• Title, Summary, Keyword: Availability

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Availability Measures for Repairable Dynamic Reliability Models (수리 가능한 동적 신뢰도 모델의 가용도 척도)

  • Choi, Sung-Woon
    • Journal of the Korea Safety Management and Science
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    • v.8 no.5
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    • pp.253-264
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    • 2006
  • This paper is to derive three reliability and eight maintainability measures after organizing total time. I propose inherent availability,.achieved availability and operational availability with the new and useful reliability and maintainability measures above. Especially, inherent availability measure extends the repairable system reliability models.

Study on the Thermodynamic concept of "Availability" in Energy Conservation (에너지 절약을 위한 "유용성"(Availability)의 열역학적 고찰)

  • Son, Byeong-Chan
    • Journal of the Korean Society for Quality Management
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    • v.14 no.2
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    • pp.33-39
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    • 1986
  • This paper is to present basic concepts of availability, irreversibility, dead states, its relationship to other thermodynamic functions, and the history of availability. The balance of availability and effectiveness has also been formulated in order to build basis on which further study and actual application of availability in estimation of available energy are to be thought.

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On the Steady State Availability of Age-Dependent Minimal Repair Model

  • Cha, Ji-Hwan;Kim, Jae-Joo
    • 한국데이터정보과학회:학술대회논문집
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    • pp.17-22
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    • 2002
  • Availability is an important characteristic of a repairable component. Iyer(1992) obtained the 'limiting efficiency'(not the `steady state availability') of the age-dependent minimal repair model which was first considered by Block et al.(1985). However the existence of the steady state availability of the model has not been reported. In this note, the existence of the steady state availability of the model is shown and a brief remark on the importance of the property is given.

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Some Results on Availability of Repairable Component and Repairable Coherent System

  • Cha, Ji-Hwan
    • Communications for Statistical Applications and Methods
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    • v.10 no.1
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    • pp.191-202
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    • 2003
  • Availability is an important measure of performance of a repairable component. In this paper, the explicit expression for the availability of a repairable component, which is subject to the policy II(Age Replacement Policy) of Barlow and Hunter (1960), is obtained and the existence of the steady state availability is shown. The steady state availabilities of the model are also obtained for the cases when the mean of the minimal repair time is increasing at a geometric rate or linearly increasing, In order to show the importance and the utility of the obtained result, we also consider an illustrative example of the repairable coherent system whose components are repairable, and the obtained results are applied to derive the steady state availability of the whole system. In this situation, we can see that the condition of the existence of the steady state availability for each component is essential. Some remarks on the optimal replacement policy that maximizes the steady state availability are also given.

A Study on the Determination of Replacement Time for Military Vehicle Using Availability Analysis ­ Focused on 2 \frac{1}{2} Ton Cargo­ (군용 기동장비의 가용도 분석을 통한 교체시기 결정에 관한 연구 ­2 \frac{1}{2} 톤 차량을 중심으로­)

  • 하형호;강성진
    • Journal of the military operations research society of Korea
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    • v.29 no.2
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    • pp.81-99
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    • 2003
  • This paper propose a method determining life cycle for military vehicle using availability analysis. Many studies determining life cycle for military equipments have been done recently However, those studies focused on economic life such as average system cost method, equivalent annual cost method and cumulative operations cost method. In many case, those results are not appropriate in deciding replacement in the field situation, we consider an effective life cycle method using availability concept. In order to determine an equipment life cycle. Two kinds of availability is considered. One is equipment yearly availability, the other is operational availability with operating distance per year. The life cycle is determined by achieving unit target availability level. The result using this concept for K­511 military vehicle life cycle is about 19 years, which is longer than previous studies.

High Availability Web Server Cluster Using Self-healing Technique (자가 치유 기법을 이용한 고가용도 웹 서버 클러스터)

  • Chung, Ji Yung;Kim, Young Ro
    • Journal of the Korea Society of Digital Industry and Information Management
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    • v.5 no.1
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    • pp.23-32
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    • 2009
  • Although the web is becoming a widely accepted medium, it provides relatively poor performance and low availability. A cluster consists of a collection of interconnected stand-alone computers working together and provides a high-availability solution in application area such as web services or information systems. Web server clusters require a high-availability service with a proactive and practical fault management. However, as the system complexity grows, it is not easy to meet the requirement. Therefore, web server clusters must have self-fault management capability for meeting high-availability requirement. In this paper, we propose high availability web server clusters using self-healing technique with a minimal human intervention. Our experimental results show that a proposed method can be used to improve the availability of web server clusters.

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ANALYSIS ON THE AVAILABILITY OF COMS GS

  • Park, Durk-Jong;Lim, Hyun-Su;Ahn, Sang-Il
    • Proceedings of the KSRS Conference
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    • v.1
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    • pp.212-215
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    • 2006
  • This paper describes several reliability models to estimate COMS ground segment availability and shows assessed availability according to GS function. Due to a back-up concept among three ground center, SOC will have all H/W and S/W module to be installed in MSC and KOSC site. Therefore, all configurations and availability parameters for H/W and S/W modules in MSC and KOSC are assumed as equal with those in SOC, if related modules have same function. Prior to access availability over COMS GS function, Availability related to fundamental configuration such as series, parallel, partial operation, and module combined H/W and S/W is described. Consequently, all functions are expected to operate with more than 99% of availability.

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Mother-Child Emotional Availability and Preschooler's preschool adjustment: - Mediating effect of preschooler's effortful control (어머니-유아의 정서적 가용성과 유아의 유아교육기관 적응 - 유아 의도적 통제의 매개효과 검증)

  • Moon, Young Kyung
    • Korean Journal of Human Ecology
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    • v.23 no.1
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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.

System Availability Analysis using Markov Process (Markov Process를 활용한 시스템 가용도 분석 연구)

  • Kim, Han Sol;Kim, Bo Hyeon;Hur, Jang Wook
    • Journal of the Korea Society of Systems Engineering
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    • v.14 no.1
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    • pp.36-43
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    • 2018
  • The availability of the weapon system can be analyzed through state modeling and simulation using the Markov process. In this paper, show how to analyze the availability of the weapon system and can use the Markov process to analyze the system's steady state as well as the RAM at a transient state in time. As a result of the availability analysis of tracked vehicles, the inherent availability was 2.6% and the operational availability was 1.2% The validity criterion was defined as the case where the difference was within 3%, and thus it was judged to be valid. We have identified the faulty items through graphs of the number of visits per state among the results obtained through the MPS and can use them to provide design alternatives.

Assessing Throughput and Availability based on Hierarchical Clustering in Wireless Sensor Networks (계층적 클러스터링을 기반으로 하는 무선 센서 네트워크의 Throughput 과 Availability 평가)

  • Lee Jun-Hyuk;Oh Young-Hwan
    • Journal of Applied Reliability
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    • v.5 no.4
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    • pp.465-486
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    • 2005
  • A unreliable network system results in unsatisfied performance. A performance criterion of a network is throughput and availability. One of the most compelling technological advances of this decade has been the advent of deploying wireless networks of heterogeneous smart sensor nodes for complex information gathering tasks, The advancement and popularization of wireless communication technologies make more efficiency to network devices with wireless technology than with wired technology. Recently, the research of wireless sensor network has been drawing much attentions. In this paper, We evaluate throughput and availability of wireless sensor network, which have hierarchical structure based on clustering and estimate the maximum hroughput, average throughput and availability of the network considering several link failure patterns likely to happen at a cluster consisted of sensor nodes. Also increasing a number of sensor nodes in a cluster, We analysis the average throughput and availability of the network.

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