• 대한전기학회논문지:시스템및제어부문D
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• 제51권1호
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• pp.18-25
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• 2002

The software reliability is defined, and not only the relations between testing time and reliability, but also the relation between duration following failure fixing and reliability are studied in this paper. The release time making the testing cost to be minimum is determined through evaluating the cost for each condition. Also, the release time is determined depending on the conditions of the first reliability, considering the specified reliability. the optimum release time is determined by simultaneously studying two optimum release time issues that determine both the cost related time and the specified reliability related time. And, each condition and limitation are studied. The trend of the optimum time is also examined.

• 대한교통학회지
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• 제17권5호
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• pp.43-55
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• 1999

화물의 시간가치 연구는 운송과정에서 화물이 갖는 중요도를 평가하며 운송중의 재고비용까지 나타내어 효율적인 물류관리를 위한 방향을 제시해 준다. 화물의 시간가치는 화물의 업종에 따라 차이를 보이며, 동일한 업종내에서도 화주의 특성에 따라 차이를 보인다. 이것은 운송시간의 절감에 보이는 화주의 행태가 다르며, 그로 인해 운송시간의 절감에 대한 화주의 지불용이가 각각 다르게 나타나기 때문이다. 본 연구에서는 우리나라 제조업체의 화주를 대상으로 지역간 화문운송의 시간가치를 추정하였다. 연구방법은 화주가 공로운송수단을 선정할 때 중요한 기준이 되는 인식요소를 추출하고, 그에 따라 화주돈을 동질의 업종으로 분할한 후 다항로짓모형을 추정하여 화주집단별 시간가치를 도출하였다. 연구의 결과 지역간 화물운송의 시간가치는 화물업종마다 차이를 보였으며, 평균적으로 한시간의 운송시간을 줄이기 위해서는 출하차량 1대당 1.680원(톤당 389원)을 지불해야 하는 것으로 나타났다. 이를 화물 업종별로 분류하면 의류·직물, 사무기계 ·가전제품, 통신·정밀과학 등은 2,906원으로 추정되었고, 음식료품, 비금속광물, 제1차금속산업, 조립금속산업 및 자동차부품 등은 1,248원으로 나타났다. 그리고 가구, 출판·인쇄물, 화학제품 등은 1,041원의 크기를 보였다. 다음으로 운송중의 재고비용은 평균적으로 화물가격의 9.54%로 추정되었으며, 사무기계·가전제품 등 고가의 화물은 화물가격의 약 50%에 달하는 반면에 비금속광물 등 저가의 화물은 낮은 재고비용을 갖는 것으로 평가되었다.

• 제어로봇시스템학회논문지
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• 제13권6호
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• pp.581-588
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• 2007

In this paper, we propose a delayed feedback guaranteed cost controller design method for linear time-delay systems with norm-bounded parameter uncertainties and nonlinear perturbations. A quadratic cost function is considered as the performance measure for the given system. Based on the Lyapunov method, an LMI optimization problem is formulated to design a controller such that the closed-loop cost function value is not more than a specified upper bound for all admissible system uncertainties and nonlinear perturbations. Numerical example show the effectiveness of the proposed method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.63-70
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• 2000

Light Rail is highlighted for its construction cost and operation ＆ maintenance cost in Korea. However, lack of analysis on driverless operation effect causes many disputes. In this paper, using latest driverless operation cost data. analysed cost reduction effect of it, with comparing present KNR's metropolitan subway signal system. It showed there is enough economic appropriateness B/C 1.241 on interest rate 6%, 1.076 on 8% and 0.943 on 10%, though it couldn't include passenger travel time value.

• 설비공학논문집
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• 제22권10호
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• pp.719-726
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• 2010

In this paper, the appropriate thermal storage time of an air-conditioning system with slab thermal storage was considered by use of summer measurement values. Two standards of heat extraction rate and criterion function were established as the standard that evaluates appropriateness. When heat extraction rate was a standard, zero hour and seven hours were obtained as appropriate thermal storage time, in the case of evaluation by energy consumption and running cost individually. Also, when criterion function was a standard, the difference between energy consumption and running cost was small, it was because the weight function to room air temperature deviation was much bigger than heat extraction rate.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.453-458
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• 2011

The construction industry's importance to nation building, economic empowerment, and contributions to global commerce cannot be over emphasised. However, poor productivity, accidents, rework, time and cost overruns, and client dissatisfaction have characterised the industry performance in a multi-dimensional way. The central issue in this particular research is the seemingly inadequate achievement of optimum performance in the construction process, either with respect to value for money for the client and the entire construction supply chain or value in terms of the utility derived from built assets in spite of efforts by government and governmental bodies such as the Construction Industry Development Board (cidb) to increase industry performance. Therefore, based upon an extensive review of related literature, the paper reports on effects and causes of non-value adding activities in the construction industry in general, and South African construction in particular. The research findings indicate that activities that can be referred to as non-value activities are not only prevalent, but they can also be held responsible for performance related issues in terms of cost, time, quality and health and safety (H&S) in construction; and the exploration of pluralism in the research methodology may result in a robust model based upon the system dynamics approach. Therefore, the study suggests that there is major scope for value optimisation in the construction process especially in terms of availability and implementation of interventions, which have not only proven successful in other industries, but are also adaptable in the construction industry context.

