• 산업공학
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• 제24권4호
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• pp.274-280
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• 2011

Delayed access to surgery may lead to deterioration in the patient condition, poor clinical outcomes, increase in the probability of emergency admission, or even death. The purpose of this work is to decide the number of patients selected from a waiting list and to schedule them in accordance with the operating room capacity in the next period. We formulate the problem as an infinite horizon Markov Decision Process (MDP), which attempts to strike a balance between the patient waiting times and overtime works. Structural properties of the proposed model are investigated to facilitate the solution procedure. The proposed procedure modifies the conventional value iteration method along with the binary search technique. An example of the optimal policy is provided, and computational results are given to show that the proposed procedure improves computational efficiency.

• 품질경영학회지
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• 제14권2호
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• pp.21-27
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• 1986

This paper deals with a continuous review (s,S) spare part inventory system. The distributions of service life of each part and the replenishment lead time are assumed to be exponential. Assuming that there is never more than a single order outstanding, we obtain the average annual cost of operating the inventory system. If the length of stockout period is small enough to be neglected compared to the length of operating period, the optimal operating policy variables minimizing the cost rate can be calculated iteratively. For the case of one-for-one ordering (that is, s=S-1), an exact cost rate, and a closed form decision rule minimizing the cost rate are obtained for a more general situation in which more than one order is allowed to be outstanding and the distribution of the replenishment lead time is general.

• 한국국방경영분석학회지
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• 제33권1호
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• pp.19-29
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• 2007

본 연구는 최적의 정비주기 산정을 위해 공군의 항공기 정비정보체계(AMMIS, Aircraft Maintenance Management Information System) 및 상태검사의 데이터 분석을 통하여 항공기 부품 신뢰도 분석평가체계를 개발하기 위한 개념설정 및 운영방안에 대한 내용이다. 항공기부품의 고장자료를 선별하여 추출한 후 신뢰도 소프트웨어를 활용해 정비주기를 개선하고 상태검사시 측정한 고장 추세를 통계 소프트웨어로 분석하여 검사 주기를 재설정하는 방법을 통해 항공기 부품 신뢰도 분석평가체계의 운영 모델을 제시한다.

• 직업교육연구
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• 제37권6호
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• pp.1-15
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• 2018

본 연구는 산학일체형 도제학교를 운영하는 두 주체인 학교, 기업 관계자를 대상으로 하여, 이들의 산학일체형 도제학교 정책에 대한 관심도를 분석하여, 향후 이의 효율적인 운영을 위한 시사점을 도출하는 데 그 목적이 있다. 이를 위해 본 연구에서는 어떠한 새로운 변화 도입에 대한 관련자의 관심도를 파악하는 데 활용되고 있는 관심중심수용모형(Concerns-Based Adoption Model; 이하 CBAM)을 활용하였다. 본 연구는 학교와 기업 관계자의 해당 정책에 대한 관심도를 살펴보기 위해서 산학일체형 도제학교의 두 중심 주체(학교, 기업 관계자) 139명(학교 관계자 84명, 기업 관계자 55명)의 응답 결과를 분석에 활용하였다. 분석 결과, 첫째, 현재 산학일체형 도제학교 운영 주체의 해당 정책에 대한 관심도는 비사용자 패턴과 유사하였다. 즉 현재 이들은 해당 정책에 대해 궁금해 하고, 성공적인 운영을 위해서 스스로 수행해야 할 역할이 무엇인지 정도의 수준으로 정책에 대해 관심을 갖고 있었다. 둘째, 산학일체형 도제학교 운영 주체를 학교 관계자와 기업 관계자로 구분하였을 때, 각 주체별 관심도 차이를 살펴본 결과는 다음과 같다. 먼저 0단계(무관심)를 제외하고 학교 관계자의 관심도가 기업 관계자 보다 상대적으로 높게 나타났다. 특히 5단계(협력적 관심)에서 가장 큰 차이가 있는데, 산과 학의 협동이 해당 정책의 성공 요인이므로 두 주체가 협력하여 해당 정책을 운영할 수 있도록 학교 관계자에게는 산학 협동을 할 수 있는 구체적인 방안을, 기업 관계자에게는 산학 협동의 중요성을 인식시킬 필요가 있음을 알 수 있었다. 다음으로 각 운영 주체 모두 4단계(결과적 관심)에서 가장 낮은 강도가 나타났다. 이는 운영 주체의 해당 정책 및 도제학생 평가 측면에 대한 관심이 상대적으로 낮은 것을 뜻한다. 하지만 정책을 개선하고, 보완하기 위해서는 정책에 대한 평가가 필요하며, 도제학생에게 평가는 자격취득과 연관되므로 향후 산학일체형 도제학교 운영 주체에게 평가 관련 다양한 정보를 제공할 필요가 있다.

• 산업공학
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• 제4권2호
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• pp.35-42
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• 1991

Many authors derived MTTF/MTBF for an operating system by analyzing its actual life time data. However, it is difficult to derive MTTF/MTBF when few breakdowns accur throughout a year. In this paper, we address a new approach to solve that problem under a preventive maintenance policy, in which few breakdowns occur, and also introduce a case study using the results obtained.

