• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.593-602
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• 2004

We have developed a digital control rod control system not only to improve its performance but also to improve its reliability and speed of response so that it can replace the old fashioned analog system. However, a new developed digital control system should be tested to prove the validity by using any prototype or mock-up before application. The reliability prediction and the reliability block diagram analysis methods were adopted to verify the reliability of the developed hardware. For the case of software, especially fur a new developed control algorithm it has been tested to prove performances and validation by using a dynamic simulator and mock-up of control rod drive mechanism altogether. Here we want to present some key factors regarding to the new developed digital system with some verification procedures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.269-275
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• 2020

RAM of elements to support weapon systems is conducted at the initial development phase and standard is suggested to accomplish strategy requirement performance from a design spec. Operational availability is a key point of the military's ability to ensure combat readiness and to win the battle. In the weapon system development phase, operational availability is used as a development standard. The military provides ALDT, operation and standby time, which are elements of operational availability. ALDT is a key element of operational availability that must be maintained for combat readiness, as it depends on the aging of a weapon system, maintenance policies and geographical conditions. Operational Availability to be set at the development phase has many differences from the operational availability that is analyzed in the actual operational phase because ALDT is applied as a simple assumption. In the paper, we analyzed ALDT applying the decision tree method through failure data acquired from initial operation. Through this study, we have devised the optimal ALDT setting method to achieve operational availability about operation when the weapons system is unstable.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.2
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• pp.168-175
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• 2020

Failure of essential avionic equipments have a significant impact on the operations and safety of P-3 maritime patrol aircraft. Therefore, avionic equipments of P-3 are required to have higher reliability. Based on the field failure data, this paper studies the reliability growth of essential avionic equipments in P-3 using Duane model. Additionally, a simulation model is built and implemented for identifying the operational availability according to the field failure data of avionic equipments.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.3-3
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• 2019

최근 기후변화로 인한 집중호우, 가뭄 등 예측하기 어려운 사태가 발생하면서 깨끗하고 안정적인 용수공급 기술의 필요성이 대두되고 있다. 이에 IoT와 기존 물관리시스템을 결합한 스마트워터그리드 출범은 실시간으로 수요와 공급량의 정보를 취득하여 물 관리 효율성을 제고 할 수 있게 되었다. 실시간 수요량 자료를 이용하여 물 수요량 예측을 통한 최적의 물 공급량을 결정할 수 있다. 이 때 스마트워터그리드의 핵심 기술은 실시간으로 취득한 자료의 품질관리라 할 수 있다. 본 연구 대상지역인 영종도 112 블록에는 528개 AMI 스마트 미터를 이용하여 1시간 단위의 물 수요량 자료를 원격 검침하고 있다. 각 수용가에 설치된 AMI 센서를 통해 수집된 자료에는 오류를 포함할 수 있는데 통신 장애, 미터기 고장 및 교체 등으로 발생된다. 결측된 수요량 자료는 상수관망 수리해석에 사용되는 기본자료로서 비표본오차를 증가시켜 검정력과 정확성을 결여시키는 문제가 있다. 이에 본 연구에서는 수집된 자료를 가용할 수 있는 자료로 정제하고 대체하기 위해 완전히 관찰된 자료(complete data)만을 이용하여 각 시간에 따른 관경별, 용도별 그리고 요일별 수요패턴을 추정한다. 결측된 자료는 기존에 사용되는 평균대체법과 핫덱 대체(hot deck imputation) 등과 비교 검증한다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.66-75
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• 2016

Due to aggressive scaling of device sizes and reduced noise margins, physical defects caused by aging and process variation are continuously increasing. Additionally, with scaling limitation of metal wire and the increasing of communication volume, fault tolerant method in manycore network-on-chip (NoC) has been actively researched. However, there are few researches investigating reliability in NoC with voltage-frequency-island (VFI) regime. In this paper, we propose a table-based routing technique that can communicate, even if link failures occur in the VFI NoC. The output port is alternatively selected between best and the detour routing path in order to improve reliability with minimized hardware cost. Experimental results show that the proposed method achieves full coverage within 1% faulty links. Compared to $d^2$-LBDR that also considers a routing method for searching a detour path in real time, the proposed method, on average, produces 0.8% savings in execution time and 15.9% savings in energy consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.357-364
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• 2014

