• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.279-282
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• 2000

As digital systems continue to use components with faster edge rates and clock speeds, transmission of the digital information in these systems approaches the microwave realm. At these speeds digital signal fidelity becomes both a critical success factor and design challenge. The noise sources in digital systems include the noise in power supply, ground and packaging media due to simultaneous switching of drivers, signal reflections and distortions on single and multiple transmission lines. This paper presents theory, case studies and design considerations of gigabit interconnection for network and communication systems. The case studies show HSPICE and Ampredictor simulations of alternate approaches. Various subjects including skin effect and dielectric losses, interconnect simulations and crosstalks of connector, affected signal discontinuity, are addressed.

• 전자공학회논문지B
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• 제33B권6호
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• pp.164-175
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• 1996

In this thesis, to cope with severe intersymbol interference and nonlinear distotions of the digital magnetic recording channel a neural decision feedback equalizer (NDFE) and an adaptive neural equalizer (NE) are applied. The digital magnetic recording channels with various recording densities and different types of the nonlinear distortions are considered. The computer simulation shows that as the nonlinear distortion is increased, the neural equalizers (NdFE, NE) have advantages of approximately 2-4 dB in signal to noise ratio (SNR) over the onventional eualizers to reach sme bit error rate and, a sthe recording density is increased, 1~5 dB of SNR improvement are also gained. Especially the NdFE gives a superior performance over the other equalizers when there is a severe nonlinear distortion in the digital magnetic channel.

• 소성∙가공
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• 제5권3호
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• pp.219-231
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• 1996

The current five-stage cold extrusion process to produce an axle-housing is investigated for the purpose of improved process. The main goal of this study is to obtain an appropriate reduced process sequence which can produce the required part most economically without tensile crack-ing workpiece buckling and overloading of the tools. The current process sequence is simulated and design criteria are examined. during the simulation several remeshings are done due to severe mesh distortions, Based on the results of simulations of the current five-stage process, design strategy for improving the process sequence are developed using the thick hollow pipes. The finished product of an axle-housing is produced in two operations and one annealing treatment while the conventional sequence consists of five operations and one annealing treat-ment. Also die loads of the new process are compared with those of the current one.

• 대한기계학회논문집
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• 제17권5호
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• pp.1095-1105
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• 1993

본 연구에서는 앞서 개발된 3차원 강소성 유한요소법을 이용하여 H-형강 압연 공정을 해석하여 그 타당성을 검토하고 이를 실제의 공정 설계에 이용할 수 있도록 하였다.

• 한국전기전자재료학회논문지
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• 제15권6호
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• pp.529-534
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• 2002

Recently, As the higher frequency in clock of digital system being demanded and the density of circuits gets high for purpose of making light and minimizing system, the study for solution of digital signal distortion being interested. In this paper, the distortion of square pulse caused by dispersion as it propagates along a single microstrip line and crosstalk between lines on the Multi-Transmission Lines (MTL) is investigated. The dispersion and crosstalk of pulse signals is analyzed regarding to the structure of transmission line such as relative permittivity, substrate height, strip width of the microstrip line and pulse width of signal pulse.

• 한국자기공명학회논문지
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• 제1권2호
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• pp.63-70
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• 1997

The conformation of the self-complementary decamer duplex, d(ACGTATACGT)2 (TATA-duplex) has been studied by proton NMR spectroscopy. The duplex is essentially B-type, with distortions apparent at the TATA steps. These conformational distortion which may be preferable to occur in the thymine residue on the 5'-side, has been investigated by unusual NOE crosspeaks.

• 한국자기공명학회논문지
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• 제4권1호
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• pp.64-73
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• 2000

There are several methods to achieve selective NMR image of differing chemical species with the three most popular methods of Dixon's, CHESS, and SECSI. A major problem common to all chemical shift imaging methods is the uniformity of the static magnetic field and distortions introduced when RF coils are loaded with a conducting specimen. Without magnetic field shimming, these methods cannot be used to acquire selectively image protons in fat and water which are separated by approximately 3.0ppm. Experiments with a phantom, with linewidths of 2.5 to 3.5ppm, were quantitatively evaluated for the three methods and a new chemical shift imaging method. In this study the new chemical shift imaging method (modified CHESS+SECSI technique) which included a selective saturation and refocusing pulse, was developed to determine the ratios of water and fat in different samples.

• 대한조선학회논문집
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• 제44권1호
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• pp.32-39
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• 2007

A three-dimensional finite element model has been developed to simulate the MIG P/S welding process of two aluminum plates. The finite element calculations are performed using ANSYS finite element code, which takes into account the thermal and mechanical non-linear material properties. The results of finite element analysis compared with those of experiment to show its validity in view of distortions. Parametric studies are carried out on the validated model to assess the effects of various factors on the final residual distortion. Large deformations, temperature dependent material properties are included in the model. Finally, the formulas of fitting curves of angular distortion transverse shrinkage, and longitudinal shrinkage have been proposed.

• 전자공학회논문지B
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• 제30B권9호
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• pp.84-93
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• 1993

Recently, several nonlinear shape normalization methods have been proposed in order to compensate for the shape distortions in handwritten characters. In this paper, we review these nonlinear shape normalization methods from the two points of view : feature projection and feature density equalization. The former makes feature projection histogram by projecting a certain feature at each point of input image into horizontal-or vertical-axis and the latter equalizes the feature densities of input image by re-sampling the feature projection histogram. A systematic comparison of these methods has been made based on the following criteria: recognition rate, processing speed, computational complexity and measure of variation. Then, we present the result of quantitative evaluation of each method based on these criteria for a large variety of handwritten Hangul syllables.

• 전기학회논문지
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• 제56권6호
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• pp.1111-1116
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• 2007

Antennas of the near field detection radar require little distortion in time domain caused by multi reflections between feed and open ends of the antenna, so that help to discriminate the target signal from the clutters. The resistive loading techniques have been used to reduce the late time distortions in order to prevent masking of target. In this paper, we design a microstrip antenna with two arms having sloted lines, which have inductance loading effect. Implemented antenna shows better performance on reducing late-time ringing, and the peak value of the received signal becomes 45% greater than the one by the antenna with two non-sloted lines.