• Steel and Composite Structures
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• v.29 no.1
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• pp.39-51
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• 2018

Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.2
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• pp.42-51
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• 2001

The effects of pre-indentation technique are presented for A12024-T3 Alclad alloy using as skin material for aircraft fuselage and wing. Indentations were applied to specimens to be placed on the presumed path of fatigue crack growth before fatigue tests. Tension-tension fatigue tests were conducted on the edge cracked specimens in the L-T orientation. Test results were analyzed to investigate the effectiveness of pre-indentation with the variation of specimen's thickness, position of indentation and applied maximum stress. Fatigue crack retardation by pre-indentation is well recognized in the various conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.40-43
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• 1995

In this paper, structual, optical and electrical properties of CdZnS thin films prepared by electron beam evaporation method were studied. The crysta1 structure of CdZnS films deposited was hexagonal type with preferential orientation of the (002) plane parallel to the substrate. The results of optical transmittance of the CdZnS film show that absorption edge is shifted to ZnS and optical bandgap was larger wish increasing ZnS content. The resistivity of the CdZnS film is decreasing with increasing ZnS content and mininum for 20 mole%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1444-1453
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• 1993

비 구조적인 주면 환경에서 평면 팔레트(planar pallet)를 포크리프트(forklift)로 적재하거나 하역하기 위한 물류용 재료운송 로보트 시스템을 제안한다. 제안한 시스템은 음향(acoustic)센서와 시각(visual) 센싱데이타를 사용하여 팔레트에 지정된 2개의 스롯(slot)의 위치를 결정하고 포크리프트를 팔레트의 스롯에 인게즈(engage) 한다. 본 연구에서는 재료운송 시스템의 복잡성을 줄이기 위해서 폴라로이드(Poraloid) 음향센서의 3차원 거리 데이터와 CCD 카메라에서 얻은 2차원 시각 네이타를 통합하는 방법을 개발한다. 2개의 다른 소스로부터 얻은 데이타는 서로의 미비점을 보안하며 재료운송 로보트 시스템을제어하기 위한 효율적인 알고리즘을 제공한다. 카메라는 far-away vision 개념에 의한 음향센서의 선형 스캔닝(scanning) 대역을 우선 결정한다. 선형 스캔닝에 의하여 얻어지는 거리 데이타(range Map)는 least mean square방법을 사용하여 팔레트의 위치와 자세(position and orientation)를 결정한다(near vision). 팔레트에 대한 위치와 자세가 결정되면 다시 시각센서를 이용하여(close vision) 에지(edge)탐지와 Hough transfrom 기술을 적용하여 팔레트에 대한 포크리프트의 인게이지먼트 위치를 구한다. 개발된 시스템은 하드웨어와 소프트웨어로 구현하고 평가하며 실험적인 결과도 제시한다.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.234-239
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• 2003

A cylindrical shape object is widely used as a mechanical part and a water pipe or an oil pipeline which are of cylindrical shape are widely used in the infrastructure. In order to handling such objects automatically using a robot, the posture i.e. orientation in 3D space should be recognized. However, since there is no edge or vertex in the pipe, it is very difficult task for the robot. In this paper in order to guide the robot, two kind of algorithms which find the axis using the measured range data from the robot to the object surface are to be developed. The algorithms are verified using both the simulated range data and the measured one.

• Steel and Composite Structures
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• v.26 no.5
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• pp.649-662
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• 2018

In this study, based on the three-dimensional theory of elasticity, free vibration characteristics of sandwich sectorial plates with multiwalled carbon nanotube-(MWCNT)-reinforced composite core are considered. Modified Halpin-Tsai equation is used to evaluate the Young's modulus of the MWCNT/epoxy composite samples by the incorporation of an orientation as well as an exponential shape factor in the equation. The exponential shape factor modifies the Halpin-Tsai equation from expressing a straight line to a nonlinear one in the MWCNTs wt% range considered. In this paper, free vibration of thick functionally graded sandwich annular sectorial plates with simply supported radial edges and different circular edge conditions including simply supported-clamped, clamped-clamped, and free-clamped is investigated. A semi-analytical approach composed of two-dimensional differential quadrature method and series solution are adopted to solve the equations of motion. The material properties change continuously through the core thickness of the plate, which can vary according to a power-law, exponentially, or any other formulations in this direction. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of laminated sectorial plates.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10b
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• pp.49-53
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• 2006

본 논문에서는 복잡한 배경을 가진 영상에서 손 영역을 안정적으로 검출, 손 형상을 인식하여 그림 맞추기 응용 프로그램을 제어하는 시스템에 대해 기술한다. 피부색의 컬러 정보를 이용하여 손 영역만을 추출한 후 핑거 팁 템플릿매칭을 사용하여 손가락 끝점을 찾아낸다. 또한 손 영역의 에지 방향성 히스토그램을 구하여 얻어진 정보를 바탕으로 주성분 분석법을 사용하여 손 형상을 인식한다. 최종적으로 인식된 손 형상 정보와 손가락 끝점 추적을 이용한 명령어 실행으로 그림 맞추기 응용 프로그램을 제어 한다. 본 논문에서 제안한 알고리즘으로 그림 맞추기 응용 프로그램 제어에 적용한 결과 안정적인 실험 결과를 얻을 수 있었고, HCI 분야에서 다양하게 활용될 수 있음을 확인하였다.

• Journal of the Korean institute of surface engineering
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• v.31 no.1
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• pp.24-33
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• 1998

Effects of pH and supporting salts on the characteristics of electrogalvanzied coating in sulfate bath are investigated. The fine grain size is obtained and the whiteness with the amount of supporting salts or pH increased at more than current density of 100A/$dm^2$<\TEX>, With supporting salts increased, the electro-conductivity of the bulk solution increases and the cell voltage decreases, while the width of the cathode burned edge gets wider because it seems that the increased overpotential the vicinity of cathode causes the decreases, of limiting current density. When the amount of supporting salts or pH of sulfate bath decreases, the zinc crystals have preferred orientation (001) planes. However when the amount of supporting salts or pH increase, the crystal texture has less (001) planes and gets to have random crystal planes.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.399-399
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• 2011

We studied the structural and optical characterization of zinc sulfide (ZnS) thin films by RF magnetron sputtering on glass substrates. The substrate temperature was varied in the range of 100$^{\circ}C$ to 400$^{\circ}C$. The XRD analyses indicated that ZnS films had cubic structures with (111) preferential orientation and grain size varied from 20 to 60 nm, increasing with substrate temperatures. The optical properties were carried out by UV-visible spectrophotometer. Transmission measurement showed that the films had more than 70% transmittance in the wavelength larger than 400 nm, and the absorption edge shifted to shorter wavelength with the increase of substrate temperatures.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.1
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• pp.40-47
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• 2010

This paper presents a simultaneous localization and mapping (SLAM) of an indoor hallway environment using Rao-Blackwellized particle filter (RBPF) along with a line segment as a landmark. Based on the fact that fluent line features can be extracted around the ceiling and side walls of hallway using vision sensor, a horizontal line segment is extracted from an edge image using Hough transform and is also tracked continuously by an optical flow method. A successive observation of a line segment gives initial state of the line in 3D space. For data association, registered feature and observed feature are matched in image space through a degree of overlap, an orientation of line, and a distance between two lines. Experiments show that a compact environmental map can be constructed with small number of horizontal line features in real-time.