which has the advantage of a narrow reconstructed mass peak. We also pointed out that the spatial separation among the final-state particles has the potential in differentiating among various values of the top-Yukawa coupling. © 2014 The Author(s).


Nam S.,Konkuk University | Namkoong W.,Konkuk University | Kang J.-H.,Anyang University, South Korea | Park J.-K.,Anyang University, South Korea | Lee N.,Anyang University, South Korea
Waste Management | Year: 2013

Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. © 2013 Elsevier Ltd.


Lim Y.-T.,Konkuk University | Chow J.W.,Center for Neuroscience and Neurological Recovery | Chae W.-S.,Kyungpook National University
Sports Biomechanics | Year: 2012

This study estimated the lumbar spinal loads at the L4-L5 level and evaluated electromyographic (EMG) activity of right and left rectus abdominis, external and internal obliques, erector spinae, and latissimus dorsi muscles during a golf swing. Four super VHS camcorders and two force plates were used to obtain three-dimensional (3D) kinematics and kinetics of golf swings performed by five male collegiate golfers. Average EMG levels for different phases of golf swing were determined. An EMG-assisted optimization model was applied to compute the contact forces acting on the L4-L5. The results revealed a mean peak compressive load of over six times the body weight (BW) during the downswing and mean peak anterior and medial shear loads approaching 1.6 and 0.6 BW during the follow-through phases. The peak compressive load estimated in this study was high, but less than the corresponding value (over 8 BW) reported by a previous study. Average EMG levels of different muscles were the highest in the acceleration and follow-through phases, suggesting a likely link between co-contractions of paraspinal muscles and lumbar spinal loads. © 2012 Copyright Taylor and Francis Group, LLC.


Ansari M.O.,Aligarh Muslim University | Yadav S.K.,Konkuk University | Yadav S.K.,Korea Institute of Science and Technology | Cho J.W.,Konkuk University | Mohammad F.,Aligarh Muslim University
Composites Part B: Engineering | Year: 2013

Electrically conductive HCl doped polyaniline (Pani)/multi-walled carbon nanotubes (MWCNT) and Pani/graphene (GR) nanocomposites thin films were prepared by mixing method in the presence of different amounts of nanoparticles. Later, film casting was done using N-methyl-2-pyrrolidone as a solvent. The formation of Pani/MWCNT and Pani/GR nanocomposites were characterized by Fourier Transform Infra-Red spectroscopy, Scanning electron microscopy, Raman spectroscopy and X-ray diffraction. Due to poor dispersion of MWCNT in Pani, only Pani/GR nanocomposite films were studied for DC electrical conductivity retention in air by isothermal and cyclic techniques. The films of Pani/GR nanocomposites were observed to be thermally more stable under ambient environmental conditions than pure Pani film. Due to their better dispersion and high stability, such type of nanocomposites may find place as a replacement material for Pani and Pani/MWCNT. © 2012 Elsevier Ltd. All rights reserved.


Hong G.P.,Chonnam National University | Min S.-G.,Konkuk University | Chin K.B.,Chonnam National University
Meat Science | Year: 2012

In this study, the effects of microbial transglutaminase (MTG) and calcium alginate (CA) systems in combination with soybean oil on the emulsion properties of porcine myofibrillar protein (MP) were evaluated under various pH conditions. MTG was shown to improve emulsifying capacity and creaming stability, which increased with increasing pH values up to 6.5. The CA did not influence emulsifying capacity, but it improved the creaming stability of the MP-stabilized emulsions. Both MTG and CA enhanced the rheological properties, but their effects on the physical characteristics of the protein evidenced an opposite trend in relation to pH, i.e., the MTG system improved both the emulsion and gelling properties with increasing pH, whereas the CA system was effective when the pH was lowered. By combining the two MP gelling systems, a stable and pH-insensible emulsion could be produced. © 2011 Elsevier Ltd.


Choi Y.H.,Chonnam National University | Gu Y.-M.,Chonnam National University | Oh J.-W.,Konkuk University | Lee K.-Y.,Chonnam National University
Biochemical and Biophysical Research Communications | Year: 2011

Osterix (Osx) is a novel zinc finger-containing transcription factor that is essential for osteoblast differentiation and bone formation in bone homeostasis. The mitogen-activated protein (MAP) kinases are a group of evolutionarily conserved proline-directed protein serine/threonine kinases that are activated in response to a variety of extracellular stimuli and mediate signal transduction from the cell surface to the nucleus. Erk1/2 plays essential roles in osteoblast differentiation and in supporting osteoclastogenesis, but the precise molecular signaling mechanisms between Osterix and Erk1/2 are not known. We therefore focused on the relationship between Osterix and Erk1/2 during osteoblast differentiation because BMP signaling induces Erk activation in osteoblasts. We investigated the role of the MAPK pathway in regulating protein levels and transcriptional functions of Osterix. We found that Erk activation by overexpression of constitutively active MEK increased the mRNA and protein levels of Osterix and enhanced the transcriptional activity of Osterix, whereas U0126, an inhibitor of MEK, suppressed the protein levels of Osterix and the transcriptional activity. Also, overexpression of constitutively active MEK stabilized Osterix protein. These results suggest that Erk1/2 regulates a major transcription factor, Osterix, during osteoblast differentiation by increasing its protein stability and transcriptional activity. © 2011 Elsevier Inc.


Kang N.J.,Kyungpook National University | Shin S.H.,Konkuk University | Shin S.H.,Seoul National University | Lee H.J.,Seoul National University | And 2 more authors.
Pharmacology and Therapeutics | Year: 2011

Multiple lines of evidences suggest that oxidative stress induced by reactive oxygen species are closely related to multi-stage carcinogenesis. Polyphenols, a group of chemicals with more than one phenol unit or building block per molecule, have been recognized for possessing many health benefits including cancer-preventive effects mainly due to their antioxidant activity. However, polyphenols can directly bind with signaling molecules involved in carcinogenesis and regulate its activity. Moreover, it is noteworthy that the binding between the polyphenol and the target protein is determined by their structural relationship, which implies that different polyphenols have different target proteins, leading to divergent chemopreventive effects. Extracellular stimuli transmit signals into a cell by activating their target signaling cascades involved in carcinogenesis. As an example, Src family kinase, a family of proto-oncogenic tyrosine kinases activated by a variety of oxidative stress and proinflammatory agents, is known to regulate cell proliferation, differentiation, survival and angiogenesis. Src family kinase subsequently activates downstream signal cascades including mitogen-activated protein kinase, phosphoinositol-3-kinase, and nuclear factor-kappaB, thereby inducing cell proliferation and causing cancer. Recent studies demonstrate that polyphenols can directly target signaling cascades involved in inflammation and the development of cancer. Inhibition of the kinases by polyphenols contributes to the attenuation of carcinogenesis. Therefore, the development of polyphenols as direct inhibitors against target proteins is regarded as a rational approach for chemoprevention. This review describes and discusses recent results about the direct interactions of polyphenols and protein kinases in cancer chemoprevention. © 2011 Elsevier Inc.


Park D.,Konkuk University | Markus M.,University of Illinois at Urbana - Champaign
Journal of Hydrology | Year: 2014

The Pecatonica River and several other streams in the Wisconsin Driftless area show a decreasing trend in annual peak flows. Previous studies of the Pecatonica River detected a significant decreasing historical trend in late winter snowmelt-driven floods, while the rainfall-driven spring and summer flood peaks exhibited no significant trend during the period of record. Unlike several previous studies which attribute the decline in flood peaks mainly to changes in land management, we hypothesize that climate change had a significant contribution to the overall decrease in flood peaks. In particular, we hypothesize that the increase in winter temperatures caused the decrease in snow depth, which in turn resulted in a decreasing trend in flood peaks. In an attempt to validate this hypothesis, we used long-term daily precipitation, temperature, and river flow data observed in the watershed as inputs to the Variable Infiltration Capacity (VIC) model to generate other non-monitored climatic variables. Trends in these climatic variables were then related to the trend in flood peaks in the Pecatonica River. Due to the complexity of the hydrologic system and numerous data and modeling-related uncertainties, the above hypothesis cannot be validated with certainty. Nonetheless, the results in two different modes (event and continuous simulation) provide support to the speculation that the decreasing trend in flood peaks was a result of decreasing snow depth. The model runs resulted in a decrease in snow depths for the period of record (1915-2009), increase in sublimation and evaporation, no change in base flow, and mixed results in infiltration. These analyses also suggest that VIC can be used in other similar regions in snowmelt-driven flood peak studies. It should be recognized, however, that the success of these applications can be severely constrained by various uncertainties, including but not limited to, the poor quality or absence of snow depth data. © 2014 Elsevier B.V.


Yoon J.P.,Kyungpook National University | Chung S.W.,Konkuk University | Kim S.H.,Seoul National University | Oh J.H.,Seoul National University
Journal of Shoulder and Elbow Surgery | Year: 2013

Hypothesis: The lift-off, internal rotation lag sign, belly-press, and bear-hug tests are widely used toevaluate the integrity of the subscapularis. We hypothesized that these tests might reflect different types of subscapularis tears and sought to ascertain whether these tests accurately determine the severity of the internal rotation strength deficit and fatty degeneration. Methods: Isokinetic testing and the 4 clinical tests were used preoperatively to evaluate 312 patients who had undergone arthroscopic rotator cuff surgery. Of these, 37 patients had a full-thickness subscapularis tear, 96had a partial-thickness tear, and 179 had no tear. Results: For differentiating any tears from an intact subscapularis, the most sensitive test was the belly-press test (27.8%), and the most specific test was the lift-off test (100%). For differentiating a full-thickness tear from a partial tear, the most sensitive test was the belly-press test (56.8%), and the most specific was the lift-off test (96.9%). A positive lift-off test also most reflected loss of internal rotation strength (mean, 72.2%; 95% confidence interval, 61.9-82.5), followed by the internal rotation lag sign (55.1%; 44.2-66.1) and the belly-press test (45.9%; 36.4-54.4). Conclusions: A positive lift-off test was highly specific for the detection of a full-thickness subscapularis tear and to reflect severe fatty degeneration. The lift-off, internal rotation lag sign, belly-press, and bear-hug tests sequentially predict internal rotation strength deficit and provide discrimination of internal rotation strength impairment. © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lee J.S.,Chonnam National University | Senaha E.,Nagoya University | Tseng P.-Y.,National Tsing Hua University
Journal of High Energy Physics | Year: 2014

Current data on the signal strengths and angular spectrum of the 125.5 GeV Higgs boson still allow a CP-mixed state, namely, the pseudoscalar coupling to the top quark can be as sizable as the scalar coupling: Cu S ≈Cu P =1/2. CP violation can then arise and manifest in sizable electric dipole moments (EDMs). In the framework of two-Higgs-doublet models, we not only update the Higgs precision (Higgcision) study on the couplings with the most updated Higgs signal strength data, but also compute all the Higgs-mediated contributions from the 125.5 GeV Higgs boson to the EDMs, and confront the allowed parameter space against the existing constraints from the EDM measurements of Thallium, neutron, Mercury, and Thorium monoxide. We found that the combined EDM constraints restrict the pseudoscalar coupling to be less than about 10-2, unless there are contributions from other Higgs bosons, supersymmetric particles, or other exotic particles that delicately cancel the current Higgs-mediated contributions. © 2014 The Author(s).


Shin S.Y.,Konkuk University | Choi C.,Chonnam National University | Lee H.G.,Konkuk University | Lim Y.,Konkuk University | Lee Y.H.,Konkuk University
Carcinogenesis | Year: 2012

Interleukin-11 (IL-11), which belongs to a class of IL6-type cytokines, plays an important role in inflammation, motility and invasion in cancer. The ras mutation is frequently found in human cancer, but little is known regarding the transcriptional activation of the IL-11 gene by the Ras signal pathway in tumour cells. In this study, we investigated the role of Ras in the regulation of IL-11 using two different cell model systems: mouse NIH3T3 cells over-expressing oncogenic Ras with a tet-on system and Capan-1 human pancreatic carcinoma cells harbouring a K-ras mutation. We found that IL-11 expression was up-regulated at the transcriptional level by oncogenic Ras. Activation of the AP-1 response element, located between -153 and -30 in the 5'-regulatory region of the IL-11 gene, was necessary for oncogenic Ras-induced IL-11 promoter activation. AP-1 proteins, including Fra-1 and Fra-2, were up-regulated through the Raf/MEK and phosphatidylinositol 3-kinase (PI3K)/Akt pathways by oncogenic Ras. Knockdown of Fra-1 by siRNA in NIH3T3 or Capan-1 cells strongly attenuated oncogenic Ras-induced IL-11 expression. Additionally, inhibition of JNK, p38 and Stat3 abrogated oncogenic Ras-induced IL-11 expression. These results suggest that both the PI3K and Raf pathways are necessary for the expression of IL-11 in oncogenic Ras-mutated cells, and that JNK, p38 and Stat3 also contribute to oncogenic Ras-induced IL-11 expression. © The Author 2012. Published by Oxford University Press. All rights reserved.


Kwon Y.,Konkuk University | Ceperley D.M.,University of Illinois at Urbana - Champaign
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We have performed path-integral Monte Carlo calculations to study 4He adsorption on a single graphene sheet. The 4He-substrate interaction was assumed to be a pairwise sum of the helium-carbon potentials constructed by Carlos and Cole to fit helium scattering data from a graphite surface. We employed both an anisotropic 6-12 Lennard-Jones potential and a spherical 6-12 potential. For both potentials, the first 4He layer has the C 1/3 commensurate structure at a surface density of 0.0636 -2. Vacancy states created in the C 1/3 commensurate solid, however, behave differently depending on the 4He-substrate interaction: a cluster of localized vacancies are formed with the fully anisotropic 6-12 pair potentials while mobile vacancies are found to induce finite superfluid fractions with the substrate potential based on only the isotropic parts of the inter-atomic pair potentials. For the second helium layer we find that exchange among 4He adatoms results in quantum melting of a C 7/12 commensurate structure, which is registered to a first-layer triangular solid. The possible stabilization of this commensurate structure with the addition of 3He impurities is discussed. © 2012 American Physical Society.


Baek S.E.,Konkuk University | Lee K.H.,Konkuk University | Park Y.S.,Yonsei University | Oh D.-K.,Konkuk University | And 3 more authors.
Journal of Controlled Release | Year: 2014

To minimize the systemic toxicity prevalent to chemotherapeutics, we designed a novel anticancer drug-encapsulating liposome conjugated with an RNA aptamer specific to the prostate specific membrane antigen (PSMA), which is expressed on the surface of prostate cancer cells. The RNA aptamer-conjugated liposome, termed an aptamosome, was prepared by the post-insertion method, in which RNA aptamer-conjugated micelles were inserted into a liposome. These nanosized (90-100 nm) aptamer-conjugated liposomes specifically bind to LNCaP prostate epithelial cells that express PSMA and thus cause the nanoparticles to have significantly enhanced in vitro cellular binding and uptake as compared with nontargeted nanoparticles that lack the PSMA aptamer. Aptamosomes encapsulated with the anticancer drug doxorubicin (Dox) were significantly more toxic to the targeted LNCaP cells than to nontargeted cancer cells. Dox-encapsulating aptamosomes administered to LNCaP xenograft nude mice were selectively retained in tumor tissue. We also demonstrated in vivo anticancer efficacy of the Dox-encapsulating PSMA-aptamosomes on tumor size regression in LNCaP xenograft mice. We suggest that the encapsulation of toxic chemicals with aptamer-conjugated liposomes will enable the use of these bioconjugates in clinical practice with fewer side effects. © 2014 Elsevier B.V.


Choi D.K.,Konkuk University | Koppula S.,Konkuk University | Suk K.,Kyungpook National University
Molecules | Year: 2011

Microglial cells play a dual role in the central nervous system as they have both neurotoxic and neuroprotective effects. Uncontrolled and excessive activation of microglia often contributes to inflammation-mediated neurodegeneration. Recently, much attention has been paid to therapeutic strategies aimed at inhibiting neurotoxic microglial activation. Pharmacological inhibitors of microglial activation are emerging as a result of such endeavors. In this review, natural products-based inhibitors of microglial activation will be reviewed. Potential neuroprotective activity of these compounds will also be discussed. Future works should focus on the discovery of novel drug targets that specifically mediate microglial neurotoxicity rather than neuroprotection. Development of new drugs based on these targets may require a better understanding of microglial biology and neuroinflammation at the molecular, cellular, and systems levels. © 2011.


Cho C.-H.,Keimyung University | Jung S.-W.,Keimyung University | Park J.-Y.,Konkuk University | Song K.-S.,Keimyung University | Yu K.-I.,Keimyung University
Journal of Shoulder and Elbow Surgery | Year: 2013

Background: Recent studies have found a high prevalence of depression, anxiety, and sleep disturbance in patients with chronic musculoskeletal pain. We conducted a study to determine whether shoulder pain for 3 months or longer is correlated with depression, anxiety, and sleep disturbance. Materials and methods: We prospectively evaluated 130 patients who had had shoulder pain for 3 months or longer (group I) and 60 healthy controls (group II). We obtained visual analog scale (VAS) pain score, and scores for the American Shoulder and Elbow Surgeons (ASES), Korean Shoulder Scale (KSS), Hospital Anxiety and Depression Scale (HADS), and Pittsburgh Sleep Quality Index (PSQI). Results: The mean VAS pain score, ASES score, and KSS score in group I were 6.2, 46.6, and 51.5, respectively. In that group, 22.3% had depression, 19.2% had anxiety, and 81.5% had sleep disturbance. The prevalences were higher in group I than in group II. There were no differences in depression, anxiety, or sleep disturbance by age, sex, type of disease, or duration of symptoms in group I. VAS pain scores positively correlated with PSQI scores (. P = .01). ASES and KSS scores negatively correlated with HADS depression and anxiety subscale and PSQI scores (. P < .001). Shoulder pain for 3 months or longer was the strongest predictor of sleep disturbance (. P < .001). Conclusions: Our study demonstrated high prevalence and close relationships of depression, anxiety, and sleep disturbance in patients with shoulder pain for 3 months or longer. These results may indicate importance of the psychologic approach as well as adequate pain control. © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lee J.S.,Chonnam National University | Tseng P.-Y.,National Tsing Hua University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

During the 2014 summer conferences, both the ATLAS and CMS Collaborations of the LHC experiments have demonstrated tremendous efforts in treatment of data and processing more data such that most data on signal strengths have improved, especially the diphoton and fermionic modes of both experiments. Here in this paper we perform an update to our previous model-independent Higgs precision analysis - Higgcision. We found the following: (i) the uncertainties on most couplings shrink about 10%-20%, (ii) the nonstandard (e.g. invisible) decay branching ratio of the Higgs boson is constrained to be less than 19% if only the width is allowed to vary, (iii) the gauge-Higgs coupling Cv is constrained to be 0.94-0.12+0.11, in which the uncertainty is reduced by about 10%, and (iv) the standard model (SM) Higgs boson still provides the best fit to all the Higgs boson data, and compared to the previous results the SM Higgs boson now enjoys a higher p value than the last year. © 2014 American Physical Society.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lee J.S.,Chonnam National University | Tseng P.-Y.,National Tsing Hua University
Journal of High Energy Physics | Year: 2013

After the discovery of the Higgs boson at the LHC, it is natural to start the research program on the precision study of the Higgs-boson couplings to various standard model (SM) particles. We provide a generic framework for the deviations of the couplings from their SM values by introducing a number of parameters. We show that a large number of models beyond the SM can be covered, including two-Higgs-doublet models, supersymmetric models, little-Higgs models, extended Higgs sectors with singlets, and fourth generation models. We perform global fits to the most updated data from CMS, ATLAS, and Tevatron under various initial conditions of the parameter set. In particular, we have made explicit comparisons between the fitting results before and after the Moriond 2013 meetings. Highlights of the results include: (i) the nonstandard decay branching ratio of the Higgs boson is less than 22%; (ii) the most efficient way to achieve the best fit for the data before the Moriond update is to introduce additional particle contributions to the triangular-loop functions of Hγγ and Hgg vertices; (iii) the 1σ allowed range of the relative coupling of HVV is 1.01-0.14 +0.13, which means that the electroweak-symmetry breaking contribution from the observed Higgs boson leaves only a small room for other Higgs bosons; (iv) the current data do not rule out pseudoscalar couplings nor pseudoscalar contributions to the Hγγ and Hgg vertices; and (v) the SM Higgs boson provides the best fit to all the current Higgs data. © 2013 SISSA, Trieste, Italy.


Ko S.M.,Konkuk University | Choi J.W.,Konkuk University | Song M.G.,Konkuk University | Shin J.K.,Konkuk University | And 3 more authors.
European Radiology | Year: 2011

Objective: To evaluate the feasibility and diagnostic accuracy of adenosine-stress dual-energy computed tomography (DECT) for detecting haemodynamically significant stenosis causing reversible myocardial perfusion defect (PD) compared with stress perfusion magnetic resonance imaging (SP-MRI) and conventional coronary angiography (CCA). Methods: Fifty patients with known coronary artery disease (CAD) detected by dual-source CT (DSCT) were investigated by contrast-enhanced, stress DECT with high- and low-energy x-ray spectra settings during adenosine infusion. A colour-coded iodine map was used for evaluation of myocardial PDs compared with rest DSCT perfusion images. Reversible myocardial PDs according to the stress DECT/rest DSCT were compared with SP-MRI on a segmental basis and CCA on a vascular territorial basis. Results: A total of 697 myocardial segments and 123 vascular territories of 41 patients were analysed. Three hundred one segments and 72 vascular territories in 38 patients showed reversible PDs on stress DECT. Stress DECT had 89% sensitivity, 78% specificity and 82% accuracy for detecting segments with reversible PDs seen on SP-MRI (n∈=∈28). Compared with CCA (n∈=∈41), stress DECT had 89% sensitivity, 76% specificity and 83% accuracy for the detection of vascular territories with reversible myocardial PDs that had haemodynamically relevant CAD. Conclusion: Adenosine stress DECT can identify stress-induced myocardial PD in patients with CAD. © 2010 European Society of Radiology.


Wu Y.-L.,Guangdong General Hospital and Guangdong Academy of Medical science | Zhou C.,Shanghai Pulmonary Hospital | Hu C.-P.,Central South University | Feng J.,Jiangsu Provincial Tumor Hospital | And 11 more authors.
The Lancet Oncology | Year: 2014

Background: Afatinib-an oral irreversible ErbB family blocker-improves progression-free survival compared with pemetrexed and cisplatin for first-line treatment of patients with EGFR mutation-positive advanced non-small-cell lung cancer (NSCLC). We compared afatinib with gemcitabine and cisplatin-a chemotherapy regimen widely used in Asia-for first-line treatment of Asian patients with EGFR mutation-positive advanced NSCLC. Methods: This open-label, randomised phase 3 trial was done at 36 centres in China, Thailand, and South Korea. After central testing for EGFR mutations, treatment-naive patients (stage IIIB or IV cancer [American Joint Committee on Cancer version 6], performance status 0-1) were randomly assigned (2:1) to receive either oral afatinib (40 mg per day) or intravenous gemcitabine 1000 mg/m2 on day 1 and day 8 plus cisplatin 75 mg/m2 on day 1 of a 3-week schedule for up to six cycles. Randomisation was done centrally with a random number-generating system and an interactive internet and voice-response system. Randomisation was stratified by EGFR mutation (Leu858Arg, exon 19 deletions, or other; block size three). Clinicians and patients were not masked to treatment assignment, but the independent central imaging review group were. Treatment continued until disease progression, intolerable toxic effects, or withdrawal of consent. The primary endpoint was progression-free survival assessed by independent central review (intention-to-treat population). This study is registered with ClinicalTrials.gov, NCT01121393. Findings: 910 patients were screened and 364 were randomly assigned (242 to afatinib, 122 to gemcitabine and cisplatin). Median progression-free survival was significantly longer in the afatinib group (11·0 months, 95% CI 9·7-13·7) than in the gemcitabine and cisplatin group (5·6 months, 5·1-6·7; hazard ratio 0·28, 95% CI 0·20-0·39; p<0·0001). The most common treatment-related grade 3 or 4 adverse events in the afatinib group were rash or acne (35 [14·6%] of 239 patients), diarrhoea (13 [5·4%]), and stomatitis or mucositis (13 [5·4%]), compared with neutropenia (30 [26·5%] of 113 patients), vomiting (22 [19·5%]), and leucopenia (17 [15·0%]) in the gemcitabine and cisplatin group. Treatment-related serious adverse events occurred in 15 (6·3%) patients in the afatinib group and nine (8·0%) patients in the gemcitabine and cisplatin group. Interpretation: First-line afatinib significantly improves progression-free survival with a tolerable and manageable safety profile in Asian patients with EGFR mutation-positive advanced lung NSCLC. Afatinib should be considered as a first-line treatment option for this patient population. Funding: Boehringer Ingelheim. © 2014 Elsevier Ltd.


Yu Y.,West China Second Hospital | Yu Y.,University of Texas Southwestern Medical Center | Chen Y.,University of Texas Southwestern Medical Center | Kim B.,University of Texas Southwestern Medical Center | And 14 more authors.
Cell | Year: 2013

Establishment of oligodendrocyte identity is crucial for subsequent events of myelination in the CNS. Here, we demonstrate that activation of ATP-dependent SWI/SNF chromatin-remodeling enzyme Smarca4/Brg1 at the differentiation onset is necessary and sufficient to initiate and promote oligodendrocyte lineage progression and maturation. Genome-wide multistage studies by ChIP-seq reveal that oligodendrocyte-lineage determination factor Olig2 functions as a prepatterning factor to direct Smarca4/Brg1 to oligodendrocyte-specific enhancers. Recruitment of Smarca4/Brg1 to distinct subsets of myelination regulatory genes is developmentally regulated. Functional analyses of Smarca4/Brg1 and Olig2 co-occupancy relative to chromatin epigenetic marking uncover stage-specific cis-regulatory elements that predict sets of transcriptional regulators controlling oligodendrocyte differentiation. Together, our results demonstrate that regulation of the functional specificity and activity of a Smarca4/Brg1-dependent chromatin-remodeling complex by Olig2, coupled with transcriptionally linked chromatin modifications, is critical to precisely initiate and establish the transcriptional program that promotes oligodendrocyte differentiation and subsequent myelination of the CNS. © 2013 Elsevier Inc.


Genovese M.C.,Stanford University | Durez P.,Catholic University of Louvain | Richards H.B.,Novartis | Supronik J.,NZOZ Centrum Medyczne Artur Racewicz | And 9 more authors.
Annals of the Rheumatic Diseases | Year: 2013

Objective: To assess the safety and efficacy of secukinumab, a fully human monoclonal anti-interleukin-17A antibody, in patients with rheumatoid arthritis (RA). Methods: Patients (n=237) with inadequate response to methotrexate were randomly assigned to receive monthly subcutaneous injections of secukinumab 25 mg, 75 mg, 150 mg, 300 mg or placebo. The primary endpoint was the American College of Rheumatology 20% response (ACR20) at week 16. Results: Demographics and baseline characteristics were comparable across all treatment groups. The primary efficacy endpoint was not achieved: the proportion of ACR20 responders at week 16 with secukinumab 25-300 mg was 36.0-53.7% versus placebo (34%). Disease activity score in 28 joints (DAS28)- C-reactive protein (CRP) was a secondary endpoint and clinically relevant decreases with secukinumab 75-300 mg were reported versus placebo. Serum high sensitivity CRP levels at week 16 were significantly reduced with secukinumab 75 mg, 150 mg and 300 mg doses versus placebo. The safety profile of secukinumab was consistent with that seen with other biological agents. Most adverse events (AE) were mild to moderate in severity. Infections were slightly more frequent with secukinumab than placebo. Six serious AE were reported: secukinumab 75 mg (one), secukinumab 300 mg (four) and placebo (one). Conclusions: ACR20 response rates differed between secukinumab 75 mg, 150 mg and 300 mg doses and placebo; however, the primary efficacy endpoint was not achieved. Greater decreases in DAS28 were observed with secukinumab 75 mg, 150 mg and 300 mg than placebo. There were no unexpected safety signals and no specific organ-related toxicities. Further trials with secukinumab in the treatment of RA are warranted.


Chang S.,Center for Theoretical Physics of the Universe | Kang S.K.,Seoul National University of Science and Technology | Lee J.-P.,Korea University | Song J.,Konkuk University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

In two Higgs doublet models, there exists an interesting possibility, the hidden light Higgs scenario, that the discovered SM-like Higgs boson is the heavier CP-even Higgs boson H0 and the lighter CP-even h0 has not been observed yet in any experiment. We study the current status of this scenario in Types I, II, X, and Y, through the scans of the parameters with all relevant theoretical and experimental constraints. We employ not only the most up-to-date Higgs signal strength measurements with the feed-down effects, but also all the available LHC exclusion limits from heavy Higgs searches. Adjusting the heavier H0 to the 125 GeV state while hiding the lighter h0 from the LEP Higgs search prohibits the extreme decoupling limit: there exist upper bounds on the masses of the pseudoscalar A0 and the charged Higgs H± below about 600 GeV. In addition, the Z2 symmetry is shown to be a good approximate symmetry since the soft Z2 symmetry breaking parameter m122 should be less than about (45GeV)2. Most interestingly, a few parameters in the Higgs potential and the related Higgs triple and quartic couplings are shown to be meaningfully constrained by the current data. The double Higgs-strahlung process at an e+e- collider is also studied. © 2015 American Physical Society. © 2015 American Physical Society.


Cheung K.,National Center for Theoretical science | Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Keung W.-Y.,National Center for Theoretical science | And 4 more authors.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

Recently, the ATLAS Collaboration recorded an interesting anomaly in diboson production with excesses at the diboson invariant mass around 2 TeV in boosted jets of all the WZ, W+W-, and ZZ channels. We offer a theoretical interpretation of the anomaly using a phenomenological right-handed model with extra W' and Z' bosons. Constraints from narrow total decay widths, dijet cross sections, and W/Z+H production are taken into account. We also comment on a few other possibilities. © 2015 Published by Elsevier B.V.


Shin J.,Seoul Siwonhan Pain Clinic | Kim Y.C.,Seoul National University | Lee S.C.,Seoul National University | Kim J.H.,Konkuk University
Anesthesia and Analgesia | Year: 2013

BACKGROUND: Transforaminal epidural steroid injection (TFESI) is a useful treatment modality for pain management. Most complications of TFESI are minor and transient. However, there is a risk of serious complications such as nerve injury, spinal cord infarct, or paraplegia. Some of the risks are related to direct injury to the vessel or intravascular injection of the particulate steroid. We prospectively tested the hypothesis that the intravascular injection rate of the Whitacre needle is lower than that of the Quincke needle during TFESI. METHODS: This study was a randomized trial of 1376 TFESIs at the S1 level. We collected data of age, gender, height, weight, laterality (right/left), history of lumbosacral spine operation, history of appropriate interval discontinuation of anticoagulation medicines, and underlying disease. During the S1 TFESI, intrasacral bone contact, a blood aspiration test, and real-time fluoroscopy of the intravascular injection using contrast media were investigated. RESULTS: There were no significant differences in the intravascular injection rate with respect to age, gender, height, weight, hypertension, diabetes mellitus, laterality, history of lumbosacral spine operation, or history of appropriate interval discontinuation of anticoagulation medicines. Intravascular injection was significantly associated with a blood aspiration test (P < 0.001), needle tip type (P = 0.002), intrasacral bone contact (P < 0.001), and physicians (some P < 0.05). The use of Quincke needles and intrasacral bone contact increased the rate of intravascular injection. CONCLUSIONS: To reduce the risk of intravascular injection, the use of Whitacre needles without intrasacral bone contact may be a safer and more effective approach. Copyright © 2013 International Anesthesia Research Society.


