• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2000년도 춘계학술대회 발표논문집
• /
• pp.63-70
• /
• 2000

Brown and Proschan(1983) introduced a model for imperfect repair. At each feilure of a device, with probability p, it is repaired completely or replaced with a new device(perfect repair), and with probability 1 - p, it is returned to the functioning state, but it is only recovered to its condition just prior to failure(imperfect repair or minimal repair). In this paper, we limit the number of consecutive minimal repairs by n. We find some useful properties about ${\mu}$$\_$k/, the expected time between the k-th and the (k + 1)-st repair under the assumption that only minimal repairs are performed. Then, we assign cost to each repair and find the value of n which minimizes the long-run average cost for a fixed p under the condition that distribution F of the device is DMRL.

• 영어어문교육
• /
• 제18권3호
• /
• pp.53-75
• /
• 2012

The present study examined the role of language proficiency in dyadic discourse in the organization of repairs and the distribution of linguistic features contained in repairs. One native speaker of English and five non-native speakers participated and formed three dyads: one same-proficiency NNS-NNS (non-native speaker), one different-proficiency NNS-NNS, and one NS (native speaker)-NNS dyads. Results showed that overall repair patterns in this type of interaction were more conversational than didactic, and that the degree of difference in proficiency between the participants in the dyad influenced repair patterns and the distribution of linguistic features in relation to repair patterns. Also, discussed in the present paper are some implications of the results and other issues related to language learning.

• International Journal of Reliability and Applications
• /
• 제4권1호
• /
• pp.27-40
• /
• 2003

Maintenance models involving minimal imperfect repair frequently appear in the literature of reliability and operations research. Most of the literatures concerning the stochastic behavior of repairable systems assume that it takes negligible time to repair a failed system and so the length of repair time does not affect the maintenance strategy. It is more realistic to consider the length of repair times in developing maintenance model, however. In this paper, we consider an imperfect repair model with random repair time and investigate some stochastic properties of the number of perfect repairs and the number of minimal repairs. Also we derive the expressions for evaluating the expected numbers of perfect and minimal repairs in general and apply these formulas for certain parametric life distributions.

• 호남수학학술지
• /
• 제23권1호
• /
• pp.145-158
• /
• 2001

In this paper we investigated a replacement model with two types of repairs. Repairs are classified into minimal and perfect repair. An operating unit is completely replaced whenever it reaches age ${\tau}({\tau}>0)$(planned replacement). If it fails at age $t<{\tau}$, it is either restored by a entire unit with probability p(t)(perfect repair), or it undergoes minimal repair with probability $\bar{p}(t)=1-p(t)$. After a planned replacement, the procedure is repeated.

• 대한산업공학회지
• /
• 제4권1호
• /
• pp.1-3
• /
• 1978

This paper presents a model for determining the optimal number of minimal repairs before replacement. The basic concept parallels the periodic replacement model with minimal repair at failure introduced by Barlow and Hunter, only difference being the replacement signalled by the number of previous minimal repairs performed on the unit. In the case of Weibull distribution, which is widely used as a general failure distribution, the optimal solution could be obtained numerically and seems more cost effective compared to the Barlow and Hunter's Policy II.

• 기술사
• /
• 제32권1호
• /
• pp.35-42
• /
• 1999

• 대한가정학회지
• /
• 제47권9호
• /
• pp.15-26
• /
• 2009

The main purpose of this study was to speculate how psychological state of adolescent students has changed their school uniform style. For the study, the distinctive characteristics during adolescence stage were theoretically examined. Through the examination, this study found four interests in fashions and school uniforms. For the purpose, this study conducted interviews with grade 2 students in a total of six coeducation secondary schools in Seoul, Gyeongki and Gwangju using a questionnaire. The survey period ranged from December 15 2008 to December 24 2008 and a total of 1196 were used for a final analysis. This study extracted factors as Principal Components Analysis and used Varimax for orthogonal rotation analysis. To measure confidence, it used Cronbach's a test to item internal consistency. For data analysis, it used SPSS WIN 12.0 and for hypothesis analysis, frequency analysis, cross analysis, independent t-test, and one-way ANOVA were conducted. For posterior analysis, it used Sheffe test. The results are as follows: First, the interests in fashion and school uniforms differed depending on their own tastes, but these interests were more influenced by environment around school. Secondly, the boy subjects were more aggressive towards repairs their uniforms than the girls, which suggested that boys had stronger desire to show themselves to others and more satisfaction from repairs their uniforms than the girls. Based on the results, this study concluded as follows: We should pay attention to preventing deformation in original design of school uniforms while expanding options to have variable designs or to change detailed part of design. So, there will be no additional uniform mending expense and financial loss to parents, and students will be more satisfied with their school uniforms.

