Seoul, South Korea
Seoul, South Korea

Korea University is a private research university located in Seoul, South Korea. It was established in 1905, making it one of the oldest institutions of higher education in South Korea.The student body consists of over 20,000 undergraduate students and over 10,000 graduate students. The university’s academic breadth is extensive with its 81 departments in 19 colleges and divisions, and 18 graduate schools and it has over 1,500 full-time faculty members with over 95% of them holding Ph.D. or equivalent qualification in their field. The Korea University Alumni Association consists of more than 280,000 university graduates.Korea University is a research institution consisting of sixteen undergraduate colleges and twenty graduate divisions.The university is notable in South Korean history for being the first educational institution to offer academic programs in various disciplines, such as law, economics, and journalism. Korea University is particularly well known for its College of Law, which is widely considered to be one of the most prestigious undergraduate law programs in South Korea. Korea University also has auxiliary educational facilities such as the Institute of Foreign Language Studies, the Institute for Continuing Education, the Institute of International Education, and the Center for Teaching and Learning. There are 115 research institutes, including the Battelle@KU Laboratory, the Ilmin International Relations Institute, and the Center for Information Security Technologies. Wikipedia.

Time filter

Source Type

Ahn C.K.,Korea University
International Journal of Control | Year: 2014

In this paper, we use an induced l∞ approach to create a new filter with a finite impulse response (FIR) structure for state-space models with external disturbances. This filter is called an induced l ∞ FIR filter (ILIFF). The proposed ILIFFs gain matrix can be determined by solving a linear matrix inequality problem for a fixed positive scalar variable. An illustrative example is given to demonstrate the effectiveness of the ILIFF. © 2013 © 2013 Taylor & Francis.

Kim H.-C.,Korea University | Minamitsuji M.,Sogang University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We discuss the primordial spectrum of a massless and minimally coupled scalar field, produced during the initial anisotropic epoch before the onset of inflation. We consider two models of the anisotropic cosmology, the (planar) Kasner-de Sitter solution (Bianchi I) and the Taub-NUT-de Sitter solution (Bianchi IX), where the 3-space geometry is initially anisotropic, followed by the de Sitter phase due to the presence of a positive cosmological constant. We discuss the behavior of a quantized, massless and minimally coupled scalar field in the anisotropic stage. This scalar field is not the inflaton and hence does not contribute to the background dynamics. We focus on the quantization procedure and evolution in the preinflationary anisotropic background. Also, in this paper for simplicity the metric perturbations are not taken into account. The initial condition is set by the requirement that the scalar field is initially in an adiabatic state. Usually, in a quantum harmonic oscillator system, an adiabatic process implies the one where the potential changes slowly enough compared to its size, and the time evolution can be obtained from the zeroth order WKB approximation. In our case, such a vacuum state exists only for limited solutions of the anisotropic universe, whose spacetime structure is regular in the initial times. In this paper, we call our adiabatic vacuum state the anisotropic vacuum. In the Kasner-de Sitter model, for one branch of planar solutions there is an anisotropic vacuum unless k30, where k3 is the comoving momentum along the third direction, while in the other branch there is no anisotropic vacuum state. In the first branch, for the moderate modes, k3∼k, where k is the total comoving momentum, the scalar power spectrum has an oscillatory behavior and its direction dependence is suppressed. For the planar modes, k3k, in contrast, the direction dependence becomes more important, because of the amplification of the scalar amplitude during this interval of the violation of WKB approximation in the initial anisotropic stage. The qualitative behaviors in the Taub-NUT-de Sitter models are very similar to the case of the first branch of the planar Kasner-de Sitter model. © 2010 The American Physical Society.

Jung S.-W.,Advanced Media | Ko S.-J.,Korea University
IEEE Transactions on Image Processing | Year: 2012

In this paper, we present a novel depth sensation enhancement algorithm considering the behavior of human visual system toward stereoscopic image displays. On the basis of the recent studies on the just noticeable depth difference (JNDD), which represents a threshold at which a human can perceive the depth difference between objects, we modify the depth image such that neighboring objects in the depth image can have a depth value difference of at least the JNDD. This modification is modeled via an energy minimization framework using three energy terms defined as depth data preservation, depth order preservation, and depth difference expansion. The depth data term enforces minimal changes in the depth image with an additional weighting function that controls the direction of depth changes. The depth order term restricts the inversion of the local and global depth orders among objects, and the JNDD term leads to an increase in the depth differences between segments. Throughout subjective quality evaluation on a stereoscopic image display, it is demonstrated that the human depth sensation is effectively improved by the proposed algorithm. © 1992-2012 IEEE.

Lee K.-W.,Korea University | Pickett W.E.,University of California at Davis
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Using first-principles calculations, we investigate the electronic and magnetic properties of the trigonally distorted (R3̄c) perovskite-derived NiCrO3. Within the local spin-density approximation (LSDA), our calculations show that this system is an exactly compensated half-metal (CHM). The local spin moments of Cr 2.04, and antialigned Ni -1.41 and three oxygens -0.63 (in the units of μB), indicate high spin S=32 Cr3 + and S=32 (NiO3)3- units. Considering reasonable values of the on-site Coulomb repulsion U on both Ni and Cr ions with LDA+U approach, this system becomes an insulator (as reported by Chamberland and Cloud) having a narrow gap in the spin-up channel, whereas the other channel has a large gap of ~3 eV. Although inclusion of U seemingly leads to the transition Ni2+→high spin S=32 Ni3+, consistent with the experimentally observed effective moment, the zero net moment remains unchanged due to either reduction of oxygen local moments or enhancement of Cr local moment. Compression of volume by 10% leads to CHM even when correlation effects are included. These results suggest the possibility of a CHM state in NiCrO3 and provide another route to search for CHM, which is a property sought by many. © 2011 American Physical Society.

Georgescu I.M.,RIKEN | Ashhab S.,RIKEN | Ashhab S.,Qatar Environment and Energy Research Institute | Nori F.,RIKEN | And 2 more authors.
Reviews of Modern Physics | Year: 2014

Simulating quantum mechanics is known to be a difficult computational problem, especially when dealing with large systems. However, this difficulty may be overcome by using some controllable quantum system to study another less controllable or accessible quantum system, i.e., quantum simulation. Quantum simulation promises to have applications in the study of many problems in, e.g., condensed-matter physics, high-energy physics, atomic physics, quantum chemistry, and cosmology. Quantum simulation could be implemented using quantum computers, but also with simpler, analog devices that would require less control, and therefore, would be easier to construct. A number of quantum systems such as neutral atoms, ions, polar molecules, electrons in semiconductors, superconducting circuits, nuclear spins, and photons have been proposed as quantum simulators. This review outlines the main theoretical and experimental aspects of quantum simulation and emphasizes some of the challenges and promises of this fast-growing field. © 2014 American Physical Society.

Korea University | Date: 2012-12-31

The present invention provides a method for planning a path for an autonomous walking humanoid robot that takes an autonomous walking step using environment map information, the method comprising: an initialization step of initializing path input information of the autonomous walking humanoid robot using origin information, destination information, and the environment map information; an input information conversion step of forming a virtual robot including information on the virtual robot obtained by considering the radius and the radius of gyration of the autonomous walking humanoid robot based on the initialized path input information; a path generation step of generating a path of the virtual robot using the virtual robot information, the origin information S, the destination information G, and the environment map information; and an output information conversion step of converting the path of the autonomous walking humanoid robot based on the virtual robot path generated in the path generation step.

Samsung, Sogang University and Korea University | Date: 2015-12-08

A block copolymer is provided. The block copolymer according to an exemplary embodiment includes a first block represented by Chemical Formula 1 and a second block represented by Chemical Formula 2: wherein COM1 and COM2 are independently selected from a polystyrene moiety, polymethylmethacrylate moiety, polyethylene oxide moiety, polyvinylpyridine moiety, polydimethylsiloxane moiety, polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 is hydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenyl group, a is 1 to 50, R2 is hydrogen or an alkyl group with 1 to 10 carbon atoms, and b is 1 to 50.

Sogang University and Korea University | Date: 2012-11-16

A user opinion extraction method that includes: searching for social network groups that respectively have made one or more connections to a site having a domain that relates to software to be developed using a search module; analyzing structures of social networks for the retrieved social network groups using an analysis module; selecting a social network group from which user opinions are to be extracted based on a result of the analysis and collecting user opinions from SNS sentences that are mutually transmitted and received between a plurality of nodes within the selected social network group using a collection module; calculating degrees of influences of the collected user opinions on the social network group using a calculation module; and extracting at least one user opinion from among the collected user opinions in order of a higher degree of the influence on the social network group using an extraction module.

Samsung, Sogang University and Korea University | Date: 2013-11-21

A block copolymer is provided. The block copolymer according to an exemplary embodiment includes a first block represented by Chemical Formula 1 and a second block represented by Chemical Formula 2: wherein COM1 and COM2 are independently selected from a polystyrene moiety, polymethylmethacrylate moiety, polyethylene oxide moiety, polyvinylpyridine moiety, polydimethylsiloxane moiety, polyferrocenyldimethylsilane moiety, and polyisoprene moiety, R1 is hydrogen or an alkyl group with 1 to 10 carbon atoms, Ph is a phenyl group, a is 1 to 50, R2 is hydrogen or an alkyl group with 1 to 10 carbon atoms, and b is 1 to 50.

Jung S.-W.,Advanced Media | Ko S.-J.,Korea University
IEEE Signal Processing Letters | Year: 2012

Color stereopsis is a phenomenon in the human visual system (HVS) in which a long wavelength color is perceived as being located closer than a short wavelength color. Although many psychophysical studies on color stereopsis have been carried out, its practical application is not fully investigated. In this letter, we propose a new image enhancement algorithm using color stereopsis between red and blue colors. First, the relationship of red and blue colors to the depth perception is analyzed. Then, a simple but practical image enhancement algorithm is presented based on the analysis result. The experimental results demonstrate the effectiveness of the proposed algorithm. © 1994-2012 IEEE.

Brummitt C.D.,University of California at Davis | Lee K.-M.,Korea University | Goh K.-I.,Korea University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

Elements of networks interact in many ways, so modeling them with graphs requires multiple types of edges (or network layers). Here we show that such multiplex networks are generically more vulnerable to global cascades than simplex networks. We generalize the threshold cascade model to multiplex networks, in which a node activates if a sufficiently large fraction of neighbors in any layer are active. We show that both combining layers (i.e., realizing other interactions play a role) and splitting a network into layers (i.e., recognizing distinct kinds of interactions) facilitate cascades. Notably, layers unsusceptible to global cascades can cooperatively achieve them if coupled. On one hand, this suggests fundamental limitations on predicting cascades without full knowledge of a system's multiplexity; on the other hand, it offers feasible means to control cascades by introducing or removing sparse layers in an existing network. © 2012 American Physical Society.

