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철도 신호시스템의 Fail-Safe 네트워크를 위한 DPST(Dual Packet Seamless Transfer) 프로토콜의 구현
김경식(Kim Kyung-Shik),류신형(Ryu Shin-Hyung),권철(Kwon Cheol),이종성(Lee Jong-Seong) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.5월
열차제어 지상신호시스템에서 핵심적인 철도보안기능을 수행하는 연동장치는 철도산업의 안전성 확보지침에 따라 높은 안전성과 신뢰성을 갖추어야만 한다. 따라서 연동장치는 높은 안전성과 신뢰성을 달성할 수 있도록 실시간 운영체제 및 그 구성 하드웨어의 랜덤 고장에 대처하기 위한 Fail-Safe형 다중 제어시스템으로 구성된다. 이러한 구성에서는 운영자 인터페이스를 포함한 다양한 장치와의 메시지 교환을 위한 인터페이스 기능을 구현하기 어려운 특성이 존재한다. 본 논문에서는 연동장치와 상위 인터페이스 설비간의 통신기능을 구현하기 위한 Dual Ethernet 네트워크 구성 및 DPST(Dual Packet Seamless Transfer) 통신 프로토콜을 제안한다. 제안된 시스템의 구성에서는 특정 네트워크 장비의 랜덤 고장이나 통신오류에 강인한 특성을 보이며 통신채널의 장애를 검출할 수 있는 기능이 추가되어 설비의 유지보수에 효과적인 정보로 활용될 수 있음을 실험적으로 검증한다. 제안된 네트워크 구성 및 운영 프로토콜을 현대제철 전용철도용 전자연동장치에 구현하고 그 성능과 특성을 유럽표준규격 EN50159의 지침을 토대로 타당성을 분석한다. An interlocking equipment of railway signalling systems should have very high functional safety and reliability properties because of its vital railway protection functionality. In order to achieve the required safety and reliability level, an engineer, in general, designs and implements the interlocking equipment to operate under RTOS(Realtime Operating System) environment, and the control hardware architecture redundant to cope with the random failures of system or subsystem. In such an architecture, it's very difficult to implement the interlocking equipment to communicate with various interface systems including the signal operator's terminal. In this paper, we propose a dual ethernet network topology and dual packet seamless transfer protocol algorithm for railway signaling system such as the interlocking equipment. We verify in this paper that the proposed DPST protocol algorithm has the evidence of its robust properties against the random hardware faults and communication errors. The proposed communication structure and algorithm is implemented in the electronic interlocking equipment for the private railway system of Hyundai Steel Company and its performance and properties are validated on the guideline of European Railway Standard EN50159.
다중벽 탄소나노튜브를 함유한 PC/ABS 복합재의 마모 특성 및 다중벽 탄소나노튜브의 유출 평가
이현우(Hyun-Woo Lee),김경식(Kyung-Shik Kim),이재혁(Jae-Hyeok Lee),김효섭(Hyo-Sop Kim),김재호(Jae-Ho Kim),오동훈(Dong-Hoon Oh),류상효(Sang-Hyo Ryu),장영찬(Young-Chan Jang),김재현(Jae-Hyun Kim),이학주(Hak-Joo Lee),김광섭(Kwang-Seop Kim 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.5
Carbon nanotubes (CNTs) are used in various composite materials to enhance electrical, thermal and mechanical properties of composite materials. In this study, we investigate the wear characteristics of polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) blends containing multi-walled carbon nanotubes (MWCNTs). PC/ABS blends are commonly used in many industrial applications such as cellular phones and display cases and MWCNTs have been added to the PC/ABS blends to improve their electromagnetic interference shielding (EMS). We performed wear tests on PC/ABS blends containing MWCNTs under reciprocating linear sliding conditions with chrome steel balls as a counterpart material. The normal loads were 10, 30, 50, 70, 100 N, the sliding speed was 10 mm/s, the stroke length was 15 mm, and the tests lasted 900 s. The MWCNTs included in the PC/ABS blends lower the wear volume and friction coefficient of the composites. We analyzed the wear debris collected from the composites during the tests in terms of the MWCNT concentration using inductively coupled plasma optical emission spectroscopy. The results show that the quantity of MWCNTs in the debris is proportional to the concentration of MWCNTs in the composite, indicating that the exposure of the MWCNTs to environments by wear could be increased with their concentration in the composite.
김창현(Chang-Hyun Kim),이상봉(Sang-Bong Lee),조경민(Kyungmin Jo),김상민(Sangmin Kim),원세정(Sejeong Won),김경식(Kyung-Shik Kim),김광섭(Kwang-Seop Kim),김재현(Jae-Hyun Kim),이학주(Hak-Joo Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In this work, we investigated the effects of the number of graphene layer on the stretchability of graphene electrode. CVD?grown graphene was transferred onto a flexible transparent substrate through dry transfer process. Tensile tests for each specimen were carried out to investigate the electro-mechanical properties of graphene electrode with the number of graphene layer. During the tensile test, we measured the electrical resistance of graphene electrode and the load applied on the electrode simultaneously. The results show that stacking graphene sheets onto flexible substratesis effective to reduce the resistance change of graphene electrode
김홍록(Hong Rok Kim),김경식(Kyung Shik Kim) 한국여가레크리에이션학회 1997 한국여가레크리에이션학회지 Vol.14 No.-
The primary purpose of dais study was to probe the causal relationship between participation in sport for all program and leisure satisfaction, life satisfaction of older persons. The subjects of this study were divided by two groups : 200 involvers in leisure sport program and 200 non-involvers. The data collected questionnaire designed for this study were consisted of responses to items constructed to represent each variable. For data analysis, multiple regression and path analysis were used. The major findings obtained from this study were following. There existed significant casual relationship among daily participation in sport for all program of alder persons, leisure satisfaction, and life satisfaction. It was also found that participation in sport for all program of older persons facilitated the leisure satisfaction, it finally leaded to life satisfaction. Based upon these findings and within limitations of this study, it was concluded that participation in sport for all program of older persons would increase the leisure satisfaction and these increasement finally would influence individual`s overall life satisfaction.