• Journal of the Korean Data and Information Science Society
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• 제18권2호
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• pp.535-541
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• 2007

The Non-homogeneous Poisson process is probably the most popular model since it can model systems that are deteriorating or improving. The renewal process is a model that is often used to describe the random occurrence of events in time. But both these models are based on too restrictive assumptions on the effect of the repair action. The Modulated Power Law Process is a suitable model for describing the failure pattern of repairable systems when both renewal-type behavior and time trend are present. In this paper we propose maximum likelihood estimation of the next failure time after the system has experienced some failures, that is, Mean Time Between Failure for the MPLP model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.70-72
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• 1999

Actuator (chopper) and sensors failures resulting from electric shock and mechanical vibration generating by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension systems. Thus, this paper proposes the reliable output feedback controller for the electromagnetic levitation systems against actuator, air-gap sensor and acceleration sensor failures. The designed controller is an extend version of a novel design technique which has the design method of the output feedback controller using dynamic compensator. The benefits of this scheme are demonstrated through the experimental results for the proposed controller against chopper, air-gap sensor and acceleration sensor failures of electromagnetic levitation system.

• 연구논문집
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• 통권30호
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• pp.79-92
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• 2000

Chopper and sensors failures resulting from electric shock and mechanical vibration generated by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension systems. Thus, this paper proposes a reliable output feedback control scheme for the electromagnetic suspension systems in the present of chopper, gap sensor and acceleration sensor failures. The designed controller is an extended version of a novel design technique which has the design method of the output feedback controller using dynamic compensator. The benefits of this scheme are demonstrated through the simulation and experimental results for proposed controller against chopper, gap sensor and acceleration sensor failures of electromagnetic suspension system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1411-1413
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• 2000

Distubance of air-gap sensors by rail irregularities are the serious problem deteriorating the performance in the electromagnetic suspension (EMS) systems. Thus, this paper proposes the output feedback controller with discrete kalman filter for the EMS systems. The discrete kalman filter estimate true state value and output feedback controller guarantee stability. The benefit of this scheme are shown by simulation. Therefore air-gap disturbance are rejected successfully.

• 한국전자통신학회논문지
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• 제15권4호
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• pp.617-624
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• 2020

급속한 속도로 과학기술이 나날이 발전하고 있는 현 추세와 더불어 방위산업의 주요특성인 개발기간의 장기화, 설계의 복잡성, 긴 수명주기로 인한 높은 부품단종 가능성, 소량생산 등으로 인해 위조 전자부품이 유입되어 무기체계의 신뢰성 저하를 유발시킬 가능성이 가중되고 있다. 본 논문은 개발이 완료되어 양산중인 무기 체계를 대상으로 위조 전자부품 검증을 위한 구체적인 식별기준을 도출하고, 다양한 식별 및 검증방안을 제시한다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제16권11호
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• pp.1116-1120
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• 2010

본 논문에서 우리는 추천 시스템을 위한 두 개의 정제된 이웃선정 알고리즘을 제시하고, 또한 아이템의 속성정보가 어떻게 고품질의 예측을 위해 사용될 수 있는지를 보인다. 정제된 이웃선정 알고리즘은 가상 이웃과 대체 이웃을 각각 사용하여 이행적 유사도를 기반으로 한 이웃선정 방법을 적용한다. 실험 결과는 본 논문에서 제안한 알고리즘을 적용한 추천 시스템이 다른 시스템에 비해 보다 우수한 성능을 가짐을 보여준다. 이러한 제안 시스템은 예측 품질의 저하 없이 대규모 데이터셋 문제 및 초기 참여자 문제를 극복할 수 있게 한다.

• 제어로봇시스템학회논문지
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• 제19권1호
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• pp.27-33
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• 2013

Nowadays, the utilization of renewable energy sources like wind energy is considered one of the most effective means of generating massive amounts of electricity. This is evident in the rapid increase of wind farms all over the world which comprise a huge number of wind turbines. However, the drawback of utilizing wind turbines is that it requires maintenance, which could be a costly operation. To keep the wind turbines in pristine condition so as to reduce downtime, the implementation of CMS (Condition Monitoring System) and FDS (Fault Detection System) is mandatory. The efficiency and accuracy of these systems are crucial in deciding when to carry out a maintenance process. In this paper, a fault detection system based on intelligent clustering method is proposed. Using SCADA data, the clustering model was trained and evaluated for its accuracy through rigorous simulations. Results show that the proposed approach is able to accurately detect the deteriorating condition of a wind turbine as it nears a downtime period.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.289-292
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• 2002

This paper provides a frame-layer method for controlling bit rate of compressed video data in real time. Our approach is easy to operate and can store encoded video data in real time without deteriorating the quality of an image. To provide ameliorated and consistent visual quality, a new concept named SOP (Set Of Pictures) and a new quantization parameter variation control algorithm based on a second-order rate-distortion model 〔2〕 are introduced. The total bit-budget is allocated efficiently to cope with unpredictable recording time by using the proposed algorithm and it is distributed to each frame. In the end, we show improved and consistent video quality with experimental results obtained from C-model of a MPEG-4 (simple-profile) encoder.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.687-689
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• 2004

As using of network increases rapidly, performance of system has been deteriorating because of the overhead and bottleneck. Nowadays, High speed I/O network standard, that is a sort of PCI Express, HyperTransport, InfiniBand, and so on, has come out to improve the limites of traditional I/O bus. The InfiniBand Architecture(IBA) provides some protocols to service the applications such as SDP, SRP and IPoIB. In our paper, We explain the architecture of IPoIB (IP over InfiniBand) and its features in channel based I/O network. And so we provide a performance evaluation result of IPoIB which is compared with current network protocol. Our experimental results also show that IPoIB is batter than TCP/IP protocol. For this test, We use the dual processor server systems and Linux Redhat 9.0 operating system.

• 대한안전경영과학회지
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• 제12권1호
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• pp.179-188
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• 2010

Competitive capacities in terms of price are rapidly deteriorating since the 1990's due to the competition and rapid pursuit of surrounding nations, exchange rates, increased wages, and labor and management disputes etc. Therefore, this paper shows the significant contents of preceeding research, surveys the employees of small and medium manufacturers who implemented the Toyota production system to conduct various analyses to determine the effect of the operation achievements so as to propose methods to effectively implement the Toyota manufacturing system and maximize long term operational achievements.