Kang B.,Pohang University of Science and Technology | Lim S.,Pohang University of Science and Technology | Lee W.H.,Konkuk University | Jo S.B.,Pohang University of Science and Technology | Cho K.,Pohang University of Science and Technology
Advanced Materials | Year: 2013

RGO electrodes with work functions that can be widely tuned using direct surface functionalization are demonstrated by self-assembled monolayers anchored onto the surfaces of the RGO electrodes, which can remarkably enhance the device performance of organic field-effect transistors. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Hong Y.J.,Sejong University | Yang J.W.,Pohang University of Science and Technology | Lee W.H.,Konkuk University | Ruoff R.S.,University of Texas at Austin | And 2 more authors.
Advanced Materials | Year: 2013

Van der Waals (vdW) epitaxial double heterostructures have been fabricated by vdW epitaxy of InAs nanostructures on both sides of graphene. InAs nanostructures diametrically form on/underneath graphene exclusively along As-polar direction, indicating polarity inversion of the double heterostructures. First-principles and density functional calculations demonstrate how and why InAs easily form to be double heterostructures with polarity inversion. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kima D.-M.,Pusan National University | Rahmanb M.A.,Konkuk University | Do M.H.,Pusan National University | Ban C.,Pohang University of Science and Technology | Shim Y.-B.,Pusan National University
Biosensors and Bioelectronics | Year: 2010

An amperometric chloramphenicol (CAP) immunosensor was fabricated by covalently immobilizing anti-chloramphenicol acetyl transferase (anti-CAT) antibody on cadmium sulfide nanoparticles (CdS) modified-dendrimer that was bonded to the conducting polymer (poly 5, 2': 5', 2"-terthiophene-3'-carboxyl acid (poly-TTCA)) layer. The AuNPs, dendrimers, and CdS nanoparticles were deposited onto the polymer layer in order to enhance the sensitivity of the sensor probes. The particle sizes were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The immobilization of dendrimers, CdS, and anti-CAT were confirmed using energy disruptive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and quartz crystal microbalance (QCM) techniques. The detection of CAP was based on the competitive immuno-interaction between the free- and labeled-CAP for active sites of the anti-CAT. Hydrazine was used as the label for CAP, and it electrochemically catalyzed the reduction of H2O2 at -0.35V vs. Ag/AgCl. Under optimized conditions, the proposed immunosensor exhibited a linear range of CAP detection between 50 pg/mL and 950 pg/mL, and the detection limit was 45 pg/mL. The immunosensor was examined in real meat samples for the analysis of CAP. © 2009 Elsevier B.V.


Balasingam S.K.,Ulsan National Institute of Science and Technology | Kang M.G.,Electronics and Telecommunications Research Institute | Jun Y.,Konkuk University
Chemical Communications | Year: 2013

A step towards commercialization of dye-sensitized solar cells (DSSCs) requires more attention to engineering aspects, such as flexibility, the roll to roll fabrication process, the use of cost effective materials, etc. In this aspect, advantages of flexible DSSCs attracted many researchers to contemplate the transparent conducting oxide coated flexible plastic substrates and the thin metallic foils. In this feature article, the pros and cons of these two kinds of substrates are compared. The flexible dye-sensitized solar cells fabricated using metal substrates are briefly discussed. The working electrodes of DSSCs fabricated on various metal substrates, their fabrication methods, the effect of high temperature calcination and drawbacks of back illumination are reviewed in detail. A few reports on the flexible metal substrate based counter electrodes that could be combined with the plastic substrate based working electrodes are also covered at the end. © 2013 The Royal Society of Chemistry.


Park K.-M.,Konkuk University | Park K.-M.,University of Pennsylvania | Kim Y.-H.,University of Ulsan | Marchlinski F.E.,University of Pennsylvania
PACE - Pacing and Clinical Electrophysiology | Year: 2012

The surface electrocardiogram (ECG) is a useful tool to help identify the sites of origin of ventricular tachycardia (VT). Despite such limitations as chest wall deformity and metabolic and drug effects, the analysis of the QRS morphologic patterns and vectors can discern the site of activation of myocardium. There have been described numerous reports about ECG features of idiopathic left-and right-ventricular VT. In this review, we summarized typical ECG characteristics according to the VT sites of origin based on previous reports, with anatomical considerations of the left and right ventricles, including the outflow tracts and epicardium. (PACE 2012;35:1516-1527) ©2012, The Authors. Journal compilation ©2012 Wiley Periodicals, Inc.


Lee W.H.,Konkuk University | Choi H.H.,Pohang University of Science and Technology | Kim D.H.,Soongsil University | Cho K.,Pohang University of Science and Technology
Advanced Materials | Year: 2014

Recent studies of the bias-stress-driven electrical instability of organic field-effect transistors (OFETs) are reviewed. OFETs are operated under continuous gate and source/drain biases and these bias stresses degrade device performance. The principles underlying this bias instability are discussed, particularly the mechanisms of charge trapping. There are three main charge-trapping sites: the semiconductor, the dielectric, and the semiconductor-dielectric interface. The charge-trapping phenomena in these three regions are analyzed with special attention to the microstructural dependence of bias instability. Finally, possibilities for future research in this field are presented. This critical review aims to enhance our insight into bias-stress-induced charge trapping in OFETs with the aim of minimizing operational instability. Recent studies of the bias-stress-driven electrical instability of organic field-effect transistors (OFETs) are reviewed. The principles underlying this bias instability are discussed, particularly the mechanisms of charge trapping. The charge-trapping phenomena in the semiconductor, the dielectric, and the semiconductor-dielectric interface are analyzed with special attention to the microstructural dependence of bias instability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lee H.-J.,Konkuk University | Suk J.-E.,Konkuk University | Patrick C.,University of California at San Diego | Bae E.-J.,Konkuk University | And 5 more authors.
Journal of Biological Chemistry | Year: 2010

Abnormal neuronal aggregation of α-synuclein is implicated in the development of many neurological disorders, including Parkinson disease and dementia with Lewy bodies. Glial cells also show extensive α-synuclein pathology and may contribute to disease progression. However, the mechanism that produces the glial α-synuclein pathology and the interaction between neurons and glia in the disease-inflicted microenvironment remain unknown. Here, we show that α-synuclein proteins released from neuronal cells are taken up by astrocytes through endocytosis and form inclusion bodies. The glial accumulation of α-synuclein through the transmission of the neuronal protein was also demonstrated in a transgenic mouse model expressing human α-synuclein. Furthermore, astrocytes that were exposed to neuronal α-synuclein underwent changes in the gene expression profile reflecting an inflammatory response. Induction of pro-inflammatory cytokines and chemokines correlated with the extent of glial accumulation of α-synuclein. Together, these results suggest that astroglial α-synuclein pathology is produced by direct transmission of neuronal α-synuclein aggregates, causing inflammatory responses. This transmission step is thus an important mediator of pathogenic glial responses and could qualify as a new therapeutic target. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.


Sonne G.,Gothenburg University | Pena-Aza M.E.,Gothenburg University | Gorelik L.Y.,Chalmers University of Technology | Shekhter R.I.,Gothenburg University | And 3 more authors.
Physical Review Letters | Year: 2010

We consider a nanoelectromechanical Josephson junction, where a suspended nanowire serves as a superconducting weak link, and show that an applied dc bias voltage can result in suppression of the flexural vibrations of the wire. This cooling effect is achieved through the transfer of vibronic energy quanta first to voltage-driven Andreev states and then to extended quasiparticle electronic states. Our analysis, which is performed for a nanowire in the form of a metallic carbon nanotube and in the framework of the density matrix formalism, shows that such self-cooling is possible down to the ground state of the flexural vibration mode of the nanowire. © 2010 The American Physical Society.


Park J.S.,Konkuk University | Na H.-K.,KAIST | Min D.-H.,Seoul National University | Kim D.-E.,Konkuk University
Analyst | Year: 2013

Graphene oxide (GO) is known to interact with single-stranded nucleic acids through pi-stacking interactions and hydrogen bonds between the nucleobases and the hexagonal cells of GO. It also quenches the fluorescence when the fluorophore comes near to the GO mesh. When single-stranded (ss) regions of either DNA or RNA are present, those regions were adsorbed onto the surface of GO with a quenching of fluorescence located proximally to the GO surface. We demonstrated that bound single-stranded nucleic acids can be readily dissociated from GO by disrupting hydrogen bonding with urea, which was confirmed with fluorescence measurement and gel electrophoresis. Hydrogen bonding mainly contributes to the interaction between GO and single-stranded nucleic acids such as ssDNA and RNA. The GO-coated mesoporous silica nanoparticles (GO-MSNs) were synthesized for better separation of RNAs from cells. Cellular RNAs were readily adsorbed and eluted with ease by using GO-MSN and urea, respectively, demonstrating that GO-MSN and urea elution is a facile RNA extraction method. This journal is © The Royal Society of Chemistry.


Lee S.G.,Pohang University of Science and Technology | Kim H.,Pohang University of Science and Technology | Choi H.H.,Pohang University of Science and Technology | Bong H.,Pohang University of Science and Technology | And 3 more authors.
Advanced Materials | Year: 2013

The evaporation-induced self-alignment of semiconductor nanowires is achieved using wrinkled elastomeric templates. The wrinkled templates, which have a surface topography that can be tuned via changes in the mechanical strain, are used as both a template to align the nanowires and as a stamp to transfer the aligned nanowires to target substrates. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Park H.,Pohang University of Science and Technology | Yoon J.,Konkuk University | Kim K.,Pohang University of Science and Technology
Expert Systems with Applications | Year: 2013

Under the open innovation paradigm, identification of application areas of the internally developed technologies is important to maximize the profits from them. However, many companies have failed to identify opportunity for additional applications. The fundamental reason is that companies have insufficient understanding of the potential applications of their technologies, because different industries use far different technologies and technological terminologies. However, technologies can be linked with outside industries by analyzing them from the functional perspective, because functions used in different industries are generally similar. Therefore, this article proposes a function-based patent analysis to identify the potential application areas of a technology. In general, technologies in a patent are invented for use in a specific industry, and thus a patent can be categorized into a specific industry. By identifying patents which contain a specific function, industries that use the function can be identified. Industries in which the importance of the function is relatively high can be considered as areas in which technologies performing the function have potential to be applied, and the proposed indexes evaluate the relative importance of the function within each industry. Finally, the practical usefulness of the proposed method was verified by identifying the potential areas in which vortex reduction technology can be applied. © 2013 Elsevier Ltd. All rights reserved.


Hwang H.J.,Konkuk University | Koo J.,Konkuk University | Park M.,Konkuk University | Park N.,Ulsan National Institute of Science and Technology | And 2 more authors.
Journal of Physical Chemistry C | Year: 2013

Graphynes, two-dimensional layers of sp- and sp2-bonded carbon atoms, have recently received considerable attention because of their potential as new Dirac materials. Here, focusing on their large surface area, we explore the applicability of graphynes as lithium ion battery anodes through the first-principles density functional calculations. We have found that Li potential energies are in the range suitable to be used as anodes. Furthermore, the maximum composite of Li-intercalated multilayer α- and γ-graphynes is found to be C6Li3, which corresponds to a specific capacity of 1117 mAh g-1, twice as large as the previous theoretical prediction for graphynes. The volumetric capacity of Liintercalated multilayer α- and γ-graphynes is 1364 and 1589 mAh cm-3, respectively. Both specific and volumetric capacities of Li-intercalated graphynes are significantly larger than the corresponding value of graphite, from which we conclude that multilayer graphynes can serve as high-capacity lithium ion battery anodes. © 2013 American Chemical Society.


Lee H.,Ulsan National Institute of Science and Technology | Park S.-D.,Ulsan National Institute of Science and Technology | Moon J.,Seoul National University | Lee H.,Konkuk University | And 3 more authors.
Chemistry of Materials | Year: 2014

Good cyclability is essential for the potential application of cathode materials. Here, we investigate the structural stability of two-dimensional (2D) Li-layered and three-dimensional (3D) structured polymorphs of Li 2FeSiO4 and Li2MnSiO4 using the density functional theory calculations. We find that all 2D Li-layered polymorphs of both materials are unstable upon full delithiation owing to layer exfoliation, which can lead to an amorphous structure. However, in contrast to the fact that the amorphization of Li2FeSiO4 can be prevented by the formation of the 3D cycled structure that is energetically stable, the 3D cycled structure of Li2MnSiO4 is found to be unstable during delithiationlithiation cycling. As a result, Li 2MnSiO4 easily undergoes amorphization and shows a poor cyclability. © 2014 American Chemical Society.


Park H.,Pohang University of Science and Technology | Yoon J.,Konkuk University | Kim K.,Pohang University of Science and Technology
Scientometrics | Year: 2013

This paper proposes a framework to identify and evaluate companies from the technological perspective to support merger and acquisition (M&A) target selection decision-making. This employed a text mining-based patent map approach to identify companies which can fulfill a specific strategic purpose of M&A for enhancing technological capabilities. The patent map is the visualized technological landscape of a technology industry by using technological proximities among patents, so companies which closely related to the strategic purpose can be identified. To evaluate the technological aspects of the identified companies, we provide the patent indexes that evaluate both current and future technological capabilities and potential technology synergies between acquiring and acquired companies. Furthermore, because the proposed method evaluates potential targets from the overall corporate perspective and the specific strategic perspectives simultaneously, more robust and meaningful result can be obtained than when only one perspective is considered. Thus, the proposed framework can suggest the appropriate target companies that fulfill the strategic purpose of M&A for enhancing technological capabilities. For the verification of the framework, we provide an empirical study using patent data related to flexible display technology. © 2013 Akadémiai Kiadó, Budapest, Hungary.


Ju M.J.,Korea University | Kim J.C.,Konkuk University | Choi H.-J.,Ulsan National Institute of Science and Technology | Choi I.T.,Korea University | And 7 more authors.
ACS Nano | Year: 2013

Highly efficient counter electrodes (CEs) for dye-sensitized solar cells (DSSCs) were developed using thin films of scalable and high-quality, nitrogen-doped graphene nanoplatelets (NGnP), which was synthesized by a simple two-step reaction sequence. The resultant NGnP was deposited on fluorine-doped SnO2 (FTO)/glass substrates by using electrospray (e-spray) coating, and their electrocatalytic activities were systematically evaluated for Co(bpy)3 3+/2+ redox couple in DSSCs with an organic sensitizer. The e-sprayed NGnP thin films exhibited outstanding performances as CEs for DSSCs. The optimized NGnP electrode showed better electrochemical stability under prolonged cycling potential, and its Rct at the interface of the CE/electrolyte decreased down to 1.73 Ω cm2, a value much lower than that of the Pt electrode (3.15 Ω cm2). The DSSC with the optimized NGnP-CE had a higher fill factor (FF, 74.2%) and a cell efficiency (9.05%), whereas those of the DSSC using Pt-CE were only 70.6% and 8.43%, respectively. To the best of our knowledge, the extraordinarily better current-voltage characteristics of the DSSC-NGnP outperforming the DSSC-Pt for the Co(bpy)3 3+/2+ redox couple (in paticular, FF and short circuit current, Jsc) is highlighted for the first time. © 2013 American Chemical Society.


Yoon J.,Konkuk University | Park H.,Pohang University of Science and Technology | Kim K.,Pohang University of Science and Technology
Scientometrics | Year: 2013

Patent maps showing competition trends in technological development can provide valuable input for decision support on research and development (R&D) strategies. By introducing semantic patent analysis with advantages in representing technological objectives and structures, this paper constructs dynamic patent maps to show technological competition trends and describes the strategic functions of the dynamic maps. The proposed maps are based on subject-action-object (SAO) structures that are syntactically ordered sentences extracted using the natural language processing of the patent text; the structures of a patent encode the key findings of the invention and expertise of its inventors. Therefore, this paper introduces a method of constructing dynamic patent maps using SAO-based content analysis of patents and presents several types of dynamic patent maps by combining patent bibliographic information and patent mapping and clustering techniques. Building on the maps, this paper provides further analyses to identify technological areas in which patents have not been granted ("patent vacuums"), areas in which many patents have actively appeared ("technological hot spots"), R&D overlap of technological competitors, and characteristics of patent clusters. The proposed analyses of dynamic patent maps are illustrated using patents related to the synthesis of carbon nanotubes. We expect that the proposed method will aid experts in understanding technological competition trends in the process of formulating R&D strategies. © 2012 Akadémiai Kiadó, Budapest, Hungary.


Kim C.,Konkuk University | Ho D.-H.,Konkuk University | Suk J.-E.,Konkuk University | You S.,Pohang University of Science and Technology | And 7 more authors.
Nature Communications | Year: 2013

Abnormal aggregation of α-synuclein and sustained microglial activation are important contributors to the pathogenic processes of Parkinson's disease. However, the relationship between disease-associated protein aggregation and microglia-mediated neuroinflammation remains unknown. Here, using a combination of in silico, in vitro and in vivo approaches, we show that extracellular α-synuclein released from neuronal cells is an endogenous agonist for Toll-like receptor 2 (TLR2), which activates inflammatory responses in microglia. The TLR2 ligand activity of α-synuclein is conformation-sensitive; only specific types of oligomer can interact with and activate TLR2. This paracrine interaction between neuron-released oligomeric α-synuclein and TLR2 in microglia suggests that both of these proteins are novel therapeutic targets for modification of neuroinflammation in Parkinson's disease and related neurological diseases. © 2013 Macmillan Publishers Limited. All rights reserved.


Jang H.,KAIST | Ryoo S.-R.,Seoul National University | Kim Y.-K.,Seoul National University | Yoon S.,Konkuk University | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2013

A GO-to solution: A simple graphene oxide (GO)-based assay to screen for selective inhibitors of a hepatitis C virus (HCV) helicase along with inhibitors of a severe acute respiratory syndrome coronavirus (SARS CoV) helicase was tested (see scheme). A single screen found five inhibitors highly selective for the HCV helicase orthologous to the SARS CoV helicase. Some of these hits were validated using the same GO-based assay. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kang B.,Pohang University of Science and Technology | Lee W.H.,Konkuk University | Cho K.,Pohang University of Science and Technology
ACS Applied Materials and Interfaces | Year: 2013

Recent progress in organic field-effect transistor (OFET) printing processes is reviewed, and a perspective on the future of the field is discussed. The principles underlying the OFET printing techniques are introduced according to two categories: direct write printing and transfer printing. A comprehensive overview of the use of printing techniques in OFET production processes is also provided. Considerations for improving OFET device performance using printing processes are explored. Prior to OFET commercialization, the OFET printing techniques must satisfy several requirements, as discussed here. © 2013 American Chemical Society.


Park H.,Pohang University of Science and Technology | Kim K.,Pohang University of Science and Technology | Choi S.,Samsung | Yoon J.,Konkuk University
Expert Systems with Applications | Year: 2013

Patent intelligence - the transformation of content found in multiple patents into technical, business, and legal insight - is considered a key factor in gaining a competitive advantage in technologically competitive business environments. Although keyword-based patent intelligence tools are widely used due to their simplicity and ease of use, they are limited in that they cannot represent key technological concepts and inventive knowledge by relying only on the frequency of occurrence of defined keywords. As a remedy, this paper proposes a Subject-Action-Object (SAO)-based patent intelligence system. SAO structures that can be extracted from textual patent information are known as the expertise and inventive findings of the relevant patent. On the basis of semantic analysis of patent SAO structures, our proposed intelligence system constructs patent maps and patent networks. Building on the maps and networks, the system provides specific functionalities including identification of technology trends and significant patents, detection of novel technologies, and identification of potential infringement. This paper describes the architecture of our proposed patent intelligence system in detail, and illustrates the system's functionalities using case studies. We anticipate that our proposed system will be incorporated into the technology planning process to assist experts in the formulation of technology strategies. © 2012 Elsevier B.V. All rights reserved.


Lee M.,Ulsan National Institute of Science and Technology | Ko Y.,Konkuk University | Jun Y.,Konkuk University
Journal of Materials Chemistry A | Year: 2015

Methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell in a flexible fiber shape is developed via a fully dipping process with a mixed solvent of N,N-dimethylformamide (DMF) and N-methyl-2-pyrrolidone (NMP) followed by toluene dipping. We introduce the first-ever effective n-type compact layer through facile anodizing of titanium wire, achieving a considerable power conversion efficiency of 3.85%, which remains stable during bending; spray-deposited silver nanowires (Ag NWs) are used as the top electrode instead of gold. The ease of fabrication, low cost of materials, and all-solid-state structures result in a simple approach to developing electronic textiles for harvesting solar energy and blazes a new trail in the field of fiber-shaped photovoltaics. © The Royal Society of Chemistry 2015.


Park H.,Pohang University of Science and Technology | Yoon J.,Konkuk University
Scientometrics | Year: 2014

Rapid technological advancements and increasing research and development (R&D) costs are making it necessary for national R&D plans to identify the coreness and intermediarity of technologies in selecting projects and allocating budgets. Studies on the coreness or intermediarity of technology sectors have used patent citations, but there are limitations to dealing with patent data. The limitations arise from the most current patents and patents that do not require citations, e.g. Korean patents. Further, few or no studies have simultaneously considered both coreness and intermediarity. Therefore, we propose a patent co-classification based method to measure coreness and intermediarity of technology sectors by incorporating the analytic network process and the social network analysis. Using IPC co-classifications of patents as technological knowledge flows, this method constructs a network of directed knowledge flows among technology sectors and measures the long-term importance and the intermediating potential of each technology sector, despite the limitations of patent-based analyses. Considering both coreness and intermediarity, this method can provide more detailed and essential knowledge for decision making in planning national R&D. We demonstrated this method using Korean national R&D patents from 2008 to 2011. We expect that this method will help in planning national R&D in a rapidly evolving technological environment. © 2013 Akadémiai Kiadó, Budapest, Hungary.


Kwak D.,Pohang University of Science and Technology | Kwak D.,Samsung | Lim J.A.,Korea Institute of Science and Technology | Kang B.,Pohang University of Science and Technology | And 2 more authors.
Advanced Functional Materials | Year: 2013

The high-precision deposition of highly crystalline organic semiconductors by inkjet printing is important for the production of printed organic transistors. Herein, a facile nonconventional lithographic patterning technique is developed for fabricating banks with microwell structures by inkjet printing solvent droplets onto a polymer layer, thereby locally dissolving the polymer to form microwells. The semiconductor ink is then inkjet-printed into the microwells. In addition to confining the inkjet-printed organic semiconductor droplets, the microwells provide a platform onto which organic semiconductor molecules crystallize during solvent evaporation. When printed onto the hydrophilic microwells, the inkjet-printed 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN) molecules undergo self-organization to form highly ordered crystalline structures as a result of contact line pinning at the top corner of the bank and the outward hydrodynamic flow within the drying droplet. By contrast, small crystallites form with relatively poor molecular ordering in the hydrophobic microwells as a result of depinning of the contact line along the walls of the microwells. Because pinning in the hydrophilic microwells occurred at the top corner of the bank, treating the surfaces of the dielectric layer with a hydrophobic organic layer does not disturb the formation of the highly ordered TIPS-PEN crystals. Transistors fabricated on the hydrophilic microwells and the hydrophobic dielectric layer exhibit the best electrical properties, which is explained by the solvent evaporation and crystallization characteristics of the organic semiconductor droplets in the microwell. These results indicate that this technique is suitable for patterning organic semiconductor deposits on large-area flexible substrates for the direct-write fabrication of high-performance organic transistors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lee M.,Ulsan National Institute of Science and Technology | Jo Y.,Korea Institute of Energy Research | Kim D.S.,Korea Institute of Energy Research | Jun Y.,Konkuk University
Journal of Materials Chemistry A | Year: 2015

Organo-metal halide perovskite solar cells have received much attention in the field of photovoltaics in recent years. Herein, we report a flexible perovskite solar cell based on a metal substrate. It showed a power conversion efficiency of over 6% for the first time using a silver thin film as a semi-transparent top electrode on a Ti substrate. This journal is © The Royal Society of Chemistry 2015.


Choi I.,Konkuk University | Kim Y.-K.,KAIST | Min D.-H.,Seoul National University | Lee S.,Konkuk University | Yeo W.-S.,Konkuk University
Journal of the American Chemical Society | Year: 2011

We report on a new surface modification method for grafting a "dynamic" property for on-demand activation of the click reaction. Our approach utilizes the acetylene group masked with dicobalt hexacarbonyl, Co 2(CO) 6, which is not reactive toward the click reaction. Electrochemical treatment reveals the acetylene group on the selected region, which is then used as a chemical handle for surface functionalization via the click reaction with an azide-containing molecule. Electrochemical and chemical conversions on the surface were verified by cyclic voltammetry, X-ray photoelectron spectroscopy, and fluorescence spectroscopy. We have demonstrated immobilization of an azide-modified RGD peptide and promotion of cell adhesion/migration to the region of electrochemical induction. © 2011 American Chemical Society.


Yoon J.,Konkuk University | Kim K.,Pohang University of Science and Technology
Expert Systems with Applications | Year: 2012

Patents are an up-to-date and reliable knowledge source of innovative technologies, and therefore patent analysis has been a vital tool for understanding technological trends and formulating technology strategies. One method of patent analysis is citation-based patent analysis. However, one criticism of the citation-based approach is that it may underestimate new patents because they tend to be less cited. This problem gets worse in fast-moving industries where technology life-cycles shorten and innovative technologies are actively patented. As a remedy, this paper proposes a property-function based patent network using an analysis of patent contents. Properties and functions as the innovation concepts of a system can be extracted using grammatical analysis of patent text. First, this paper represents each patent into a matrix codifying properties, functions and their co-occurrences, and then it constructs a patent network by measuring patent similarities. As a result, the proposed network reveals the internal relationships among patents in a given patent set that many new patents. Furthermore, using several analysis indices, this paper suggests a way to identify technological implications from the network such as the technological importance of new patents, the technological capability of applicants with new patents and the pace of technological progress of new patents. The proposed method is illustrated using silicon-based thin film solar cells. We expect that the proposed method can be incorporated into R&D planning processes to assist researchers and R&D policy makers to identify technological implications related to new patents in fast-moving industries. © 2012 Elsevier Ltd. All rights reserved.


Oh S.,Florida State University | Noh Y.,Konkuk University
Library and Information Science Research | Year: 2013

Public librarians in South Korea assist users in obtaining information on a variety of topics. However, health-related information and services have a lower profile than other services due to a perceived lack of librarian expertise in searching and evaluating health resources. Although public library users are actively seeking health information, it has become critical for both public librarians and users to develop skills for using and evaluating Internet health resources. Therefore, this study was conducted to identify a set of useful criteria to evaluate online health web sites for both librarians and library users. From a comprehensive literature review, 33 criteria related to health website evaluation were identified. Using this set of criteria, South Korean public librarians and users were asked to rate the importance of each criterion in surveys. A strong consensus was found between the two groups. The top 10 most highly rated criteria from both groups were identified and compared. The results led to the development of an initial set of 12 evaluation criteria for health websites. It is expected that the final set of criteria will be used by public librarians to recommend the best health websites to their users. Although the study was conducted in South Korean public libraries, the findings are applicable in providing evaluation services of health websites to libraries worldwide. © 2012.


Huang B.,Tsinghua University | Huang B.,National Renewable Energy Laboratory | Lee H.,Konkuk University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

In this paper, we have systematically studied the structural and electronic properties of vacancy defects and carbon impurity in hexagonal boron nitride (h-BN) by using both normal GGA calculations and advanced hybrid functional calculations. Our calculations show that the defect configurations and the local bond lengths around defects are sensitive to their charge states. The highest negative defect charge states are largely determined by the nearly-free-electron state at the conduction band minimum of BN. Generally, the in-gap defect levels obtained from hybrid functional calculations are much deeper than those obtained from normal GGA calculations. The formation energies of neutral defects calculated by hybrid functional and GGA are close to each other, but the defect transition energy levels are quite different between GGA and hybrid functional calculations. Finally, we show that the charged defect configurations as well as the transition energy levels exhibit interesting layer effects. © 2012 American Physical Society.


Qudrat-Ullah H.,York University | Seong B.S.,Konkuk University
Energy Policy | Year: 2010

System dynamics based simulation models are becoming increasingly popular in the analysis of important energy policy issues including global warming, deregulation, conservation and efficiency. The usefulness of these models is predicated on their ability to link observable patterns of behavior of a system to micro-level structures. This paper argues that the structural validity of the simulation model-right behavior for the right reasons-is a stringent measure to build confidence in a simulation model regardless of how well the model passes behavior validity tests. That leads to an outline of formal structural validity procedures available but less explored in system dynamics modeling 'repertoire'. An illustration of a set of six tests for structural validity of a system dynamics model for energy policy analysis follows. Then using Theil inequality statistics, the behavior validity of the model is also tested. Finally, some conclusions on the increased appeal for simulation models for energy policy analysis and design are presented. © 2009 Elsevier Ltd. All rights reserved.


Liu M.,Rice University | Artyukhov V.I.,Rice University | Lee H.,Rice University | Lee H.,Konkuk University | And 2 more authors.
ACS Nano | Year: 2013

We report an extensive study of the properties of carbyne using first-principles calculations. We investigate carbyne's mechanical response to tension, bending, and torsion deformations. Under tension, carbyne is about twice as stiff as the stiffest known materials and has an unrivaled specific strength of up to 7.5 × 107 N·m/kg, requiring a force of ∼10 nN to break a single atomic chain. Carbyne has a fairly large room-temperature persistence length of about 14 nm. Surprisingly, the torsional stiffness of carbyne can be zero but can be "switched on" by appropriate functional groups at the ends. Further, under appropriate termination, carbyne can be switched into a magnetic semiconductor state by mechanical twisting. We reconstruct the equivalent continuum elasticity representation, providing the full set of elastic moduli for carbyne, showing its extreme mechanical performance (e.g., a nominal Young's modulus of 32.7 TPa with an effective mechanical thickness of 0.772 Å). We also find an interesting coupling between strain and band gap of carbyne, which is strongly increased under tension, from 2.6 to 4.7 eV under a 10% strain. Finally, we study the performance of carbyne as a nanoscale electrical cable and estimate its chemical stability against self-aggregation, finding an activation barrier of 0.6 eV for the carbyne-carbyne cross-linking reaction and an equilibrium cross-link density for two parallel carbyne chains of 1 cross-link per 17 C atoms (2.2 nm). © 2013 American Chemical Society.


Kim S.Y.,Konkuk University | Lee H.R.,Konkuk University | Park K.-S.,Konkuk University | Kim B.-G.,Gyeongnam National University of Science and Technology | Ahn J.-H.,Konkuk University
Applied Microbiology and Biotechnology | Year: 2015

Most flavonoids are glycosylated and the nature of the attached sugar can strongly affect their physiological properties. Although many flavonoid glycosides have been synthesized in Escherichia coli, most of them are glucosylated. In order to synthesize flavonoids attached to alternate sugars such as glucuronic acid and galactoside, E. coli was genetically modified to express a uridine diphosphate (UDP)-dependent glycosyltransferase (UGT) specific for UDP-glucuronic acid (AmUGT10 from Antirrhinum majus or VvUGT from Vitis vinifera) and UDP-galactoside (PhUGT from Petunia hybrid) along with the appropriate nucleotide biosynthetic genes to enable simultaneous production of their substrates, UDP-glucuronic acid and UDP-galactose. To engineer UDP-glucuronic acid biosynthesis, the araA gene encoding UDP-4-deoxy-4-formamido-L-arabinose formyltransferase/UDP-glucuronic acid C-4″ decarboxylase, which also used UDP-glucuronic acid as a substrate, was deleted in E. coli, and UDP-glucose dehydrogenase (ugd) gene was overexpressed to increase biosynthesis of UDP-glucuronic acid. Using these strategies, luteolin-7-O-glucuronide and quercetin-3-O-glucuronide were biosynthesized to levels of 300 and 687 mg/L, respectively. For the synthesis of quercetin 3-O-galactoside, UGE (encoding UDP-glucose epimerase from Oryza sativa) was overexpressed along with a glycosyltransferase specific for quercetin and UDP-galactose. Using this approach, quercetin 3-O-galactoside was successfully synthesized to a level of 280 mg/L. © 2014, Springer-Verlag Berlin Heidelberg.


