• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.774-777
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• 2005

In this paper, a constant frequency phase shifting PWM controlled voltage source full bridge-type series load resonant high-frequency inverter using the IGBT power modules is presented for innovative consumer electromagnetic induction heating applications such as a hot water producer, steamer and super heated steamer. The full bridge arm side link passive quasi-resonant capacitor snubbers in parallel with the each power semiconductor device and high frequency AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is discussed and evaluated on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency soft switching PWM inverter topology, what is called class DE type. including the variable-power variable-frequency(VPVF) regulation function can expand zero voltage soft switching commutation range even under low output power setting ranges, which is more suitable and acceptable for induction heated dual packs fluid heater developed newly for consumer power utilizations. Furthermore, even in the lower output power regulation mode of this high-frequency load resonant tank high frequency inverter circuit it is verified that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.3
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• pp.268-279
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• 2007

The reliability of cold-bonding repair technique of carbon-fiber reinforced plastics (CFRP) laminates, often used as a temporary repair for the airplane maintenance, has been evaluated during cyclic loading and localized heating by nondestructive methods. Major concern was given to the evolution of damage after repair in the form of delaminations due to localized heating and cyclic loading combined. An area of interest both on the specimen repaired by cold-bonding and the specimen without repair where delaminations were induced by localized heating and cyclic loading was monitored by acoustic emission (AE) testing and further examined by pitch-catch low-frequency bond testing, and pulse-echo high-frequency ultrasonic testing. The results showed that the reliability of cold-bonding repair would be significantly reduced by the localized heating and cyclic loading combined rather than by the cyclic loading only. AE monitoring appeared to be an effective and reliable tool to monitor the integrity of temporarily repaired CFRP laminates in terms of the structural health monitoring (SHM) philosophy.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.55-58
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• 2007

Titanum and its alloys have been used as the important materials of eyewear frame due to its light weight, mechanical strength and corrosion resistance. This study investigates hardness and microstructures of titanum alloy groove wires in according with heating time by high frequency induction heating. Because of increase of grain size by the growth of heating time, hardness of ${\beta}-Ti$ has reduced. Hardness of Ti-325 reduced until 2 sec and rapidly increased at 3 sec by high frequency induction heating. It is observed that hardness of Ti-325 reduces by the increase of the grain size until 2 sec and suddenly increased by the development of the detailed ${\alpha}+{\beta}$ lamella at 3 sec.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1168-1170
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• 2000

A half bridge time sharing type high frequency resonant inverter to give VVVF function in the inverter used as power source of induction heating at high frequency is presented in this paper, this paper also realize the output control of independence irrespective of the switching frequency using Phase-Shift. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operation and the its characteristics are estimated by the parameters, such as switching frequency, the variation of phase angle(${\varphi}$) of Phase-Shift. It is certain that the proposed circuit will be used and expanded in the high frequency power supplies like induction heating systems.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.04a
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• pp.43-43
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• 2006

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.169-171
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• 2005

In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM series load resonant high frequency inverter with two auxiliary edge resonant lossless inductor snubbers is proposed for small consumer induction heating appliances. The operation principle of this high frequency inverter is described using the switching mode equivalent circuits. The practical effectiveness of the newly proposed soft switching inverter are discussed as compared with the conventional soft switching high frequency inverters based on simulation and experimental results from an application point of view.

• Elastomers and Composites
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• v.44 no.4
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• pp.358-365
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• 2009

High-frequency induction is an efficient way to rapidly heat mold surface by electromagnetic induction. In the present work, high-frequency induction heating is applied to injection molding of a mobile phone cover in order to eliminate weldlines by efficiently raising the mold temperature. Through the induction heating experiments, the maximum temperature of $143^{\circ}C$ is obtained on the mold surface in 3s of heating, which is higher than the glass transition temperature of the resin material. An injection molding experiment is then performed with the aid of induction heating, from which we can successfully remove all the weldlines of the mobile phone cover. The effect of induction heating conditions such as the heating power and the heating time on the surface appearance is experimentally investigated.

• Journal of Power Electronics
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• v.5 no.4
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• pp.272-281
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• 2005

In this paper, a simple power control scheme for a constant frequency Class-D inverter with a variable duty cycle is proposed. It is more suitable and acceptable for high- frequency induction heating (IH) jar applications. The proposed control scheme has the advantages of not only wide power regulation range but also ease of control output power. Also it can achieve a stable and efficient Zero-Voltage-Switching (ZVS) in a whole load range. The control principles of the proposed method are described in detail and its validity is verified through simulated and experimental results on 42.8kHz IGBT for induction heating rated on 1.6kW with constant frequency variable power.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.124-128
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• 1999

The object of the present study is to obtain a 20[kHz], 10[kW] rating, high efficiency induction heating system by high frequency serises-resonant inverter. Proposed is a topology that minimize a reactive power, by which direct iOIrt voltage is variable corresponding to the variation of the load, heated-object, and by which the switching of inverter is forced to follow a resonant frequency. And assured that the power foctor of the inverter in a induction heating system is proper about O.96 through the simulation and results.esults.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2064-2066
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• 1998

The development of the high-frequency induction-heating for 1800kW power range intend to make localization at forging and rolling mill part by technical innovation. And, the development makes to increase our's competitive power at technique, quality and cost. This paper describes the heart of high-frequency induction-heating technique, switching technique, a few problem in common using as an unsatisfied technique, load adjustment technique, system control, diagnostic system and auto-interface etc.