• International Journal of Reliability and Applications
• /
• 제12권2호
• /
• pp.103-116
• /
• 2011

A series-parallel system with independent but non-identical components is considered. The expressions have been derived for the joint reliability importance (JRI) of m (${\geq}2$) components, chosen from a series-parallel system. JRIs of components of two different series-parallel systems are studied analytically and graphically.

• Journal of applied mathematics & informatics
• /
• 제5권2호
• /
• pp.277-284
• /
• 1998

The reliability and an estimate for it are derived for series-parallel and parallel-deries stress-strength model under assumption that all components are subjected to a common stress. We also obtain the asymptotic normal distribution of the estimate.

• International Journal of Reliability and Applications
• /
• 제3권4호
• /
• pp.173-184
• /
• 2002

This paper introduces the joint structural importance of two components in a coherent system. Some relationships between joint structural importance and marginal structural importance are presented. It is shown that the sign of Joint structural importance can be determined, in advance, without computation in some special structures. The joint structural importance of two components in some series-parallel and parallel-series systems are established. Some practical examples are presented to elucidate some of the derived results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
• /
• pp.87-89
• /
• 2005

This paper proposes new series and parallel Sin+Cos PSS(power system stabilizer) for the purpose to improve the existing PSS1A's performance. The purpose of PSS is used to enhance damping of power system oscillations through injection of auxiliary signal for an excitation control terminal. The Proposed series and Parallel Sin+Cos PSS is connected adding the Sin+Cos terms additionally with serial and with parallel connection in a conventional PSS1A. The proposed controller is aim to considering of a damping of oscillation when it changes parameter fluctuations or operational load variations in a power system. The object of electric power system is KEPCO system and the voltage of power transmission line is a 154kV and a 345kV. The PSCAD/EMTDC package is used to authorize the effect of the proposed controller. Simulations were shown by and compared with the waveforms for frequency, voltage and electric power.

• 한국산학기술학회논문지
• /
• 제4권4호
• /
• pp.323-328
• /
• 2003

본 논문에서는 통신 기지국용 전원으로 사용할 수 있는 직렬 공진형 컨버터 시스템의 새로운 제어방식을 제안하였다. 주파수 제어 직렬 공진형 컨버터 시스템은 병렬 출력 직렬 공진(Parallel Output Series Resonant: POSR)형태이기 때문에 부하변동에 강인하다. 또한 스위칭 주파수를 제어함으로써 입력전압의 변화에도 안정된 출력을 제공한다. 실제 시스템 제작에 앞서 제안된 병렬 출력 직렬 공진형 컨버터 시스템의 분석을 하였고 ACSL(Advanced Continuous Simulation Language)을 이용한 모의실험을 하였다. 또한 실제의 시스템을 제작 및 실험을 통하여 시스템 특성을 확인하였다.

• International Journal of Reliability and Applications
• /
• 제9권2호
• /
• pp.153-165
• /
• 2008

This paper discusses the reliability equivalences of a series-parallel system. The system components are assumed to be independent and identical. The failure rates of the system components are functions of time and follow Weibull distribution. Three different methods are used to improve the given system reliability. The reliability equivalence factor is obtained using the reliability function. The fractiles of the original and improved systems are also obtained. Numerical example is presented to interpret how to utilize the obtained results.

• 전력전자학회논문지
• /
• 제13권2호
• /
• pp.110-118
• /
• 2008

기존의 저궤도 인공위성 전력계 시스템에 사용된 직렬 구조, 병렬 구조는 공전 주기 동안 두 번의 전력변환 과정을 거쳐 시스템의 효율을 감소시킨다. 직-병렬 구조는 한 번의 전력변환 과정을 거쳐 시스템의 효율을 향상시키지만 레귤레이터가 추가됨으로써 시스템의 비용과 무게, 크기를 증가시킨다. 본 논문에서는 레귤레이터의 추가 없이 시스템의 효율을 향상시키는 단순화된 직-병렬 구조를 제안한다. 인공위성이 지구를 공전하는 동안 상황에 따라 변화하는 제안한 구조의 동작을 네 가지 모드로 분류하고, 각 모드마다 제안한 시스템을 안정적인 동작을 확인하기 위하여 대신호 분석을 수행하였다. 실험을 통하여 기존의 직렬구조와 제안한 구조의 효율을 비교하였다. 제안한 구조의 안정적인 동작을 검증하기 위해 200W급 태양전지와 TMS320F2812 DSP로 제어되는 100W급 전력조절기 두 모듈을 병렬로 구성하여 실험하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제49권4호
• /
• pp.282-290
• /
• 2000

In this paper, the charge control with the input voltage feedback is proposed for the input series-output series-output parallel connected converter configuration for the high speed train power system application. This control scheme accomplishes the output current sharing for the output-parallel connected modules as well as the input voltage sharing for the input series connected modules for all operating conditions including the transients. It also offers the robustness for the input voltage sharing control according to the component value mismatches among the modules. And this configuration enables the usage of MOSFET for a high voltage system allowing a higher switching frequency for lighter system weight and smaller size. The performance of the proposed scheme is verified through the experimental results.

• 대한산업공학회지
• /
• 제1권2호
• /
• pp.51-56
• /
• 1975

A computer program for computing complex system reliability is described. The program is composed of three phases : Phase I program reduces all series, parallel and series-parallel components and subsequently obtains an irreducible non-series-parallel system. Phase II program enumerates all the possible paths from the source to the sink of the graph. Phase III program then computes system reliability based on the information obtained by the Phase II program. The program is based on a modified version of the algorithm published in [6]. An example of the use of the computer program is given.

• 한국산학기술학회논문지
• /
• 제7권6호
• /
• pp.1072-1077
• /
• 2006

본 논문은 AC 라인 리액터와 2개의 4레그 PWM 전압형 컨버터를 사용하여 병렬 및 직렬 능동필터 기능을 가지는 새로운 3상 Line-Interactive UPS 시스템을 제안하고 전압제어 방식을 설명한다. 제안하는 UPS 시스템의 병렬 및 직렬 PWM 전압형 컨버터에서 전압제어의 목적은 정상상태 및 과도상태에서 만족스러운 동작 특성을 보장하는 것이다.