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BPS limit of multi- D- and DF-strings in boundary string field theory
Go, G.,Ishida, A.,Kim, Y. North-Holland Pub. Co 2007 Physics letters. Section B Vol.651 No.5-6
A BPS limit is systematically derived for straight multi- D- and DF-strings from the D3D@?3 system in the context of boundary superstring field theory. The BPS limit is obtained in the limit of thin D(F)-strings, where the Bogomolny equation supports singular static multi-D(F)-string solutions. For the BPS multi-string configurations with arbitrary separations, BPS sum rule is fulfilled under a Gaussian type tachyon potential and reproduces exactly the descent relation. For the DF-strings ((p,q)-strings), the distribution of fundamental string charge density coincides with its energy density and the Hamiltonian density takes the BPS formula of square-root form.
박수곡 ( Su Gog Park ),유경열 ( Kyeong-yeol Yu ),전철구 ( Cheol-koo Jeon ),남찬희 ( Chan Hui Nam ),박재범 ( Jae-beom Park ) 국군의무사령부 2013 대한군진의학학술지 Vol.44 No.1
Objectives : This study was designed to examine the state of health of workers and the exposure conditions of Volatile Organic Compounds and to improve the work conditions in oil laboratories. Method : We examined 22 workers in 9 oil laboratories. We measured the working environment and investigated biological indices. We checked the symptoms of workers and compared them with the reference group using a posturographic study. results : 9 materials of organic compounds were detected through working environment measurement. Toluene exceeded exposure level in one oil laboratory, but biological index was normal. The workers complained non-specific symptoms like headache, dizziness and nausea. There was no statistically significance to the reference group by posturographic study. Conclusion : We should measure the environment of work place and check the special medical examination in oil laboratory workers annually. Oil laboratories should adopt rule to improve work places conditions.
NCS 기반 국가기술자격 정보기기운용 직종 발전방안(정보기기운용기능사)에 관한 연구
하창국(Ha, Chang Gog),이민주(Lee, Min Ju) 한국IT서비스학회 2015 한국IT서비스학회 학술대회 논문집 Vol.2015 No.추계
NCS (National Competency System) 는 1 자격 종목의 미션과 비젼에 따른 취업증대 2.학습범위 최적화에 따른 실력중심사회구현 3.현장업무수준 체계에 따른 산업현장 체계화 4. 실습범위 실용화를 위한 신 자격 체계 구축 5. 취업 및 단계별 자격 직종 전문화에 따른 자기 발전 체계 구축으로 제안되어 반영한 것으로 압축 할 수 있을 것이다. 정보기기운용기능사 의 운용 고도화 목표는 이러한 “학력 중심이 아닌 실력 중심의 사회 구현”을 위한 NCS (National Competency System)를 기반으로 신 자격체계 업무 고도화를 지속적으로 행하는 것을 의미한다고도 할 수 있겠다. 이러한 NCS (National Competency System) 5대 목표를 체계적으로 구축하기 위하여 현재 산업 현장에서 네트워크 산업이 지속적으로 확대, 고도화 되어지는 추세에 맞추어 라우터 및 스위칭 장비 구성 및 운영에서 Security, 보이스접근, 네트워크 관리, LAN ATM 서비스 발생할 수 있는 문제 해결 방안등을 실기시험에 추가 확대하여 정보 기기운용 기능사가 명실공히 실무형 중심 자격직종으로 발전되어질 수 있도록 제안하고자 한다 이를 위하여 NCS 신 자격체계인 유선통신 운용사 L3 자격의 능력단위에서 「초고속망 서비스의 경로상태확인, 경로 트래픽 분석, IP주소자원관리, 우회경로 설정 항목」은 정보기기운용기능사 작업형 실기시험 출제기 준과 매우 일치하고 있어 향후 기존 검정형 자격을 폐지하고 유선통신운용사 L3 자격으로 대체하여 신 자격 체계 제도를 시행할 수 있도록 자격 종목 적용을 제안한다. 다만 이러한 실력 중심에 맞는 정보기기운용 자격직종의 발전방향의 개선 건의 사항으로는 실질적인 현장성 있는 네트워크 전문자격으로 발전 하기 위한 전제 조건으로 숙련된 출제·
Performance Modeling and Analysis of ATM-based Network System Using DEVS Methodology
Lee, Kyon-Ho,Kim, Tag-Gog,Lee, Joon-Won The Korea Institute of Information and Commucation 1999 韓國通信學會論文誌 Vol.24 No.7
DEVSim++ is a C++ based, object-oriented modeling/simulation environment which realizes the hierarchical, modular DEVS formalism for discrete event systems specification. The paper describes a methodology for performance modeling and analysis of an ATM-based network system within the DEVSim++ environment. The methodology develops performance models for the system using the DEVS framework and implement the models in C++. Performance indices measured are the length of queues located at connection of the system and cell waiting times with respect to QoS grades for a network bandwidth of 155 Mbps.
