• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.7
• /
• pp.337-345
• /
• 2006

This paper proposes a high speed SRM drive system for blower application with a new 4-level inverter and precise excitation position generator. For a high speed blower, a proper inverter and control method are proposed and the output characteristics are analyzed. In order to get a fast build-up and demagnetization of excitation current, a 4-level inverter system is proposed. The proposed 4-level inverter has additional charge capacitor, power switch and diode in the conventional asymmetric converter. The charged high voltage is supplied to the phase winding for fast current build-up, and demagnetization current is charged to additional capacitor of the 4-level inverter. In addition, a precise excitation position generator can reduce turn-on and turn-off angle error according to sampling period of digital control system. The proposed high speed SRM drive system is verified by computer simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.2
• /
• pp.83-88
• /
• 1999

Series connection of power semiconductor devices is selected in high voltage and high power applications. It is important to prevent the overvoltage from being induced across a device above ratings by the proper voltage balancing in the field of IGBT series connection. In addition, the overvoltage induced by a stray inductance has to be limited in the high power circuit. This paper proposes a new gate control scheme which can balance the voltage properly and limit the overshoot by controlling the slope of collector voltage under the turn-off transient in the series connected IGBTs. The proposed gate control scheme changes the slope of collector voltage by sensing the collector voltage and controlling the gate signal actively. The new series connected IGBT gate driver is made and its validity is verified by the experimental results for series connected IGBT circuit.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1807-1809
• /
• 2002

In this study, asolid-state laser system adopting a firing time control(FTC) method in which three flashlamps are turned on consecutively was designed and fabricated to examine the pulse width and the pulse shape of the laser beams depending upon the changes in the lamp turn-on time. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on three flashlamps consecutively on a real-time basis with the aid of a PIC one-chip microprocessor With this technique, the lamp turn-on delay time can be varied more diversely from 0 to 10 ms and the real-time control is possible with an external keyboard enabling various pulse shapes. In addition longer pulses can be more widely used for industrial processing and lots of medical purposes.

• Proceedings of the KIEE Conference
• /
• 2002.07c
• /
• pp.1846-1849
• /
• 2002

A shorted-turn test was performed at the Sininchon combined cycle power plant on gas turbine generators. The test was conducted using a permanent flux probe and on-line diagnosis system. The flux probe installed in the generator air gap senses the field winding slot leakage flux and produces a voltage proportional to the rate of change of the flux. This pattern of flux variation is a signature unique to each field winding. We have also applied a voltage waveform analysis technique that can identify the pole location, slot number and number of shorted-turn with each slot.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.2
• /
• pp.67-73
• /
• 2010

In this study, a camber angle generating mechanism for rear suspension is suggested. An experimental device is implemented and tested. A full vehicle model with camber angle generating device by using ADAMS/Car is modeled. Rear left wheel and rear right wheel have 5 different camber angles in the simulations, respectively. Step steer and pulse steer simulations are carried out for investigating the effects of vehicle handling performance due to camber angle control of rear suspension. According to the results, the camber angle of rear suspension affects the vehicle handling performance during both simulations. Therefore, when the vehicle makes the right turn or left turn, left and right wheel should have the proper orientation for improving the handling performance, respectively.

• International Journal of Aeronautical and Space Sciences
• /
• v.2 no.1
• /
• pp.93-102
• /
• 2001

Flight control design for the autonomous waypoint navigation of aircraft is presented in this study. The waypoints are defined in terms of desired longitude and latitude. The control design is conducted in longitudinal and lateral directions, respectively. The lateral control is based upon coordinated turn strategy for which no sideslip is allowed under the turning maneuver. The longitudinal control is mainly focused on altitude hold during navigation. Neural network control approach is applied to the altitude-hold mode control. Simulation of the proposed control strategy has been performed under various conditions. A graphical simulation tool was developed to visually demonstrate the control technique developed in this study. A method to simulate the gas turbine transient behavior is developed. The basic principles of the method.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
• /
• 1998.11a
• /
• pp.88-93
• /
• 1998

The purpose of this study was to examine theory about indoor thermal comfort-environment as well as to determine thermal sensation and physical responses for men in summer and winter indoor environment, under various air temperature and relative humidity, with male university students. Subjective Evaluation, Heart rate(Electrocardiogram, ECG), Electroencephalo gram(EEG) were examined. We found that comfort of people was achieved at SET*. 24.7$^{\circ}C$, -0.82${\alpha}$-wave) both in summer and in winter.

• Journal of Welding and Joining
• /
• v.6 no.2
• /
• pp.40-46
• /
• 1988

The effect of heat input on the content of residual .delta.-ferrite and the hot cracking susceptibility in the austenitic stainless steel overlaid on the carbon steel was studied in the range of heat input from 7.5 to 15.1 KJ/cm. Present study shows that residual .delta.-ferrite content in the overlay is mainly determined by the dilution of the base metal (carbon steel) which is in turn affected by heat input, i.e. the amount of dilution decreases as heat input increase. Accordingly, higher heat input results in a substantial increase in Cr equivalent but a little increase in Ni equivalent due to the less dilution of carbon from base metal. This fact can explain the result obtained in this study, i, e, the higher content of .delta.-ferrite in the weld deposit made with higher heat input. This in turn causes more resistant overlaying weld metal to hot cracking.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.6
• /
• pp.23-29
• /
• 2011

In this study, a camber angle generating mechanism for front and rear suspension is suggested. An experimental device is implemented and tested. A full vehicle model with camber angle generating device by using ADAMS/Car is modeled. Step steer simulations are carried out for investigating the effects of vehicle handling performance due to camber angle change of front and rear wheel. According to results, the camber angle of rear suspension affects the vehicle handling performance during both simulations. Therefore, when the vehicle makes the right turn or left turn, left and right wheel of front and rear suspension should have the proper orientation for improving the handling performance, respectively.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2010.04a
• /
• pp.363-365
• /
• 2010

In this study, based on numerical map GIS-T Dataset build and by using ArcGIS Network Analysis emergency vehicle's reach time were analyzed. AutoCad using 1: 50,000 based on roads and hospitals of numerical map were creating a Polyline and Point and Network Dataset made using ArcCatalog. ArcGIS Analysis setting the interval for the period reached 3 minutes, 5 minutes, 15 minutes was set and then U-Turn was set to not allow because U-turn takes a long time to calculate and does not happen often on the real road. Intersection of the passage of time, considering that the emergency vehicles were set to 3 seconds. To expand by taking advantage of this facility on Vulnerable area will be used as base material. If we focus on analyzing the emergency activity to convert little data, To prepare for disaster and disaster will be able to use the materials.