• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.246-248
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• 2002

This paper presents a high-frequency voltage source inverter for silent corona discharge ozonizer application, which is characterized by the power control based on pulse density modulation (PDM). The PDM inverter produces either a square -wave ac-voltage state or a zero-voltage state at its ac terminals to control the average output voltage under constant do voltage and operating frequency. This results in a wide range of power control in the silent corona discharge load with a strong nonlinear characteristics. And proposed addition circuit for maintain discharge on the center of the airgap. In this paper, schemed equivalent electric circuit of the discharge electrode for simulation. Finally, the effectiveness of this discharge tube character of silent corona ozonizer is investigated in the simulation results.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.89-92
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• 2001

Silent gas discharge method has been widely applied for ozone production, ultraviolet light and UV laser generation. Since ozone and ultraviolet applications have tendency to spread widely in industry, the development of efficient and low-cost power supply for such systems is a task of great impotency. This paper introduces high-frequency inverter type mode power supply designed for ozone generation tube and ultraviolet generation excimer lamp and considerations on this inverter and pulse density modulation control strategy applied in it.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.26-29
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• 1999

Superconducting $YBa_{2}$$Cu_{3}$ $O_{7-x}$(YBCO) thin films were deposited on MgO(100) substrates using a hollow cathode discharge sputtering system. Influence of the sputtering conditions such as substrate temperature and discharge sputtering gas pressure on electrical and structural properties were investigated. It was found that YBCO thin films with zero resistance temperature higher than 85 K were obtained to the pressure 200 mToorr(Ar/O2=0.9), substrate temperature of $760^{\circ}C$, and target-substrate distance of 10 mm during film deposition. Homogeneous large area YBCO films with 2 inch diameter were also sucessfully fabricated by this method.

• Journal of Power Electronics
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• v.2 no.3
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• pp.206-211
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• 2002

Silent gas discharge method has been widely applied fur ozone production, ultraviolet light and UV laser generation. Since ozone and ultraviolet applications have tendency to spread widely in industry, the development of efficient and low - cost power supply for such systems is an important task at present. This paper introduces high-frequency inverter type mode power supply designed fur ozone generation tube and ultraviolet generation excimer lamp and considerations on the design of the inverter and pulse density modulation control strategy applied in it.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.527-528
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• 2012

DBD (Dielectric Barrier Discharge) plasma actuator was designed for aerodynamic drag reduction using plasma flow control, and the drag reduction was measured by wind-tunnel tests using 2D test model. At the zero wind velocity, the plasma flow control had no effect on the drag reduction because the flow separation and surface friction drag were not occurred. At the wind velocity of 2m/s, 9.7% of drag was reduced by the flow separation control. The drag reduction decreased as the wind velocity increased.

• Journal of Power Electronics
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• v.4 no.1
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• pp.39-45
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• 2004

A novel current-fed energy-recovery sustaining driver (CFERSD) for a PDP is proposed in this paper. Its main idea is to recover the energy stored in the PDP or to inject the input source energy to the PDP by using the current source built-up in the energy recovery inductor. This method provides zero-voltage-switching (ZVS) of all main power switches, the reduction of EMI, and more improved operational voltage margins with the aid of the discharge current compensation. In addition, since the current flowing through the energy recovery inductor can compensate the plasma discharge current flowing through the conducting power switches, the current stress through all main power switches can be considerably reduced. Furthermore, it features a low conduction loss and fast transient time. Operations, features and design considerations are presented and verified experimentally on a 1020${\times}$l06mm sized PDP, 50kHz-switching frequency, and sustaining voltage 140V based prototype.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.376-379
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• 2005

High efficiency and low cost sustain driver for plasma display panel (PDP) with current fed is proposed. Main concept of the proposed circuit is using the current source to charge and discharge panel. As a result, all power switches can achieve the zero voltage switching (ZVS) and every auxiliary switch can also do the zero current switching (ZCS). Moreover, since the inductor current can compensate the discharge current, the current stress of all power switches can be reduced considerably. Furthermore, it has features as a simpler structure, less mass, less cost, and lower electromagnetic interference than prior circuit.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.286-291
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• 2015

LLC resonant converter is used to control laser output power in Nd:YAG laser. Zero voltage switching (ZVS) is implemented to minimize the switching loss which is adopting the LLC resonant converter. In the spot welding processing of metal thin films, the processing quality is decided by the laser beam output energy of single pulse. We decide to the 50 [J] as the single pulse laser beam energy. Laser output power is investigated and experimented by changing the output current. That current is controled by the charging voltage of capacitor. From those results, we obtained the maximum laser output of 58.2 [J] and the conversion efficiency of 2.52% at the discharge voltage of 620V and the discharge current of 861 [A] and the pulse repetition rate of 1 [Hz] at the charging capacitor of 12,000 [${\mu}F$].

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.250-257
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• 2023

Tree in river have environmental functions such as ecosystem preservation and flood control functions that protect the riverbank. On the other hand, excessive tree development can have the negative effect of fixing the sand bar and reducing the cross-sectional area. Nays2D simulation results performing two flow conditions (average dam operation discharge and two-year frequency discharge) and four tree density conditions (current, zero, low, high tree density) used as input data for PHABSIM to calculate WUA (Weighted Usable Area). The results show that riverbed changes occur more significantly in the zero tree density than presence of trees, which could have a positive impact on the biological habitat environment of Zacco platypus.

• Journal of Korea Water Resources Association
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• v.38 no.4 s.153
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• pp.271-280
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• 2005

The goal of this study is to recommend a new type of stage-discharge rating curve ($Q=p(h-e)^{\beta}-{\gamma}$) useful for satisfying divergence, and one other seemingly irresolvable problem related to exited rating curves, while also extending this rating curve model. The problem of divergence is that during the finding of the CZF (cease-to-zero flow) parameter e and while minimizing the sum of total errors of the estimated curve, the exponential parameter ${\beta}$ become an abnormally large value. The insoluble problem is that when the value e is greater then the recorded minimum at the gauged stage, it is impossible to have a negative logarithm value (h-e). The two problems above can be satisfied by adapting the control value ${\gamma}$, which affects the reduction of ${\gamma}$ and gives us the possibility of controlling (h-e) over zero. The study results show that the effects of parameter ${\gamma}$ are very similar to that of e when conducting physical and sensitivity analyses. This system can be used towards developing a new stage-discharge rating curve for river discharge, for use in evaluating the acceptability of existing stage-discharge rating curves generated by using hydrologic analyses at all stations.