• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2000년도 학술대회논문집
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• pp.70-76
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• 2000

In the charge system, a contact type-convenient-charging method is insufficient because of the contact failure around moist environment and troublesome question to put in and pull out. For the solution of this problem, an electromagnetically coupled non-contact charger for the rechargeable cell is proposed using ZVS multi-resonant forward converter with synchronous rectifier. In this paper coupling coefficient(k), leaking inductance, coupling inductance and resonant frequency are observed for the air gap. By using the observed value, this circuit is designed and implemented. This proposed circuit is simulated by the PSPICE and experimented. The stress of a main switch and the output power are measured.

• 전력전자학회논문지
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• 제17권2호
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• pp.142-149
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• 2012

The independently regulated dual-output LLC resonant converter using only one power stage and one control IC is proposed in this paper. The conventional dual-output LLC resonant converter requires the extra non-isolated DC/DC converter to obtain the tightly regulated slave output voltage, which results in the low power conversion efficiency and high production costs. On the other hand, since the proposed converter controls the master and slave output voltages by pulse width modulation(PWM) and pulse frequency modulation(PFM), it can achieve tightly regulated dual output voltages without the additional non-isolated DC/DC converter. Therefore, it features a high efficiency and low cost. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a 40W LED driver prototype are presented.

• 전력전자학회논문지
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• 제22권5호
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• pp.463-468
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• 2017

One of the most critical part for magnetron driving in microwave oven is start-up control. For this, switching frequency of resonant inverter should be carefully controlled in order to supply sufficient power to the filament of the magnetron and to prevent rectifier diode from destruction caused by the excessive voltage across them. This paper proposes a novel start-up control strategy for LLC resonant inverter for microwave oven considering the non-oscillation mode time and the magnetron voltage during the start-up process. The validity of the proposed method is verified through the experiment with 1,200W microwave oven using LLC resonant inverter.

• Structural Engineering and Mechanics
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• 제32권6호
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• pp.725-740
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• 2009

A new simple relation for the estimation of modal correlation coefficients is presented. It is obtained from the decomposition of covariances of modal responses into background and resonant contributions, as it is commonly done for the variances. Thanks to appropriate assumptions, the modal correlation coefficients are estimated as weighted sums of two limit values, corresponding to the background and resonant responses respectively. The weighting coefficients are expressed as functions of the background-to-resonant ratios, which makes the proposed formulation convenient and easily accessible. The simplicity of the mathematical formulation facilitates the physical interpretation. It is for example proved that modal correlation coefficients can be non negligable even in case of well separated natural frequencies, which is sometimes unclear in the litterature. The new relation is mainly efficient in case of large finite element models. It is applied and validated on a finite element buffeting analysis of the Viaduct of Millau, the highest bridge deck ever built so far.

• 한국전자파학회논문지
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• 제22권1호
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• pp.106-113
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• 2011

본 논문에서는 구형 도파관의 협벽에 이중 슬롯을 가진 비공진형 슬롯 도파관 안테나를 설계하였다. 설계된 협벽 슬롯 도파관 안테나는 슬롯의 기울임 각도에 의해 복사되는 에너지가 결정되기 때문에, 요구되는 부엽 크기를 만족시키는 복사에너지의 크기 분포가 나오도록 각 슬롯의 기울임 각도를 조정하였다. 기울임 각도의 조정은 기존의 슬롯 도파관 안테나의 설계에서 주로 사용되는 슬롯 컨덕턴스 추출 방법이 아닌, 개개의 슬롯 개구면 필드를 푸리에 변환하여 원전계 복사 패턴을 계산하고, 원전계 복사 패턴으로부터 최대 크기의 분포를 산출하는 방법을 사용하였다. 제안된 방법으로 비공진형 이중 슬롯 도파관 안테나를 설계하고, 실제 제작하여 안테나 성능을 측정, 비교하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.52-55
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• 2000

In this paper, the coupled and the non-coupled vibration mode AE sensor for GIS were simulated by finite element analysis and manufactured, and characterized. The maximum sensitivity was 64.3 dB when the resonant frequency of the coupled vibration mode AE sensor was 166 kHz and the maximum sensitivity was 58.9 dB when the resonant frequency of the non-coupled mode AE sensor was 265 kHz. The coupled vibration mode AE sensor responded higher than the non-coupled vibration mode AE sensor at the partial discharge detection in GIS.

