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정서현(Seo-hyun Jeong),이성주(Sung-ju Lee),정용화(Youngwha Chung),김상춘(Sang-chun Kim),민병기(Byoung-ki Min) 한국정보보호학회 2011 정보보호학회논문지 Vol.21 No.3
모바일 응용에서 MPEG 비디오 스트림 등 대용량 데이터의 이용이 증가함에 따라, 전송되는 대용량 데이터의 정보보호가 중요한 문제로 부각되고 있다. 대용량 데이터의 효과적인 보호를 위한 부분 암호화 방법으로 SECMPEG이 존재한다. 그러나 SECMPEG의 보안 레벨 3은 B- 나 P-프레임에 비해 상대적으로 용량이 큰 I-프레임을 모두 암호화하기 때문에, 모바일 응용에 적용하기에는 암호화 오버헤드가 크다는 문제가 있다. 그러므로 MPEG2 표준의 압축 특성을 분석하여 I-프레임에서의 부분 암호화를 효과적으로 적용할 필요가 있다. 본 논문에서는 수신단에서 I-프레임 내의 에러 전파 특성을 이용하는, 슬라이스 레벨에서의 부분 암호화 방법을 제안한다. 실험 결과를 통하여 SECMPEG 보안 레벨 3과 비교하여 제안 방법은 보안 성능의 저하없이 수행 시간을 약 30배 이상 단축함을 확인하였다. According to increased multimedia data(i.e., MPEG video stream) in mobile application, protecting data becomes an important problem in the multimedia data delivery. SECMPEG is a selective encryption approach for protecting multimedia data. However, the computational overhead of SECMPEG's security level 3 is quite large because it encrypts the whole I-frames whose size is relatively larger than P/B-frames. Therefore, we need to analyze the characteristics of MPEG2 standard and derive an effective encryption of the I-frames. In this paper, we propose a slice-level, selective encryption approach by using the error-propagation characteristics of I-frames by a receiver. Our experimental results show that the proposed approach can reduce the execution time of SECMPEG's security level 3 by a factor of 30 without degradation of the security.
Reg. Guide 1.52(Rev.3)를 적용한 원전 ESF 공기정화계통 성능시험법 개선 연구
이숙경,김광신,손순환,송규민,이계우,박정서,조병호,유병재,홍순준,강선행,Lee, Sook-Kyung,Kim, Kwang-Sin,Sohn, Soon-Hwan,Song, Kyu-Min,Lee, Kae-Woo,Park, Jeong-Seo,Cho, Byoung-Ho,Yoo, Byeang-Jea,Hong, Soon-Joon,Kang, Sun-Haeng 한국방사성폐기물학회 2010 방사성폐기물학회지 Vol.8 No.4
U. S. NRC Regulation Guide 1.52 regulating ESF ACS in nuclear power plants has been revised to revision 3. To apply reduction of operability test time, allowance of alternative challenge agents for in-place leak test of HEPA filters, and upgrade of Methyl Iodide penetration acceptance criterion in activated carbon performance test suggested in Reg. Guide 1.52(Rev.3) on Yonggwang units 5 and 6 ESF ACSes, technical feasibility study was carried out with on-site experiments as well as experiments with a lab-scale model. It was confirmed that the moisture in the system returned to the level before the test in 1 or 4 days even though the moisture was removed during the operability test lasting more than 10 hours. Therefore, it is appropriate to perform monthly operability test in 15 minutes just long enough to check the operability of equipment. To change challenge material for in-place HEPA filter leak test, size of aerosol, production rate, and leak detection capability were compared for DOP and PAO. It was concluded that PAO can be substituted for DOP in nuclear power plants. The upgrade of Methyl Iodide penetration acceptance criterion from 0.175 % to 0.5 % in active carbon filter bed deeper than 4 inches was to conform to the change of activated carbon performance test method to ASTM D3803(1989). It was confirmed that Methyl Iodide penetration acceptance criterion of 0.5 % under $30^{\circ}C$, relative humidity 95 % condition was conservatively good enough for testing performance of active carbon insitu. The licence change of Yonggwang units 5 and 6 has been completed based on this study.
