• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.263-269
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• 1996

A comprehensive scaling method is proposed for a scaled-down facility simulating SBLOCA in the CARR passive reactor (CP-1300). The present method consists of two stages: scaling methodology, and validation of scaling methodology and code. The present scaling methodology is based on the integral response scaling method. Through sensitivity study, the condensation of the top of the CMT is identified as one of the little-known phenomenon with high importance which should be addressed for the applicability of the code. Using the similarity of the derived scaling parameters, the major component geometries of the scaled-down facility are determined. In the case of 1/4 height and 1/100 area ratio scaling, it is found out that the power ratio is the same as the area ratio, and the present scaling methodology generates the design parameters of the scaled-down facility without any distortion.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.413-416
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• 2011

본 논문에서는 인간의 시각 인지 능력(Human Visual System; HVS)을 기반으로 하는 영상 품질 측정 방법을 제안한다. 보다 구체적으로 제안하는 시각 인지 기반의 영상 품질 측정 방법은 기존의 객관적인 품질 평가 방법인 PSNR 품질 측정 방법에 1) HVS 에 기반한 foveated contrast sensitivity 을 이용하여 집중 영역으로부터 거리에 따른 인식률 저하를 반영하였으며, 이와 동시에 2) Just Noticeable Distortion(JND)을 통해 영상의 휘도 대비 차이에서 오는 인식률 차이를 반영하여 사용자가 인지하는 품질을 계산하였다. 이러한 연구 결과는 특히 대형 영상의 부호화 과정에서 양자화 및 bit allocation, 또는 기 부호화된 영상의 전송 과정에서 차등화된 오류 보호 기술 등에 활용할 수 있을 것이다.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.116-124
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• 2011

A service robot can identify its own position relative to landmarks, the locations of which are known in advance. The main contribution of this research is that it gives various ways of making the self-localizing error smaller by referring to special landmarks which are developed as high gain reflection material and coded array associations. In this paper, the authors propose a set of indices to evaluate the accuracy of self-localizing methods using the selective reflection landmark and infrared projector, and the indices are derived from the sensitivity enhancement using 3D distortion calibration of camera. And then, the accurarcy of self-localizing a mobile robot with landmarks based on the indices is evaluated, and a rational way to minimize to reduce the computational cost of selecting the best self-localizing method. The simulation results show a high accuracy and a good performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.476-479
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• 1997

A Knowledge of friction force in pneumatic cylinders makes it possible to improve cylinder description during simulation and to asses performance under changing operating conditions more accurately. Such knowledge is particularly useful, for example, when modeling continuous pneumatic positioning systems or predicting the operating conditions under which stick slip may occur, as well as in establishing preventive maintenance procedures for pneumatic cylinders. Friction force depends on a number of factors, including operating pressure, seal running speed on the cylinder barrel and rod, barrel material and surface roughness, seal dimensions and profile, seal material, lubrication conditions, cylinder distortion during assembly, and the operating temperature of cylinder components. This paper shows a system for measuring the friction force caused by a seal used in pneumatic cylinders. Results of experimental tests show that seal friction forces for grease lubricated service are clearly dependent on speed and pressure and are les sensitivity to other parameter. i.e., barrel material and roughness, seal material, and profile.

• Journal of KSNVE
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• v.8 no.5
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• pp.887-899
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• 1998

It has been resulted that Lagrange multiplier method with statistical approach was superior to traditional harmonic balance method in identifying the nonlinear loudspeaker parameters when output signals were contaminated with Gaussian random noise. We have known that the displacement-dependent characteristic values of nonlinear parameters identified by traditional harmonic balance method were estimated less than original values by the increase of output noise and the stiffness coefficients were very sensitive to output noise. Also, by the sensitivity analysis we have verified that the harmonic distortions in acoustic radiation was mainly due to nonlinearity of force factor caused by uneven magnetic fields and that reducing the nonlinearity of damping coefficients were very effective for improving second harmonic distrotion of acoustic radiation.

• Computational Structural Engineering : An International Journal
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• v.3 no.1
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• pp.19-29
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• 2003

In the present study, finite element linear buckling analysis is performed for grid-stiffened composite plates. A hybrid element with drilling degrees of freedom is employed to reduce the effect of the sensitivity of mesh distortion and to match the degrees of freedom between skins and stiffeners. The preliminary static stress distribution is analyzed for the determination of accurate load distribution. Parametric study of grid structures is performed and three types of buckling modes are observed. The maximum limit of buckling load was found at the local skin-buckling mode. In order to maximize buckling loads, stiffened panels need to be designed to be buckled in skin-buckling mode.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1094-1098
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• 2013

AVI (Automatic Vision Inspection) systems automatically detect defect features and measure their sizes via camera vision. Defect detection is not an easy process because of noises from various sources and optical distortion. In this paper the acquired images from a TFT panel are enhanced with the adoption of an HVS (Human Visual System). A human visual system is more sensitive on the defect area than the illumination components because it has greater sensitivity to variations of intensity. In this paper we modified an MTF (Modulation Transfer Function) in the Wavelet domain and utilized the characteristics of an HVS. The proposed algorithm flattens the inner illumination components while preserving the defect information intact.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.405-408
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• 2002

LSP(Line Spectrum Pairs) Parameter is used for speech analysis in vocoders or recognizers since it has advantages of constant spectrum sensitivity. low spectrum distortion and easy linear interpolation. However the method of transforming LPC(Linear Predictive Coding) into LSP is so complex that it takes much time to compute. Among conventional methods, the real root method is considerably simpler than others, but nevertheless, it still suffers from its jndeterministic computation time because the root searching is processed sequentially in frequency region. We suggest a method of reducing the LSP transformation time using voice characteristics The proposed method is to apply search order and interval differently according to the distribution of LSP parameters. in comparison with the conventional real root method, the proposed method results in about 46.5% reduction. And, the total computation time is reduce to about 5% in the G.723.1 vocoder.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.277-280
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• 2010

LSP(Line Spectrum Pairs) Parameter is used for speech analysis in vocoders or recognizers since it has advantages of constant spectrum sensitivity, low spectrum distortion and easy linear interpolation. However the method of transforming LPC(Linear Predictive Coding) into LSP is so complex that it takes much time to compute. Among conventional methods, the real root method is considerably simpler than others, but nevertheless, it still suffers from its indeterministic computation time because the root searching is processed sequentially in frequency region. We suggest a method of reducing the LSP transformation time using voice characteristics.

• Korean Journal of Optics and Photonics
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• v.14 no.6
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• pp.588-593
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• 2003

A signal processor for interferometeric fiber optic sensors, which measure dynamic quantities of frequency up to 1 KHz with high sensitivity, is developed. It is a high-speed version of the all-digital phase tracking (ADPT) processor that was used to measure static or slowly-varying quantities. The processor was applied to a fiber optic Mach-Zehnder interferometer to evaluate the performance. The measured total harmonic distortion was near to -50 ㏈, which is the theoretical limit or the ADPT signal processing.