• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1484-1489
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• 2005

An inhomogeneous and anisotropic rock has different properties at different location. Thus, this refers to any of the properties which we may be measuring. There are two concepts of rock mass, namely, CHILE(Continuous, Homogeneous, Isotropic, Linear Elastic) material and DIANE(Discontinuous, Inhomogeneous, Anisotropic, Non-linear Elastic) rock. The former is essentially the properties of intact rock, the latter is essentially the properties governed by the structure of rock. In geotechnical aspect, the most important parameter is strength of rock or rock mass. In particular, characteristics of strength of rock mass depend upon the orientation of discontinuities And this orientation of discontinuities has different properties at different direction of excavation. Therefore, it needs for characterization of different properties of discontinuity orientation against different direction of excavation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2240-2246
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• 2007

Optically coupled linear isolation amplifier requires special care to avoid oscillation in actual applications. In this paper methods to analyze the frequency characteristics of the amplifier are proposed to reveal the cause of oscillation and to provide design guidelines. The loop gain of the amplifier obtained through the equivalent circuit model shows that the phase margin is too small to ensure stable operations. Methods to get non-oscillatory response are proposed and the resulting frequency responses are analyzed. The common method adding a small capacitor to the amplifier is shown to degrade the frequency bandwidth. The frequency response of output voltage explains the need of filter capacitor in output stage. The usefulness of the method is verified through experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.41-53
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• 1994

In this paper, rotating-bending fatigue tests of the SiC-whisker- reinforced 6061-T6 aluminum alloy and 6061-T6 alumiunm alloy made by power metallurgy were carried out to investigate the fatigue characteristics of plain and notched specimens at room temperature. The fatigue mechnisms in both materials were clarified through successive surface observations using the plastic replica method. In the case of the SiC-whisker-reinforced composites, there are whisker rich and poor zones and the fatigue crack is nucleated from the end of whiskers near the boundary. On the other hand, in the case of the 6061-T6 aluminum alloy, the fatigue crack is nucleated from defects and propagates by shear. Moreover, the results were discussed based on linear notch mechanics.

• International Journal of Aeronautical and Space Sciences
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• v.2 no.2
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• pp.56-64
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• 2001

An optical temperature sensor based on the etched planar waveguide Bragg grating is developed and its performance is explored using theoretical and experimental methods. The planar waveguide is designed and fabricated using optical lithography and wet chemical etching. An efficient butt coupled optical fiber is used to examine the spectral characteristics of the grating sensor, and to investigate the grating parameters. The typical bandwidth and reflectivity of the surface etched grating has been ~0.2 nm and ~7%, respectively, at a wavelength of ~1,552 nm. The temperature-induced wavelength change of the optical sensor is found to be slightly non-linear over ${\sim}200^{\circ}C$ temperature range. Theoretical models for the grating response of the sensor based on waveguide and classical laminated plate deformation theories agree with experiments to within acceptable tolerance.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.276-279
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• 2005

The proposed Novel OverDriving Technology with Optimum Look-up-Table（LUT）is suggested to be a better solution to reducing the occurrence of overshooting caused by the traditional overdriving method implemented to normally liquid crystal (VA mode). Chunghwa Picture Tubes, LTD. (CPT) has successfully implement this tech into 20 inch TFTLCD TV module at the present day. The proposed technology can speed up gray-to-gray response time of LCD less than one half of frame time. On the side, Optimum LUT construction apply the compression scheme to record total actual grayscale transfer characteristics instead of applying the normal spread method such as linear / non-linear interpolation. The memory space is been reduced and the distortion of the image quality is lesser.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2345-2354
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• 1998

There have been many researches to yield higher resolution image quality from the low resolution CCD device. The resolution of it is primary factor for the image quality of digital still camera and in manufacturing price. IN this paper, image enlargement algorithm, which reduces blocking effect of enlarged low resolution image and minimizes ringing and blur effect occurring around edge in linear interpolation, is proposed. This algorithm is composed of gaussian low pass filter which eliminates aliasing, least square spline interpolation and non-linear interpolation based on step edge model.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.67-72
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• 2005

In the grade change operations inputs and outputs are highly correlated and application of conventional linear feedback control methods such as PID schemes might lead to poor control performance. In this study the neural networks model for the grade change operation is trained by using bilinear terms which can represent non-linear characteristics of grade change operations. The inverse model of the grade change operation is obtained from training and the optimal input variables are computed from the trained neural networks as well. The proposed bilinear inverse model predictive control scheme was found out to showlittle discrepancy between simulated outputs and setpoints.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.4
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• pp.57-67
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• 1996

This paper aims to support delay-sensitive multimedia applications by suggesting a mechanism in which maintains almost constant end-to-end delay thus providing the optimum playout synchronization. For this task the sum of network delay and buffering delay is entiredly managed and to eliminate little delay fluctuations and instantaneous delays at a buffer and a network, a low pass filter is used. Furthermore the correction function, which is used for maintaining the buffering level ot a reference value, is a non-linear step function, unlike the existing linear and continuous function. it has a different step sizes adapting to a traffic characteristics of a network congestion. the proposed mechanism has been confirmed of it sefficiency through SLAM-II netowrk.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.659-663
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• 2002

The brake systems of high-speed train are to be equipped with three different brake systems, such as regenerative brake with regenerative feedback in driving car, a pneumatic disc brake, and non-contact linear eddy-current brake(ECB). The regenerative brake and the pneumatic disc brake are acting on the wheels. Their achievable braking force depends on the adhesive coefficient, which is influenced by the weather condition and speed, between the wheel and The linear eddy current brake gets an economical solution in the high-speed train because of the independence of the adhesive coefficient, no maintenance needed. and the good control characteristics. The braking force and the normal force of ECB for korean high-speed train are analysed by the 2D FEM(Finite Element Method). Finally the normal force is compared with the experiential values to verify the analysis.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.23-25
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• 2009

전력용 커패시터는 전압 보상 및 부하에 필요한 무효전력을 전원측을 대신하여 공급함으로서 역률을 향상시킬 수 있으며, 리액터와 직렬로 연결할 경우 비선형 부하에서 발생하는 고조파 성분을 흡수하여 전압 고조파 왜형을 줄이고 전류고조파를 흡수하는 필터로도 사용이 가능하다. 그러나 수용가 부하가 일정하지 않고 변동하거나 선형부하와 비선형 부하가 존재할 경우 커패시터가 고조파의 홉수 등으로 인해 고장이 나는 경우가 많은 편이다. 그래서 본 연구에서는 현장에서 각 부하기기에 고조파를 줄이는 장치의 부착과 부착 전후 커패시터에 미치는 영향을 측정 분석하여 커패시터 규정과의 비교도 실시하였다.