• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.266-269
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• 2004

A satellite ground control system (SGCS) which monitors and controls a geostationary satellite 24 hours a day has to achieve the system architecture assuring high-level availability and redundancy scheme. The SGCS for Communication, Ocean, and Meteorological Satellite (COMS) is currently being developed in Korea, which will be implemented to satisfy high availability (HA), expansibility, and compatibility in design. In order to implement the system architecture to meet these characteristics, the SGCS for COMS introduces the concept of the real-time distributed system structure based on redundancy scheme for high availability, data replication and sharing, and CORBA middleware.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.1049-1057
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• 2011

Today, most weapon systems operate as component systems of SoS(System of Systems) and they produce synergy effects in the battle field by interoperating. In addition, the acquisition issues on weapon systems have expanded into SoS context including sustainment analysis. Availability is the sustainment KPP(Key Performance Parameter) of weapon systems. In this paper, a simulation model is proposed to analyze the availability of SoS. The simulation model consists of 5 modules: Mission and Task, System, System RBD, Maintenance system and a simulation engine. Then it was implemented and applied to a SoS. As a result of the application, the simulation model could be applied for analyzing the availability of the SoS and provided information about critical tasks and risky component systems to complete the given mission of the SoS.

• 품질경영학회지
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• 제33권4호
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• pp.75-87
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• 2005

Generally speaking, weapon system is defined as a combination of primary system and support system which are evaluated by capability and operational availability respectively. Recently comparison of total life cycle cost shows that logistic support system is proved to be more important than primary system. However, until now systematic approach to support system development has not been applied in the area of developing support system. We need to construct a universal metric for effectiveness of logistic support system and to cut out whatever activities or support elements which do not contribute to the metric. This paper describes a new approach based on system engineering approach to logistic support system and also classifies five factors of failure, stock-out frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistic support system.

• 한국위성정보통신학회논문지
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• 제10권4호
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• pp.107-112
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• 2015

본 논문에서는 정지궤도 복합위성 2B에 대한 환경위성지상국 시스템의 성능지표의 하나인 가용도를 예측하기 위한 H/W 및 S/W 시스템 가용도의 수학적 모델링을 제시하고, 직렬연결 시스템에 대한 가용도 예측 방법을 제시하였다. 또한, 본 논문에서는 환경위성 지상국 시스템의 가용도 예측 결과를 산출하였으며, 그 가용도 예측 결과는 0.998072로 분석 되었다.

• 한국군사과학기술학회지
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• 제15권5호
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• pp.651-659
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• 2012

Target operational availability setting is the first step to setting up a goal which a weapon system development project have to achieve and doing RAM analysis during whole life of a weapon system. It is important as a key factor to doing RAM analysis in the early phase of weapon system development. This paper present a methodology to set a target operational availability for, especially, a warship when it develop. This methodology uses Operational Mode Summary/Mission Profile(OMS/MP) of the developing warship and RAM analysis results of similar warships to calculate wartime and peacetime target operational availability. It will be used in early phase of not only warship development but also army or aircraft weapon systems when these develop.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권4호
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• pp.272-279
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• 2016

Purpose: In order to fulfill the RAMS (Reliability Availability Maintainability and Safety) requirements in Korean railway systems, specific target metrics should be measured and met the requirements when ordering a new system. This paper presents a procedure to predict and demonstrate the availability, maintainability and safety of subway elevators, escalators and PSD (platform screen doors) systems. Methods: The system manufacturer predicts availability and maintainability with lab and field tested data. After installation, availability and maintainability are demonstrated based on the actual operational data. The data was collected from the FRACAS (Failure Report and Corrective Action System). Results: Methods and process of assessing and analyzing the availability, maintainability and safety are presented for elevating services and PSD systems. The data obtained through the actual operation of the equipment is analyzed and maintained to predict the RAMS based on the component and system level failure data acquired. Conclusion: This study presented an application using IEC 62278 and operational data which can be used in the design and development stage to achieve the RAMS target value of the subway elevators, escalators and PSD systems.

• 한국통신학회논문지
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• 제29권9B호
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• pp.818-825
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• 2004

고가용정 (high availability) 이란 하드웨어, 소프트웨어, 네트워크 등에 문제가 발생하였을 때 지속적으로 서비스를 제공해주는 가술을 말한다. 고가용성은 정보화 시대의 도래, 전자 상거래의 발전 및 정보 및 멀티미디어 서비스 등의 컴퓨팅 환경의 변화에 따라 점차 중요시되고 있다 특히 하루 24시간 일년 내내 서비스를 제공해 주어야 하는 네트워크 컴퓨팅 부분에서 고가용성은 필수 불가결한 것으로 인식되고 있다. 이에 본 논문에서는 멀티미디어 관광 정보시스템 (Multimedia Tourism Information System)을 위해서 고가용정 (high-availability) 리녹스 (Linux) 서버에 대해서 분석 연구 하여, 대안을 제시 하고자 한다.

• International Journal of Reliability and Applications
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• 제3권3호
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• pp.147-154
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• 2002

In this paper, we consider the warm standby redundant system(WSRS) which is consisted of an active unit, a standby unit and a switchover device. In addition, the switchover processing is controlled by a control module. The effect of failure of the control module is taken into account to develop our reliability model for the redundant structure. For the performance evaluation of a redundant system with the function of switchover processing which is assumed to cause the increase of the failure rate of the system, some reliability indices, such as availability, average availability, reliability and steady state availability, are considered.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 심포지엄 논문집 정보 및 제어부문
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• pp.84-86
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• 2005

The digital systems such as PLC or DCS have been applied to non-safety systems of nuclear power plants because of many difficulties in using analog systems. Nowadays, digital systems have been applied to safety systems of the plants such as reactor protection system. One of the main advantages of digital systems is applicability of automatic testing methods to the systems. The protection system requires high-reliability and high-availability because it shall minimize the propagation of abnormal or accident conditions of nuclear power plants. The calculation of reliability and availability of systems depends on the maintenance period of the system. In general, the maintenance period of the protection system is one-month in case of the manual test. However, the cycle of test can be shortened in several hours by using automatic periodic testing. The reliability and availability of the system is better when test period is shortened because the reliability and availability is inverse proportion to the test period. In this research, we developed the automatic periodic testing method for KNICS Reactor Protection System, which can test the system automatically without an operator or a tester. The automatic testing contained all functions of reaction protection systems from analog-to-digital conversion function of the bistable Processor to the coincident trip function of the coincident processor. By applying the automatic periodic testing to reaction system, the maintenance cost can be cut down and the reliability can be increased.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.547-550
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• 2008

최근에 블로그, UCC, IPTV 등 사용자 중심의 인터넷 서비스와 언제 어디서나 웹을 통해 서비스를 받을 수 있는 유비쿼터스 컴퓨팅 환경으로의 변화는 안정된 서비스를 제공할 수 있는 고가용 시스템 플랫폼을 필요로 한다. 고가용 시스템이란 네트워크상에 서버들을 클러스터로 구성함으로써 만약 서비스 하던 시스템이 고장과 같은 시스템 장애가 발생하더라도 계속해서 안전하게 서비스를 제공할 수 있는 시스템을 말한다. 그리고 이러한 고가용 시스템 플랫폼에서 서비스의 신뢰성을 위해 시스템 간 데이터 동기화는 필수적이다. 본 논문에서는 리눅스 고가용 시스템에서 로컬 디스크 간 실시간 데이터 동기화 기술인 DRBD(Distributed Replicated Block Disk)를 구현하였다.