• International Journal of Computer Science & Network Security
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• 제22권2호
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• pp.357-361
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• 2022

Employing the available technologies and utilizing the advanced means to improve the level of health care provided to citizens in their various locations. Citizens have the right to get a proper health care services despite the location of their residency or the distance from the health care delivery centers, a goal that can be achieved by utilizing air ambulance systems. In such systems, aircrafts and their life spans are the essential component, the flight duration of the aircraft during its life span is determined by the maintenance schedule. This research, enhances the air ambulance systems by presenting a proposal that maximizes the aircraft flight duration during its life span. The enhancement will be reached by developing a set of algorithms that handles the aircraft maintenance problem. The objective of these algorithms is to minimize the maximum completion time of all maintenance tasks, thus increasing the aircraft operation time. Practical experiments performed to these algorithms showed the ability of these algorithms to achieve the desired goal. The developed algorithms will manage the maintenance scheduling problem to maximize the uptime of the air ambulance which can be achieved by maximizing the minimum life of spare parts. The developed algorithms showed good performance measures during experimental tests. The 3LSL algorithm showed a higher performance compared to other algorithms during all performed experiments.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.784-791
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• 2007

Most operational organization and railway authority which conduct scheduled maintenance(SM) have carried out the preventive maintenance(PM) based on the information provided from supplier and manufacturer of railway system. However these activities are far away from reality and low the efficiency, it is because an appropriate methods for system selection didn't take into account for improving maintenance efficiency. Therefore, the current SM tasks and maintenance activities lead to lots of spend on the cost and time. To solve the above problem, this thesis presents new approach methodology. This proposes the criteria for reliability centered maintenance(RCM) system selection through level of quantification of each parameter, i.e, frequency, severity and maintenance cost, etc. To do this, the field operation data and information of maintenance cost are essential. As applying this methodology, we can look forward to improving efficiency of PM/SM, and reducing cost.

• 대한산업공학회지
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• 제42권3호
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• pp.241-248
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• 2016

Plant life cycle consists of design, construction, certification, operation, and maintenance phases, and various and enormous plant life cycle data is involved in each phase. Plant life cycle data should be linked with each other based on its proper relationships, so that plant operators can access necessary plant data during their regular operations and maintenance works. Currently, the relationships of plant life cycle data may not be defined explicitly, or they are scattered over several plant information systems. This paper proposes high level design of a plant life cycle data management system based on pre-defined plant life cycle database design. ISO-15926 standard is adapted for the database design. User-interface designs of the plant life cycle data management system are explained based on analysis of plant owners' requirements. A conceptual design of the database is also described with the entity-relationship diagram.

• Journal of Chest Surgery
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• 제26권4호
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• pp.249-254
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• 1993

Atrial fibrillation is commonly associated with organic mitral valve disease including rheumatic valvular heart diasease or mitral valve prolapse and so forth. Although spontaneous sinus reversion may occur in some patients after mitral valve operation, recurrence of atrial fibrillation is the rule in most of these patients. We have tried to maintain sinus rhythm after mital valve operation with oral quinidine therapy, and we will show the efficacy of this therapy in this report. From January 1986 to August 1992, 60 patients of mitral valvular heart disease, who had had atrial fibrillation preoperatively and gained sinus rhythm postoperatively, were selected for this study. These patients were divided into 2 groups: Control group [n=30] and Quinidine trial group [n=30]. The age,sex, duration of symptoms,left atrial size and other risk factors of the reversion to atrial fibrillation were adjusted to be similar between the two groups. The maintenance rate of sinus rhythm was calculated by Kaplan-Meier method, and the rate was significantly higher in quinidine trial group than in control group [ p=0.0001 ]. Univariate analysis was performed on the risk factors of reversion to atrial fibrillation, and the difference of maintenance rate between the two groups were corrected with this result: the difference was still statistically significant [ p=0.0205 ]. The quinidine levels were measured in postoperative days, and there were no difference of serum quinidine level between the quinidine success group and quinidine failure group. In conslusion, oral quinidine therapy was effective for the maintenance of sinus rhythm after mitral valve operation compared to control group, and there was no correlation between the serum quinidine level and clinical efficacy of quinidine therpy.

• 대한공업교육학회지
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• 제45권2호
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• pp.1-20
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• 2020

이 연구의 목적은 화학공업을 공부하는 학생들이 액위제어를 쉽게 이해할 수 있도록 하기 위해, 조립형 액위제어 실험장치를 제작하고 이를 수업에 적용할 수 있는 체험활동과제를 개발하는 것이다. 이를 위해 2015 개정 교육과정 화학공업 실무과목에서 액위제어와 관련된 내용요소를 분석하여, 조립형 액위제어 실험장치를 활용하는 체험 활동과제를 개발하여 전문가 검증을 마친 후, 16차시의 체험활동과제를 S 마이스터고등학교 학생 19명에게 적용하였다. 이 연구에서 얻은 결과는 다음과 같다. 첫째, 기존 완성형 액위제어 실험장치를 분석하고, 이를 토대로 학생 수준에서 조립 가능하며 실습에 활용할 수 있는 새로운 조립형 액위제어 실험장치를 설계·제작하였다. 둘째. 2015 개정 교육과정의 NCS기반 '화학공정유지운영' 실무과목의 내용을 분석하여 액위제어와 관련된 학습 내용들을 추출하였다. 이 액위제어 관련 내용 중에서 공정 흐름도의 이해, 액위제어 실험장치 제작, 유량 측정, 액위제어 현상 확인 등의 실습을 위 조립형 액위제어 실험장치로 진행하여 액위제어 관련 내용을 체계적으로 학습할 수 있도록 하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1174-1179
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• 2004