Choi K.-H.,Korea University | Til W.,King's College London | Kurtz M.M.,Wesleyan University
British Journal of Psychiatry | Year: 2013

Background: A growing number of studies have investigated the efficacy of novel, adjunctive pharmacotherapies for treatment of cognitive deficits in schizophrenia with conflicting results. Aims: To investigate the comparative efficacy of these agents on cognition and symptoms in schizophrenia, and to identify promising cognitive domains and candidate medications that can be incorporated in treatment trials combined with cognitive remediation to maximise treatment effects. Method: A total of 26 double-blind, placebo-controlled studies investigating medications targeted at cholinergic, glutamatergic or serotonergic receptor classes and with participants with schizophrenia or schizoaffective disorder were identified. Results: Medications targeted at the cholinergic receptor class produced marginal improvements in verbal learning and memory (d = 0.23, P = 0.06), and donepezil, a specific type of cholinergic agonist, produced a moderate effect (d = 0.58) on spatial learning and memory. Cholinergic and glutamatergic agents produced moderate effect-size improvements on negative symptoms (d = 0.54 and d = 0.62 respectively), and small effect-size improvements on general symptoms (d = 0.46 and d = 0.41 respectively). Serotonergic agents produced small effect-size improvements in positive symptoms (d = 0.33). Conclusions: Cholinergic medications produced marginal improvement in verbal learning and memory and moderate improvements on spatial learning and memory, although there was no evidence to support the use of glutamatergic or serotonergic medications as a stand-alone treatment for improving cognitive function. Cholinergic and glutamatergic agents improved negative and general symptoms, whereas serotenergic medications improved positive symptoms.

Ko Y.,Kookmin University | Kim Y.,Korea University | Baek H.,Korea University | Cho J.,Korea University
ACS Nano | Year: 2011

Electrochemical properties of redox proteins, which can cause the reversible changes in the resistance according to their redox reactions in solution, are of the fundamental and practical importance in bioelectrochemical applications. These redox properties often depend on the chemical activity of transition metal ions as cofactors within the active sites of proteins. Here, we demonstrate for the first time that the reversible resistance changes in dried protein films based on ferritin nanoparticles can be caused by the externally applied voltage as a result of charge trap/release of Fe III/Fe II redox couples. We also show that one ferritin nanoparticle of about 12 nm size can be operated as a nanoscale-memory device, and furthermore the layer-by-layer assembled protein multilayer devices can be extended to bioinspired electronics with adjustable memory performance via molecular level manipulation. © 2011 American Chemical Society.

Choi H.,University of Notre Dame | Nicolaescu R.,University of Notre Dame | Paek S.,Korea University | Ko J.,Korea University | Kamat P.V.,University of Notre Dame
ACS Nano | Year: 2011

The photoresponse of quantum dot solar cells (QDSCs) has been successfully extended to the near-IR (NIR) region by sensitizing nanostructured TiO 2-CdS films with a squaraine dye (JK-216). CdS nanoparticles anchored on mesoscopic TiO2 films obtained by successive ionic layer adsorption and reaction (SILAR) exhibit limited absorption below 500 nm with a net power conversion efficiency of ∼1% when employed as a photoanode in QDSC. By depositing a thin barrier layer of Al2O3, the TiO2-CdS films were further modified with a NIR absorbing squaraine dye. Quantum dot sensitized solar cells supersensitized with a squariand dye (JK-216) showed good stability during illumination with standard global AM 1.5 solar conditions, delivering a maximum overall power conversion efficiency () of 3.14%. Transient absorption and pulse radiolysis measurements provide further insight into the excited state interactions of squaraine dye with SiO 2, TiO2, and TiO2/CdS/Al2O 3 films and interfacial electron transfer processes. The synergy of combining semiconductor quantum dots and NIR absorbing dye provides new opportunities to harvest photons from different regions of the solar spectrum. © 2011 American Chemical Society.

Chen G.,State University of New York at Buffalo | Chen G.,Harbin Institute of Technology | Agren H.,KTH Royal Institute of Technology | Ohulchanskyy T.Y.,State University of New York at Buffalo | And 2 more authors.
Chemical Society Reviews | Year: 2015

Light upconverting nanostructures employing lanthanide ions constitute an emerging research field recognized with wide ramifications and impact in many areas ranging from healthcare, to energy and, to security. The core-shell design of these nanostructures allows us to deliberately introduce a hierarchy of electronic energy states, thus providing unprecedented opportunities to manipulate the electronic excitation, energy transfer and upconverted emissions. The core-shell morphology also causes the suppression of quenching mechanisms to produce efficient upconversion emission for biophotonic and photonic applications. Using hierarchical architect, whereby each shell layer can be defined to have a specific feature, the electronic structure as well as the physiochemical structure of the upconverting nanomaterials can be tuned to couple other electronic states on the surface such as excitations of organic dye molecules or localized surface plasmons from metallic nanostructures, or to introduce a broad range of imaging or therapeutic modalities into a single conduct. In this review, we summarize the key aspects of nanophotonic control of the light upconverting nanoparticles through governed design and preparation of hierarchical shells in the core-shell nanostructures, and review their emerging applications in the biomedical field, solar energy conversion, as well as security encoding. This journal is © The Royal Society of Chemistry.

Lee J.-N.,Korea University | Choi B.,Kookmin University
Information and Management | Year: 2011

Much has been written about the need for trust in outsourcing relationships, but the literature has produced only a few theoretical models that explain the process that helps it evolve. We proposed a theoretical model by distinguishing ongoing beliefs, such as ongoing trust and distrust, from initial perceptions, such as initial trust and distrust, in the context of IT outsourcing, and then explored empirically how these interacted with one another the knowledge sharing experience between the participants, thus leading to a successful experience from both the outsourcer and the service provider. The model and its hypotheses were tested using two-stage survey data collected from IT outsourcing projects. Our results showed that the ongoing trust and distrust between the receiver and provider were crucial in attaining benefits and that the outcome was also affected by the perceptions of the participants at the initial stage of the outsourcing process. We also found that knowledge-sharing experience between the parties moderated the impact of initial trust or distrust on the ongoing trust or distrust in different ways: the change in the service provider's initial perceptions were apparently more visible and positive than those of the service receiver's, although both initial perceptions tended to be cognitively consistent. These results helped us understand how trust evolves over time in an outsourcing relationship, and enabled us to explore the different viewpoints of the service provider and receiver. © 2011 Elsevier B.V. All rights reserved.

Hovav A.,Korea University | D'Arcy J.,University of Notre Dame
Information and Management | Year: 2012

Intentional employee misuse of IS is a global problem. Research suggests that security countermeasures can deter misuse by increasing the perceived certainty and severity of punishment for such behavior. However, the value of generalizing this work beyond Western cultures is open to question. In our study, we examined whether national culture influenced the deterrent capabilities of security policies, security education, training, and awareness programs and computer monitoring. Using U.S. and Korean samples, we found evidence that the deterrent effect of certain security countermeasures varied between the two countries, as did the influence of age and gender. The results have implications for information security management practices in global businesses. © 2011 Elsevier B.V.

Yeom J.,Korea University | Imlay J.A.,University of Illinois at Urbana - Champaign | Park W.,Korea University
Journal of Biological Chemistry | Year: 2010

Antibiotics can induce cell death via a variety of action modes, including the inhibition of transcription, ribosomal function, and cell wall biosynthesis. In this study, we demonstrated directly that iron availability is important to the action of antibiotics, and the ferric reductases of Pseudomonas putida and Pseudomonas aeruginosa could accelerate antibiotic-mediated cell death by promoting the Fenton reaction. The modulation of reduced nicotinamide-adenine dinucleotide (NADH) levels and iron chelation affected the actions of antibiotics. Interestingly, the deletion of the ferric reductase gene confers more antibiotic resistance upon cells, and its overexpression accelerates antibiotic-mediated cell death. The results of transcriptome analysis showed that both Pseudomonas species induce many oxidative stress genes under antibiotic conditions, which could not be observed in ferric reductase mutants. Our results indicate that iron homeostasis is crucial for bacterial cell survival under antibiotics and should constitute a significant target for boosting the action of antibiotics. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Dong A ST Co. and Korea University | Date: 2016-05-04

The present invention relates to a composition for preventing or treating renal diseases. The composition of the present invention improves lipid metabolism, prevents histological damage including renal fibrosis, alleviates microalbuminuria, and maintains nephrons of renal glomeruli. Therefore, the composition is useful for treating renal diseases.

Dong A St Co. and Korea University | Date: 2014-06-17

The present invention relates to a composition for preventing or treating renal diseases. The composition of the present invention improves lipid metabolism, prevents histological damage including renal fibrosis, alleviates microalbuminuria, and maintains nephrons of renal glomeruli. Therefore, the composition is useful for treating renal diseases.

Kim K.-W.,Pohang University of Science and Technology | Lee H.-W.,Pohang University of Science and Technology | Lee K.-J.,Korea University | Stiles M.D.,U.S. National Institute of Standards and Technology
Physical Review Letters | Year: 2013

As nanomagnetic devices scale to smaller sizes, spin-orbit coupling due to the broken structural inversion symmetry at interfaces becomes increasingly important. Here, we study interfacial spin-orbit coupling effects in magnetic bilayers using a simple Rashba model. The spin-orbit coupling introduces chirality into the behavior of the electrons and through them into the energetics of the magnetization. In the derived form of the magnetization dynamics, all of the contributions that are linear in the spin-orbit coupling follow from this chirality, considerably simplifying the analysis. For these systems, an important consequence is a correlation between the Dzyaloshinskii-Moriya interaction and the spin-orbit torque. We use this correlation to analyze recent experiments. © 2013 American Physical Society.

Quang D.T.,Hue University | Kim J.S.,Korea University
Chemical Reviews | Year: 2010

Several researchers conducted studies to demonstrate the use of fluoro- and chromogenic chemodosimeters for heavy metal ion detection in solution and biospecimens. They demonstrated that fluorescent chemodosimeters had emerged as as a research area of significant importance due to their potential in detecting heavy metal ions in solution and biospecimens. Chemodosimeters were used to detect an analyte through a highly selective and irreversible chemical reaction between the dosimeter molecule and the target analyte. This led to an observable signal that had an accumulative effect and was directly related to the concentration of the analyte. The chemodosimeter also provided signaling changes in absorption wavelength and color that were widely used as detection events, as they required only the use of cost-effective equipment or no equipment in some cases.

Kim K.-W.,Pohang University of Science and Technology | Moon J.-H.,Korea University | Lee K.-J.,Korea University | Lee H.-W.,Pohang University of Science and Technology
Physical Review Letters | Year: 2012

Magnetization dynamics in a ferromagnet can induce a spin-dependent electric field through a spin motive force. Spin current generated by the spin-dependent electric field can in turn modify the magnetization dynamics through spin-transfer torque. While this feedback effect is usually weak and thus ignored, we predict that in Rashba spin-orbit coupling systems with a large Rashba parameter α R, the coupling generates the spin-dependent electric field [±(α Rm e/e)(z×-m/-t)], which can be large enough to modify the magnetization dynamics significantly. This effect should be relevant for device applications based on ultrathin magnetic layers with strong Rashba spin-orbit coupling. © 2012 American Physical Society.

Kim J.,Hong Kong University of Science and Technology | Kim J.,Korea University | Mok P.K.T.,Hong Kong University of Science and Technology | Kim C.,Korea University
Digest of Technical Papers - IEEE International Solid-State Circuits Conference | Year: 2014

Design of low-voltage and efficient energy-harvesting circuits is becoming increasingly important, particularly, for autonomous systems. Since the amount of energy that can be harvested from the surrounding environment is limited, the available output voltage of a harvester is low. Therefore, the design of a low-input-voltage (low-VIN) up-converter is critical to self-powered systems [1-3]. Moreover, the form factor is very constrained in applications such as wearable electronic devices and sensor networks. Recently, low-V IN charge pumps (CPs) for energy harvesting has been compared with DC-DC converters using a large inductor [1-3]. CPs introduced in [1] and [2] use the advanced process technology to push VIN down to the subthreshold region. The CP in [1] introduces a forward-body-biasing (FBB) technique, which improves the voltage conversion efficiency (VCE) for low VIN but shows poor power conversion efficiency (PCE). The CP in [2] achieves the lowest operation voltage. However, the design with a 10-stage CP provides low output power. This paper presents a CP with switching-body-biasing (SBB), adaptive-dead-time (AD), and switch-conductance (SW-G) enhancement techniques to improve the PCE for low VIN as well as to extend the maximum load current. © 2014 IEEE.

