• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.2
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• pp.37-52
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• 1980

Recent industrial processes have been complicated and automated. In order to improve the system reliability and solve the limitation of human ability, the necessity of alarm analysis or fault diagnosis has been rapidly grown, A "dictionary" made by a sequence computer programming has been developed as one of the mothods for fault diagnosis in the chemical industrial processes and its usefulness has been proved through the experiment. It also suggests a way to simplity the recent alarm system being complex.g complex.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.297-301
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• 2004

세탁기의 Shaft Ass'y는 모터로부터 동력을 전달 받아 세탁 및 탈수행정의 제어 기능을 수행하는 세탁기의 핵심부품으로 사용 중 브레이크 밴드소음을 유발하여 소비자의 불만족 요소로 작용하고 있다. 그러나 드럼과 브레이크 페드의 정확한 마찰소음 현상 규명이 안되어 불량 개선에 많은 어려움이 있다. 이를 해결하고자 소음, 진동, 소재 분석 및 ESPI(Electronic Speckle Pattern Interferometry) 분석을 통해 고장원인을 규명하였다. 특히 ESPI는 비접촉, Full Field 정밀 변형 가시화 장치로 Shaft Ass'y의 동작 중 공진소음 발생 부위를 변형 가시화를 통해 정확하게 찾을 수 있었다. 밴드소음 원인은 브레이크 Lever의 공진에 의해 발생하였고 브레이크 밴드 패드의 접촉면적 불균일로 인한 국부적 마찰력 증대가 소음원으로 작용하였다. 밴드소음의 정확한 고장 메커니즘 규명을 통해 개선안을 도출하여 적용하였고 밴드소음 개선효과를 얻을 수 있었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.297-302
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• 1998

최근 원자력산업계 동향은 기기의 노후화, 예비품 확보의 어려움, 그리고 기존 설비에 대한 보수비용 증가 등의 이유로 아날로그 계측제어 설비들을 컴퓨터-기반 설비로의 부분적인 개선이나 전체적인 교체가 추진되고 있다 그러나 컴퓨터-기반 설비는 소프트웨어와 하드웨어가 환경영향에 민감하고, 공통모드고장을 일으킬 수 있는 프로그래밍 설계오류의 잠재성이 있는 것으로 알려져 있다. 공통모드고장을 방지할 수 있는 가장 설득력 있는 해결방안은 철저한 품질보증, 심층방어 및 다양성 설계기법으로 평가되고 있다. 본 논문에서는 컴퓨터-기반 계측제어계통의 심층방어 및 다양성에 관한 규제기준과 정성적 평가를 위한 블록개념을 소개하고, 평가의 사례로서 CE System 80+와 국내 가동중인 W형 원전의 설비개선에서 주급수 상실시 컴퓨터-기반 설비의 공통 모드고장에 따른 다양성과 심층방어계층을 평가하였다. 특히 국내 가동중인 W형 원전에 대해서는 그 평가결과를 근거로 하여 ATWS 완화설비의 설치를 제안하였다.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.235-237
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• 2005

철도차량에 취부되는 추진장치는 차량의 성능을 결정하는 매우 중요한 요소이다. 이러한 추진장치에 대한 다양한 성능을 평가하고 진단하기 위해 상시계측시스템을 구축하여 활용하고 있다. 이러한 계측장비들은 추진장치에 대한 계측 및 분석을 통한 시험을 평가하고 완성차 시험이나 본선시운전 시험시에 발생할 수 있는 고장원인을 찾아내고 해결하는데 많은 도움을 주고 있다 본 논문에서는 한국형 고속전철차량에 설치되어있는 상시계측시스템을 통해 추진장치에 대한 고장진단을 실시한 내용에 대하여 기술하였다.

• Proceedings of the KIEE Conference
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• summer
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• pp.1313-1315
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• 2004

고속철도는 수많은 하이테크 기술의 결정체이며, 이 중에서도 주변압기, 주전력변환장치 및 주전동기는 차량의 성능을 결정하는 매우 중요한 요소이다. 이러한 전장품들에 대한 다양한 성능을 평가하고 진단하기 위해 상시계측시스템을 구축하여 활용하고 있다. 이러한 계측장비들은 여러 전장품에 대한 계측 및 분석을 통한 시험평가와 동시에 완성차시험이나 본선시운전 시험시에 발생할 수 있는 고장원인을 찾아내고 해결하는데 많은 도움을 주고 있다. 본 논문에서는 상시계측시스템을 통해 주변압기, 주전력변환장치, 전동기 등에 대한 고장진단을 실시한 내용에 대하여 연구하였다.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.3
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• pp.319-328
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• 2000

