• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.189-194
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• 2009

In a gas engine based cogeneration system, heat is recovered from two parts, which are jacket water and exhaust gas. The heat from the jacket water is often recovered by a plate type heat exchanger and used for the room heating and/or hot water supply. Depending on the operating conditions of engine and heat recovery system, there should be imbalance in the flow rate and supply pressure between engine and heat recovery side of the heat exchanger. The imbalance cause the deformation of the plate, which affects the pressure drop characteristics. In the present study, the pressure drop inside the heat exchanger has been investigated in a 1/5 scaled test rig and compare with the experimental correlations, which are used for the design.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.374-381
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• 2005

The ability to provide quality power has become a significant issue in power systems. The main causes of poor power quality are harmonic currents, poor power factor, supply-voltage variations, etc. A technique of achieving both active current distortion compensation, power factor correction and also mitigating the supply-voltage variation (sag or swell) at the load side is presented in this paper. The operation and rating issues of the proposed Single-phase Unified Power Quality Conditioner are also highlighted. To reduce the total cost while simultaneously increasing the performance, the system is fully digitally controlled using the fixed-point TMS320F240 digital signal processor. The performances of the UPQC, which is composed by shunt and series PWM controlled-converters, have been verified on a laboratory prototype.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.57-60
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• 2008

As the technology of a large scale battery have advanced, it's application to the electric power network have been active in foreign country. By providing the electric power energy stored in the electric power storage system when needed, there are many advantages that it is able to reduce the gap between the electric power demand and supply for day and night to increase capacity factor, to upgrade the electric power quality degraded from the unbalance between power demand and supply and to compensate the fluctuation of wind power plant and photovoltaic power generation. In this study, the current application of electric power storage system using battery is introduced in detail, and I have thought out it's application fields based on the foreign examples. These are demand side response, upgrade of the power quality, stabilization of fluctuation of renewable energy and distributed generation for filling elapse.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.171-172
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• 2018

The purpose of this study is to confirm the adhesion performance of the three - dimensional forming fiber panels by the dimensional forming angle. As a result of applying the three dimensional surface shape to the back side of the fiber panel and testing the adhesion strength by the three dimensional forming angle, it was confirmed that the bonding strength of the specimens to which the dimensional molding was applied was higher than that of the non dimensional molding. In addition, the highest adhesion strength was confirmed in a specimen having a three-dimensional forming angle of 70 °.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.898-904
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• 2012

This paper presents a ride-through skill of PMSG wind turbine system under the distorted and unbalanced grid voltage dips. When voltage dips occur in the grid, pitch control and generator speed control as well as a parallel resistor of DC-link help to keep the turbine's safety. Modern grid code requires a wind turbine to supply reactive currents to help voltage recovery after grid faults clearance. In order to supply reactive currents to the grid in case of the distortedly unbalanced grid voltage dips, a special PLL is needed to control the grid side converter and to regulate the grid voltages symmetrically. The proposed method is applied to 2MW multi-pole PMSG wind turbine system, and verified by simulation.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.30-31
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• 2010

Filament power supply (FPS) for neutral beam injection (NBI) consists of an insulation type is a device that heats the interior of Tokamak. The input/output specifications of FPS are 3-phase AC 200[Vpeak] and DC16V/300A respectively. A conventional FPS is composed of a 3-phase diode rectifier with DC-link, a H-bridge DC/DC converter, a high frequency transformer, a secondary rectifier and a LC-filter. In this paper, to improve the efficiency of PSFB DC/DC converter it is substituted IGBT devices instead of diode rectifier in secondary side. The proposed method is verified by computer simulation and experiment result.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.49
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• pp.11-21
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• 1999

The purpose of this study is to present the method to select optimal size for the industrial products which are closely related to human's body size. For this purpose, human factors such as body characteristics, body features, and preference in product selection which needs to be considered in setting standards were analyzed. This analysis is to select optimal size to minimize losses caused by the difference of size between demand by the customers and supply from the manufacturers. Using loss function, repetitive calculation process algorithm by using bisearch method was applied in selecting the sizes of demand and supply which minimize the total expected losses. For cumulative normal distribution probability, IMSL routine DNORDF was used. In case study, comparison has been made between the result which was calculated using presented algorithm and the results calculated by the process currently used by KS and ISO by measuring aged women's body size in human factors side and sorting them through the factor analysis and cluster analysis for feature factor extraction. Thus, they can be used as a basis for establishing industrial product standards.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.932_933
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• 2009

A technology based on thyristors will be used to manufacture the super-conducting coil AC/DC converters because of the low ratio of cost over installed power compared to a design based on GTO or similar technology. But phase-controlled converter suffers from fundamental disadvantage. They inject current harmonics into the input ac mains due to their nonlinear characteristics, thereby distort the supply voltage waveform, and demand reactive power from the associated ac power system at retarded angles. To overcome this disadvantage, in the case of two series converters at the DC side, connected to the same step-down transformer, apply for the sequence control. It is the most simple and efficient way to reduce the reactive power consumption at low cost. Analytical sequence control algorithm is suggested, the validity of the proposed scheme has been verified by experimental results with the small-scaled International Thermonuclear Experimental Reactor (ITER) Power Supply to minimize reactive power consumption.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9113-9116
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• 2014

Purpose: : To assess the clinic value of application of laparospic ultrasonography (LU) in partial nephrectomy of small renal cell carcinoma. Materials and Methods: From 2007 to 2011, 28 small renal cell carcinoma patients in ou clinic underwent laparoscopic partial nephrectomy with LU. For comparison with preoperative conventional ultrasound and CT, we collected ultrasonic performance of the affected side kidney, renal tumor location, size, echo change, blood supply situation and the relationship with the surrounding tissue. Results: LU could more clearly show the tumor interior structure and blood supply, as well as the relationship with the surrounding tissue. It also can provided doctor assistance with real-time tumor resection, reducing operative complications. Conclusions: LU can clearly show tumor internal structure and blood supply, which is helpful for explicit diagnosis. Moreover, it supplies accurate information for surgeons and assists surgery. Therefore LU has an important guiding value in partial nephrectomy for small renal cell carcinoma.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.29-37
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• 1999

Ventilation of the marine engine room is very important for the health of the workers as well as the normal operation of machines. To find proper ventilation conditions of this engine room, numerical simulation with standard k-${\epsilon}$ model was carried out. In the present study, the marine engine room is separated to two floors with porus horizontal partition and considered as a closed space with a heat source and forced ventilation ducts. The porosity of horizontal partition is found to be important. For the engine room with 2 supply ports & 2 exhaust ports, the increasing of the porosity of horizontal partition is effective to reduce the recirculation flow zone in the second floor. When the engine room is ventilated with three supply air ports & one exhaust port, the increasing of the porosity of horizontal partition is effective to reduce the recirculating flow zone in the exhaust air area, but there is a possibility of local extreme heating at the lower side of engine near bottom.