In general, the national rail system put an emphasis on distribution planing of stations for smooth operation of transporting goods, train allocation, parking, and maintenance. Since the national rail system is operated on the ground level, it is feasible to improve various aspects of the system during its operation. On the contrary, urban rail system is operated in the limited space under the ground, and thus, improving various aspects of the system during its operation is infeasible. Specifically, the urban subway system must have a comprehensive track distribution plan because the urban subway system has to operate in a limited environment such as it operates in a much shorter time period, The subway system has to be ready for various operations and events such as trains returning in the opposite direction. parking trains that need repair, parking during night time, storing various maintenance equipments, and connections to other tracks. Furthermore, considering the future extension of tracks, a comprehensive track distribution plan is a must.

• 해양환경안전학회지
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• 제27권1호
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• pp.53-59
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• 2021

해양 운송 산업은 특성상 항공 및 철도 등의 다른 운송 산업보다 비교적 늦게 신기술이 적용되는 산업이다. 현재 대부분의 선박은 기계장치 및 시스템에 문제가 발생하거나 운용 시간 기반으로 정비를 하는 사후 정비(Corrective Maintenance, CM)와 예방 정비(Preventive Maintenance, PM)에 속하는 시간 기반 정비(TBM, Time Based Maintenance)가 적용되고 있다. 그러나 높은 유지보수 비용이 요구되고, 육상의 즉각적인 지원이 어려우며, 선박이 멈추면 즉시 위험에 노출되는 해양 환경에서 운영되는 선박에서 과도한 단순 정비로 인한 인력과 비용 낭비, 예측되지 못한 고장 및 결함으로 유발되는 사고 등으로 인해 운용 효율화 측면에서 기존 정비법에 대한 한계점이 문제시 되고 있다. 예지 정비(Predictive Maintenance, PdM)는 진보된 기술로 기계의 상태 및 성능을 모니터링하여 고장시기를 예측하여 정비하는 방법으로 핵심 기계장치가 항상 최상의 작동 상태를 효율적으로 유지할 수 있도록 한다. 본 논문은 해양 환경에서 PdM의 적용성에 중점을 둔 해양 예지 정비(MPdM, Maritime Predictive Maintenance)에 대해 고안하였으며, 제시된 MPdM은 지리적 고립과 극한 해양 상황 등 해양 운송 산업의 특수한 환경을 고려하여 설계되었다. 본 논문은 선진 미래 해양 운송을 가능하게 하는 MPdM이라는 개념과 그 필요성을 제안한다.

• 대한산업공학회지
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• 제30권4호
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• pp.261-266
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• 2004

In this paper, the software reliability growth model which incorporates the periodic maintenance after the release is proposed. Using the proposed model, the debugging and periodic maintenance cost subject to the required level of the software reliability are investigated. An optimal software release time is derived for a fixed interval of periodic maintenance. To validate the proposed model, release times obtained in this study are compared with examples. The proposed investigation is expected to be served as one of factors in determining the release time of the software where periodic maintenance is considered.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.362-368
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• 2008

The purpose of this is providing employees who take charge of operation and maintenance at power plant with education contents that can be used for self-studying and on the job training through their computers. We developed the education contents for making actually application possible using this piping and instrument diagram(P&ID), operation and maintenance procedure, unit specification and material of 500MW thermal power plant those include unit equipment 3-dimension animation, character and narration performance considering making teaching plan, flexibility, extension, reuse, maintenance and focusing on user. Specially, we developed the flash type education contents about power plant operation based on the plant 3-dimension animation and the spot real picture concerned about new generation trend for power plant incoming employees actual knowledge. in addition, this contents apparently contributed to improve the level of employees technical power as distributed to employees.

• 벤처창업연구
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• 제9권2호
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• pp.81-86
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• 2014

본 논문에서는 그룹교체 정책과 예비품 재고정책을 동시에 고려하여 최적화하는 방안을 제시한다. 일반적으로 보전정책들은 예비품의 재고가 늘 가용하다고 가정하고 있으나 예비품의 재고 확보 여부에 의해 보전활동은 영향을 받을 수밖에 없다. 동일한 여러 유닛들이 동시에 운용될 때 이용되는 그룹교체정책을 바탕으로 이를 지원하기 위한 최적 재고수준을 결정한다. 일정한 개수의 유닛이 고장 나는 시점에서 그룹교체를 수행한다. 예비품의 재고는 일정 횟수의 그룹교체를 할 만큼 주문하여 유지한다. 보전비용과 재고비용 등 운용비용을 최소화할 수 있는 최적의 그룹교체 주기와 재고수준을 구한다.