Park K.S.,Konkuk University | Koh C.E.,University of North Texas | Nam K.,Konkuk University
Industrial Management and Data Systems | Year: 2010

Purpose - Radio frequency identification (RFID) is an important technology for many aspects of business including supply chain management (SCM). The global implications of RFID necessitate cross-national studies of the technology. The purpose of this paper is to conjecture that the way RFID is perceived and implemented and the extent to which RFID impacts business performance will vary from country to country. Using data collected from firms located in the USA and South Korea, the two countries' views regarding the intrinsic attributes, the perceived benefits and risks, and the strategic impact on business performance of implementing RFID are compared. Design/methodology/approach - The authors developed a research instrument to assess the perception of the importance of RFID, the benefits and risks of RFID, and the perceived impact of RFID on business performance. The authors used the instrument to survey executives and managers in the USA and South Korea. Findings - The paper did not find any discernable difference between the two countries in terms of the perception of the importance of RFID, the benefits and risks of RFID, and the perceived impact of RFID on business performance. This shared perception of RFID may be viewed a sign of readiness of the technology to become a global business tool. Research limitations/implications - The varying sampling and data collection processes between the two countries may have introduced unintended bias to the study. The paper's scope may not have addressed all of the technical, organizational, cultural, and political issues that may have influenced the outcome. Practical implications - Thefindings of the study provide empirical evidence that RFID has become a comprehensive business tool to assist more seamless global SCM. Originality/value - This unique comparative study is a useful contribution for both academicians and practitioners to gain a better understanding of how RFID technology is perceived by firms in different countries. The paper also helps companies improve their RFID strategies in the global market by recognizing different perceptions and approaches to implementing RFID. © Emerald Group Publishing Limited.


Zhao Z.,Enphase Energy | Lai J.-S.,Virginia Polytechnic Institute and State University | Cho Y.,Konkuk University
IEEE Transactions on Industrial Electronics | Year: 2013

Three dual-mode boost-buck-derived inverters with smooth transition between modes have been proposed: 1) boost-full bridge inverter; 2) boost-H5 inverter; 3) boost-dual buck inverter. For the same topologies, in conventional control method, the first stage is needed to boost input voltage to a constant high voltage, and the second stage is for sinusoidal inverting. However, in the proposed three inverters, either buck or boost mode works at a single time, thus, only one switch works at a high switching frequency. In this way, a lot switching loss can be reduced, and moreover, since the voltage across the middle capacitor is smaller than the conventional constant high voltage, the further switching loss mitigation is possible. In order to achieve smooth transition between the two modes, a double-carrier-based sinusoidal pulse width modulation (SPWM) is proposed. Other than this, three advanced modulation methods are proposed: 1) double-carrier with different frequencies; 2) double-carrier with different magnitudes; and 3) double-carrier with different frequencies and magnitudes. Following that, the loss distribution in every component is provided and the California Energy Commission efficiency of these inverters under different input voltage conditions is compared. Finally, the experimental results show the dual-mode double-carrier-based SPWM inverter can improve the efficiency by 2% than the traditional constant dc bus voltage solutions. © 2012 IEEE.


Jung S.,SLAC | Song J.,Konkuk University | Yoon Y.W.,Konkuk University | Yoon Y.W.,Korea Institute for Advanced Study
Journal of High Energy Physics | Year: 2016

Abstract: A hypothetical new scalar resonance, a candidate explanation for the recently observed 750 GeV diphoton excess at the LHC 13 TeV, necessarily interferes with the continuum background gg → γγ. The interference has two considerable effects: (1) enhancing or suppressing diphoton signal rate due to the imaginary-part interference and (2) distorting resonance shape due to the real-part interference. We study them based on the best-fit analysis of two benchmark models: two Higgs doublets with ∼50 GeV width (exhibiting the imaginary-part interference effect) and a singlet scalar with 5 GeV width (exhibiting the real-part one), both extended with vector-like fermions. We find that the resonance contribution can be enhanced by a factor of 2 (1.6) for 3 (6) fb signal rate, or the 68% CL allowed mass region is shifted by O (1) GeV. If the best-fit excess rate decreases in the future data, the interference effects will become more significant. © 2016, The Author(s).


News Article | September 23, 2016
Site: www.materialstoday.com

Graphene nanoribbons dissolved in the biocompatible polymer, polyethylene glycol (PEG), could be used to knit together damaged or even severed spinal cord tissue, thanks to research at Rice University in Texas, USA. Preliminary tests in animals with spinal injury are described in the journal Surgical Neurology International. Graphene nanoribbons were customized for medical use by Rice's William Sikkema, who found that biocompatible nanoribbons with PEG-functionalized edges can form an electrically active network that helps the severed ends of a spinal cord reconnect. "Neurons grow nicely on graphene because it's a conductive surface and it stimulates neuronal growth," explains James Tour. Earlier research has already demonstrated that neurons can grow along a graphene surface. "We're not the only lab that has demonstrated neurons growing on graphene in a Petri dish," Tour adds. "The difference is other labs are commonly experimenting with water-soluble graphene oxide, which is far less conductive than graphene, or non-ribbonized structures of graphene." Tour and his colleagues have developed a method to add polymer chains to graphene nanoribbons that then make it water soluble without disrupting their conductivity. "We're just now starting to see the potential for this in biomedical applications," Tour explains. He adds that ribbonized graphene structures allow for much smaller amounts to be used while preserving a conductive pathway that would ultimately allow bridging of a damaged spinal cord. The team has demonstrated that their material could restore function in a rodent with a severed spinal cord in a procedure performed at Konkuk University in South Korea by co-authors Bae Hwan Lee and C-Yoon Kim. Tour adds that the material reliably allowed motor and sensory neuronal signals to cross the gap 24 hours after complete transection of the spinal cord. The rodent experienced almost complete recovery of motor control after two weeks. This is a major advance over previous work with PEG alone, which gave no recovery of sensory neuronal signals over the same period of time and only 10 percent motor control over four weeks, Tour says. "Our goal is to develop this as a way to address spinal cord injury. We think we're on the right path," he adds. The neurophysiological signs are promising but there now needs to be an analysis of behavior and movement following repair of complete severance. Moreover, tests now need to be carried out in a statistically significant fashion by the behavioral analysis group. The next step will be to see how well the neurophysiological markers of recovery correlate with positive behavioral and locomotive changes. Details of the work are reported in the journal Surgical Neurology International [JM Tour et al., Surg. Neurol. Int. (2016) 7(25), 632 DOI: 10.4103/2152-7806.190475] David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".


News Article | September 20, 2016
Site: www.cemag.us

Graphene nanoribbons customized for medical use by William Sikkema, a Rice graduate student and co-lead author of the paper, are highly soluble in polyethylene glycol (PEG), a biocompatible polymer gel used in surgeries, pharmaceutical products and in other biological applications. When the biocompatible nanoribbons have their edges functionalized with PEG chains and are then further mixed with PEG, they form an electrically active network that helps the severed ends of a spinal cord reconnect. “Neurons grow nicely on graphene because it’s a conductive surface and it stimulates neuronal growth,” Tour says. In experiments at Rice and elsewhere, neurons have been observed growing along graphene. “We’re not the only lab that has demonstrated neurons growing on graphene in a petri dish,” he says. “The difference is other labs are commonly experimenting with water-soluble graphene oxide, which is far less conductive than graphene, or nonribbonized structures of graphene. “We’ve developed a way to add water-solubilizing polymer chains to the edges of our nanoribbons that preserves their conductivity while rendering them soluble, and we’re just now starting to see the potential for this in biomedical applications,” he says. He added that ribbonized graphene structures allow for much smaller amounts to be used while preserving a conductive pathway that bridges the damaged spinal cords. Tour says only 1 percent of Texas-PEG consists of nanoribbons, but that’s enough to form a conductive scaffold through which the spinal cord can reconnect. Texas-PEG succeeded in restoring function in a rodent with a severed spinal cord in a procedure performed at Konkuk University in South Korea by co-authors Bae Hwan Lee and C-Yoon Kim. Tour says the material reliably allowed motor and sensory neuronal signals to cross the gap 24 hours after complete transection of the spinal cord and almost perfect motor control recovery after two weeks. “This is a major advance over previous work with PEG alone, which gave no recovery of sensory neuronal signals over the same period of time and only 10 percent motor control over four weeks,” Tour says. The project began when Sikkema read about work by Italian neurosurgeon Sergio Canavero. Sikkema thought nanoribbons might enhance research that depended on PEG’s ability to promote the fusion of cell membranes by adding electrical conductivity and directional control for neurons as they spanned the gap between sections of the spinal cord. Contact with the doctor led to a collaboration with the South Korean researchers. Tour says Texas-PEG’s potential to help patients with spinal cord injuries is too promising to be minimized. “Our goal is to develop this as a way to address spinal cord injury. We think we’re on the right path,” he says. “This is an exciting neurophysiological analysis following complete severance of a spinal cord,” Tour says. “It is not a behavioral or locomotive study of the subsequent repair. The tangential singular locomotive analysis here is an intriguing marker, but it is not in a statistically significant set of animals. The next phases of the study will highlight the locomotive and behavioral skills with statistical relevance to assess whether these qualities follow the favorable neurophysiology that we recorded here.” Kim, co-primary author of the paper, is a research professor in the Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, South Korea, and a researcher at Seoul National University. Lee is an associate professor of physiology at the Yonsei University College of Medicine, Seoul. Co-authors are In-Kyu Hwang of Konkuk University, Hanseul Oh of Seoul National University and Un Jeng Kim of the Yonsei University College of Medicine. Tour is the T.T. and W.F. Chao Professor of Chemistry as well as a professor of computer science and of materials science and nanoengineering.


News Article | September 20, 2016
Site: www.rdmag.com

The combination of graphene nanoribbons made with a process developed at Rice University and a common polymer could someday be of critical importance to healing damaged spinal cords in people, according to Rice chemist James Tour. The Tour lab has spent a decade working with graphene nanoribbons, starting with the discovery of a chemical process to "unzip" them from multiwalled carbon nanotubes, as revealed in a Nature paper in 2009. Since then, the researchers have used them to enhance materials for the likes of deicers for airplane wings, better batteries and less-permeable containers for natural gas storage. Now their work to develop nanoribbons for medical applications has resulted in a material dubbed Texas-PEG that may help knit damaged or even severed spinal cords. A paper on the results of preliminary animal-model tests appears today in the journal Surgical Neurology International. Graphene nanoribbons customized for medical use by William Sikkema, a Rice graduate student and co-lead author of the paper, are highly soluble in polyethylene glycol (PEG), a biocompatible polymer gel used in surgeries, pharmaceutical products and in other biological applications. When the biocompatible nanoribbons have their edges functionalized with PEG chains and are then further mixed with PEG, they form an electrically active network that helps the severed ends of a spinal cord reconnect. "Neurons grow nicely on graphene because it's a conductive surface and it stimulates neuronal growth," Tour said. In experiments at Rice and elsewhere, neurons have been observed growing along graphene. "We're not the only lab that has demonstrated neurons growing on graphene in a petri dish," he said. "The difference is other labs are commonly experimenting with water-soluble graphene oxide, which is far less conductive than graphene, or nonribbonized structures of graphene. "We've developed a way to add water-solubilizing polymer chains to the edges of our nanoribbons that preserves their conductivity while rendering them soluble, and we're just now starting to see the potential for this in biomedical applications," he said. He added that ribbonized graphene structures allow for much smaller amounts to be used while preserving a conductive pathway that bridges the damaged spinal cords. Tour said only 1 percent of Texas-PEG consists of nanoribbons, but that's enough to form a conductive scaffold through which the spinal cord can reconnect. Texas-PEG succeeded in restoring function in a rodent with a severed spinal cord in a procedure performed at Konkuk University in South Korea by co-authors Bae Hwan Lee and C-Yoon Kim. Tour said the material reliably allowed motor and sensory neuronal signals to cross the gap 24 hours after complete transection of the spinal cord and almost perfect motor control recovery after two weeks. "This is a major advance over previous work with PEG alone, which gave no recovery of sensory neuronal signals over the same period of time and only 10 percent motor control over four weeks," Tour said. The project began when Sikkema read about work by Italian neurosurgeon Sergio Canavero. Sikkema thought nanoribbons might enhance research that depended on PEG's ability to promote the fusion of cell membranes by adding electrical conductivity and directional control for neurons as they spanned the gap between sections of the spinal cord. Contact with the doctor led to a collaboration with the South Korean researchers. Tour said Texas-PEG's potential to help patients with spinal cord injuries is too promising to be minimized. "Our goal is to develop this as a way to address spinal cord injury. We think we're on the right path," he said. "This is an exciting neurophysiological analysis following complete severance of a spinal cord," Tour said. "It is not a behavioral or locomotive study of the subsequent repair. The tangential singular locomotive analysis here is an intriguing marker, but it is not in a statistically significant set of animals. The next phases of the study will highlight the locomotive and behavioral skills with statistical relevance to assess whether these qualities follow the favorable neurophysiology that we recorded here."


News Article | September 21, 2016
Site: www.techtimes.com

Nanotechnology - What You Should Know Graphene - Here's What You Should Know Graphene nanoribbons developed by Rice University through a special process is holding great promise in terms of healing damaged spinal cords of affected people. Researchers were able to demonstrate using Texas-PEG in joining damaged or severed spinal cords at the animal level. Rice University's chemist James Tour is too excited about the potential of Texas-PEG's potential in healing patients with spinal cord injuries. A paper on the preliminary tests was published in the journal Surgical Neurology International. "Our goal is to develop this as a way to address spinal cord injury. We think we're on the right path," Tour said. The graphene nanoribbons was customized for medical use by William Sikkema, a graduate student at Rice University and a co-lead author of the paper. The Texas-PEG recorded its big success story by restoring the failed spinal functions of a rodent with a ruptured spinal cord. The operation was performed by Bae Hwan Lee and C-Yoon Kim at the Konkuk University in South Korea. They are also the co-authors of the paper. In the rodent experiment, Texas-PEG was able to successfully relay the motor and sensory neuronal signals, 24 hours after its complete breakdown from the ruptured spinal cord. Adding to the feat was full motor control recovery after two weeks. The scientists also made Texas-PEG able to conduct electricity by exposing it to highly soluble polyethylene glycol (PEG). Neuron growing along graphene, which has been demonstrated in many other research projects, is possible thanks to graphene's conductive surface property in stimulating neuronal growth. "We're not the only lab that has demonstrated neurons growing on graphene in a petri dish," Tour said. He then explained the difference between their experiments and others. Other labs were experimenting with water-soluble graphene oxide, which poorly conducts electricity if compared to graphene and other non-ribbonized graphene structures. The team went one step ahead and added water-solubilizing polymer chain to the edges of nanoribbons to achieve solubility, yet maintain the material's conductivity. Tour said the innovation was a game changer and has expanded the use to other biomedical applications. Tour called the new breakthrough as significant and a major advance over previous work that had a narrow focus with PEG. Also, the previous work did not result in drastic recovery in terms of sensory neuronal signals during the same period as in the new rodent experiment. Moreover, motor control recovery is just at 10 percent. Meanwhile, efforts are progressing on expanding the medical use of graphene in many centers. In Italy, a team of scientists is harping on the antifungal action and antibacterial properties of graphene oxide, which is a carbon-derived compound. They have reported success in using them as a coating for catheters and medical tools as a way to reduce infections and cut down the use of antibiotics. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | October 26, 2016
Site: www.newscientist.com

Video footage seen by New Scientist appears to show a dog walking three weeks after its spinal cord was almost completely severed. Italian neurosurgeon Sergio Canavero says the technique used to treat the dog will make a human head transplant possible next year. Canavero came to fame in 2015, when he claimed that the major hurdles to completing a head transplant are now surmountable. The idea is that someone paralysed from the neck down, for example, could have their head connected to the body of someone who is brain dead, restoring their ability to move (see box, below). However, papers published today detailing the spinal cord repair technique applied to the dog have prompted other scientists to express concerns over the work. “These papers do not support moving forward in humans,” says Jerry Silver, a neuroscientist at Case Western Reserve University in Ohio. To fuse two ends of a spinal cord – either in someone who has broken their spine or to connect a transplanted head to a donor body – the ends of thousands of neurons need to meet across the join. Bunched together like strands of spaghetti, if these neurons don’t touch, they will grow past each other and never form the electricity-conducting pathways that send nerve impulses through the body. In a series of three papers, all co-edited by Canavero for the journal Surgical Neurology International, researchers in South Korea and the US claim that a chemical called polyethylene glycol, or PEG, may help reconnect a severed spinal cord. C-Yoon Kim at Konkuk University in Seoul and his team – who have been working closely with Canavero – severed the spinal cord of 16 mice. They then injected PEG into the gap between the cut ends of the spinal cord in half of the mice, while the rest were injected with saline. After four weeks, they report that five of the eight mice in the PEG group had regained some ability to move, compared with none of the control group. The other three PEG-treated mice died, as did all those in the control group. Meanwhile, a team at Rice University in Houston, Texas, has been working to develop a better version of PEG. Hearing about Canavero’s plans to use the solution in a human head transplant, the team believed it could improve it by adding graphene nanoribbons – an electrically conductive material that acts as a scaffold that neurons can grow along. “My motivation is spinal cord repair. If this works, it’s going to have huge ramifications for spinal injuries,” says James Tour, who is part of the Rice team. “But we thought, if you’re going to be working towards a head transplant, you’re going to need this, so let us help you.” “Read more: 6 things you’re dying to ask about head transplants” PEG encourages the fat in cell membranes to mesh, bringing cells together – a process that may be enhanced by the nanoribbons, which are thought to provide scaffolding that encourages neurons to grow towards each other and connect. Tour says they do this in two ways: they are able to conduct electrical current, which helps neurons grow, and neurons seem to preferentially grow along this scaffolding, which helps them to meet and fuse together. The South Korean team have nicknamed Tour’s enhanced solution Texas-PEG, and injected it into five rats’ spinal cords immediately after they had been severed. Five control rats were given saline instead. The following day, the team stimulated the rats’ spinal cords to see if any electrical activity could pass along it. According to the team’s paper, a small amount of electrical signals were present in the Texas-PEG group, but completely absent in the controls. The group state that a flood in the lab subsequently killed four of the five rats that had been treated with Texas-PEG. Two days after surgery, the remaining rat is reported to have shown slight voluntary movement in all four paws, and a week later it was able to stand, but had difficulty balancing. After two weeks, the team says the rat could walk, stand up on his hind limbs and feed itself. “No recovery was observed in the controls,” says Kim. In a final experiment, the South Korean team tested the original PEG in a dog immediately after it was given a near-complete cervical (neck) spinal lesion. Visual inspection suggested more than 90 per cent of its spinal cord had been severed – similar to what is seen in people who receive stab wounds to the spinal cord. The following day, the dog was completely paralysed, but after three days, the team reports minimal movement in all four limbs. After two weeks, the dog was able to drag its hind limbs by its torso and forelimbs, and during the third week, it was able to walk. The team claims that the dog began to grab objects, wag its tail and resume a normal life. There was no control in the experiment. New Scientist contacted more than 10 experts about these studies and the videos, but most were unwilling to comment publicly on the research. Those who have commented say they have serious concerns about the reported results.  “The dog is a case report, and you can’t learn very much from a single animal without controls,” says Silver. “They claim they cut the cervical cord 90 per cent but there’s no evidence of that in the paper, just some crude pictures.” “Read more: First human head transplant could happen in two years” Silver would prefer to see histology – microscopic tissue analysis – to confirm the dog’s spinal cord really was severely damaged before it recovered. As for the Texas-PEG paper, he says there is too little data. “You don’t report that four of your five treated animals drowned. You start again and increase your sample size,” says Silver. Kim emphasises that his team’s experiments were proof of principle case studies, but says that “when combined, [they] confirm that a severed cord can be reconstructed”. The teams says its next paper will provide histological evidence confirming how damaged the animals’ spines were. As for Canavero’s goal to conduct the first human head transplant soon, medical ethicist Arthur Caplan at New York University says the latest studies suggest this procedure is still some years away. “This work would put them about three or four years from repairing a spinal cord in humans,” he says. “It would put them maybe seven or eight from trying anything like a head transplant.” Sergio Canavero first proposed attempting a human head transplant in 2013. He wants to use the surgery to extend the lives of people whose muscles and nerves have degenerated or whose organs are riddled with cancer. But there are many hurdles, such as fusing the spinal cord (see main story) and preventing the body’s immune system from rejecting the head. The procedure will involve cooling both the head and the body it is to be moved to, to extend the time their cells can survive without oxygen. The tissue around the neck would then be dissected and the major blood vessels linked using tiny tubes, before the spinal cords of each person are cut. The head would then be moved onto the donor body, and the ends of their spinal cords fused together using PEG. Next, the muscles and blood supply would be sutured. The recipient would be kept in a coma for three or four weeks to prevent movement. Implanted electrodes would be used to provide regular electrical stimulation to the spinal cord, because research suggests this can strengthen new nerve connections. Canavero still thinks it could be possible to perform the first human head transplant by the end of 2017, depending upon finding a suitable donor. Several people have said they would like to volunteer to have their heads attached to a different body, while a hospital in Vietnam is reportedly keen to host the first surgery. Read more: Head transplant carried out on monkey, claims maverick surgeon


News Article | September 26, 2016
Site: www.materialstoday.com

These microscope images show graphene nanoribbons unzipped from multiwalled carbon nanotubes. When their edges are modified with PEG, the nanoribbons provide conductive surfaces for neuronal growth. Image: Tour Group/Rice University.A combination of graphene nanoribbons made with a process developed at Rice University and a common polymer could someday be of critical importance for healing damaged spinal cords in people, according to Rice chemist James Tour. The Tour lab has spent a decade working with graphene nanoribbons, starting with the discovery of a chemical process to ‘unzip’ them from multiwalled carbon nanotubes, as revealed in a Nature paper in 2009. Since then, the researchers have used them to enhance materials for the likes of deicers for airplane wings (see New graphene coating helps put ice in a spin), better batteries and less-permeable containers for natural gas storage. Now their work to develop nanoribbons for medical applications has resulted in a material dubbed Texas-PEG that may help knit damaged or even severed spinal cords. A paper on the results of preliminary animal-model tests is published in Surgical Neurology International. Graphene nanoribbons customized for medical use by William Sikkema, a Rice graduate student and co-lead author of the paper, are highly soluble in polyethylene glycol (PEG), a biocompatible polymer gel used in surgeries, pharmaceutical products and other biological applications. When the biocompatible nanoribbons have their edges functionalized with PEG chains and are then further mixed with PEG, they form an electrically active network that can help the severed ends of a spinal cord to reconnect. “Neurons grow nicely on graphene because it’s a conductive surface and it stimulates neuronal growth,” Tour said. In experiments at Rice and elsewhere, neurons have been observed growing along graphene. “We’re not the only lab that has demonstrated neurons growing on graphene in a petri dish,” he said. “The difference is other labs are commonly experimenting with water-soluble graphene oxide, which is far less conductive than graphene, or nonribbonized structures of graphene. “We’ve developed a way to add water-solubilizing polymer chains to the edges of our nanoribbons that preserves their conductivity while rendering them soluble, and we’re just now starting to see the potential for this in biomedical applications,” he said. He added that ribbonized graphene structures allow for much smaller amounts to be used while preserving a conductive pathway that bridges the damaged spinal cords. According to Tour, although only 1% of Texas-PEG consists of nanoribbons, that’s enough to form a conductive scaffold through which the spinal cord can reconnect. Texas-PEG succeeded in restoring function in a rodent with a severed spinal cord in a procedure performed at Konkuk University in South Korea by co-authors Bae Hwan Lee and C-Yoon Kim. The material reliably allowed motor and sensory neuronal signals to cross the gap 24 hours after complete transection of the spinal cord, leading to almost perfect motor control recovery after two weeks. “This is a major advance over previous work with PEG alone, which gave no recovery of sensory neuronal signals over the same period of time and only 10% motor control over four weeks,” Tour said. The project began when Sikkema read about work by Italian neurosurgeon Sergio Canavero. Sikkema thought nanoribbons might help to enhance PEG’s ability to promote the fusion of cell membranes by adding electrical conductivity and directional control for neurons as they grow to span the gap between sections of the spinal cord. Contact with the doctor led to a collaboration with the South Korean researchers. Tour said Texas-PEG’s potential to help patients with spinal cord injuries is too promising to be minimized. “Our goal is to develop this as a way to address spinal cord injury. We think we’re on the right path,” he said. “This is an exciting neurophysiological analysis following complete severance of a spinal cord,” Tour said. “It is not a behavioral or locomotive study of the subsequent repair. The tangential singular locomotive analysis here is an intriguing marker, but it is not in a statistically significant set of animals. The next phases of the study will highlight the locomotive and behavioral skills with statistical relevance to assess whether these qualities follow the favorable neurophysiology that we recorded here.” This story is adapted from material from Rice University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.


Home > Press > Graphene nanoribbons show promise for healing spinal injuries: Rice University scientists develop Texas-PEG to help knit severed, damaged spinal cords Abstract: The combination of graphene nanoribbons made with a process developed at Rice University and a common polymer could someday be of critical importance to healing damaged spinal cords in people, according to Rice chemist James Tour. The Tour lab has spent a decade working with graphene nanoribbons, starting with the discovery of a chemical process to "unzip" them from multiwalled carbon nanotubes, as revealed in a Nature paper in 2009. Since then, the researchers have used them to enhance materials for the likes of deicers for airplane wings, better batteries and less-permeable containers for natural gas storage. Now their work to develop nanoribbons for medical applications has resulted in a material dubbed Texas-PEG that may help knit damaged or even severed spinal cords. A paper on the results of preliminary animal-model tests appears today in the journal Surgical Neurology International. Graphene nanoribbons customized for medical use by William Sikkema, a Rice graduate student and co-lead author of the paper, are highly soluble in polyethylene glycol (PEG), a biocompatible polymer gel used in surgeries, pharmaceutical products and in other biological applications. When the biocompatible nanoribbons have their edges functionalized with PEG chains and are then further mixed with PEG, they form an electrically active network that helps the severed ends of a spinal cord reconnect. "Neurons grow nicely on graphene because it's a conductive surface and it stimulates neuronal growth," Tour said. In experiments at Rice and elsewhere, neurons have been observed growing along graphene. "We're not the only lab that has demonstrated neurons growing on graphene in a petri dish," he said. "The difference is other labs are commonly experimenting with water-soluble graphene oxide, which is far less conductive than graphene, or nonribbonized structures of graphene. "We've developed a way to add water-solubilizing polymer chains to the edges of our nanoribbons that preserves their conductivity while rendering them soluble, and we're just now starting to see the potential for this in biomedical applications," he said. He added that ribbonized graphene structures allow for much smaller amounts to be used while preserving a conductive pathway that bridges the damaged spinal cords. Tour said only 1 percent of Texas-PEG consists of nanoribbons, but that's enough to form a conductive scaffold through which the spinal cord can reconnect. Texas-PEG succeeded in restoring function in a rodent with a severed spinal cord in a procedure performed at Konkuk University in South Korea by co-authors Bae Hwan Lee and C-Yoon Kim. Tour said the material reliably allowed motor and sensory neuronal signals to cross the gap 24 hours after complete transection of the spinal cord and almost perfect motor control recovery after two weeks. "This is a major advance over previous work with PEG alone, which gave no recovery of sensory neuronal signals over the same period of time and only 10 percent motor control over four weeks," Tour said. The project began when Sikkema read about work by Italian neurosurgeon Sergio Canavero. Sikkema thought nanoribbons might enhance research that depended on PEG's ability to promote the fusion of cell membranes by adding electrical conductivity and directional control for neurons as they spanned the gap between sections of the spinal cord. Contact with the doctor led to a collaboration with the South Korean researchers. Tour said Texas-PEG's potential to help patients with spinal cord injuries is too promising to be minimized. "Our goal is to develop this as a way to address spinal cord injury. We think we're on the right path," he said. "This is an exciting neurophysiological analysis following complete severance of a spinal cord," Tour said. "It is not a behavioral or locomotive study of the subsequent repair. The tangential singular locomotive analysis here is an intriguing marker, but it is not in a statistically significant set of animals. The next phases of the study will highlight the locomotive and behavioral skills with statistical relevance to assess whether these qualities follow the favorable neurophysiology that we recorded here." Kim, co-primary author of the paper, is a research professor in the Department of Stem Cell Biology, School of Medicine, Konkuk University, Seoul, South Korea, and a researcher at Seoul National University. Lee is an associate professor of physiology at the Yonsei University College of Medicine, Seoul. Co-authors are In-Kyu Hwang of Konkuk University, Hanseul Oh of Seoul National University and Un Jeng Kim of the Yonsei University College of Medicine. Tour is the T.T. and W.F. Chao Professor of Chemistry as well as a professor of computer science and of materials science and nanoengineering. About Rice University Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice’s undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance. To read “What they’re saying about Rice,” go to tinyurl.com/RiceUniversityoverview. Follow Rice News and Media Relations via Twitter @RiceUNews Related For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Background: Food allergies are important etiologic factors in atopic dermatitis. CD19 is a B-cell-specific cell-surface molecule, with a critical role in B-cell activation. Recently, B cells showed independent two subpopulations as CD19hi and CD19low. The allergen-specific responses of the CD19high and CD19low B-cell subpopulations were investigated in patients with non-IgE-mediated food allergy. Methods: Five milk-allergic subjects and eight milk-tolerant subjects were selected by a double-blind placebo-controlled food challenge. Peripheral blood mononuclear cells (PBMCs) were stimulated in vitro with casein or ovalbumin and stained with monoclonal antibodies to distinguish the B-cell subsets. Results: After allergen stimulation, CD19high B cells increased in the number and the fraction in PBMCs in the milk-tolerant group, whereas those remained unchanged in the milk-allergic group. These responses were constant, regardless of the kind of food allergen (milk or egg). The resulting CD19high/CD19low B-cell ratio increased markedly in the milk-tolerant group after allergen stimulation, but was unchanged in the milk-allergic group. IL-10, IL-17, IL-32 and TGF-p-producing regulatory B cells and Foxp3-expressing regulatory B cells were identified predominantly on CD19 low and CD5(+) B cells. Conclusions: The response of the CD19high B-cell subpopulation to allergen stimulation is decisive for immune tolerance of non-IgE-mediated food allergy in atopic dermatitis. CD19 high and CD5(+) B cells dominantly produce cytokines and express Foxp3. Especially, IL-17 and IL-32 expressing B cells (Br17 & Br32) are present. The exact immunological role of CD19 and cytokines including IL-17 and IL-32 around B cells in immune tolerance requires further investigation. © 2012 Bentham Science Publishers.


Jeong B.R.,Gyeongsang National University | Sivanesan I.,Gyeongsang National University | Sivanesan I.,Konkuk University
Plant Cell, Tissue and Organ Culture | Year: 2015

Effects of plant growth regulators, light quality and sucrose on direct adventitious shoot regeneration, in vitro flowering and fruiting of Scrophularia takesimensis were investigated. The highest mean number of shoots per leaf (23.4), petiole (17.2) and stem (20.3) explants was obtained on Murashige and Skoog (MS) medium fortified with 2.0 mg l−1 BA and 1.0 mg l−1 IAA under white fluorescent light (WFL). Red light emitting diodes (LED) gave better shoot growth followed by WFL and blue LED. However, red LED treatment decreased the number of roots and induced callus at the base of shoot. The highest number of roots per shoot (9.2) and a maximum root length (8.9 cm) were obtained when the cultures were maintained under WFL. Somaclonal variation was observed when the shoot buds were cultured on the modified MS medium containing 1.0 mg l−1 IBA. The variant had variegated leaves in comparison with those of normal plantlets. The greatest frequency of flower induction (96.8 %) was obtained when the shoots were cultured on the modified MS medium containing 6.0 % (w/v) sucrose for 45 days under blue LED. The in vitro developed flowers self-fertilized and formed fruits. The culture media and environment had a positive effect on the content of phenolic compounds. Harpagoside content was high in seeds and low in shoots developed in MS medium containing BA. Among the light sources, shoots maintained under blue LED found to be best for harpagoside production (4.9 mg g−1) followed by WFL (3.3 mg g−1) and red LED (2.7 mg g−1). In vitro regenerated shoots had higher capacity to detoxify DPPH free radicals than field-grown plant samples. © 2015, Springer Science+Business Media Dordrecht.


