• 품질경영학회지
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• 제42권4호
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• pp.633-646
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• 2014

Purpose: The conventional predicted MFTBF by military standard has a wide discrepancy to that of real-world operation, which leads to overstock and increase operation cost. This paper introduces a analyzing frame using operational reliability and cost data to overcome the discrepancy, and provides reliability improvement process employing the analyzing frame. Methods: This paper suggests Reliability-Cost Matrix (R-C Matrix) and Operational Reliability & Cost Index (ORCI) as a tool for reliability evaluation. Results: KOREIP(KAI's Operational Reliability Evaluation and Improvement Process) is developed employing Reliability-Cost Matrix and Operational Reliability & Cost Index. Conclusion: KOREIP provides a process and its activities based on Reliability-Cost Matrix frame. The process and activities leads reliability improvement of aerospace electronic equipments by means of categorizing and follow-up action based on the concept of frame.

• 전기학회논문지
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• 제63권2호
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• pp.205-210
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• 2014

The micro grid considered in this paper consists of a diesel generator, a photovoltaic array, a wind turbine, a fuel cell, and a energy storage system. This paper explains and simulates the micro grid components in terms of accuracy and efficiency of having a system model based on the costs of fuel as well as operation and maintenance. For operational efficiency, the objective function in a diesel generator consists of the fuel cost function similar to the cost functions used for the conventional fossil-fuel generating plants. The wind turbine generator is modeled by the characteristics of variable output. The optimization is aimed at minimizing the cost function of the system while constraining it to meet the customer demand and safety of micro grid. The operating cost in fuel-cell system includes the fuel costs and the efficiency for fuel to generate electric power. To develop the overall system model gives a possibility to minimize of the total cost of micro grid. The application of optimal operation can save the interruption costs as well as the operating costs, and improve reliability index in micro grid.

• 전기학회논문지
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• 제60권7호
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• pp.1293-1298
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• 2011

This paper presents an Unified Index which can evaluate a performance of a distribution system based on value-based methodology. Reliability cost and voltage sags cost are calculated for each load point using Reliability Sector Customer Damage Function(SCDF). Aging cost is calculated for each load point using Aging SCDF. Power loss cost and operation cost are calculated for the system. By summation of each cost of load point and system, power quality cost can be obtained. Finally, this paper developed an unified index which can show the performance of a distribution system. Presented method has been applied to a real system, the usefulness of the method has been verified.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.9-15
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• 2005

In the operation of distribution systems, DGs (Distributed Generations) are installed as an alternative to extension and the establishment of substations, transmission and distribution lines according to the increasing power demand. In the operation planning of DGs, determining optimal capacity and allocation achieves economical profitability and improves the reliability of power distribution systems. This paper proposes a determining method for the optimal number, size and allocation of DGs in order to minimize the operation costs of distribution systems. Capacity and allocation of DGs for economical operation planning duration are determined to minimize total cost composed with power buying cost, operation cost of DGs, loss cost and outage cost using the GA (Genetic Algorithm).

• 전기학회논문지
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• 제59권10호
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• pp.1703-1711
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• 2010

Electric power utilities are facing increasing uncertainties regarding the economic, political, societal, environmental constraints under they operate and plan their future systems. The utilities have to integrate consumers' interruption cost representing reliability worth of electricity into the process of determining the optimum investment level. In order to do so, the estimated outage cost must be included into quantitative index corresponding to system capital and operation investment cost to establish an optimal expansion plan. This paper is a study on the outage cost assessment by using macro approach for calculating IEAR(Interrupted Energy Assessment Rates) and the TRELSS(Transmission Reliability Evaluation for Large-Scale Systems) program was used to calculate EENS(Expected Energy Not Served).

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.387-390
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• 2008

The importance of the life cycle cost analysis for construction projects of bridge has been recognized over the last decades. Accordingly, theoretical models, guidelines, and supporting softwares have been developed for the life cycle cost analysis of bridges. However, it is difficult to predict life cycle cost considering uncertainties precisely. This paper presents methodology for optimal design of substructure for a steel box bridge. Total life cycle cost for the service life is calculated as sum of initial cost, damage cost considering uncertainty, maintenance cost, repair and rehabilitation cost. The optimization method is applied to design of a bridge substructure with minimal cost, in which the objective function is set to life cycle cost and constraints are formulated on the basis of Korean Bridge Design Specification. Initial cost is calculated based on standard costs of the Korea Construction Price Index and damage cost on the damage probabilities to consider the uncertainty of load and resistance. An advanced first-order second moment method is used as a practical tool for reliability analysis using damage probability. Maintenance cost and cycle is determined by a stochastic method and user cost includes traffic operation costs and time delay costs.

