• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.157-162
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• 2000

The electro-optical characteristics of TN(twisted nematic)-LCD(liquid crystal display) with photo-dimerized on a PMCh(poly(4'methacryoyloxylchalcone)) surface using a new photo-dimerization method was studied. The excellent voltage-transmittance(V-T) curve of TN-LCD with photo-dimerized on a PNCh surface for 1 min. using a new photo-dimerization method was observed. Also, the voltage-hold-ing-ratio(VHR) of TN-LCD with photo-dimerized on a PMCh surface using a new photo-dimerization method is higher than that of conventional photo-dimerization method. Consequently, we suggest that the new photo-dimerization method. Consequently, we suggest that the new photo-dimerization method for LC aligning is the most promising rubbing-free techniques.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.365-367
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• 2000

Recently, the power supply equipments have tendency to take multiple feedback loop paths. In this paper, the state space averaging technique is applied for the analysis of flyback type current mode control circuit. We made real converter for the gurantee of stable output characteristic and proper design of feedback circuit. The validity of proposed method is verified from test results. The improvement of stability is confirmed by sinusoidal signal injection method with isolated transformer. It is known that phase margin is sufficient and gain crossover frequency $f_c$ is nearly 1/5 of switching frequency $f_s$ from the experimental result with frequency response analyzer.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.378-380
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• 2000

According to the rapid growth of high speed and precise industry the application of synchronous motor has been increased. In the application fields, the fast dynamic response is of prime importance. In particular, since the PMSM has characteristics of high speed, high thrust, it has used in high-performance servo drive. From these reasons, it is recently used for high precise position control, and machine tool. In this paper, using the state observer, robust vector position control method for the purpose of improving the system performance deterioration caused by parameter variations is proposed.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.247-249
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• 2000

Transient phenomena cause delay in control response and must be studied and eliminated, if possible, suppressed. The difficulty in analyzing transient phenomena in ac machines comes from the large number of windings involved. But, it is possible that only one phase is used to represent three phases of the induction motor as called phase segregation method. The phase segregation method provides equivalent circuits for both the steady and transient states of induction motor. In this paper, analysis of the torque transient of the induction motor be carried out the phase segregation method and confirmed in the possibility of transientless torque control.

• School Mathematics
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• v.2 no.1
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• pp.111-144
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• 2000

The purpose of this study is to develop instruction sequence and teaching units for secondary school geometry using dynamic computer software like CabriII, GSP, Wingeom, Poly. For this purpose, literature was reviewed on various issues of geometry education and geometry curriculum using dynamic software. By the literature review, instructional sequence for teaching geometry in middle schools was designed. And, based on the newly developed instructional sequence, one sample teaching unit was developed. The basic principles for the development were to connect intuition geometry and formal geometry, and to emphasize students' investigative experience. Finally, experiment to check out teachers' response to the newly developed material was conducted by using questionnaire.

• Journal of Biosystems Engineering
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• v.25 no.5
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• pp.359-368
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• 2000

In this paper, mathematical model was developed for predicting the tractive performance of off-road wheeled vehicles operated on soft terrains. Based on the mathematical model, a computer simulation program(TPPMWV) was developed. The model takes into account main design parameters of wheeled vehicle, including radius and width of front and rear tire, weight of vehicle, wheelbase and driving type(4WD, 2WD). Soil characteristics, such as the peressure-sinkage and shearing characteristics and the response to repetitive loading and slip-sinkage effect, are also taken into consideration. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMWV with measured ones obtained by field tests for two different driving types of wheeled vehicle. As a results, the drawbar pulls predicted by the TPPMWV were well matched to the measured ones within the absolute errors of 3.916%(4WD) and 13.31%(2WD) for two different driving types, respectively.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.28-35
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• 2010

This paper presents new Adaptive Linear Combination Structure (ADALINE) for tracking/estimating voltage-current phasor and frequency of power system. To estimate the phasors and frequency from sampled data, the algorithm assumes that orthogonal coefficients and speed of angular frequency of power system are unknown parameters. With adequate sampled data, the estimation problem can be considered as a linear weighted least squares (LMS) problem. In addition to determining the phasors (orthogonal coefficients), the procedure estimates the power system frequency. The main algorithm is verified through a computer simulation and data from field. The proposed algorithm is tested with transient and dynamic behaviors during power swing, a step change of frequency upon islanding of small generators and disconnection of load. The algorithm shows a very high accuracy, robustness, fast response time and adaptive performance over a wide range of frequency, from 10 to 2000 Hz.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.96-101
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• 2000

The effects of internal fluid motion have to be considered in the analysis of liquid storage containers. Therefore this thesis developed a three-dimensional boundary element-finite element method for the analysis of rectangular liquid storage containers. The irrotational motion of inviscid and incompressible ideal fluid is modeled by using boundary elements and the motion of structure by finite elements. Coupling is performed by using compatibility and equilibrium conditions along the interface. Dynamic response characteristics of rectangular liquid storage containers such as sloshing motion, hydrodynamic pressure, displacement by fluid-structure interaction are investigated.

• Journal of the Korean Society of Safety
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• v.15 no.3
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• pp.45-51
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• 2000

This paper studies the effect of vibrational characteristics of the various tubes analyzed though experiment. By an experiment analysis we found out that the factor of system vibration is fluid-structure interaction of tube line. In fluid-filled tube system we study on the influence that the natural frequency of system and the frequency of wave motion produce upon through three experiments. Three experiments are modal test on each tube, FRF in continuous system, and vibrating tests when the system is driving on. From the results of the experimental studies, we obtained that the natural frequencies of system are very important than wave induced vibrations. and according to the variation of configuration, the frequencies are different each other. And we found that though fluid passed away through the tube, the tendency of system vibration level was similar with the mode shape at the simple system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.1
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• pp.77-83
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• 2000

구조물의 동특성은 대형구조물을 상시감시 할 수 있는 장점으로 인하여 널리 활용된다. 상시감시를 위해 계측된 랜덤 데이터는 FFT를 통한 구조물의 동적 고유특성을 분석함으로써 이루어진다. 이 과정에서 Input Data와 Response Data사이에서 FFT Analyzer를 통하여 FRF가 측정된다. 특히 랜덤 데이터의 계측은 여건과 환경에 따라 발생하는 Noise로부터 가능한 정확한 FRF를 계측해야만 성공적인 구조물의 고유의 동적특성을 파악하게 된다. 랜덤 데이터에서 발생할 가능성이 높은 입력, 출력 Noise를 동시에 최소화 할 수 있는 새로운 개념의 FRF측정 알고리즘을 제안한다. 이 알고리즘에 의하여 장대형 모형교량으로부터 Modal 실험을 수행하여 계측된 동특성을 FE 해석 결과와 비교 평가하여 유용성을 제시한다.