Korea Army Academy at Yeong Cheon

South Korea

Korea Army Academy at Yeong Cheon

South Korea

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Kim D.,Korea Army Academy at Yeong cheon | Yoo J.H.,University of Texas at Dallas | Lee J.-B.,University of Texas at Dallas
Journal of Micromechanics and Microengineering | Year: 2016

Conventional ultraviolet (UV) lithography typically uses a photomask made of a fused silica plate covered with a layer of UV opaque material such as chromium. The photomask has passive binary patterns of UV opaque and UV transparent regions and the pattern is unalterable. We report a novel real-time dynamically reconfigurable photomask technology using a liquid metal (as a UV opaque material) filled in polydimethylsiloxane (PDMS, as a UV transparent material) microfluidic channels. We found that the gallium-based liquid metal (e.g. Galinstan®) is opaque in broad spectrum of light in the wavelength from 325 nm to 850 nm while the PDMS is highly transparent in this wide range of spectrum. We made both bright field and dark field microfluidic photomasks and transferred various patterns onto a positive photoresist. A 7-segment display microfluidic channel photomask was also fabricated and decimal numerals (from '0' to '9') were patterned with one photomask by dynamically reconfiguring decimal numeral shapes with on-demand injection and withdrawal of the liquid metal in specific segment microfluidic channels in the photomask. In addition, utilizing mechanical flexibility of the PDMS and the liquid metal, reconfiguration of the patterns in a microfluidic photomask under stretching was successfully tested. © 2016 IOP Publishing Ltd.


Kim D.-H.,Korea Army Academy at Yeong Cheon | Jo S.-U.,Eco Phile Co. | Yoo J.-C.,Chonbuk National University | Baek K.,Chonbuk National University
Separation and Purification Technology | Year: 2013

This study was conducted to investigate electrokinetic removal of salts from saline soil with reduced electrical energy consumption using pulsed current that periodically repeats on/off using a direct current (DC) power supply in a pilot scale system (15 min on and off periodically). Each experiment was operated with a constant voltage gradient of 1 V/cm in a reactor (1 × 1 × 0.18 m) using real saline soil during 9 weeks. The removal efficiency of anions in the conventional DC system was slightly higher than that of the pulse system. However, there was less of a difference in removal efficiency between the conventional DC and pulse systems, except with NO3-. The removal efficiency of cations in the conventional DC system was higher than that of the pulse system, which is beneficial for cultivation because cations such as Na +, Mg2+ and K+ are essential elements for crop growth. Even though the pulsed current removed slightly fewer salts and less electrical conductivity than conventional power, the system lowered the electrical energy consumption to 64% and effectively prevented pH changes and electrode corrosion compared with conventional power. Therefore, pulsed current could be an effective technique for electrokinetic restoration of saline soil. © 2013 Elsevier B.V. All rights reserved.


Lim J.,KAIST | Doo S.,Korea Army Academy at Yeong cheon | Yoon H.,KAIST
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2013

In this paper, we suggested novel schemes which use advanced adaptive cluster transformation and VM selection policy for intrusion tolerant systems (ITSs). The cluster size is transformed adaptively in order to maintain a certain level of services by using the adaptive cluster expansion scheme. Also, all the servers in clusters can be substituted in case serious threat such as massive packets incoming is expected by using the adaptive cluster substitution method. If there exists reliable historical data, more fast transformation is possible. In addition, the less-vulnerable virtual machines (VMs) are chosen using evaluation policies to reduce data leakage occured from system's vulnerabilities. Simulation results done with CSIM 20 prove that the suggested schemes improve intrusion tolerance efficiently compared to other conventional methods. © 2013 IEEE.