Lim Y.,Konkuk University | Koh D.,Dongduk Women's University
Acta Crystallographica Section E: Structure Reports Online | Year: 2013

In the title molecule, C18H18O4, the dihedral angle between the benzene rings is 52.52 (7)°. The C=C bond of the central enone group adopts a trans conformation. The relative conformation of the two double bonds in the enone group is s-transoid. In the crystal, molecules are linked by pairs of weak C-H⋯O hydrogen bonds, forming inversion dimers.


Lee J.,Konkuk University | Lee J.,Plant Genomics and Breeding Institute | Koh H.-J.,Plant Genomics and Breeding Institute
Proteome Science | Year: 2011

Background: Although a great deal of rice proteomic research has been conducted, there are relatively few studies specifically addressing the rice grain proteome. The existing rice grain proteomic researches have focused on the identification of differentially expressed proteins or monitoring protein expression patterns during grain filling stages.Results: Proteins were extracted from rice grains 10, 20, and 30 days after flowering, as well as from fully mature grains. By merging all of the identified proteins in this study, we identified 4,172 non-redundant proteins with a wide range of molecular weights (from 5.2 kDa to 611 kDa) and pI values (from pH 2.9 to pH 12.6). A Genome Ontology category enrichment analysis for the 4,172 proteins revealed that 52 categories were enriched, including the carbohydrate metabolic process, transport, localization, lipid metabolic process, and secondary metabolic process. The relative abundances of the 1,784 reproducibly identified proteins were compared to detect 484 differentially expressed proteins during rice grain development. Clustering analysis and Genome Ontology category enrichment analysis revealed that proteins involved in the metabolic process were enriched through all stages of development, suggesting that proteome changes occurred even in the desiccation phase. Interestingly, enrichments of proteins involved in protein folding were detected in the desiccation phase and in fully mature grain.Conclusion: This is the first report conducting comprehensive identification of rice grain proteins. With a label free shotgun proteomic approach, we identified large number of rice grain proteins and compared the expression patterns of reproducibly identified proteins during rice grain development. Clustering analysis, Genome Ontology category enrichment analysis, and the analysis of composite expression profiles revealed dynamic changes of metabolisms during rice grain development. Interestingly, we detected that proteins involved in glycolysis, TCA-cycle, lipid metabolism, and proteolysis accumulated at higher levels in fully mature grain compared to grain developing stages, suggesting that the accumulation of these proteins during the desiccation stage may be associated with the preparation of proteins required in germination. © 2011 Lee and Koh; licensee BioMed Central Ltd.


Hur S.J.,Gyeongsang National University | Lim B.O.,Konkuk University | Decker E.A.,University of Massachusetts Amherst | McClements D.J.,University of Massachusetts Amherst
Food Chemistry | Year: 2011

In vitro digestion models are widely used to study the structural changes, digestibility, and release of food components under simulated gastrointestinal conditions. However, the results of in vitro digestion models are often different to those found using in vivo models because of the difficulties in accurately simulating the highly complex physicochemical and physiological events occurring in animal and human digestive tracts. This paper provides an overview of current trends in the development and utilisation of in vitro digestion models for foods, as well as information that can be used to develop improved digestion models. Our survey of in vitro digestion models found that the most predominant food samples tested were plants, meats, fish, dairy, and emulsion-based foods. The most frequently used biological molecules included in the digestion models were digestive enzymes (pancreatin, pepsin, trypsin, chymotrypsin, peptidase, α-amylase, and lipase), bile salts, and mucin. In all the in vitro digestion models surveyed, the digestion temperature was 37°C although varying types and concentrations of enzymes were utilised. With regard to digestion times, 2. h (the stomach, small intestine, and large intestine each) was predominantly employed. This survey enhances the understanding of in vitro digestion models and provides indications for the development of improved in vitro digestion models for foods or pharmaceuticals. © 2010 Elsevier Ltd.


Kadam A.A.,Shivaji University | Telke A.A.,Gyeongsang National University | Jagtap S.S.,Konkuk University | Govindwar S.P.,Shivaji University
Journal of Hazardous Materials | Year: 2011

The objective of this study was to develop consortium using Pseudomonas sp. SUK1 and Aspergillus ochraceus NCIM-1146 to decolorize adsorbed dyes from textile effluent wastewater under solid state fermentation. Among various agricultural wastes rice bran showed dye adsorption up to 90, 62 and 80% from textile dye reactive navy blue HE2R (RNB HE2R) solution, mixture of textile dyes and textile industry wastewater, respectively. Pseudomonas sp. SUK1 and A. ochraceus NCIM-1146 showed 62 and 38% decolorization of RNB HE2R adsorbed on rice bran in 24. h under solid state fermentation. However, the consortium of Pseudomonas sp. SUK1 and A. ochraceus NCIM-1146 (consortium-PA) showed 80% decolorization in 24. h. The consortium-PA showed effective ADMI removal ratio of adsorbed dyes from textile industry wastewater (77%), mixture of textile dyes (82%) and chemical precipitate of textile dye effluent (CPTDE) (86%). Secretion of extracellular enzymes such as laccase, azoreductase, tyrosinase and NADH-DCIP reductase and their significant induction in the presence of adsorbed dye suggests their role in the decolorization of RNB HE2R. GCMS and HPLC analysis of product suggests the different fates of biodegradation of RNB HE2R when used Pseudomonas sp. SUK1, A. ochraceus NCIM-1146 and consortium PA. © 2011 Elsevier B.V.


Shin S.Y.,Konkuk University | Lee J.M.,Konkuk University | Lee M.S.,Konkuk University | Koh D.,Dongduk Women's University | And 3 more authors.
Clinical Cancer Research | Year: 2014

Purpose: The selective killing of tumor cells is an important strategy for cancer therapeutics. The aim of this study was to develop a novel antitumor agent that is safe for normal cells with the ability to selectively target cancer cells. Experimental Design: On the basis of quantitative structure-activity relationship, we synthesized a novel polyphenol conjugate (E)-3-(3,5-dimethoxyphenyl)-1-(2-methoxyphenyl)prop-2-en-1-one (DPP-23). We evaluated the effect of DPP-23 on proliferation, cell cycle, and apoptosis in various tumor cells. We also assessed molecular targets of DPP-23 using genome-wide expression profiling by DNA microarray and real-time PCR array systems. Results: DPP-23 effectively inhibited the growth of cancer cells in vitro and in vivo (xenografts in Balb/c nude mice). At a molecular level, DPP-23 targeted the unfolded protein response (UPR) in the endoplasmic reticulum (ER) through the production of reactive oxygen species (ROS) in cancer cells, but not in normal cells, resulting in selective killing of tumor cells via caspase-dependent apoptosis. Conclusions: The selective generation of ROS in cancer cells could be an attractive strategy for the selective killing of cancer cells, while maintaining negligible cytotoxicity to normal cells. DPP-23 represents a promising novel therapeutic agent for the selective production of ROS in cancer cells. ©2014 AACR.


Lee J.M.,Konkuk University | Lee M.S.,Konkuk University | Koh D.,Dongduk Women's University | Lee Y.H.,Konkuk University | And 2 more authors.
Cancer Letters | Year: 2014

Methoxylated chalcones exert antitumor activities. In the present study, we characterized the cytotoxicity of methylated chalcone derivatives against human colon cancer cells. We synthesized a group of methoxychalcones and explored the molecular mechanisms underlying inhibition of tumor growth by these materials. A new synthetic methoxychalcone, 2'-hydroxy-2,4,6-trimethoxy-5',6'-naphthochalcone (named HMNC-74), most effectively inhibited the clonogenicity of SW620 colon cancer cells. Mechanistically, HMNC-74 triggered cell cycle arrest at G2/M phase, followed by an increase in apoptotic cell death. Our results indicate that the cytotoxicity of the novel compound HMNC-74 involves the disruption of microtubular networks. © 2014 Elsevier Ireland Ltd.


Lim Y.C.,Konkuk University | Koo B.S.,Chungnam National University
Oral Oncology | Year: 2012

Skip metastasis, referred to as leaping metastasis to the lateral neck without associated lymphadenopathy in the central compartment (level VI), can occur in patients with papillary thyroid carcinoma (PTC). However, there have been few studies on its predictive value in PTC patients. We reviewed the medical records of 90 patients who underwent simultaneous central and lateral neck lymph node dissection for the primary treatment of lymph node metastasis in the lateral neck of PTC patients. No patient was suspected of having metastasis in the central compartment by preoperative imaging study. The frequency of skip metastasis to the lateral neck compartment without central neck metastasis was 19% (17/90). The number of metastatic lymph nodes dissected in the lateral neck of patients with and without skip metastasis was 5.1 ± 2.7 and 9.5 ± 2.6, respectively (P < 0.001). Skip metastasis was closely associated with significantly fewer lymphovascular invasion (P = 0.009) and extracapsular spread (P = 0.035). Skip metastasis can occur significantly frequently in PTC patients. The presence of lymphovascular invasion, extracapsular spread, and number of positive lymph nodes dissected were inversely correlated with skip metastasis. © 2011 Elsevier Ltd. All rights reserved.


Chang S.,Konkuk University | Kang S.K.,Institute of Convergence Fundamental Studies | Lee J.-P.,Institute of Convergence Fundamental Studies | Lee K.Y.,Gyeongsang National University | And 2 more authors.
Journal of High Energy Physics | Year: 2013

A new boson of mass roughly 125 GeV has been recently reported by the ATLAS and CMS collaborations. Although its signals in various decay modes resemble those of the standard model (SM) Higgs boson, observed are the combinations of entangled information about the production, decay rates and total decay width of the new boson. In addition, some decay channels show non-negligible deviation from the SM expectation, such as the 2σ excess in the diphoton channel. In the four types (I, II, X and Y) of two Higgs doublet models, we perform the global χ 2 fit in three scenarios: (i) the new boson is the light CP-even Higgs boson h 0; (ii) it is the heavy CP-even Higgs boson H 0; (iii) the signals are from the degenerate state of h 0 and the pseudoscalar A 0. Considering other phenomenological constraints such as flavor physics, electroweak precision data, and the LEP search for the Higgs boson, we find that the first scenarios in Type II provides the best fit. And the other models are also as good as the SM in explaining the LHC Higgs data. © 2013 SISSA, Trieste, Italy.


Yoon T.J.,Yuhan University | Koppula S.,Konkuk University | Lee K.H.,Konkuk University
Anti-Cancer Agents in Medicinal Chemistry | Year: 2013

Beta-glucans (β-glucans), naturally occurring polysaccharides, are present as constituents of the cell wall of cereal grains, mushrooms, algae, or microbes including bacteria, fungi, and yeast. Since Pillemer et al. first prepared and investigated zymosan in the 1940s and others followed with the investigation of β-glucans in the 1960s and 1970s, researchers have well established the significant role of β-glucans on the immune system relative to cancer treatment, infection immunity, and restoration of damaged bone marrow. However, information on their biological role in anti-metastatic activity remains limited. As an immunomodulating agent, β-glucan acts through the activation of innate immune cells such as macrophages, dendritic cells, granulocytes, and natural killer cells. This activation triggers the responses of adaptive immune cells such as CD4+ or CD8+ T cells and B cells, resulting in the inhibition of tumor growth and metastasis. Reports have shown that β-glucans exert multiple effects on cancer cells and cancer prevention. However the mechanisms of their actions appear complex due to differences in source, chemical structure, insufficiently defined preparation, and molecular weight, hence the inconsistent and often contradictory results obtained. This review is focused on the potential of β-glucans as anti-metastatic agents and the known mechanisms underlying their biological effects. © 2013 Bentham Science Publishers.


Jung M.Y.,Korea University | Son M.H.,Korea University | Kim S.H.,Konkuk University | Cho D.,Sookmyung Womens University | Kim T.S.,Korea University
Journal of Immunology | Year: 2011

IL-32, a newly described multifunctional cytokine, has been associated with a variety of inflammatory diseases, including rheumatoid arthritis, vasculitis, and Crohn's disease. In this study, we investigated the immunomodulatory effects of IL-32γ on bone marrow-derived dendritic cell (DC)-driven Th responses and analyzed the underlying signaling events. IL-32γ-treated DCs exhibited upregulated expression of cell-surface molecules and proinflammatory cytokines associated with DC maturation and activation. In particular, IL-32γ treatment significantly increased production of IL-12 and IL-6 in DCs, which are known as Th1- and Th17-polarizing cytokines, respectively. This increased production was inhibited by the addition of specific inhibitors of the activities of phospholipase C (PLC), JNK, and NF-κB. IL-32γ treatment increased the phosphorylation of JNK and the degradation of both IκBα and IκBβ in DCs, as well as NF-κB binding activity to the κB site. The PLC inhibitor suppressed NFκB DNA binding activity and JNK phosphorylation increased by IL-32γ treatment, thereby indicating that IL-32γ induced IL-12 and IL-6 production in DCs via a PLC/JNK/NF-κB signaling pathway. Importantly, IL-32γ- stimulated DCs significantly induced both Th1 and Th17 responses when cocultured with CD4+ T cells. The addition of a neutralizing anti-IL-12 mAb abolished the secretion of IFN-γ in a dose-dependent manner; additionally, the blockage of IL-1β and IL-6, but not of IL-21 or IL-23p19, profoundly inhibited IL-32γ-induced IL-17 production. These results demonstrated that IL-32γ could effectively induce the maturation and activation of immature DCs, leading to enhanced Th1 and Th17 responses as the result of increased IL-12 and IL-6 production in DCs. Copyright © 2011 by The American Association of Immunologists, Inc.


Chang J.,National Tsing Hua University | Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lu C.-T.,National Tsing Hua University | Yuan T.-C.,Academia Sinica, Taiwan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

More evidence has now been collected at the Large Hadron Collider suggesting the new 125-126 GeV boson is likely the long-sought Higgs boson in the standard model. One pressing question theorists continue to ask is whether this Higgs boson is a lone player responsible for the full electroweak symmetry breaking. Current data still allow room for additional Higgs bosons or some other UV physics that may play a partial role in electroweak symmetry breaking as well. We use the WW scattering to investigate such a possibility, using the two-Higgs-doublet model as a prototype. The WW scattering becomes strong when the extra Higgs bosons are very heavy. We study the sensitivity of these strong WW scattering signals at the 13 TeV Large Hadron Collider. © 2013 American Physical Society.


Chang J.,National Tsing Hua University | Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Tseng P.-Y.,National Tsing Hua University | Yuan T.-C.,Academia Sinica, Taiwan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The current Large Hadron Collider data indicate that the newly observed resonance has the WW and ZZ modes consistent with the standard model Higgs boson, while the γγ mode is about 1.2-2 times that of the standard model prediction and the tau-pair mode is suppressed. If this pattern persists in the upcoming data, it would be a sign for physics beyond the standard model. In the type II two-Higgs-doublet model, it is the region where sina α≈0 and a moderately large tana β=10-20 that the lighter CP-even Higgs boson can accommodate the current data. We note that in this region the heavier CP-even Higgs boson must have a large decay branching ratio into tau pairs. We find that this heavier Higgs boson can be observable in the associated production with a bb̄ pair and through the decay into a tau pair. © 2013 American Physical Society.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Lu C.-T.,National Tsing Hua University | Yuan T.-C.,Academia Sinica, Taiwan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Motivated by the excess in the diphoton production rate of the Higgs boson at the Large Hadron Collider (LHC), we investigate the possibility that one of the CP-even Higgs bosons of the extra U(1) extended minimal supersymmetric standard model can give a consistent result. We scan the parameter space for a standard-model-like Higgs boson such that the mass is in the range of 124-127 GeV and the production rate σB of the WW*, ZZ* modes is consistent with the standard model (SM) values, while that of γγ is enhanced relative to the SM value. We find that the SM-like Higgs boson is mostly the lightest CP-even Higgs boson and it has a strong mixing with the second lightest one, which is largely singletlike. The implications on Zγ production rate and properties of the other Higgs bosons are also studied. © 2013 American Physical Society.


Son A.R.,Konkuk University | Hyun Y.,Farm Story Dodram B and F | Htoo J.K.,Evonik Industries | Kim B.G.,Konkuk University
Animal Feed Science and Technology | Year: 2014

An experiment was conducted to determine the coefficient of ileal apparent digestibility (CIAD) and the coefficient of ileal standardized digestibility (CISD) of crude protein (CP) and amino acids (AA) in copra expellers (CE) and palm kernel expellers (PKE) by pigs. Six boars fitted with a T-cannula in the distal ileum with an initial body weight of 65.2. ±. 5.4. kg were individually housed in pens equipped with a feeder and a nipple drinker. A replicated 3. ×. 3 Latin square design was employed with 3 dietary treatments, 3 periods, and 6 animals. Two experimental diets were prepared to contain 400. g/kg of CE or PKE as the sole source of nitrogen. A nitrogen-free diet was also prepared to estimate the basal ileal endogenous loss of CP and AA. All diets contained 5. g/kg chromic oxide as an indigestible index. The CIAD of CP in CE was greater (P=0.002) than in PKE (0.294 vs. 0.051). The values for the CIAD of all indispensable AA except histidine and lysine in CE were also greater (P<0.05) than in PKE. The CISD of CP in CE was greater (P=0.014) than in PKE (0.676 vs. 0.528). The values for the CISD of all indispensable AA except histidine, isoleucine, and lysine in CE were greater (P<0.05) than in PKE. In conclusion, the digestibility of CP and most AA in CE was greater than in PKE. © 2013 Elsevier B.V.


Hong S.,Konkuk University | Choi T.,Sejong University | Jeon J.H.,Konkuk University | Kim Y.,Sungkyunkwan University | And 8 more authors.
Advanced Materials | Year: 2013

Comparison between piezoelectric force microscopy images and current-voltage data consecutively obtained using conductive atomic force microscopy below transition voltages for a highly oriented ferroelectric BiFeO3 nano-island confirms that ferroelectric polarization reversal induces transitions of forward-direction, and thus down- and up-polarization is accompanied by positive- and negative-forward diode-like behavior, respectively. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kim S.,Korea University | Lee J.-H.,Sungkyunkwan University | Lee J.,Ewha Womans University | Kim S.-W.,Sungkyunkwan University | And 5 more authors.
Journal of the American Chemical Society | Year: 2013

We report the synthesis of KNbO3 nanowires (NWs) with a monoclinic phase, a phase not observed in bulk KNbO3 materials. The monoclinic NWs can be synthesized via a hydrothermal method using metallic Nb as a precursor. The NWs are metastable, and thermal treatment at ∼450 C changed the monoclinic phase into the orthorhombic phase, which is the most stable phase of KNbO3 at room temperature. Furthermore, we fabricated energy-harvesting nanogenerators by vertically aligning the NWs on SrTiO 3 substrates. The monoclinic NWs showed significantly better energy conversion characteristics than orthorhombic NWs. Moreover, the frequency-doubling efficiency of the monoclinic NWs was ∼3 times higher than that of orthorhombic NWs. This work may contribute to the synthesis of materials with new crystalline structures and hence improve the properties of the materials for various applications. © 2012 American Chemical Society.


Yoon J.-R.,Veterans Health Service Medical Center | Oh K.-J.,Konkuk University | Wang J.H.,Sungkyunkwan University | Yang J.-H.,Veterans Health Service Medical Center
Knee Surgery, Sports Traumatology, Arthroscopy | Year: 2015

Purpose: In vivo comparative gap measurements were performed in three different patella positions (reduced, subluxated and everted) using offset-type-force-controlled-spreader-system. Methods: Prospectively, 50 knees were operated by total knee arthroplasty using a navigation-assisted gap-balancing technique. The offset-type-force-controlled-spreader-system was used for gap measurements. This commercially available instrument allows controllable tension in patella-reduced position. The mediolateral gaps of knee extension (0°) and flexion (90°) angle were recorded in three different patella positions; reduced, subluxated and everted. Any gap differences of more than 3 mm were considered as a meaningful difference. Correlation between the difference with the demographic data, preoperative radiologic alignment and intraoperative data was analysed. For statistical analysis, ANOVA and Pearson’s correlation test were used. Results: The gaps in patella eversion demonstrated smaller gaps both in knee extension and flexion position compared to the gaps of patella reduction position. The amount of decreased gaps was more definite in knee flexion position. Statistically significant difference was observed for the lateral gap of patella eversion compared to gap of patella reduction in knee flexion position (p < 0.05). There were notable cases of variability in knee flexion position. Significant portion of 12 (24 %) knees of patella subluxation and 33 (66 %) knees of patella evertion demonstrated either increased or decreased gaps in knee flexion position compared to the gaps of patella reduction position. Conclusion: The gaps in patella eversion demonstrated smaller gaps both in knee extension and flexion position compared to the gaps of patella reduction position. The amount of decreased gaps was more definite in knee flexion position. Therefore, the intraoperative patellar positioning has influence on the measurement of the joint gap. Keeping the patella in reduced position is important during gap balancing. Level of evidence: I. © 2014, Springer-Verlag Berlin Heidelberg.


Hong D.Y.,Konkuk University | Park S.O.,Konkuk University | Lee K.R.,Konkuk University | Baek K.J.,Konkuk University | Shin D.H.,Sungkyunkwan University
Resuscitation | Year: 2012

Aim: To compare the time-dependent changes in the quality of chest compressions in 30:2 cardiopulmonary resuscitation (CPR) and hands-only cardiopulmonary resuscitation (HO-CPR) and to evaluate how individual rescuer factors affect the quality of chest compressions over time for both CPR techniques. Methods: Total 1028 adult hospital and university workers participated in CPR training programs including sessions of 30:2 CPR and HO-CPR. Tests of both CPR methods were performed in a random order using a manikin with Skill-Reporter™. Data were collected from 863 subjects. The time-dependent changes in chest compressions quality and the effects of individual rescuer factors (age, gender, body mass index (BMI), prior CPR training and experience) were analysed using the general linear model for a repeated-measures procedure. Results: In HO-CPR, the mean proportion of correct compressions depth (MPCD) decreased significantly throughout the time sectors following 20-40. s (74.4-50.4% in 100-120. s) compared to 30:2 CPR (83.4-76.3% in 100-120. s) (p< 0.0001). A significant decline of MPCD (MPCD < 70%) was initially observed at 40-60. s in HO-CPR, however, this pattern was not observed in 30:2 CPR. Individual rescuer factors minimally affected the time-dependent change in MPCD during 30:2 CPR. For HO-CPR, all rescuer factors except for male or obese/overweight (BMI ≥ 25) were associated with a significant declines of MPCD, and these decline were usually observed from 40 to 60. s. Conclusion: Switching rescuers at an interval of 2-min is reasonable for 30:2 CPR. However, for HO-CPR switching rescuers every 1-min may be preferable except when rescuers are male or obese/overweight (BMI ≥ 25). © 2011 Elsevier Ireland Ltd.


Lee J.-H.,Konkuk University | Na Y.,Konkuk University | Kim S.-K.,Konkuk University | Chung S.-K.,Sungkyunkwan University
Respiratory Physiology and Neurobiology | Year: 2010

Time-dependent characteristics of the flow in a human nasal airway constructed from the CT image of a healthy volunteer were investigated using a computational fluid dynamics (CFD) technique. To capture the time-varying nature of the flow as well as pressure and temperature fields, the large eddy simulation (LES) technique instead of the RANS (Reynolds Averaged Navier-Stokes) approach was adopted. To make the present analysis more relevant to a real human breathing cycle, the flow was designed to be induced by the pressure difference and the time-varying pressure at the end of trachea was described to reproduce the flow rate data from the measurement. Comparison of the present results with those of typical steady simulations showed that the difference in flow characteristics is magnified in the expiration phase. This fact may suggest that the inertial effect associated with unsteady flow is more important during the expiration period. Also, the fact that the distribution of the flow rate in a given cross-section of the airway changes significantly with time implies the importance of unsteady data for clinical decision. The wall shear stress was found to have relatively high values at the locations near nasopharynx and larynx but the magnitude changes with time during the whole respiratory cycle. Analysis of the temperature field showed that most of the temperature change occurs in the nasal cavity when the air is incoming and thus, the nasal cavity acts as a very efficient heat exchanger during an inspiration period. © 2010 Elsevier B.V.


Cheung K.,National Tsing Hua University | Cheung K.,Konkuk University | Yuan T.-C.,Academia Sinica, Taiwan
Physical Review Letters | Year: 2012

Current Higgs boson searches in various channels at the LHC point to an excess at around 124-126 GeV due to a possibly standard-model-like Higgs boson. If one examines more closely the channels (γγ, WW *, and ZZ *) that have excess, this "Higgs boson" may be the Randall-Sundrum radion ·. Because of the trace anomaly, the radion has stronger couplings to the photon and gluon pairs. Thus, it will enhance the production rates into gg and γγ, while those for WW *, ZZ *, and bb̄ are reduced relative to their standard model values. We show that it can match well with the data from CMS for m ·=124GeV, and the required scale Λ ·∼· is about 0.68 TeV. © 2012 American Physical Society.


Ha Y.,South Korean National Institute for Mathematical Sciences | Ho Kim C.,Konkuk University | Ju Lee Y.,Ewha Womans University | Yoon J.,Ewha Womans University
Journal of Computational Physics | Year: 2013

In this paper, we present a new smoothness indicator that evaluates the local smoothness of a function inside of a stencil. The corresponding weighted essentially non-oscillatory (WENO) finite difference scheme can provide the fifth convergence order in smooth regions, especially at critical points where the first derivative vanishes (but the second derivatives are non-zero). We provide a detailed analysis to verify the fifth-order accuracy. Some numerical experiments are presented to demonstrate the performance of the proposed scheme. We see that the proposed WENO scheme provides at least the same or improved behavior over the fifth-order WENO-JS scheme [10] and other fifth-order WENO schemes called as WENO-M [9] and WENO-Z [2], but its advantage seems more salient in two dimensional problems. © 2012 Elsevier Inc.


Lim H.,Ewha Womans University | Yim C.,Konkuk University | Swartzlander Jr. E.E.,University of Texas at Austin
IEEE Transactions on Computers | Year: 2010

High-speed IP address lookup is essential to achieve wire speed packet forwarding in Internet routers. The longest prefix matching for IP address lookup is more complex than exact matching because it involves dual dimensions: length and value. This paper presents a new formulation for IP address lookup problem using range representation of prefixes and proposes an efficient binary trie structure named a priority trie. In this range representation, prefixes are represented as ranges on a number line between 0 and 1 without expanding to the maximum length. The best match to a given input address is the smallest range that includes the input. The priority trie is based on the trie structure, with empty internal nodes in the trie replaced by the priority prefix which is the longest among those in the subtrie rooted by the empty nodes. The search ends when an input matches a priority prefix, which significantly improves the search performance. Performance evaluation using real routing data shows that the proposed priority trie is very good in performance metrics such as lookup speed, memory size, update performance, and scalability. © 2006 IEEE.


You J.S.,Konkuk University | Han J.H.,Sungkyunkwan University
Archives of Pharmacal Research | Year: 2014

The diverse epigenetic modifications regulate the gene expression and determine the cellular identity. Pioneering work over the past decades has highlighted that these epigenetic regulations establish normal development but also contribute various diseases. Furthermore, the epigenetic priming events are considered as a key factor for efficient master transcription factor(s) mediated reprogramming process. With the advent of numerous small molecules that target specific enzymes or proteins involved in the epigenetic regulation of gene expression, the utilization of epigenetic targets is emerging as a valuable approach to cancer therapy and cellular reprogramming. Here, we briefly present the basic principles of epigenetic regulations and review the recent application of epigenetic targeting small molecules. © 2014 The Pharmaceutical Society of Korea.


Jin X.,Korea University | Yin J.,Seoul National University | Kim S.-H.,Korea University | Sohn Y.-W.,Korea University | And 5 more authors.
Cancer Research | Year: 2011

Aberrant activation of receptor tyrosine kinases (RTK) is causally linked to the pathobiological traits of glioblastoma and genesis of glioma stem-like cells (GSC), but the underlying mechanism is still unknown. Here, we show that epidermal growth factor receptor (EGFR) signaling regulates the proliferation, angiogenesis, and acquisition of GSC characteristics by inducing inhibitor of differentiation 3 (ID3) and ID3-regulated cytokines [GRO1 and interleukins (IL)-6 and 8] induction. We found that EGFR-mediated ID3 expression was regulated by Smad5, which was directly phosphorylated by AKT. Furthermore, ID3 alone imparted GSC features to primary astrocytes derived from Ink4a/Arf-deficient mouse, and EGFR-ID3-IL-6 signaling axis gave rise to tumor cell heterogeneity. Conversely, EGFR inhibitors suppressed EGFR-AKT-Smad5-driven induction of ID3, which led to a decrease in the tumorsphere forming ability of GSCs and U87MG cells that possess an active mutant EGFR, EGFRvIII, without obvious cytotoxic effects. However, these cells seemed to regain colonogenic ability after removal of the EGFR inhibitors. Together, the results delineate a novel integrative molecular mechanism in which the RTK-ID signaling pathway governs genesis and maintenance of GBM histopathologic features, such as GSCs-based tumor initiation, progression, and angiogenesis. ©2011 AACR.


Lee Y.-S.,CHA Medical University | Kim T.-S.,CHA Medical University | Kim D.-K.,Konkuk University
BMC Cancer | Year: 2011

Background: Although the graft-versus-tumor (GVT) effect of donor-derived T cells after allogeneic hematopoietic stem cell transplantation has been used as an effective adoptive immunotherapy, the antitumor effects of cord blood (CB) transplantation have not been well studied.Methods: We established the animal model by transplantation of CB mononuclear cells and/or tumor cells into NOD/SCID mice. The presence of CB derived T cells in NOD/SCID mice or tumor tissues were determined by flow cytometric and immunohistochemical analysis. The anti-tumor effects of CB derived T cells against tumor was determined by tumor size and weight, and by the cytotoxicity assay and ELISPOT assay of T cells.Results: We found dramatic tumor remission following transfer of CB mononuclear cells into NOD/SCID mice with human cervical tumors with a high infiltration of CD3+T cells in tumors. NOD/SCID mice that receive neonatal CB transplants have reconstituted T cells with significant antitumor effects against human cervical and lung tumors, with a high infiltration of CD3+T cells showing dramatic induction of apoptotic cell death. We also confirmed that T cells showed tumor specific antigen cytotoxicity in vitro. In adoptive transfer of CD3+T cells into mice with pre-established tumors, we observed much higher antitumor effects of HPV-specific T cells by ELISPOT assays.Conclusions: Our results show that CB derived T lymphocytes will be useful for novel immunotherapeutic candidate cells for therapy of several tumors in clinic. © 2011 Lee et al; licensee BioMed Central Ltd.


Subramanian A.,Konkuk University | Wang H.-W.,Chung Yuan Christian University
Journal of Photochemistry and Photobiology A: Chemistry | Year: 2014

A hierarchal multilayer-structured photoelectrode was prepared and the performance of dye-sensitized solar cell was compared with the standard P25 electrodes in different thickness and bilayer-structured TiO2 electrode. Scanning electron microscope and X-ray diffraction patterns were used to analyze the morphology and crystal phases of these electrodes. The multilayer-structured photoelectrode showed a superior performance compared to those of the other three electrodes. The enhancement was attributed to higher amount of dye adsorption, large incident photon-to-current conversion yield due to greater fraction of light scattering and the good charge transportation because of the optimized structure of the TiO2 electrode. The UV-vis measurement confirmed the higher dye loading capacity of the multilayered-structure. Electrochemical spectra (EIS) were used to analyze the charge transport kinetic in these electrodes. The EIS analysis showed large electron injection rate, the suppression of recombination rate and longer electron lifetime in the multilayer-structured photoelectrode due to the optimized structure. The incident photon-to-current conversion efficiency measurement revealed the greater light harvesting efficiency of the multilayer-structured photo-electrode.


