• 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 & 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.

A Study of Information System Availability Guarantee Methods and Application

  • Kim, Hee Wan
    • International Journal of Advanced Culture Technology
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    • v.8 no.3
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    • pp.292-299
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    • 2020
  • This paper presents an evaluation criteria of an information system availability for guaranteeing availability (service target level) from the perspective of the SLA contract and its technical point of view. In order to verify the effectiveness for information system failure and availability guarantee measures, three cases were examined. In summary, the failure time was reduced by 32% ~ 62% after applying the availability guarantee measure, verifying the excellence in the evaluation of an information system availability.

A Study on the Assessment Measures for Availability of Information Assets (정보 자산에 대한 가용성 평가 방안에 관한 연구)

  • Kim, MinSu;Lee, Byoungcheon
    • Convergence Security Journal
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    • v.20 no.2
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    • pp.53-58
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    • 2020
  • In this study, it suggests the High Availability (HA) implementation plan of building a continuous service infrastructure as a strategy ensuring availability, as the importance of availability securing corporate business continuity emerges in the knowledge and information society. However, if the reliability of the criticality assessment of information asset is not ensured, it requires assessment measures for availability that can be managed by mapping with service maintenance assessment items, which are availability criteria based on the asset criticality evaluated through the asset value matrix because it is difficult to maintain security in conjunction with the value of real assets. Therefore, this study suggests the assessment measures for availability of information assets.

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.

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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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 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.

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.