• 전기학회논문지
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• 제61권3호
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• pp.472-478
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• 2012

The inspection machine in PCB (printed circuit board) assembly line checks assembly errors by inspecting the images inside of the component inspection region. The component inspection region consists of region of component package and region of soldering. It is necessary to extract the regions automatically for auto-teaching system of the inspection machine. We propose an image segmentation method to extract the component inspection regions automatically from images of PCB. The acquired image is transformed to HSI color model, and then segmented by several regions by clustering method. We develop a modified K-means algorithm to increase the accuracy of extraction. The heuristics generating the initial clusters and merging the final clusters are newly proposed. The vertical and horizontal projection is also developed to distinguish the region of component package and region of soldering. The experimental results are presented to verify the usefulness of the proposed method.

• Earthquakes and Structures
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• 제13권1호
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• pp.9-15
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• 2017

In this paper, the influence of the rotational component, about a vertical axis, of earthquake ground motion on the response of building structures subjected to seismic action is considered. The torsional component of ground motion is generated from the records of translational components. Torsional component of ground motion is then, together with translational components, applied in numerical linear dynamic analysis of different reinforced concrete framed structure of three stories buildings. In total, more than 40 numerical models were created and analyzed. The obtained results show clearly the dependence of the effects of the torsional seismic component on structural system and soil properties. Thus, the current approach in seismic codes of accounting for the effects of accidental torsion due to the torsional ground motion, by shifting the center of mass, should be reevaluated.

• 한국강구조학회 논문집
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• 제13권2호
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• pp.201-210
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• 2001

본 연구에서는 편심 축력을 받는 가셋트-강관 접합부의 극한 내력을 파악하기 위하여 실험 및 유한요소해석을 수행하였다. 가셋트-강관 접합부의 내력에 영향을 주는 요소는 강관의 직경, 가셋트판 길이, 축력과 횡력의 비, 횡력에 의한 편심 등으로 이들이 주재의 좌굴내력에 미치는 영향을 정량적으로 파악하여 접합부 강도식을 제안하였다. 특히 횡력에 의한 편심이 주재에 작용할 때 이를 설계식에 반영하기 위하여 횡력을 등가의 모멘트 및 편심 축력으로 대치한 수치 모형을 제시하였다. 결과적으로 접합부의 작용하는 외력을 주주재 축력, 모멘트, 편심 축력으로 분해하고 각 외력에 대한 독립적인 극한내력을 구한후 이들의 상관 관계식을 구함으로써 접합부 극한강도식을 제시하였다.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.142-149
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• 2006

A PIV(Particle Image Velocimetry) was applied to measure in-cylinder velocity field according to inlet valve angle during intake stroke. Two engines, one is conventional DOHC 4 valve and the other is narrow valve angle, were used to compare real intake flow. The results show that the intake flow pattern of conventional engine is more complicated than that of narrow angle one in horizontal plane and the vertical component of in-cylinder flow is rapidly decayed at the end stage of intake. On the other hand, the flow pattern of narrow angle one is relatively well arranged in horizontal plane and the vertical velocity component remains so strongly that forms large-scale strong tumble. Two engines also form commonly three tumble; two are small and bellow the intake valve and one is large-scale. The center of large scale tumble moves to bottom of cylinder as the vertical velocity increases.

• Journal of Astronomy and Space Sciences
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• 제34권4호
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• pp.251-256
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• 2017

The electric coupling between the lithosphere and the ionosphere is examined. The electric field is considered as a timevarying irregular vertical Coulomb field presumably produced on the Earth's surface before an earthquake within its epicentral zone by some micro-processes in the lithosphere. It is shown that the Fourier component of this electric field with a frequency of 500 Hz and a horizontal scale-size of 100 km produces in the nighttime ionosphere of high and middle latitudes a transverse electric field with a magnitude of ~20 mV/m if the peak value of the amplitude of this Fourier component is just 30 V/m. The time-varying vertical Coulomb field with a frequency of 500 Hz penetrates from the ground into the ionosphere by a factor of ${\sim}7{\times}10^5$ more efficient than a time independent vertical electrostatic field of the same scale size. The transverse electric field with amplitude of 20 mV/m will cause perturbations in the nighttime F region electron density through heating the F region plasma resulting in a reduction of the downward plasma flux from the protonosphere and an excitation of acoustic gravity waves.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.332-335
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• 1999

