• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2090-2100
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• 2011

Railway rail fastening system is the critical device which gives big influences to not only the vehicle driving stability and the orbit's structural stability against the impulsive load, but also the noise vibration and the ride comfort. As a part of the low-carbon green growth, the importance of the railroad industry is getting highlights on its excellent energy-efficiency and eco-friendliness. However, so far the Korea's domestic rail fastening system technology is not so good and the technical reliance to abroad is very heavy. In this study, we conducted comparative analysis on the rail fastening system with new and used one of the same type. And those systems are imported by Seoul Metro and are being used by it. With this basis, we developed the components and the materials and then, established the durability assessment methods appropriate to the Korean domestic circumstances. And through the reliability qualification test on the 7 parts of the rail fastening system, we've improved the reliability and guaranteed the 15 years of service lifetime. ($B_{10}Life15$) Establishment and standardization of Reliability Standard on the parts of the rail fastening system such as anti-vibration pads, guide-plate, screw spike made it possible to perform the internationally fair assessment. And it is thought that we can satisfy the manufactures' and consumers' needs of cost-cutting and qualification security by shortening of assessment period on rail fastening system.

• 대한산업공학회지
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• 제43권2호
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• pp.147-153
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• 2017

In order to demonstrate a target reliability with a specified confidence level, a new two-stage Bayesian Reliability Demonstration Test (RDT) plans that is known to be more effective than a corresponding single-stage one is proposed and developed by Bayesian framework with beta prior distribution for Weibull life time distribution. A numerical example is provided to illustrate the proposed RDT plans and compared with other non-Bayesian and Bayesian plans. Comparative results show that the proposed Bayesian two-stage plans have some merits in terms of required and expected testing time and probability of acceptance.

• 한국항행학회논문지
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• 제13권5호
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• pp.763-772
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• 2009

정보화 사회가 추진됨에 따라 다양한 행정정보보호시스템의 개발이 이루어지고, 국가 및 공공기관에서도 안전한 서비스 제공을 위해 행정정보보호시스템의 도입이 증가하고 있다. 특히 행정정보보호시스템은 보안성에 대한 검증이 무엇보다 중요시 되므로 행정정보보호시스템의 보안성 평가 서비스에 대한 관심이 증가하고 있다. 이에 따라 국 내외적으로 다양한 보안성 평가 서비스에 대한 연구가 진행되고 있다. 이에 본 논문에서는 영국 및 캐나다의 보안성 평가 서비스를 분석하고, 이를 바탕으로 국내의 국가 및 공공기관의 사용자에게 신뢰성을 제공할 수 있는 행정정보보호시스템의 사전 검증 도입방안에 대해서 제안한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2603-2605
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• 2005

This paper describes an experience on the equipment qualification of CRCS(control rod control system) that has been developed for nuclear power plants. A very high level criteria should be satisfied for the equipment to be used for nuclear power plants. We have developed a CRCS that is aimed to be applied to commercial plants. This system adopts a duplex system structure that is based on the state-of-the-art digital technology so that it has higher reliability than the existing systems. The CRCS has been tested at a licensed testing organization and finally qualified. In this paper, the procedures and some trial-and-errors we have been through in the qualification process are explained. It is expected that our experience will be a helpful tips to the industry that are developing various systems for safety-critical plants.

• 한국분말재료학회지
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• 제24권6호
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• pp.494-507
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• 2017

A three-dimensional physical part can be fabricated from a three-dimensional digital model in a layer-wise manner via additive manufacturing (AM) technology, which is different from the conventional subtractive manufacturing technology. Numerous studies have been conducted to take advantage of the AM opportunities to penetrate bespoke custom product markets, functional engineering part markets, volatile low-volume markets, and spare part markets. Nevertheless, materials issues, machines issues, product issues, and qualification/certification issues still prevent the AM technology from being extensively adopted in industries. The present study briefly reviews the standard classification, technological structures, industrial applications, technological advances, and qualification/certification activities of the AM technology. The economics, productivity, quality, and reliability of the AM technology should be further improved to pass through the technology adoption lifecycle of innovation technology. The AM technology is continuously evolving through the introduction of PM materials, hybridization of AM and conventional manufacturing technologies, adoption of process diagnostics and control systems, and enhanced standardization of the whole lifecycle qualification and certification methodology.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.3975-3984
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• 2022

Distributed control system architecture is adopted for I&C systems of Prototype Fast Breeder Reactor, where the geographically distributed control systems are connected to centralized servers & display stations via switched Ethernet networks. TCP/IP communication plays a significant role in the successful operations of this architecture. The communication tasks at control nodes are taken care by TCP/IP offload modules; local area switched network is realized using layer-2/3 switches, which are finally connected to network interfaces of centralized servers & display stations. Safety, security, reliability, and fault tolerance of control systems used for safety-related applications of nuclear power plants is ensured by indigenous design and qualification as per guidelines laid down by regulatory authorities. In the case of commercially available components, appropriate suitability analysis is required for getting the operation clearances from regulatory authorities. This paper details the proposed approach for the suitability analysis of TCP/IP communication nodes, including control systems at the field, network switches, and servers/display stations. Development of test platform using commercially available tools and diagnostics software engineered for control nodes/display stations are described. Each TCP link behavior with impaired packets and multiple traffic loads is described, followed by benchmarking of the network switch's routing characteristics and security features.

