• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.2030-2032
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• 1998

It is always necessary to high performance power supplies for the magnet system in the accelerator, especially when the number of power supplies are large. When have developed the compact power supply using switching technology instead of SCR phase control. We adopt the pulse width modulation(PWM) method with a half bridge DC/DC converter. In this way, we can make a compact system with light weight and small volume. Actual system we developed is 1.2kW, 35V/35A bipolar DC power supply current precision of +/-0.02%. It is possible to mount 10 unit in a conventional 19 rack. The built in controller has an RS422 protocol to drive 10 unit by one serial port up to 1.2km distance. If we adopt RS485 protocol, one serial port can control 32 power supplies. In this paper, we will report the design and performance of the prototype power supply.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.978-981
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• 2005

The vibration analysis of damped sandwich beam is conducted using finite element method. The equation of motion presented by Mead and Markus is used to formulate FEM. Also as the thickness of the core in the damped sandwich beam goes to zero, conventional beam theory based on the transformed-section method and the equation of Mead and Markus are compared. According to the change of thickness and loss factor of the core, the forced frequency response of beam is calculated and discussed. And then using the half-power band width method, the damping ratio of each mode is calculated and discussed about each case.

• 전력전자학회논문지
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• 제12권5호
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• pp.364-371
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• 2007

본 논문은 단상하프브릿지 구조를 갖는 계통연계형 전압형 PWM 인버터를 위한 필터설계를 목적으로 한다. 단상하프브릿지 전압형 PWM 인버터의 교류출력단 전압과 계통전압의 관계를 분석하여 필터 인덕터에 순시적으로 인가되는 전압의 특징적인 관계를 정성적 및 정량적으로 파악하였다. 또한 교류출력단 전압의 분석을 기초로 하여 필터인덕터에 흐르는 스위칭리플전류의 크기를 정량적으로 구하였다. 이러한 분석을 기초로 하여 계통주입전류의 기본파성분에 대한 스위칭리플전류의 비율을 평가함수로 하는 필터인덕터의 설계법을 제시하였다. 제안된 설계방법을 시뮬레이션 및 실험을 통하여 검증한다.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.13-19
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• 2019

This paper proposes a systematic method for estimating detection performances of a frequency-modulated continuous wave radar using electromagnetic simulations. The proposed systematic method includes a radar system simulator that can obtain range-Doppler images using the electromagnetic (EM) simulations in conjunction with a test setup employed for performance evaluation of multiple targets at different velocities in a traffic environment. This method is then applied for optimizing the half-power beamwidths of the antenna array using an evaluation metric defined to improve the detection strengths for the multiple targets. The optimized antenna has vertical and horizontal half-power beam widths of $10^{\circ}$ and $60^{\circ}$, respectively. The results confirm that that the proposed systematic method is suitable to improve the radar detection performance with the enhanced radar-Doppler images.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.59-69
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• 2012

There are two types of inverters that are generally used in induction heating systems: voltage type inverters and high-frequency half-bridge inverters. This paper proposes a new resonant inverter for induction heating systems using the current type full-bridge method. The proposed method can remove capacitors at the input end, and enables unity power factor operation by preventing phase differences of voltage and current. Furthermore, Zero Voltage Switching (ZVS) which is in tune with current type inverter can be adopted and continuous power adjustment is possible through duty ratio changes and frequency modulation in switching operation. Simulations and experiments showed that the proposed current type full-bridge resonant inverter could be used for unity power factor control and ZVS operation in induction heating systems.

• Journal of Power Electronics
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• 제19권1호
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• pp.34-43
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• 2019

An improved half-bridge LLC converter with a magamp auxiliary post-regulator is proposed in this paper. The function of the magamp is bypassed when the converter works within the low input-voltage range. Meanwhile, it operates as an auxiliary post-regulator when the input voltage is high. By changing the blocking time of the magamp, the dc gain of the converter can be extended. Hence, the input voltage range of the converter is extended. The realization of proposed topology does not require a complicated circuit. The controller of the magamp can be easily implemented using only passive components, transistors and an OP amp. The generalized operational principle is analyzed and the design criterion for the magamp is presented. Finally, a 25V output, 400W experimental prototype was built and tested for a 160-300V input-voltage range to verify the feasibility of the proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.193-195
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• 2007

This paper proposed a novel current measurement method for two-phase half-bridge inverter using single current sensor. The proposed method measures DC link input current and a phase current simultaneously and reconstructs each phase currents by simple calculation according to voltage vector. The commutation modes of two-phase half-bridge inverter is analized. The current sampling and reconstructing method is also presented. The proposed method is verified through simulation and experimental results on two-phase induction motor drive system.

• 한국전산구조공학회논문집
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• 제20권2호
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• pp.127-136
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• 2007

본 논문에서는 비동질 반무한 평면에 대한 비례경계유한요소법의 식을 유도하고 수치예제를 해석하였다. 비례경계유한 요소법은 편미분 방정식을 경계방향으로는 유한요소와 같은 근사를 통해서 약화시키고 방사방향으로는 정확해를 사용하는 반 해석적인 방법으로, 방사방향으로 멱함수를 따라 탄성계수가 변화되는 반무한 평면에 대해서 관계식을 가상일의 원리에 근거하여 새로이 유도하였다. 이 과정에서 반무한평면의 거동이 Euler-Cauchy방정식을 따름을 보이고, 기존의 동질 반무한평면의 해석시 도입되던 로그모드가 비동질 반무한 평면의 해석에는 유효하지 않음을 보였다. 수치예제를 통하여 유도된 식이 타당한 거동을 보임을 증명하고 이 접근법이 실제 공학적 문제의 해결에 있어서 유용함을 보였다.

• 전력전자학회논문지
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• 제22권5호
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• pp.423-430
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• 2017

This paper proposes a control methodology for a high efficiency operation of an inductive power transfer (IPT) converter by combining full bridge (FB) and half bridge (HB) controls. To apply the proposed control to the IPT converter, the characteristics of each control method are analyzed. By examining the output voltages of the IPT converter and a theoretical loss analysis, the control shifting points between FB and HB controls are evaluated in accordance with the coupling coefficients and the load. Based on the control shifting points, the FB-HB control algorithm is implemented. By applying FB-HB control, high efficiency operation at the light load condition can be achieved.

• 전력전자학회논문지
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• 제22권3호
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• pp.256-262
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• 2017

This paper presents the control algorithm of a single-phase AC/DC/AC PWM converter for the linear compressor of a refrigerator. The AC/DC/AC converter consists of a full-bridge PWM converter for the control of the input power factor and a half-bridge PWM inverter for the control of the single-phase linear compressor. At the DC-link of this topology, two capacitors are connected in series. These DC-link voltages must be balanced for safe operation. Thus, a new control method of DC voltage balancing for the half-bridge PWM inverter is proposed. The balancing algorithm uses the Integral-Proportional controller and inserts the DC-offset current at the Proportional-Resonant current controller of the inverter to solve the DC-link unbalanced voltages between the two capacitors. The proposed algorithm can be easily implemented without much computation and additional hardware circuit. The usefulness of the proposed algorithm is verified through several experiments.