• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1767_1768
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• 2009

4-step 알고리즘을 이용하여 3차원 이미지 위상 정보를 분석하였다. Carre(1966)에 의하여 제시된 위상 분석 기술은 위상이동에 대하여 설명하고 있다. Wyant(1982)에 의한 4-step 알고리즘은 수많은 PSI(Phase-Shift Interferometry)법[1] 중에서 가장 일반적인 내용이다. 그러나 실험장비 설치 시, 매우 어렵다는 단점이 있다. 실험 과정에서 물체의 3차원 형상을 얻기 위해 매우 간단히 실험 설치를 하였다. 간섭 패턴은 추가적인 렌즈, 거울, 모터와 같은 광학장비 없이 랩뷰 프로그램과 비젼 시스템을 사용하여 구축하였다. 4-step method와 컴퓨터 프로그램에 의해 생성된 unwrapping image에 의해 물체의 wrapped된 이미지를 얻었다. 실험에 의하여 얻어진 간섭패턴을 분석 함으로써, 웨이브 프론트, 강도 그래프, 3차원 형상, 상수 데이터와 같은 다양한 정보를 얻을 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.564-574
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• 1996

This paper describes as Electronic Speckle Pattern Interferometry system which has been designed for measuring vibration patterns and quantitative measurement of vibration amplitude fields by using the time average method on a object. Visbility of fringe patterns is more improved by using the phase stepping and frame average method to reduce speckle and electric noise. And a bias vibration is introduced into the reference beam to shift the $\frac{2}{0}$ fringes so that fringe shift algorithms can be used to determine vibration amplitude. The experimental results are compared to those of the FFT analyzer and the FEM model analysis.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1529-1536
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• 2017

A digital dual-channel interleaved phase-shift full-bridge converter is investigated in this paper, and its topology and principle are analyzed. To realize current sharing and stabilize the output voltage, a controller with current sharing loop and closed voltage loop is employed. In addition, current sharing will increase the output current fluctuation and a new digital interleaved driving technology is proposed to reduce the output current ripple. To verify the analysis, simulation and experiments are carried out, which shows the effectiveness of the proposed control strategies.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.618-621
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• 1999

With the advent of the high-speed microprocessor and DSP, the possibility of executing a control strategy in digital domain has become a reality. By the use of the DSP and microprocessor controller, many high power drive system may be enhanced resulting in the improved robustness to EMI, the ability to communicate the operating conditions and the ease of adjusting the control parameters. But, the digital controller using DSP or microprocessor is not applied in the high frequency switching power supplies, especially full bridge DC/DC converter. So, this paper presents the method and realization of designing a digital-to-phase shift PWM circuit for full digital controlled full bridge DC/DC converter with zero voltage switching. The operating principles, simulation and experimental results will be presented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.255-258
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• 2008

In this paper, the battery charging device using DMFC(Direct Methanol Fuel Cell) for electric bicycle is proposed. In the proposed system, phase-shift full-bridge converter is used as a battery charger by boosting the 12V DMFC output voltage up to 36V. By using the phase-shift technique, the ringing of the transformer is reduced and the efficiency of the converter can be improved. The operation modes of proposed phase-shift full-bridge converter is analyzed and verified by the simulation and the experimental results.

• Journal of Communications and Networks
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• v.16 no.6
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• pp.583-591
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• 2014

In wireless communications, knowledge of the signal-to-noise ratio is required in diverse communication applications. In this paper, we derive the variance of the maximum likelihood estimator in the data-aided and non-data-aided schemes for determining the optimal shrinkage factor. The shrinkage factor is usually the constant that is multiplied by the unbiased estimate and it increases the bias slightly while considerably decreasing the variance so that the overall mean squared error decreases. The closed-form biased estimators for binary-phase-shift-keying and quadrature phase-shift-keying systems are then obtained. Simulation results show that the mean squared error of the proposed method is lower than that of the maximum likelihood method for low and moderate signal-to-noise ratio conditions.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1057-1058
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• 2006

In this paper, the proposed power supply is based on a modified version of the zero-voltage switching(ZVS) full-bridge phase-shift DC-DC converter, which incorporates commutation auxiliary inductors to provide ZVS for the entire load range as well as a commutation aid circuit to clamp the output diode voltage. The control strategy is based on two control loops operating in cascade mode. The complete operating principles and simulation results in presented.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.366-371
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• 2012

In this paper, we propose an electric circuit using one common-arm of H-Bridge inverters to reduce the number of switching components in the multi-level inverter combined with H-Bridge inverters and transformers. And furthermore, we suggested a new multi-level PWM inverter using PWM level to reduce THD (Total Harmonic Distortion). We use a phase-shift switching method that has the same rate of usage at each transformer. Also, we test the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of the control signal for the proposed multi-level PWM inverter.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.286-288
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• 2005

Conventional phase shift full bridge (PSFB) converter has serious voltage oscillation problem across the secondary rectifier diodes, which would require the dissipate snubber circuit, thus degrades the overall efficiency. To overcome this problem, a new voltage oscillation reduction technique (VORT) which effectively reduce the voltage oscillation of the secondary rectifier diodes for phase shift 1011 bridge converter is proposed. Therefore, no dissipate snubber for rectifier diodes is needed. In addition, since it has wide zero voltage switching (ZVS) range, high efficiency can be achieved. Operational principle, analysis of voltage oscillation, and design consideration are presented compare with that of the conventional PSFB converter. To confirm the validity of the proposed VORT, experimental results from a 420W, 385Vdc/210Vdc prototype are presented.

• Journal of Power Electronics
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• v.16 no.3
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• pp.915-924
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• 2016

A digital self-sustained phase shift modulation (DSSPSM) strategy that allows for good soft switching and dynamic response performance in the presence of step variations is presented in this paper. The working principle, soft switching characteristics, and voltage gain formulae of a LLC converter with DSSPSM have been provided separately. Furthermore, the method for realizing DSSPSM is proposed. Specifically, some key components of the proposed DSSPSM are carefully investigated, including a parameter variation analysis, the start-up process, and the zero-crossing capture of the resonant current. The simulation and experiment results verify the feasibility of the proposed control method. It is observed that the zero voltage switching of the switches and the zero current switching of the rectifier diodes can be easily realized in presence of step load variations.