• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1875-1882
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• 2013

Micro-array technology contributes numerous achievements such as ordering of gene network and integration of genomic. This technology is well established as means for investigating patterns of gene expression. DNA micro-arrays utilize Affymetric chips where a large quantity of DNA sequences may be synthesized. There are two general type of conventional DNA array spotter: contact and piezoelectric. The contact technology used spotting pin technology to make contact with the glass slide surface. This may caused damage or scratches to the surface matrix where protein will be contaminated and may not bind specifically. Piezoelectric technology available at this present time on the other hand requires the analyzer to print the result that can only be done within the laboratory despite of mass production. Therefore, in this paper, high-throughput technology is developed for providing greater consistency in feature spot without touching the glass slide surface.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.547-552
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• 2007

In this paper, the coupled microstrip lines of hairpin type are applied to design a compact microstrip ring hybrid. When the gap decreases, three attenuation poles are created by coupling between the lines. The proposed structure can achieve a significant reduction of size and suppression of the harmonics. And it has the same frequency responses of conventional ring hybrid at 2.55 GHz. The harmonics are suppressed to below -20 dB up to 12 GHz, including the third harmonic. The ring part size of the proposed ring hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.1
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• pp.9-17
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• 2010

In this study, von Mises stress and total strain energy density characteristics of lead pin in PGA (Pin Grid Array) packages have been calculated by using the FEM (Finite Element Method). FEM computation is carried out with various heat treatment conditions of lead pin material under $20^{\circ}$ bending and 50 mm tension condition. Results show that von Mises stress locally concentrated on lead pin corners and interface between lead pin head and solder. von Mises stress and total strain energy density decrease as heat treatment temperature of lead pin increases. Also, round shaped corner of lead pin decreases both von Mises stress and total strain energy density on interface between lead pin head and solder. This means that PGA package reliability can be improved by changing the mechanical property of lead pin through heat treatment. This has been known that solder fatigue life decreases as total strain energy density of solder increases. Therefore, it is recommended that both optimized lead pin shape and optimized material property with high lead pin heat treatment temperature determine better PGA package reliability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1087-1092
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• 2010

A micro 3D-PTV system has been constructed using a single camera system. Two viewing holes were created behind the object lens of the microscopic system to construct a stereoscopic viewing image. A hybrid recursive PTV algorithm was used. A concept of epipolar line was adopted to eliminate many spurious candidates. Three-dimensional velocity vector fields were obtained by calculating the three-dimensional displacements of particles that were identified as being identical. The system consists of a laser light source (Ar-ion, 500 mW), one high-definition camera ($1028{\times}1024$ pixels, 500 fps), a circular plate with two viewing holes, and a host computer. The performance of the developed algorithm was tested using artificial images. The characteristic of the vector recovery ratio was investigated for the particle numbers. A micro backward-facing step channel ($H{\times}h{\times}W:\;36{\mu}m{\times}70{\mu}m{\times}3000{\mu}m$) was measured using the developed measurement system. The results were in good qualitative agreement with other results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.457-463
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• 2016

In this paper, a method of enhancing the bandwidth of a double-dipole quasi-Yagi antenna (DDQYA) using a modified integrated balun is presented. The modified integrated balun consists of a microstrip (MS) line inserted along the center of a coplanar strip (CPS) line and the end of the MS line is connected to the CPS line through a shorting pin at the feed point. The geometry of the modified integrated balun is adjusted to improve the bandwidth of the DDQYA. In addition, the performance of the proposed balun in a back-to-back configuration is compared with a conventional balun. The proposed antenna with the optimized modified integrated balun is fabricated on an FR4 substrate, and the experiment results show that the antenna has a frequency band of 1.56-3.04 GHz(64.4%) for a VSWR < 2, which shows enhanced bandwidth compared to the DDQYA with the conventional balun.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.397-401
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• 2005

In this paper, a slot-coupled microstrip antenna with switchable polarization is proposed for the polarization diversity applications in the complicated communication environment. The proposed antenna is fed by a microstrip line through one of two slots located with the interval of $\lambda{g}/4$ in the ground plane. By switching the PIN diode between opened and shorted termination which is located at the tip of the microstrip line, the switching function between horizontal and vertical polarization was confirmed experimentally. The measured resonant frequencies of the fabricated antenna are $2.41\;\cal{GHz}\;2.40\;\cal{GHz}$ and the cross polarization levels are $19\;\cal{dB},\;23\;\cal{dB},\;the\;-10\;\cal{dB}$ return loss bandwidths are $95\;\cal{MHz}\;100\;\cal{MHz}$ in horizontal and vertical polarization, respectively, and the antenna gain is almost $6\;\cal{dBi}$.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.18-24
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• 2003