Kim Y.J.,Konkuk University | Lee M.W.,Sungkyunkwan University | Park H.S.,Konkuk University
Abdominal Imaging | Year: 2013

Current guidelines advocate percutaneous radiofrequency (RF) ablation as a standard treatment of early stage hepatocellular carcinoma (HCC) for up to three tumors ≤3 cm in diameter. The local efficacy evaluated with short-term radiological examination may be overrated, whereas that assessed by histopathological measure might be underestimated. Long-term clinical follow-up studies guarantee the effectiveness of RF ablation for small HCC, which is now almost comparable in benefits to surgical resection. US is the most common guiding modality for percutaneous RF ablation for small HCC. However, the technical feasibility is often limited due to poor conspicuity of the index tumor on US. Implementation of artificial ascites, contrast-enhanced harmonic US, and fusion imaging of US with CT/MR can be helpful to enhance the technical feasibility of US-guided RF ablation of small HCC. © 2012 Springer Science+Business Media, LLC.


Song J.-W.,Ewha Womans University | Jeon E.-Y.,Ewha Womans University | Song D.-H.,Ewha Womans University | Jang H.-Y.,Ewha Womans University | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2013

A multistep enzyme catalysis was successfully implemented to produce long-chain α,ω-dicarboxylic and ω-hydroxycarboxylic acids from renewable fatty acids and plant oils. Sebacic acid as well as ω-hydroxynonanoic acid and ω-hydroxytridec-11-enoic acid were produced from oleic and ricinoleic acid. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kim C.-H.,Konkuk University | Kim M.-B.,Sungkyunkwan University | Ban J.H.,Sungkyunkwan University
Laryngoscope | Year: 2014

Objectives/Hypothesis The aim of this study was to characterize the clinical features and typical positional nystagmus in patients with persistent geotropic direction-changing positional nystagmus (DCPN) and address the possible pathophysiology of the disease. Furthermore, the proportion of light cupula among the patients showing geotropic DCPN was investigated to assume the incidence of light cupula in those patients. Study Design Prospective case series. Methods We conducted a prospective case series study in 19 patients with persistent geotropic DCPN. Positional nystagmus during the bow and lean test and the supine head roll test was analyzed using videonystagmography. Results All of the 19 patients showed persistent geotropic DCPN without latency. A null plane in which the nystagmus ceases was identified in all of 19 patients, and the intensity of nystagmus was stronger on one side in13 patients (68%) on supine head roll test. Overall, the affected side could be identified in 18 patients (95%). About 14.2% (19 of 134) of patients with geotropic DCPN could be diagnosed as having light cupula in the horizontal semicircular canal. Conclusions The patients with light cupula show persistent geotropic DCPN without latency. Affected side(s) can be determined by the direction and intensity of the characteristic positional nystagmus and the side of the null plane. The pathophysiology and treatment of light cupula still remain to be elucidated. Level of Evidence 4. Laryngoscope, 124:E15-E19, 2014 © 2013 The American Laryngological, Rhinological and Otological Society, Inc.


Park H.W.,Konkuk University | Lee N.M.,Chung - Ang University | Kim J.H.,CHA Medical University | Kim K.S.,Konkuk University | Kim S.-N.,Konkuk University
Journal of Nutrition | Year: 2015

Background: Growing evidence indicates that fish oil-containing lipid emulsions have a beneficial effect on parenteral nutrition-associated cholestasis (PNAC) in adults; however, data are limited in neonates regarding the effect of fish oil on PNAC. Objective: We conducted a meta-analysis of studies that addressed the effect of fish oil-containing lipid emulsions on reversing and preventing PNAC. Methods: We searched PubMed, the EMBASE database, and the Cochrane Library for this systematic review and metaanalysis. The methodologic assessment of studies was performed with the Jadad scale and the Newcastle-Ottawa Scale. Comprehensive Met-Analysis version 2.0 was used for the statistical analysis. We performed a meta-analysis with the primary outcomes of reversal of PNAC and the occurrence of PNAC in newborn infants, including preterm infants, after parenteral administration of fish oil-containing lipid emulsions. Results: Of the 36 studies identified, 7 fulfilled the inclusion criteria and were used in this meta-analysis, including 3 studies with 93 participants in which reversal of PNAC was an outcome and 4 studies with 1012 participants on preventing PNAC. The use of fish oil-containing lipid emulsions was more likely to reverse PNAC (OR: 6.14; 95% CI: 2.27, 16.6; P < 0.01), but the use of fish oil-containing lipid emulsions did not have a significant effect on the development of PNAC (OR: 0.56; 95% CI: 0.28, 1.10; P = 0.09) compared with soybean-based or olive oil-based lipid emulsions. Conclusions: The pooled data suggest that the use of fish oil-containing lipid emulsions is effective for reversing PNAC but cannot prevent PNAC in neonates who require prolonged parenteral nutritional support. © 2015 American Society for Nutrition.


Yeo J.,Konkuk University | Moore M.A.,University of Manchester
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We study an M-p-spin spin glass model with p=3 and M=3 in three dimensions using the Migdal-Kadanoff renormalization group approximation (MKA). In this version of the p-spin model, there are three (M=3) Ising spins on each site. At mean-field level, this model is known to have two transitions; a dynamical transition and a thermodynamic one at a lower temperature. The dynamical transition is similar to the mode-coupling transition in glasses, while the thermodynamic transition possibly describes what happens at the Kauzmann temperature. We find that all the coupling constants in the model flow under the MKA to the high-temperature sink, implying that the mean-field features disappear in three dimensions and that there is no transition in this model. The behavior of the coupling constant flow is qualitatively similar to that of the model with p=3 and M=2, for which only a single transition is predicted at the mean-field level. We conclude that for p-spin models in three dimensions, fluctuation effects completely remove all traces of their mean-field behavior. © 2012 American Physical Society.


Kim S.-Y.,Hankyong National University | Lee J.-H.,Konkuk University | Park J.-H.,Catholic University of Korea
Theoretical Computer Science | Year: 2011

A k-disjoint path cover of a graph is defined as a set of k internally vertex-disjoint paths connecting given sources and sinks in such a way that every vertex of the graph is covered by a path in the set. In this paper, we analyze the k-disjoint path cover of recursive circulant G(2m,4) under the condition that at most f faulty vertices and/or edges are removed. It is shown that when m≥3, G(2m,4) has a k-disjoint path cover (of one-to-one type) joining any pair of two distinct source and sink for arbitrary f and k≥2 subject to f+k≤m. In addition, it is proven that when m≥5, G(2m,4) has a k-disjoint path cover (of unpaired many-to-many type) joining any two disjoint sets of k sources and k sinks for arbitrary f and k≥2 satisfying f+k≤m-1, in which sources and sinks are freely matched. In particular, the mentioned bounds f+k≤m and f+k≤m-1 of the two cases are shown to be optimal. © 2011 Elsevier B.V. All rights reserved.


Yeo J.,Konkuk University | Yeo J.,Korea Institute for Advanced Study | Moore M.A.,University of Manchester
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

Two versions of the M-p-spin glass model have been studied with the Migdal-Kadanoff renormalization group approximation. The model with p=3 and M=3 has at mean-field level the ideal glass transition at the Kauzmann temperature and at lower temperatures still the Gardner transition to a state like that of an Ising spin glass in a field. The model with p=3 and M=2 has only the Gardner transition. In the dimensions studied, d=2,3, and 4, both models behave almost identically, indicating that the growing correlation length as the temperature is reduced in these models-the analog of the point-to-set length scale-is not due to the mechanism postulated in the random first-order transition theory of glasses but is more like that expected on the analogy of glasses to the Ising spin glass in a field. © 2012 American Physical Society.


Kim J.,Sungkyunkwan University | Park J.-H.,Korea Atomic Energy Research Institute | Lee T.-H.,Konkuk University
Engineering Structures | Year: 2011

In this study, the sensitivity of design parameters of steel buildings subjected to progressive collapse is studied. To this end, design parameters such as yield strengths of beams, columns, and braces, live load, elastic modulus, and damping ratio were considered as random variables. The Monte Carlo simulation, the Tornado Diagram analysis, and the First-Order Second Moment method were applied to deal with the uncertainties involved in the design parameters. The analysis results showed that among the design variables beam yield strength was ultimately the most important design parameter in the moment-resisting frame buildings while the column yield strength was the most important design parameter in the dual system building. Sensitivity of the vertical displacement to uncertain member strength showed that progressive collapse mechanisms of the moment-resisting frame buildings and the dual system building completely differed due to different patterns of the vertical load redistribution. © 2010 Elsevier Ltd.


Kim Y.-H.,Ewha Womans University | Oh J.-H.,Konkuk University
Journal of Bone and Joint Surgery - Series B | Year: 2012

We compared the clinical and radiological outcomes of two cementless femoral stems in the treatment of patients with a Garden III or IV fracture of the femoral neck. A total of 70 patients (70 hips) in each group were enrolled into a prospective randomised study. One group received a short anatomical cementless stem and the other received a conventional cementless stem. Their mean age was 74.9 years (50 to 94) and 76.0 years (55 to 96), respectively (p = 0.328). The mean follow-up was 4.1 years (2 to 5) and 4.8 years (2 to 6), respectively. Perfusion lung scans and high resolution chest CTs were performed to detect pulmonary microemboli. At final follow-up there were no statistically significant differences between the short anatomical and the conventional stems with regard to the mean Harris hip score (85.7 (66 to 100) versus 86.5 (55 to 100); p = 0.791), the mean Western Ontario and McMaster Universities Osteoarthritis Index (17 (6 to 34) versus 16 (5 to 35); p = 0.13) or the mean University of California, Los Angeles activity score (5 (3 to 6) versus 4 (3 to 6); p = 0.032). No patient with a short stem had thigh pain, but 11 patients (16%) with a conventional stem had thigh pain. No patients with a short stem had symptomatic pulmonary microemboli, but 11 patients with a conventional stem had pulmonary microemboli (symptomatic in three patients and asymptomatic in eight patients). One hip (1.4%) in the short stem group and eight (11.4%) in the conventional group had an intra-operative undisplaced fracture of the calcar. No component was revised for aseptic loosening in either group. One acetabular component in the short stem group and two acetabular components in the conventional stem group were revised for recurrent dislocation. Our study demonstrated that despite the poor bone quality in these elderly patients with a fracture of the femoral neck, osseo-integration was obtained in all hips in both groups. However, the incidence of thigh pain, pulmonary microemboli and peri-prosthetic fracture was significantly higher in the conventional stem group than in the short stem group. ©2012 British Editorial Society of Bone and Joint Surgery.


Na Y.,Konkuk University | Chung K.S.,Konkuk University | Chung S.-K.,Sungkyunkwan University | Kim S.K.,Konkuk University
Respiratory Physiology and Neurobiology | Year: 2012

Knowledge of airflow characteristics in the nasal cavity is essential to understanding the physiologic and pathologic aspects of nasal breathing. Airflows inside post-surgery models were investigated both experimentally and numerically to simulate the inferior turbinectomy. The left cavities of all three models are normal and right cavity is modified by (1) excision of the head of the inferior turbinate, (2) resection of the lower fifth of the inferior turbinate, and (3) resection of almost the entire inferior turbinate. Thin-slice CT (computed tomography) data (0.6. mm deep) and meticulous refinement of the model surface by over a decade-long collaboration between engineers and an experienced ENT doctor resulted in the creation of sophisticated nasal cavity models. After numerical experiments and validation by comparison with the PIV results, the CFD code using the Reynolds stress turbulent model and variable temperature boundary condition on the mucosal wall was chosen as the proper numerical framework. Both global quantities (pressure drop, flow rate ratio, total wall heat transfer) and local changes (velocity, temperature, humidity, pressure gradient, and wall shear stress) were numerically investigated. The turbinectomy obviously altered the main stream direction. The flow rate in the upper airway near the olfactory slit decreased in models (1) and (3). This may weaken the olfactory function of the nose. Fluid and thermal properties that are believed to be related with physiology and prognosis are dependent on turbinate resection volume, position, and manner. Widening of the inferior airway does not always result in decreased flow resistance or wall heat transfer. The gains and losses of inferior turbinectomy were considered by analysis of the post-surgery model results. Nasal resistance was increased in model (1) due to sudden airway expansion. Nasal resistance increased and the wall heat transfer decreased in model (3) due to sudden airway expansion and excessive reduction of the mucosal wall surface area. Local shear stress and pressure gradient levels were increased in models (1) and (3). © 2011 Elsevier B.V.


Kim D.S.H.L.,CORE , Inc. | Kim J.Y.,Ministry of Health and Welfare | Han Y.,Konkuk University
Recent Patents on CNS Drug Discovery | Year: 2012

Neurodegeneration is a term used to describe progressive deterioration of structure and/or function of neurons that affects different parts of the central nervous system and leads to eventual death. Neurodegenerative diseases include Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and Down's syndrome (DS), multiple sclerosis (MS), glaucoma, age-related macular degeneration (AMD), and diabetic encephalopathy (DE). Although the initial events that trigger these disorders may be different from each other, they share similar biochemical reactions that lead to neurodegeneration. Curcuminoids, polyphenol compounds from turmeric (Curcuma longa), possess diverse biological properties that modulate debilitating biochemical processes involved in AD that include attenuation of mitochondrial dysfunction-induced oxidative stress and inflammatory responses to inflammatory cytokines, COX-2, and iNOS. Curcuminoids also bind to β-amyloid (Aβ) plaques to inhibit amyloid accumulation and aggregation in the brain, in addition to inhibiting the toxic Aβ oligomer formation and oligomer-dependent Aβ toxicity. These properties can be further elaborated to DS, glaucoma and AMD. Curcuminoids also prevent α-synuclein aggregation in PD; attenuate ROS-induced COX-2 expression in ALS; ameliorate the symptoms of MS, DE and traumatic brain injury, in addition to neurodamages caused by heavy metal poisoning. These results demonstrate curcuminoids may be potentially effective therapeutic means to treat neurodegenerative diseases. A bulk of patents discloses methods to improve bioavailability of curcuminoids for therapeutic development. This review provides a comprehensive description on the current progress on curcuminoids against neurodegenerative diseases. © 2012 Bentham Science Publishers.


Yadav S.K.,Konkuk University | Mahapatra S.S.,Konkuk University | Cho J.W.,Konkuk University | Lee J.Y.,Agency for Defense Development
Journal of Physical Chemistry C | Year: 2010

Multiwalled carbon nanotubes (MWCNTs) were functionalized with poly(styrene-b-(ethylene-co-butylene)-b-styrene) triblock copolymer (SEBS) using click chemistry. Different compositions of SEBS-functionalized MWCNTs were obtained from reaction of azide moiety-containing SEBS on styrene units with alkyne-decorated MWCNTs. The SEBS-functionalized MWCNTs were characterized by FT-IR, Raman, XPS, SEM, and TEM measurements. The functionalized MWCNTs showed excellent dispersion in the SEBS matrix, and as a result, remarkably increased mechanical properties and high dielectric constants as well as enhanced thermal stability were obtained. The click coupled bonding of MWCNT with SEBS was very effective for controlling the material properties and achieving high performance materials. © 2010 American Chemical Society.


Lee S.K.,Sungkyunkwan University | Yang J.-H.,Konkuk University | Woo S.-Y.,Samsung | Lee J.E.,Sungkyunkwan University | Nam S.J.,Sungkyunkwan University
British Journal of Surgery | Year: 2013

Background The aim of this study was to identify risk factors for invasive breast cancer in patients diagnosed with ductal carcinoma in situ (DCIS) on a preoperative biopsy. These factors were used to develop a nomogram for predicting the risk of invasion in the preoperative setting. Methods This was a retrospective analysis of patients who underwent surgical treatment for DCIS diagnosed before surgery between 1997 and 2009. Multivariable analysis was used to identify clinical, radiological and histopathological factors that may predict upstaging. A nomogram was developed to predict the probability of invasion using multiple logistic regression analysis. This nomogram was subsequently validated using another cohort of patients with a preoperative diagnosis of DCIS between 2010 and 2012. Results Upstaging to invasive cancer occurred in 123 (24.9 per cent) of 493 women treated between 1997 and 2009. A larger DCIS lesion (at least 15 mm), lack of hormone receptor expression, intermediate or high nuclear grade, diagnosis on core biopsy compared with vacuum-assisted biopsy, and non-cribriform subtype of DCIS were significantly associated with upstaging. A nomogram developed using these factors demonstrated good predictive performance (area under the receiver operating characteristic (ROC) curve (AUC) 0·823, 95 per cent confidence interval 0·787 to 0·860). The nomogram showed similar predictive performance in the validation data set, based on another 149 women (AUC 0·700, 0·613 to 0·786). Conclusion Upstaging to invasive cancer in women with a preoperative diagnosis of DCIS is common. A nomogram based on the five most significant factors related to upstaging accurately predicted invasive cancer. This nomogram may be useful when deciding whether to pursue axillary staging with sentinel lymph node biopsy in patients with DCIS. A tool for making a wise decision on sentinel node biopsy © 2013 British Journal of Surgery Society Ltd. Published by John Wiley & Sons Ltd.


Nam J.,Konkuk University | Paik J.,Sungkyunkwan University | Won D.,Sungkyunkwan University
Information Sciences | Year: 2011

In TCC '07, Abdalla et al. presented a protocol compiler that transforms any authenticated 2-party key exchange protocol into an authenticated group key exchange (GKE) protocol. Abdalla et al.'s compiler is certainly elegant in its genericness, symmetry, simplicity and efficiency. However, this compiler is not as secure as claimed. Under a reasonable assumption, the GKE protocol constructed by the compiler (from a 2-party protocol) fails to achieve implicit key authentication. We here reveal this security problem with the compiler and show how to address it. © 2010 Elsevier Inc. All rights reserved.


Lim Y.-S.,University of Ulsan | Byun K.S.,Korea University | Yoo B.C.,Sungkyunkwan University | Kwon S.Y.,Konkuk University | And 4 more authors.
Gut | Year: 2016

Objective: Little clinical data are available regarding the optimal treatment of patients who harbour entecavir (ETV)-resistant HBV. Design: In this multicentre randomised trial, patients who had HBV with ETV resistance-associated mutations and serum HBV DNA concentrations >60 IU/mL were randomised to receive tenofovir disoproxil fumarate (TDF, 300 mg/day) monotherapy (n=45) or TDF and ETV (1 mg/day) combination therapy (n=45) for 48 weeks. Results: Baseline characteristics were comparable between groups, including HBV DNA levels (median, 4.02 log10 IU/mL) and hepatitis B e antigen-positivity (89%). All patients had at least one ETV-resistance mutation: rtT184A/C/F/G/I/L/S (n=49), rtS202G (n=43) and rtM250L/V (n=7), in addition to rtM204V/I (n=90). All except one patient in the TDF group completed 48 weeks of treatment. At week 48, the proportion of patients with HBV DNA <15 IU/mL, the primary efficacy endpoint, was not significantly different between the TDF and TDF+ETV groups (71% vs 73%; p>0.99). The mean change in HBV DNA levels from baseline was not significantly different between groups (-3.66 vs-3.74 log10 IU/mL; p=0.81). Virological breakthrough occurred in one patient on TDF, which was attributed to poor drug adherence. At week 48, six and three patients in the TDF and TDF+ETV groups, respectively, retained their baseline resistance mutations (p>0.99). None developed additional resistance mutations. Safety profiles were comparable in the two groups. Conclusions: TDF monotherapy for 48 weeks provided a virological response comparable to that of TDF and ETV combination therapy in patients infected with ETV-resistant HBV. Trial registration number ClinicalTrials.gov ID NCT01639092.


Han D.W.,Max Planck Institute for Molecular Biomedicine | Tapia N.,Max Planck Institute for Molecular Biomedicine | Joo J.Y.,Max Planck Institute for Molecular Biomedicine | Greber B.,Max Planck Institute for Molecular Biomedicine | And 8 more authors.
Cell | Year: 2010

Embryonic stem cells (ESCs) comprise at least two populations of cells with divergent states of pluripotency. Here, we show that epiblast stem cells (EpiSCs) also comprise two distinct cell populations that can be distinguished by the expression of a specific Oct4-GFP marker. These two subpopulations, Oct4-GFP positive and negative EpiSCs, are capable of converting into each other in vitro. Oct4-GFP positive and negative EpiSCs are distinct from ESCs with respect to global gene expression pattern, epigenetic profile, and Oct4 enhancer utilization. Oct4-GFP negative cells share features with cells of the late mouse epiblast and cannot form chimeras. However, Oct4-GFP positive EpiSCs, which only represent a minor EpiSC fraction, resemble cells of the early epiblast and can readily contribute to chimeras. Our findings suggest that the rare ability of EpiSCs to contribute to chimeras is due to the presence of the minor EpiSC fraction representing the early epiblast. © 2010 Elsevier Inc.


Choo K.-K.R.,University of South Australia | Nam J.,Konkuk University | Won D.,Sungkyunkwan University
Information Sciences | Year: 2014

We describe a mechanical approach to derive identity-based (ID-based) protocols from existing Diffie-Hellman-based ones. As case studies, we present the ID-based versions of the Unified Model protocol, UMP-ID, Blake-Wilson et al. (1997)'s protocol, BJM-ID, and Krawczyk (2005)'s HMQV protocol, HMQV-ID. We describe the calculations required to be modified in existing proofs. We conclude with a comparative security and efficiency of the three proposed ID-based protocols (relative to other similar published protocols) and demonstrate that our proposed ID-based protocols are computationally efficient. © 2014 Elsevier Inc. All rights reserved.


Kim Y.G.,Gwangju National University of Education | Lee K.Y.,Konkuk University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We study the phenomenology of the heavy charged gauge boson and obtain the lower bounds on its mass with the early LHC data at 7 TeV center-of-mass energy in the nonuniversal gauge interaction model, in which the electroweak SU(2) gauge group depends upon the fermion family. We found that the direct bound with the early data of the LHC is already better than the indirect bound on the mass of the W' boson. © 2011 Elsevier B.V.


Cheung K.,Konkuk University | Cheung K.,National Tsing Hua University | Cheung K.,National Center for Theoretical science | Yuan T.-C.,Academia Sinica, Taiwan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

The forward-backward asymmetry in top-pair production that was observed in 2008 gets a boost in a recent CDF publication. Not only has the forward-backward asymmetry been further confirmed, but also distributional preferences are shown. Strikingly, the forward-backward asymmetry is the most sizable in the large Mtt̄ invariant mass region and in the large rapidity difference |Δy| region. Here we used our previously proposed t-channel exchanged W′ boson to explain the new observations. We show that a new particle exchanged in the t channel generically gives rise to such observations. Furthermore, we show that the proposed W′ can be directly produced in association with a top quark at the Tevatron and the LHC. We perform a signal-background analysis and show that such a W′ is readily observed at the Tevatron with a 10fb-1 luminosity and at the LHC-7 with just a 100pb-1 luminosity. © 2011 American Physical Society.


Shin D.-H.,Sungkyunkwan University | Hwang Y.,Konkuk University | Choo H.,Sungkyunkwan University
Behaviour and Information Technology | Year: 2013

Smart TV (STV), a new digital television service, has been rapidly developing, particularly in Korea. With the conceptual model of interactivity, this study empirically investigates the effects of perceived interactivity on the motivations and attitudes towards STV in Korea. The model is created to validate the relationship of perceived interactivity to performance, attitude and intention. Further, the model examines the mediating roles of perceived interactivity in the effect of performance on attitude towards STV. Empirical evidence supports the mediating role of perceived interactivity. Implications of the findings are discussed in terms of building a theory of interactivity and providing practical insights into developing a user-centred STV interface. © 2013 Copyright Taylor and Francis Group, LLC.


Cheung K.,Konkuk University | Cheung K.,National Tsing Hua University | Keung W.-Y.,University of Illinois at Chicago | Yuan T.-C.,Academia Sinica, Taiwan
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Recently Weinberg suggested that Goldstone bosons arising from the spontaneous breakdown of some global hidden symmetries can interact weakly in the early Universe and account for a fraction of the effective number of neutrino species Neff, which has been reported persistently 1σ away from its expected value of three. In this work, we study in some details a number of experimental constraints on this interesting idea based on the simplest possibility of a global U(1), as studied by Weinberg. We work out the decay branching ratios of the associated light scalar field σ and suggest a possible collider signature at the Large Hadron Collider. In some corners of the parameter space, the scalar field σ can decay into a pair of pions with a branching ratio of order O(1)% while the rest is mostly a pair of Goldstone bosons. The collider signature would be gluon fusion into the standard model Higgs boson gg→H or associated production with a W gauge boson qq̄′→HW, followed by H→σσ→(ππ) (αα) where α is the Goldstone boson. © 2014 American Physical Society.


Cheung K.,Konkuk University | Cheung K.,National Tsing Hua University | Cheung K.,National Center for Theoretical science | Yuan T.-C.,Academia Sinica, Taiwan
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

With the assumption that the dominant diagram in supersymmetry for the spin-independent cross section of the dark matter particle is due to Higgs boson exchange, we obtain an upper limit on the Higgs-dark-matter coupling based on the new result of the CDMSII Collaborations. Based on the assumption that the Higgs boson can kinematically decay into a pair of the dark matter particles as it is likely that the dark matter particle is rather light from the measured recoil energies, we obtain an upper limit on the invisible width of the Higgs boson. Numerically it is less than 20-120 MeV for mh ≃ 120 - 180 GeV. Implications for Higgs boson search are also discussed. © 2010 Elsevier B.V. All rights reserved.


Novick D.,Weizmann Institute of Science | Kim S.,Konkuk University | Kaplanski G.,Aix - Marseille University | Dinarello C.A.,University of Colorado at Denver | Dinarello C.A.,University Medical Center Nijmegen
Seminars in Immunology | Year: 2013

Together with IL-12 or IL-15, interleukin-18 (IL-18) plays a major role in the production of interferon-γ from T-cells and natural killer cells; thus, IL-18 is considered to have a major role in the Th1 response. However, without IL-12, IL-18 is proinflammatory in an IFNγ independent manner. IL-18 is a member of the IL-1 family of cytokines and similar to IL-1β, the cytokine is synthesized as an inactive precursor requiring processing by caspase-1 into an active cytokine. IL-18 is also present as an integral membrane protein but requires caspase-1 for full activity in order to induce IFNγ. Uniquely, unlike IL-1β, the IL-18 precursor is constitutively present in nearly all cells in healthy humans and animals. The activity of IL-18 is balanced by the presence of a high-affinity, naturally occurring IL-18 binding protein (IL-18BP). In humans, increased disease severity can be associated with an imbalance of IL-18 to IL-18BP such that the levels of free IL-18 are elevated in the circulation. Increasing number of studies have expanded the role of IL-18 in mediating inflammation in animal models of disease using the IL-18BP, IL-18 deficient mice, neutralization of IL-18 or deficiency in the IL-18 receptor alpha chain. A role for IL-18 has been implicated in several autoimmune diseases, myocardial function, emphysema, metabolic syndromes, psoriasis, inflammatory bowel disease, macrophage activation syndrome, sepsis and acute kidney injury, although paradoxically, in some models of disease, IL-18 is protective. The IL-18BP has been used safely in humans and clinical trials of IL-18BP as well as neutralizing anti-IL-18 antibodies are being tested in various diseases. © 2013 Elsevier Ltd.


Dinarello C.A.,University of Colorado at Denver | Dinarello C.A.,University Medical Center Nijmegen | Novick D.,Weizmann Institute of Science | Kim S.,Konkuk University | Kaplanski G.,Aix - Marseille University
Frontiers in Immunology | Year: 2013

Interleukin-18 (IL-18) is a member of the IL-1 family of cytokines. Similar to IL-1ß, IL-18 is synthesized as an inactive precursor requiring processing by caspase-1 into an active cytokine but unlike IL-1ß, the IL-18 precursor is constitutively present in nearly all cells in healthy humans and animals. The activity of IL-18 is balanced by the presence of a high affinity, naturally occurring IL-18 binding protein (IL-18BP). In humans, increased disease severity can be associated with an imbalance of IL-18 to IL-18BP such that the levels of free IL-18 are elevated in the circulation. Increasing number of studies have expanded the role of IL-18 in mediating inflammation in animal models of disease using the IL-18BP, IL-18-deficient mice, neutralization of IL-18, or deficiency in the IL-18 receptor alpha chain. A role for IL-18 has been implicated in several autoimmune diseases, myocardial function, emphysema, metabolic syndromes, psoriasis, inflammatory bowel disease, hemophagocytic syndromes, macrophage activation syndrome, sepsis, and acute kidney injury, although in some models of disease, IL-18 is protective. IL-18 plays a major role in the production of interferon-γ from T-cells and natural killer cells. The IL-18BP has been used safely in humans and clinical trials of IL-18BP as well as neutralizing anti-IL-18 antibodies are in clinical trials. This review updates the biology of IL-18 as well as its role in human disease. © 2013 Dinarello, Novick, Kim and Kaplanski.


Chun J.-Y.,Konkuk University | Choi M.-J.,Konkuk University | Min S.-G.,Konkuk University | Weiss J.,University of Hohenheim
Food Hydrocolloids | Year: 2013

The sequential deposition of biopolymers onto the surface of liposomes; lamellar bilayer vesicles composed of polar lipids; was investigated. Submicron-sized liposomes were prepared from lecithin with a high speed blender and an ultrasonic homogenizer. Positively (chitosan), and negatively (high methoxyl pectin and λ-carrageenan) charged biopolymers were alternatingly added to liposomes to build up to 6 sequentially-stacked interfacial layers on top of the phospholipid membranes. After formulation, particle size and ζ-potential of liposomes were determined using dynamic light scattering. The primary liposomes had diameters of approximately 80 nm. Particle size increased linearly with each successive deposition up to four layers but increased to several micrometers when a fifth and sixth layer was deposited indicating that aggregation may have occurred. Addition of λ-carrageenan as an anionic biopolymer led to less aggregation than when high methoxyl pectin was used. Results were attributed to (i) unbound polymers in the aqueous phase forming coacervates that may lead to depletion flocculation and (ii) unoccupied binding sites and uneven charge distributions causing bridging flocculation. Our results show the limitations of the layer-by-layer deposition approach, which is important for food manufacturers wishing to form very thick polymer layers to stabilize dispersions such as emulsions or liposomes. © 2012 Elsevier Ltd.


Lee P.,Korea Advanced Institute of Science and Technology | Lee J.,Korea Advanced Institute of Science and Technology | Lee H.,Korea Electronics Technology Institute | Yeo J.,Korea Advanced Institute of Science and Technology | And 5 more authors.
Advanced Materials | Year: 2012

A highly stretchable metal electrode is developed via the solution-processing of very long (>100 μm) metallic nanowires and subsequent percolation network formation via low-temperature nanowelding. The stretchable metal electrode from very long metal nanowires demonstrated high electrical conductivity (9 ohm sq -1) and mechanical compliance (strain > 460%) at the same time. This method is expected to overcome the performance limitation of the current stretchable electronics such as graphene, carbon nanotubes, and buckled nanoribbons. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Patent
Konkuk University, KR Biotech Co., Lee, Park and Kim | Date: 2010-10-20

The present invention relates to a recombinant baculovirus comprising: (a) a nucleotide sequence encoding a foreign virus envelope protein; (b) a first promoter operatively linked to the envelope-encoding nucleotide sequence; (c) a nucleotide sequence encoding an antigen protein; and (d) a second promoter operatively linked to the antigen-encoding nucleotide sequence; and a vaccine composition using the same. The recombinant baculovirus of the present invention has an excellent efficacy on both humoral and cellular immune responses against a specific antigen (e.g., HPV L1), enabling to function as a more efficient DNA vaccine.


