• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.9-16
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• 2010

In this paper, we have proposed a new dimmable magnetic ballast for HID(High Intensity Discharge) lamps consisted of AC switches to variate inductance value by using Silicon Controlled Rectifiers and the isolated zero current detector on inductor. Conventional dimming ballast has used relays or Solid State Relays in AC switches. However, a relay is difficult to zero current switching, because it has long operating time(10[ms]), and price competitiveness of SSR is very low. The proposed AC switches are suitable to switch at zero inductor current and it is accurately detected by using a opto-coupler. SCR is cheaper than SSR, and it is suitable to switch at zero inductor current because SCR is automatically turned off under holding current at no gate signal. Operating principles, simulation results and experimental results of the proposed ballast are described.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.12-20
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• 1998

The non-uniform leaky wave structure of the slits in a parallel-plate waveguide is analyzed from the viewpoints of transmitting(receiving) leaky wave antenna and grating coupler. Period and slit width are simultaneously varied along the leaky wave structure to construct the leaky wave structure with a specific distribution of complex propagation constant. Some results for the equivalent magnetic current distributions over the slits and the radiation characteristics of the leaky wave structure with various source(equivalent magnetic current) distributions such as Gaussian, uniform, cosine, cosine-squared, and Taylor distributions are given and compared with each other.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.272-273
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• 2005

전력선 통신을 위한 커플러용 자심재료의 열처리 온도증가에 따라 결정이 성장하여 인덕턴스는 증가 하였고, $550^{\circ}C$ 이상에서는 포화점을 나타내었다. 커플러는 자심재료의 투자율이 높을수록 커플러의 저주파 대역의 신호전승 특성이 우수하게 나타났지만, 주파수 증가에 따라 급격히 저하하는 불안정한 특성을 나타내었다. 그리고 절단면 사이의 Air gap 증가에 따라 10 MHz이하의 주파수 대역에서 신호전승특성이 급격히 감소하였고, 허용전류는 직선적으로 증가하였으며 Air gap이 $600{\mu}m$이상일 때 300A의 전류에서 특성을 발휘하였다.

• Journal of Power Electronics
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• v.18 no.1
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• pp.195-203
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• 2018

In the variable speed Wind Turbine based on ElectroMagnetic Coupler (WT-EMC), a synchronous generator is coupled directly to the grid. Therefore, like conventional power plants, WT-EMC is able to inherently support grid frequency. However, due to the reduced inertia of the synchronous generator, WT-EMC is expected to be controlled to increase its output power in response to a grid frequency drop to support grid frequency. Similar to the grid frequency support control of Type 3 or Type 4 wind turbine, inertial control and droop control can be used to calculate the WT-EMC additional output power reference according to the synchronous generator speed. In this paper, an experimental platform is built to study the grid frequency support from WT-EMC with inertial control and droop control. Two synchronous generators, driven by two induction motors controlled by two converters, are used to emulate the synchronous generators in conventional power plants and in WT-EMCs respectively. The effectiveness of the grid frequency support from WT-EMC with inertial control and droop control responding to a grid frequency drop is validated by experimental results. The selection of the grid frequency support controller and its gain for WT-EMC is analyzed briefly.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.258-260
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• 2006

비정질 합금재료와 페라이트를 사용하여 비접촉식 커플러를 제조하여 각각의 재료가 적용가능한 범위를 규명하고자 하였다. 비정질 합금재료에 비해 페라이트는 안정적인 특성을 발휘하는 주파수 대역이 좁으며, 낮은 포화자속밀도로 인해 내전류 특성이 떨어졌다. 즉 페라이트는 20 MHz 이하의 주파수 대역과 비정질 재료가 적용되는 선로보다 유입전류가 낮은 전력선에 적용 가능할 것으로 보인다.

