• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.474-479
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• 2016

As the Eco-energy is recently required, electrical energy is fast increased. Several induction heating methods are attractive for Eco-energy and energy saving. In this paper, electrical fan heater was designed and developed with new concept for energy saving by electromagnetic induction heating. Proposed system was composed of three module, blast part, induction heating part and power transformation part. Induction heating method was adapted for heating and the resonant inverter was used for increasing of the power transformation efficiency. Full-bridge resonant inverter was adopted to resonant inverter. This system was composed of induction heating part made with metal(SUS 40 series), and power transformation part made with rectifier module, filter module and resonant inverter. From these results, the proposed new electric heater could be saved the energy from faster increasing the temperature compared to commercial gas and other electric heater. This electrical fan heater is possible to be used in field of home, commercial and agricultural area for eco-energy saving heater.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.294-295
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• 2018

유도가열은 전자기 유도 현상을 이용하여 금속체를 직접 가열하는 방식이며 높은 변환 효율로 전기에너지를 열에너지로 변환할 있다. 이로 인해 금속의 단조, 용해, 표면경화, 풀림 등 여러 응용분야를 통해 철강 및 기계 산업에 기여하고 있다. 단조용 유도가열기 전원장치는 높은 전력용량을 사용하여 주로 SCR을 이용한 위상제어 정류기를 적용한다. 하지만 입력단의 저 역률 및 전류의 THD가 높은 단점을 가진다. 따라서 본 논문에서는 이러한 단점을 보안하기 위해 단조용 유도가열 작업에 맞는 인터리브드 방식의 벅 컨버터와 전류원 인버터를 사용한 고효율 유도가열 전원장치를 제안한다.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.345-346
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• 2017

유도가열은 전자기 유도현상을 이용하여 금속체를 직접 가열하는 방식이므로 높은 변환 효율로 전기에너지를 열에너지로 변환시킬 수 있다. 현재 널리 사용되고 있는 단조용 유도 가열 전원 장치는 주로 위상제어 정류기를 이용한다. 하지만 입력단의 저 역률 및 입력전류 THD가 높은 단점을 가진다. 따라서 본 논문에서는 이러한 단점을 보안하기 위한 3상 다이오드 정류기와 벅 컨버터를 사용한 고 역률 유도가열 전원 장치를 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.2
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• pp.223-230
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• 1998

This paper describes a phase-shift pulse-width modulation and pulse-frequency modulation series resonant high-frequency inverter using IGBT(Insulated-Gated Bipolar Transistor) for the power control of high-frequency induction heating using neuro-fuzzy, which is practically applied for 20KHz~500KHz induction-heating and melting power supply in industrial fields. The adaptive frequency tracking based phase-shifting PWM(Pulse-Width Modulation) regulation scheme is presented in order to minimize switching losses. The trially-produced breadboards using IGBT are successfully demonstrated and discussed.

• Plant Journal
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• v.15 no.2
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• pp.56-61
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• 2019

In this study, the failure analysis of the internal tube occurred in the high pressure feedwater heater for power generation boiler of 500 MW supercritical pressure coal fired power plant was investigated. I suggested a prediction model that can diagnose internal tube failure by changing the position of level control valve on the shell side and the suction flow rate of the boiler feedwater pump. The suggested prediction model is demonstrated through additional cases of feedwater system unbalance. The simultaneous comparison of the shell side level control valve position and the suction flow rate of the boiler feedwater pump compared to the normal operating state value, even in the case of the high pressure feedwater heater for the power boiler, It can be a powerful prediction diagnosis.

• Applied Biological Chemistry
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• v.41 no.6
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• pp.431-436
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• 1998

The optimum ohmic heating condition of apple juice was investigated with model solution. The temperature rise of model solution was found to be $7.8,\;21.0,\;47.4^{\circ}C/min$ when the distances between electrodes were 29, 22, and 17mm, respectively. The heating rate increased proportionally with the numbers of electrode pairs, 1 to 3 and highly dependent on applied voltage. The heating rate was not affected by the frequencies ranged from 60 Hz to 60 KHz and the wave form of applied alternating electric current. The apple juices prepared by ohmic heating sterilization revealed similar physicochemical properties to that by commercial sterilization.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.553-561
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• 2010

A medium-scale helium loop that can simulate a VHTR (very-high-temperature reactor) is now under construction at the Korea Atomic Energy Research Institute. The heaters of the test helium loop electrically heat helium fluid up to $950^{\circ}C$ at pressures of 1 to 9 MPa. To optimize the design specifications of the experimental helium loop, the conjugate heat transfer in the high-temperature helium heater was analyzed by performing a CFD simulation. The analysis results indicate that the maximum temperature does not exceed the allowable limit. It is confirmed that the thermal characteristics of the loop with the given geometry satisfy the design requirements.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.805-808
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• 2003

기존에 적용중인 유전가열 합성수지 접착기술의 경우 진공관 소자를 사용하여 10MHz 대역 이상의 스위칭 주파수를 사용하고, 유전손실이 비교적 높은 PVC 소재에 제한적으로 적용해 왔다. 다른 합성수지 소재에 비해서 유전손실이 낮은 친환경적인 소재에 대해서는 적용이 어려운 기술인 관계로 최근들어 부각되는 친환경적 소재의 적용 확대로 인하여 기존 유전가열 방식의 접착기술은 한계에 접하고 있다. 본 논문에서는 고주파 유도가열 관련 기술을 응용하여 친환경적인 합성소재의 직접가열의 문제점을 간접가열에 의한 온도제어를 적용하여 고주파 유도가열 접착기를 설계하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.145-145
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• 2015

유도가열 코일 내부의 물질에 비접촉식으로 에너지를 전달하기 위하여 유도가열 코일에는 고주파 대전류를 투입하게 된다. 이러한 결과로 코일 자체에도 상당히 높은 수준의 발열이 발생하게 된다. 따라서 실제적으로 코팅물질의 발열을 위하여 전달되는 에너지 이외에 소모적으로 사용되는 에너지가 어쩔 수 없이 코일에 존재하게 된다. 이는 전자기코일의 효율을 낮추는 역할 뿐만 아니라 안정적인 운전을 저해하는 역할을 하게 된다. 본 논문에서는 전자기 및 온도 해석을 통하여 설계 제작된 유도가열 코일을 투입 전류를 바꾸며 실험하여 각 전류 투입시 코일에서의 발열량 및 온도 측정 결과를 해석 결과와 비교하여 유도가열 코일에 대한 평가를 수행 하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1313-1320
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• 1993

Flow patterns inside the riser section and the effects of the heater inlet-and exit-restrictions, liquid charging level and the heater inlet subcooling on the flow characteristics inside an open two-phase natural circulation loop were studied experimentally. Three basic circulation modes were observed ; periodic circulation (A)(flow oscillations with incubation(no boiling) period), continuous circulations(stable operation mode with no flow oscillations), and periodic circulation (B) (flow oscillations with continuous boiling). The circulation rate increases and then decreases with the increase of the heating rate and the maximum circulation rate appears with the continuous circulation mode. The decrease of the inlet-restriction or the increase of the exitrestriction destabilizes the system. When the liquid charging level or the inlet subcooling decreases, the continuous circulation mode starts at the lower heating rate and the system is stabilized.