• 한국건설관리학회:학술대회논문집
• /
• 한국건설관리학회 2001년도 학술대회지
• /
• pp.495-500
• /
• 2001

공동주택은 준공 후 일정기간이 경과하면서 사용된 자재의 내구연한에 따라 노후화 현상이 나타난다. 구성자재의 내구연한에 의해 일부부위는 짧은 시간내에 수선을 하여야 하며 어떤 부위는 장시간이 경과한 후에 수선을 하기도 한다. 이와 같이 건물에 나타나는 다양한 노후화 현상에 대해 체계적일 유지관리를 하려면 준공후 경과년수에 따른 장기적인 계획수선을 필요로 한다. 장기수선계획작성에는 건물의 공종에 따른 수선시기를 예측하여 이를 기초로 작성해야 한다. 공동주택에서 장기수선계획이 계획에 지나지 않으며 실질적인 수선에 적용되지 못하는 주요인은 앞으로 수선이 예측되는 건물의 각 부위에 대한 수선시기를 예측하지 못하기 때문이다. 이에 본 연구는 전국에 산재한 공동주택을 장수명화하기 위해 장기수선계획을 활용하여 .해당단지의 부위별 재료의 특성을 반영한 수선주기 및 수선시기를 예측하고, 공동주택 관리자가 주기적 점검, 진단, 교체 등의 사항을 유지관리 캘린더에 의해 단지별로 자동관리할 수 있는 웹기반 유지관리 시스템을 제안하다.

• 대한치과기공학회지
• /
• 제33권1호
• /
• pp.25-35
• /
• 2011

Purpose: There are some advantages of the acrylic resin denture base ; appropriate strength, volume safety, simple processing apparatus, and low cost. But, it have a weakness for fracture by intense pressure or shock. However, the repairs for resin denture base are possible using various materials and techniques. There is a few studies in repairs for resin denture base, but not clinical researches. And there is no studies in absorbed saliva into the region of fracture and bond strength. This study is to observe re-bond strength of resin denture base after repairing under saliva absorption. Methods: The samples were made of heat curing resin and the rectangular parallelepiped specimens which were 50mm long, 10mm wide and 3mm high. The four different groups immersed in the artificial saliva for 2 weeks were prepared, 1) no repaired control samples, 2) immediately repaired samples, 3) repaired samples after 1 day dry, and 4) repaired samples after 3 days dry. The prepared samples were repaired by two different curing materials, self curing resin and heat curing resin method. Each groups composed of 10 specimens were experimented with the three point bending tests for bonding strength measuring Results: There were under condition absorbed in the artificial saliva and repaired by self curing resin method, repaired specimens after 1 day and 3 days dry groups had higher values of bonding strengths than control group, and bonding strengths of immediately repaired samples were similar to those of control samples (p<0.05). There were under condition immersed in the artificial saliva and repaired by heat curing resin method, immediately repaired samples showed similar values to bonding strengths of control groups, and repaired samples after 1 day and 3 days dry groups were lower than those of control group (p>0.05). Conclusion: In this study, the repairs for resin denture base were remarkably high values of bonding strengths than those of the past, and showed that have stable bonding strengths independent of saliva absorption of denture base, so present repairs for resin denture base can be performed, regardless of saliva conditions.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
• /
• pp.250-253
• /
• 2001

Recently, based on the smart structure concept, optical fiber sensors have been increasingly applied to monitor the various engineering and civil structural components. Repairs based on adhesively bonded fiber reinforce composite patches are more structurally efficient and much less damaging to the parent structure than standard repairs based on mechanically fastened metallic patches. As a result of the high reinforcing efficiency of bonded patches fatigue cracks can be successfully repaired. However, when such repairs are applied to primary structures, it is needed to demonstrate that its loss can be immediately detected. This approach is based on the "smart patch" concept in which the patch system monitors its own health. The objective of this study is to evaluate the potentiality of application of transmission-type extrinsic Fabry-Perot optical fiber sensor (TEFPI) to the monitoring of crack growth behavior of composite patch repaired structures. The sensing system of TEFPI and the data reduction principle for the detection of crack detection are presented. Finally, experimental results from the tests of center-cracked-tension aluminum specimens repaired with bonded composite patch is presented and discussed.