• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.245-251
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• 2004

Determination the optimal containership size is the most important factor for competitiveness if shipping companies. Accordingly, the objective if this research is determining the optimal containership size by service routes. Total shipping cost is calculated at the ground if capital cost, vessel operation costs, voyage costs, port charge and miscellaneous cost for 'Europe-Far East', 'Far East-North America' and 'Europe-Far East-North America' Services. Finally, the optimal containership size was utilized through total shipping cost, slot quantity if containership and average throughput by containership.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1511-1519
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• 2013

This paper proposes the allocation method for capacitor-reactor banks in a distribution system with dispersed generators to reduce the installation costs, the maintenance costs and minimize the loss of electrical energy. The expected lifetime and maintenance period of devices with moving parts depends on the total number of operations, which affects the replacement and maintenance period for aging equipment under a limited budget. In this paper, the expected device lifetimes and the maintenance period are included in the formulation, and the optimal operation status of the devices is determined using a genetic algorithm. The optimal numbers and locations for capacitor-reactor banks are determined based on the optimal operation status. Simulation results in a 69-bus distribution system with the dispersed generator show that the proposed technique performs better than conventional methods.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2409-2414
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• 2002

The surfaces of prototypes become rough due to the stair-stepping which is the inevitable phenomenon in the Rapid Prototypes are not used only for the verification of feature. The grinding, coating, or the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. The solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. the solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the regions for post-processing. the factors to cause the surface roughness and their effects are analyzed through the experiments. Software modules are developed to predict the surface roughness of each face in the prototyping with the result. An experimental compensation method is developed to apply the modules to various RP equipments, materials and build styles. The build direction is searched with use of genetic algorithm to maximize the total areas of the surface of which roughness is better than the user-defined value.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1369-1375
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• 2017

This paper presents an optimal operation scheduling algorithm for a smart home with energy storage system, electric vehicle and distributed generation. The proposed algorithm provides the optimal charge and discharge schedule of the EV and the ESS. In minimizing the electricity costs of the smart home, it considers not only the cost of energy purchase from the grid but also the life cost of batteries. The life costs of batteries are calculated based on the relation between the depth of discharge and life time of battery. As the life time of battery depends on the charge and discharge pattern, optimal charge and discharge schedule should consider the life cost of batteries especially when there is more than one battery with different technical characteristics. The proposed algorithm can also be used for optimal selection of size and type of battery for a smart home.

• Journal of the Korean Society of Systems Engineering
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• v.10 no.2
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• pp.33-42
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• 2014

There have been growing demand of Light Rail Transit(LRT) which have a lot of advantages such as construction costs lower than the recent subway, reduction of operational costs, availability of line planning, operation of railway non-beneficiary region, flexible operations of trains, unmanned operation and also have eco-friendly advantages, it is now becoming urban railway systems when environmental issues have been highlighted all over the world. Therefore, RAMS(Reliability, Availability, Maintainability, Safety) Process and activities for effective implementation of light rail transit projects have become a very important element, and also the utilization of computerized tools to perform these more systematically and productively is sought after these days. In this paper, we have presented a plan that can support the RAMS activities by utilizing the function of the computerized SE(Systems Engineering) tool(CORE$^{(R)}$). Through support of the computerized SE tool, it would be possible more clear and efficient railway project execution.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.26-31
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• 2014

High temperature fuel cell system, such as molten carbonate fuel cells(MCFC) and solid oxide fuel cells(SOFC), are capable of operating at MW rated power output. The power output change of high temperature fuel cell imposes the thermal and mechanical stresses on the fuel cell stack. To minimize the thermal-mechanical stresses on the stack and increase the systems reliability, we should divide the power plant configuration to several banks. However, the improvement of reliability in fuel cell power plant system causes an increase of the investment cost, for example, replacement costs, labor costs, and so on. For this reason - the balance between investment and reliability improvement - many studies about the appropriate level of investment have been conducted. In this paper, we evaluate the cost for operation and installation, the benefit for electric energy and thermal energy sales, and the system reliability for several cases : these cases relate with the bank configuration.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.3
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• pp.167-174
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• 2008

Cost related to building equipment accounts for about 85% of the life cycle cost of buildings. Therefore proper selection of air-conditioning system is important for reducing the overall cost of buildings. In this study, medium capacity EHP and GHP for air-conditioning a building with a floor area of 1,200 $m^2$ are compared economically. To consider all the factors of initial and operation costs effectively, an annual equal payment method is proposed. For the initial cost, cost of equipment, construction, installation, electric facility, financial subsidy and tax cut is considered. Cost of basic electricity, energy(electricity and gas), space charge, labor, insurance and repair is considered for the operation cost. Under the assumptions made in this study, overall cost of EHP is less than that of GHP, but this is not absolute and different outcome may result if different assumptions are made. This study is useful for those who are interested in choosing an air-conditioning system that costs less for mid-size buildings with simple calculations.

• Journal of Navigation and Port Research
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• v.28 no.8
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• pp.709-714
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• 2004

This paper first tries to analyze total sea transport costs for the transshipment in Busan Port in comparison with direct transport to 4 Chinese Ports, Dalian, Tinajin, Qingdao and Shanghai, based on vessel operation scenarios. The results found that the transshipment in Busan port for the 4 Chinese ports are more expensive than the direct calling to the 4 ports, which implies that Busan port needs to make compensation as an incentive to the carriers providing transshipment service to it in order to keep their royalty. For the compensation, it suggested a method of calculating the Container Terminal Facilities Leasing Fee to levy additional revenue by port authority.

• Asia-Pacific Journal of Business
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• v.9 no.4
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• pp.99-117
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• 2018

This study has investigated Linear Programming (LP) applications to special decision making problems in managerial accounting with the help of spreadsheet Solver tools. It uses scenario approaches to case examples having three products and three resources in make-and-supply business operations, which is applicable to cases having more variables and constraints. Integer Programmings (IP) are applied in order to model situations when products are better valued in integer values or logical constraints are required. Three cases in one-time-only special order decisions include Goal Programming approach, Knapsack problems with 0/1 selections, and fixed-charge 0/1 integer modelling techniques for set-up operation costs. For the decisions in outsourcing problems, opportunity-costs of resources expressed by shadow-prices are considered to determine their precise contributions. It has also shown that the improvement in work-shop operation for an unprofitable product must overcome its 'reduced cost' by the sum of direct manufacturing cost savings and its shadow-price contributions. This paper has demonstrated how various real situations of special decision problem in managerial accounting can be approached without mistakes by using LP's and IP's, and how students both in accounting and management science can acquire LP skills in their education.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.370-378
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• 2019

In the recent years, various studies have presented stable and economic methods for increased regulations and compliance in sewage treatment plants. In some sewage treatment plants, the effluent concentration exceeded the regulations, or the effluent concentration was manipulated. This indicates that the process is currently inefficient to operate and control sewage treatment plants. The operation and control method of sewage treatment plant is mathematically dealing with a physical and chemical mechanism for the anticipated situation during operation. In addition, there are some limitations, such as situations that are different from the actual sewage treatment plant. Therefore, it is necessary to find a more stable and economical way to enhance the operational and control method. AI (Artificial Intelligence) technology is selected among various methods. There are very few cases of applying and utilizing AI technology in domestic sewage treatment plants. In addition, it failed to define specific definitions of applying AI technologies. The purpose of this study is to present the application of AI technology to domestic sewage treatment plants by comparing and analyzing various cases. This study presented the AI technology algorithm system, verification method, data collection, energy and operating costs as methods of applying AI technology.