• 한국정밀공학회지
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• 제25권11호
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• pp.90-94
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• 2008

Recently, a great deal of research is focused on the printed electronics. One of their mainly concerned products is printed RFID tag. RFID technology has attracted researchers and enterprises as a promising method for automatic identification, and they are expected to replace conventional bar codes in inventory tracking and management. The key to successful RFID technology lies in developing low-cost RFID tags and the first step in applying printing technology to RFID systems is to replace antennas that are conventionally produced by etching copper or aluminum. However, due to the printing quality variations, errors, and lower conductivity, the performance of the printed RFID antennas is lower than that of antennas manufactured by conventional etching methods. In this paper, the effect of variations in the printing conditions on the antenna performance is investigated. Three levels for each condition parameter is assumed and effect on the resonant frequency are examined experimentally based on orthogonal array. The most serious factor that affects the resonant frequency of the antenna is the non-uniformity of the edge and the resonant frequency is found to be lower as the non-uniformity increases.

• Advances in Computational Design
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• 제2권4호
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• pp.283-291
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• 2017

High frequency full bridge series resonant inverters have become increasingly popular among power supply designers. One of the most important parameter for a High Frequency Full Bridge Series Resonant Inverter is optimal coil design. The optimal coil designing procedure is not a easy task. This paper deals with the New Approach to Optimal Design Procedure for a Real-time High Frequency Full Bridge Series Resonant Inverter in Induction Heating Equipment devices. A new design to experimental modelling of the physical properties and a practical power input simulation process for the non-sinusoidal input waveform is accepted. The design sensitivity analysis with Levenberg-Marquardt technique is used for the optimal design process. The proposed technique is applied to an Induction Heating Equipment devices model and the result is verified by real-time experiment. The main advantages of this design technique is to achieve more accurate temperature control with a huge amount of power saving.

• 대한기계학회논문집B
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• 제23권6호
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• pp.795-801
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• 1999

An experimental investigation has been conducted with the objective of studying the mixing mechanism near the nozzle exit in a tone-excited jet diffusion flame. The fuel jet was pulsed by means of a loudspeaker-driven cavity. The excitation frequencies were chosen for the two cases of the non-resonant and resonant frequency identified as a fuel tube resonance due to acoustic excitation. The effect of tone-excitations on mixing pattern near the nozzle exit and flame was visualized using various techniques, including schlieren photograph and laser light scattering photograph from $TiO_2$ seed particles. In order to clarify the details of the flame feature observed by visualization methods, hotwire measurements have been made. Excitation at the resonant frequency makes strong mixing near the nozzle. In this case, the fuel jet flow in the vicinity of nozzle exit breaks up into disturbed fuel parcels. This phenomena affects greatly the combustion characteristics of the tone excited jet and presumably occurs by flow separation from the wall inside the fuel nozzle. As a result, in the resonant frequency the flame length reduces greatly.

• Journal of Power Electronics
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• 제13권3호
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• pp.329-338
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• 2013

In this paper, the charging characteristics of series resonant type high voltage capacitor chargers considering the transformer stray capacitance have been studied. The principles of operation for the four operational modes and the mode changes for the four different switching frequency sections are explained and analyzed in the range of switching frequency below the resonant frequency. It is confirmed that the average charging currents derived from the above analysis results have non-linear characteristics in each of the four modes. The resonant current, resonant voltage, charging current, and charging time of this capacitor charger as variations of the switching frequency, series parallel capacitance ratio ($k=C_p/C_s$), and output voltage are calculated. From the calculation results, the advantages and disadvantages arising from the parallel connection of this stray capacitance are described. Some methods to minimize charging time of this capacitor charger are suggested. In addition, the results of a comparative test using two transformers whose stray capacitances are different are described. A 1.8 kJ/s prototype capacitor charger is assembled with a TI28335 DSP controller and a 40 kJ, 7 kV capacitor. The analysis results are verified by the experiment.