• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 가을 학술발표논문집 Vol.29 No.2 (2)
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• pp.19-21
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• 2002

Writing requirements in formal notation for a safety-critical system can improve software quality and reduce the errors that may arise later on in the software development life cycle. In this paper, we propose a formal specification approach used to describe the nuclear control system. The approach is based on the existing AECL approach that was the only formal specification technique applied to nuclear control systems in the past. Although the approach is AECL-based, the complex descriptions of certain requirements have been reduced by using different specification techniques. We discuss the differences and how the proposed approach provides not only specification but also verification environment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.483-494
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• 2009

Since the embedded system is more intelligent, the importance of the reliability in the embedded system is a lot more visible. Especially the reliability of the embedded system in the train control system is even better important. As the special quality of the embedded system, the hardware of the system is directly controlled by the software in the embedded system. As the expansion of complexity, the expense amd the time for verification is required more and more. This paper is presented the verification of the reliability as the method with background of failure Embedded system is gradually, the importance of 'A built-in on the system embedded system's reliability is focused. In particular, in the train control system built-in of the embedded system, reliability is even more important. The embedded system of the system controls over hardware, software with built-in directly. The more complex system is, the more increasable of depending on the reliability of the time verification and expensive is. This paper is about he characteristics of the reliability and verification of embedded system under the failure mechanisms, based on the verification methodology suggested by in the train control system.

• Journal of Power Electronics
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• 제11권4호
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• pp.576-582
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• 2011

This paper presents a novel control strategy for selective compensation of power quality (PQ) problems, depending upon the limited rating of voltage source inverters (VSIs), through a unified power quality conditioner (UPQC) in a three-phase four-wire distribution system. The UPQC is realized by the integration of series and shunt active power filters (APFs) sharing a common dc bus capacitor. The shunt APF is realized using a three-phase, four-leg voltage source inverter (VSI), while a three-leg VSI is employed for the series APF of the three-phase four-wire UPQC. The proposed control scheme for the shunt APF, decomposes the load current into harmonic components generated by consumer and distorted utility. In addition to this, the positive and negative sequence fundamental frequency active components, the reactive components and harmonic components of load currents are decomposed in synchronous reference frame (SRF). The control scheme of the shunt APF performs with priority based schemes, which respects the limited rating of the VSI. For voltage harmonic mitigation, a control scheme based on SRF theory is employed for the series APF of the UPQC. The performance of the proposed control scheme of the UPQC is validated through simulations using MATLAB software with its Simulink and Power System Block set toolboxes.

• 한국철도학회논문집
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• 제13권4호
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• pp.412-418
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• 2010

본 논문에서는 최근 들어 철도신호시스템분야에서 중요한 이슈로 부각되고 있는 소프트웨어 측면에서의 신뢰성과 안전성 수준을 국제규격(IEC 62279)에 부합할 수 있도록 하기 위한 접근방법을 모색하며, 실제 적용사례(국토해양부 및 한국건설교통기술평가원이 주관하는 국가 대형연구개발 실용화 사업인 "도시형 자기부상열차 실용화사업 시범노선 건설 열차제어시스템 구매/설치")를 통하여 현실적이고 접근가능한 구체적인 활동 사항들을 프로젝트 수행과 연관하여 기술한다. 또한 열차제어시스템의 안전성 인증 획득을 위한 소프트웨어를 포함한 시스템 보증활동 및 시스템 보증을 위한 조직체계를 확립하고, 요구사항 관리 및 프로젝트 공정에 따른 절차적 시스템 보증 활동과 안전성평가 활동과의 연관관계, 시스템 전반에 걸친 RAMS 및 소프트웨어 품질보증 활동과 안전성 평가를 통한 인증활동에 대한 부분을 상세 제시하고자 한다. 본 활동을 통하여 지금까지 국제규격에 따른 활동기준에 대해서 모호하거나, 명확하게 정의되지 않은 사항들이 체계적으로 정리될 수 있을 것으로 사료되며, 타 사업 및 국내 철도신호시스템 적용을 위한 소프트웨어 품질 및 안전 무결성 수준 확보에 따른 안전성 확보방안의 구체적인 케이스 모델이 될 것으로 기대된다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권2호
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• pp.877-881
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• 2014