• 한국건설관리학회논문집
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• 제6권4호
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• pp.164-171
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• 2005

최근 생애주기비용 분석의 중요성이 대두됨에 따라 공동주택 리모델링 사업에서의 생애주기비용 분석을 위한 이론적 모델, 표준지침 및 소프트웨어 등이 개발되어지고 있다. 그러나 현재까지도 실질적인 안전진단에 대한 과거 보수이력데이터의 부재로 인한 LCC분석 결과에 대한 신뢰수준이 여전히 미흡하다. 본 연구에서는 사례 공동주택의 신뢰성에 기초한 LCC분석을 통해 리모델링 전략을 평가하고, 장래 요구되는 리모델링 조치수준의 비교 $\cdot$ 분석을 통해 적정 경제성지수를 제시함과 동시에 최근 연구가 활발히 진행 중인 공동주택 리모델링에 대한 실적 LCC 기초자료를 얻고자 하였다. 본 연구에서 제안된 퍼지로직에 기초한 안전성평가와 LCC분석모델은 공동주택 리모델링사업에서의 가치 지향적 설계대안 선정, 경제성평가 및 합리적인 예산의 분배 등에 크게 기여할 것으로 기대된다.

• 한국가스학회지
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• 제24권4호
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• pp.84-92
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• 2020

대부분의 화학공장 내 설비는 유해물질을 취급하거나, 일상적으로 접할 수 있는 온도 및 압력의 범위를 벗어난 환경에서 가동되며 이러한 응력 및 환경조건으로 인하여 노후화에 취약하다. 이러한 조건에 노출된 설비는 지속적인 손상이 누적되어 고장이 발생할 가능성이 높아짐은 물론, 정비 및 교체를 하지 않는다면 사고로 이어진다. 전세계적으로 위험성기반검사(Risk Based Inspection)라는 권고지침이 통용되고 있다. 하지만 RBI는 이미 일정시간 경과한 설비에 대해서는 한계가 존재한다. 적절한 점검을 수행하는 우리나라 울산 산업단지의 노후화 실태 조사 결과, 많은 수의 설비들이 사용기간이 20년을 경과하였다. 또한, 사고가 일어난 설비 대부분이 20년 이상 운영해 왔다. 따라서 본 연구에서는 일정 사용기간이 초과된 장치를 노후설비로 분류하는 기준을 제시하였다. 또한, 이에 대하여 정량적 위험성평가를 진행하였다. 이로 인해 도출된 해당 노후설비의 위험성을 Economic index로 표현하여 손실비용을 산정하고 Risk를 감소하기 위하여 비용편익 분석 방법을 활용한 안전투자 방법을 제안하였다. 본 연구에서 제시한 정량적 위험성 평가를 이용한 노후설비의 비용편익 분석 방법을 활용하여 노후 설비의 성능 향상 및 수명 연장, 생산 효율성 및 설비 계통 신뢰도 향상, 안전관리 비용 인식 변화, 그리고 직원의 안정감 증대, 손실비용의 감소를 기대할 수 있다.

• 간호행정학회지
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• 제7권2호
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• pp.265-284
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• 2001

The case management has been applied to improve the quality of care and the cost-effectiveness in the most health care institutions. In a way of case management, the critical pathway(CP) has been executed in many acute care settings, focused on the diagnoses with high cost, high volume, and high risk. This study was conducted to develop a case management program using CP as an intervention of patients with lumbar spinal stenosis for the surgery of posterolateral fusion, and to find out the effects of the critical pathway on the quality of nursing care, patient satisfaction as an outcome of care, length of stay and medical charge, and nurses' job satisfaction. At the same time, patients' functional states were checked with the Oswestry Low Back Pain Index, to show that the CP would not decrease the patients' function compared to the control group. The subjects were 25 control patients with a usual operation of lumbar fusion and 25 experimental patients with CP. They were all female, aged $50s{\sim}70s$, admitted in the Orthopedic surgery ward of a university hospital. Also nurses on the floor using CP were asked to respond to measurement tool of job satisfaction before and after the application of CP, and compared with other nurses on the different wards. Data were analyzed with t-test for continuous variables and chi-square for non-parametric variables in addition to the reliability test of the measurement tools. The results of this study were as followings: 1. Patients' functional states The differences in Oswestry scores of the experimental and control groups assessed at preoperation and at discharge were not statistically significant. The change in scores of the experimental group measured at preoperation and at discharge was larger than that of the control group, however the difference was not statistically significant. The results indicate that the CP did not decrease the patients' functional status. 2. The quality of nursing care The total of quality of nursing care given to the experimental group was better than that of the control group(P=.000). In addition, the experimental group showed better scores of quality of every item of care than the control group(P=.000 -.004). 3. Patient satisfaction Patients of the experimental group were not more satisfied with general care than the control group. But they were more satisfied with discharge care of 'explanation about medication, body posture, and brace application' and 'explanation about the adjustment of daily living and exercise during recovery'(P= .047, P=.028). 4. Nurses' job satisfaction Nurses working with the CP showed more job satisfaction than before the CP introduction(P=.048). But the control group of nurses on a different floor showed no change in job satisfaction at the same period of time. 5. Length of stay and medical charge The mean length of stay of the experimental group was shorter than that of the control group without statistical significance. The charge of medication and treatment of the experimental group were smaller than that of the control group(P=.011, P=.000). The results of the study support that the case management using critical pathway enables to improve the quality of care and job satisfaction, to reduce the medical charge, and consequently to increase satisfaction with care. However, the case management should be instituted focusing on the quality improvement of nursing and the client satisfaction, not just for the purpose of cost-effectiveness of health care facilities.