Kim S.K.,Konkuk University | Na Y.,Konkuk University | Kim J.-I.,Konkuk University | Chung S.-K.,Sungkyunkwan University
Journal of Biomechanics | Year: 2013

Respiratory physiology and pathology are strongly dependent on the airflow inside the nasal cavity. However, the nasal anatomy, which is characterized by complex airway channels and significant individual differences, is difficult to analyze. Thus, commonly adopted diagnostic tools have yielded limited success. Nevertheless, with the rapid advances in computer resources, there have been more elaborate attempts to correlate airflow characteristics in human nasal airways with the symptoms and functions of the nose by computational fluid dynamics study. Furthermore, the computed nasal geometry can be virtually modified to reflect predicted results of the proposed surgical technique. In this article, several computational fluid mechanics (CFD) issues on patient-specific three dimensional (3D) modeling of nasal cavity and clinical applications were reviewed in relation to the cases of deviated nasal septum (decision for surgery), turbinectomy, and maxillary sinus ventilation (simulated- and post-surgery). Clinical relevance of fluid mechanical parameters, such as nasal resistance, flow allocation, wall shear stress, heat/humidity/NO gas distributions, to the symptoms and surgical outcome were discussed. Absolute values of such parameters reported by many research groups were different each other due to individual difference of nasal anatomy, the methodology for 3D modeling and numerical grid, laminar/turbulent flow model in CFD code. But, the correlation of these parameters to symptoms and surgery outcome seems to be obvious in each research group with subject-specific models and its variations (virtual- and post-surgery models). For the more reliable, patient-specific, and objective tools for diagnosis and outcomes of nasal surgery by using CFD, the future challenges will be the standardizations on the methodology for creating 3D airway models and the CFD procedures. © 2012 Elsevier Ltd.


Patent
Konkuk University and KR Biotech Co. | Date: 2014-07-30

The present invention relates to a recombinant baculovirus comprising: (a) a nucleotide sequence encoding a foreign virus envelope protein; (b) a first promoter operatively linked to the envelope-encoding nucleotide sequence; (c) a nucleotide sequence encoding an antigen protein; and (d) a second promoter operatively linked to the antigen-encoding nucleotide sequence; and a vaccine composition using the same. The recombinant baculovirus of the present invention has an excellent efficacy on both humoral and cellular immune responses against a specific antigen (e.g., HPV L1), enabling to function as a more efficient DNA vaccine.


Sprague I.B.,Washington State University | Dutta P.,Washington State University | Dutta P.,Konkuk University
Numerical Heat Transfer; Part A: Applications | Year: 2011

A mathematical model for laminar flow fuel cells including electrical double layer and ion transport effects is developed. The model consists of the Poisson-Nernst-Plank equations and the modified Navier-Stokes equations to account for the advection of species in the downstream direction. The generalized Frumkin-Butler-Volmer equation is used for the fuel cell kinetics. The finite-volume method is used to develop a system of algebraic equations from the governing partial differential equations, and a numerical algorithm is developed to obtain the results. The accuracy of the 2-D numerical simulation is validated against published results using a 1-D analytical solution. Numerical results show that the concentration distributions for both the neutral species and ions change in both the cross-stream and streamwise directions. An especially interesting result is the change in positive ion concentration within the electrical double layer along the streamwise direction. A study on the importance of the electric body force in the momentum conservation equations is also presented. It is found that the flow results are only affected by the electric body force term at the start of the electrodes and has a negligible impact on device performance results. This model allows us to study both kinetically active (electrodes) and inactive (insulated wall) regions for a microfluidic fuel cell. The mathematical model and numerical simulation will be particularly useful in analyzing the complex behavior that occurs in laminar flow electrochemical devices where a minimum of two spatial dimensions must be considered and the electrical double layer and ion transport cannot be neglected. Copyright © 2011 Taylor & Francis Group, LLC.


Lee W.H.,Konkuk University | Park Y.D.,Incheon National University
Polymers | Year: 2014

We reviewed recent advances in high-performance organic field-effect transistors (OFETs) based on organic semiconductor/insulator polymer blends. Fundamental aspects of phase separation in binary blends are discussed with special attention to phase-separated microstructures. Strategies for constructing semiconductor, semiconductor/dielectric, or semiconductor/passivation layers in OFETs by blending organic semiconductors with an insulating polymer are discussed. Representative studies that utilized such blended films in the following categories are covered: vertical phase-separation, processing additives, embedded semiconductor nanowires. © 2014 by the authors.


Kim J.,Seoul National University | Kim J.,Konkuk University | Lee H.J.,Seoul National University | Lee K.W.,Konkuk University
Journal of Neurochemistry | Year: 2010

Alzheimer's disease (AD) is an age-related neurodegenerative disease increasingly recognized as one of the most important medical problems affecting the elderly. Although a number of drugs, including several cholinesterase inhibitors and an NMDA receptor antagonist, have been approved for use, they have been shown to produce diverse side effects and yield relatively modest benefits. To overcome these limitations of current therapeutics for AD, extensive research and development are underway to identify drugs that are effective and free of undesirable side effects. Certain naturally occurring dietary polyphenolic phytochemicals have received considerable recent attention as alternative candidates for AD therapy. In particular, curcumin, resveratrol, and green tea catechins have been suggested to have the potential to prevent AD because of their anti-amyloidogenic, anti-oxidative, and anti-inflammatory properties. These polyphenolic phytochemicals also activate adaptive cellular stress responses, called 'neurohormesis', and suppress disease processes. In this commentary, we describe the amyloid-β-induced pathogenesis of AD, and summarize the intracellular and molecular targets of selected dietary phytochemicals that might slow the progression of AD. © 2010 International Society for Neurochemistry.


Cho Y.M.,Konkuk University | Cho Y.M.,Seoul National University
International Journal of Modern Physics A | Year: 2014

We demonstrate the monopole condensation in SU(3) QCD. We first discuss the gauge independent and Weyl symmetric Abelian (Cho-Duan-Ge) decomposition of the SU(3) QCD, and present a new gauge invariant integral expression of the one-loop effective action which has no infrared divergence. Integrating it gauge invariantly imposing the color reflection invariance ("the C-projection") we show that the effective potential generates the stable monopole condensation which generates the mass gap. © 2014 World Scientific Publishing Company.


Cundy N.,Seoul National University | Cho Y.M.,Konkuk University | Cho Y.M.,Seoul National University | Lee W.,Seoul National University | Leem J.,Seoul National University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014

We investigate the relationship between colour confinement and topological structures derived from the gauge invariant Abelian (Cho-Duan-Ge) decomposition. This Abelian decomposition is made imposing an isometry on a colour field n which selects the Abelian direction; the principle novelty of our study is that we have defined this field in terms of the eigenvectors of the Wilson loop. This allows us to establish an equivalence between the path ordered integral of the non-Abelian gauge fields with an integral over an Abelian restricted gauge field which is tractable both theoretically and numerically in lattice QCD. By using Stokes' theorem, we can relate the Wilson loop in terms of a surface integral over a restricted field strength, and show that the restricted field strength may be dominated by topological structures, which occur when one of the parameters parametrising the colour field n winds itself around a non-analyticity in the colour field. If they exist, these objects will lead to an area law scaling for the Wilson loop and provide a mechanism for quark confinement. We search for these structures in quenched lattice QCD. We perform the Abelian decomposition, and find that the restricted field strength is dominated by peaks on the lattice. Wilson loops containing these peaks show a stronger area-Law and thus provide the dominant contribution to the string tension. © 2014 The Authors.


Lim J.-H.,Dana-Farber Cancer Institute | Lim J.-H.,Harvard University | Lim J.-H.,Konkuk University | Luo C.,Dana-Farber Cancer Institute | And 5 more authors.
Cancer Research | Year: 2014

Metabolic targets offer attractive opportunities for cancer therapy. However, their targeting may activate alternative metabolic pathways that can still support tumor growth. A subset of human melanomas relies on PGC1a-dependent mitochondrial oxidative metabolism to maintain growth and survival. Herein, we showthat loss of viability caused by suppression of PGC1a in these melanomas is rescued by induction of glycolysis. Suppression of PGC1a elevates reactive oxygen species levels decreasing hypoxia-inducible factor-1a (HIF1a) hydroxylation that, in turn, increases its protein stability. HIF1a reprograms melanomas to become highly glycolytic and dependent on this pathway for survival. Dual suppression of PGC1a and HIF1a causes energetic deficits and loss of viability that are partially compensated by glutamine utilization. Notably, triple suppression of PGC1a, HIF1a, and glutamine utilization results in complete blockage of tumor growth. These results show that due to high metabolic and bioenergetic flexibility, complete treatment of melanomas will require combinatorial therapy that targets multiple metabolic components. © 2014 AACR.


Kim H.,Seoul National University | Lee S.-A.,Seoul National University | Kim D.-W.,Seoul National University | Lee S.-H.,Konkuk University | Kim B.-J.,Seoul National University
PLoS ONE | Year: 2013

Molecular mechanisms related to occult hepatitis B virus (HBV) infection, particularly those based on genotype C infection, have rarely been determined thus far in the ongoing efforts to determine infection mechanisms. Therefore, we aim to elucidate the mutation patterns in the surface open reading frame (S ORF) underlying occult infections of HBV genotype C in the present study. Nested PCRs were applied to 624 HBV surface antigen (HBsAg) negative Korean subjects. Cloning and sequencing of the S ORF gene was applied to 41 occult cases and 40 control chronic carriers. Forty-one (6.6%) of the 624 Korean adults with HBsAg-negative serostatus were found to be positive for DNA according to nested PCR tests. Mutation frequencies in the three regions labeled here as preS1, preS2, and S were significantly higher in the occult subjects compared to the carriers in all cases. A total of two types of deletions, preS1 deletions in the start codon and preS2 deletions as well as nine types of point mutations were significantly implicated in the occult infection cases. Mutations within the "a" determinant region in HBsAg were found more frequently in the occult subjects than in the carriers. Mutations leading to premature termination of S ORF were found in 16 occult subjects (39.0%) but only in one subject from among the carriers (2.5%). In conclusion, our data suggest that preS deletions, the premature termination of S ORF, and "a" determinant mutations are associated with occult infections of HBV genotype C among a HBsAg-negative population. The novel mutation patterns related to occult infection introduced in the present study can help to broaden our understanding of HBV occult infections. © 2013 Kim et al.


Gurunathan S.,Konkuk University | Gurunathan S.,GS Institute of Bio and Nanotechnology | Han J.W.,Konkuk University | Kwon D.-N.,Konkuk University | Kim J.-H.,Konkuk University
Nanoscale Research Letters | Year: 2014

Silver nanoparticles (AgNPs) have been used as antibacterial, antifungal, antiviral, anti-inflammtory, and antiangiogenic due to its unique properties such as physical, chemical, and biological properties. The present study was aimed to investigate antibacterial and anti-biofilm activities of silver nanoparticles alone and in combination with conventional antibiotics against various human pathogenic bacteria. Here, we show that a simple, reliable, cost effective and green method for the synthesis of AgNPs by treating silver ions with leaf extract of Allophylus cobbe. The A. cobbe-mediated synthesis of AgNPs (AgNPs) was characterized by ultraviolet-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the antibacterial and anti-biofilm activity of antibiotics or AgNPs, or combinations of AgNPs with an antibiotic was evaluated using a series of assays: such as in vitro killing assay, disc diffusion assay, biofilm inhibition, and reactive oxygen species generation in Pseudomonas aeruginosa, Shigella flexneri, Staphylococcus aureus, and Streptococcus pneumonia. The results suggest that, in combination with antibiotics, there were significant antimicrobial and anti-biofilm effects at lowest concentration of AgNPs using a novel plant extract of A. cobbe, otherwise sublethal concentrations of the antibiotics. The significant enhancing effects were observed for ampicillin and vancomycin against Gram-negative and Gram-positive bacteria, respectively. These data suggest that combining antibiotics and biogenic AgNPs can be used therapeutically for the treatment of infectious diseases caused by bacteria. This study presented evidence of antibacterial and anti-biofilm effects of A. cobbe-mediated synthesis of AgNPs and their enhanced capacity against various human pathogenic bacteria. These results suggest that AgNPs could be used as an adjuvant for the treatment of infectious diseases. © 2014 Gurunathan et al.; licensee Springer.


Cho Y.M.,Konkuk University | Cho Y.M.,Seoul National University
Nuclear and Particle Physics Proceedings | Year: 2015

The dimensional transmutation by the monopole condensation in QCD is reviewed. Using Abelian projection of the gauge potential which projects out the monopole potential gauge independently, we we show that there are two types of gluons: the color neutral binding gluons which plays the role of the confining agent and the colored valence gluons which become confined prisoners. With this we calculate the one-loop QCD effective potential and show the monopole condensation becomes the true vacuum of QCD. We propose to test the existence of two types of gluons experimentally by re-analyzing the existing gluon jets data. © 2015 Elsevier B.V.


Cho Y.,Konkuk University | Labella T.,Virginia Polytechnic Institute and State University | Lai J.-S.,Virginia Polytechnic Institute and State University | Senesky M.K.,Texas Instruments
IEEE Transactions on Industrial Electronics | Year: 2014

This paper proposes a pulsewidth-modulation strategy to achieve balanced line-to-line output voltages and to maximize the modulation index in the linear modulation range where the output voltage can be linearly adjusted in the multilevel cascaded inverter (MLCI) operating under unbalanced dc-link conditions. In these conditions, the linear modulation range is reduced, and a significant output voltage imbalance may occur as voltage references increase. In order to analyze these effects, the voltage vector space for MLCI is evaluated in detail. From this analysis, the theory behind the output voltage imbalance is explained, and the maximum linear modulation range considering an unbalanced dc-link condition is evaluated. After that, a neutral voltage modulation strategy is proposed to achieve output voltage balancing as well as to extend the linear modulation range up to the maximum reachable point in theory. In the proposed method, too large of a dc-link imbalance precludes the balancing of the output voltages. This limitation is also discussed. Both the simulations and the experiments for a seven-level phase-shifted modulated MLCI for electric vehicle traction motor drive show that the proposed method is able to balance line-to-line output voltages as well as to maximize the linear modulation range under the unbalanced dc-link conditions. © 1982-2012 IEEE.


Chung S.W.,Konkuk University | Song B.W.,Nalgae Hospital | Kim Y.H.,Anjung Seoul Jeil Hospital | Park K.U.,Seoul National University | Oh J.H.,Seoul National University
American Journal of Sports Medicine | Year: 2013

Background: The rate of healing failure after surgical repair of chronic rotator cuff tears is considerably high. Purpose: To verify the effect of platelet-rich plasma (PRP) with and without porcine dermal collagen graft augmentation on tendon-to-bone healing, using the rabbit supraspinatus tendon. Study Design: Controlled laboratory study. Methods: A total of 80 rabbits were randomly allocated into 4 groups (20 rabbits per group: 12 for histological and 8 for mechanical testing): repair (R), repair 1 patch augmentation (RPa), repair 1 PRP (RPr), and repair 1 patch 1 PRP (RPaPr). The right shoulder was used for experimental interventions, and the left served as a control. Six weeks after the detachment of the supraspinatus, the torn tendon was repaired in a transosseous manner, simulating double-row repair in all groups. Platelet-rich plasma was prepared and applied onto the repair site in the RPr and RPaPr groups, and the patch was used to augment the repair in the RPa and RPaPr groups. The mechanical tensile strength test was performed at 8 weeks after repair and the histological evaluation at 4 and 8 weeks. Results: At 4 weeks, the collagen fibers were poorly organized, and fiber continuity was not established in all groups. However, vascularity and cellularity were higher with granulation tissue formation in the PRP-treated groups (RPr and RPaPr) than the nontreated groups (R and RPa). At 8 weeks, tendon-to-bone integration was much improved with more collagen fibers, and longitudinally oriented collagen fibers were visible in all groups. The PRP-treated groups showed better collagen fiber continuity and orientation than the nontreated groups; however, no distinctive difference was found between the patch-augmented groups (RPa and RPaPr) and nonaugmented groups (R and RPr). The mean load-to-failure results were 61.57 ± 29.99 N, 76.84 ± 16.08 N, 105.35 ± 33.82 N, and 117.93 ± 12.60 N for the R, RPa, RPr, and RPaPr groups, respectively, and they were significantly different between the R and RPr (P = .018), R and RPaPr (P = .002), and RPa and RPaPr (P = .029) groups. Conclusion: This animal study showed the enhancement of tendon-to-bone healing after local administration of autologous PRP assessed by histological and biomechanical testing in a rabbit model of chronic rotator cuff tears. However, there was little additive effect of the patch graft. Clinical Relevance: The use of PRP might be a biological supplement to increase the rotator cuff healing rate, which still remains low even after successful cuff repair, but this result should be interpreted with caution regarding clinical applications. © 2013 The Author(s).


Oh J.H.,Seoul National University | Chung S.W.,Konkuk University | Kim S.H.,Seoul National University | Chung J.Y.,Seoul National University | Kim J.Y.,Myongji Hospital
Journal of Shoulder and Elbow Surgery | Year: 2014

Background: This study was conducted to verify the effects of adipose-derived stem cells (ADSCs) on tendon healing and reversal of fatty infiltration in a chronic rotator cuff tear model by using the rabbit subscapularis (SSC). Methods: The SSC insertions in 32 rabbits were cut bilaterally. After 6 weeks, secondary procedures were performed bilaterally, dividing the rabbits into 4 groups of 8 rabbits each as follows: the ADSC+repair group, saline+repair group, ADSC-only group, and saline-only group. A fifth group of 8 rabbits served as normal controls (control group). Electromyographic, biomechanical, and histologic analyses were performed 6 weeks after the secondary procedures. Results: All SSC tendons in the ADSC-only and saline-only groups failed to heal and were excluded fromthe electromyographic and biomechanical tests. On electromyographic evaluation, the ADSC+repair group exhibited a larger compound muscle action potential area than the saline+repair group (11.86 ± 2.97 ms · mV vs 9.42 ± 3.57 ms · mV, P = .029), and this response was almost at the level of the control group (13.17 ± 6.6 3 ms · mV, P = .456). Biomechanically, the load-to-failure of the ADSC+repair group (87.02 ± 29.81 N) was higher than that of the saline+repair group (59.85 ± 37.77 N), although this difference did not reach statistical significance (P = .085). Histologically, the mean proportions of fatty infiltration in the SSC muscles were 29% ± 15%, 43% ± 9%, 51% ± 14%, 63% ± 10%, and 18% ± 9% for the ADSC+repair, saline+repair, ADSC-only, saline-only, and control groups, respectively (P < .001). The degree of fat staining increased from the ADSC+repair group (unclear or weak) to the saline-only group (strongly present). Conclusion: Local administration of ADSCs might have the possibility to improve muscle function and tendon healing and decrease fatty infiltration after cuff repair. © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees.


Im J.-K.,Seoul National University | Son H.-S.,Konkuk University | Zoh K.-D.,Seoul National University
Journal of Hazardous Materials | Year: 2011

In this study, the removal of perchlorate (0.016mM) using Fe 0-only (325 mesh, 10gL -1) and Fe 0 (10gL -1) with UV (254nm) reactions were investigated under oxic and anoxic conditions (nitrogen purging). Under anoxic conditions, only 2% and 5.6% of perchlorate was removed in Fe 0-only and Fe 0/UV reactions, respectively, in a 12h period. However, under oxic conditions, perchlorate was removed completely in the Fe 0-only reaction, and reduced by 40% in the Fe 0/UV reaction, within 9h. The pseudo-first-order rate constant (k 1) was 1.63×10 -3h -1 in Fe 0-only and 4.94×10 -3h -1 in Fe 0/UV reaction under anoxic conditions. Under oxic conditions, k 1 was 776.9×10 -3h -1 in Fe 0-only reaction and 35.1×10 -3h -1 in the Fe 0/UV reaction, respectively. The chlorine in perchlorate was recovered as chloride ion in Fe 0-only and Fe 0/UV reactions, but lower recovery of chloride under oxic conditions might due to the adsorption/co-precipitation of chloride ion with the iron oxides. The removal of perchlorate in Fe 0/UV reaction under oxic conditions increased in the presence of methanol (73%, 9h), a radical scavenger, indicating that OH radical can inhibit the removal of perchlorate. The removal of perchlorate by Fe 0-only reaction under oxic condition was highest at neutral pH. Application of the Langmuir-Hinshelwood model indicated that removal of perchlorate was accelerated by adsorption/co-precipitation reactions onto iron oxides and subsequent removal of perchlorate during further oxidation of Fe 0. The results imply that oxic conditions are essential for more efficient removal of perchlorate in Fe 0/H 2O system. © 2011 Elsevier B.V.


Kim E.-H.,Konkuk University | Ro H.-M.,Seoul National University | Kim S.-L.,South Korean National Institute of Crop Science | Kim H.-S.,Chungbuk National University | Chung I.-M.,Konkuk University
Journal of Agricultural and Food Chemistry | Year: 2012

This study investigated the functional compounds, including isoflavones, phenolics, soyasapogenols, and tocopherols, that were detected in 204 soybean [Glycine max (L.) Merrill] germplasms. The soybean samples were divided into three groups according to origin: America, China, and Korea. The soybean samples were also classified into three groups on the basis of 100-seed weight: small (<13 g), medium (13-24 g), and large (>24 g). Among the soybean germplasms, CSRV121 (Bosukkong) had the highest level of isoflavone content (4778.1 μg g-1), whereas CS01316 had the lowest isoflavone content (682.4 μg g-1). Of the soybeans from the three different countries of origin, those from Korea showed the highest average concentration of total isoflavones (2252.6 μg g-1). The small seeds had the highest average total isoflavone concentration (2520.0 μg g-1) of the three different seed sizes. Among the 204 soybean germplasms, CS01405 had the highest content of total phenolics (5219.6 μg g-1), and CSRV017 (Hwangkeumkong) had the lowest phenolic content (654.6 μg g -1). The mean concentrations of total phenolic compounds were 2729.1 μg g-1 in American soybean seeds, 1680.4 μg g-1 in Chinese soybean seeds, and 1977.6 μg g-1 in Korean soybean seeds. Of the soybean seeds from the three different countries of origin, American soybean seeds had the highest average concentration of total phenolic compounds, and Korean varieties showed the second highest value. Small soybean seeds had the highest average content of total phenolic compounds (2241.7 μg g -1), whereas medium-sized (1926.8 μg g-1) and large (1949.9 μg g-1) soybeans had lower concentrations of phenolic compounds. In whole soybean germplasms, the level of total soyasapogenols was higher in CS01173 (1802.3 μg g-1) and CS01346 (1736.8 μg g -1) than in the other types of soybeans. The mean concentrations of total soyasapogenol were 1234.0 μg g-1 in American, 1294.5 μg g-1 in Chinese, and 1241.5 μg g-1 in Korean soybean varieties. Chinese soybean varieties showed the highest mean concentration of total soyasapogenol, and Korean soybean seeds showed the second highest level. The medium-seed group had the highest soyasapogenol content (1269.3 μg g -1) of the seeds that were grouped by size. A larger amount of soyasapogenol B than soyasapogenol A was detected. In whole soybeans, CS01202 showed the highest level of total tocopherols (330.5 μg g-1), whereas CSRV056 (Pungsannamulkong) had the lowest content (153.3 μg g -1). Chinese soybeans had the highest average concentration of total tocopherols (255.1 μg g-1). By comparison, the medium-sized Chinese soybean group had the highest (256.1 μg g-1) average total tocopherol content. © 2012 American Chemical Society.


Kim S.-K.,Konkuk University | Park J.H.,Seoul National University
Journal of Ginseng Research | Year: 2011

A total of 470 papers directly related to research on the Panax species were retrieved by performing internet searches with the keywords Panax and ginseng as the search terms. The publications were categorized as follows: 399 research articles, 30 reviews, 30 meeting abstracts, 7 proceedings, and 4 letters. The majority of these publications were published by scientists from Korea (35.7%), China (32.3%), and the USA (11.3%). Scientists from a total of 29 nations were actively involved in conducting ginseng research. A total of 43.6% of the publications were categorized as pharmacodynamic studies. The effects of ginseng on cerebrovascular function and cancer were the two most common topics considered in the pharmacodynamic studies. More than half of the ginseng studies assessed the use of P. ginseng. A total of 23 countries participated in studies specifically related to P. ginseng, and more than 80% of these studies originated from Korea and China. A total of 50 topics within the pharmacodynamics category were examined in association with the use of P. ginseng. © The Korean Society of Ginseng.


Seo M.,Seoul National University | Kim S.K.,Seoul National University | Min Y.-S.,Konkuk University | Hwang C.S.,Seoul National University
Journal of Materials Chemistry | Year: 2011

HfO2 films were grown by atomic layer deposition (ALD) using a new heteroleptic hafnium precursor, tert-butoxytris(ethylmethylamido)hafnium (BTEMAH), and ozone. This BTEMAH precursor achieved a very high growth rate and retained excellent thermal stability in electrical performance due to the high film density of the HfO2 films. Additionally, the structural compatibility between the specific planes of tetragonal HfO2 and rutile TiO2 achieved a high dielectric constant (∼29) for HfO2 films grown on a rutile TiO2 film. It is demonstrated that this BTEMAH is a very promising precursor for the growth of HfO 2 films for both the applications of a gate oxide and a capacitor dielectric. © 2011 The Royal Society of Chemistry.


Cho Y.M.,Konkuk University | Cho Y.M.,Seoul National University | Cho F.H.,University of Southern California | Yoon J.H.,Konkuk University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We compare two competing conjectures of the color confinement in QCD, the monopole condensation and the Abelian dominance, and show that it is the monopole condensation that is responsible for the confinement. To demonstrate this we present a new gauge-invariant integral expression of the one-loop QCD effective action which has no infrared divergence. With this we show that, just as the Gliozzi-Scherk-Olive projection restores the supersymmetry and modular invariance in NSR string theory, the color reflection invariance ("the C projection") assures the gauge invariance and the stability of the monopole condensation. This establishes the monopole dominance in QCD. In doing so we point out critical defects in the calculation of the Savvidy-Nielsen-Olesen effective action. © 2013 American Physical Society.


Chon D.-H.,University of Massachusetts Amherst | Rome M.,University of Massachusetts Amherst | Kim Y.M.,University of Massachusetts Amherst | Park K.Y.,Konkuk University | Park C.,University of Massachusetts Amherst
Water Research | Year: 2011

To investigate the mechanism of sludge reduction in the anaerobic side-stream reactor (SSR) process, activated sludge with five different sludge reduction schemes were studied side-by-side in the laboratory. These are activated sludge with: 1) aerobic SSR, 2) anaerobic SSR, 3) aerobic digester, 4) anaerobic digester, and 5) no sludge wastage. The system with anaerobic SSR (system #2) was the focus of this study and four other systems served as control processes with different functions and purposes. Both mathematical and experimental approaches were made to determine solids retention time (SRT) and sludge yield for the anaerobic SSR process. The results showed that the anaerobic SSR process produced the lowest solids generation, indicating that sludge organic fractions degraded in this system are larger than other systems that possess only aerobic or anaerobic mode. Among three systems that involved long SRT (system #1, #2, and #5), it was only system #2 that showed stable sludge settling and effluent quality, indicating that efficient sludge reduction in this process occurred along with continuous generation of normal sludge flocs. This observation was further supported by batch anaerobic and aerobic digestion data. Batch digestion on sludges collected after 109 days of operation clearly demonstrated that both anaerobically and aerobically digestible materials were removed in activated sludge with anaerobic SSR. In contrast, sludge reduction in the aerobic SSR process or no wastage system was achieved by removal of mainly aerobically digestible materials. All these results led us to conclude that repeating sludge under both feast/fasting and anaerobic/aerobic conditions (i.e., activated sludge with anaerobic SSR) is necessary to achieve the highest biological solids reduction with normal wastewater treatment performance. © 2011 Elsevier Ltd.


Lee K.W.,Konkuk University | Lee K.W.,Seoul National University | Bode A.M.,University of Minnesota | Dong Z.,University of Minnesota
Nature Reviews Cancer | Year: 2011

Although successful for a limited number of tumour types, the efficacy of cancer therapies, especially for late-stage disease, remains poor overall. Many have argued that this could be avoided by focusing on cancer prevention, which has now entered the arena of targeted therapies. During the process of identifying preventive agents, dietary phytochemicals, which are thought to be safe for human use, have emerged as modulators of key cellular signalling pathways. The task now is to understand how these chemicals perturb these pathways by modelling their interactions with their target proteins. © 2011 Macmillan Publishers Limited. All rights reserved.


Park Y.M.,Johns Hopkins University | Park Y.M.,Konkuk University | Bochner B.S.,Johns Hopkins University
Allergy, Asthma and Immunology Research | Year: 2010

Eosinophilia is common feature of many disorders, including allergic diseases. There are many factors that influence the production, migration, survival and death of the eosinophil. Apoptosis is the most common form of physiological cell death and a necessary process to maintain but limit cell numbers in humans and other species. It has been directly demonstrated that eosinophil apoptosis is delayed in allergic inflammatory sites, and that this mechanism contributes to the expansion of eosinophil numbers within tissues. Among the proteins known to influence hematopoiesis and survival, expression of the cytokine interleukin-5 appears to be uniquely important and specific for eosinophils. In contrast, eosinophil death can result from withdrawal of survival factors, but also by activation of pro-apoptotic pathways via death factors. Recent observations suggest a role for cell surface death receptors and mitochondria in facilitating eosinophil apoptosis, although the mechanisms that trigger each of these death pathways remain incompletely delineated. Ultimately, the control of eosinophil apoptosis may someday become another therapeutic strategy for treating allergic diseases and other eosinophil-associated disorders. © Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology • The Korean Academy of Pediatric Allergy and Respiratory Disease.


Park J.S.,Konkuk University | Baek A.,Konkuk University | Park I.-S.,Seoul National University | Jun B.-H.,Konkuk University | Kim D.-E.,Konkuk University
Chemical Communications | Year: 2013

We report a simple, direct fluorometric assay based on graphene oxide (GO) for RNA polymerase-mediated RNA synthesis. In principle, fluorescent peptide nucleic acid (PNA) probes were designed, and annealed with RNA products and the resultant RNA-PNA hybrids induced the recovery of fluorescence intensity of the PNA probes adsorbed onto the GO surface. © 2013 The Royal Society of Chemistry.


Lee S.-W.,Pusan National University | Kouba J.,Natural Resources Canada | Schutz B.,University of Texas at Austin | Kim D.H.,National Meteorological Satellite Center | Lee Y.J.,Konkuk University
Journal of Geodesy | Year: 2013

This paper addresses real-time monitoring of the precipitable water vapor (PWV) from GNSS measurements and presents some results obtained from 6-month long GNSS PWV experiments using international and domestic GNSS networks. In the real-time GNSS PWV monitoring system a server/client structure is employed to facilitate formation of PWV networks and single-differenced GNSS measurements are utilized to mitigate errors in GNSS satellites' orbits and clocks. An issue relating to baseline length between the server and clients is discussed in detail and as a result the PWV monitor is configured to perform in two modes depending on the baseline length. The server estimates sequentially the zenith wet delay of the individual stations, which is then converted into the PWV of the stations. We evaluate system performance by comparing the real-time PWV solution with reference solutions including meteorological measurements obtained with radiosondes and deferred-time precision GNSS PWV solutions. Results showed that the standard deviation of difference between the real-time PWV and the reference solutions ranged from 2.1 to 3.4 mm in PWV for a 6-month long comparison, which was improved to 1.4 to 2.9 mm by reducing comparison period to 20 days in winter. © 2013 Springer-Verlag Berlin Heidelberg.


Tahir M.N.,Konkuk University | Lee Y.,Seoul National University
Food Chemistry | Year: 2013

β-Cyclodextrin (β-CD) was converted into β-CD-N3 by chemical modification and subsequently attached covalently on glass surface by click reaction. Functionalised glass surface was characterised by static water contact angle and X-ray photoelectron spectroscopy (XPS). Both techniques show that β-CD was successfully attached on glass surface. β-CD on solid surface was used to make a complexation with cholesterol to remove it from milk. 69 ± 1% cholesterol was reduced in 4 h at 25 °C and 170 rpm. The same surface was used repeatedly for eight cycles and it maintained its efficiency, with 68 ± 2% cholesterol reduction. Modified glass surface showed almost no degradation as confirmed from XPS analysis after eight cycles of repeated use in cholesterol reduction experiments. The high efficiency and stability of functional monolayer was attributed to its specific structure with relatively low number of functional groups and longer spacer chain length to providing higher flexibility to β-CD molecules. © 2013 Elsevier Ltd. All rights reserved.