Youn Goo Kim,Avis, Christophe,Hye Rim Hwang,Tae Woong Kim,Young Gog Seol,Jin Jang IEEE 2014 Journal of display technology Vol.10 No.11
<P>We fabricated bottom-gate, bottom-contact oxide thin-film transistors (TFTs) using solution-processed strontium -doped zinc-tin-oxide (SrZTO) as the active material and high-κ aluminum oxide (AlOx) gate insulator at the maximum process temperature of 300 °C. The effect of Sr content on the device performance of the SrZTO TFTs was investigated, where Sr was changed from 0 to 20%. With increasing Sr concentration, threshold voltage shifted to the positive voltage, since the incorporation of Sr reduces the density of oxygen vacancy in ZTO. The mobility increases and threshold voltage shift to positive voltage with increasing Sr, and a 5% Sr doped ZTO transistor with AlOx gate insulator exhibited the field effect mobility of 7.82 cm<SUP>2</SUP>/V·s, subthreshold swing of 121 mV/dec, and threshold voltage of 0.71 V. It is found that the threshold voltage shifts by negative bias illumination stress decrease with increasing Sr.</P>
CNT/ABS/SAN계의 분산성에 미치는 MWNT Wrapping 전처리 효과
김성태 ( Sung Tae Kim ),박해윤 ( Hae Youn Park ),노태경 ( Tae Kyeong No ),강동국 ( Dong Gog Kang ),전일련 ( Ii Ryeon Jeon ),서관호 ( Kwan Ho Seo ) 한국공업화학회 2012 공업화학 Vol.23 No.4
탄소나노튜브는 좋은 전기 기계적 및 열적 특성을 가진 복합 재료 분야에서 가장 이상적인 나노 충전재이다. 따라서 탄소나노튜브의 복합 재료는 전도성 재료, 고강도를 가지면서 가벼운 무게를 가지는 재료에 이용된다. 탄소나노튜브 복합재료의 주요 문제점은 탄소나노튜브의 나쁜 분산에 있다. 본 연구에서는 다중벽 탄소나노튜브(MWNT)를 물리적 방법으로 전처리하였다. 전처리 후, 고분자/MWNT nanocomposites는 용해 공정에 의해 분산되었다. 물리적 방법은 고 분자 wrapping 방법에 의해 준비되었다. ABS/MWNT 복합 재료의 기계적 및 전기적 특성을 SAN과 함께 wrapping된 MWNT와 미처리된 MWNT와 혼합된 ABS의 속성을 비교하여 연구하였다. MWNT가 wrapping된 복합체의 인장강도는 증가하였으나 충격강도는 감소한 수치를 보였다. 전기적 물성의 향상에는 미처리시료와 비교해 볼 때 큰 효과가 없었다. Carbon nanotubes (CNT) are considered as one of ideal nano-fillers in the field of composites with their excellent electrical, mechanical, and thermal properties. Therefore CNT composites are increasingly used in fabricating conductive materials, structural materials with high strength and low weight, and multifunctional materials. The main problem of the CNT composites is difficulty in the dispersion of CNT in the polymer matrix. In this study multi-walled carbon nanotubes (MWNT) were pretreated by the physical process utilizing a wrapping method. After the pretreatment polymer/MWNT nanocomposites were prepared by melt processing. The effect of functionalization MWNT by wrapping with styrene acrylonitrile (SAN) on the mechanical and electrical properties of acrylonitrile butadiene styrene resin (ABS)/MWNT composites was studied by comparing the properties of ABS mixed with the neat MWNT. Electrical and mechanical properties of ABS/MWNT nanocomposites were studied as a function of the functionalization and content of MWNT. The tensile strength of the ABS/MWNT nanocomposites increased, but the impact strength decreased. The polymer wrapping in ABS system has little effect on the improvement of electrical properties.
Hozoi, L.,Gretarsson, H.,Clancy, J. P.,Jeon, B.-G.,Lee, B.,Kim, K. H.,Yushankhai, V.,Fulde, Peter,Casa, D.,Gog, T.,Kim, Jungho,Said, A. H.,Upton, M. H.,Kim, Young-June,van den Brink, Jeroen American Physical Society 2014 Physical review. B, Condensed matter and materials Vol.89 No.11
In the search for topological phases in correlated electron systems, materials with 5d transition-metal ions, in particular the iridium-based pyrochlores A2Ir2O7, provide fertile grounds. Several topological states have been predicted but the actual realization of such states is believed to critically depend on the strength of local potentials arising from distortions of the IrO6 cages. We test this hypothesis by measuring with resonant inelastic x-ray scattering the electronic level splittings in the A = Y, Eu systems, which we show to agree very well with ab initio quantum chemistry electronic-structure calculations for the series of materials with A = Sm, Eu, Lu, and Y. We find, however, that the primary source for quenching the spin-orbit interaction is not a distortion of the IrO6 octahedra but longer-range lattice anisotropies which inevitably break the local cubic symmetry.