Objective: To evaluate risk factors for gallstones after gastrectomy. Methods: To identify documents published from 1990 to 2011 the Pubmed, Cochrane Library, Springer Link, CBM and WanFang databases were searched and a meta-analysis was performed with RevMan 5.2 software for odds ratios and 95%CIs. Results: Fifteen studies were selected for the meta-analysis. The pooled ORs [95%CIs] were 0.56 [0.43, 0.73], (P<0.0001) for digestive tract reconstruction, 0.80 [0.54, 1.17], (P=0.25) for pylorus preservation, 0.33[0.15, 0.75], (P=0.008) for resection scope of stomach, 0.33 [0.15, 0.75], (P=0.008) for lymphadenectomy, and 0.13 [0.05, 0.33], (P<0.0001) for vagotomy. Conclusions: Digestive tract physical reconstruction and vagus nerve preservation can reduce the morbidity of gallstones after gastrectomy. Total gastrectomy can add to the morbidity of galltones as does increasing the degree of lymph node dissection. There was no significant difference in gallstones with or without pylorus preservation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.164-168
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• 2005

In this paper a statcom is developed to improve the power quality in a dc traction system. The proposed statcom can be used as both inverter and active filter. As an active filter, it can compensate harmonic distortion and reactive power and as an inverter, it can recycle regenerative energy caused by decelerating trains. The simulation results are carried out by using PSCAD/EMTDC software.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.205-223
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• 2018

During launch a spacecraft is subjected to a variety of dynamical loads transmitted through the launcher to spacecraft interface or air-born transmission excitations in the acoustic pressure field inside the fairing. As a result, spacecraft are tested on ground to ensure and demonstrate the global integrity of the structure against these loads, to screen the flight hardware for quality of workmanship and to validate mathematical models. This paper addresses the numerical modelling and simulation of the low frequency sine and random vibration tests performed on electrodynamic shaker facilities to comprise the mechanical-borne transmission loads through the launcher to spacecraft interface. Consequently, the paper reviews techniques and methodologies to derive a reliable and representative coupled virtual vibration testing simulation environment based on experimental data. These technologies are explored with the main objectives to ensure a stable, reliable and accurate control while testing. As a result, the use of the derived simulation models in combination with the added value of improved control and signal processing algorithms can lead to a safer and smoother vibration test control of the entire environmental test campaign.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1669-1679
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• 2010

Related to the on-going "Train Control System Project of Pilot Line Construction for Urban MAGLEV Train", activities by each phase shall be conducted to achieve SIL4 level and obtain safety certification from the Independent Safety Assessment(ISA), based on the IEC standards((IEC 62278/62279 and IEC 62425) for the first time in Korea. This thesis describes the introduction of IEC standards, system assurance activities (such as plan, analysis, test, verification and validation) in compliance with requirements management and project life-cycle and relations with the safety assessment activities; and certification activities (such as document reviews and audits) through system RAMS activities, software quality assurance activities and safety assessment, for the purpose of achieving a successful safety certification at the time of completing the project as system assurance activities including software and safety certification activities in order to acquire the safety certification for train control system which does not exist at all in domestic cases. It is believed that overall system safety assurance activities in this project will contribute to develop more upgraded products of the domestic train control system on the quality and safety point of view, find overseas markets and establish a bridgehead in the future.

• 방송공학회논문지
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• 제17권4호
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• pp.670-675
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• 2012

정지영상 및 동영상내의 화면에서 관심영역이 설정되고, 비관심영역에 비하여 관심영역에 높은 화질이 제공되면 전체적으로 주관적 화질이 증대하게 된다. 관심영역은 색상 카메라만을 이용하여 추출하게 되면 계산이 복잡해질 뿐만아니라 추출의 정확도도 떨어지게 된다. 따라서 본 논문에서는 관심영역을 설정하기 위하여 깊이 카메라를 이용하며, 카메라와 관심영역 객체별 거리를 산출하고, 거리에 따라 객체의 화질을 차별적으로 제어하는 방법을 제안한다. 즉, 거리가 먼 객체에는 높은 양자화 계단크기를 적용하지만, 상대적으로 거리가 가까운 객체에는 낮은 양자화 계단크기를 적용하여 화질을 좋게 한다. 본 논문에서 제안된 방법에 의해 객체의 거리별로 양자화계단의 크기를 차등적으로 적용함으로써 주관적 화질의 개선이 이루어졌으며 모의실험을 바탕으로 확인할 수 있다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 추계학술대회
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• pp.527-537
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• 2009

다양한 리스크 문제가 발생하고 있는 환경 속에서 리스크에 대한 적절한 대응을 하고 안정화를 도모함과 동시에 리스크 문제가 표면화되어 초래하는 영향을 극소화 하기 위한 새로운 패러다임의 경영시스템 도입이 주요 전략과제로 대두되고 있다. 본 연구에서는 리스크 경영시스템(Risk Management System)인 IEC 61508의 리스크 규격을 중심으로 소프트웨어 분야가 가지고 있는 리스크 문제를 효과적으로 관리 할 수 있는 대안 모색을 가능하도록 하고 소프트웨어 분야에서의 리스크 제로와 안전 강화를 위하여 기초 자료를 제시하였다.