In this paper deals with PON Remote monitoring solution using Reflecting Filter. The current FTTH-PON can not be monitored in real time that Optical cable fault and Quality degradation of Splitter. To solve this problem, Monitoring can make Feeder Network and Splitter that Reflecting filter development using the basic structure of Fiber Bragg grating. Reflecting Filter is Quality Monitoring System shall provide tools for user to view and analyze degradation of cables and splitter in particular predict any gradual component degradation(Optical cable bending, splice, connector, etc) before it becomes service impacting. The Reflecting Filter solution is splitter down and confirm the fault location of optical cable and it will send central control station can be monitored system an alarm to the OLT. In other words, wavelength side branches Mating existing communication affairs (Coupler) using the core of one optical wavelength for live monitoring two wavelengths and sends the subscriber side modem and aggregation switch device remotely using a reflective optical line filter monitoring the study of the system. this study can development of Reflecting filter improve the average processing time of Optical cable fault and efficient Maintenance of the network.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.239-246
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• 2004

Accelerated degradation test (ADT) can be a useful tool for assessing the reliability when few or even no failure are expected in an accelerated life test. In this paper, MLCC (Multilayer Ceramic Capacitors), a sort of passive components which have large capacitance(X7R -55$^{\circ}C$~1$25^{\circ}C$) have been tested, and least-square analyses are used to illustrate our approach in which amount of degradation of a DUT following log-normal distribution. We assumed a simple and useful linear model to describe the amount of degradation over time subjected to different voltage levels applied. Tests for linearity of the performance-time relationship, and provide tests for how well the assumptions hold. Also, by using Eyring Model, MLCC's mean life time is assessed.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.520-526
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• 2007

본 논문에서는 한국형 틸팅열차의 유지보수 활동을 위해 신뢰성기반유지보수체계를 제안하였다. 열차시스템을 3단계의 교체 부품 단위로 분류하고, 각 단위에 대해 기능블록도를 작성한 후 고장모드 영향 분석을 실시하였다. 각 단위의 심각도를 결정한 후 유지보수 정책을 제안하였으며, 틸팅열차를 위한 유지보수 기준을 정하고, 실제 사례를 제시하였다. 제안된 신뢰성기반유지보수체계는 기존 유지보수 체계와도 호환성을 갖고 있으며, 안전성 향상과 유지보수 활동 효율화에 기여할 수 있다.In this paper, a reliability centered maintenance (RCM) system is proposed to perform maintenance action for Korean Tilting Train. The train system was divided into line replaceable units up to three steps. Functional block diagrams were drawn and failure mode effect analysis for the units was carried out. The criticality of each unit was determined and a maintenance policy was proposed. Maintenance and repair criteria for the tilting train were determined and an example was presented. The proposed RCM system is compatible with the previous maintenance system and contributes to improvement of safety and efficiency of maintenance action.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.3
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• pp.397-404
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• 2011

In this research, wish to suggest method to embody system that can accommodate defect of PLC and find actual propriety. Defect permission control system minimizes production damage because enables repair and checking without discontinuance and improve believability about whole system. Propose duplexing of system to embody this fault tolerant system. Therefore, composed control system that can permit defect or breakdown duplexings of various module proposing this system, and confirms to simulation and actuality kiln of defect permission control system through an application experiment, and compares for mean time between defect by estimate and defect special quality and system configuration of failure(failure) to improve believability of PLC control system together. In proposed system expression method and system mode and relation with operation mode, error discovery mode and switching tube of duplexing mode, and PLC's central processing unit of node study algorithm about master-standby conversion driving and continuous operation of 2 channels method that have 2 that is not one and deduced continuous operation method and result about defect permission in this algorithm and applies this result to actuality kiln control system and confirms continuous operation about PLC defect permission.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.88-95
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• 2018

Maintainability indicates how easily a system can be restored to the normal state when a system failure occurs. Systems developed to have high maintainability can be competitive due to reduced maintenance time, workforce and resources. Quantification of the maintainability is possible in many ways, but only after prototype production or with historical data. As such, the graph theory and 3D model data have been used, but there are limitations in management efficiency and early use. To solve this problem, we studied the maintainability index of weapon systems using SysML-based modeling and simulation technique. A SysML structure diagram was generated to simultaneously model the system design and maintainability of system components by reflecting the maintainability attributes acquired from the system engineering tool. Then, a SysML parametric diagram was created to quantify the maintainability through simulation linked with MATLAB. As a result, an integrated model to account for system design and maintainability simultaneously has been presented. The model can be used from early design stages to identify components with low maintainability index. The design of such components can be changed to improve maintainability and thus to reduce the risks of cost overruns and time delays due to belated design changes.