• 대한치과기공학회지
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• 제16권1호
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• pp.78-104
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• 1994

Under the fee for service schedule of Korean health insurance system, rational fee for dental laboratory products based on the cost is required to be formulated. The purpose of this study was to find actual cost of dental laboratory products in case of a University Hospital. Materials of this study were used as follows : 1. Balance sheet at Dec. 31, 1992 and profit and loss report of the year 1992 of the sample hospital 2. Performance report of dental laboratory department. 3. Purchasing and other accounting bills of dental laboratory materials. The following methods were used. 1. Actual cost finding of dental laboratory department was performed. 2. Work sampling methods were used for measuring standard working time by the process of working. 3. To porcelain fused to metal crown(non-precious), Relative value of the cost of dental laboratory products was calculated as 1.00. 4. Fee and cost of those products were compared on the basis of Relative values. The results of the study can be summarized as follow : 1. Overall, it took longs time than other items. to product denture-related items. 2. When several teeth are made in a time, average production time is much sorter than when one tooth is made in a time. 3. The relative price cost of Dicor cast crown and denture related items are higher than the criterion items. 4. The material cost occupies average 11% out of the total price cost, proportion of personnel expenses is average as 60.0%. 5. Some of the components consisting of the price cost are not reflected adequately in setting the level of the reimbursement price. 6. Relative values of dental laboratory products price cost are varied in the range from 0.05 to 2.83, overall, the reimbursement price of dental products appears not to reflect adequately the price cost. On the basis of this study results, the following ideas would be suggested : 1. Fee Schedule of dental laboratory products should be renovated in order to reflect their costs. 2. Dental laboratory product manufacturers should be enlarged for the economy of scale which may be useful for cost- containment. 3. Dental laboratory producters themselves are required to be standardiqed according to the categories of skill.

• 품질경영학회지
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• 제50권2호
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• pp.265-286
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• 2022

Purpose: The time and cost of a project activity exists in a selected mode and there is a quality level for the selected mode, and the time and cost of the current activity is determined by the quality level of the preceding activity. When an activity is a predecessor activity of an activity, it is characterized as a trade-off problem in which the time and cost of the activity are determined according to the quality level of the activity. Methods: A neighbor search heuristic algorithm obtains a solution by (1) randomly determining the mode, quality level, and assignment order for each activity. (2) get a solution by improving the solution by changing the possible modes and quality levels; (3) to find a solution by improving the solution from the point where it is feasible to advance the start time. Here, Case[1] is a method to find the optimal solution value after repeating (1). Case [2] is a method for finding a solution including (1) and (2). Case [3] refers to a method for finding solutions including (1), (2), and (3). Results: It can be seen that the value of the objective function presented by the algorithm changes depending on how the model of the heuristic algorithm is designed and applied. In other words, it suggests the importance of algorithm design and proves the importance of the quality problem of activities in the project schedule. Conclusion: A study significance of the optimization algorithm and the heuristic algorithm was applied to the effect of the quality of the preceding activity on the duration and cost of itself and the succeeding activity, which was not addressed in the project schedule problem.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.138-139
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• 2015

Human productivity of Boring Machine for stack is provided but not its hourly workable quantity(Q-value) in the Equipment ownership cost and expenses section of the Poom-Same that is used for construction cost estimation of public sectors in Korea, which leads to less realistic and subjective estimation for the works. The optimized Q-value of the machine is proposed as a result of thorough investigation into many of its operations.

• 대한산업공학회지
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• 제35권3호
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• pp.194-202
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• 2009

In this paper, we address an optimization problem and a case study for minimizing the cost of inspections incurred throughout an inspection system, which includes a K-stage inspection system, a source inspection shop, and a re-inspection shop. In order to formulate the inspection cost function, we make a time-based flow analysis between nodes (or shops), and derive the limiting sizes of flows between nodes and limiting defective rates by solving a set of nonlinear balance equations. It turns out that the number of items reworked throughout the inspection system is invariant irrespective of the defective rate of items moved through the K-stage inspection system. Hence we define the inspection cost as the total number of items inspected, and we provide an enumeration method for determining an optimal value of K which minimizes the number of items inspected.