• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.479-486
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• 1997

식물 뿌리에 대한 지식은 식물-토양 사이의 관계 이해, 토양의 호율적 관리, 식물에 의한 영양분과 수분의 흡수 과정 이해, 그리고 토양 등급 지수를 만드는데 있어서 아주 중요하다 식물 뿌리에 관한 정보를 정량화하기 위하여는 뿌리를 흙으로부터 씻어내고 뿌리의 길이, 표면적, 중량과 같은 식물 뿌리의 특성을 측정하여야 한다 하지만 이렇게 뿌리를 씻어 낸 다음 뿌리의 특성을 측정하는 기존의 방법을 이용할 경우 막대한 시간과 노동력이 필요하여 뿌리에 관한 많은 양의 정보를 얻는데 큰 어려움이 있다. 이 연구에서는 식물 뿌리를 관측하는데 필요한 시간과 노동력을 줄일 수 있는 식물 뿌리 측정법을 세선 작업과 자외선 명암 증진법을 이용한 영상 정보 처리 장치를 바탕으로 하여 개발하였다. 개발된 화상 정보 처리 장치를 이용하여 옥수수 뿌리의 길이를 재었을 때 기존의 뿌리 길이 측정 방법보다 2.5 배 발리 측정할 수 있는 것으로 나타났다.

• Journal of KIISE:Software and Applications
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• v.27 no.6
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• pp.583-594
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• 2000

The thinning process which is commonly used in extracting skeletons from handwritten Hangul characters has a problem of distorting the original pattern shapes. This paper proposes a method of skeleton extraction using a shape decomposition algorithm. We decompose the character pattern into a set of near convex parts using a shape decomposition algorithm. From the shape-decomposed pattern, we detect the joint parts and extract the skeletons from the parts incident to the joint parts. Then the skeletons not incident to the joint parts are extracted. Finally, the process of skeleton extension is performed to ensure the connectivity. We setup five criteria for the comparison of quality of skeletons extracted by our method and the thinning based method. The comparison shows the superiority of our method in terms of several criteria.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.84-88
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• 2003

In this paper, The optimum design of a die shape has been carried out the FEM analysis of a pilger mill process considering various factors. The pilger mill forming process consists of a pair of rotating die which has appropriate surface shape. The important design parameters of the pilger mill are the feed rate and the profile of grooved die. Optimum design procedure was performed in order to investigated effects on the forming load and the deformed shape of material depending on the die radius profile. Profile of the die surface for the optimum design were suggested with the linear, the cosine and the quadratic curve considering a physical forming process. The surface of each die was modeled using the 3DAutoCAD and the analysis of pilger forming process was performed using the LS-DYNA3D. The optimum profile of the die shape for the pilger mill was determined to the quadratic profile. Since the analysis results provide that the model of the quadratic profile gives the lowest forming load and a proper deformed shape.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1200-1207
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• 2007

An experimental test is presented for photoelastic stress analysis around a crack tip in tensile loaded plate. The hybrid method coupling photoelastsic fringe inputs calculated by finite element method and complex variable formulations involving conformal mappings and analytical continuity is used to calculate full-field stress around the crack tip in uniaxially loaded, finite width tensile plate. In order to accurately compare calculated fringes with experimental ones, both actual and regenerated photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. Regenerated fringes by hybrid method are quite comparable to actual fringes. The experimental results indicate that Mode I stress intensity factor analyzed by the hybrid method are accurate within three percent compared with ones obtained by empirical equation and finite element analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.988-1000
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• 1999

An experimental study is presented for the effect of number of terms of a pewee series type stress function on stress analysis around a hole in tensile loaded plate. The hybrid method coupling photoelastsic data inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width tensile plate. In order to measure isochromatic data accurately, actual photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. For qualitative comparison, actual fringes are compared with calculated ones. For quantitative comparison, percentage errors and standard deviations with respect to percentage errors are caculated for all measured points by changing the number of terms of stress function. The experimental results indicate that stress concentration factors analyzed by the hybrid method are accurate within three percent compared with ones obtained by theoretical and finite element analysis.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.1
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• pp.27-37
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• 1997