The resonator using two layer microstrip structure was proposed and the bandpass filter was designed using this resonator in this paper. The proposed resonator structure is constructed by placing a U-shape of resonator in the first layer and then placing a broadside coupling strip in the second layer just above of the U-shape of resonator's edge part. Because these structure has various design parameters than general single layer coupled line structure, filter design is more flexible. In this paper, the narrow band filter was designed using multi-layer structure that had been applied to broadband filter because it's high coupling nature. The filter was designed to have 4MHz center frequency and 3 % fractional bandwidth, and finally confirmed that can be realizable narrow band filter by using multi-layer structure through fabrication and measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.158-158
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• 2016

최근 유연정보전자소자의 개발이 대두되고 있다. 이러한 개발 동향에 맞춰 정보전자소자의 각 소재를 유연화하는 연구가 진행되고 있다. 이 중 ITO 기반의 기존 투명전극은 투명전극으로써는 매우 높은 성능을 보이지만, 유연성이 매우 낮기 때문에 대체 투명전극에 대한 연구가 필수적이다. 그래핀, 전도성 고분자, Oxide/metal/oxide, 금속나노와이어 등 다양한 유연 투명전극에 대한 연구가 진행되고 있으나 ITO 급의 면저항/투과도를 얻지 못하고 있다. 은나노와이어는 ITO 대체로 주목받는 투명전극 중에 면저항/투과도가 가장 ITO에 유사하면서, 유연성까지 지니고 있는 장점을 가지고 있다. 반면 약 100 nm 직경의 1차원 나노와이어가 랜덤하게 분포되어 있기 때문에, 위치별로 균일성에 대한 이슈가 존재하고, 표면 조도가 매우 높기 때문에 (ITO ~ 1 nm, AgNW > 20 nm) OLED에 적용하기 어려운 문제가 존재한다. 또한 대면적 OLED에 적용하기에는 여전히 저항이 높은 문제가 존재한다. 본 연구에서는 이러한 은나노와이어의 높은 저항 문제를 해결하기 위해, 마이크로 급의 미세금속배선을 보조배선으로 도입하였다. 이러한 보조배선을 통해 대면적 소자에도 전류가 잘 흐를 수 있고, 이러한 전류가 은 나노와이어를 통해 소자 전면적에 균일하게 도달하여, 대면적에서 균일한 발광을 하게 된다. 본 은나노와이어/금속보조배선 구조는 면저항 4 ohm/sqr., 투과도 90%를 달성하였고 이는 기존 ITO보다 우수한 수치이다. 더욱이, 유연성까지 함께 확보하고 있어 유연 전극으로써의 활용도 충분히 가능하다. 이를 활용해 OLED를 제작한 결과 밝기와 발광균일도가 기존의 ITO를 활용한 것보다 훨씬 높아짐을 확인할 수 있었다.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.112-114
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• 1999

Superconducting multiplexer consisting of hairpin type filters has been designed for the reduction of the physical size of the device. Pulsed laser deposition with a Nd:YAG laser has been used to grow high quality YBCO superconducting films on MgO substrates. Multiplexer has been designed to have the center frequencies at 13.6 CHz and 13.9 GHz on MgO substrate with the size of 20 ${\times}$ 20 ${\times}$ 0.5mm$^3$. It is possible to implement superconducting multiplexer having two passbands on the limited 20 ${\times}$ 20 ${\times}$ 0.5mm$^3$ MgO substrate by adopting hairpin type filters. This type of superconducting device will be useful for the integration of microwave subsystem.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1725-1734
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• 1996

Experimental condensation and evaporation heat transfer coefficients were measured in a horizontal smooth tube and a horizontal micro-finned tube with HFC-134a. The test sections are straight, horizontal tubes with have a 9.52mm outside diameter and about 5000mm long. The micro-finned tube had 60 fins with a height of 0.12mm and a spiral angle of 25.deg.. The condensation test section was a double-pipe type with counter flow configuration. The evaporation test section employed an electic heating method. Enhancement factors which is defined as a ratio of the heat transfer coefficient for micro-finned tube to that for smooth tube, varied from 1.3 to 1.6(mass flux:110~190kg/m$^{2}$s) for condensation and 1.2 to 1.5 (mass flux:70~160kg/m$^{2}$s) for evaporation. The experimental data of condensation and evaporation heat transfer coefficients were compared to several empirical correlations. Based on these comparisons, modified correlations of the condensation and evaporation heat transfer coefficient for both smooth and micro-finned tubes were proposed.