• Advances in aircraft and spacecraft science
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• 제5권2호
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• pp.239-249
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• 2018

Physical tests are performed at various stages of the development cycle of a product, from prototype validation to product qualification. Although costly, there are growing demands for qualification tests like endurance vibration testing to be more representative of the real world. At the same time there are growing demands to assess the durability of these items based on FEA simulation. In this paper, we will explain how to set up a CAE-based test and how to correlate the results with some physical measurements. Specific assumptions will be explained and some advantages of using virtual tests will be highlighted such as the reduction of the number of prototypes needed, investigations on failures, evaluation of the level of reliability via sensitivity analysis, evaluation of the margins are at the end of a successful test. This presentation will therefore focus on explaining and showing how virtual tests can enrich the exploitation of physical tests.

• 융합보안논문지
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• 제16권1호
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• pp.13-21
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• 2016

민간경비가 도입된 지 60여년이 지난 현재 민간경비와 관련된 국가공인 자격으로는 경비지도사와 신변보호사 자격제도가 있다. 본 연구에서는 2013년도부터 국가공인자격으로 실시 되어오고 있는 신변보호사 자격검정 사항 중에서 2차 실기시험제도의 문제점에 대하여 논의하였다. 현행 신변보호사 자격검정은 1차 학과시험과 2차 실기시험으로 분류하여 실시하고 있는 가운데 신변보호사의 자격 검증을 엄격히 하여 응시자에 대한 만족도와 대중의 신뢰도를 높여가야할 시기에 봉착하였다고 판단되어 신변보호사 실기시험제도의 문제점에 대한 개선방안을 다음과 같이 제시하였다. 첫째, 현재 단순하고 비교적 기초적인 실기시험 평가 항목의 난이도를 다양화 하여 구분하는 것이 필요하다. 둘째, 현재 실기시험 평가기술은 합기도의 기술분야에 치우쳐 있다고 볼 수 있어 각 무도분야의 실질적 활용가능성이 높은 기술을 복합적으로 접목시켜 다양화 하는 것이 필요하다. 셋째, 현재 일반화 되지 않은 실기시험 평가위원제도를 전문화된 실기시험 평가위원으로 선정할 수 있도록 기준안 마련이 필요하다. 넷째, 현재 실기시험 평가위원과 응시자의 관계에 있어 지인인 경우가 많아 객관성확보차원에서 제척제도를 신설하는 것이 필요하다. 이와 같이 신변보호사 자격검정 실기시험제도의 전문성을 고양시켜나가기 위해 관련기관의 제도적 개선이 시급히 이루어져야 할 것이다.

• 항공우주시스템공학회지
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• 제12권1호
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• pp.47-56
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• 2018

본 논문에서는 정지궤도복합위성 추진계 배관망의 독자적인 구조해석을 실시하였고, AIRBUS의 구조해석결과와 비교분석을 통해 추진계 배관망의 구조적 건전성 및 해석방법의 신뢰성을 평가하였다. 추진계 배관망의 구조적 신뢰성 확보는 정지궤도복합위성 추진계의 매우 중요한 핵심요소이다. 따라서 CAE 프로그램을 통해 직접 추진계 배관망 모델링을 수행하였고, 발사환경에서 구조해석을 실시하여 응력을 도출하였다. 내압응력해석, 조립정렬해석, 정현파진동해석, 랜덤진동해석의 하중조건에 따라 Hoop stress, Axial stress, Bending stress, Torsion stress를 구하였고, 이를 모두 고려한 von Mises 응력 계산 후 안전여유 결과 값을 도출함으로써 추진계 배관망의 구조적 건전성을 판단하였다.

• 비파괴검사학회지
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• 제24권2호
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• pp.158-162
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• 2004

발전설비에서 용접 구조물의 신뢰성은 매우 중요하며, 구조물 신뢰성평가를 위해서는 재료물성의 정확한 평가에 근거되어야 한다. 발전설비의 건설중 용접부의 물성평가는 실제 용접부에서의 파괴시험이 어려우므로 현장 용접부와 유사하게 용접, 시험한 결과인 PQR(Procedure Qualification Record)에 의해서만 보증을 하고 있다. 이런 문제점을 해결하기 위하여 현장 용접부에 대하여 비파괴적으로 기계물성 측정이 가능한 연속압입시험법을 적용하였다. 연속압입시험법은 압입시 압입하중-깊이를 측정하여 항복강도, 인장강도 그리고 가공경화지수와 같은 기계적 특성들의 분석이 가능한 시험법으로, 화력 발전소 건설 및 운전중 주증기관과 재열증기관의 기계인장물성을 평가하기 위하여 적용하였다.