Cusick T.W.,State University of New York at Buffalo | Cheon Y.,Korea Army Academy at Yeong Cheon
Designs, Codes, and Cryptography | Year: 2012

Rotation symmetric Boolean functions have been extensively studied in the last 10 years or so because of their importance in cryptography and coding theory. Until recently, very little was known about the basic question of when two such functions are affine equivalent. Even the case of quadratic functions is nontrivial, and this was only completely settled in a 2009 paper of Kim, Park and Hahn. The much more complicated case of cubic functions was solved for permutations using a new concept of patterns in a 2010 paper of Cusick, and it is conjectured that, as in the quadratic case, this solution actually applies for all affine transformations. The patterns method enables a detailed analysis of the affine equivalence classes for various special classes of cubic rotation symmetric functions in n variables. Here the case of functions with 2 k variables (this number is especially relevant in computer applications) and generated by a single monomial is examined in detail, and in particular a formula for the number of classes is proved. © Springer Science+Business Media, LLC 2011.


Cusick T.W.,State University of New York at Buffalo | Cheon Y.,Korea Army Academy at Yeong Cheon
Journal of Mathematical Cryptology | Year: 2015

Rotation symmetric Boolean functions have been extensively studied in the last 15 years or so because of their importance in cryptography and coding theory. Until recently, very little was known about such basic questions as when two such functions are affine equivalent. This question in important in applications, because almost all important properties of Boolean functions (such as Hamming weight, nonlinearity, etc.) are affine invariants, so when searching a set for functions with useful properties, it suffices to consider just one function in each equivalence class. This can greatly reduce computation time. Even for quadratic functions, the analysis of affine equivalence was only completed in 2009. The much more complicated case of cubic functions was completed in the special case of affine equivalence under permutations for monomial rotation symmetric functions in two papers from 2011 and 2014. There has also been recent progress for some special cases for functions of degree >3. In 2007 it was found that functions satisfying a new notion of k-rotation symmetry for k > 1 (where the case k = 1 is ordinary rotation symmetry) were of substantial interest in cryptography and coding theory. Since then several researchers have used these functions for k = 2 and 3 to study such topics as construction of bent functions, nonlinearity and covering radii of various codes. In this paper we develop a detailed theory for the monomial 3-rotation symmetric cubic functions, extending earlier work for the case k = 2 of these functions. © 2015 by De Gruyter 2015.


Chung J.,Samsung | Rittmann B.E.,Arizona State University | Her N.,Korea Army Academy at Yeong Cheon | Lee S.-H.,Hongik University | Yoon Y.,University of South Carolina
Water, Air, and Soil Pollution | Year: 2010

A new hybrid process has been proposed and evaluated the feasibility for complete removal of chromate and selenate at high level. The process consists of a H2-based membrane biofilm reactor (MBfR) and reverse osmosis (RO)/nanofiltration (NF) stages. The essential feature of the process is the recycling of the RO and NF concentrate into the membrane biofilm reactor. First, two different H2-based denitrifying MBfR initially reduced selenate (Se (VI)) or chromate (Cr (III)) stably to Se° or Cr (III) to limited levels (approximately 70-85% removal for selenate and approximately 40-65% removal for chromate). In order to achieve more stable and lower levels, two different membrane (NF and RO) filtration technologies as sequential process were combined. Two wastewaters produced from two MBfRs having similar amounts of target toxic ions (C o = 366 μg-Cr L-1 and C o = 326 μg-Se L-1), pH, and conductivity were tested to determine the solute rejection and the membrane flux for one RO and one NF membranes at varying recovery conditions (10-90%). The results show that the rejection of solutes decreases with increasing the recovery due to the increase in osmotic pressure. The rejections by the RO membrane were >99-98% for chromate and 99-94% for selenate, while slightly lower rejections (<20%) were observed for the NF membrane at the recovery conditions. © 2009 Springer Science+Business Media B.V.