Lee B.-H.,Korea University | Lee B.-H.,KARF Hospital | Kim Y.-K.,Korea University
Journal of Affective Disorders | Year: 2012

Background: The neurotrophic hypothesis suggests that mood disorders are associated with dysfunction of neuronal networks under the influence of neurotrophic factors. Vascular endothelial growth factor (VEGF) is a neurotrophic factor as well as an angiogenic cytokine. Methods: We examined plasma VEGF levels in 35 unipolar patients who were diagnosed with current major depressive disorder (MDD), 35 bipolar patients who were diagnosed with bipolar I disorder, manic episode (BM), and 60 healthy controls. The severity of depressive or manic symptoms was measured using the Hamilton Depression Rating Scale (HDRS) or the Young Mania rating scale (YMRS), respectively. Results: Plasma VEGF levels were 163.28 ± 135.33 pg/mL in MDD patients, 199.82 ± 182.59 pg/mL in BM patients, and 110.05 ± 109.57 pg/mL in healthy controls. Both MDD and BM patients had significantly higher VEGF levels than healthy controls when controlling for BMI as a covariate (p = 0.010). Patients' VEGF levels were not correlated with either HDRS or YMRS scores. Limitations: We assessed plasma VEGF levels at one time point, and we did not determine the source of VEGF in our samples. Conclusions: Plasma VEGF levels were elevated in patients with acute episodes of major depressive disorder and bipolar disorder. Such an alteration of VEGF in acute episode, mood disorders may be associated with a neuroprotective role for VEGF. © 2011 Elsevier B.V.

Kim G.,Korea University | Jeong S.,Ulsan National Institute of Science and Technology | Shin J.-H.,Korea University | Cho J.,Ulsan National Institute of Science and Technology | Lee H.,Korea University
ACS Nano | Year: 2014

We present an amorphous Si anode deposited on a Cu nanopillar current collector, fabricated using a thermal roll-to-roll process followed by electroformation and LPCVD, for application in high-rate Li-ion batteries. Cu nanopillar current collectors with diameters of 250 and 500 nm were patterned periodically with 1 μm pitch and 2 μm height to optimize the diameters of the pillars for better electrochemical performance. Void spaces between Cu nanopillars allowed not only greater effective control of the strain caused by the Si expansion during lithiation than that allowed by a nonpatterned electrode but also significantly improved cycle performance even at 20 C measured after the same rate test: After 100 cycles at 0.5 C, the patterned electrodes with 250 and 500 nm diameter nanopillars showed high capacity retentions of 86% and 84%, respectively. These electrodes retained discharge capacities of 1057 and 780 mAh/g even at 20 C, respectively. © 2014 American Chemical Society.

Engels E.A.,U.S. National Cancer Institute | Cho E.R.,Korea University | Jee S.H.,Institute for Health Promotion
The Lancet Oncology | Year: 2010

Background: Hepatitis B virus (HBV) infection is common throughout Asia and Africa. Whether chronic HBV infection increases risk of non-Hodgkin lymphoma (NHL) is unclear. We aimed to assess the association between chronic HBV infection and subsequent development of NHL in a South Korean cohort. Methods: The Korean Cancer Prevention Study is a cohort study of South Korean workers and their dependants enrolled during 1992-95. From this cohort, we excluded individuals who died before Jan 1, 1993, who had cancer at or before the initial visit, who had missing information about weight, height, alanine aminotransferase or aspartate aminotransferase concentrations, or alcohol use, or who had evidence of HIV or HCV infection. Of 1 284 586 eligible participants, 603 585 had baseline data for serum hepatitis B surface antigen (HBsAg) status and were included in our study. We regarded HBsAg positivity at baseline as evidence of chronic HBV infection. Participants were followed up from baseline until Dec 31, 2006. We used national databases of inpatient and outpatient diagnoses and mortality records to ascertain occurrence of haematological malignancies. We assessed incidence of NHL overall and of NHL subtypes, malignant immunoproliferation, Hodgkin's lymphoma, multiple myeloma, and various leukaemias. We used Cox regression to evaluate associations with HBsAg status, adjusting for sex, age, and enrolment year. Findings: 53 045 (9%) of 603 585 participants tested positive for HBsAg at baseline. Subsequently, 133 HBsAg-positive and 905 HBsAg-negative individuals developed NHL. HBsAg-positive participants had an increased risk of NHL overall compared with those who were HBsAg-negative (incidence 19·4 vs 12·3 per 100 000 person-years; hazard ratio [HR] 1·74, 95% CI 1·45-2·09, adjusted for sex, age at baseline, and enrolment year). Among NHL subtypes, HBsAg positivity was associated with increased risk of diffuse large B-cell lymphoma (n=325, incidence 6·86 vs 3·79 per 100 000 person-years; adjusted HR 2·01, 1·48-2·75) and other or unknown subtypes (n=591, incidence 10·5 vs 7·07 per 100 000 person-years; adjusted HR 1·65, 1·29-2·11), compared with HBsAg negativity. Increased risk was also recorded for malignant immunoproliferation (n=14, incidence 0·44 vs 0·15 per 100 000 person-years; adjusted HR 3·79, 1·05-13·7). Risk of these malignancies was consistently raised in HBsAg-positive participants throughout 14 years of follow-up. HBsAg positivity was not associated with follicular or T-cell NHL, Hodgkin's lymphoma, multiple myeloma, or various leukaemias. Interpretation: During extended follow-up, HBsAg-positive individuals had an increased risk of NHL, suggesting that chronic HBV infection promotes lymphomagenesis. Funding: Korean Seoul City Research and the National Research and Development Program for Cancer Control, Ministry for Health, Welfare and Family Affairs, Republic of Korea; US National Cancer Institute. © 2010 Elsevier Ltd.

Choi D.S.,Korea University | Hwang I.S.,Korea University | Hwang I.S.,Boyce Thompson Institute for Plant Research | Hwang B.K.,Korea University
Plant Cell | Year: 2012

Plants recruit innate immune receptors such as leucine-rich repeat (LRR) proteins to recognize pathogen attack and activate defense genes. Here, we identified the pepper (Capsicum annuum) pathogenesis-related protein10 (PR10) as a leucine-rich repeat protein1 (LRR1)-interacting partner. Bimolecular fluorescence complementation and coimmunoprecipitation assays confirmed the specific interaction between LRR1 and PR10 in planta. Avirulent Xanthomonas campestris pv vesicatoria infection induces PR10 expression associated with the hypersensitive cell death response. Transient expression of PR10 triggers hypersensitive cell death in pepper and Nicotiana benthamiana leaves, which is amplified by LRR1 coexpression as a positive regulator. LRR1 promotes the ribonuclease activity and phosphorylation of PR10, leading to enhanced cell death signaling. The LRR1-PR10 complex is formed in the cytoplasm, resulting in its secretion into the apoplastic space. Engineered nuclear confinement of both proteins revealed that the cytoplasmic localization of the PR10- LRR1 complex is essential for cell death-mediated defense signaling. PR10/LRR1 silencing in pepper compromises resistance to avirulent X. campestris pv vesicatoria infection. By contrast, PR10/LRR1 overexpression in Arabidopsis thaliana confers enhanced resistance to Pseudomonas syringae pv tomato and Hyaloperonospora arabidopsidis. Together, these results suggest that the cytosolic LRR-PR10 complex is responsible for cell death-mediated defense signaling. © 2012 American Society of Plant Biologists. All rights reserved.

Hwang M.-J.,Pohang University of Science and Technology | Choi M.-S.,Korea University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

The nonclassical behavior of a two-level system coupled to a harmonic oscillator is investigated in the ultrastrong coupling regime. We revisit the variational solution of the ground state and find that the existing solutions do not account accurately for nonclassical effects such as squeezing. We suggest a trial wave function and demonstrate that it has an excellent accuracy for the quantum correlation effects as well as for the energy. © 2010 The American Physical Society.

Lee E.S.,Korea University | Jeon T.-I.,Korea University | Jeon T.-I.,Center for Subwavelength Optics
Optics Express | Year: 2012

A single groove in a parallel-plate waveguide (PPWG) has been applied to a tunable terahertz (THz) notch filter with a transverseelectromagnetic (TEM) mode. When the air gap between the metal plates of the PPWG is controlled from 60 to 240 μm using a motor controlled translation stage or a piezo-actuator, the resonant frequency of the notch filter is changed from 1.75 up to 0.62 THz, respectively. Therefore, the measured tunable sensitivity of the notch filter increases to 6.28 GHz/μm. The measured resonant frequencies were found to be in good agreement with the calculation using an effective groove depth. Using a finitedifference time-domain (FDTD) simulation, we also demonstrate that the sensitivity of a THz microfluidic sensor can be increased via a small air gap, a narrow groove width, and a deep groove depth. © 2012 Optical Society of America.

Kong J.,Korea University | Chung S.W.,Korea University | Skadron K.,University of Virginia
ACM Computing Surveys | Year: 2012

Microprocessor design has recently encountered many constraints such as power, energy, reliability, and temperature. Among these challenging issues, temperature-related issues have become especially important within the past several years. We summarize recent thermal management techniques for microprocessors, focusing on those that affect or rely on themicroarchitecture. We categorize thermal management techniques into sixmain categories: temperaturemonitoring, microarchitectural techniques, floorplanning, OS/compiler techniques, liquid cooling techniques, and thermal reliability/security. Temperature monitoring, a requirement for Dynamic Thermal Management (DTM), includes temperature estimation and sensor placement techniques for accurate temperature measurement or estimation. Microarchitectural techniques include both static and dynamic thermal management techniques that control hardware structures. Floorplanning covers a range of thermal-aware floorplanning techniques for 2D and 3D microprocessors. OS/compiler techniques include thermal-aware task scheduling and instruction scheduling techniques. Liquid cooling techniques are higher-capacity alternatives to conventional air cooling techniques. Thermal reliability/security issues cover temperature-dependent reliability modeling, Dynamic Reliability Management (DRM), and malicious codes that specifically cause overheating. Temperature-related issues will only become more challenging as process technology continues to evolve and transistor densities scale up faster than power per transistor scales down. The overall objective of this survey is to give microprocessor designers a broad perspective on various aspects of designing thermal-aware microprocessors and to guide future thermal management studies. © 2012 ACM.

Kral C.,Austrian Institute of Technology GmbH | Haumer A.,Technical Consulting and Electrical Engineering | Lee S.B.,Korea University
IEEE Transactions on Power Electronics | Year: 2014

A thermal model for the determination of the temperatures of interior permanent magnets and stator windings is presented in this paper. The innovation of the model relies on one temperature sensor being located in the stator core of the machine. Such sensor is simple to implement in many applications such as traction or EV, where reliability is critical. The estimated stator winding and permanent magnet temperatures are determined by a simplified thermal lumped element network model with only two time constants. It is shown that the proposed thermal model is very robust due to the structure of the model and the measured stator core temperature. The distortion of the temperature estimates caused by the cooling circuit is inherently accounted for such that the model can be used for robust online prediction of temperatures. Experimental results based on a forced water-cooled interior permanent magnet synchronous machine setup are presented to validate the effectiveness of the presented model. © 1986-2012 IEEE.

