• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.1940-1945
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• 2006

The small and wideband annular ring slot antenna with eccentric radiating structure and low impedance feedline is presented. This antenna is analyzed by using substrate with permittivity 4.3 and thickness 1mm. As the measured impedance bandwidth of proposed antenna is $118%(S_{11}{\leq}-10dB)$, its bandwidth is much broader than that of conventional annular ring slot antenna.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.07a
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• pp.114-118
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• 2001

졸-겔법으로 Pt/Ti/$SiO_2$/Si 기판위에 $Bi_{3.7}$/$La_{0.75}$$Ti_3O_{12}$(BLT) 강유전체 박막을 형성하였다. As-coated BLT 박막은 $600^{\circ}C$의 후속 열처리온도에서 결정화 되었으며 전형적인 Bi 층상 페롭스카이트 결정구조를 나타내었다. 또한 후속 열처리온도를 증가함에 따라 결정성이 향상되었다. $700^{\circ}C$의 온도에서 후속 열처리된 BLT 박막의 비 유전상수($\varepsilon_{r}$)와 유전손실($\textrm{tan}\delta$)은 5KHz 주파수에서 약 402와 0.04를 각각 나타내었다 $800^{\circ}C$에서 후속 열처리된 BLT박막의 경우 5V의 인가 전압에서 잔류분극 2Pr($Pr^{+}$-$Pr^{-}$)값은 약 32.5$\mu$C/$Cm^2$을 나타내었다.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.90-96
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• 2006

A novel high power factor drive of a single-phase switched reluctance motor (SRM) is researched. It achieves sinusoidal and near unity power factor input currents. The proposed SRM drive has one additional active switches. And a single-stage approach has a simple structure and low cost. A prototype to drive an SRM equipping a suitable encoder is designed to evaluate the proposed topology. The characteristics and validity of the proposed circuit is discussed with some simulations and experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.46-50
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• 2004

The curing characteristics of a liquid photopolymer during microstereolithography and the shape accuracy of thereby fabricated microstructures were investigated experimentally. A He-Cd laser with a wavelength of 442nm and a photopolymer consisted of a commercial resin from SK chemical and a photoinitiat or were used for the experiment. By varying the laser beam power and scanning speed of the focused laser beam, minimum curing thickness of 50 ${\mu}ㅡ$ was obtained. The distortion of solidified structure due to adhesion force was measured and the optimum fabrication conditions were determined. Also, the feasibility of direct fabrication of three-dimensional microstructures by Super IH process was examined.

• Journal of computational fluids engineering
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• v.11 no.4 s.35
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• pp.101-106
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• 2006

In the microfluidic devices the most important thing is mixing efficiency ol various fluids. In this study a newly designed miler is proposed to enhance the mixing effect with the purpose to apply it to microchannel mixing in a short future. This design is composed of a channel with cross baffles periodically arranged on the both bottom and top surfaces ol the channel. To obtain the yow patterns, the numerical computation was performed by using a commercial code, ANSYS CFX 10.0. To evaluate the mixing performance, we computed Lyapunov exponent and obtained Poincare sections. it was shown that our design provides the excellent mixing effect.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.159-162
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• 2006

In the microfluidics devices the most important thing is mixing efficiency of various fluids. In this study a newly designed mixer is proposed to enhance the mixing effect with the purpose to apply it to microchannel mixing in a short future. This design is composed of a channel with cross baffles periodically arranged on the both bottom and top surfaces of the channel. To obtain the flow patterns, the numerical computation was performed by using a commercial code, ANSYS CFX 10.0. To evaluate the mixing performance, we computed Lyapunov exponent and obtained Poincare sections.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1088-1091
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• 1997

This paper describes the characteristic of hinges on which a lever pivots within a limited angle due to the torque. The hinges are exerted by the thermally expanded actuators connected with a level through hinges. To enhance the stroke of inchworm actuator, FEM(Finite Element Method) was utilized for the characterization in view of stress displacement according to the variation of notch radius and notch width. As a result, notch width of the hinges plays an important part in improvement of micro inchworm actuator.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.1
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• pp.31-38
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• 1998

저온소결기판용 Glass-ceramics를 제조하기 위해 LiO2-MgO-MgF2-SiO2계 조성에 서 B2O3첨가가 결정화 특성 및 물성에 미치는 영향을 고찰하였다. 145$0^{\circ}C$에서용융하여 제조 한 모유리의 핵형성 온도와 결정화 온도를 결정하기 위해 TMA와 DTA분석을 실시하였다. 결정화시킨 유리의 결정상과 미세구조를 관찰하기 위하여 XRD와 SEM관찰을 실시하였다. Water swelling을 통해 Glass-ceramics powder를 제조하였으며 제조한 powder의 평균입자 크기는 8.32$\mu$m였다.

• Journal of the Microelectronics and Packaging Society
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• v.5 no.2
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• pp.21-26
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• 1998

대용량, 고속데이터 처리가 요구되는 System 개발은 이들의 복잡하고 고기능의 회 로 구현이 가능하냐에 달려 있고 또한 이들고기능 요구를 가장 잘 만족할수 있는 패키지는 MCM 이라 할 수있다. 시스템의 고속화, 소형화는 회로의 복잡성을 요구하는 있는 이를 패 키지로 구현하는 MCM은 시험성 확보에 심각한 문제점으로 나타나고 있다. 본 논문에서는 고밀도 구조의 MCM 기판에 대한 Interconnetion Line 시험검증을 위한 Flying Prober의 적 용 및 모듈 패키징 공정에 대한 조립성 검증을 위한 BST에 대해 설명한다. 연구에 사용된 MCM 모듈은 MCM-D 공정으로 제작되었으며 31um 신호선폭, 50um Via Hole Dia. 5신호 선층 5절연층 및 455 Net의 기판으로절연층은 Dow chemical의 BCB-4024/4026을 적용하였 다. 조립은 3 ASIC, 24소자 실장 및 2000 Wire Bonding으로 이루어지며 패키지는 방열특성 을 고려한 BGA(491 I /O,50mil pitch)를 개발하여 사용하였다. MCM 기판의미세패턴으로 구성된 Interconnection Line에 대해 Fine Ptich Probing이 가능한 Flying Prober를 사용하 여 평가하였으며 BST를 이용하여 실장소자의 KGD평가 및 능동, 수동소자가 실장된 MCM Package의 조립시험성을 확보할수 있었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.213-217
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• 2012

In this paper, we design dual-band microstrip antenna for IEEE 802.16e mobile WiMAX standard IEEE 802.11 WLAN band at the same time. To solve interference at the desired operating frequency band, impedance matching is improved and simple production method showed the characteristics of the omni-directional and compact size. The proposed structure is considered to bring the effect of the installation costs, and show the antenna for dual-band communication.