• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.364-365
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• 2004

• Bulletin of the Society of Naval Architects of Korea
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• v.18 no.2
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• pp.35-40
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• 1981

• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.379-383
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• 1998

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.277-282
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• 2005

This paper describes a step-down AC voltage regulator using an AC chopper and auxiliary transformer, which is a series connected to the main input. The detail design of the AC regulator, logic and PWM pattern of the AC chopper is described and the three-phase AC regulator using two single­phase AC choppers with a three transformer configuration is proposed for three-phase application. The proposed three-phase system has the advantages of lower system cost due to reduced switch number and gate driver circuit as well as advantages of decreased size and weight because it uses a series compensated scheme. The proposed AC regulator has many benefits such as fast voltage control, high efficiency and simple control logic. Experimental results indicate that it can be used as a step-down AC voltage regulator for power saving purposes very efficiently.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.197-202
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• 2004

Recent researches have shown that IKONOS Geo imagery is capable of pixel-level geopositioning accuracy. However, a large number of ground control points(GCPs) are required in this case. For reducing the number of GCPs, users try to use the vender-supplied RPCs with Geo imagery. But, the biases included in RPCs give rise to absolute positioning error of about 25m as well known. In this paper, a method for the compensation of biases in rational polynomial coefficients(RPCs) for IKONOS Geo imagery is developed. the method requires provision of one or two GCPs to generate the compensated RPCs, and the analysis result of practical testing represents two or three pixels accuracy from IKONOS Geo imagery in case of using only compensated RPCs without GCPs.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1205-1208
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• 1995

The optically-gated p-i-n diode switches have been fabricated with gold-compensated silicon. The turn-on and turn-off delay times and the rise and fall times were measured as a function of optical power level, bias, and pulse width. The turn-on characteristics shows a strong dependence an optical pulse power and a delay time(${\delta}{\iota}$) between two pulses, but a weak dependence on the width of optical pulse. Actually there is no turn-off delay in gold-doped p-i-n switches and the fall time is negligible.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.188-188
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• 2009

We have studied the optically compensated splay (OCS) mode using reactive mesogen (RM) monomer to reduce critical voltage, setting voltage and phase transition time from initial bend to splay state. Through the polymerization of UV curable RM monomer, the high pretilt angle from vertical alignment was formed at the surfaces. In this way, orientation of the LC with OCS mode can be achieved without setting voltage and improved electric characteristic.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.975-980
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• 2004

Positioning system is widely used for many practical applications. This system requires a good controller to achieve high accuracy and fast response with simple and self-adjustable design. In order to satisfy the above requirements, a new practical controller for positioning systems, namely nominal characteristic trajectory following (NCTF) controller with PI compensator, has been proposed. However, the effect of actuator saturation can not be completely compensated for integrator windup when the object parameters vary. This paper presents a method to improve the NCTF controller by overcoming the problem of integrator windup by adopting a fuzzy system. The improvement of the NCTF controller is evaluated through simulation using a rotary positioning system. The simulation result has demonstrated the effectiveness of the compensated NCTF in overcoming the problem of integrator windup.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.74-77
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• 2002

In this paper we present a novel temperature compensated Hall effect power IC for accurate operation of wide temperature and high current drive of the motor coil. In order to compensate the temperature dependence of Hall sensitivity with negative temperature coefficient(TC), the differential amplifier has the gain consisted of epi-layer resistor with positive TC. The material of Hall device and epi-resistor is epi-layer with the same mobility. The variation of Hall sensitivity is -38% at 150$^{\circ}C$ and 88% at - 40$^{\circ}C$. But the operating point(B$\sub$op/) and release point(B$\sub$RP/) of the Hall power IC are within ${\pm}$25%. The experimental results show very stable and accurate performance over wide temperature range of -40$^{\circ}C$ to 125$^{\circ}C$.

• Journal of the Korea Society of Computer and Information
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• v.23 no.8
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• pp.17-23
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• 2018

In this paper, we implemented a flight posture simulator that intuitively understands aircraft flight posture and visualizes the principle of motion. The proposed system operates the 6 - axis motion platform according to the change of the navigation information and transmits the flight attitude to the simulator using the gyro sensor. A gyro sensor and an acceleration sensor are used together to analyze the attitude of the aircraft. The reason is that the gyro sensor has a cumulative error in the integration process. And the accelerometer sensor was compensated by using the complementary filter because noise was serious due to short term vibration. Using the compensated sensor information, the motion platform is operated by calculating the angle to be transmitted to the 6-axis motor. And visualization result is implemented using OpenGL. The results of this study can be used as teaching materials for students related to aviation in the future.