• Journal of the military operations research society of Korea
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• v.6 no.1
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• pp.79-92
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• 1980

In cost-only incentive contract the emphasis is the attainment of efficient and effective cost control. In contrast multiple incentives contract correlates contractor's profit motives with the generalized government objective function, the decision variables of which are performance or quality (technical progress), time or schedule (timely development and delivery) and the cost (efficient and effective cost control) Under multiple incentive structure, it is essential to formulate the trade-off curves between cost and performance, which are called iso-fee curves. Trade-off curves depict the combination of cost and performance achievement for which the contractor will be rewarded with the same fee. The basic function of trade-off curves is to show he the contractor will be motivated by incentive arragement to trade off or sacrifice the achievement in one incentive element for the acnievment in another.

• Journal of Construction Engineering and Project Management
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• v.4 no.3
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• pp.53-59
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• 2014

Project managers are responsible to conduct project on time with least amount of costs and the most possible quality with respect to shortage of resources and environmental certainties. They have to make the best decision to reach such conflicting objects. In this study the project scheduling with multi goals-multi modes was planned in fuzzy conditions under resource constraints and expanded by fuzzy goal programing (FGP). The project cost was calculated by the price of renewable resources and the quality criteria were evaluated by the quality function deployment method (QFD). Finally the model was verified by a construction case study with 22 activities along with solving by GAMS. The results showed that this model could provide a systematic framework to facilitate the decision making process and made the project managers to be able to schedule the project closer to reality.

• Journal of Korean Society for Quality Management
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• v.31 no.4
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• pp.176-183
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• 2003

The concept of cost of quality has become important economic measures of quality issues for several decades. Most of the research to date has focused on the problem and solution under static business conditions. However, some researchers have found that prevention cost of COQ is one of the expenses of investment and the payback will be shown by the improvement of product quality. These approaches have considered cost of quality issues based on a time factor. It means that there is a trade­off between prevention/appraisal costs and failure costs. Based on a capital budgeting approach, this research reviews the economics of quality improvement activities and proposes the decision criteria to justify quality improvement activities.

• Journal of Korean Society for Quality Management
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• v.50 no.2
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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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1497-1504
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• 2009

This Paper Propose a method to reduce the calculation time in JPEG2000. That is, if a coefficient is estimate a upper-level subband and its descendents skip the scan process. There is a trade-off relationship between the calculation time and the image quality or the amount of output data, the calculation time and the amount of output data decreases, but the image degradation increases. The experimental results showed that in calculation time was 35% in average, which means that ls ge ses. The ein calculation time and output data can be obtls ed with a cost of an acceptlble image quality degradation.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.550-564
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• 2020

Distillation columns are one of the main equipment used for the separation of chemical components in petrochemical process design. However, in spite of the efficient operation in wide range, and the advantage of data collection for equipment verification, the distillation columns are inherently known for high energy consumption and capital cost. Hence, the trade-off analysis needs to be done between investment cost and operation cost to develop the most economical distillation columns. This study was conducted using Aspen Plus, a popular process simulation program, in the pursuit of broad application by as many process engineers as possible. In this paper, design variables for optimization of distillation columns were defined to improve emphatically the design quality with reducing erratic practice of many engineers. In addition, by eliminating unnecessary reviewing step and establishing systematic and efficient procedures, the amount of time for design and human resources were minimized. Aspen Process Economic Analyzers (APEA) program was introduced in order to calculate the investment cost reliably, and the efficient systematic procedure for utilization of APEA was established.

• Journal of Computational Design and Engineering
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• v.1 no.4
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• pp.256-265
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• 2014

Energy efficiency is an essential consideration in sustainable manufacturing. This study presents the car fender-based injection molding process optimization that aims to resolve the trade-off between energy consumption and product quality at the same time in which process parameters are optimized variables. The process is specially optimized by applying response surface methodology and using non-dominated sorting genetic algorithm II (NSGA II) in order to resolve multi-object optimization problems. To reduce computational cost and time in the problem-solving procedure, the combination of CAE-integration tools is employed. Based on the Pareto diagram, an appropriate solution is derived out to obtain optimal parameters. The optimization results show that the proposed approach can help effectively engineers in identifying optimal process parameters and achieving competitive advantages of energy consumption and product quality. In addition, the engineering analysis that can be employed to conduct holistic optimization of the injection molding process in order to increase energy efficiency and product quality was also mentioned in this paper.

• Journal of Computing Science and Engineering
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• v.10 no.2
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• pp.68-73
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• 2016

An efficient texture compression method is proposed based on a block matching process between the current block and the previously encoded blocks. Texture mapping is widely used to improve the quality of rendering results in real-time applications. For fast texture mapping, it is important to find an optimal trade-off between compression efficiency and computational complexity. Low-complexity methods (e.g., ETC1 and DXT1) have often been adopted in real-time rendering applications because conventional compression methods (e.g., JPEG) achieve a high compression ratio at the cost of high complexity. We propose a block matching-based compression method that can achieve a higher compression ratio than ETC1 and DXT1 while maintaining computational complexity lower than that of JPEG. Through a comparison between the proposed method and existing compression methods, we confirm our expectations on the performance of the proposed method.

• Health Policy and Management
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• v.17 no.4
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• pp.113-133
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• 2007

The present study was conducted to measure health-related utility for post-menopausal symptoms among Korean woman. A survey questionnaire was developed to measure utility based on visual analogue scale(VAS) and time trade-off method (TTO). From January 29 to February 3, 2007, a face-to-face interview was conducted with 274 women aged 45 to 60 to ask about their subjective utility for hypothetical health status of mild or severe post-menopausal symptoms. Among the participants, 160 were recruited from outpatient departments of 3 hospitals and 114 from 2 sports centers located in Seoul. For mild symptom, the average utility score of the respondents was $0.63{\pm}0.14$ based on VAS and $0.61{\pm}0.26$ based on ITO. For severe symptoms, the average utility was $0.39{\pm}0.16$(VAS) and $0.44{\pm}0.27$ (TTO). For severe symptom, a higher utility score was observed for TTO than for VAS, which is consistent with earlier studies and thus supports the validity of the utility measurement in this study. Overall, the severity of post-menopausal symptoms of the respondents themselves was not significantly associated with the utility score that the respondents answered for hypothetical health status. Multiple regression analysis results showed that the utility score was significantly higher among respondents with older age, higher education, higher family income, and from hospitals. It is expected that the utility score measured in this study will enhance the understanding of the quality of life of women after menopause and will be used to conduct cost-utility analysis of health care interventions to treat post-menopausal symptoms.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.493-501
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• 2014

Coverage completeness is an important indicator for quality of service in wireless sensor networks (WSN). Due to limited energy and diverse working conditions, the sensor nodes have different lifetimes which often cause network holes. Most of the existing methods expose large limitation and one-sidedness because they generally consider only one aspect, either coverage rate or energy issue. This paper presents a novel method for coverage hole detection with residual energy in randomly deployed wireless sensor networks. By calculating the life expectancy of working nodes through residual energy, we make a trade-off between network repair cost and energy waste. The working nodes with short lifetime are screened out according to a proper ratio. After that, the locations of coverage holes can be determined by calculating the joint coverage probability and the evaluation criteria. Simulation result shows that compared to those traditional algorithms without consideration of energy problem, our method can effectively maintain the coverage quality of repaired WSN while enhancing the life span of WSN at the same time.