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결함유형에 따른 소프트웨어 신뢰도와 소프트웨어 상품화 최적 시기 전략
김영휘,이완형,Kim Yeong-Hwi,Lee Wan-Hyeong 한국국방경영분석학회 1990 한국국방경영분석학회지 Vol.16 No.2
This paper classifies faults into three types : simple, degenerated, and regenerated faults. This paper also deals with the characteristics of each type of fault to determine the software reliability based on the assumption; i. e., a system consisting of several subsystems (modules) which may be debugged simultaneously. For each type of fault, several formulas are developed to obtain the failure rate and the expected number of failures found during debugging. A model is developed based on the formulas of the failure rate and the expected number of failures to decide the optimal release time of a new software: minimizing the total cost with constraints restricting to the failure rate of each module in the software. By using this model, optimal release times are found for some cases; the eliminated faults are assumed simple faults only, regenerated faults only, simple and degenerated faults, and so on.
김영휘,하석태,Kim Yeong-Hwi,Ha Seok-Tae 한국국방경영분석학회 1989 한국국방경영분석학회지 Vol.15 No.1
This paper deals with the mission effectiveness of an airfleet, Airfleet operating system consists of a finite number of units performing the several mission types. Earlier works for the mission effectiveness of a fleet is limited to only one mission type and computer simulation approaches. The mission effectiveness. model of a fleet is constructed by three attributes - the mission readiness of the units, the mission reliability and capability of units. The environmental conditions and human factors affecting the mission success are considered together. The solution of the model is obtained by analytical technique. Especially, AOS is considered a closed queueing network with a finite number of units and a single job class. And then, the mission readiness of the units is found by the mean value analysis. The model would be a useful tool to readily evaluate mission effectiveness of a airfleet as it is and provide a criterion for determining the optimal operating policy.
전력계통 운용상태의 신속한 판단을 위한 정보수집 및 추론기법
김영휘(Young-Hwi Kim) 산업기술교육훈련학회 2008 산업기술연구논문지 (JITR) Vol.13 No.4
This paper presents an information collection and a novel inference technique for evaluation of power system operation state. In most developing countries, power demands are steadily increasing and consequently power systems are becoming larger and more complicated. In addition, power system deregulations further complicate the power system operational tasks, which are resulted in prevailing wide area blackouts worldwide. In this paper, we proposed an effective information collection and operating state evaluation methods using a knowledge-based system. The RTS-79 24 bus system is used as a test system. The power system model is composed with JESS templates and included in the knowledge-base as a part of fixed facts. Dynamic informations are collected from various analysis results and actual operational data. Inferences are performed with rules expressed with terms in different abstraction levels. Future research will be concentrated on intelligent contingency selections for preventing wide area blackouts.
피난 시뮬레이션과 BIM모델을 활용한 경전철 역사 내의 ‘시설물 내 대피시설’ 위치 선정에 대한 연구
김영휘(Kim Younghwi),이진영(Lee Jinyoung),Yuan Tianfeng,윤영수(Yoon Youngsoo) 한국방재학회 2018 한국방재학회지 Vol.18 No.4
우리나라는 세계 유일의 분단국가로서 발생 가능한 잠재적인 위험에 대해 사전에 대비하고 준비할 필요성이 있다. 이러한 상황에서 단순히 대피시설의 수를 늘리기보다는, 기존 시설물을 활용하여 평상시에는 일반 용도로 사용되나 CBRE 상황에서는 대피시설로서의 기능을 할 수 있는 SIP를 확립하고 관리할 필요가 있다. 따라서 본 연구에서는 BIM 소프트웨어를 이용하여 경전철 역사를 모델링하고, 각 공간의 접근성과 수용성을 고려한 피난 시뮬레이션을 실시하여, 역사 내에 SIP의 최적 위치를 선정하는 과정을 제시하였다. 본 연구에서 제안된 과정은 직접적인 시뮬레이션을 통한 합리적인 인간 행동 분석에 기초한 것이기 때문에, 기존의 사회기반시설에 적용된다면 CBRE 상황 발생 시 더욱 안전하고 신속한 대피가 가능할 것으로 기대된다. As the only divided country, preparing for possible risks is to be considered in Korea. In these circumstances, rather than just increasing the number of evacuation facilities, it is needed to establish and manage SIP, the space that is used for its original purpose in normal situation but can be utilized as a shelter during CBRE situation. Therefore, in this study, light rail station is modeled by using BIM software and the process of selecting the best location of SIP in the station by performing several simulations accordance with various escape scenarios was presented. Since the process proposed in this study is based on rational analyses of human behavior through direct simulations, if applied to various infrastructures, it is expected for people to evacuate fast and safely under CBRE situation.
김영휘(Young-Hwi Kim) 산업기술교육훈련학회 2007 산업기술연구논문지 (JITR) Vol.12 No.3
The deadtime of the inverter are to reduce the amplitude of fundamental frequency component, to generate low harmonics and to make the error of load power angle. And the factors to induce the deadtime are directions of load current, load power angle, modulation index, modulation frequency, and etc. The methods to reduce the deadtime effects are reference modification method to apply the sinusoidal PWM and logical combination method to apply the memory-based PWM. In the methods, the current feedback is necessary. In this thesis, to minimize the deadtime effects of 3 phase inverter, the compensation method to design the gating logic circuit is suggested and implemented. The results showed the reduced magnitude of the 5th, 7th and higher harmonics and the increased output average voltage than that of the traditional compensation methods.