• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.59-65
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• 2011

According to the trends of electronic package to be smaller, thinner and more integrative, Flip Chip Ball Grid Array (FCBGA) become more used for mobile phone. However, the flip chip necessarily generate the heat by the electrical resistance and generated heat is increased due to reduced distribution area of the heat in accordance with the miniaturization trend of the package. Thermal issues can result in problems of devices that are sensitive to temperature and stress. Then the heat can generate problems to the system. In this paper, in order to improve the thermal issues of FCBGA, thermal characteristics of FCBGA was analyzed qualitatively by using the general heat transfer module of Comsol 3.5a and In order to solve thermal issues, flip chip with new micro structure is proposed by the simulation. and also by comparing existing model and analyzing variables such as pitch, height of the pattern and shape of the heat spreader, the improvement of heat dissipation characteristics about 18% was confirmed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.1
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• pp.75-83
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• 1989

In this paper, applying the REC model which characterizes the coupling between the radiating edges to two coupled rectangular microstrip patch antenna, we obtain scattering parameters $\mid$ $S_{11}$ $\mid$ and $\mid$ $S_{12}$ $\mid$for the various coupling separations, Se=0.5mm, 1.0mm, 1.5mm, and 2.0mm, The calculated values are compared with the measured values. For the rectangular microstrip patch antenna with a parasitic element which is gap-coupled to the radiating edges of the rectangular patch, calculated return losses using the REC model are compared with measrued values. Here, the each microstrip antenna is fed by a 50 microstrip line. The purpose of the paper is to compare a 50$\Omega$ microstrip line fed case with a coaxial fed case treated in Ref.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.139-145
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• 2008

In this paper, a microstrip surface wave antenna(SWA) with a frequency selective surface structure(FSS) is designed and measured. A microstrip SWA has many advantages such as low profile, low weight, easy fabrication, and compatibility with monolithic microwave integrated circuits(MMIC). In addition, it has demonstrated monopole like beam patterns. The microstrip SWA consists of two parts : a center-fed modified microstrip patch to excite surface wave, and a periodic patches to support the propagation of the surface waves. To obtain wide bandwidth, the ring type parasitic element is inserted and the circular patch is selected for the unit element in FSS structure. Experimental results show that the microstrip SWA has monopole like beam patterns at 5.9GHz. Impedance bandwidth and gain is 12% and 5.6dBi.

• Journal of the Korean Magnetics Society
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• v.17 no.3
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• pp.141-146
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• 2007

A new class of LC-resonator for micro magnetic sensor device was invented and fabricated by means of MEMS technique. The micro LC-resonator consists of a solenoidal micro-inductor with a bundle of soft magnetic microwire cores and a capacitor connected in parallel to the micro-inductor. The core magnetic material is a tiny glass coated $Co_{83.2}B_{3.3}Si_{5.9}Mn_{7.6}$ microwire fabricated by a glasscoated melt spinning technique. The core materials were annealed at various temperatures $150^{\circ}C,\;200^{\circ}C\;,250^{\circ}C\;,$ and $300^{\circ}C$ for 1 hour in a vacuum to improve soft magnetic properties. The solenoidal micro-inductors fabricated by MEMS technique were $500{\sim}1,000{\mu}m$ in length with $10{\sim}20$ turns. The changes of inductance as a function of external magnetic field in micro-inductors with properly annealed microwire cores were varied as much as 370%. Since the permeability of ultra soft magnetic microwire is changing rapidly as a function of external magnetic field. The inductance ratio as well as magnetoimpedance ratio (MIR) in a LC-resonator was varied drastically as a function of external magnetic field. The MIR curves can be tuned very precisely to obtain maximum sensitivity. A prototype magnetic sensor device consisting of the developed microinductors with a multivibrator circuit was test successfully.

• The Science & Technology
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• v.33 no.5 s.372
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• pp.74-75
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• 2000

서울대 물리교육과에서 마이크로웨이브 소자에 관한 공동연구를 위해 지난 98년 12월 한국에 온 중국 과학자 Baoju Jia박사는 현재 박건식 교수팀과 함께 광대역에서 전자파를 발생하는 진행파관에 대한 연구를 계속하고 있다. 91년부터 중국전자과학기술대 교수로 재직해온 Baofu Jia박사는 "한국에서는 중국과는 달리 대부분의 연구과제가 일상생활과 밀접한 관계가 있어 연구결과를 시장에 쉽게 연결할 수 있는 장점이 있다."고 말한다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.77-81
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• 2002

에디슨이 백열전구를 발명하면서 본격적인 조명의 발전이 이루어졌다. 현재까지 조명등의 주류로서 백열전구와 형광등이 자리 잡고 있으며, 고압 방전등의 개발과 더불어 옥외조명에서도 급속히 발전하고 있다. 특히 방전등과 같은 안정기가 필요한 조명등의 경우 전력전자용 반도체 소자와 마이크로프로세서의 획기적 발전 속도에 맞추어 고효율, 고전력화로 접목되고 있다. 다른 전력전자 응용 분야에 비해서 조명에 적용되는 것은 미미한 실정이지만 한편으로는 향후 많은 조명제어 부분에 기술적용이 가능하다. 본 논문에서는 일반적인 조명등과 안정기, 조명제어 기술 동향을 조사하여 향후 조명등과 조명기술의 발전에 도움이 되고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.525-526
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• 2010

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.54.1-54
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• 2003

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.188-195
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• 2004

In this paper, we fabricated fluidic devices like micro-channel, pump, mixer and particular gas separator with the technology of stereolithouaphy using RP(rapid-prototyping). The fabricated fluidic devices are expected to be applied to develop Lab-on-a chip type liquid analyzer. Stereolithography technology seems effective for fabricating MEMS(Micro Electro Mechanical System) with complicated structure because it makes three dimensional fabrication possible but, exclusive devices are needed to be developed fur fabricating even more microscopic MEMS structure.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.262-263
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• 2000

이온교환방법은 착색된 유리를 생산하기 위하여 수세기 전부터 연구되어 왔다. 1972년 Izawa와 Nagome가 silicate 유리에 Tl$^{+}$이온을 치환하여 평판 도파로를 만든 후, 이온교환은 도파로나 마이크로 렌즈제작 등에 활발하게 연구되어 왔다. 유리 도파로는 광의 진행손실이 적으며, 광섬유와의 우수한 호환성, 그리고, 제작이 용이하고 가격이 싼 장점 등으로 인하여 많은 연구가 진행되고 있는 재료이다. 그러나, 유리에 이온교환으로 광소자를 만들기 위해서는 굴절률변화를 정확하게 예측해야한다. 따라서, 유리에서 이온들의 확산특성을 정확하게 분석하고 실험적으로 확립하는 연구는 매우 중요하다고 하겠다. (중략)