The aim of the present study is to investigate experimentally the mechanism of an exploding wire in water and also to observe the bubble motion induced by an exploding wire. The experiment of an exploding wire is carried out in a water tank. As a metallic wire, a tungsten wire of 0.2mm in diameter and 10mm in length is employed. The electric energy of 50-300J is fed to the wire from a capacitor of 100$\mu$F charged up to 1-2.5kV. The explosion is recorded by a CCD camera with the resolution of 1$\mu$sec. The explosion process of metallic wire is divided into three phases. Phase 1 : As the voltage is applied to the wire, the temperature increases due to Joule heating and the wire emits light. Phase 2 : Then the wire melts and the cylindrical plasma is formed between the electrodes. Up to this stage, strong light emission is observed. Phase 3 : The light emission goes out and a vapor bubble begins to grow spherically. The radius of a bubble oscillates in time, but the amplitude of oscillation diminishes in several cycles.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1524-1533
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• 1996

Risidual stress of cylindrical glass rods are measured by photoelasticity to study the variation of stresses with respect to heat treatment temperatures. In order to measure the stresses accurately, fringe sharpening and multiplication techniques are applied to the determination of photoelastic fringe orders. Filon's separationmethod is used to resolve circumferential and redial stress ocmponents from isochromatic fringes which are the same as in-plane maximum shearing stresses. According to the photoelastic measurements, residual stress is increased as the heat treatment temperature of the rods is raised from $560^{\circ}C$ to $650^{\circ}C$ All the circumferential stress components are changed from tensile stresses to compressive ones at approximate $R_m$/$R_o$ = 0.6, where $R_o$/ is outer radius and $R_m$any measured radius. This analysis shows that residual stresses of the glass rods approach zero if the rods are heat-treated near the strain point.

• Resources Recycling
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• v.17 no.5
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• pp.60-65
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• 2008

A study on the removal of silver(Ag) in copper electrolyte was carried out to produce high purity copper by using various method such as ion exchange resin, activated carbon adsorption, copper cementation with powder and wire, CuS precipitation. Parameters, such as reaction time, reaction temperature, addition amount etc. were investigated to determine the effective condition of silver removal. CuS precipitation and ion exchange using Lewatit TP214 was found to be effective. Especially, silver content in copper electrolyte was reduced from 10 ppm to less than 0.1 ppm by ion exchange with Lewatit TP214.

• Korean Journal of Materials Research
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• v.14 no.6
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• pp.399-401
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• 2004

InGaAs/GaAs quantum wire structures were grown by low pressure metalorganic chemical vapor deposition by using selective area epitaxy.$ In_{ 0.2}$$Ga_{0.8}$ As/GaAs quantum wire structures were grown on a $SiO_2$ masked GaAs substrate. Quantum wire structures with sharp tips and smooth side walls were grown. We have grown InGaAs/GaAs quantum wire structures using variously opened width of the $SiO _2$ mask. Even though the opening widths of $SiO_2$ masked GaAs substrate were different, similar shapes of triangular structures were grown. Using various kinds of differently opened $SiO_2$ masked area, it would be possible to grow quantum wire structures with various thicknesses. The quantum wire structures are formed near the pinnacle of the triangular structure. Therefore, the fabrication of the uniquely designed integrated optical devices which include light emitting sources of multiple wavelength is possible.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3300-3309
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• 2000

본 논문에서는 변전소에서 수용가까지의 전력공급설비를 나타내는 도면인 배전설비도면의 주요 기호인 전주와 전선인식 방법에 과하여 기술한다. 제안하는 방법은 원형성에 근거하여 전주후보를 추출한 후 이들 사이의 연결성에 근거하여 전선을 인식한 다음, 전주후보들 중에서 전주를 확인하는 방법으로 다음과 같이 네 개의 단계로 구성된다. 첫 번째는 히스토그램 분석을 통하여 얻어진 임계값을 사용하여 입력영상에서 배전설비영역을 추출하는 단계이고, 두 번째는 추출된 배전설비영역을 세선화 하는 단계이다. 세 번째는 세선영상의 분기점 근처에 정의된 탐색영역에서 원형성을 측정하여 전주후보를 추출하는 단계이다. 네 번째는 전주후보들이 가지는 분기점들 간의 연결성을 측정하여 전선을 인식하는 단계이다. 전선인식이 완료되면 전주후보들 중에서 전선을 가지는 후보들만을 추출하여 전주를 인식한다. 제안된 방법은 한국전력공사의 배전설비도면들 중에서 무작위로 추출한 표본 약 30매를 대상으로 실험하고 그 결과를 제시한다.