• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.1208-1210
• /
• 2004

The Cold-Cathode Fluorescent Lamps (CCFL) are widely used to illuminate the liquid crystal displays(LCD) used in many battery powered instrument. This paper presents analysis of fly-back converter for universal-line applications($90\sim265Vac$) and half-bridge type resonant inverter for CCFL drive for stable characteristic and life improvement of fluorescent lamp operation frequency is higher than resonant frequency for safe operation. The validity of this study was confirmed from the simulation and experiential result.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.15 no.1
• /
• pp.18-25
• /
• 2007

The safety should be primarily considered for air vehicle, such as helicopter, which is not easy to cope with when out of order or loss of control that followed catastrophe. The U.S National Transportation Safety Board (NTSB) investigated and analyzed for 34 years rotorcraft accidents that occurred from 1963 through 1997. This paper handles intensively the relative investigation and analysis of recent 10 years domestic civil helicopter accidents to those of the United States in order to increase the safety of helicopter transportation and to consider the main design parameter before we develop Korean Civil Helicopter. To understand the overview of civil turbine helicopter accident, it uses the NTSB's accident investigation results and the overall accident trend for U.S civil single and twin turbine engine helicopter according to category, cause, activity, and phase of operation.

• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.221-223
• /
• 2000

This paper describes the design of SVC fuzzy logic controller (SVC-FLC) using adaptive evolutionary algorithm and we tuned the gain of input-output variables of SYC-FLC using it. We performed the nonlinear simulation on an single-machine infinite system to prove the efficiency of the proposed method. The proposed SYC-FLC showed the better performance than PD controller in terms of the settling time and damping effect, for system operation condition used in evaluating the robustness and three phase grounding default in cases of nominal loading used in tuning SVC-FLC for a single-machine infinite system.

• Journal of Fisheries and Marine Sciences Education
• /
• v.9 no.2
• /
• pp.209-221
• /
• 1997

This paper presents a soft switching unity power factor PWM rectifier, which features reduced conduction losses and soft switching with no auxiliary switches. The soft switching are achieved by using a simple commutation circuit with no auxiliary switches, and reduced conduction loses are achieved by employing a single converter, instead of a typical front end diode rectifier followed by a boost rectifier. Furthermore, thanks to good features such as simple PWM control at constant frequency, low switch stress and low VAR rating of commutation circuits, it is suitable for high power applications. The principle of operation is explained in detail, and major characteristics analysis and experimental results of the new converter also included.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.80-82
• /
• 1995

This paper describes a computer model of the secondary arc associated with single pole switching scheme to use in system simulation studies. The computer model is based on the mathematical model described by A.T.Johns, et.al[3], and is implemented by the EMTDC which is similar to the Electro Magnetic Transient Program(EMTP). Simulation results using the computer model compare with a previous simulation and field test results.

• Proceedings of the KIPE Conference
• /
• 1998.07a
• /
• pp.260-264
• /
• 1998

Three phase Boost/Buck converter which have economical merits and simple control scheme, are analyzed and evaluated through comparative methods and digital simulation for equivalent load. Those play a part of voltage boost/buck as well as power factor correction with single switch. Controller operating in constant and variable frequency is used for rapid output response and stable system condition respectively. Moreover low THD property of single switched converters is available for inverter arc welding machine known as high power and low power factor. So, in this paper a comparison of the characteristics in boost and buck converter is described and then simulation results conforms the merits from point of view of power factor and voltage regulator.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.05a
• /
• pp.187-192
• /
• 1999

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and its's high sensitivity. Especially when projecting a grid pattern over the object, the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, the projection moire are compared with the PMP mathematically, and it is shown that PMP can generate moire image with simple mathematical computations. Experimental works are also carried out showing the same results. It is shown that using a single gird pattern, moire image can be obtained directly without any mathematical operation when some conditions are satisfied.

• Journal of Power Electronics
• /
• v.12 no.5
• /
• pp.723-730
• /
• 2012

This paper presents a new ZVS single phase bridgeless (Power Factor Correction) PFC, using an active clamp to achieve zero-voltage-switching for all main switches and diodes. Since the presented PFC uses a bridgeless rectifier, most of the time, only two semiconductor components are in the main current path, instead of three in conventional single-switch configurations. This property significantly reduces the conduction losses,. Moreover, zero voltage switching removes switching loss of all main switches and diodes. Also, auxiliary switch turns on zero current condition. The presented converter needs just a simple non-isolated gate drive circuitry to drive all switches. The eight stages of each switching period and the design considerations and a control strategy are explained. Finally, the converter operation is verified by simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.3
• /
• pp.180-191
• /
• 2022

In this paper, a single-stage alternating current (AC)-DC converter is proposed for the automated-guided vehicle wireless charging system. The proposed converter is capable of soft-switching under all input voltage (VAC: 220 Vrms ± 10%), load conditions (0-1 kW), and air gap changes (40-60 mm) by phase control at a fixed switching frequency. In addition, controlling a wide output voltage (Vo: 39~54 VDC) is possible by varying the link voltage and improving the input power factor and the total harmonic distortion factor. Experimental results were verified by making a prototype of a 1-kW wireless power charging system that operates with robustness to changes in air gaps.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.2B no.3
• /
• pp.115-124
• /
• 2002

This paper presents an active auxiliary edge-resonant DC link snubber with a ringing surge damper and a three-phase voltage source type zero voltage soft-switching inverter with the resonat snubber treated here for the AC servo motor driver applications. The operation of the active auxiliary edge-resonant DC link snubber circuit with PWM voltage is described, together with the practical design method to select its circuit parameters. The three-phase voltage source type soft-switching inverter with a single edge-resonant DC link snubber treated here is evaluated and discussed for the small-scale permanent magnet (PM) type-AC servo motor driver from an experimental point of view. In addition to these, the AC motor stator current and its motor speed response for the proposed three-phase soft-switching inverter employing Intelligent Power Module(IPM) based on IGBTS are compared with those of the conventional three-phase hard-switching inverter using IPM. The practical effectiveness of the three-phase soft-switching inverter-fed permanent magnet type AC motor speed tracking servo driver is proven on the basis of the common mode current in a novel type three-phase soft-switching inverter-fed AC motor side and the conductive noise on the mains terminal interface voltage as compared with those of the conventional three-phase hard-switching inverter-fed permanent magnet type AC servo motor driver for the speed tracking applications.