Choi J.S.,University of Rochester | Cho M.,Korea University | Cho M.,Korea Basic Science Institute
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

Recently, Tang and Cohen proposed and demonstrated the use of "superchiral" electromagnetic fields to enhance optical enantioselectivity. Their work generated much excitement as enantioselective signals are typically quite small, and it appeared that the enhancement factor could be extremely large. In this paper we explicitly show the limitations of such fields by including the magnetic susceptibility term. This term is small and is ignored in most cases compared to the electric polarizability term. However, for the fields used, the enhancement was obtained at the electric field energy node. Due to conservation of field energy, the magnetic field energy is then maximum, and the magnetic susceptibility contribution can no longer be ignored. This then is what limits the enhancement of the optical enantioselectivity. For a counterpropagating left- and right-circularly polarized light field, as used in the aforementioned experiment, we show that this fundamentally limits the enhancement to one or two orders of magnitude in general, determined by the ratio of the magnetic susceptibility to the electric polarizability of the material used. We also generalize the dissymmetry factor to include optical rotation effects present in chiral media, as opposed to fields being in vacuum. In the process, we generalize Lipkin's "Z000 zilch" (or "optical chirality") to that for a linear medium. This generalization shows that chirality of the material cannot be completely separated from chirality of the field and that opposite enantiomers are symmetric in terms of the dissymmetry factor enhancement. Finally, an analogy between ellipsometric chiroptical signal enhancement and enhanced optical enantioselectivity using a standing wave chiral field is discussed. Our analysis and generalization can be used as a guide for future searches of locally enhanced chiral fields. © 2012 American Physical Society.

Feng J.,Tsinghua University | Jain A.K.,Michigan State University | Jain A.K.,Korea University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2011

Fingerprint matching systems generally use four types of representation schemes: grayscale image, phase image, skeleton image, and minutiae, among which minutiae-based representation is the most widely adopted one. The compactness of minutiae representation has created an impression that the minutiae template does not contain sufficient information to allow the reconstruction of the original grayscale fingerprint image. This belief has now been shown to be false; several algorithms have been proposed that can reconstruct fingerprint images from minutiae templates. These techniques try to either reconstruct the skeleton image, which is then converted into the grayscale image, or reconstruct the grayscale image directly from the minutiae template. However, they have a common drawback: Many spurious minutiae not included in the original minutiae template are generated in the reconstructed image. Moreover, some of these reconstruction techniques can only generate a partial fingerprint. In this paper, a novel fingerprint reconstruction algorithm is proposed to reconstruct the phase image, which is then converted into the grayscale image. The proposed reconstruction algorithm not only gives the whole fingerprint, but the reconstructed fingerprint contains very few spurious minutiae. Specifically, a fingerprint image is represented as a phase image which consists of the continuous phase and the spiral phase (which corresponds to minutiae). An algorithm is proposed to reconstruct the continuous phase from minutiae. The proposed reconstruction algorithm has been evaluated with respect to the success rates of type-I attack (match the reconstructed fingerprint against the original fingerprint) and type-II attack (match the reconstructed fingerprint against different impressions of the original fingerprint) using a commercial fingerprint recognition system. Given the reconstructed image from our algorithm, we show that both types of attacks can be successfully launched against a fingerprint recognition system. © 2011 IEEE.

Yoo S.-H.,Hoseo University | Kwak S.-Y.,Korea University
Energy Policy | Year: 2010

This paper attempts to investigate the causal relationship between electricity consumption and economic growth among seven South American countries, namely Argentina, Brazil, Chile, Columbia, Ecuador, Peru, and Venezuela using widely accepted time-series techniques for the period 1975-2006. The results indicate that the causal nexus between electricity consumption and economic growth varies across countries. There is a unidirectional, short-run causality from electricity consumption to real GDP for Argentina, Brazil, Chile, Columbia, and Ecuador. This means that an increase in electricity consumption directly affects economic growth in those countries. In Venezuela, there is a bidirectional causality between electricity consumption and economic growth. This implies that an increase in electricity consumption directly affects economic growth and that economic growth also stimulates further electricity consumption in that country. However, no causal relationships exist in Peru. The documented evidence from seven South American countries can provide useful information for each government with regard to energy and growth policy. © 2009 Elsevier Ltd. All rights reserved.

Ku S.-J.,Korea University | Yoo S.-H.,Hoseo University
Renewable and Sustainable Energy Reviews | Year: 2010

Renewable energy sources are considered as alternatives for coping with the high price of oil and global warming. The Korean government has set a target that 11% of the total primary energy supply should be obtained through renewable energy sources until 2030. In order to develop proper policies for renewable energy investment, it is necessary to analyze the benefits of renewable energy investment based on households' willingness to pay. This study attempts to apply a choice experiment (CE) for assessing renewable energy investment in Korea. Moreover, we employ a multinomial probit (MNP) model to relax the assumption that all respondents have the same preferences for the attributes being valued, which is usually required in empirical CE studies. An MNP model allows the most flexible pattern of error correlation structure. The results reveal that the Korean public puts a value on the protection of wildlife, reduction of pollution, and increased employment opportunities. On the other hand, respondents do not derive significant values from the improvement of landscapes. This study is expected to provide policy-makers with useful information for evaluating and planning policies related to renewable energy investment. © 2010 Elsevier Ltd.

Hsu C.,National Taiwan University | Lee J.-N.,Korea University | Straub D.W.,Georgia State University
Information Systems Research | Year: 2012

This research investigates information security management as an administrative innovation. Although a number of institutional theories deal with information systems (IS) innovation in organizations, most of these institutional-centered frameworks overlook external economic efficiency and internal organizational capability in the presence of pressures of institutional conformity. Using Korea as the institutional setting, our research model posits that economic-based consideration will moderate the institutional conformity pressure on information security adoption while organization capability will influence the institutional confirmation of information security assimilation. The model is empirically tested using two-stage survey data from a field study of 140 organizations in Korea. The results indicate that in addition to institutional influences, our six proposed economic-based and organizational capability moderating variables all have significant influences on the degree of the adoption and assimilation of information security management. We conclude with implications for research in the area of organizational theory and the information security management literature, and for practices regarding how managers can factor into their information security planning the key implementation variables discovered in this study. The robust setting of the study in Korean firms allows us to generalize the theory to a new context and across cultures. © 2012 INFORMS.

Hong K.-S.,Ilsan Paik Hospital | Yegiaian S.,University of California at Los Angeles | Lee M.,Chang Gung University | Lee J.,Korea University | Saver J.L.,University of California at Los Angeles
Circulation | Year: 2011

Background: It is widely supposed, but not well-demonstrated, that cumulative advances in standard care have reduced recurrent stroke and cardiovascular events in secondary prevention trials. Methods and results: Systematic search identified all randomized, controlled trials of medical secondary stroke prevention therapies published from 1960 to 2009. Randomized, controlled trials narrowly focused on single stroke mechanisms, including atrial fibrillation, cervical carotid stenosis, and intracranial stenosis, were excluded. From control arms of individual trials, we extracted data for baseline characteristics and annual event rates for recurrent stroke, fatal stroke, and major vascular events and analyzed trends over time. Fifty-nine randomized controlled trials were identified, enrolling 66 157 patients in control arms. Over the 5 decade periods, annual event rates declined, per decade, for recurrent stroke by 0.996% (P=0.001), fatal stroke by 0.282% (P=0.003), and major vascular events by 1.331% (P=0.001). Multiple regression analyses identified increasing antithrombotic use and lower blood pressures as major contributors to the decline in recurrent stroke. For recurrent stroke, annual rates fell from 8.71% in trials launched in the 1960s to 6.10% in the 1970s, 5.41% in the 1980s, 4.04% in the 1990s, and 4.98% in the 2000s. The sample size required for a trial to have adequate power to detect a 20% reduction in recurrent stroke increased 2.2-fold during this period. Conclusions: Recurrent stroke and vascular event rates have declined substantially over the last 5 decades, with improved blood pressure control and more frequent use of antiplatelet therapy as the leading causes. Considerably larger sample sizes are now needed to demonstrate incremental improvements in medical secondary prevention. © 2011 American Heart Association, Inc.

Kim B.,Korea University | Ruhm C.J.,University of Virginia
Health Economics | Year: 2012

We examine how wealth shocks, in the form of inheritances, affect the mortality rates, health status and health behaviors of older adults, using data from eight waves of the Health and Retirement Survey. Our main finding is that bequests do not have substantial effects on health, although improvements in quality-of-life are possible. This absence occurs despite increases in out-of-pocket spending on healthcare and in the utilization of medical services, especially discretionary and non-lifesaving types such as dental care. Nor can we find a convincing indication of changes in lifestyles that offset the benefits of increased medical care. Inheritances are associated with higher alcohol consumption, but with no change in smoking or exercise and a possible decrease in obesity. Copyright © 2010 John Wiley & Sons, Ltd.

The present invention relates to a complex of a protein comprising zinc oxide-binding peptides and zinc oxide nanoparticles, to the use thereof as a drug delivery carrier for manufacturing medicines, and to a vaccine composition and a contrast agent comprising the composite. The protein comprising zinc oxide-binding peptides significantly improves the in vivo availability of zinc oxide-binding peptides, and therefore the complex of the present invention can be used not only as a drug delivery carrier for in vivo drug delivery or intracellular drug delivery, but also for in vivo imaging or cell imaging. The complex can be used for producing separating agents for effectively separating biological materials, therapeutic agents for hyperthermia, etc., contrast agents for MRI, and beads applicable to biosensors.

The present invention relates to a complex of a protein comprising zinc oxide-binding peptides and zinc oxide nanoparticles, to the use thereof as a drug delivery carrier for manufacturing medicines, and to a vaccine composition and a contrast agent comprising the composite. The protein comprising zinc oxide-binding peptides significantly improves the in vivo availability of zinc oxide-binding peptides, and therefore the complex of the present invention can be used not only as a drug delivery carrier for in vivo drug delivery or intracellular drug delivery, but also for in vivo imaging or cell imaging. The complex can be used for producing separating agents for effectively separating biological materials, therapeutic agents for hyperthermia, etc., contrast agents for MRI, and beads applicable to biosensors.

The present invention relates to a complex prepared by conjugating indocyanine green to mannosyl serum albumin in order to overcome shortcomings such as low light stability and low in vivo stability of indocyanine green that is a fluorescent dye reagent that is used during surgical operations, a preparation method thereof, an optical imaging probe comprising the same, and a kit comprising the probe.