The Message-Passing Interface(MPI) is a standard interface for parallel programming environment, based on that application programs run on the processors of a parallel computer. Processor nodes execute processes consisting the program by passing messages to one another. During executing, however, if a fault occurs on a processor node or a process, this will result an inconsistent state, and consequently, the whole program will have to be stopped. To solve this problem, in this paper, we propose a fault-tolerant message passing interface(FT-MPI) by adding a fault manager module to MPI. The proposed FT-MPI does not need any hardware support, and each application program based on MPI can run on the FT-MPI without any modification. The proposed fault tolerance scheme uses the so-called hot-spare process duplication method, and verified by simulations that application programs run despite of any fault with less than 5% overhead on execution time.

• Journal of KIISE:Databases
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• v.32 no.6
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• pp.616-627
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• 2005

In the shared storage file system, systems can directly access the shared storage device through specialized data-only subnetwork unlike in the network attached file server system. In this shared-storage architecture, data consistency is maintained by some designated set of lock servers which use control network to send and receive the lock information. Furthermore, lease mechanism is introduced to cope with the control network failure. But when the control network is partitioned, participating systems can no longer make progress after the lease term expires until the network recovers. This paper addresses this limitation and proposes a method that allows partitioned systems to make progress under the partition of control network. The proposed method works in a manner that each participating system is rotationally given a predefined lease term periodically. It is also shown that the proposed mechanism always preserves data consistency.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.70-77
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• 2004

In many industrial applications, an unexpected fault of induction motor drive systems can cause serious troubles such as downtime of the overall system heavy loss, and etc. As one of methods to solve such problems, this paper investigates the fault diagnosis for open-switch damages in a voltage-fed PWM inverter for induction motor drive. For the feature extraction of a fault we transform the current signals to the d-q axis and calculate mean current vectors. And then, for diagnosis of different fault patterns, we propose a clustering based diagnosis algorithm The proposed diagnostic technique is a modified ANFIS(Adaptive Neuro-Fuzzy Inference System) which uses a clustering method on the premise of general ANFIS's. Therefore, it has a small calculation and good performance. Finally, we implement the method for the diagnosis module of the inverter with MATLAB and show its usefulness.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.1
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• pp.9-18
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• 2015

Software Reliability Growth Models (SRGMs) are useful for determining the software release date or additional testing efforts by using software failure data. It is not appropriate for a SRGM to apply to all software. And besides a large number of SRGMs have already been proposed to estimate software reliability measures. Therefore selection of an optimal SRGM for use in a particular case has been an important issue. The existing methods for selecting a SRGM use the entire collected failure data. However, initial failure data may not affect the future failure occurrence and, in some cases, it results in the distorted result when evaluating the future failure. In this paper, we suggest a method for selecting a SRGM based on the evaluation goodness-of-fit using partial data. Our approach uses partial data except for inordinately unstable failure data in the entire failure data. We will find a portion of data used to select a SRGM through the comparison between the entire failure data and the partial failure data excluded the initial failure data with respect to the predictive ability of future failures. To justify our approach this paper shows that the predictive ability of future failures using partial data is more accurate than using the entire failure data with the real collected failure data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.410-417
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• 2018

System design errors are more likely to occur in modern systems because of their steadily increasing size and complexity. Failures due to system design errors can cause safety-related accidents in the system, resulting in extensive damage to people and property. Therefore, international standards organizations, such as the U.S. Department of Defense and the International Electrotechnical Commission, have established international safety standards to ensure system safety, and recommend that system design and safety activities should be integrated. Recently, the safety of a system has been verified by modeling through a model-based system design. On the other hand, system design and safety activities have not been integrated because the model for system design and the failure model for safety analysis and verification were developed using different modeling language platforms. Furthermore, studies using UML or SysML-based failure models for deriving safety requirements have shown that these models have limited applicability to safety analysis and verification. To solve this problem, it is essential to extend the existing methods for failure model implementation. First, an improved SysML-based failure model capable of integrating system design and safety verification activities should be produced. Next, this model should help verify whether the safety requirements derived via the failure model are reflected properly in the system design. Therefore, this paper presents the concept and method of developing a SysML-based failure model for an automotive system. In addition, the failure model was simulated to verify the safety of the automotive system. The results show that the improved SysML-based failure model can support the integration of system design and safety verification activities.