• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.1
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• pp.80-90
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• 2014

This paper suggests loss analysis and calculation methods for efficiency improvement of power conversion equipment in detail. The detailed loss analysis and calculation has been conducted for 3.3kW On-board Battery Charger considering temperature condition. The validity of the analysis and calculation method is verified by simulation model.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.371-375
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• 1995

This paper presents equipment for charging and discharging with high power factor and high efficiency. This equipment is consisted of $3{\phi}$ SPWM AC/DC converter for improving input current waveform and input power factor, and bidirectional DC/DC converter for electric isolation in the DC link Part. Therefore, Input power factor and the total efficiency in the proposed system can be increased more than in the conventional phase-controlled thyristor charging-discharging System.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.12
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• pp.992-998
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• 2014

Acoustic radiation efficiency is one of the important factors in the prediction of underwater radiated noise of ships. A ship has much equipment to operate successful mission in a ship. Most of equipment is running simultaneously as multi-excitation and becomes the source of underwater radiated noise. In many cases of multi-excitation, phase difference between multi-excitation is not considered. Because vibration response under multi-excitation is the vector sum of each single excitation, acoustic radiation efficiency based on surface velocity field can be affected by phase of excitation. In this study, acoustic radiation efficiency of a plate on air and a stiffened cylindrical model in water under multi-excitation with phase difference is investigated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.10
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• pp.99-103
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• 2019

Recently, as the high-precision machinery industry has developed rapidly, peripheral equipment has been developed to improve machining efficiency. Peripheral equipment for machining includes cooling units, housings, oil separators, and much more. Oil, such as cleaning and cutting fluids, is used for machining. When waste oil is reused, the contamination of the workpieces and reduction in machining accuracy are generated by the waste oil, including sludge. Therefore, the development of an oil separator is necessary for efficiently separating oil, water, and sludge. The purpose of this study is to analyze the oil separation efficiency and flow characteristics of a high-speed centrifugal separator according to the rotation velocity and diffusion plate. The oil separation efficiency and flow characteristics were analyzed using hydrodynamic theory and computational fluid dynamics (CFD). The results of this study will be used as basic data for the development of a high-speed centrifugal separator.

• Health Policy and Management
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• v.22 no.1
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• pp.65-84
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• 2012

Because of the rising healthcare costs, there is a growing need for developing efficiency indicators for medical resources use and measuring efficiency of healthcare providers and healthcare systems using them. In this study, we aimed to develop efficiency indicators for medical resources use by means of Delphi technique. We systematically reviewed the existing measures of medical resource use. Thirty nine indicators were selected as a candidates across the six domains: medical personnel, medical equipment, medical facilities, ethical management, resource efficiency, and drug use. To develop efficiency indicators with professional consensus, a 2-round Delphi survey was conducted among 29 professional experts. The following indicators were selected based on the Delphi survey results: adjusted number of the patient per day and level of the nurse number medical personnel in medical personnel domain; the number of the scan a professional physician and the quality of the scan in medical equipment domain; bed utilization rate in medical facility domain; drug price reported pharmaceutical price by medical institutions, medical fee billing transparency, and medical care appropriateness in ethical management domain; costliness index in resource efficiency domain; and utilization of high cost drug and items per prescription in drug use domain. The efficiency indicators could provide valid information about efficiency of healthcare providers and healthcare systems with respect to their resources use and facilitate policies to improve their efficiency.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.154-155
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• 2014

Small photovoltaic equipment spreads to the detached house owing to the support of government. This study analyzed the payback period of small photovoltaic equipment, and presented a plan of spreading PV equipment by electricity consumption according to the results. The results of payback period analysis showed that a household of 500kWh or above in the average monthly electricity consumption could produce an economic effect without the subsidies of government, and a household of 300kWh or above could secure economical efficiency in case of receiving the subsidies of government and municipality. However, it was shown that the economic effect was not large in case of a household of less than 250kWh. Therefore, the analysis showed that it would be necessary to be supported by additional subsidies or to develop a new supporting policy with regard to a household of less than 250kWh.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.47-52
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• 2005

Recently, power conversion equipment increased rapidly makes a lot of harmonics. Thus, it is growing that wrong operation and break down of sensitive devices. There are two kinds of causes of harmonics. One of them is lots of power conversion equipment as modem controller, inverter, converter and SWS(Switching Mode Power Supply). Another is nonlinear operating machines as transformer and motor. The more nonlinear loads like them grow, the more serious problems as harmonic current to source and low power factor because of increasing reactive power grow. It is installed for reactor and L-C Filter to decrease harmonic in general. This paper analysis and compares two of characteristics and harmonic from reactor and L-C Filter with operation of induction motor and power conversion equipment. In the result, L-C Filter more improves unbalance rate and THD than reactor.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.669-670
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• 2015

Efficient management of the construction heavy equipment is required to reduce the rate of carbon emissions and on-site accidents. The intelligent excavation system (IES) will improve the construction quality and productivity through information technologies and efficient equipment operation, especially in large earthwork projects. Three-dimensional digitized ground data should be required for identifying the path of heavy equipment and work-site environment. Rapid development of terrain laser scanners (TLS) is more readily to acquire the digital data. This study suggests the '3D ground terrain processing platform (3DGTPP)' including data manipulating module and analyzing module of the scanned data for intelligent earthmoving equipment operation. The processing platform consists of six modules, including scanning, registering, manipulating, analyzing, transmitting, and storing. 3D ground terrain processing platform presented in this study will provide fundamental information for intelligent excavation system (IES), which will increase the efficiency of earthworks and safety of workers in significant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.392-397
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• 2013

To fulfill the demands concerning energy efficiency for zero energy buildings, various technologies of architects and engineers are required. This study aims to estimate the thermal performance of heat source equipment in which part load characteristics are considered in an office building. Overestimation of heat source equipment was reviewed through literature survey, and heating and cooling loads depending on the capacity and division of the equipment were analyzed through a simulation program (DOE-2.1E). The conclusions gained from this study are as follows; 1) The more the division of equipment, the less the heating and cooling energy consumption. 2) When a large item of equipment is divided into two small items of equipment, the optimum application rate showed as 5:5 for chiller, and 7:3 for boiler, respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.234-235
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• 2015

In South Korea, small photovoltaic equipment is increasingly adopted in more detached houses on the constant basis. With this broader use of small photovoltaic equipment, its systematic maintenance becomes all the more necessary. However, photovoltaic facility maintenance has been concentrated solely on large-scale solar energy generation plants in the country while hardly covering smaller facilities. In this research, the JEM rule and extant maintenance company services were analyzed to develop a proper maintenance model for small photovoltaic equipment. The maintenance service procedures designed herein are as follows: A small photovoltaic equipment user chooses a maintenance company and signs a contract. Once a contract is made, the Korea Energy Management Corporation provides a certain kind of incentive to the company. The company provides maintenance service to the user and receives a service fee. If such a maintenance service model is in place, small photovoltaic equipment efficiency is expected to increase and users could receive systematic maintenance services. Also the new creation of small photovoltaic equipment maintenance service would form a new market to generate more jobs for the society.