Hwang Y.H.,Konyang University | Kim Y.Y.,Korea University | Kim H.K.,Konyang University | Sohn Y.H.,Konyang University
Ophthalmology | Year: 2013

Purpose: To investigate the ability of clock-hour, deviation, and thickness maps of Cirrus high-definition spectral-domain optical coherence tomography (HD-OCT) in detecting retinal nerve fiber layer (RNFL) defects identified in red-free fundus photographs in eyes with early glaucoma (mean deviation >-6.0 dB). Design: Cross-sectional study. Participants: Two hundred ninety-five eyes with glaucomatous RNFL defects with clear margins observed in red-free fundus photographs and 200 age-, sex-, and refractive error-matched healthy eyes were enrolled. Methods: The width and location of RNFL defects were evaluated by using the red-free fundus photograph. When a RNFL defect detected by red-free fundus photograph did not present as (1) yellow/red codes in the clock-hour map, (2) yellow/red pixels in the deviation map, or (3) blue/black areas in the thickness map, the event was classified as a misidentification of a photographic RNFL defect by Cirrus HD-OCT. In healthy eyes, the presence of false-positive RNFL color codes of Cirrus HD-OCT maps was investigated. Main Outcome Measures: The prevalence of and factors associated with the (1) misidentification of photographic RNFL defects by Cirrus HD-OCT in eyes with glaucoma and (2) false-positive RNFL color codes of Cirrus HD-OCT maps in healthy eyes were assessed. Results: Among the 295 red-free fundus photographic RNFL defects from 295 eyes with glaucoma, 83 (28.1%), 27 (9.2%), and 0 (0%) defects were misidentified in the clock-hour, deviation, and thickness maps of Cirrus HD-OCT, respectively. Fifty-six defects (19.0%) were misidentified only in the clock-hour map and 27 (9.2%) in both the clock-hour and deviation maps. The misidentification of photographic RNFL defects by Cirrus HD-OCT was associated with a narrower width and a temporal location of RNFL defects (P<0.05). Among the 200 healthy eyes, 25 (12.5%), 30 (15.0%), and 12 (6.0%) eyes had false-positive RNFL color codes in clock-hour, deviation, and thickness maps of Cirrus HD-OCT, respectively. Conclusions: Among the clock-hour, deviation, and thickness maps obtained with Cirrus HD-OCT, the thickness map showed the best diagnostic ability in detecting photographic RNFL defects. The RNFL thickness map may be a useful tool for the detection of RNFL defects in eyes with early glaucoma. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article. © 2013 American Academy of Ophthalmology.

Chen G.,Harbin Institute of Technology | Chen G.,State University of New York at Buffalo | Qiu H.,Harbin Institute of Technology | Qiu H.,State University of New York at Buffalo | And 3 more authors.
Chemical Reviews | Year: 2014

Theranostics is a concept of integrating imaging and therapy into a single platform for use in the next generation of personalized medicine to meet the challenges in modern health care. The diagnostic role of theranostic agents reports the presence of a disease, its status, and its response to a specific treatment, while the therapeutic role of the agent can be implemented in several forms. Two-photon-excitation or second harmonic generation contrast agents, which utilize longer wavelength light, have been recently developed to overcome these limitations for imaging of cells and small animals. However, they require expensive ultrashort pulsed lasers to perform the excitation as they involve inefficient nonlinear optical processes. For bioimaging, some of the advantages are virtually zero autofluorescence background to improve signal-to-noise ratio, large anti-Stokes shifts allowing us to easily separate the PL from the excitation wavelength, narrow emission bandwidths allowing ease of multiplexed imaging.

Park S.W.,Korea University | Colvin C.R.,Northeastern University
Journal of Personality | Year: 2015

The relation between narcissism and other-derogation has been examined primarily in the context of ego threat. In three studies, we investigated whether narcissistic individuals derogate others in the absence of ego threat. In Study 1, 79 judges watched four videotaped dyadic interactions and rated the personality of the same four people. In Study 2, 66 judges rated the personality of a friend. In Study 3, 72 judges considered the average Northeastern University student and rated the personality of this hypothetical person. Across the three studies, targets' personality characteristics were described on the 100-item California Adult Q-Sort (CAQ; Block, 2008). Judges' ratings of targets were compared to a CAQ prototype of the optimally adjusted person to assess target-derogation. Judges' narcissism and other-derogation were positively related in Studies 1 and 2. Narcissism positively predicted and self-esteem negatively predicted target-derogation after controlling for each other in Study 3. Narcissistic individuals derogate others more than non-narcissistic individuals regardless of whether ego threat is present or absent. © 2014 Wiley Periodicals, Inc.

Chen G.,Harbin Institute of Technology | Chen G.,State University of New York at Buffalo | Seo J.,State University of New York at Buffalo | Seo J.,Seoul National University | And 3 more authors.
Chemical Society Reviews | Year: 2013

Nanochemistry and nanomaterials provide numerous opportunities for a new generation of photovoltaics with high solar energy conversion efficiencies at low fabrication cost. Quantum-confined nanomaterials and polymer-inorganic nanocomposites can be tailored to harvest sun light over a broad range of the spectrum, while plasmonic structures offer effective ways to reduce the thickness of light-absorbing layers. Multiple exciton generation, singlet exciton fission, photon down-conversion, and photon up-conversion realized in nanostructures, create significant interest for harvesting underutilized ultraviolet and currently unutilized infrared photons. Nanochemical interface engineering of nanoparticle surfaces and junction-interfaces enable enhanced charge separation and collection. In this review, we survey these recent advances employed to introduce new concepts for improving the solar energy conversion efficiency, and reduce the device fabrication cost in photovoltaic technologies. The review concludes with a summary of contributions already made by nanochemistry. It then describes the challenges and opportunities in photovoltaics where the chemical community can play a vital role. This journal is © The Royal Society of Chemistry 2013.

Kwon S.,Korea University | Wang J.,Rutgers University | Shim B.,Korea University
IEEE Transactions on Information Theory | Year: 2014

In this paper, we propose an algorithm referred to as multipath matching pursuit (MMP) that investigates multiple promising candidates to recover sparse signals from compressed measurements. Our method is inspired by the fact that the problem to find the candidate that minimizes the residual is readily modeled as a combinatoric tree search problem and the greedy search strategy is a good fit for solving this problem. In the empirical results as well as the restricted isometry property-based performance guarantee, we show that the proposed MMP algorithm is effective in reconstructing original sparse signals for both noiseless and noisy scenarios. © 1963-2012 IEEE.

Chen G.,Harbin Institute of Technology | Chen G.,State University of New York at Buffalo | Yang C.,Harbin Institute of Technology | Prasad P.N.,State University of New York at Buffalo | Prasad P.N.,Korea University
Accounts of Chemical Research | Year: 2013

Nanophotonics is an emerging science dealing with the interaction of light and matter on a nanometer scale and holds promise to produce new generation nanophosphors with highly efficient frequency conversion of infrared (IR) light. Scientists can control the excitation dynamics by using nanochemistry to produce hierarchically built nanostructures and tailor their interfaces. These nanophosphors can either perform frequency up-conversion from IR to visible or ultraviolet (UV) or down-conversion, which results in the IR light being further red shifted. Nanophotonics and nanochemistry open up numerous opportunities for these photon converters, including in high contrast bioimaging, photodynamic therapy, drug release and gene delivery, nanothermometry, and solar cells. Applications of these nanophosphors in these directions derive from three main stimuli. Light excitation and emission within the near-infrared (NIR) "optical transparency window" of tissues is ideal for high contrast in vitro and in vivo imaging. This is due to low natural florescence, reduced scattering background, and deep penetration in tissues. Secondly, the naked eye is highly sensitive in the visible range, but it has no response to IR light. Therefore, many scientists have interest in the frequency up-conversion of IR wavelengths for security and display applications. Lastly, frequency up-conversion can convert IR photons to higher energy photons, which can then readily be absorbed by solar materials. Current solar devices do not use abundant IR light that comprises almost half of solar energy.In this Account, we present our recent work on nanophotonic control of frequency up- and down-conversion in fluoride nanophosphors, and their biophotonic and nanophotonic applications. Through nanoscopic control of phonon dynamics, electronic energy transfer, local crystal field, and surface-induced non-radiative processes, we were able to produce new generation nanophosphors with highly efficient frequency conversion of IR light. We show that nanochemistry plays a vital role in the design and interface engineering of nanophosphors, providing pathways to expand their range of applications. High contrast in vitro and in vivo NIR-to-NIR up- and down-conversion bioimaging were successfully demonstrated by our group, evoking wide interests along this line. We introduced trivalent gadolinium ions into the lattice of the nanophosphors or into the shell layer of nanophosphors in a core/shell configuration to produce novel nanophosphors for multimodal (MRI and optical) imaging. We also demonstrate the security and display applications using photopatternable NIR-to-NIR and NIR-to-visible frequency up-conversion nanophosphors with appropriately engineered surface chemistry. In addition, we present preliminary results on dye-sensitized solar cells using up-conversion in fluoride lattice-based nanophosphors for IR photon harvesting. © 2013 American Chemical Society.

Seoul National University of Science, Technology, Korea University and Advanced Digital Chips Inc. | Date: 2013-04-30

Disclosed is a method of operating an immediate value in an extendable instruction set computer (EISC) processor, comprising: checking whether or not an unsigned immediate value is used to generate an extension register (ER) value for operating an immediate value; and generating the ER value by performing zero extension for the unsigned immediate value using an unsigned load extension register with immediate (ULERI) instruction if the unsigned immediate value is used. It is possible to improve operational efficiency by preventing an LERI instruction from being unnecessarily executed when an immediate value is operated using a 16-bit instruction in the EISC processor.

Dongjin Semichem Co. and Korea University | Date: 2011-11-16

Disclosed is a novel organic dye containing trialkoxysilyl group and a method of preparing the same. The dye compound of the present invention has higher photovoltaic cell performance and more excellent stability than the existing dyes, and thus may be used for a dye-sensitized solar cell (DSSC) to largely improve solar cell efficiency.

Agency: Cordis | Branch: FP7 | Program: NOE | Phase: ICT-2009.1.5 | Award Amount: 4.09M | Year: 2010

3DLife will integrate leading European research groups to create a long-term integration of critical mass for innovation of currently fragmented research addressing media Internet. The main objective of the NoE are:\n\n-To foster the creation of sustainable relationships between existing national research groups and to start development of a Virtual Centre of Excellence in the field.\n\n-To create sufficient momentum by integrating an existing large number of researchers and resources and to push forward new paradigms on 3D media communication and interaction over the Internet.\n\n-To influence European and world research agenda in several key aspects of 3D Media Internet.\n\n3DLife aims at supporting the creation of a Virtual Center of Excellence in Media Internet and conduct cooperative research in the field. To achieve this goal 3DLife will integrate complementary expertise, enable resource optimization and sharing, and foster research in Media Internet technology.\n3DLife addresses wide, Pan-European integration through dedicated activities aiming at sharing laboratory facilities, technological developments and resources, including people. To ensure this wide cooperation and to guarantee that the targeted integrative research profits from, feeds back into, and fosters links with research groups of the 12 new EU member states, a Pan-European Integration Board will be part of the project. The technical and integration goals will be influenced by two other external and independent Boards of Industrial and Scientific Advisors.

Korea University and Dongjin Semichem Co. | Date: 2010-10-29

The present invention relates to an electric-field drive display device. According to one embodiment of the present invention, the electric-field drive display device comprises: a first substrate; a first electrode which is formed on the first substrate; a second electrode which is formed on the first substrate and is disposed in parallel with the first electrode; a drive partition wall which is formed on the first electrode and the second electrode and has a plurality of opening and closing holes; and a plurality of drive bodies which are disposed inside each of the opening and closing holes. Consequently, the electric-field drive display device according to one embodiment of the present invention can adjust the amount of light transmitted and so display the desired image by adjusting the positions of the drive bodies in the horizontal direction through the use of electrical force.

