• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.94-97
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• 2009

Cast defect in large steel ingots are estimated in quality and compared each other cast conditions on simulation results by now. The cast defects, micro-crack, shrinkage, pin hole which are predictable in simulation with a reasonable accuracy. In this study, 15 ton steel ingot casting was simulated for solidification model and cast defect prediction. And the real cast was carried out in a foundry for the compeer to the simulation results, the cast defect prediction. Also, the quantity of predicted defect was tried to measuring with the defect mach counting for the various simulated cast conditions. The defect quantity work was used to find the optimized cast condition in DOE(design of experiment) procedure.

• Journal of Advanced Marine Engineering and Technology
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• 제23권5호
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• pp.622-629
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• 1999

This paper presents the development of an interactive knowledge-based CAM system for design-ing and manufacturing the mold. The system is composed of two functional parts. One is the geo-metric modeller that uses the feature-based models. The models include base plate step, hole, pocket, boss and slot, These are designed by interactive user interface. The other is the expert sys-tem module with inference engine and knowledge database of workpiece material tools manufac-turing machines process an working conditions. With two parts the final mold shape is generated with manufacturing information for effective production.

• International Journal of Control, Automation, and Systems
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• 제2권3호
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• pp.390-397
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• 2004

This paper presents the design and testing of a multi-channel vibrotactile display. It is composed of a cylindrical handle with four embedded vibrating elements driven by piezoelectric beams. Vibrations are transmitted to the hands through arrays of pins. The device was tested in sensory substitution for conveying force information during a teleoperated peg insertion. Results show that the device is effective in reducing peak forces during the insertion task.

• 전자공학회논문지 IE
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• 제44권1호
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• pp.10-14
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• 2007

InP의 전자와 정공의 이온화계수로부터 추출한 유효이온화계수를 이용하여 InP 다이오드의 항복전압을 위한 해석적 표현식을 유도하였다. 해석적 항복전압 결과를 $N_D=6\times10^{14}cm^{-3}\sim3\times10^{17}cm^{-3}$의 도핑 농도에서 수치적 결과 및 실험 결과와 비교하였다. 각 농도에 따른 해석적 항복전압은 수치 해석적 결과와 매우 잘 일치하였고, 실험 결과와는 10% 이내의 오차로 잘 일치하였다.

• 설비공학논문집
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• 제12권2호
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• pp.181-189
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• 2000

The scroll compressor used for heat pump has a wide range of operation condition. To cover both heating and cooling modes, the operating Pressure ratio ranges from 1.5 to 6.8. Since the scroll compressor, however, is a type of compressor whose pressure ratio is fixed, some loss in the compression work is caused by the operation at the pressure ratio different from the built-in pressure ratio. A way of avoiding this problem is to introduce by-Pass holes in compression chambers, so that the compressed gas of pressure higher than the discharge pressure, yet not reached to the discharge port can be released earlier through the by-Pass holes. In this paper, an optimum Positioning of the by-Pass hole and the effect of the by-pass valve on the compressor performance are studied.

• 한국재료학회지
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• 제25권10호
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• pp.516-522
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• 2015

Aging aircraft structures are inevitably exposed to environment for a long time facing many potential problems, including corrosion and wide spread fatigue damage, which in turn cause the degradation of flight safety. In this study, the environmental surface damages on aging aircraft structures induced during service were quantitatively analyzed. Additionally, S-N fatigue tests were performed with center hole specimens extracted from aging aircraft structures. From the results of quantitative analyses of the surface damages and fatigue tests, it is concluded that corrosion pits initiated during service reduce the fatigue life significantly. Finally, using the fracture mechanics and the EIFS (equivalent initial flaw size) concepts, the remaining fatigue life was predicted based on actual fatigue test results.

• Journal of electromagnetic engineering and science
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• 제14권3호
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• pp.306-313
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• 2014

A Fabry-Perot resonator cavity antenna for Ku-band application is presented in this paper. The Fabry-Perot cavity is formed by a ground plane and a frequency selective surface (FSS) made of a circular hole array. The cavity resonance is excited by a single-feed microstrip patch located inside the cavity. The measured results show that the proposed antenna has an impedance bandwidth of approximately 13% ($VSWR{\leq}2$) and a 3-dB gain bandwidth of approximately 7%. The antenna produces a maximum gain of 18.5 dBi and good radiation patterns over the entire 3-dB gain bandwidth. The antenna's very thin profile, high directivity, and single excitation feed make it promising for use in wireless and satellite communication applications in a Ku-band frequency.

• 산업공학
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• 제13권4호
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• pp.591-598
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• 2000

In this paper, an efficient algorithm is proposed to find parting lines(PL) and generate parting surfaces(PS) for an injection mold design. We used a Face-Edge Graph which can be made by B-rep information of solid model. The graph is useful for finding the peripheral-loop edges for PL and the inner-loop edges for hole-patch. The PS can be generated automatically by selecting pre-defined direction lines. We can create a core and cavity molds by trimming the raw stock block with the PS and the upper/lower faces of a product model. We implemented proposed method with Unigraphics API functions and C language, and tesed on Unigraphics V15.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권8호
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• pp.448-454
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• 2004

In this paper, circular polarized antennas of Tx 30GHz and Rx 20GHz are implemented in LTCC process. Tx antenna has a circular patch structure and Rx antenna has a ring patch structure. The feeding line of Tx antenna is placed in the center hole of Rx ring patch antenna which is printed under Tx circular patch antenna layer. It makes antenna size smaller. Tx antenna's return loss in under -l0dB level from 30GHz to 31GHz and Rx antenna is under -10 dB from 20GHz to 21GHz. The isolation between two antennas is less than -20dB. Axial ratio is less than 3dB thoughout each band.

• 한국전기전자재료학회논문지
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• 제13권2호
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• pp.106-113
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• 2000

This study describes how a properly calibrated simulation method could be used to investigate the latchup immunity characteristics among the various high energy ion implanted CMOS twin well (retro-grade/BILLI/BL) structures. To obtain the accurate quantitative simulation analysis of retrograde well, a global tuning procedure and a set of grid specifications for simulation accuracy and computational efficiency are carried out. The latchup characteristics of BILLI and BL structures are well predicted by applying a calibrated simulation method for retrograde well. By exploring the potential contour, current flow lines, and electron/hole current densities at the holding condition, we have observed that the holding voltage of BL structure is more sensitive to the well design rule (p+to well edge space /n +to well edge space) than to the retrograde well itself.