• 대한안전경영과학회지
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• 제15권4호
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• pp.25-35
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• 2013

Recently, national leisure activities have increased in proportional to having time and money to spare for living on. Especially, camping activities are positioned as a new leisure type for middle class families, so that it is expected that camping facilities are also rapidly increased. However, there is no institutional measures for safe camping activity. It is urgently requested that camping activities including designing and operating campsite are regulated within the legal system. In this study, the status of camping activities and its legal system are investigated. The strategic policy directions for safe camping activity are suggested in the view of legal system, operational guidelines, and institutional supports; (1) the legal basis for camping activities should be prepared. (2) the supervision of campsite management should be improved based on informational services. (3) the self-operation guidelines for campsite owners should be developed and provided. (4) the criteria of safety assessment for design and operating campsite should be prepared. (5) the safety information of campsite should be published and shared among camping communities.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2011년도 추계학술논문집 2부
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• pp.565-568
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• 2011

Google Android framework consists of an operating system and software platform for mobile devices. Using a general-purpose Linux operating system in mobile device has some advantages but also security risks. Security-Enhanced Linux (SELinux) is a kernel-based protection approach which can help to reduce potential damage from successful attacks. However, there are some challenges to integrate SELinux in Android. In this research, we do a study on how to do the integration and find out four challenges. The first one is that the Android file system (yaff2) does not support security namespace for extended attribute (xattr) which is required by SELinux. The second one is that it's difficult to apply SELinux policy to Dalvik process on which an Android application runs on. The third one is that Android lacks methods, tools and libraries to interact with SELinux. The last one is how to update the SELinux policy automatically when installing or removing an application. In this paper, we propose solutions for the above limitations that make the SELinux more adaptive and suitable for Android framework.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1594-1597
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• 2005

A rapid development and a wide use of the Internet have expanded a network environment. Further, the network environment has become more complex due to a simple and convenient network connection and various services of the Internet. However, the Internet has been constantly exposed to the danger of various network attacks such as a virus, a hacking, a system intrusion, a system manager authority acquisition, an intrusion cover-up and the like. As a result, a network security technology such as a virus vaccine, a firewall, an integrated security management, an intrusion detection system, and the like are required in order to handle the security problems of Internet. Accordingly, a router, which is a key component of the Internet, controls a data packet flow in a network and determines an optimal path thereof so as to reach an appropriate destination. An error of the router or an attack against the router can damage an entire network. This paper relates to a method for RSMS (router security management system) for secure networking based on a security policy. Security router provides functions of a packet filtering, an authentication, an access control, an intrusion analysis and an audit trail in a kernel region. Security policy has the definition of security function against a network intrusion.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.257-262
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• 2016

Recently, the subject of reliability attracts a great deal of domestic and international attentions and the extensive research activities are being conducted as well. Such trend exists mainly due to the fact that the research on the subject of reliability not only contributes to the theoretical developments, but also may find a wide range of applications in practice over several fields. In particular, the research regarding the maintenance policy incorporating certain types of warranty for repairable system and its application is being performed extensively by many researchers, and their efforts seem more concentrated on developing new maintenance policies which minimize the expected operating cost incurred for replacement and repair of the system, while keeping the system at high reliability. Effective maintenance policy may reduce the operating cost and decrease the downtime of the system during its mission period and consequently, increase the productivity of the system. In this article, the major areas of interest in the field of reliability and its historic perspectives are given briefly and the theoretical aspects in several fields of reliability including the maintenance and warranty policies is also discussed. Furthermore, the current domestic situation regarding the education and research on reliability is presented, along with the importance of reliability theory and the difficulty of training reliability personnel. Finally, the author's opinion for effective education system is proposed.

• 보건행정학회지
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• 제9권2호
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• pp.1-20
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• 1999

This study was conducted to investigate the predictors of hospital bankruptcy in Korea and to examine the predictive power for 3 types of statistical models of hospital bankruptcy. Data on 17 financial and 4 non-financial indicators of 30 bankrupt and 30 profitable hospitals in 1. 2, and 3 years before bankruptcy were obtained from the hospital performance databank of Korea Institute of Health Services Management. Significant variables were identified through mean comparison of each indicator between bankrupt and profitable hospitals, and the predictive power of statistical models of hospital bankruptcy were compared. The major findings are as follows. 1. Nine out of 21 indicators - fixed ratio, quick ratio, operating profit to total assets, operating profit to gross revenue, normal profit to total assets,normal profit to gross revenue, net profit to gross revenue, inventories turnrounds, and added value per adjusted patient - were found to be significantly predictitive variables in Logit and Probit models. 2. The predicdtive power of discriminant model of hospital bankruptcy in 1. 2, and 3 years before bankruptcy were 85.4, 79.0, and 83.8% respectively. With regard to the predictive power of the Logit model of hospital bankruptcy, they were 82.3, 75.8, and 80.6% respectively, and of the Probit model. 87.1. 80.6, and 88.7% respectively. 3. The predictive power of the Probit model of hospital bankruptcy is better than the other two predictive models.