Jeong H.-J.,Seoul National University | Kim Y.-G.,Soongsil University | Yang Y.-H.,Konkuk University | Kim B.-G.,Seoul National University
Analytical Chemistry | Year: 2012

Accurate and reproducible quantification of glycans from protein drugs has become an important issue for quality control of therapeutic proteins in biopharmaceutical and biotechnology industries. Mass spectrometry is a promising tool for both qualitative and quantitative analysis of glycans owing to mass accuracy, efficiency, and reproducibility, but it has been of limited success in quantitative analysis for sialylated glycans in a high-throughput manner. Here, we present a solid-phase permethylation-based total N-glycan quantitative method that includes N-glycan releasing, purification, and derivatization on a 96-well plate platform. The solid-phase neutralization enabled us to perform reliable absolute quantification of the acidic N-glycans as well as neutral N-glycans from model glycoproteins (i.e., chicken ovalbumin and porcine thyroglobulin) by only using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Furthermore, low-abundance sialylated N-glycans from human serum prostate specific antigen (PSA), an extremely valuable prostate cancer marker, were initially quantified, and their chemical compositions were proposed. Taken together, these results demonstrate that our all-inclusive glycan preparation method based on a 96-well plate platform may contribute to the precise and reliable qualitative and quantitative analysis of glycans. © 2012 American Chemical Society.


Han J.-Y.,Seoul National University | Han S.-H.,Konkuk University
Journal of Korean Medical Science | Year: 2014

Alzheimer's disease (AD) is the leading cause of dementia, and the most prevalent neurodegenerative disease in the elderly. The prevalence of AD is predicted to rise as life expectancy grows across populations. The exact cause of this devastating disease is still unknown; however, it is an aging-related multi-factorial disorder, and growing evidence supports the contribution of modifiable environmental factors to unmodifiable factors such as gene and ageing itself. The recent advancement of methodologies and techniques for early diagnosis of AD facilitates the investigation of strategies to reduce the risk for AD progression in the earliest stages of the disease. Pharmacological attempts at curing, halting or modifying it have, by and large, been unsuccessful, and no breakthrough is seen in the near future. However, a lot of elements that seem to contribute to the disease such as risk factors have been identified, mainly from epidemiological and basic research studies. Many of these are amenable to lifestyle modification. Therefore, prevention in the preclinical stage is likely the most effective way to decrease the incidence of this age-associated dreadful neurodegenerative condition, and its associated burden for individuals and society. We provide an overview of modifiable risk factors for AD along with the supporting evidence. © 2014 The Korean Academy of Medical Sciences.


Hwan Ko J.,Seoul National University | Byun D.,Konkuk University
Computers and Structures | Year: 2010

Mid-frequency response analysis often faces computational difficulties when a conventional modal approach is used for a finite element linear system. In this paper, the computational burden is relieved by frequency sweep algorithm or mode acceleration method for a reduced-order system constructed by algebraic substructuring, a variant of model order reduction. The two methods are compared with the help of numerical experiments and their computational complexity. As demonstrated by the finite element simulations, in which proportional damping is assumed, of a turbo-prop aircraft and a ring resonator, the frequency sweep algorithm for reduced-order systems shows the best performance among all considered numerical solutions, including the conventional approach. © 2009 Elsevier Ltd. All rights reserved.


Pai J.,Yonsei University | Yoon T.,Yonsei University | Kim N.D.,Daegu Gyeongbuk Medical Innovation Foundation | Lee I.-S.,Konkuk University | And 2 more authors.
Journal of the American Chemical Society | Year: 2012

A rapid and quantitative method to evaluate binding properties of hairpin RNAs to peptides using peptide microarrays has been developed. The microarray technology was shown to be a powerful tool for high-throughput analysis of RNA-peptide interactions by its application to profiling interactions between 111 peptides and six hairpin RNAs. The peptide microarrays were also employed to measure hundreds of dissociation constants (Kd) of RNA-peptide complexes. Our results reveal that both hydrophobic and hydrophilic faces of amphiphilic peptides are likely involved in interactions with RNAs. Furthermore, these results also show that most of the tested peptides bind hairpin RNAs with submicromolar Kd values. One of the peptides identified by using this method was found to have good inhibitory activity against TAR-Tat interactions in cells. Because of their great applicability to evaluation of nearly all types of RNA-peptide interactions, peptide microarrays are expected to serve as robust tools for rapid assessment of peptide-RNA interactions and development of peptide ligands against RNA targets. © 2012 American Chemical Society.


Lee D.,University of Minnesota | Lee D.,Konkuk University | Cui T.,University of Minnesota
Microelectronic Engineering | Year: 2012

Carboxylated single-walled carbon nanotube thin-film (SWCNT-TF) is demonstrated as a pH electrode and a platform for enzymatic potentiometric acetylcholine biosensors. SWCNT is layer-by-layer assembled with a positively charged polyelectrolyte on the metal electrode. The open circuit potential on SWCNT-TF electrode is measured with reference to an Ag/AgCl electrode in various pH buffers. With the aid of acetylcholinesterase (AchE), acetylcholine (Ach) is successfully detected using the SWCNT-TF pH electrode that demonstrates Nernst potential of -43 mV/pH. AchE-modified electrode has a sensing resolution of 10 μM of Ach and sensitivity of 19 mV/decade. The SWCNT-TF pH electrode fabricated by layer-by-layer self-assembly may play an important role in micro/nanoscale electrochemical sensors. © 2011 Elsevier B.V. All rights reserved.


Um T.-H.,Yonsei University | Kim H.,Seoul National University | Oh B.-K.,Konkuk University | Kim M.S.,Yonsei University | And 3 more authors.
Journal of Hepatology | Year: 2011

Background & Aims: The concept of multistep hepatocarcinogenesis has been well-established, and an accumulation of methylating events has recently been demonstrated; however, the methylation status of low-grade dysplastic nodules (LGDN), high-grade dysplastic nodules (HGDN), and the recently introduced early hepatocellular carcinoma (eHCC) in hepatitis B virus (HBV)-related hepatocarcinogenesis has not yet been studied. Methods: One hundred thirty-three DNA samples (45 cirrhotic nodules, 29 LGDNs, 13 HGDNs, 14 eHCCs, and 32 progressed HCCs (pHCCs)) from HBV-infected resected livers were subjected to MethyLight analysis for nine CpG island loci (APC, RASSF1A, SOCS1, P16, COX2, SPRY2, PTEN, GNMT, and ERK), and COX2, RASSF1A, and SOCS1 protein expression status was analyzed by immunohistochemistry. The methylation status of each sample was correlated with the clinicopathological features. Results: APC, RASSF1A, and SOCS1 were methylated in 20 (44.4%), 25 (55.6%), and 13 (28.9%) of 45 cirrhosis samples, and APC (p = 0.0008) and SOCS1 (p = 0.0187) methylation were more frequent in dysplastic nodules and HCCs. APC (p = 0.001) and RASSF1A (p = 0.019) methylation levels were significantly increased from cirrhosis to LGDN. SOCS1 methylation gradually increased along multistep hepatocarcinogenesis, peaked at eHCC and decreased significantly in pHCCs (p = 0.039). By contrast, p16 and COX2 was only methylated in dysplastic nodules and HCCs, with a stepwise increase up to pHCCs. As a whole, the frequency of methylation was highest in eHCCs. A stepwise decrease in COX2, RASSF1A, and SOCS1 protein expression was demonstrated. Conclusions: A general stepwise increase in methylating events is seen during HBV-related multistep hepatocarcinogenesis, and epigenetic changes may occur predominantly in the earlier stages of HCC development. © 2010 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.


Hong S.W.,Korea Institute of Science and Technology | Kim H.S.,Konkuk University | Chung T.H.,Seoul National University
Environmental Pollution | Year: 2010

The alteration of physico-chemical properties of sediment organic matter (SOM) incubated under current-harvesting conditions as well as no-current producing conditions over 120 days using sediment microbial fuel cell systems was examined. The SOM was microbially oxidized under anaerobic conditions with an electrode serving as a terminal electron acceptor. It was found that SOM around the electrochemically-active electrodes became more humified, aromatic, and polydispersed, and had a higher average molecular weight, along with its partial degradation and electricity generation compared to that for the original sediment. These changes in SOM properties were analogous to those commonly observed in the early stages of the SOM diagenetic process (i.e. humification). Such a humification-like process was evidently more stimulated when electrical current was produced than no-current condition. These new findings associated with microbially-catalyzed electricity generation may present a potential for the energy-efficient remediation, monitoring, and/or management of the geo-environment. © 2009 Elsevier Ltd. All rights reserved.


Seo M.-D.,Ajou University | Won H.-S.,Konkuk University | Kim J.-H.,Vanderbilt University | Mishig-Ochir T.,National University of Mongolia | Lee B.-J.,Seoul National University
Molecules | Year: 2012

Antimicrobial peptides (AMPs) have been considered as potential therapeutic sources of future antibiotics because of their broad-spectrum activities and different mechanisms of action compared to conventional antibiotics. Although AMPs possess considerable benefits as new generation antibiotics, their clinical and commercial development still have some limitations, such as potential toxicity, susceptibility to proteases, and high cost of peptide production. In order to overcome those obstacles, extensive efforts have been carried out. For instance, unusual amino acids or peptido-mimetics are introduced to avoid the proteolytic degradation and the design of short peptides retaining antimicrobial activities is proposed as a solution for the cost issue. In this review, we focus on small peptides, especially those with less than twelve amino acids, and provide an overview of the relationships between their three-dimensional structures and antimicrobial activities. The efforts to develop highly active AMPs with shorter sequences are also described. © 2012 by the authors; licensee MDPI, Basel, Switzerland.


Kang S.-C.,Korea Advanced Institute of Science and Technology | Koh H.-M.,Seoul National University | Choo J.F.,Konkuk University
Probabilistic Engineering Mechanics | Year: 2010

The response surface method (RSM) is widely adopted for structural reliability analysis because of its numerical efficiency. However, the RSM is time consuming for large-scale applications and sometimes shows large errors in the calculation of the sensitivity of the reliability index with respect to random variables. In order to overcome these problems, this study proposes an efficient RSM applying a moving least squares (MLS) approximation instead of the traditional least squares approximation generally used in the RSM. The MLS approximation gives higher weight to the experimental points closer to the most probable failure point (MPFP), which allows the response surface function (RSF) to be closer to the limit state function at the MPFP. In the proposed method, a linear RSF is constructed at first and a quadratic RSF is formed using the axial experimental points selected from the reduced region where the MPFP is likely to exist. The RSF is updated successively by adding one new experimental point to the previous set of experimental points. Numerical examples are presented to demonstrate the improved accuracy and computational efficiency of the proposed method compared to the conventional RSM. © 2010 Elsevier Ltd. All rights reserved.


Kim W.,Samsung | Chattopadhyay D.,Saha International | Park J.-B.,Konkuk University
Energy | Year: 2010

Carbon costs - either in the form of a carbon tax or through permit prices in an emissions trading scheme - would ultimately be reflected in higher electricity prices. Carbon cost "pass-through" is critical to the survival of existing coal generation assets and has been discussed widely as a measure of business impact in the electricity industry. This paper sets out in a structured way the factors that determine price pass-through and why this may differ greatly across different systems. Although the basic concept of price pass-through is simple, a clear understanding of the underlying factors is critical to developing insights on how carbon cost would impact on existing coal generation businesses. It is shown that pass-through can vary drastically if the underlying dispatch potential of generators varies significantly across alternative emissions reduction scenarios. It can also vary depending on the availability of competing cleaner forms of generation. Pass-through as a measure of business performance is, therefore, hard to generalize across different circumstances and should be interpreted carefully. © 2010 Elsevier Ltd.


Kim Y.,Konkuk University | Othmer H.G.,University of Minnesota
Bulletin of Mathematical Biology | Year: 2013

Ductal carcinoma in situ (DCIS) is an early stage noninvasive breast cancer that originates in the epithelial lining of the milk ducts, but it can evolve into comedo DCIS and ultimately, into the most common type of breast cancer, invasive ductal carcinoma. Understanding the progression and how to effectively intervene in it presents a major scientific challenge. The extracellular matrix (ECM) surrounding a duct contains several types of cells and several types of growth factors that are known to individually affect tumor growth, but at present the complex biochemical and mechanical interactions of these stromal cells and growth factors with tumor cells is poorly understood. Here we develop a mathematical model that incorporates the cross-talk between stromal and tumor cells, which can predict how perturbations of the local biochemical and mechanical state influence tumor evolution. We focus on the EGF and TGF-β signaling pathways and show how up- or down-regulation of components in these pathways affects cell growth and proliferation. We then study a hybrid model for the interaction of cells with the tumor microenvironment (TME), in which epithelial cells (ECs) are modeled individually while the ECM is treated as a continuum, and show how these interactions affect the early development of tumors. Finally, we incorporate breakdown of the epithelium into the model and predict the early stages of tumor invasion into the stroma. Our results shed light on the interactions between growth factors, mechanical properties of the ECM, and feedback signaling loops between stromal and tumor cells, and suggest how epigenetic changes in transformed cells affect tumor progression. © 2012 Society for Mathematical Biology.


Heo J.,Samsung | Byun K.-E.,Samsung | Lee J.,Samsung | Chung H.-J.,Samsung | And 5 more authors.
Nano Letters | Year: 2013

Graphene heterostructures in which graphene is combined with semiconductors or other layered 2D materials are of considerable interest, as a new class of electronic devices has been realized. Here we propose a technology platform based on graphene-thin-film-semiconductor-metal (GSM) junctions, which can be applied to large-scale and power-efficient electronics compatible with a variety of substrates. We demonstrate wafer-scale integration of vertical field-effect transistors (VFETs) based on graphene-In-Ga-Zn-O (IGZO)-metal asymmetric junctions on a transparent 150 × 150 mm2 glass. In this system, a triangular energy barrier between the graphene and metal is designed by selecting a metal with a proper work function. We obtain a maximum current on/off ratio (Ion/Ioff) up to 106 with an average of 3010 over 2000 devices under ambient conditions. For low-power logic applications, an inverter that combines complementary n-type (IGZO) and p-type (Ge) devices is demonstrated to operate at a bias of only 0.5 V. © 2013 American Chemical Society.


Kim J.-M.,Seoul National University | Won H.-S.,Konkuk University | Kang S.-O.,Seoul National University
Proteins: Structure, Function and Bioinformatics | Year: 2014

BldD regulates transcription of key developmental genes in Streptomyces coelicolor. While the N-terminal domain is responsible for both dimerization and DNA binding, the structural and functional roles of the C-terminal domain (CTD) remain largely unexplored. Here, the solution structure of the BldD-CTD shows a novel winged-helix domain fold not compatible with DNA binding, due to the negatively charged surface and presence of an additional helix. Meanwhile, a small elongated groove with conserved hydrophobic patches surrounded by charged residues suggests that the BldD-CTD could be involved in protein-protein interactions that provide transcriptional regulation. © 2013 Wiley Periodicals, Inc.


Sprague I.B.,Washington State University | Byun D.,Konkuk University | Dutta P.,Washington State University | Dutta P.,Konkuk University
Electrochimica Acta | Year: 2010

A mathematical model is developed to simulate the performance of a laminar flow fuel cell with reactant crossover using the Poisson-Nernst-Plank (PNP) equations. The model includes a more general treatment of reactant (fuel or oxidant) crossover than the common method where it is assumed that the crossover flux is fully utilized as crossover current. This new model allows for the analysis of very narrow channels and estimation of parasitic crossover current at both the anode and the cathode. It also allows for the consideration of a laminar flow fuel cell with a significant amount of reactant crossover where the crossover species are not fully consumed by the crossover current. Moreover, the combination of the PNP equations and the general reactant crossover treatment reveal the two-dimensional developing region for electrode mixed potentials which is a novel result. The parameters considered in this study are electrode length and separation (channel height). Numerical results show that the reactant crossover, transport limitations, and Ohmic losses are the primary performance limitation factors. The current distributions along the anode and cathode are presented as well as the reactant concentrations at the anode as evidence of these performance limitations. It is also shown that the fluid velocity field, as it changes with channel height, plays a small role in the development of the depletion boundary layer. © 2010 Elsevier Ltd All rights reserved.


Paik H.-D.,Konkuk University | Lee J.-Y.,KOR Livestock Products HACCP Accreditation Service
Meat Science | Year: 2014

Lactobacillus brevis KGR3111, Lactobacillus curvatus KGR 2103, Lactobacillus plantarum KGR 5105, and Lactobacillus sakei KGR 4108 isolated from kimchi were investigated for their potential to be used as starter culture for fermented sausages with the capability to reduce and tolerate nitrate/nitrite. The reduction capability of tested strains for nitrate was not dramatic. All tested strains, however, showed the capability to produce nitrite reductase with the reduction amount of 58.46-75.80mg/l of NO2-. L. brevis and L. plantarum showed nitrate tolerance with the highest number of 8.71logcfu/ml and 8.81logcfu/ml, and L. brevis and L. sakei exhibited nitrite tolerance with the highest number of 8.24logcfu/ml and 8.25logcfu/ml, respectively. As a result, L. brevis, L. plantarum, and L. sakei isolated from kimchi showed a tolerance against nitrate or nitrite with a good nitrite reduction capability, indicating the satisfaction of one of the selection criteria to be used as starter culture for fermented sausages. © 2014 Elsevier Ltd.


Lee J.,Konkuk University | Chung T.D.,Seoul National University | Yeo W.-S.,Konkuk University
Analytica Chimica Acta | Year: 2012

This paper reports on analyses of small molecules with laser desorption/ionization time of flight (LDI-TOF) mass spectrometry (MS) using nanostructure-embedded micro gold shells (μAuSs). The mass analyses of amino acids, sugars, peptides, and their mixtures gave apparent mass peaks for analytes without any significant background interferences. μAuSs afforded a better limit of detection (LOD) and a higher signal-to-noise ratio than gold nanoparticles, which are commonly used for LDI-TOF analysis of small molecules. We believe μAuSs have advantages in terms of simplicity, detection limit, and reproducibility, and therefore, they constitute a significant addition to the organic matrix-free analytical tools that are currently in wide use. © 2012 Elsevier B.V.


Chung S.W.,Konkuk University | Kim J.Y.,Myongji Hospital | Kim M.H.,Seoul National University | Kim S.H.,Seoul National University | Oh J.H.,Seoul National University
American Journal of Sports Medicine | Year: 2013

Background: Many patients with an unhealed cuff after repair show functional improvement. Purpose: To evaluate outcomes of arthroscopically repaired massive rotator cuff tears and to identify prognostic factors affecting rotator cuff healing and functional outcome, especially in patients with failed rotator cuff healing. Study Design: Case series; Level of evidence, 4. Methods: Among 173 patients who underwent arthroscopic repair of a massive rotator cuff tear, 108 patients with a mean age of 63.7 years were included. Outcome evaluation was completed both anatomically (CT arthrography or ultrasonography) and functionally at a minimum of 1 year postoperatively; mean follow-up period was 31.68 6 15.81 months. Various factors affecting cuff healing were analyzed, and factors affecting functional outcome were evaluated in patients with failed repairs using both univariate and multivariate analyses. Results: The anatomic failure rate was 39.8% in arthroscopically repaired massive rotator cuff tears; however, functional status significantly improved regardless of cuff healing (P\.05). Several factors were associated with failure of cuff healing in the univariate analysis, but only fatty infiltration (FI) of the infraspinatus was significantly related to healing failure in the multivariate analysis (P = .04). Among patients with failed rotator cuff healing, only reduced postoperative acromiohumeral distance (AHD) was related to poor functional outcome in the multivariate analysis (P = .01), with a cutoff value of 4.1 mm. Conclusion: Despite a high rate of healing failures, arthroscopic repair can be recommended in patients with massive rotator cuff tears because of the functional gain at midterm follow-up. Higher FI of the infraspinatus was the single most important factor negatively affecting cuff healing. In cases of failed massive rotator cuff repair, no preoperative factor was able to predict poor functional outcome; reduced postoperative AHD was the only relevant functional determinant in the patients eventual functional outcome and should be considered when ascertaining a prognosis and planning further treatment strategies. © 2013 The Author(s).


Yang J.-H.,Seoul National University | Myoung N.,Konkuk University | Hong H.-G.,Seoul National University
Electrochimica Acta | Year: 2012

This work describes a new Prussian blue (PB)-based electrochemical sensor based on chitosan (CS)-functionalized graphene nanosheets which exhibit good dispersibility and stability in aqueous solution. The morphology and composition of the graphene-CS/PB nanocomposite sheets were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The electrochemical behavior of the resulting sensor was investigated using cyclic voltammetry and amperometry. The modified sensor showed good electrocatalytic activity in the reduction of hydrogen peroxide and was used as an amperometric sensor. The sensor exhibited a linear response for H 2O 2 over concentrations ranging from 0.01 to 0.4 mM with a high sensitivity of 816.4 μA/(mM cm 2) and a low detection limit (S/N = 3) of 0.213 μM. These parameters compare favorably with other PB-based electrodes. Furthermore, the new sensor exhibited freedom from interference from other co-existing electroactive species in human blood. This work describes a new type of graphene nanocomposite-modified electrode for amperometric biosensors. © 2012 Elsevier Ltd. All rights reserved.


Chun H.,State University of New York at Buffalo | Lee H.,Konkuk University | Kim D.,State University of New York at Buffalo
Cyberpsychology, Behavior, and Social Networking | Year: 2012

This study aims to propose an integrated model of smartphone adoption that incorporates social influences (SIs), perceived technicality, as well as hedonic and utilitarian attitudes into the technology acceptance model. The proposed model was empirically evaluated by using survey data collected from 239 Korean college students to investigate their perception and attitudes toward smartphone adoption intention. Our results show that users' attitudes and their adoption intention are highly influenced by SI and positive self-image. This implies that a smartphone is a symbolic product that can signal affiliation and enhance the users' status in a group. The results also indicate that hedonic enjoyment is equally important as utilitarian usefulness in predicting the adoption intention, and the two variables mediate the relationships between SI, positive self-image, perceived technicality, and the intention to use. Consequently, the results reveal that smartphones are convergent media that can be viewed as both task-oriented and entertainment-oriented devices. © Copyright 2012, Mary Ann Liebert, Inc.


Hossan M.R.,Washington State University | Byun D.,Konkuk University | Dutta P.,Washington State University | Dutta P.,Konkuk University
International Journal of Heat and Mass Transfer | Year: 2010

Microwave heating is very popular in food industries as well as in home and office to warm up foodstuffs quickly. However, this technique provides non-uniform heating within the system. The potential existence of standing wave due to the transmission and reflection from interfaces is responsible for this non-uniform heating. Therefore, it is important to study the coupling between electromagnetic wave propagation and energy transfer in the system to predict the temperature distribution within the foodstuff. In this paper, a closed-form analytic solution is presented to predict the temperature distribution within a cylindrical shaped foodstuff under microwave heating by solving an unsteady energy equation. A simplified Maxwell's equation is solved for electric field distribution within the body. The heat generation by microwave is calculated from the electric field distribution within the body using Poynting theorem. The effects of cylinder radius, heat transfer coefficient and incident frequency are studied for different length of the cylindrical foodstuff. It is found that the temperature within the body is very sensitive to cylinder length and time. The results indicate that uniform and effective heating depend on the proper integration of geometric parameters and dielectric properties of the object as well as the frequency of the incident electromagnetic wave. This rigorous analytic investigation will provide significant insight to understand and overcome the challenge of non-uniformity in temperature distribution in microwave heating. © 2010 Elsevier Ltd. All rights reserved.


Chang A.,Seoul National University | Eo Y.,Konkuk University | Kim Y.,Seoul National University
Remote Sensing Letters | Year: 2013

In this study, we propose an algorithm for identifying tree crowns from LiDAR data based on the geometric relationship between local maxima and minima in forests. The local maxima and minima of LiDAR data were extracted as tree tops and crown boundaries, respectively. The most reasonable circles estimated from four local minima closest to the tree top were fitted as tree crowns. We identified 77% of the reference tree crowns using LiDAR data from dense and mixed forests in Korea, with a point density of approximately 4.3 points/m 2. The regression line between the results and the field data indicated the underestimation of tree height and crown diameter. Further work is needed to establish the influence of forest conditions and data with higher point densities. © 2012 Taylor & Francis.


Heo S.W.,Konkuk University | Song I.S.,Samsung | Kim Y.S.,Seoul National University of Science and Technology | Moon D.K.,Konkuk University
Solar Energy Materials and Solar Cells | Year: 2012

Organic photovoltaic cells (OPVs) with a conductivity enhanced by doping with either dimethylsulfoxide (DMSO) or ethylene glycol (EG) were successfully fabricated to increase the photon harvesting property through localized surface plasmon resonance (LSPR) by adding Au nanoparticles to PH500, a hole collection layer, and effectively separating the generated charges. At Au nanoparticle and DMSO doping concentrations of 20 wt% and 1 wt%, respectively, the characteristics of the OPVs were optimized with a short-circuit current density (J sc), open-circuit voltage (V oc), fill factor (FF) and estimated power conversion efficiency (PCE) of 8.0 mA/cm 2, 0.595 V, 57.8% and 2.6%, respectively. Compared to the device with a buffer layer of conventional PEDOT:PSS, PCE was improved by ca. 85%. The series resistance (R s), shunt resistance (R sh), and hole mobility were 18 Ω cm 2, 673 Ω cm 2 and 4.2 cm 2/Vs, respectively. © 2012 Elsevier B.V. All rights reserved.


Patent
Konkuk University, Electronics and Telecommunications Research Institute | Date: 2012-08-20

A digital phase-locked loop apparatus using FSK includes a PFD detecting phase differences between a reference clock and a frequency-divided signal, and a first adder for generating first digital control codes by adding first digital codes, second digital codes, and channel frequency codes including channel information to each other, the first digital codes being converted from time differences between first and second pulses. The apparatus further includes a digital filter correcting errors of the first digital control codes to generate second digital control codes, a DCO for varying an oscillating frequency in accordance with a digital tuning word based on the second digital control codes, and a dual modulus division unit dividing the oscillating frequency into a frequency-divided signal.


Patent
Electronics, Telecommunications Research Institute and Konkuk University | Date: 2014-07-18

Provided is a gate driver circuit. The gate driver circuit includes a plurality of sequentially connected stages, and each of stages includes an input unit including two input transistors forming diode connection, a pull-up unit including a pull-up transistor and a bootstrap capacitor, and first and second pull-down units each including two transistors. According to embodiments, an input capacitor is further included which is connected to a node between the input unit and the pull-up unit. In addition, a carry unit is further included which is connected to an output terminal and formed to transmit an output signal in a high state or a low state to a next stage.


Patent
Konkuk University, Electronics and Telecommunications Research Institute | Date: 2013-10-09

Disclosed are an inverter, a NAND gate, and a NOR gate. The inverter includes: a pull-up unit constituted by a second thin film transistor outputting a first power voltage to an output terminal according to a voltage applied to a gate; a pull-down unit constituted by a fifth thin film transistor outputting a ground voltage to the output terminal according to an input signal applied to a gate; and a pull-up driver applying a second power voltage or the ground voltage to the gate of the second thin film transistor according to the input signal.


Patent
Konkuk University, Electronics and Telecommunications Research Institute | Date: 2013-10-09

Disclosed are an inverter, a NAND gate, and a NOR gate. The inverter includes: a pull-up unit constituted by a second thin film transistor outputting a first power voltage to an output terminal according to a voltage applied to a gate; a pull-down unit constituted by a fifth thin film transistor outputting a ground voltage to the output terminal according to an input signal applied to a gate; and a pull-up driver applying a second power voltage or the ground voltage to the gate of the second thin film transistor according to the input signal.


Provided herein is a gas barrier film having excellent flexibility and an excellent gas barrier characteristic at the same time and a refrigerator having the same. Provided herein is a method of manufacturing a gas barrier film. The gas barrier film includes an organic-inorganic mixed layer on which a first organic-inorganic hybrid layer including a first organic part and a first inorganic part and an aluminum oxide layer are laminated. The gas barrier film also includes a second organic-inorganic hybrid layer including a second organic part and a second inorganic part. The gas barrier film further includes a substrate on which the organic-inorganic mixed layer and the second organic-inorganic hybrid layer are laminated.


Patent
Konkuk University and Samsung | Date: 2012-01-19

Memory mapping in small units using a segment and subsegments is described, and thus it is possible to control a memory access even using a small amount of hardware, and it is possible to reduce costs incurred by hardware. Additionally, it is possible to prevent a memory from being destroyed due to a task error in the multi-processor system.


Patent
Electronics, Telecommunications Research Institute and Konkuk University | Date: 2013-08-27

Provided is a single input level shifter. The single input level shifter includes: an input unit applying a power voltage to a first node in response to an input signal and applying the input signal to a second node in response to a reference signal; a bootstrapping unit applying the power voltage to the second node according to a voltage level of the first node; and an output unit applying the input signal to an output terminal in response to the reference signal and applying the power voltage to the output terminal according to the voltage level of the first node, wherein the bootstrapping unit includes a capacitor between the first and second nodes, and when the input signal is shifted from a first voltage level to a second voltage level, the bootstrapping unit raises the voltage level of the first node to a level higher than the power voltage.


Patent
Konkuk University and Samsung | Date: 2011-02-01

Example embodiment are directed to a reflective display device including a polymer-dispersed liquid crystal (PDLC) layer between a first substrate and a second substrate, and a mirror reflection plate on the first substrate.


Patent
Samsung and Konkuk University | Date: 2013-06-26

A digital Phase Locked Loop (PLL) in a wireless communication system is provided. The PLL includes a Digitally Controlled Oscillator (DCO), a divider, a Phase Frequency Detector (PFD), a Time to Digital Converter (TDC), a delay comparator, and a level scaler. The DCO generates a frequency signal depending on an input Digital Tuning Word (DTW). The divider divides the frequency signal at an integer ratio. The PFD generates a signal representing a phase difference between a divided frequency signal and a reference signal. The TDC measures a time interval of the phase difference using the signal representing the phase difference. The delay comparator calculates a time interval in the case where rising edges coincide from values measured by the TDC. The level scaler generates a DTW that operates the DCO using a digital code representing the time interval.


Patent
Samsung and Konkuk University | Date: 2016-03-08

Provided are pixel circuits using organic light emitting diodes (OLEDs) and a driving method thereof, and an organic light emitting display including the pixel circuits. The OLED is driven to emit light by a drive transistor generating a drive current compensated with respect to a threshold voltage difference and mobility deviation. The drive transistor may receive reference voltage and data signals in response to separate scan signals supplied to the pixel circuits via different scan lines. As a result, a threshold voltage compensation time, which may include the time during which a reference voltage is supplied to the drive transistor in response to a particular scan signal, may be set long enough regardless of a time during which the data signal is supplied to the pixel circuits located in respective rows of the organic light emitting display in response to a separate scan signal.


Patent
Konkuk University and Samsung | Date: 2011-04-19

A Time-to-Digital Converter (TDC) is provided. The TDC includes a first TDC unit for receiving a first input signal and a second input signal, delaying the first input signal on a specific time basis using each of first delay blocks, generating first phase-divided signals by performing first phase division on signals of input/output nodes for each of the first delay blocks on a predefined Phase-Interpolation (PI) delay time basis, and outputting the second input signal and a phase-divided signal closest to the second input signal, among the first phase-divided signals, a time amplifier for independently time-amplifying the second input signal and the phase-divided signal closest to the second input signal, and a second TDC unit for delaying a phase-divided signal closest to the time-amplified second input signal on a specific time basis using each of second delay blocks, and generating second phase-divided signals by performing second phase division on signals of input/output nodes for each of the second delay blocks on a predefined PI delay time basis.


