• Resources Recycling
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• v.29 no.6
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• pp.125-132
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• 2020

Enrichment possibilities for recovering rare earth elements contained in coal bottom ash generated from domestic circulating fluidized bed combustion (CFBC) were identified. The transport characteristics of the REEs according to the separation and removal of major minerals were evaluated using sieving and leaching process. The main minerals of bottom ash were identified as anhydrite, magnetite, and quartz, and this was confirmed as a 30% of REE content of the world's average coal ash REE value (404 ppm) as a result of the difference in the combustion characteristics of power plants (REE contents in starting material: 123 ppm). More than 90% of the REEs contained in the bottom ash were found to move mainly with magnetite, and less than 10% of the components were found to move with the quartz. Therefore, In order to recover rare earth elements from coal bottom ashes generated from CFBC boiler, it is necessary to select the main rare elements such as magnetite and develop a pretreatment and concentration process.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1158-1167
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• 2015

In this paper, a new hybrid DC-DC converter is proposed for electric vehicle 3.3 kW on-board battery charger applications, which can be modulated in a phase-shift manner under a fixed frequency or frequency variation. By integrating a half-bridge (HB) LLC series resonant converter (SRC) into the conventional phase-shift full-bridge (PSFB) converter with a full-bridge rectifier, the proposed converter has many advantages such as a full soft-switching range without duty-cycle loss, zero-current-switching operation of the rectifier diodes, minimized circulating current, reduced filter inductor size, and better utilization of transformers than other hybrid dc-dc converters. The feasibility of the proposed converter has been verified by experimental results under an output voltage range of 250-420V dc at 3.3 kW.

• Journal of Institute of Convergence Technology
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• v.3 no.1
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• pp.19-23
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• 2013

This study is concerned with air-conditioning system in use of thermoelectric device. It is introduced that the well designed structures for better cooling & heating performance with high efficiency. And also it is performed that the system performance test of four types trial products for the use of hybrid commercial vehicle. System performance is affected by many component parts, especially heat sink design & power control method. It is applied that dual extrusive fin tube with buffer zone for the effective radiating of circulating liquid in tube. And also it is applied that power supply method with constant-current system. It is attained that system cooling capacity is 1.2kW, COP is 0.95.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.353-358
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• 2002

In this paper, improved ZCS-PWM boost converter is proposed. The proposed converter eliminates additional conduction loss of a main switch by flowing circulating current oかy through an auxiliary switch. The operation modes of proposed converter are explained. And design procedure of resonant parameters is established. Experimental results are presented to verify the theoretic analysis of the proposed converter.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1492-1494
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• 2015

분산전원 연계기준에 따라 변압기 1차 중성점을 접지운전시 Y-Y-3Limb, $Y-{\Delta}$결선방식은 비대칭 계통전압에 의해 순환전류가 발생된다. 이러한 순환전류는 상별 전류에 영향을 주어 보호계전기 오동작 및 전력량계 오차를 발생시킨다. 따라서 순환전류로 인한 전력계산의 문제를 해결하기 위해 신동파워이론을 만들었다. 본 이론의 핵심은 비대칭 3상 전압과 변압기 결선 및 구조에 의해 발생되는 영상 임피던스(R+jX) 해석을 통해 중성선의 순환전류를 계산하였다. 따라서 정확한 전력계산을 위해 순환전류에 의해 발생되는 상별전류를 보정하는 새로운 이론을 소개 하고자 한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.188-192
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• 2000

This paper presents a novel prototype of soft-switching PWM Full-bridge converter which incorporates active power switches in series with each rectifier diode in transformer secondary side. Switching and conduction losses of all the switches and devices are reduced as well as commutating current and circulating current flowing through transformer as compared with conventional converter. And duty ratio of primary switches is constant for maximum voltage conversion ratio. But this converter can be varied output by duty ratio of secondary switches. Operation principles basically the same as that of the PWM Full-bridge converter published previously. The operating characteristics of this converter are illustrate and discussed including the simulated analysis.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.503-508
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• 2005

An advanced Research Reactor (ARR) consists of an open-tank-type reactor assembly within a light water pool and generates thermal power of 20 MW. The thermal power is including a fission heat in the core, a fuel generated heat temporary stored in the pool, a circulating pumps generated heat and a neutron reflecting heat in the reflector vessel of the reactor. In order to remove the heat load, the primary cooling system will be installed. In this study, the conceptual design of the primary cooling system has been carried out using a design methodology of HANARO within a permissible range of safety. As results, it has been established that the conceptual design of the primary cooling system including design requirements, performance requirements, design restrictions, system descriptions and system operation to maintain the system functions.

• Journal of Power System Engineering
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• v.5 no.1
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• pp.57-63
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• 2001

In the present study, an interactive mode of the computing system has been developed for the hydraulic analysis of the circulating waters in the industrial pipings. The system consists of three separated modules, which are linked together with common graphical user interfaces. Application to the design of the cooling sea-water system for the ships was demonstrated to be very reliable and practical in support of design activities.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.397-397
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• 2011

In a low aspect ratio (LAR) tokamak reactor with a superconducting toroidal field (TF) coil, the radial build of TF coil and the shield play a key role in determining the size of a reactor. For self-consistent determination of the reactor components and physics parameters, a system analysis code is coupled with one-dimensional radiation transport code. Conceptual design study of a compact superconducting LAR tokamak reactor with aspect ratio less than 2.5 was conducted and the optimum radial build was identified. It is shown that the use of an improved shielding material and high temperature superconducting magnets with high critical current density opens up the possibility of a fusion power plant with compact size and small re-circulating power simultaneously at low aspect ratio, and that by using an inboard neutron reflector instead of breeding blanket, tritium self-sufficiency is possible with outboard blanket only and thus compact sized reactor is viable.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.423-429
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• 2006

Recently, the high frequency isolated boost DC/DC converter has been widely used for the PCS (Power Conditioning System) system because of its small size and low cost. However, the high frequency isolated boost DC/DC converters applied the conventional voltage-fed converter and current-fed converter have the problems such as the high conduction losses and the surge voltage due to the high circulating current and the leakage inductance, respectively. To overcome this problems, in this paper the secondary LLC resonant converter is proposed, and the experimental results of the secondary LLC series resonant converter for boost DC/DC converter are verified on the simulation based on the theoretical analysis and the 700W experimental prototype.