• Journal of Power System Engineering
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• v.20 no.3
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• pp.22-28
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• 2016

Energy consumption rapidly increases with industrial development. therefore an interest in the efficiency of various power converters is increasing. Especially, the field of high-efficiency small motors widely distributed for industrial and family use is considered a very important field in terms of efficient energy usage, and accordingly, in the field of small electric equipment, the use of BLDC that allows high-efficiency drive in an inductor gradually increases. However, for the BLDC drive, information on the position of the rotor is essential. Both methods using a magnetic encoder and an optical encoder to detect the information on the position of the rotor obtain the information by three position sensitive devices, and if any one of these position sensitive devices fails to function, no positional information can be obtained, so there is a limitation in implementing a position sensor with high reliability. In the paper, proposes a new type of encoder that can obtain the positional information on the position of the rotor using a single position sensor in order to overcome the issues that it has to use numerous signal flows and that the reliability is reduced for the acquisition of positional information generated by using multiple position detectors. The encoder in the proposed method replaced the function of generating positional information from multiple sensors with the shape of the encoder plate and the capture function of MICOM. In order to verify the validity of the position detection technique by the proposed encoder, a prototype was produced, and an experiment using the capture function of DSP was conducted through this.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.148-152
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• 2005

A novel interferometric isolator has been proposed and designed to fabrticate waveguide magnetooptic isolator operating at a wavelength of $1.55{\cal}um$. The device consists of MMI (multimode interference) couplers and has a magnetooptic guiding layer with different layer structure in arms of the inteferometer. The layer structures in the arms of inteferometer are $HfO_2/CeY_2Fe_5O_{12}/NOG$ and $SiO_2/CeY_2Fe_5O_{12}/NOG$, respectively. This configuration give rise to different nonreciprocal phase shift. In consequence, the isolator operates under a unidirectional magnetic field. The optimized structure of the isolator was determined by a 3D beam propagation method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.4
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• pp.25-30
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• 1971

Fabrication and measurements of the magnetically tunable YIG band pass or stop filter at X-band are discussed. Using two YIG spheres located at the region of r-f circularly polarized magnetic field between the strip lines, the pass or stop characteristics of the filter are obtained. In the case of band stop, the output level is typically 25db lower than the input power. Contrarily for the pass band, the pass band level is 22db higher than the stop frequency region. The experimental results are in good agreement with the theoretical values of FMR. Further it is shown that the structure can be used for a directional coupler.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.05a
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• pp.171-175
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• 1995

Semiconductor diode lasers that can generate one watt or more of optical energy for tens of milliseconds (quasi continuous wave) are now readily available. Several researchers have demonstrated that this power level, when properly coupled, can reliably initiate pyrotechnic mixtures. This means that the initiator containing the pyrotechnic can be protected against inadvertent initiation from electromagnetic radiation or electrostatic discharge by a conducting Faraday cage surrounding the explosive. Only a small dielectric window penetrates the housing of the initiator, thereby eliminating the conductors necessitated by a bridgewire electroexplosive device. The diode laser itself, however, functions at a low voltage (typically 3 volts) and hence is susceptible to inadvertent function from power supply short circuits, electrostatic discharge or induced RF energy. The rocket motor arm-fire device de-scribed in this paper uses a diode laser, but protects it from unintentional function with a Radio Frequency Attenuating Coupler (RFAC).The RFAC, invented by ML Aviation, a UK company, transfers power into a Faraday cage via magnetic flux, thereby protecting the diode, its drive circuit and the pyrotechnic from all electromagnetic and electrostatic hazards. The first production application of a diode laser and RFAC device was by the Korean Agency for Defense Development.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.251-259
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• 2009

In this paper, a contactless power supply using half-bridge series resonant converter that achieves ZVS operation of main switches and ZCS operation of secondary side diodes is proposed. Since the proposed contactless power supply using half-bridge series resonant converter operates with lower switching frequency than the resonant frequency, it can achieve ZCS operation of secondary side diodes due to discontinuous resonant current. And it is also possible to control the converter in narrow frequency range and to obtain high voltage gain, which, in turn, offers low turns ratio for the transformer and high efficiency. Based on the theoretical analysis and simulation results, the 3.15W prototype is built and the final experimental results are described.