• Smart Structures and Systems
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• 제22권2호
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• pp.151-159
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• 2018

Maintenance activities are regarded as a key part of the repairable deteriorating system because they maintain the equipment in good condition. In practice, many maintenance policies are used in engineering fields to reduce unexpected failures and slow down the deterioration of the system. However, in traditional maintenance policies, maintenance activities have often been assumed to be performed at the same time interval, which may result in higher operational costs and more system failures. Thus, this study presents two non-periodic preventive maintenance (PM) policies for repairable deteriorating systems, employing the failure rate of the system as a conditional variable. In the proposed PM models, the failure rate of the system was restored via the failure rate reduction factors after imperfect PM activities. Operational costs were also considered, which increased along with the operating time of the system and the frequency of PM activities to reflect the deterioration process of the system. A numerical example was provided to illustrate the proposed PM policy. The results showed that PM activities performed at a low failure rate threshold slowed down the degradation of the system and thus extended the system lifetime. Moreover, when the operational cost was considered in the proposed maintenance scheme, the system replacement was more cost-effective than frequent PM activities in the severely degraded system.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.678-685
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• 2005

Estimating parameters of the lifetime distribution is investigated when field failure data are not completely reported. To take into account the reality and the accuracy of the estimates in such a case, the failure reporting probability is incorporated in estimating parameters. Firstly, method of maximum likelihood estimate(MLE) is used to estimate parameters of the lifetime distribution when failure reporting probability is known. Secondly, Expectation and Maximization(EM) algorithm is used to estimate the failure reporting probability and parameters of the lifetime distribution simultaneously when failure reporting probability is unknown. For both case, procedures of estimation are illustrated for single Weibull distribution and mixed Weibull distribution. Simulation results show that MLE obtained by the proposed method is more accurate than the conventional MLE.

• 한국경영과학회지
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• 제36권4호
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• pp.29-41
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• 2011

As industires are evolving into a more advanced type industrial system, service economy has been more emphasized. But with the expansion of the service economy, the failure of the service has also increased. Customers flee caused by the service failure leads to from simple problems like financial loss to serious problems like damaging corporate image. Therefore, if possible, the system providing defect-free service should be established. If this is not possible, preventive measures should be taken in order to minimize the failure. The study as a tool to prevent service failure presents the concepts "service error matrix." And to confirm whether this idea is practical or not, this study investigated the hotel, one of the leading service industries, about actually occurring service failure and applied to service error matrix suggested in this study. Finally service blueprint and Poka-yoke are completed in order to reduce service failure of Y hotel which was the object of the interview for this study.

• 대한안전경영과학회지
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• 제16권3호
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• pp.209-218
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• 2014

An accident related with elevators can cause death or serious injury of operators or passengers. This kind of a fatal accident is due to a failure of elevator. The reduction of failures of elevators is important to reduce the occurrence of elevator accident. Thus, this paper presents the results of analysis for the failure of elevators using the failure data of elevator. The results of analysis can be used to make a maintenance process of elevators.

• 한국건축시공학회지
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• 제4권2호
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• pp.137-142
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• 2004

There was the time of IMF(1998) that management condition of construction business had been the worst. After that time, structural regulation was completed and financial structure was returned to normalcy(2001). At that time, the aim of this paper is that fifteen construction business are researched for process of management condition and capital structure after they is selected as samples for three years, also failure of two-groups is predicted as statistics analysis and multiple discriminant analysis for them. In this paper, It is researched financial statement of business by the forecast experiment of failure and analyzed statistically possibility of failure and success for financial ratio. For them, the fifteen companies of failure and the fifteen companies what were not the failure, for listed company, and the fourteen variables are selected and they are analyzed statistically according to Logit Analysis.

• 대한안전경영과학회지
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• 제3권2호
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• pp.113-121
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• 2001

Today, facilities are composed of many complex components or parts. Because of this characteristics, the frequency of failures is decreasing, but the strength of failures is increasing; therefore, the failure analysis about many complex components or parts was needed. In the former research about Fault Tree Analysis, failure data of similar facilities have been used for forecasting about target system or components, but in case that the system or components for forecasting failure is new or qualitative and quantitative data are given simultaneously, there are many difficulty in using Fault Tree Analysis with this incorrect failure data. Therefore, this paper deal with the Fault Tree Analysis method which be applied with Fuzzy theory in above case. In case that , therefore, if there is no the correct failure data, it is represented a system or components as qualitative variable. subsequently, it converted to the quantitative value using fuzzy theory, and the values used as the value for failure forecast.