Hwang Y.H.,Armed Forces Capital Hospital | Yoo C.,Korea University | Kim Y.Y.,Korea University
Journal of Glaucoma | Year: 2012

Purpose: To investigate the correlation between myopic optic disc tilt and the characteristics of peripapillary retinal nerve fiber layer (RNFL) thickness measured by Cirrus HD spectral-domain optical coherence tomography (Cirrus HD OCT; Carl Zeiss Meditec, Dublin, CA). Methods: A total of 255 eyes of 255 healthy young male participants with various degrees of refractive errors (mean spherical equivalent, -3.17±2.40 D; range, -11.00 to 0.00 D) underwent ophthalmic examinations, including refractive error, axial length, and optic disc area measurement. The degree of horizontal/vertical optic disc tilt was evaluated by cross-sectional images obtained by the Cirrus HD OCT. The average, superior, nasal, inferior, and temporal quadrant thickness and superior/inferior peak locations of the peripapillary RNFL were also measured with the Cirrus HD OCT. Results: On the univariate analysis, eyes with more temporally tilted optic discs (horizontal tilt) had higher myopia, greater axial length, a thinner average, superior, nasal, and inferior RNFL, thicker temporal RNFL, and more temporally positioned superior/inferior peak locations (all P values <0.001). The degree of inferior optic disc tilt (vertical tilt) was associated with high myopia and a more temporally positioned inferior peak location (all P values <0.05). On multivariate analysis, eyes with more temporally tilted optic discs had a thicker temporal RNFL and more temporally positioned superior/inferior peak locations. Conclusions: The characteristics of the peripapillary RNFL thickness were associated with the degree of myopic optic disc tilt, especially in the temporal area. The degree of myopic optic disc tilt should be considered when interpreting the RNFL thickness measured by the Cirrus HD OCT. © 2012 by Lippincott Williams & Wilkins.

Kim H.J.,Korea University | Lee M.H.,Korea University | Mutihac L.,University of Bucharest | Vicens J.,French National Center for Scientific Research | Kim J.S.,Korea University
Chemical Society Reviews | Year: 2012

The present critical review reports on recent developments of optical nanoparticles based on the association of gold, silver, silica and quantum dots and calixarenes. These hybrid organic-inorganic compounds characterized by a thick organic layer self-assembled on the surface of a core of mineral surface atoms take advantage of the supramolecular recognition of luminescent calixarenes to fabricate nanodevices of nanoparticle size, capable of detecting metal cations, polyaromatic hydrocarbons and pesticides. Also presented is an explanation of the involvement of such nanoparticles in biochemical systems. This critical review provides an overview of their preparation, the manner in which they are characterized, and their use (108 references). © 2012 The Royal Society of Chemistry.

Jung H.S.,Korea University | Chen X.,Ewha Womans University | Chen X.,Nanjing University of Technology | Kim J.S.,Korea University | Yoon J.,Ewha Womans University
Chemical Society Reviews | Year: 2013

In the past few decades, the development of optical probes for thiols has attracted great attention because of the biological importance of the thiol-containing molecules such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). This tutorial review focuses on various thiol detection methods based on luminescent or colorimetric spectrophotometry published during the period 2010-2012. The discussion covers a diversity of sensing mechanisms such as Michael addition, cyclization with aldehydes, conjugate addition-cyclization, cleavage of sulfonamide and sulfonate esters, thiol-halogen nucleophilic substitution, disulfide exchange, native chemical ligation (NCL), metal complex-displace coordination, and nanomaterial-related and DNA-based chemosensors. This journal is © 2013 The Royal Society of Chemistry.

Truong P.L.,Sungkyunkwan University | Kim B.W.,Sungkyunkwan University | Sim S.J.,Korea University
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2012

We report a simple, ultra-sensitive, and straightforward method for non-labeling detection of a cancer biomarker, using Rayleigh light scattering spectroscopy of the individual nanosensor based on antibody-antigen recognition and localized surface plasmon resonance (LSPR) λ max shifts. By experimentally measuring the refractive index sensitivity of Au nanorods, the Au nanorod with an aspect ratio of ∼3.5 was proven optimal for the LSPR sensing. To reduce the steric hindrance effect as well as to immobilize a large amount of ligand on the nanoparticle surface, various mixtures containing different molar ratios of HS(CH 2) 11(OCH 2CH 2) 6OCH 2COOH and HS(CH 2) 11(OCH 2CH 2) 3OH were applied to form different self-assembled monolayer surfaces. The results showed that the best molar ratio for antibody conjugation was 1:10. When using individual Au nanorod sensors for the detection of prostate specific antigen (PSA), the lowest concentration recorded was ∼1 aM (∼6 × 10 5 molecules), corresponding to LSPR λ max shifts of ∼4.2 nm. These results indicate that sensor miniaturization down to the nanoscale level, the reduction of steric hindrance, and optimization of size, shape, and aspect ratio of nanorods have led to a significant improvement in the detection limit of sensors. © 2012 The Royal Society of Chemistry.

Zhang J.F.,Korea University | Zhang J.F.,Yunnan Normal University | Zhou Y.,Ewha Womans University | Yoon J.,Ewha Womans University | Kim J.S.,Korea University
Chemical Society Reviews | Year: 2011

Due to the wide range of applications and biological significance, the development of optical probes for silver, gold and platinum ions has been an active research area in the past few years. This tutorial review focuses on the recent contributions concerning the fluorescent or colorimetric sensors for these metal ions, and is organized according to their structural classifications (for Ag+ detection) and unique mechanisms between the sensors and metal ions (for Au3+ and Pt2+ detection). © 2011 The Royal Society of Chemistry.

Hewitt C.A.,Wake forest University | Kaiser A.B.,MacDiarmid Institute for Advanced Materials and Nanotechnology | Roth S.,Korea University | Craps M.,NanoTechLabs Inc. | And 2 more authors.
Nano Letters | Year: 2012

Thermoelectrics are materials capable of the solid-state conversion between thermal and electrical energy. Carbon nanotube/polymer composite thin films are known to exhibit thermoelectric effects, however, have a low figure of merit (ZT) of 0.02. In this work, we demonstrate individual composite films of multiwalled carbon nanotubes (MWNT)/polyvinylidene fluoride (PVDF) that are layered into multiple element modules that resemble a felt fabric. The thermoelectric voltage generated by these fabrics is the sum of contributions from each layer, resulting in increased power output. Since these fabrics have the potential to be cheaper, lighter, and more easily processed than the commonly used thermoelectric bismuth telluride, the overall performance of the fabric shows promise as a realistic alternative in a number of applications such as portable lightweight electronics. © 2012 American Chemical Society.

Truong P.L.,Sungkyunkwan University | Choi S.P.,Korea University | Sim S.J.,Korea University
Small | Year: 2013

A strategy for attomolar-level detection of small molecule-size proteins is reported based on Rayleigh light scattering spectroscopy of individual nanoplasmonic aptasensors by exploiting the outstanding characteristics of gold colloids to amplify the nontransparent resonant signal at ultralow analyte concentrations. The fabrication method utilizes thiol-mediated adsorption of a DNA aptamer on the immobilized Au nanoparticle surface, the interfacial binding characteristics of the aptamer with its target molecules, and the antibody-antigen interaction through plasmonic resonance coupling of the Au nanoparticles. Using lysozyme as a model analyte for disease detection, the detection limit of the aptasensor is ∼7 × 103 aM, corresponding to the LSPR λmax shift of ∼2.25 nm. Up to a 380% increase in the localized resonant λmax shift is demonstrated upon antibody binding to the analyte compared to the primary response during signal amplification using immunogold colloids. This enhancement leads to a limit of detection of ∼7 aM, which is an improvement of three orders of magnitude. The results demonstrate substantial promise for developing coupled plasmonic nanostructures for ultrasensitive detection of various biological and chemical analytes. An individual aptasensor is effectively exploited to detect disease utilizing thiol-mediated adsorption of the DNA aptamer, the interfacial binding characteristics of the aptamer with its target, and the antibody-antigen interaction through plasmon coupling of the nanoparticles. Up to a 380% increase in the LSPR λmax shift is demonstrated compared to an unenhanced shift using immunogold as the resonant label. This leads to a detection limit of ∼7 aM. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mutihac L.,University of Bucharest | Lee J.H.,Korea University | Kim J.S.,Korea University | Vicens J.,French National Center for Scientific Research
Chemical Society Reviews | Year: 2011

The calixarenic receptors exhibit remarkable host-guest properties towards biologically relevant guests. Aspects of complex formation reactions between both native and derivatized amino acids, di-and tripeptides with calixarenic (chiral or not) receptors are summarized in this critical review. Thus, the discussions emphasize the parameters that affect the molecular binding selectivity and efficiency of functionalized calix[n]arenes towards these substrates. A brief survey on their application in separation of amino acids is also considered (123 references). © 2011 The Royal Society of Chemistry.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: EeB.NMP.2012-5 | Award Amount: 6.83M | Year: 2012

Windows are critical elements to control the energy performance of buildings especially for zero-energy buildings. It is of paramount importance to develop windows which show reduced U-value, weight and costs and certain features to control and harvest energy. Such a window will have a high impact in the window industry and will reduce green house gas emissions as long as the window is affordable, can be used in renovation and in every climate zone. Therefore MEM4WIN is aiming at the following goals (1) weight reduction (2) energy control and harvesting (3) replacement of cost intensive processes and materials. (1) We will introduce a novel IG-Unit for quadruple glazing containing ultra thin glass membranes dedicated as frameless openable windows for direct application in facades. Due to this approach U-values of 0.3 W/mK can be achieved reducing weight by more than 50% and costs by 20%. (2) We will implement printed organic photovoltaics (OPVs) and solar thermal collectors for energy harvesting and micro mirrors for energy control and advances day lighting. (3) Fabrication costs will further be reduced by replacing conventional and cost intensive materials used for contacts like ITO and silver by graphene. We will introduce production methods like roll-to-plate and ink-jet printing to fabricate contacts for OPVs. At the end of the project the different components like micro mirrors, OPVs, organic light emitting diodes (OLEDs) and solar thermal collector will be integrated into a demonstrator showing the suitability of the used equipment, processes and new materials developed within MEM4WIN. Each aspect of MEM4WIN - (1) weight reduction, (2) energy control and harvesting, (3) replacement of cost intensive processes and materials - is represented by experts in this field resulting in a multidisciplinary highly motivated consortium containing participants from basic research as well as industrial endusers from whole Europe.

Kim H.N.,Ewha Womans University | Ren W.X.,Korea University | Kim J.S.,Korea University | Yoon J.,Ewha Womans University
Chemical Society Reviews | Year: 2012

Exposure to even very low levels of lead, cadmium, and mercury ions is known to cause neurological, reproductive, cardiovascular, and developmental disorders, which are more serious problems for children particularly. Accordingly, great efforts have been devoted to the development of fluorescent and colorimetric sensors, which can selectively detect lead, cadmium, and mercury ions. In this critical review, the fluorescent and colorimetric sensors are classified according to their receptors into several categories, including small molecule based sensors, calixarene based chemosensors, BODIPY based chemosensors, polymer based chemosensors, DNA functionalized sensing systems, protein based sensing systems and nanoparticle based sensing systems (197 references). © 2012 The Royal Society of Chemistry.

Chen X.,Ewha Womans University | Chen X.,Nanjing University of Technology | Pradhan T.,Korea University | Wang F.,Ewha Womans University | And 2 more authors.
Chemical Reviews | Year: 2012

Different xanthene derivatives according to their analytes with mechanistic schemes published from 1997 to February 2011 are introduced. Kim and co-workers reported the design and synthesis of a new rhodamine-based derivative, bearing an N-butyl-1,8-naphthalimide group. Huang's and Li's groups reported a rhodamine B derivative, containing a highly electron-rich S atom as a fluorescence turn-on chemodosimeter for Cu 2+ in an aqueous medium. Peng et al. reported a rhodamine-based chemodosimeter, via a mechanism of Hg 2+-promoted hydrolysis. Lin et al. presented a rhodamine-based probe, composed of a sulfur atom and an alkyne moiety for the irreversible detection of Hg 2+. Shang et al. synthesized molecule, composed of a fluorescein fluorophore and a rhodamine B hydrazide linked together by a thiourea spacer. Nagano and co-workers have synthesized a series of symmetric and asymmetric rhodamine derivatives,using rhodamine as scaffolds.