원자력등급 ESF 공기정화계통 시뮬레이터 제작 및 활용에 관한 연구
이숙경,김광신,손순환,송규민,이계우,박정서,홍순준,강선행,Lee, Sook-Kyung,Kim, Kwang-Sin,Sohn, Soon-Hwan,Song, Kyu-Min,Lee, Kei-Woo,Park, Jeong-Seo,Hong, Soon-Joon,Kang, Sun-Haeng 한국방사성폐기물학회 2010 방사성폐기물학회지 Vol.8 No.4
A nuclear plant ESF ACS simulator was designed, built, and verified to perform experiment related to ESF ACS of nuclear power plants. The dimension of 3D CAD model was based on drawings of the main control room(MCR) of Yonggwang units 5 and 6. The CFD analysis was performed based on the measurement of the actual flow rate of ESF ACS. The air flowing in ACS was assumed to have $30^{\circ}C$ and uniform flow. The flow rate across the HEPA filter was estimated to be 1.83 m/s based on the MCR ACS flow rate of 12,986 CFM and HEPA filter area of 9 filters having effective area of $610{\times}610mm^2$ each. When MCR ACS was modeled, air flow blocking filter frames were considered for better simulation of the real ACS. In CFD analysis, the air flow rate in the lower part of the active carbon adsorber was simulated separately at higher than 7 m/s to reflect the measured value of 8 m/s. Through the CFD analyses of the ACSes of fuel building emergency ventilation system, emergency core cooling system equipment room ventilation cleanup system, it was confirmed that all three EFS ACSes can be simulated by controlling the flow rate of the simulator. After the CFD analysis, the simulator was built in nuclear grade and its reliability was verified through air flow distribution tests before it was used in main tests. The verification result showed that distribution of the internal flow was uniform except near the filter frames when medium filter was installed. The simulator was used in the tests to confirm the revised contents in Reg. Guide 1.52 (Rev. 3).
도시고속도로의 진입연결로 접속부내 선형의 밀도예측모형 구축에 관한 연구
김태곤(Kim Tae Gon),신광식(Shin Kwang Sik),김승길(Kim Seung Gil),김정서(Kim Jeong Seo) 대한토목학회 2006 대한토목학회논문집 D Vol.26 No.1D
이 연구는 도시고속도로의 진입연결로 접속부내 선형의 밀도예측모형 구축에 관한 연구로서 실시간 교통특성분석과 선형의 밀도예측모형 구축 및 검증을 통해 밀도예측모형 구축에 있어서 결정계수(R²)값이 대체적으로 0.7이상으로 나타나 선형회귀모형구축에 상당히 높은 설명력을 보이는 것으로 나타났고, 선형모형검증에 있어서 상관계수(r)값도 대체적으로 0.8 이상으로 상당히 높은 상관성을 보이는 것으로 나타났다. 따라서 향후 선형의 밀도예측모형을 이용하여 도시고속도로의 진입연결로 접속부내 차량의 밀도추정 및 지체분석에 상당히 유효할 것으로 판단된다. This study was to construct the linear density predictive models on the on-ramp junctions in urban freeway. From the analyses of the real-time traffic characteristic data, and the construction and verification of the linear density predictive models, the models showed a considerable explanatory power with the determination coefficients (R²) of over 0.7 between the density and speed data. Also, they showed a considerably high correlativeness with the correlation coefficients (r) of over 0.8 between the calculated density data and the expected ones estimated by the models.
허신,구정서,우창수,김유일,Heo, Sin,Gu, Jeong-Seo,U, Chang-Su,Kim, Yu-Il 한국기계연구원 1996 硏究論文集 Vol.26 No.-
In this study, we performed the static analysis of a cord-reinforced rubber airspring and generated the three-dimensional half-symmetry model which use the finite-strain shell elements to model the airbag. the three-dimensional hydrostatic fluid elements to model the air-filled cavity, and the rebar elements to model the multi-ply nylon reinforcement of airbag. In addition, a three-dimensional rigid surface is used to define the contact between the airspring and metal bead. The air inside the airspring cavity has been modeled as a compressible fluid satisfying the ideal gas law. The conclusions of this study are as follows. 1) In the pressurization step of analysis, we could predict the change of vertical reaction force, cavity volume and pressure within the airspring. 2) In the second step of analyzing vertical static stiffness, the increase of the vertical load increases the vertical stiffness. 3) In case of changing the angle of nylon cord, the increase the angle of nylon cord increases the vertical stiffness.