The purpose of this study is to make clear that the relationship between the directional properties of late arriving sound and listener envelopment (LEV). Psycho-acoustical experiments are performed with an objective measure of inter-aural cross-correlation(IACC) in order In predict whether LEV is perceived equally in two kinds of sound fields with horizontal or vertical component of late arriving sound. It is found that LEV is affected by not horizontal component of late arriving sound but also vertical one.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.138-140
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• 2006

A new diagnosis model was constructed by combining atomic force microscopy (AFM), wavelet, and neural network. Plasma faults were characterized by filtering AFM-measured etch surface roughness with wavelet. The presented technique was evaluated with the data collected during the etching of silicon oxynitride thin film. A total of 17 etch experiments were conducted. Applying wavelet to AFM, surface roughness was detailed into vertical, horizon%at, and diagonal components. For each component, neural network recognition models were constructed and evaluated. Comparisons revealed that the vertical component-based model yielded about 30% improvement in the recognition accuracy over others. The presented technique was evaluated with the data collected during the etching of silicon oxynitride thin film. A total of 17 etch experiments were conducted

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.88-93
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• 1997

Amplication factor spectrum has been obtained and compared with standard Response Spectrum using the observed strong ground motions database. The observed ground motions from the Miramichi, Nahanni, Saguenay and New Madrid Earthquake (vertical component 19. horizontal component 36). which are estimated to represent domestic seismotectonic characteristics such as seismic source, attenuation, and site effect, are used for the analysis of amplication factor spectrum. Amplication factor has been calculated using both observed peak values and results from responses to the observed horizontal and vertical ground motions. The comparison shows that the amplication factors resultant from this study exceeds those of Standard Response Spectrum at relatively higher frequencies. The results implie that the characteristics of the seismic strong ground motion which may represent the domestic seismotectonic characteristics differs from those of Standard Response Spectrum, which are resultant from the strong ground motions observed mainly at the westem United States.

• 설비공학논문집
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• 제12권3호
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• pp.235-243
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• 2000

A theoretical model for laminar filmwise condensation along an isothermal vertical wall at constant pressure has been formulated on the basis of conservation laws and other fundamental physical principles. The model was applied to the prediction of the influences of variable thermophysical properties of liquid and vapor layers in the filmwise condensation of superheated vapor of Rl2, R134a, R142b and R152a. The dimensionless velocity component method was employed in the transformation of the governing equations and their boundary conditions, and the polynomial method was used for treating variable thermophysical properties of liquid and vapor. Physical quantities, such as the dimensionless thickness of the liquid layer, local heat transfer rate and mean heat transfer coefficient, were investigated for different values of the superheated temperature of the stagnant vapor far from the wall. It was found that the value of mean heat transfer coefficient of R134a was higher than other refrigerants for the change of the superheated temperature.

• 한국정보통신학회논문지
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• 제18권8호
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• pp.2051-2056
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• 2014

함정의 탈자결과 평가를 위한 자계신호의 분리방법에 대한 이론적 근거와 해저 면에 설치되는 사각코일로부터 발생하는 불균일한 자계가 분리결과에 미치는 영향을 측정 신호와 FEM해석을 통해 검토하였다. 측정신호는 제작된 모델함에서 발생하는 자계를 자계센서로 측정한 것이며 FEM 계산은 제작된 모델함과 동일한 형상으로 수행되었다. ILM(induced longitudinal magnetization) 신호와 IVM(induced vertical magnetization) 신호는 함정이 가지는 투자율과 지자계의 수평과 수직방향 성분에 의해 각각 발생하는 자화에 의한 것이며, PLM(permanent longitudinal magnetization) 신호와 PVM(permanent vertical magnetization) 신호는 함정의 영구자화의 수평성분과 수직성분에 의한 것임이 확인되었다. 또한 사각 코일의 수직방향의 자계는 균일한 지자계를 완전히 상쇄할 수 없어 사각코일의 면적에 가까운 크기를 가지는 함정 일수록 사각코일의 자계 불균일성의 영향을 크게 받게 됨을 알았다.