Bstieler L.,University of New Hampshire | Hemmert M.,Korea University
Journal of Product Innovation Management | Year: 2010

Despite the growing popularity of new product development across organizational boundaries, the processes, mechanisms, or dynamics that leverage performance in interorganizational (I-O) product development teams are not well understood. Such teams are staffed with individuals drawn from the partnering firms and are relied on to develop successful new products while at the same time enhancing mutual learning and reducing development time. However, these collaborations can encounter difficulties when partners from different corporate cultures and thought worlds must coordinate and depend on one another and often lead to disappointing performance. To facilitate collaboration, the creation of a safe, supportive, challenging, and engaging environment is particularly important for enabling productive collaborative I-O teamwork and is essential for learning and time efficient product development. This research develops and tests a model of proposed factors to increase both learning and time efficiency on I-O new product teams. It is argued that specific behaviors (caring), beliefs (psychological safety), task-related processes (shared problem solving), and governance mechanisms (clear management direction) create a positive climate that increases learning and time efficiency on I-O teams. Results of an empirical study of 50 collaborative new product development projects indicate that (1) shared problem solving and caring behavior support both learning and time efficiency on I-O teams, (2) team psychological safety is positively related to learning, (3) management direction is positively associated with time efficiency, and (4) shared problem solving is more strongly related to both performance dimensions than are the other factors. The factors supporting time efficiency are slightly different from those that foster learning. The relative importance of these factors also differs considerably for both performance aspects. Overall, this study contributes to a better understanding of the factors that facilitate a favorable environment for productive collaboration on I-O teams, which go beyond contracts or top-management supervision. Establishing such an environment can help to balance management concerns and promote the success of I-O teams. The significance of the results is elevated by the fragility of collaborative ventures and their potential for failure, when firms with different organizational cultures, thought worlds, objectives, and intentions increasingly decide to work across organizational boundaries for the development of new products. © 2010 Product Development and Management Association.

Zhao Q.,California Institute of Technology | Koch C.,California Institute of Technology | Koch C.,Korea University
Journal of Vision | Year: 2011

Inspired by the primate visual system, computational saliency models decompose visual input into a set of feature maps across spatial scales in a number of pre-specified channels. The outputs of these feature maps are summed to yield the final saliency map. Here we use a least square technique to learn the weights associated with these maps from subjects freely fixating natural scenes drawn from four recent eye-tracking data sets. Depending on the data set, the weights can be quite different, with the face and orientation channels usually more important than color and intensity channels. Inter-subject differences are negligible. We also model a bias toward fixating at the center of images and consider both time-varying and constant factors that contribute to this bias. To compensate for the inadequacy of the standard method to judge performance (area under the ROC curve), we use two other metrics to comprehensively assess performance. Although our model retains the basic structure of the standard saliency model, it outperforms several state-of-the-art saliency algorithms. Furthermore, the simple structure makes the results applicable to numerous studies in psychophysics and physiology and leads to an extremely easy implementation for real-world applications. © ARVO.

Hou X.,California Institute of Technology | Harel J.,California Institute of Technology | Koch C.,California Institute of Technology | Koch C.,Korea University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2012

We introduce a simple image descriptor referred to as the image signature. We show, within the theoretical framework of sparse signal mixing, that this quantity spatially approximates the foreground of an image. We experimentally investigate whether this approximate foreground overlaps with visually conspicuous image locations by developing a saliency algorithm based on the image signature. This saliency algorithm predicts human fixation points best among competitors on the Bruce and Tsotsos [1] benchmark data set and does so in much shorter running time. In a related experiment, we demonstrate with a change blindness data set that the distance between images induced by the image signature is closer to human perceptual distance than can be achieved using other saliency algorithms, pixel-wise, or GIST [2] descriptor methods. © 2012 IEEE.

Yong K.-T.,Nanyang Technological University | Law W.-C.,State University of New York at Buffalo | Hu R.,Nanyang Technological University | Ye L.,Chinese PLA General Hospital | And 4 more authors.
Chemical Society Reviews | Year: 2013

Tremendous research efforts have been devoted to fabricating high quality quantum dots (QDs) for applications in biology and medicine. Much of this research was pursued with an ultimate goal of using QDs in clinical applications. However, a great deal of concern has been voiced about the potential hazards of QDs due to their heavy-metal content. Many studies have demonstrated toxicity of various QDs in cell culture studies. However, in a smaller number of studies using small animal models (mice and rats), no abnormal behaviour or tissue damage was noticed over periods of months after the systemic administration of QDs. Nevertheless, the correlation of these results with the potential for negative effects of QD on humans remains unclear. Many urgent questions must be answered before the QDs community moves into the clinical research phase. This review provides an overview of the toxicity assessment of QDs, ranging from cell culture studies to animal models and discusses their findings. Guidelines for using various nonhuman primate models for QD toxicity studies are highlighted. This review article is intended to promote the awareness of current developments of QD applications in biology, the potential toxicity of QDs, and approaches to minimizing toxicity. © 2013 The Royal Society of Chemistry.

Jang M.J.,Korea University | Bang S.,Seoul National University | Oh D.,Korea University
Journal of Thrombosis and Haemostasis | Year: 2011

Background: Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), represents a major health concern in Caucasians. Although the incidence of VTE is generally known to be lower in Asians than in Caucasians, results of epidemiologic studies among Asians have been conflicting. In this study we performed a nationwide population-based epidemiologic study to provide basic information regarding the incidence of VTE in the Korean population. Methods: Using the Korean Health Insurance Review and Assessment Service (HIRA) database, VTE patients from 2004 to 2008 were retrospectively identified by both diagnostic codes and medication codes for drugs used in initial treatment of VTE. Results: The respective age- and sex-adjusted annual incidences of VTE, DVT and PE per 100 000 individuals increased significantly from 8.83, 3.91 and 3.74 in 2004 to 13.8, 5.31 and 7.01 in 2008 (P = 0.0001), with successive increments each year. All three annual incidences also increased steadily with age (P = 0.0001 for all), particularly among those over 60 years old. Conclusions: This represents the largest epidemiologic study that demonstrates a lower incidence of VTE in Asian compared with Western populations; however, it also demonstrates a yearly increasing incidence of VTE in the Korean population. © 2010 International Society on Thrombosis and Haemostasis.

Stoeger J.A.,University of Minnesota | Choi J.,Korea University | Tsapatsis M.,University of Minnesota
Energy and Environmental Science | Year: 2011

Continuous MFI-type zeolite membranes were fabricated on porous stainless steel tube supports by secondary (seeded) growth. The physical attachment of zeolite seed particles was initiated through sonication assistance on unmodified supports. Despite a sparse seed layer, a single hydrothermal growth step reliably led to c-/h0h-out-of-plane-oriented pure-silica MFI membranes. Rapid thermal processing was applied to as-synthesized membranes, extending the findings of a previous report on controlling the density of grain boundary defects. The RTP-treated membranes showed an improved separation factor of 29 for p-/o-xylene with a maximum p-xylene permeance of 6.6 × 10 -8 mol m -2 s -1 Pa -1, while conventionally (slowly) calcined counterparts had a maximum separation factor and p-xylene permeance of 3-4 and 2.7-4.5 × 10 -8 mol m -2 s -1 Pa -1, respectively. The membranes also showed insensitivity to temperature for n-/i-butane separation performance (separation factor ca. 15 and n-butane permeance ca. 1.3 × 10 -7 mol m -2 s -1 Pa -1), while conventionally calcined ones exhibited a significant decrease in the separation factor with temperature. Pervaporation measurements from a dilute aqueous feed that exploited the hydrophobicity of RTP-treated membranes revealed their potential use in bioalcohol recovery processes from fermentation broths, specifically for ethanol (total flux and separation factor of 1.2 kg m -2 h -1 and 43, respectively) and n-butanol (total flux and separation factor of 0.11 kg m -2 h -1 and 21, respectively) extraction from the aqueous phase. © 2011 The Royal Society of Chemistry.

Lim E.-K.,Yonsei University | Lim E.-K.,Korea Research Institute of Bioscience and Biotechnology | Kim T.,Korea University | Kim T.,Samsung | And 5 more authors.
Chemical Reviews | Year: 2015

Theranostics as a treatment strategy for individual patients encompasses a wide range of subjects, including personalized medicine, pharmacogenomics, and molecular imaging, in order to develop an efficient new targeted therapy and optimize drug selection via a better molecular understanding. Furthermore, theranostics aims to monitor the response to the treatment, to increase drug efficacy and safety, and to eliminate the unnecessary treatment of patients, resulting in significant cost savings for the overall healthcare system. Highly characteristic and nonrandom mutation patterns are found in well-studied oncogenes and tumor suppressor genes. Oncogenes are recurrently mutated at the same amino acid positions, leading to increased activity of the corresponding proteins.

Han J.-H.,Korea University | Kang J.U.,Johns Hopkins University
Applied Physics B: Lasers and Optics | Year: 2012

The effect of higher-order modes in fiber bundle imager-based optical coherence tomography (OCT) has been theoretically modeled using coupled fiber mode analysis ignoring the polarization and core size variation in order to visualize the pure effect of multimodal coupling of the imaging bundle. In this model, the optical imaging fiber couples several higher-order modes in addition to the fundamental one due to its high numerical aperture for achieving light confinement to the single core pixel. Those modes become evident in a distance domain using A-mode (depth) OCT based on a mirror sample experiment where multiple peaks are generated by the spatial convolution and coherence function of the light source. The distance between the peaks corresponding to each mode can be estimated by considering the effective indices of coupled (guided) modes obtained from numerically solving the fiber mode characteristics equations and the fiber length. The results have been compared for various types (fiber dimensions and wavelengths) and lengths of fibers, which have mode separation of 715 μm (1404 μm) and 764 μm (1527 μm) for the measurement and analysis, respectively in a 152.5 mm (305 mm)-long imaging fiber. © Springer-Verlag 2011.

Roh H.,Korea University | Reinhorn A.M.,State University of New York at Buffalo
Engineering Structures | Year: 2010

The maximum acceleration response of a simple yielding structure is proportional to its structural strength. Therefore, in order to reduce accelerations, the overall strength of the structure should be decreased while controlling possible resulting increases of displacements with supplemental damping. The use of "rocking columns", a type of double hinged gravity column, is suggested to reduce the strength of part of the lateral resisting system. A simplified analytical model of the columns represented by a moment-curvature relationship and a stiffness matrix, verified through experiments, is developed and implemented in the structural analysis program IDARC2D. The experimental study done on rocking concrete columns is briefly presented to show their global behavior and adjust the simplified model. For dynamic analysis, nonlinear stress zone approach and hysteretic models are also developed. A numerical study is conducted to demonstrate that story acceleration responses can be reduced compared to conventional structures, while the increased displacements are controlled using supplemental viscous dampers. A 1/3 scaled model structure, previously tested at the University at Buffalo, is used to evaluate the global seismic behavior of weakening alternatives modified using rocking columns and added viscous dampers. © 2010 Elsevier Ltd.

