• Management Science and Financial Engineering
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• v.11 no.1
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• pp.63-78
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• 2005

Disassembly scheduling is the problem of determining the ordering and disassembly schedules of used or end-of-life products while satisfying the demand of their parts or components over a certain planning horizon. This paper considers the case of the assembly product structure for the cost-based objective of minimizing the sum of purchase, setup, inventory holding, and disassembly operation costs. To represent and solve the problem optimally, this paper presents an integer programming model, which is a reversed form of the multi-level lot sizing formulation. Computational experiments on an example derived from the literature and a number of randomly generated test problems are done and the results are reported.

• Journal of Welding and Joining
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• v.11 no.1
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• pp.21-32
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• 1993

A cracking failure of a austenitic stainless steel elbow in a naphtha cracking line in a petrochenmical plant occurred, resulting in leakage of organic compound flowing inside the elbow. Due to the failure, emergency shutdown of the plant was enforced to repair the troubled part of the line. The repair cost as well as production loss during the unscheduled plant shutdown has cost the company a great amount of financial loss. In this studies, a failure analysis of the cracked elbow was performed using NDT, chemical analysis, microstructural analysis including optical microscopy as well as scanning electron microscopy with EPMA, mechanical testings such as tensile testing, hardness testing and Charphy impact test fractography. The results indicated that several problems such as a welding defect and presence of a detrimental phase which was found to be relate to improper postforming heat treatment process was identified and the failure was concluded to be due to a low temperature embrittlement of the defect-containing elbows.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.121-121
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• 2018

Copper is a promising electronic material due to low cost and high electrical conductivity. However, the oxidation problem in an ambient condition makes a crucial issue in practical applications. In here, we developed a simple and cost-effective Cu patterning method on a flexible PET film by combining a solution processable Cu nanoparticle patterning and a low temperature post-processing using acetic acid treatment, laser sintering process and acid-assisted laser sintering process. Acid-assisted laser sintering processed Cu electrode showed superior characteristics in electrical, mechanical and chemical stability over other post-processing methods. Finally, the Cu electrode was applied to the flexible electronics applications such as flexible and transparent heaters and touch screen panels.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.72-73
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• 2018

The accuracy of contingency estimation plays an important role for dealing with the uncertainty of the financial success of construction project. Its' estimation may be used for various purposes such as schedule control, emergency resolve, and quality expense, etc. This paper presents a contingency estimation method which is schedule control specific. The method 1) implements stochastic EVMS, 2) detects a specific timing for schedule compression, 3) identifies an optimal strategy for shortening planned schedule, 4) finds a probability density function (PDF) of project cost overrun, and 5) estimates the optimal contingency cost based on the level of confidence. The method facilitates expeditious decisions involved in project budgeting. The validity of the method is confirmed by performing test case.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.165-166
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• 2018

The main focus of this study is the analysis of the importance of the planning work of apartment housing projects. Group the detailed work of the facility into five major tasks, categorize each into five major categories, organize the construction plans (P1 through P 6), name the plans (C4), and analyze the quality of the environmental management plans (E1 through E 4) Finally, this study derived major planning tasks from the correlation between planning and cost metrics and from the T-test.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.206-209
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• 2001

This paper illustrates a new method for reliability evaluation at load points in a composite power system. The algorithm includes uncertainties of generators and transmission lines as well as main transformers at substations. The CMELDC based on the new effective load model at HLII has been developed also. The CMELDC can be obtain from convolution integral processing of the outage capacity probabilistic distribution function of the fictitious generator and the original load duration curve given at the load point. The CMELDC based on the new model at HLII will extend the application areas of nodal probabilistic production cost simulation, outage cost assessment and reliability evaluation etc. at load points. The characteristics and effectiveness of this new model are illustrated by a case study of a small test system.

• Journal of ILASS-Korea
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• v.22 no.4
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• pp.203-209
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• 2017

The International maritime organization(IMO), in an effort to slow down the global warming, proposes reduction in ship's speed as a way to lower the rate emissions from ships. In addition, since ship's fuel cost have been increased, the shipping volumes, fuel-saving technology are being required urgently. Therefore, in this present study, a method of reducing the fuel cost that can improve the performance of the diesel engine was tried by introducing a predetermined amount (0.1~0.3% of the mass amount of fuel used) of hydrogen fuel additive. The experimental conditions of the test engine were 1500rpm and torque BMEP-10b ar. The engine performances (power output, fuel consumption rate, p-max, exhaust temperature) were compared before and after addition of hydrogen fuel additives. This experimental study confirmed reducing at least 2% fuel consumption and 2.19% NOx emission.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.854-862
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• 2002

In the previous research, a simplified correlation method was developed as an easy prediction tool for comparing energy use of cooling plants. The purpose of this paper is to test the applicability of this method for economic evaluation with two zones of a 20-story commercial building in Seoul. The results of this method were compared with the DOE-2 simulation and actual measured data. Then, Comparisons of life cycle cost were carried out for three types of cooling plants. Testing of one zone showed good agreement of within 10% error in cooling energy use and within 2% error in LCC. But testing of the other zone indicated that the use of this method were invalid when input variables were used beyond its valid range.

• International Journal of Railway
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• v.5 no.4
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• pp.144-147
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• 2012

New transport technologies have been rapidly developed and various transport systems are ready to introduce. However, there no exists effective decision making tools for pre-feasibility studies on transport systems. The pre-feasibility studies should provide reliable solutions about whether a certain transport system is feasible or not by cost-benefit analysis and effectiveness test of enhancing regional economy. This study introduces the smart transport investment/information system (SMARTIS) for supporting decision making with ease, fast and reliable methods. The SMARTIS incorporates travel demand estimates into the process of feasibility studies with automatic data processing methods to give reliable solutions quickly. The SMARTIS is expected to be informative for transit agencies, planners, and operators.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.217-221
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• 2001

Barber bogie and Y25 bogie is the main bogie of freight car which is used in the Korean railway. In case of Barber bogie and a mixed formation tile maximum speed limit of empty car is 70 km/h and that of loaded car is 90 km/t and also it runs a speed of 110 km/h in time of an exclusive formation of Y25 bogie. The car named as high speed freight car at present is Y25 bogie which modeled on the Y25 bogie or Europe developed in 1993, Y25 bogie has no problem about the running capacity up to the speed of 110 km/h, but it works as limiting factors to tile increasing cost of maintenance and repair expenses which caused by repair of bogie and the cost of materials. This study is going to describe the contents examined by analysis and tests, aimed at being used as an index of plan in the future through the strength test of high speed freight car which is used now.