• 디지털산업정보학회논문지
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• 제5권2호
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• pp.87-93
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• 2009

In this paper, we propose and evaluate the availability of single sensor node using a hierarchial modeling approach. We divides a sensor node into a software and hardware and analyze failures of each component. We construct Markov chains to represent the components of a sensor node, and then we construct a hierarchical model which use fault tree in upper level and Markov chains in lower level. We evaluate the availability and down of single sensor node.

• 한국시스템다이내믹스연구
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• 제11권2호
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• pp.119-138
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• 2010

This study introduces the system dynamics model that simulate total operational availability when 10 equipments made of 3 major components are serviced under the constrains of the maintenance capacity level and the number of spare parts. This simulation is designed on the base of reliability engineering concept so failures of components happens with the rule of engineering factors like the mean time between failure(MTBF) of component and the next failure time of one component is effected by the conditions of other components. We analysed availability of 10 equipments under 121 constrains and executed multiple regression analysis with the simulation result. The analysis provide the managerial insight in the service fields with operation many equipments.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권2호
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• pp.110-117
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• 2016

Purpose: Biswas and Sarkar [11] found the availability of a system maintained through several imperfect repairs before a replacement is allowed. However they missed a part of coefficients in the integration. This paper corrects the erratum of Biswas and Sarkar [11] and performs the reliability analysis incorporating the optimal number of imperfect repairs. Methods: To find the singularities and residues of the suitable complex-valued function for the availability, the computer package Matlab is used. Also the performance measures are calculated by defining and assigning costs. Results: The accurate availability functions with respect to the numbers of imperfect repairs and the optimal number of imperfect repairs before a replacement are obtained. Conclusion: The reliability for a system under imperfect repair before a replacement is analyzed using Fourier transform technique.

• 한국군사과학기술학회지
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• 제21권4호
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• pp.520-528
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• 2018

This paper studies the optimal inventory levels of Korea Assault Amphibious Vehicle(KAAV)'s assemblies in order to assure the required operational availability. The simulation model is built and implemented for the impact of the inventory levels on operational availability. Using regression analysis and integer programming, the optimal inventory levels of essential assemblies are suggested and analyzed. Finally, sensitivity analysis is conducted with recycling maintenance delay time.

• 한국생활과학회지
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• 제23권1호
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• pp.15-29
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• 2014

The purposes of this study were to explore the effect of mother-child emotional availability on preschooler's preschool adjustment and mediating effect of preschooler's effortful control on the relationship between mother child emotional availability and preschooler's preschool adjustment. 222 preschoolers(110 boys, 112 girls, aged 5) and their mothers participated in this study. Mother child emotional availability was assessed by Emotional Availability Scale(Biringen, et al., 1998). Preschooler's effortful control was measured by the Child Behavior Questionnaire(Rothbart, et al., 1994). Preschooler's school adjustment was measured by Teacher Rating Scale of School Adjustment: TRSSA(Buhs & Ladd, 2001). Data were analyzed using descriptive statistics, correlations, and structural equation modeling analysis. The major results of this study were as follows; First, Mother-child emotional availability effected on preschooler's preschool adjustment. Second, Mother-child emotional availability effected on preschooler's effortful control. Third, Preschooler's effortful control effected on preschooler's preschool adjustment. Forth, preschooler's effortful control mediated the effect of mother-child emotional availability on preschooler's preschool adjustment. That was, the more mother-child were emotionally available to each other, the more preschooler's effortfully control their attention and behavior, which in turn contributed to preschooler's preschool adjustment. In conclusion, mother-child emotional availability affect on preschooler's preschool adjustment and preschoolers control mediates the relationship between mother-child emotional availability and preschool adjustment.

• 한국정보통신학회논문지
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• 제18권11호
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• pp.2634-2639
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• 2014

시스템 및 네트워크의 안정적인 서비스를 위한 기본적인 구조로 다양한 이중화 방식이 있다. 또한 시스템 및 네트워크의 성능을 분석하기 위하여 페트리네트에서부터 Stochastic Reward Net(SRN)에 이르기까지 다양한 성능 분석 모형이 존재한다. 본 논문에서는 정상 상태에서 하나의 액티브 서비스 유닛과 하나의 스탠바이 서비스 유닛을 가진 2N 이중화 방식을 SRN으로 모형화 한다. 성능 분석 소프트웨어인 추계적 페트리네트 패키지 SPNP를 사용하여 2N 이중화 방식의 가용도를 분석한다.

• 한국시스템다이내믹스연구
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• 제12권1호
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• pp.115-130
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• 2011

This study shows the operational availability(Ao) analysis of the supply chain with maintenance functions using the system dynamics simulation. The simulation uses 60 equipments which are serial systems composed by 4 major components. And every entities are connected each other by causal loops. So whole simulation executed like one organic system. Specially we consider 2 constraints, one is the number of spare parts and the other is maintenance capacity level. 2 constraints have 11 levels each so the simulation has 121(11*11) scenarios which scenario has 30 different random number seed. The simulation executed total 3,630(11*11*30) times. We analysis average Ao of total equipments by 121 scenarios and additionally the regression of the average Ao and 2 constraints. As the result, we can get the more accurate values by the system dynamics simulation than the regression to analysis complex system like the supply chain with maintenance functions.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.1049-1057
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• 2011

Today, most weapon systems operate as component systems of SoS(System of Systems) and they produce synergy effects in the battle field by interoperating. In addition, the acquisition issues on weapon systems have expanded into SoS context including sustainment analysis. Availability is the sustainment KPP(Key Performance Parameter) of weapon systems. In this paper, a simulation model is proposed to analyze the availability of SoS. The simulation model consists of 5 modules: Mission and Task, System, System RBD, Maintenance system and a simulation engine. Then it was implemented and applied to a SoS. As a result of the application, the simulation model could be applied for analyzing the availability of the SoS and provided information about critical tasks and risky component systems to complete the given mission of the SoS.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2545-2548
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• 2003

Reliability is the very important issue for nuclear fields. In this paper, an analysis method is suggested to evaluate the level of availability improvement by adding the fault diagnosis function in the control system of Reactor Protection System. The Failure Mode Effect Analysis(FMEA), MIL-HDBK-217F, and Makov modelling techniques are used for availability assessment.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.505-510
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• 1996

A simple model for RAM (Reliability, Availability and Maintainability) analysis and its computer code are developed for application to DUPIC fuel fabrication system. The approach is obtained by linking the allocation model (top-down method) to bottom-up method for RAM analysis. As a result, the availability requirement of subsystem, as well as the buffer storage requirement between processes, are evaluated for the DUPIC facility..