Cho J.,Seoul National University | Chang H.,Seoul National University | Kwon S.C.,Seoul National University | Kim B.,Seoul National University | And 5 more authors.
Cell | Year: 2012

LIN28 plays a critical role in developmental transition, glucose metabolism, and tumorigenesis. At the molecular level, LIN28 is known to repress maturation of let-7 microRNAs and enhance translation of certain mRNAs. In this study, we obtain a genome-wide view of the molecular function of LIN28A in mouse embryonic stem cells by carrying out RNA crosslinking-immunoprecipitation- sequencing (CLIP-seq) and ribosome footprinting. We find that, in addition to let-7 precursors, LIN28A binds to a large number of spliced mRNAs. LIN28A recognizes AAGNNG, AAGNG, and less frequently UGUG, which are located in the terminal loop of a small hairpin. LIN28A is localized to the periendoplasmic reticulum (ER) area and inhibits translation of mRNAs that are destined for the ER, reducing the synthesis of transmembrane proteins, ER or Golgi lumen proteins, and secretory proteins. Our study suggests a selective regulatory mechanism for ER-associated translation and reveals an unexpected role of LIN28A as a global suppressor of genes in the secretory pathway. © 2012 Elsevier Inc.

Korea University and Samsung | Date: 2011-09-09

A method and apparatus provide an Internet service in a mobile communication terminal. The method includes determining a user interest subject from user data existing within the mobile communication terminal, collecting service items through network access, determining a subject for each of the collected service items, determining relevance between the user interest subject and each of the service items, and recommending a service item according to the relevance.

Samsung and Korea University | Date: 2014-10-14

The MRI apparatus includes a data processor, which time-serially performs undersampling on MR signals respectively received by coil channels included in a radio frequency (RF) multi-coil to acquire undersampled K-t space data, and an image processor that acquires a time-space correlation coefficient, based on noise information of the coil channels, and restores pieces of unacquired line data from the undersampled K-t space data by using the time-space correlation coefficient to acquire restored K-t space data, thereby increasing an accuracy of the time-space correlation coefficient to improve a quality of an image.

Korea University and Samsung | Date: 2014-10-17

A magnetic resonance imaging (MRI) apparatus and method are provided. The MRI apparatus includes a first interpolator configured to generate a plurality of first interpolation data by performing calibration on a plurality of undersampled K-space data obtained from a plurality of channel coils in a radio frequency (RF) multi-coil, respectively, and a second interpolator configured to generate a plurality of second interpolation data by performing calibration on a plurality of filtered data obtained by filtering the first interpolation data using a plurality of high-pass filters.

Korea University and Samsung | Date: 2014-02-20

Embodiments of the invention provide a dielectric waveguide antenna including a dielectric waveguide transmitting a signal applied from a power feeder, a dielectric waveguide radiator radiating the signal transmitted from the dielectric waveguide to the air through a first aperture, and a matching unit formed in a portion of the dielectric waveguide and controlling a serial reactance and a parallel reactance to thereby perform impedance matching between the dielectric waveguide radiator and the air, in order to reduce reflection generated in the first aperture during the radiation of the signal through the first aperture. Reflection in the aperture is reduced through the matching unit having various structures, thereby making it possible to improve characteristics of the dielectric waveguide antenna.

Korea University and Samsung | Date: 2012-11-02

A surveillance system and method are provided. The surveillance system includes an audio processing device which extracts an audio feature of an audio signal, and determines whether an abnormal event has occurred in a monitoring region, based on the audio feature; a video processing device which extracts a foreground region from a video signal, and determines whether an abnormal event has occurred in the monitoring region, based on motion information of the foreground region; and a context awareness device which calculates an audio abnormal probability and a video abnormal probability by respectively accumulating results of abnormal event occurrence/non-occurrence determinations performed on audio signals and results of abnormal event occurrence/non-occurrence determinations performed on video signals for a certain period of time, and finally determines whether an abnormal situation has occurred in the monitoring region, by using respective combined probability distribution models for a normal situation and the abnormal situation.

Korea University, Electronics and Telecommunications Research Institute | Date: 2011-12-13

A digital forensic apparatus for analyzing user activities includes: a collection unit for collecting analysis information related to user activities from a device as an investigation target for analyzing the user activities; and an analysis unit for analyzing the analysis information collected by the collection unit to determine activity information of a user from each type of the analysis information, and for causing the activity information to be arranged and displayed in temporal order.

Korea University and Samsung | Date: 2013-04-25

An approach is provided for manufacturing a nanostructure. A first thin film including a first block copolymer is formed on a substrate. A guide pattern is formed on the first thin film. A second thin film including a second block copolymer is formed between portions of the guide pattern. The second thin film is cured. The first block copolymer is a cylinder-type and the second block copolymer is a lamella-type.

A method and apparatus for generating a magnetic resonance image including applying to a target first radio frequency (RF) pulses having phases and different frequencies to excite a plurality of sub-volumes constituting a volume of the target, and acquiring first magnetic resonance signals from the plurality of sub-volumes, and applying to the target second RF pulses having the same frequencies as the frequencies of the first RF pulses and phases at least one of which is different from the phases of the first RF pulses, and acquiring second magnetic resonance signals from the plurality of sub-volumes. Also, data may be generated based on the first and second magnetic resonance signals.

An apparatus and a method for transmitting data using a fountain code are provided. The method for transmitting data includes determining a degree distribution of a fountain code based on erasure rate information regarding at least one receiving end, performing fountain encoding according to the degree distribution, and transmitting symbols generated by the fountain encoding.

Korea University and Samsung | Date: 2013-01-09

An optical probe for irradiating light onto a subject includes an optical path control unit configured to receive light from outside the optical probe, and change a path of the light within the optical probe; an optical path length control element configured to receive the light having the changed path from the optical path control unit, and change an optical path length of the light as the optical path control unit changes the path of the light; and an optical output unit configured to receive the light having the changed optical path length from the optical path length control element, and output the light.

Samsung and Korea University | Date: 2015-02-17

Provided is an apparatus and method for connecting to an Access Point (AP) based on beacon information in a wireless communication system. To this end, a wireless device predicts an interference condition from each of a plurality of APs based on information acquired by a received beacon, selects one of the plurality of APs, taking the predicted interference condition into account, and attempts connection to the selected AP.

A method for operating a receiving portable terminal in a mobile communication system includes receiving a first packet from a sending portable terminal, determining a fingerprint overlapping a fingerprint corresponding to at least one chunk of the first packet in a fingerprint set cache, determining a fingerprint set including the most redundant fingerprints, in the fingerprint set cache, determining at least one fingerprint to send, in the determined fingerprint set, sending the at least one determined fingerprint to the sending portable terminal, and receiving a second packet from the sending portable terminal. An apparatus includes a controller configured to determine at least one redundant fingerprint overlapping a fingerprint corresponding to at least one chunk of the first packet in a fingerprint set cache, determine a fingerprint set including the most redundant fingerprint in the fingerprint set cache, and determine at least one fingerprint to send in the determined fingerprint set.

A method of inspecting the quality of an organic light-emitting diode (OLED) and an inspecting system for performing the method are disclosed. In one aspect, the method includes applying an input voltage to the OLED, measuring an OLED voltage across the OLED and an OLED current flowing through the OLED, estimating a parameter of the OLED based at least in part on the OLED voltage and the OLED current, and extracting a physical characteristic of the OLED based at least in part on the parameter.

Korea University and Samsung | Date: 2012-11-09

A method of generating a magnetic resonance image includes: generating pieces of first interpolation data by interpolating pieces of data obtained from each of the plurality of coils; generating pieces of weighted data by weighting the pieces of first interpolation data with respect to a plurality of frequency bands; and obtaining the magnetic resonance image corresponding to a subject by using the pieces of weighted data.

Samsung and Korea University | Date: 2010-10-15

Disclosed is a three-dimensional (3D) mesh compression apparatus and method. The 3D mesh compression apparatus may generate a base mesh through a mesh simplification, may separately compress the base mesh and peaks eliminated by the simplification, may construct a covariance matrix based on a topological distance between the eliminated peaks, and may compress 3D mesh data based on the covariance matrix.

A method of fabricating a nano resonator, includes forming a line pattern in a first substrate, and transferring the line pattern to a second substrate including a gate electrode. The method further includes forming a source electrode and a drain electrode on the transferred line pattern.

Samsung and Korea University | Date: 2014-10-07

Provided is a method and apparatus for controlling power in a wireless communication system. The method includes a transmitter transmits a signal to multiple receivers. The method also includes receiving a feedback signal including channel state information from each of the multiple receivers. The method also includes calculating a sum of received signal strengths of the feedback signal received from each of the multiple receivers. The method also includes determining a power control value by using the channel state information for each of the multiple receivers and the sum of the received signal strengths. The method also includes controlling a transmission power based on the determined power control value.

An apparatus and a method for interference cancellation in a Multiple Input Multiple Output (MIMO) wireless communication system. The method for interference cancellation includes equalizing first reception signals received through two or more reception antennas to estimate transmission signals transmitted through two or more transmission antennas, generating two or more second reception signals in which a mutual interference between the transmission signals is removed from the first reception signals by using the estimated transmission signals, independently equalizing the generated two or more second reception signals, and combining the independently equalized two or more second reception signals to estimate a transmission signal in which an interference is removed.

Korea University and Samsung | Date: 2012-11-09

A method of generating a magnetic resonance image includes: generating composite data by using a plurality of data sets acquired from a plurality of coils, based on coil characteristics of the plurality of coils; generating first interpolation data by interpolating the composite data; generating a plurality of filtered data sets by filtering the first interpolation data with respect to a plurality of frequency bands; and generating the magnetic resonance image by using the plurality of filtered data sets.

Korea University and Samsung | Date: 2011-06-30

A detergent case includes a remaining water discharge hole formed on a bottom surface of a liquid detergent accommodation space, and an opening and closing unit to open and close the remaining water discharge hole due to buoyancy of a liquid accommodated within the liquid detergent accommodation space.

A method of avoiding channel interference in a multi-channel sensor network, includes periodically measuring an energy of a channel used by at least one node included in the sensor network; determining if the energy of the channel has a value larger than a first preset threshold; when the energy of the channel has a value larger than the first preset threshold, concluding that the channel is influenced by an interference from an interference source, and reporting it to a parent node of the at least one node; and switching the channel influenced by the interference to a new channel, which is not influenced by an interference, thereby avoiding an influence of the interference.

Disclosed are a method and an apparatus for grouping antennas in a multiple-input multiple-output antenna system. The method of the present invention comprises the steps of: measuring a channel vector for a plurality of antennas of a base station; grouping channel coefficients of the channel vector in accordance with a plurality of antenna grouping patterns and determining grouped codebook vectors corresponding to the grouped channel coefficients; selecting one of the antenna grouping patterns using the grouped codebook vectors for the antenna grouping patterns; and feeding back, to the base station, a pattern index indicating the selected antenna grouping pattern and a codebook index indicating the grouped codebook vector corresponding to the selected antenna grouping pattern.

Samsung and Korea University | Date: 2011-02-08

A method of generating a 3D complex octree map. A plurality of points each having 3D location information are detected from a range image. A space having the detected plurality of points is represented using grids. If points in a grid forms a plane, the grid is not subdivided and planar information about the plane is stored. A space not forming a plane is subdivided, thereby enhancing the storage efficiency.

Korea University and Samsung | Date: 2012-07-24

A data transmission system transmitting data using a relay is provided. The relay selects a transmission terminal from a plurality of terminals connected to a base station. During a first time slot, the base station transmits base station data to the relay and the transmission terminal transmits terminal data to the relay. The relay transmits the terminal data to the base station and transmits the base station data to the transmission terminal during a second time slot.

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