Kim D.-H.,Korea Army Academy at Yeong Cheon | Yoon Y.,University of South Carolina | Baek K.,Chonbuk National University | Han J.,Korea Army Academy at Yeong Cheon | Her N.,Korea Army Academy at Yeong Cheon
Environmental Science and Pollution Research | Year: 2014

Perchlorate concentrations in rice samples from many different provinces, and correlation with surface water contamination, were investigated in the Republic of Korea. Perchlorate levels in the 51 rice samples purchased from local markets ranged from below the detection limit to 1.79 ± 0.39 μg/kg with a mean level of 0.21 μg/kg and 7 samples collected from the Nakdong River watershed ranged from 0.38 ± 0.1 to 3.23 ± 0.47 μg/kg with a mean level of 0.9 μg/kg. The correlation coefficient between perchlorate levels in rice samples from the Nakdong river watershed and the levels in surface water was estimated to be approximately 0.904 in the 95 % confidence interval. These results show that surface water contamination was highly related to the perchlorate pollution of rice in the Republic of Korea. © 2013 Springer-Verlag Berlin Heidelberg.


Kim W.,Texas A&M University | Kim W.,Korea Army Academy at Yeong cheon | Reddy J.N.,Texas A&M University
Latin American Journal of Solids and Structures | Year: 2010

on In this study, mixed finite element models of plate bending are developed to include other variables (e.g., the membrane forces and shear forces) in addition to the generalized displacements to investigate their effect nonlinear response. Various finite element models are developed using the weighted-residual statements of suitable equations. The classical plate theory and the first-order shear deformation plate theory are used in this study and the von Karman nonlinear strains are accounted for. Each newly developed model is examined and compared with displacement finite element models to evaluate their performance. Numerical results show that the new mixed models developed herein show better accuracy than existing displacement based models.


Kim D.-H.,Korea Army Academy at Yeong Cheon | Yoo J.-C.,Chonbuk National University | Hwang B.-R.,Chonbuk National University | Yang J.-S.,Korea Institute of Science and Technology | Baek K.,Chonbuk National University
Environmental Science and Pollution Research | Year: 2014

In this study, an environmental assessment on an electrokinetic (EK) system for the remediation of a multimetal-contaminated real site was conducted using a green and sustainable remediation (GSR) tool. The entire EK process was classified into major four phases consisting of remedial investigations (RIs), remedial action construction (RAC), remedial action operation (RAO), and long-term monitoring (LTM) for environmental assessment. The environmental footprints, including greenhouse gas (GHG) emissions, total energy used, air emissions of criteria pollutants, such as NOx, SOx, and PM10, and water consumption, were calculated, and the relative contribution in each phase was analyzed in the environmental assessment. In the RAC phase, the relative contribution of the GHG emissions, total energy used, and PM10 emissions were 77.3, 67.6, and 70.4 %, respectively, which were higher than those of the other phases because the material consumption and equipment used for system construction were high. In the RAO phase, the relative contributions of water consumption and NOx and SOx emissions were 94.7, 85.2, and 91.0 %, respectively, which were higher than those of the other phases, because the water and electricity consumption required for system operation was high. In the RIs and LTM phases, the environmental footprints were negligible because the material and energy consumption was less. In conclusion, the consumable materials and electrical energy consumption might be very important for GSR in the EK remediation process, because the production of consumable materials and electrical energy consumption highly affects the GHG emissions, total energy used, and air emissions such as NOx and SOx. © 2014 Springer-Verlag Berlin Heidelberg.


Kim D.,Korea Army Academy at Yeong Cheon | Choi J.,Kyung Hee University
Chemical Physics Letters | Year: 2011

This study shows another way to enhance the photoresponse of a conjugated polymer. This is confirmed by the wavelength and voltage-dependent photocurrent study of an anisotropic freestanding polymeric solid-state bridge, which was made of sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] between aluminum and copper wire electrodes. The field gradient induced by the anisotropic structure of the microscale polymer bridge enhanced the photoresponse by driving the photogenerated excitons toward the maximum field gradient region of the conical polymer bridge. The relatively high electric field strength at the narrow region efficiently broke excitons into electrons and holes. As a result, the photoresponse was enhanced. © 2010 Elsevier B.V. All rights reserved.

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