운영기반의 철도시스템 RAMS 성능 요구사항 설계에 관한 연구
최성호(Sung-ho Choi),김길동(Gil-dong Kim),구정서(Jeong-seo Koo) 대한전기학회 2018 전기학회논문지 Vol.67 No.11
Recently the design of railway systems have been performed, based on the analysis of operational conditions and service targets, it is to optimize the effectiveness and efficiency of system operation. Many RAMS requirements have been developed to transform operation conditions into system design characteristics. However, our railway industry has not actived the application of RAMS into system design performance. According to short of RAMS application, many technologies that have been developed are not only applied the existing systems that is operating, but also have not succeed to apply for new systems. In order to design the effective and efficient railway systems that are optimized to operation conditions and service targets, a systems approach and RAMS management are necessary in railway development, operation and maintenance. Therefore, in this study, the RAMS performance requirement design methods are discussed. the allocation methods from system level to each devices of subsystems.
도시철도차량 추진제어장치 전력변환 소자 혼용 운용에 관한 연구
이상오(Sang Oh Lee),구정서(Jeong Seo Koo),한성호(Seong Ho Han),김태도(Tae Do Kim),김주태(Joo Tae Kim),고윤권(Yun Gwon Go),임동원(Dong Won Lim) 한국철도학회 2016 한국철도학회 학술발표대회논문집 Vol.2016 No.5
서울메트로에서는 4 호선 현대 VVVF 전동차 추진제어장치인 C/I 장치의 주 전력 변환소자를 GTO 에서 IGBT 로 변경하여 현차에 적용하는 연구가 진행 중으로 연구 초기 전동차에 혼용 설치하여 시험한 결과 IGBT Type 을 적용한 해당 차호(1 량)에서 GTO Type 이 적용되어 있는 타 차호(4 량)와 출력 전류 불균형으로 견인력 부족 현상이 발생하였다. 이러한 현상은 2 종류 전력소자의 동작 특성 차이로 기존 GTO Inverter 를 구동시키는 제어기 Switching 신호에 대해 IGBT Inverter 차량의 응답성능이 GTO 차량과 다르게 나타나는데 원인이 있는 것으로 파악되었다. 2 가지 전력소자를 1 편성 전동차에 혼용 사용하였을 때 차량간 발생 되는 응답성능을 맞추기 위해 IGBT 적용 차량에 제어기와 GDU 간 인터페이스 보드를 제작 설치하여 시험하였으며, 그 결과 GTO Type 과 IGBT Type 차량간 동등한 Switching 응답성능을 확보하며 혼용사용에 대한 호환성을 확인하였고 전동차 운행 시 정상적인 운행 성능과 편안한 승차감을 유지하도록 하였다. In Seoul Metro, Researching VVVF train of Line 4 by HYUNDAI what Changing and Applying State power conversion device IGBT of propulsion control device C/I from GTO. At initial we got a result when installed IGBT mixed GTO that was lack of traction from to imbalance of Output current between applied Type of IGBT(1-car) to applied Type of GTO(4-car). This phenomenon, two kinds of response performance of the IGBT Inverter vehicle to the controller Switching signal for driving the existing GTO Inverter differences in the operating characteristics of the power element is grasped that there is cause to appear unlike GTO car It was, To make balance with two power device when installed IGBT mixed GTO at one train, we installed interface board between the controller because matching the response performance to be generated between the vehicle when the mixed use one train. As a result, to ensure the GTO Type and IGBT Type vehicle between the uniform Switching response performance to verify its compatibility for mixed use, when the train service, was to maintain the normal operating performance and comfortable ride.