• Journal of the korean Society of Automotive Engineers
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• v.12 no.6
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• pp.48-59
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• 1990

A finite element program was developed using line elements for simulating the stretch/draw forming operation of an arbitrarily-shaped plane-strain section. An implicit, incremental, updated Lagrangian formulation is employed, introducing a minimum plastic work path assumption for each time step. Geometric and material nonlinearities are also considered within each time step. The finite element equation is based on the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The membrane approximation is adopted under the plane stress assumption. The sheet material is assumed to obey a rigid-viscoplastic constitutive law. The developed program was tested in the die-tryout of typical automotive inner panels. In order to determine a single friction coefficient and boundary length, FEM results and measurements of thinning for a stretched section of final die were compared. After finding analysis parameters, the sheet forming operations of original and final die designs were simulated. Excellent agreement between measured and computed thickness strains was obtained and the developed program was able to identify die designs which were rejected during die tryout.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1403-1410
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• 1997

Because streaming mode connection server suitable to wide area ATM networks performs transmission, reception and lookup with time restriction for the transmission time of a cell, it has demerits of large cell loss incase that burst traffic occurs. Therefore, in this paper to decrease cell loss we propose a high speed CAM (Content Addressable Memory) which is capable of processing data of streaming mode connections server at a high speed. the proposed CAM is applied to forwarding table VPC map which performs function to output connection numbers about input VPI(Virtual Path Identifier)/VCI(Virtual Channel Identifier). The designed high speed CAM consist of DBL(Dual Bit Line) CAM structure performed independently write operation and match operation and two-port SRAM structure. Also, its simulation verification and full-custom layout is performed by Hspice and Composs tools in 0.8 .$\mu$m design rule.

• Proceedings of the Safety Management and Science Conference
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• 2003.11a
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• pp.285-290
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• 2003

This paper describes the NC simulator system for Wire-cut electrodischarge machining. Electrodischarge Wire-cut machining is applicable to all materials including metals, alloys, and most carbides. Although CAM system generate the NC code considering electrodischarge conditions, incorrect Wire-cut tool path bring about fatal results. The simplest way of simulating a EDM process is to display the trajectory of Wire-cutter location by line segments. With this kind of simulation, the programmer can get a general idea about whether the wire is moving as planned but cannot locate gouging or excess material because only the wire location will be seen, not the changes in the workpiece as it is machined. The ideal way of simulating the EDM process is to display the solid model of the workpiece as it is machined. Therefore we propose the ideal NC simulator system for Wire-cut EDM.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.57-62
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• 2005

본 연구는 공기청정기의 성능에 영향을 미치는 인자로서 홉입구, 배기구의 위치 및 형상, 그리고 실내 공간상 배치 등에 대해 수치해석에 의한 모사를 통하여 평가하였다. 해석방법으로는 먼저 유동장을 해석한 후 고정된 유동장 내에서의 먼지 입자의 거동을 검토하였다. 배기구 위치에 의한 성능해석 결과는 배기구를 상면에 위치하게 할 경우 양 측면에 위치한 구조보다 우수한 성능을 나타내었으며, 설치위치에 대한 성능해석 결과는 제한적이나 현관 옆에 설치할 경우 해석된 두 가지 모델 모두 우수한 성능을 나타내었다.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.55.2-55.2
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• 2013

We present the observational study of parsec-scale jets from YSOs reaching lengths of several arc-minutes. The medium-resolution spectroscopic data were obtained between 6000 - $7000{\AA}$ with BOAO long-slit spectrograph. By performing multi-position observation, we investigated the physical variation of the jets and the ambient gas along the whole path of the jets. The flux, electron density, ionization fraction, and electron temperature are discussed with the estimated line ratios between from [OI], [NII], $H{\alpha}$ and [SII] emission lines. This study carried out with more than 8 jets of YSOs including low- to intermediate-mass stars. We also briefly discuss the kinematics of the outflows using spatial and spectroscopic data.

• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.29-36
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• 2000

Surface micro-crack grows along intergranular or transgranular region of crystal grains. But if it meets the barrier such as sessile dislocation and precipitates it loses straightness and deflects. Investigators had many difficulties in estimating fatigue life of smooth specimen because of the random distribution growth and coalescence of surface micro-cracks. The path of surface micro-crack has irregularity due to nonhomogeneous microstructure. Euclidian geometry can't quantify the shape of surface micro-crack but fractal geometry can. Therefore in this paper fractal dimension is measured at various stage of cycle ratio and estimated cycle ratio in 2024-T3 aluminium, alloy.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.117-120
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• 2003

PON (Passive Optical Network) is an emerging local subscriber access architecture that provides more bandwidth and services to subscriber than DSL (Digital Subscriber Line and HFC (Hybrid-Fiber Coaxial) network. A PON is a point-to-multipoint optical network with no active elements in the signals' path from source to destination. Advantages of using PON for a subscriber access network include large coverage area, reduced fiber deployment, multicast and broadcast capabilities, reduced cost of maintenance (due to devices being passive), and ease of upgrades to higher bit rate or additional wavelengths. PON uses WDM (Wavelength Division Multiplexing) technique that transmits the downstream and upstream data at each different wavelength. For transmitting the CATV (Community Antenna television) service through PON network, we give out additional wavelength. This study shows the available TPS (Triple play service) architecture using CATV overlay EPON (Ethernet PON) architecture and analyzes the effects of EPON-based CATV transmission by measuring the power loss fur each wavelength and the power range of the available analog wavelength and RF.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.177-182
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• 1997

A visual servoing method is proposed for a robot with a camera in hand. Specifically, vanishing point features are suggested by employing a viewing model of perspective projection to calculate the relative rolling, pitching and yawing angles between the object and the camera. To compensate dynamic characteristics of the robot, desired feature trajectories for the learning of visually guided line-of-sight robot motion are obtained by measuring features by the camera in hand not in the entire workspace, but on a single linear path along which the robot moves under the control of a commercially provided function of linear motion. And then, control actions of the camera are approximately found by fuzzy-neural networks to follow such desired feature trajectories. To show the validity of proposed algorithm, some experimental results are illustrated, where a four axis SCARA robot with a B/W CCD camera is used.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2464-2466
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• 1998

A switch is a component with two or more ports that selectively transmits, redirects, or blocks optical power in a fiber transmission line. Our switch uses rotation mechanism using stepping motor, hence the common optical fiber can scan and allign to one of the arrayed N optical fibers to provide optical path by electronic precise control. The developed switch is consisted of switching module and its control module. The performance parameters of a switching loss and a repeatability are considered very important. We performed the study to reduce the switching loss and improve the repeatability of switch. The switch can be widely used as a test instrument of optical device and of optical cable in factory, also of optical cable monitoring systems.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.62-69
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• 1996

In this study, an equivalent domain integral (EDI) method is presented to estimate the track-till integral parameter, J-value, for two dimensional cracked elastic bodies which may quantify the severity of the crack-tit) stress fields. The conventional J-integral method based on line integral has been converted to equivalent area or domain integrals by using the divergence theorem. It is noted that the EDI method is very attractive because all the quantities necessary for computation of the domain integrals are readily available in a finite element analysis. The details and its implementation are extened to both h-version finite element model with 8-node isoparametric element and p-version finite element model with high order hierarchic element using Legendre type shape fuctions. The variations with respect to the different path of domain integrals from the crack-tip front and the choice of 5-function have been tested by several examples.