• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1149-1150
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• 2007

In this paper, operation of isolated current-fed full-bridge converter with active clamp is investigated by simulation and experiments. Experimental waveforms show a good agreement with the corresponding simulation results. Further, losses such as conduction loss, turn-on/off loss of MOSFETs and diodes are measured and their characteristics in the converter is addressed. 200W prototype DC-DC converter is developed for verification of the derived operating modes, design rules and loss analysis.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1560-1561
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• 2007

Electrodeless fluorescent lamp exhibit two modes of operation : a low density mode in which the power is capacitively coupled to the plasma and which is known as the E-mode, and a higher density mode which is an inductive discharge known as the H-mode. The transition between these two(E to H) mode exhibits hysteresis. It is observed that transition currents change at different frequencies and hysteresis exists not only between the starting and minimum maintaining currents of the electromagnetic mode (H mode) discharge but also between the starting and minimum maintaining currents of the electrostatic mode (E mode) discharge. Hysteresis effect can be important role in dimming system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.11
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• pp.930-937
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• 2012

Newly developed Series hybrid low-floor articulated vehicle which can meet both road and railway running conditions. It has the rated driving speed of 80 km/h and three driving modes with hybrid(engine+battery) driving mode, engine driving mode, battery driving mode. The battery driving mode requires the several 10 km running without additional charging operation. The vehicle has been equipped with LPB (lithium polymer battery) pack for the series hybrid propulsion system. LPB pack consists of 168 cells (3.7 V in a cell, 80 Ah) in series, DC Circuit breaker, mechanical rack, BMS (battery management system). This paper has shown the design process of LPB pack and application to the vehicle. Driving results in the road was successful to be satisfied with the requirement of the series hybrid vehicle.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.78-82
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• 2004

This paper suggests the power system reliability evaluation fur transmission lines planning in composite power systems. In recent the importance and necessity of some studies on reliability evaluation of grid comes from the recent black-out accidents occurred in the world. Since probabilistic criterion can reflect recognize the probabilistic nature of system components, the application of probabilistic criterion has received a lot of attention. This paper introduces features and operation modes of the Transmission Reliability Evaluation fur Large-Scale Systems(TRELSS) Version 6.2, a program made in EPRI, for assessing reliability indices of composite power system. The characteristics of the TRELSS program are illustrated by the case studies using the KEPCO system.

• Journal of the Korean Society of Visualization
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• v.6 no.1
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• pp.27-33
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• 2008

Air flow inside an automotive HVAC module has been investigated using a high-resolution PIV technique with varying the temperature operation mode. The PIV system consists of a 2-head Nd:YAG laser (125 mJ), a high-resolution CCD camera (2K$\times$2K), optics and a synchronizer. A real automotive HVAC module was used directly under real operating condition. Some casing parts of the HVAC module were replaced with transparent windows for capturing clear flow images with laser light sheet beam illumination. Time-averaged velocity fields were obtained for two different temperature control modes. Flow characteristics of the air-conditioned air flow inside the automotive HVAC system for the two temperature baffle conditions were evaluated.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.41-47
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• 2011

With the world-wide demand on the emission minimization, the needs on the diesel aftertreatment devices with high efficiency are also increasing. In order to effectively develop or design a high-performance diesel particulate filter, a clear understanding on the deposition and regeneration mechanism is required. In the present study, a theory on the lumped parameter model for wall-flow type diesel particulate filters is described focusing on the deposition efficiency, pressure drop inside the filter. The fourth order explicit Runge-Kutta method is utilized for the mass flow rate computation. Engine operation modes with controlled and uncontrolled regeneration options are selected. The computational lumped parameter model is validated by comparing the computed results with the measured data.

• Journal of Power Electronics
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• v.18 no.6
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• pp.1619-1626
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• 2018

The output power of most facilities for renewable energy generation is unstable due to external environmental conditions. In distributed power systems with two or more sources, a stable output can be achieved with the complementary power supply among the different input sources. In this paper, a double-input DC-DC converter with a wide-input-voltage-range is proposed for renewable energy generation. This converter has the following advantages: the circuit is simple, and the input voltage range is wide and the fault tolerance is excellent. The operation modes and the steady-state analysis are examined. Finally, experimental results are illustrated to verify the correctness of the analysis and the feasibility of the proposed converter.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1750-1759
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• 2018

A complete code-package for gyrotron simulation to analyze its performance is under development in UNIST, Korea. We first time report the present status of the code-package named as UNIST Gyrotron Design Tool (UGDT). It can perform design simulations for gyrotron's interaction cavity, RF window, and the essential mode calculations including the study of mode competition. We will discuss about its salient features, theory, numerical implementation, and its calculation result for 95 GHz UNIST Gyrotron. Moreover, we will validate its capability to perform the mode competition calculation for fundamental and second harmonic modes.

• Journal of IKEEE
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• v.22 no.4
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• pp.1088-1092
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• 2018

In this paper, we propose a dual-mode frequency tripler using push-push and stacked FET structures. The proposed circuit can operate either in frequency multiplier mode or in amplifier mode. In the frequency multiplier mode, push-push frequency multiplication is achieved by allowing input signals with particular phase shifts. In the amplifier mode, the device operates as a distributed amplifier to obtain high gain. Also both modes were designed using stacked FET structure. The designed circuit showed frequency tripled output power of 9.7 dBm at 2.4 GHz with the input at 800 MHz. On the other hand, in the amplifier mode, the device showed 8.9 dB of gain to generate 19.5 dBm at 800 MHz.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.327-333
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• 2019

This study analyzes the reverse recovery phenomenon of a semi-bridgeless rectifier (SBR) in an inductive power transfer (IPT) system for electric vehicles. Ideally, the reverse recovery phenomenon does not occur in a diode rectifier, however, in practical systems, the reverse recovery phenomenon occurs even when the SBR operates like a diode rectifier due to high operating frequency. Therefore, a practical analysis of operation modes for SBRs is presented in this study, considering the reverse recovery phenomenon, and the requirements for SBR switches are proposed. The analysis results are experimentally verified using a 3.3 [kW] IPT system prototype to which three different types of switches are applied.