Chung M.-Y.,Seoul National University | Oh D.-K.,Konkuk University | Lee K.W.,Seoul National University | Lee K.W.,University of Suwon
Journal of Agricultural and Food Chemistry | Year: 2012

Diabetes is an emerging health problem worldwide. The incidence of type 2 diabetes has dramatically increased and is expected to increase more rapidly in the future. Most patients with type 2 diabetes suffer from obesity and diabetes-related complications, including cardiovascular disease and hepatic steatosis. It has been proposed that simple sugar consumption is one of the major risk factors in the development of diabetes. Hence, the replacement of sugars with a low glycemic response would be an effective strategy to prevent type 2 diabetes. Accumulating evidence demonstrates that d-psicose, which has 70% the sweetness of sucrose and no calories, is a functional sugar exerting several health benefits preventing the development of diabetes. Although d-psicose presents in small amounts in natural products, a recent new technique using biocatalyst sources enables large-scale d-psicose production. More importantly, several clinical and animal studies demonstrated that d-psicose has hypoglycemic, hypolipidemic, and antioxidant activities, which make it an ideal candidate for preventing diabetes and related health concerns. This review will summarize the protective effects of d-psicose against type 2 diabetes and its complications, suggesting its potential benefits as a sucrose substitute. © 2011 American Chemical Society.


Choi J.K.,Konkuk University | Lym Y.L.,Konkuk University | Moon J.W.,Konkuk University | Shin H.J.,Konkuk University | Cho B.,Seoul National University
Archives of Ophthalmology | Year: 2011

Objective: To examine the association of diabetes mellitus and early age-related macular degeneration (AMD) in Korean adults 50 years and older. Methods: This study included 3008 participants aged 50 to 87 years. Early AMD was assessed from retinal photographs based on a modified Wisconsin AMD grading system. Diabetes mellitus was defined as a fasting glucose level of 126 mg/dL or greater or the use of antidiabetic medications. Logistic regression was used to examine the association between diabetes mellitus and early AMD. Results: There were 88 subjects with earlyAMDand 315 subjects with diabetes mellitus. After adjusting for age, sex, current smoking, obesity, and hypertension, significant association was found between diabetes mellitus and early AMD. Subjects with diabetes mellitus were more likely to have early AMD (odds ratio, 1.87; 95% confidence interval, 1.07-3.28) than were those without diabetes mellitus. Conclusion: There is a relationship between diabetes mellitus and early AMD in Korean adults 50 years and older. The underlying biological processes remain to be determined. ©2011 American Medical Association. All rights reserved.


Yoo H.J.,Konkuk University | Kim K.H.,Korean Intellectual Property Office | Yadav S.K.,Konkuk University | Cho J.W.,Konkuk University
Composites Science and Technology | Year: 2012

To generate poly(ethylene terephthalate) (PET) fibers with enhanced mechanical properties, we prepared melt-spun PET fibers that incorporated pristine, acid-treated, and functionalized multi-walled carbon nanotubes (MWNTs) with 2-phenylethyl alcohol and 4-phenyl-1-butanol. The incorporation of MWNTs into the melt-spun fibers resulted in increased crystallization of PET but lower breaking stress than that of pure PET fibers, even in those containing well-dispersed functionalized MWNTs. The breaking stress of drawn composite fibers was also lower than that of pure PET fibers prepared at the same draw ratio. However, the annealing of melt-spun fibers enhanced the mechanical properties and crystallization, and the annealing effect was more dominant for composite fibers with functionalized MWNTs. These findings indicate that the presence of well-dispersed MWNTs disturbs the crystallization and orientation of PET molecules in highly stressed fibers, which differs from MWNT-induced crystallization of PET molecules in relaxed fibers. © 2012 Elsevier Ltd.


Patent
Konkuk University, Electronics and Telecommunications Research Institute | Date: 2012-10-02

Disclosed is a DC voltage conversion circuit of a liquid crystal display apparatus, including: a main pumping circuit including a plurality of thin film transistors and configured to output voltage for driving a liquid crystal display apparatus when the plurality of thin film transistors are alternately turned on or off; and a switch control signal generator configured to control voltages applied to gates of the plurality of thin film transistors by inversion of a clock signal, in which each thin film transistor is turned on when positive gate-source voltage is applied thereto, and turned off when negative gate-source voltage is applied thereto.


Patent
Konkuk University, Electronics and Telecommunications Research Institute | Date: 2012-01-20

Disclosed are an inverter, a NAND gate, and a NOR gate. The inverter includes: a pull-up unit constituted by a second thin film transistor outputting a first power voltage to an output terminal according to a voltage applied to a gate; a pull-down unit constituted by a fifth thin film transistor outputting a ground voltage to the output terminal according to an input signal applied to a gate; and a pull-up driver applying a second power voltage or the ground voltage to the gate of the second thin film transistor according to the input signal.


Patent
Electronics, Telecommunications Research Institute and Konkuk University | Date: 2012-08-08

The present invention relates to a component identification method using an instance metadata identifier with a contents reference identifier (CRID) and a targeting method using the same. The present invention is a method for identifying components having identical contents and different bit expressions by assigning an identical CRID to each of the components, assigning different instance metadata identifiers to each of the components and using the instance metadata identifiers with the CRID. Also, the present invention is a method for identifying components having identical contents, identical bit expressions and different locations by assigning different instance metadata identifiers to each of the components and listing the instance metadata identifiers in a package metadata having corresponding condition of an intended targeting. Accordingly, the present invention provides effective targeting by automatically matching characteristics described in a package to a usage environment.


News Article | December 1, 2015
Site: www.nanotech-now.com

Home > News > Graphene-Coated Wearable 'E-Textile' Can Alert Wearer To Presence Of Dangerous Gases Abstract: Scientists at the Electronics and Telecommunications Research Institute in Konkuk University, Republic of Korea, have created a gas sensor that you can simply embroider onto any item of clothing. On exposure to high concentrations of nitrogen dioxide in the air, the electrical properties of this electronic textile, or e-textile, change, causing a light emitting diode to shine, alerting the wearer to the dangerously high levels of this dangerous gas in the air they are breathing in.


Kil H.,Korea University | Nam W.,Konkuk University
International Journal of Web and Grid Services | Year: 2013

The web service composition problem aims to find an optimal composition of web services to satisfy a given request by using their syntactic and/or semantic features when no single service satisfies it. In particular, the semantics of services helps a composition engine identify more correct, complete and optimal candidates as a solution. In this paper, we study the web service composition problem considering semantic aspects, i.e., exploiting the semantic relationship between parameters of web services. Given a set of web service descriptions, their semantic information and a requirement web service, we find the optimal composition that contains the shortest path of semantically well connected web services which satisfies the requirement. Our techniques are based on semantic matchmaking and three model checking techniques such as Boolean satisfiability solving, symbolic model checking, and abstraction and refinement technique. In the experiment, our proposal efficiently identifies optimal compositions of web services. © 2013 Inderscience Enterprises Ltd.


Kil H.,Korea University | Nam W.,Konkuk University
International Journal of Web and Grid Services | Year: 2013

The QoS-aware web service composition (WSC) problem aims at the fully automatic construction of a composite web service with the optimal accumulated QoS value. It is, however, intractable to solve the QoS-aware WSC problem for large scale instances since the problem corresponds to a global optimisation problem. That is, in the real world, traditional algorithms can require significant amount of time to finally find the optimal solution, and such an unexpected long delay is unfavourable to users. In this paper, we propose a novel anytime algorithm using dynamic beam widths for the QoSaware WSC problem. Our algorithm generates early sub-optimal solutions and keeps improving the quality of the solution along with the execution time, up to the optimal solution if a client allows enough time. We empirically validate that our algorithm can identify composite web services with high quality much earlier than an optimal algorithm and the beam stack search. Copyright © 2013 Inderscience Enterprises Ltd.


Yoon J.-W.,Korea University | Hong Y.J.,Konkuk University | Kang Y.C.,Konkuk University | Lee J.-H.,Korea University
RSC Advances | Year: 2014

SnO2 yolk-shell spheres uniformly loaded with Ag nanoparticles were prepared by a facile one-pot ultrasonic spray pyrolysis of the source solution and the H2S sensing characteristics were investigated. The Ag-loaded SnO2 yolk-shell spheres showed ultrahigh and reversible response (Ra/Rg - 1 = 613.9, where Ra is the resistance in air and Rg is the resistance in gas) to 5 ppm H 2S with negligible cross-responses (0.6-17.3) to eight other interference gases at 350 °C. In contrast, pure SnO2 spheres with dense inner structures and yolk-shell morphologies did not exhibit a high response/selectivity to H2S nor reversible H2S sensing. The highly sensitive, selective, and reversible H2S sensing characteristics were explained in terms of the gas-accessible yolk-shell morphology and uniform loading of catalytic Ag nanoparticles. Namely, the gas-accessible yolk-shell morphology facilitated the rapid and effective diffusion of the analyte/oxygen gases and the uniform loading of Ag nanoparticles promoted the H2S sensing reaction. This journal is © the Partner Organisations 2014.


Kang Y.J.,Korea University | Chung H.,Konkuk University | Han C.-H.,Korea Institute of Energy Research | Kim W.,Korea University
Nanotechnology | Year: 2012

All-solid-state flexible supercapacitors were fabricated using carbon nanotubes (CNTs), regular office papers, and ionic-liquid-based gel electrolytes. Flexible electrodes were made by coating CNTs on office papers by a drop-dry method. The gel electrolyte was prepared by mixing fumed silica nanopowders with ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf 2]). This supercapacitor showed high power and energy performance as a solid-state flexible supercapacitor. The specific capacitance of the CNT electrodes was 135Fg 1 at a current density of 2Ag 1, when considering the mass of active materials only. The maximum power and energy density of the supercapacitors were 164kWkg 1 and 41Whkg 1, respectively. Interestingly, the solid-state supercapacitor with the gel electrolyte showed comparable performance to the supercapacitors with ionic-liquid electrolyte. Moreover, the supercapacitor showed excellent stability and flexibility. The CNT/paper-and gel-based supercapacitors may hold great potential for low-cost and high-performance flexible energy storage applications. © 2012 IOP Publishing Ltd.


Park K.Y.,Konkuk University | Lee J.W.,Korea University | Song K.G.,Korea Institute of Science and Technology | Ahn K.H.,Korea Institute of Science and Technology
Bioresource Technology | Year: 2011

Potential use of the municipal sludge ozonolysate as a carbon source was examined for phosphorus removal from low strength wastewater in a modified intermittently decanted extended aeration (IDEA) process. At ozone dosage of 0.2g O3/g solids, readily biodegradable COD accounted for about 36% of COD from sludge ozonolysate. The denitrification potential of ozonolysate as a carbon source was comparable to that of acetate. Although, the first order constant for phosphorus release with the ozonolysate was half that of acetate, it was much higher than that of wastewater. Continuous operation of the modified IDEA process showed that the removals of nitrogen and phosphorus were simultaneously enhanced by addition of the ozonolysate. Phosphorus release was significantly induced after complete denitrification indicating that phosphorus release was strongly depended on nitrate concentration. Effectiveness of the ozonolysate as a carbon source for EBPR was also confirmed in a track study of the modified IDEA. © 2010 Elsevier Ltd.


Choi S.H.,Korea University | Choi S.H.,Konkuk University | Lee J.-K.,Konkuk University | Kang Y.C.,Korea University
Nanoscale | Year: 2014

A new concept for discovering multicomponent nanostructured materials with good electrochemical properties is proposed. Yolk-shell-structured transition metal oxide powders with seven to ten components and simple crystal structures are prepared by continuous spray pyrolysis. The multicomponent yolk-shell powders with complex compositions show excellent Li+ storage properties for lithium ion batteries. © 2014 the Partner Organisations.


Ko Y.N.,Korea University | Choi S.H.,Konkuk University | Park S.B.,Korea Advanced Institute of Science and Technology | Kang Y.C.,Korea University
Nanoscale | Year: 2014

Yolk-shell-structured MoSe2 microspheres were prepared via a simple selenization process of MoO3 microspheres. The yolk-shell-structured MoSe2 and MoO3 microspheres delivered initial discharge capacities of 527 and 465 mA h g-1 in the voltage range of 0.001-3 V vs. Na/Na+ at a current density of 0.2 A g-1, respectively, and their discharge capacities after 50 cycles were 433 and 141 mA h g-1, respectively. The yolk-shell-structured MoSe2 microspheres also exhibited outstanding high rate capabilities. The hierarchical yolk-shell structure comprised of wrinkled nanosheets facilitated fast Na-ion and electron kinetics, and buffered the large volume changes encountered during cycling. © the Partner Organisations 2014.


Yoon J.,Korea University | Baik H.,Korea Basic Science Institute | Lee S.,Konkuk University | Kwon S.J.,Konkuk University | Lee K.,Korea University
Nanoscale | Year: 2014

Ultralong coaxial Au@Pt nanocables prepared by one-pot synthesis exhibit excellent electrocatalytic activity due to structural features of (1) numerous twinning boundaries and (2) lattice mismatch between the core and the shell. © The Royal Society of Chemistry 2014.


Kim B.,Korea University | Chung H.,Konkuk University | Kim W.,Korea University
Nanotechnology | Year: 2012

We demonstrate the high performance of supercapacitors fabricated with vertically aligned carbon nanotubes and nonaqueous electrolytes such as ionic liquids and conventional organic electrolytes. Specific capacitance, maximum power and energy density of the supercapacitor measured in ionic liquid were 75Fg 1, 987kWkg 1 and 27Whkg 1, respectively. The high power performance was consistently indicated by a fast relaxation time constant of 0.2s. In addition, electrochemical oxidation of the carbon nanotubes improved the specific capacitance (158Fg 1) and energy density (53Whkg 1). Both high power and energy density could be attributed to the fast ion transport realized by the alignment of carbon nanotubes and the wide operational voltage defined by the ionic liquid. The demonstrated carbon-nanotube-and nonaqueous-electrolyte-based supercapacitors show great potential for the development of high-performance energy storage devices. © 2012 IOP Publishing Ltd.


Kang H.,TU Chemnitz | Park J.,Konkuk University | Shin K.,Konkuk University
Robotics and Computer-Integrated Manufacturing | Year: 2014

Roll-to-roll (R2R) slot-die coating systems are mostly devoted to the mass manufacture of printed electronics. This study examined the correlation among the operating conditions, thickness, and width of the patterned strip fabricated by the R2R slot-die system. A full factorial experiment was conducted to screen for effective parameters. The velocity of a moving substrate was found to be the most dominant parameter affecting the thickness and width of the patterned strips. The flow ratio of the supply to the slot-die, and gap between substrate and slot-die did not affect the width of the strip, but affected the thickness; therefore, the flow ratio and gap can be employed for the independent patterning of thickness against width. In addition, it was proposed to determine the R2R process conditions, such as gap, velocity, and flow ratio for the desired thickness and width of the patterned strips. © 2013 Elsevier Ltd.


Noh K.T.,Korea University | Park Y.-M.,Pusan National University | Cho S.-G.,Konkuk University | Choi E.-J.,Korea University
Experimental Cell Research | Year: 2011

Glycogen synthase kinase-3β (GSK-3β), a multifunctional kinase, is a regulator of lipopolysaccharide (LPS)-mediated septic shock. Apoptosis signal-regulating kinase 1 (ASK1) is also required for LPS-induced activation of p38, which is a crucial determinant for the production of pro-inflammatory cytokines via Toll-like receptor 4 (TLR4) in endotoxemia. Here, we show that attenuation of endotoxemia induced by GSK-3 inhibition is caused by the ASK1 reduction-mediated inhibition of p38, a representative downstream kinase of ASK1. LPS-stimulated activation of p38 was blocked by the reduction of ASK1 via the knockdown of GSK-3β In addition, compared with L929 control cells, ASK1 protein was reduced in L929 cells stably expressing Wnt-3a and in which β-catenin was active, due to the inhibition of GSK-3β activity. GSK-3β inhibition-mediated ASK1 reduction was also confirmed by reduced ASK1 in GSK-3β-deficient mouse embryo fibroblasts (MEFs) and MCF7 GSK-3β siRNA cells. Furthermore, ASK1 protein stability was also attenuated in MCF7 GSK-3β siRNA cells compared with GFP control cells. Consistent with stability data, a much stronger ubiquitination of ASK1 was observed in cells in which GSK-3β was knocked down. These findings suggest that GSK-3β crosstalks with p38 kinase via the regulation of ASK1 protein stability in endotoxemia. © 2011 Elsevier Inc.


Shin J.E.,Konkuk University | Kim C.-H.,Konkuk University | Park H.J.,University of Ulsan
Acta Oto-Laryngologica | Year: 2013

Conclusion: Vestibular abnormality was found in 84% of patients with Meniere's disease (MD) and 66% of those with migrainous vertigo (MV), even in the interictal period. Although MV does not have proven pathology like endolymphatic hydrops of MD, MV had high vestibular abnormality, suggesting that comorbid vestibular abnormality can be a cause of vertigo and needs to be pursued. Objectives: MD and MV are common disorders causing recurrent vertigo. We determined the vestibular abnormality rates using vestibular tests with objective measurements. Methods: Results of caloric, head-shaking nystagmus (HSN), and vibration-induced nystagmus (VIN) tests were analyzed in 45 patients with MD and 76 with MV. Results: The abnormal rates in MD were significantly higher than those in MV. Of 45 MD patients, 21 (47%), 32 (71%), and 24 (53%) exhibited abnormal caloric, HSN, and VIN results, respectively. Fourteen (31%) MD patients had migraine associated with vertigo, but the association was not accompanied by high rates of abnormal results in the tests. Of 76 MV patients, 19 (25%), 38 (50%), and 24 (32%) exhibited abnormal caloric, HSN, and VIN results, respectively. Overall, 84% of patients with MD and 66% with MV exhibited abnormal results on at least one test. Abnormal rates were highest in HSN, followed by VIN and the caloric test. © 2013 Informa Healthcare.


Kim S.-J.,Korea University | Hwang I.-S.,Korea University | Na C.W.,Korea University | Kim I.-D.,Korea Advanced Institute of Science and Technology | And 2 more authors.
Journal of Materials Chemistry | Year: 2011

Rh-loaded In2O3 hollow spheres with diameters of ∼2 μm were prepared by a one-pot hydrothermal reaction of aqueous solution containing indium nitrate, rhodium chloride, and glucose and subsequent heat treatment at 500 °C for 2 h. The response to 100 ppm C 2H5OH (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) of 1.67 at% Rh-loaded In2O3 hollow spheres was 4748, which was ∼180 times higher than that of pure In2O3 hollow spheres. Rh loading decreased the temperature for maximum gas response from 475 °C to 371 °C, which also enhanced the selectivity to C2H5OH 15.1-24.7 times and recovery speed. The ultrahigh sensitivity and selectivity to C2H5OH, the lower sensing temperature, and the reduced recovery time were attributed to electronic interactions between Rh and In 2O3 and the promotion of catalytic dissociation of C 2H5OH into reactive gases. © 2011 The Royal Society of Chemistry.


Jin B.,University of North Carolina at Greensboro | Park J.Y.,Konkuk University | Kim H.-S.,University of Delaware
Behaviour and Information Technology | Year: 2010

A growing number of firms are using online communities (OCs) as integral parts of their strategies because of the value an OC provides to a firm. This study maintains the commitment to an OC to be critical in developing a sustainable OC and examines how members' commitment to an OC develops in the context of OCs hosted by firms and freely available to anyone. Built on the social exchange theory, the proposed model posits that two aspects of OC attributes (Sociability and Usability) facilitate members' participation in an OC, as well as bring social and functional benefits to participants. In return for the benefits gained from OC participation, participants reciprocate with affective and calculative commitment to the OC. Data were collected via online survey from OC participants who were 18 years old or above and resided in South Korea. An analysis of 595 cases supported the proposed model. Results indicated that the members' perceived social benefits from active OC participation led to an affective commitment to the OC, while members' perceived functional benefits led to a calculative commitment to the OC. Theoretical and managerial implications were suggested based on the findings. © 2010 Taylor & Francis.


Kim J.-Y.,University of Texas at Austin | Lee W.H.,University of Texas at Austin | Lee W.H.,Konkuk University | Suk J.W.,University of Texas at Austin | And 7 more authors.
Advanced Materials | Year: 2013

Phenyl isocyanate-functionalized and hydrazine-reduced reduced graphene oxide (rG-O) is treated to produce chlorinated rG-O (Cl-rG-O) platelets. The dielectric constant of the composite film containing Cl-rG-O shows a 5.5-fold increase over that of composites of untreated rG-O and this cyanoethyl-based polymer, a consequence of the combination of polar and polarizable C-Cl bonds and the increased interfacial polarization. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Nath N.C.D.,Konkuk University | Lee H.J.,Konkuk University | Choi W.-Y.,Korea University | Lee J.-J.,Konkuk University
Electrochimica Acta | Year: 2013

The net enhancement of open-circuit voltage (Voc) of dye-sensitized solar cells (DSSCs) was achievedwith the novel electrolyte composed of interhalogen based binary-redox couples without regard to thechoice of sensitizers. The interhalogen ion, I2Br-, was formed in the conventional iodine-based elec-trolyte by both chemically and electrochemically and it was found to produce an extra redox pair, (I -,Br-)/I2Br-, with new energy state at a more positive potential than that of I-/I3 -. The Fermi level of theelectrolyte shifted positively by the weighted-average of the two redox systems. It induced the increase of V oc up to 30, 60, and 50 mV for cis-diisothiocyanato-bis(2,2′- bipyridyl-4,4′-dicarboxylato) ruthenium(II)bis(tetrabutylammonium) (N719), cis-dicyano-bis(2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium(II)(Ruthenizer 505 or Ru505), and 2′,4′,5′,7′- tetrabromofluorescein (eosin Y) dyes, respectively, withoutaffecting the short circuit current much. It corresponded to the enhancement of the overall power con-version efficiency (η) up to 8, 14, and 13%, respectively. Moreover, the degree of enhancement of Voc was controllable by varying [I 2Br-] since the higher the contribution of [I 2Br-] the more positive shift in theenergy level of the binary redox couples. © 2013 Elsevier Ltd. All rights reserved.


Paul S.,Konkuk University | Jeon W.K.,Korea Institute of Oriental Medicine | Bizon J.L.,Florida College | Han J.-S.,Konkuk University
Frontiers in Aging Neuroscience | Year: 2015

A substantial number of studies on basal forebrain cholinergic neurons (BFCN) have provided compelling evidence for their role in the etiology of stress, cognitive aging, Alzheimer's disease (AD), and other neurodegenerative diseases. BFCN project to a broad range of cortical sites and limbic structures, including the hippocampus, and are involved in stress and cognition. In particular, the hippocampus, the primary target tissue of the glucocorticoid stress hormones, is associated with cognitive function in tandem with hypothalamic-pituitary-adrenal (HPA) axis modulation. The present review summarizes glucocorticoid and HPA axis research to date in an effort to establish the manner in which stress affects the release of acetylcholine, glucocorticoids, and their receptor in the context of cognitive processes. We attempt to provide the molecular interactive link between the glucocorticoids and cholinergic system that contributes to BFCN degeneration in stress-induced acceleration of cognitive decline in aging and AD. We also discuss the importance of animal models in facilitating such studies for pharmacological use, which could help decipher disease states and propose leads for pharmacological intervention. © 2015 Paul, Jeon, Bizon and Han.


Kwon S.J.,Konkuk University | Bard A.J.,University of Texas at Austin
Journal of the American Chemical Society | Year: 2012

This study demonstrates a highly sensitive sensing scheme for the detection of low concentrations of DNA, in principle down to the single biomolecule level. The previously developed technique of electrochemical current amplification for detection of single nanoparticle (NP) collisions at an ultramicroelectrode (UME) has been employed to determine DNA. The Pt NP/Au UME/hydrazine oxidation reaction was employed, and individual NP collision events were monitored. The Pt NP was modified with a 20-base oligonucleotide with a C6 spacer thiol (detection probe), and the Au UME was modified with a 16-base oligonucleotide with a C6 spacer thiol (capture probe). The presence of a target oligonucleotide (31 base) that hybridized with both capture and detection probes brought a Pt NP on the electrode surface, where the resulting electrochemical oxidation of hydrazine resulted in a current response. © 2012 American Chemical Society.


Yu M.S.,Konkuk University | Jang Y.J.,University of Ulsan
Aesthetic Surgery Journal | Year: 2014

Background: Preoperative computer simulation (PCS) is a tool for demonstrating potential rhinoplasty results to patients and determining the patient's preferred external nasal appearance. Objectives: The authors evaluated the effectiveness of PCS in Asian rhinoplasty patients. Methods: The records of 224 patients who underwent rhinoplasty were reviewed. Sixty-eight (30.4%) of these patients had received PCS. To evaluate the accuracy of PCS in predicting postoperative results, postoperative photographs and PCS images were graded on a 4-point scale by a panel of 3 otolaryngologists. Postoperative patient satisfaction was compared between the PCS and non-PCS groups. Aesthetic parameters were assessed in the PCS images to determine the patient's preferred external nasal appearance. Results: The mean overall accuracy of PCS was 86.0% according to the otolaryngologist panel's ratings: 41.2% of the surgical results were rated as identical, 44.1% as similar, 13.2% as approximate, and 1.5% as poor. There were no significant differences between the PCS and non-PCS groups in terms of patient satisfaction or revision rates (P > .05). The most favored nasal appearances were straight dorsum (63.2%), straight columella (50.0%), and convergent alar axis (64.7%). The mean (± standard deviation) preferred nasofrontal and nasolabial angles were 137.5° ± 6.9° and 97.3° ± 8.6°, respectively. Conclusions: Preoperative computer simulation is an accurate tool for assessing preferred external nasal appearance and can be a reliable predictor of postoperative rhinoplasty results in Asian patients. © 2014 The American Society for Aesthetic Plastic Surgery, Inc.


Han S.,Konkuk University | Kim K.,University of Kentucky | Thakkar N.,University of Kentucky | Kim D.,Konkuk University | Lee W.,University of Kentucky
Biochemical Pharmacology | Year: 2013

Organic anion transporting polypeptide 1B3 (OATP1B3) was initially considered to be a liver-specific transporter, mediating the uptake of a variety of endogenous and xenobiotic substances. Over the past decade, several investigations reported that OATP1B3 is also expressed across multiple types of cancers. Only recently, our laboratory and others demonstrated the identity of cancer-specific OATP1B3 variants (csOATP1B3) arising from the use of an alternative transcription initiation site, different from the wildtype (WT) OATP1B3 expressed in the normal liver. However, the mechanisms regulating the expression of csOATP1B3 remained unknown. In our current study, we investigated the role of hypoxia and the involvement of hypoxia inducible factor-1α (HIF-1α) in regulating the transcription of csOATP1B3. Our RT-PCR and immunoblotting results indicated that csOATP1B3, but not WT OATP1B3, can be induced in response to ambient or chemical hypoxia (upon exposure to 1% O 2 or cobalt chloride). Reporter assays with deletion and mutated constructs of the csOATP1B3 promoter revealed a functional hypoxia response element (HRE) located in the proximal upstream region. Constructs harboring the HRE displayed the upregulated reporter gene expression in response to hypoxia, but not when mutated. Electrophoretic mobility shift assays using a biotin-labeled csOATP1B3 promoter HRE probe indicated the binding of HIF-1a, which was blocked by an excess of unlabeled csOATP1B3 probe. Furthermore, siRNA-based knockdown of HIF-1a caused a substantial decrease in the expression level of csOATP1B3. Taken together, these findings demonstrate that the transcription of csOATP1B3 is actively engaged during hypoxia, through a commonly utilized pathway involving HIF-1α. © 2013 Elsevier Inc. All rights reserved.


Park G.D.,Korea University | Lee J.-H.,Korea University | Lee J.-K.,Konkuk University | Kang Y.C.,Korea University
Nano Research | Year: 2014

In this study, for the first time, polymeric precursors have been used in the preparation of yolk-shell powders using a large-scale spray drying process. An esterification reaction between the carboxyl group of citric acid and the hydroxyl group of ethylene glycol inside the droplet produced organic polymers during the drying process of the droplet. During the spray drying process, the polymeric precursors enabled the formation of multi-shell cobalt oxide yolk-shell powders with superior electrochemical properties. The maximum number of shells of the particles in the yolk-shell powders post-treated at 300, 400, and 500 °C were six, five, and four, respectively. The initial discharge capacities of the cobalt oxide yolk-shell powders post-treated at 300, 400, and 500 °C were 1,188, 1,331, and 1,110 mAh·g−1, and their initial charge capacities were 868, 1,005, and 798 mAh·g−1, respectively. The discharge capacities of the powders post-treated at 300, 400, and 500 °C after 100 cycles were 815, 958, and 670 mAh·g−1, respectively, and their corresponding capacity retentions measured after the first cycles were 92%, 93%, and 82%, respectively. The pure phase Co3O4 yolk-shell powders post-treated at 400 °C had low charge transfer resistance and high lithium-ion diffusion rate.[Figure not available: see fulltext.]. © 2014, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.


Kang H.,TU Chemnitz | Lee C.,FLEXIBLE DISPLAY | Shin K.,Konkuk University
Control Engineering Practice | Year: 2013

For mass manufacturing of printed electronics using roll-to-roll printing, high-resolution register control among multi-layers is required. A mathematical model of a machine directional (MD) register was derived, where the compensation method was proposed to cancel out the upstream disturbance of the MD register. The proposed MD register model and compensator could be used to improve the performance of the MD register controller in multi-layer roll-to-roll printed electronics. The proposed compensator was experimentally verified at various operating conditions. The results show that the proposed compensator improves the control performance of the MD register in overcoming upstream disturbances. © 2013.


Choi S.H.,Konkuk University | Lee J.-H.,Korea University | Kang Y.C.,Konkuk University
Nanoscale | Year: 2013

Core-shell structured NiO@TiO2 nanopowders for application as anode materials for lithium ion batteries are prepared by one-pot flame spray pyrolysis from aqueous spray solution containing Ni and Ti components. A new formation mechanism of the core-shell structured nanopowders in the flame spray pyrolysis is proposed. Composite nanopowders are first formed by surface growth and coagulation from NiO and TiO2 vapors. A small amount of TiO 2 in composite powders disturbs the crystallization of TiO 2. Therefore, the TiO2 component moves out to the surface of the powders forming an amorphous shell during the formation of single crystalline NiO. The initial discharge and charge capacities of the NiO@TiO 2 nanopowders at a current density of 300 mA g-1 are 1302 and 937 mA h g-1, respectively. The discharge capacities of the pure NiO and NiO@TiO2 nanopowders after 80 cycles are 542 and 970 mA h g-1, respectively. The capacity retentions of the pure NiO and NiO@TiO2 nanopowders after 80 cycles measured after the first cycles are 75 and 108%, respectively. © 2013 The Royal Society of Chemistry.


Lee S.M.,Konkuk University | Choi S.H.,Konkuk University | Kang Y.C.,Korea University
Chemistry - A European Journal | Year: 2014

Hierarchically structured tin oxide/reduced graphene oxide (RGO)/carbon composite powders are prepared through a one-pot spray pyrolysis process. SnO nanoflakes of several hundred nanometers in diameter and a few nanometers in thickness are uniformly distributed over the micrometer-sized spherical powder particles. The initial discharge and charge capacities of the tin oxide/RGO/carbon composite powders at a current density of 1000 mAg-1 are 1543 and 1060 mAhg-1, respectively. The discharge capacity of the tin oxide/RGO/carbon composite powders after 175 cycles is 844 mAhg-1, and the capacity retention measured from the second cycle is 80 %. The transformation during cycling of SnO nanoflakes, uniformly dispersed in the tin oxide/RGO/carbon composite powder, into ultrafine nanocrystals results in hollow nanovoids that act as buffers for the large volume changes that occur during cycling, thereby improving the cycling and rate performances of the tin oxide/RGO/carbon composite powders. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.