• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.9
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• pp.931-935
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• 2003

A multilayer two-stage LC bandpass filter using low-temperature cofired-ceramic(LTCC) is proposed in this paper. The proposed bandpass filter is composed of two ceramic substrates with different dielectric constant instead of single ceramic material from top to bottom layer. Inductive elements are designed in a low permitivity ceramic layer to reduce parasitic effects and loss, while capacitive elements are designed in a high permitivity ceramic layer for size reduction. The proposed filter has 950 MHz center &equency, 118 MHz tractional bandwidth, and 3.5 dB insertion loss. And, the total size of this filter is 2.5${\times}$2.5${\times}$l.4mm$^3$. The performance of filter is analyzed by changing coupling capacitance between each resonator.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.3
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• pp.80-85
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• 2008

Capsule endoscopes generally use primary cells as a power source due to its limited space. However, the primary cells have several limitations such as high cost, limited power and no reuse. To solve these problems, a new wireless energy transmission method is proposed. The proposed approach uses air-gap transformer concepts and LC resonance to transmit energy from transmitter(primary side) to capsule endoscopes(secondary side). The ferrite core with 3-axis winding is used to increase energy transfer efficiency regardless of direction and location. The experimental results show that the proposed method stably supplies 30mW power to secondary circuit.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.445-450
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• 2012

We have developed an implantable wireless sensor for real time pressure monitoring of blood circulation system. MEMS (micro-electro-mechanical system) technology was adopted as a sensor development method. The sensor is composed of photolithographically patterned inductors and a distributed capacitor in gap between the inductors. A resulting LC resonant system produces its resonant frequency in range of 269 to 284 MHz at 740 mmHg. To read the resonant frequency changed by blood pressure variation, we developed a custom readout system based on a network analyzer functionality. The bench-top testing of the pressure sensors showed good mechanical and electrical functionality. A sensor was implanted into tibial artery of farm pig, and interrogated wirelessly with accurate readings of blood pressure. After 45 days, the sensor's electrical response and histopathology were studied with good frequency reading and biocompatibility.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.6
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• pp.24-30
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• 2009

We compared 3 kinds of ignitor characteristics and represented the procedure in order to turn the HID lamp on. Also, we analysed the cable characteristic based on the length between ignitor and the HID lamp and proved it theoretically. In practice, the ignition voltage contains a lot of problems because it is easily changed by the structure of ignitors, cable length and characteristics. In this paper, therefore, 3 ignitors, which are LC resonant typed, arc-gap circuit typed and drive frequency variable typed, have simulated and analysed with the 25[m] cable length. After careful consideration of comparisons made of all the ignitors' and cables' characteristics, a number of possible solutions were finalized.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.478-484
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• 2004

In this paper, two lossless snubber cells are proposed to generalize high frequency converter with losslless snubber. The selecting of snubber cells, which generalize high frequency converters, are depended on converter topologies. The cells have a saturable inductor, LC resonant tank and two diodes. In the cells, the saturable inductors extremely reduce resonant energy in the LC resonant tank. By minimizing resonant energy, the converter, which applies snubber cells, can operate at high frequency. These cells are applied for Buck, Boost, Buck-Boost, Cuk, ZETA, and SEPIC to generalize converter which have lossless snubber. The boost type converter has been implemented, with 400 kHz switching frequency for 125 W load to verify the converter characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.3
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• pp.171-176
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• 2013

In this paper, we present a MEMS (micro-electro-mechanical system) implantable blood pressure sensor which has designed and fabricated with consideration of size, design flexibility, and wireless detection. Mechanical and electrical characterizations of the sensor were obtained by mathematical analysis and computer aided simulation. The sensor is composed of two coils and a air gap capacitor formed by separation of the coils. Therefore, the sensor produces its resonant frequency which is changed by external pressure variation. This frequency movement is detected by inductive coupling between the sensor and an external antenna coil. Theoretically analyzed resonant frequency of the sensor under 760 mmHg was calculated to 269.556 MHz. Fused silica was selected as sensor material with consideration of chemical and electrical reaction of human body to the material. $2mm{\times}5mm{\times}0.5mm$ pressure sensors fitted to radial artery were fabricated on the substrates by consecutive microfabrication processes: sputtering, etching, photolithography, direct bonding and laser welding. Resonant frequencies of the fabricated sensors were in the range of 269~284 MHz under 760 mmHg pressure.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.261-262
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• 2011

본 논문은 LCL-필터를 사용하는 대용량 풍력 발전 시스템의 간단한 능동 댐핑 알고리즘을 제안한다. L-필터, LC-필터와 비교해볼 때, LCL-필터는 비교적으로 작은 인덕터 값을 이용하여 계통 전류의 고주파를 제거할 수 있지만, 공진이 발생된다. 따라서 LCL-필터 사용 시 공진보상은 필수적이다. 본 논문에서는 추가적인 센서나 수동소자의 사용 없이 개선된 DFT 알고리즘을 이용하여 능동댐핑을 수행하는 방법을 제한했고, 시뮬레이션을 통해서 성능을 입증한다.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.184-187
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• 2008

본 논문에서는 유도가열방식을 이용한 과열증기 발생장치를 제안하였다. 발열방식은 외부의 가열코일로부터 특수 합금 발열체에 비접촉 상태로 전자유도 와전류를 구조체에 흐르게 하였다. 인버터는 스위칭주파수 20[kHz]대역에서 작동되는 풀-브릿지 고주파 직렬 부하 공진형이며, LC 공진 설계에서 부하자체를 L로 선정하여 효율을 최대화 하였다. 개발된 장치는 전자유도가열 발열체와 유체이동에 의한 새로운 열교환 방식으로 일체의 연소과정 없이 기체, 액체 및 증발체 등을 상온에서 500[$^{\circ}C$]이상의 고온에 이르기까지 고정도의 가열이 가능하여 작업환경 개선이 가능하다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.151-152
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• 2015

산업용으로 사용되는 전기흡착식 오일 플러싱 시스템에 코로나 방전층을 형성하기 위해서 10kV이상의 고전압원이 필요하다. 현재 전기흡착식 오일 플러싱 시스템을 위한 고전압원으로 고전압 변압기와 다이오드 정류 방식을 사용되고 있으나 변압기 구동을 저주파로 구동하므로 시스템의 크기 줄이는데 제약이 있다. 이러한 무게와 부피를 저감하기위한 다른 방식으로는 고주파의 하프 브릿지 컨버터와 2차단의 전압 더블러 방식을 채택하는데 이 방식의 경우 앞단의 스파이크성 전류로 인하여 다이오드의 발열 문제가 심각하다. 이러한 문제점을 해결하기 위해서 LC 공진형 컨버터를 제안하였으며 컨버터의 설계 또한 제시하였다. 이러한 설계와 제안된 컨버터의 효용성을 검증하기 위해서 최대 출력 150W와 출력전압 15kV의 시작품을 제작하여 실험을 실행하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.488-495
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• 2009

This paper proposes a new AC/DC RPPB(Resonant Piezo-Powered Boost) converter for energy harvesting using a piezoelectric device which converts mechanical vibration energy to electrical energy. The AC/DC RPPB converter can operate with only the harvested energy without an additional power conversion circuit for switching circuit and transfer energy to a load of which the voltage is higher than piezoelectric voltage. With the review of published topologies of the converter for energy harvesting, the operation principle of the AC/DC RPPB converter, and the results of PSPICE simulation and experiment are presented to prove the feasibility of the new converter for the energy harvesting.