• 한국건설관리학회논문집
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• 제4권1호
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• pp.97-105
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• 2003

건설실패에 관련된 정보는 연구문헌, 사례집, 보고서 등에서 제공하고 있지만, 실패정보에 대한 체계적인 분류가 구축되어 있지 않아, 정보의 활용에 많은 문제점이 있다. 따라서 본 논문에서는 국내$\cdot$외의 건설실패연구 관련기관 및 문헌을 조사$\cdot$분석하여 건설실패정보 분류체계를 제안하였는데, 시설물 일반정보, 실패상황정보, 실패원인정보, 실패대책정보의 4개의 대분류로 구성되어 있다. 그리고 각각의 대분류항목은 중분류항목과 소분류항목으로 구성하였다. 본 연구에서 제시한 건설실패분류 체계는 실패사례의 정형화$\cdot$표준화를 통하여 건설산업 참여주체들이 실패정보를 공유함으로써 실패의 재발을 방지하는 유용한 자료로 활용될 수 있을 것이다.

• 대한안전경영과학회지
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• 제13권2호
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• pp.185-193
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• 2011

The successful and sustainable growth of SMEs depends on their ability of strengthen their competitiveness in quality and cost and service more than anything else as a fundamental of operation. Among these key competitive factors of SMEs, quality is the most critical factor in manufacturing business fields. There are many different ways to improve the quality performance but it needs proper management decision to choose the best way what can maximize outputs with minimum inputs. And it needs effective measurement methods and some indicators to analysis the quality performance properly. The quality cost is one of the simplest key indicators to measure the quality performance and the effectiveness of quality related management decisions. In this study, through survey on local SMEs, we found that their average annual quality cost ratio versus turnover - total amount of annual quality cost divided by annual turnover - is around 3.69% excluded some SME's performances what have different quality control measures with others. And we found some results what corresponded with the early studies on the correlations between those categorized quality costs factors and some discrepancies between some of the literature model and the early case study results as follows. There were negative correlations between the Prevention costs and the External failure costs, and the Appraisal costs and the External failure costs, and there was positive correlation between the Appraisal costs and Internal failure costs same as early studies. But, we couldn't found any strong negative correlations between the Cost of control - Prevention costs & Appraisal costs - and the Cost of Failure of control - Internal & External failure costs -.

• 한국융합학회논문지
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• 제11권10호
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• pp.267-277
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• 2020

본 연구는 재창업기업 대표를 대상으로 실패내성이 탐색 활동 및 활용 활동에 미치는 영향과 이러한 활동들이 경영성과에 미치는 영향을 고찰하였다. 최근 재창업을 지원하는 정책적, 사회적 지원이 높아지고 있다. 본 연구는 재창업자의 심리적 요인이 경영성과와 관계가 있는지 검증하고자 한다. 따라서, 심리 및 교육학 변수인 실패내성과 경영학 변수인 경영성과를 융합한 연구모형을 제시하고, 이를 실증 분석하였다. 연구대상은 중소벤처기업진흥공단으로부터 재창업 자금을 지원받은 재창업자를 대상으로 실시하였다. 재창업자의 심리적 특성인 실패내성과 탐색 및 활용 활동에 미치는 영향을 분석한 결과, 모두 긍정적인 영향을 미치는 것으로 나타났고, 탐색 및 활용 활동이 경영성과에 미치는 영향을 분석한 결과, 탐색 활동은 영향을 미치는 않는 것으로 나타났고, 활용 활동은 긍정적인 영향을 미치는 것으로 나타났다. 이 같은 연구 결과를 바탕으로 이론적 시사점과 실무적 시사점을 제공하고자 한다.

• Korean Circulation Journal
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• 제53권7호
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• pp.452-471
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• 2023

The Korean Society of Heart Failure (KSHF) Guidelines provide evidence-based recommendations based on Korean and international data to guide adequate diagnosis and management of heart failure (HF). Since introduction of 2017 edition of the guidelines, management of advanced HF has considerably improved, especially with advances in mechanical circulatory support and devices. The current guidelines addressed these improvements. In addition, we have included recently updated evidence-based recommendations regarding acute HF in these guidelines. In summary, Part IV of the KSHF Guidelines covers the appropriate diagnosis and optimized management of advanced and acute HF.