• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.501-507
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• 2003

In this study, microscale, high-performance, solenoid-type RF chip inductors were investigated. The size of the RF chip inductors fabricated in this work was 1.0${\times}$0.5${\times}$0.5㎣. 96% $Al_2$ $O_3$and I-type were used as the material and shape of the core, respectively. The copper (Cu) wire with 6 turns was employed as the coils. The diameter (40${\mu}{\textrm}{m}$) and position (middle) of the coil and the length (0.35mm) of solenoid were determined by a high-frequency structure simulator (HFSS) to maximize the performance of the inductors. High frequency characteristics of the inductance (L) and quality-factor (Q) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The inductors developed have inductances of 10.8nH and quality factors of 25.2 to 50 over the frequency ranges of 250MHz to l GHz, and show results comparable to those measured for the inductors prepared by CoilCraf $t^{Tm}$ . The simulated data predicted the high-frequency data of the L and Q of the inductors developed well.l.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1140-1147
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• 2001

Experimental schemes that enable characterization of phase-change phenomena in the microscale regime are essential for understanding the phase-change kinetics. Particularly, monitoring rapid vaporization on a submicron length scale is an important yet challenging task in a variety of laser-processing application, including steam laser cleaning and liquid-assisted material ablation. This paper introduces a novel technique based on Michelson interferometry for probing the liquid-vaporization process on a solid surface heated by a KrF excimer laser pulse(λ=248nm, FWHM=24ns) in water. The effective thickness of a microbubble layer has been measured with nanosecond time resolution. The maximum bubble size and growth rate are estimated to be of the order of 0.1㎛ and 1m/s, respectively. The results show that the acoustic enhancement in the laser induced vaporization process is caused by bubble expansion in the initial growth stage, not by bubble collapse. This work demonstrates that the interference method is effective for detecting bubble nucleation and microscale vaporization kinetics.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1539-1542
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• 2005

We have introduced polyelectrolyte micro-patterning technique employing agarose plane stamp and a hard substrate having microscale features on its surface. With this method, chemically micropatterned surfaces with both positive and negative functionalities were successfully embedded in well-defined microstructures, and selective impartment of charge functionalities was confirmed by patterning bead bearing surface charge. Furthermore, this technique allows highly sensitive immobilization of protein onto targeted surface simply by endowing functionalities, which extends the potential of its use as a tool for high-throughput protein microarray and proteomics. Because plane agarose stamp is free of structures on its surface, there is no concern for pattern collapse, and the combination of agarose plane stamp with patterned substrate is more suited for selective protein patterning compared with adopting surface-patterned agarose stamp with flat substrate. Our technique using agarose plane stamp and a substrate having microscale features on its surface suggests a range of possible applications, including the micropatterning of biofunctionalized copolymer having polyelectrolyte block, immobilization of micro- and nanoparticle with biofunctionalities such as biotin and streptavidine, and establishing optoelectronic microstructures with micro-beads on various surfaces.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.07a
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• pp.1-20
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• 2001

• 한국생태학회:학술대회논문집
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• 1999.05a
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• pp.31-41
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• 1999

• 한국가시화정보학회:학술대회논문집
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• 2003.05a
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• pp.31-46
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• 2003

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.46-49
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• 2006

Extinction limits and combustion temperatures in heat-recirculating excess enthalpy reactors employing both gas-phase and catalytic reaction have been examined previously, with and emphasis Reynolds number (Re) effects and possible application to microscale combustion devices. However, Re is not the only parameter needed to characterize reactor operation. In particular, the use of a fixed reactor size implies that residence time and Re cannot be adjusted independently. To remedy this situation, in this work geometrically similar reactors of different physical sizes were tested with the aim of independently determining the effects of Re and Da. It is found that the difference between catalytic and non-catalytic combustion limits narrow as scale decreases. Moreover, to assess the importance of wall thermal conductivity, reactors of varying wall thickness were studied. From these results the effect of scale on microscale reactor performance and implications for practical microcombustion devices are discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.123-123
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• 2012

초소수성 표면은 150도 이상의 높은 물 접촉각과 10도 이하의 낮은 sliding angle을 가지며 self-cleaning, anti-contamination 기능을 갖고 있는 것이 특징이다. 재료표면의 친수성과 소수성을 제어하기 위해서는 화학적 인자인 물질의 표면에너지나 물리적 인자인 표면 거칠기를 조절하는 방법이 있다. 초소수성 표면을 구현하기 위해서는 표면의 거칠기를 증가시키거나 표면 에너지를 낮춰야 하는데 고체 표면의 거칠기를 증가시키기 위해서는 일반적으로 표면에 microscale과 nanoscale의 계층구조를 형성시키는 방법이 사용된다. 자연계에 매우 풍부하게 존재하는 실리카는 내구성과 내마모성, 화학적 안정성, 고온 안정성 등을 지니고 있으며 인체에 무해하기 때문에 다양한 종류의 전자기기 및 부품의 내외장 코팅에 적용이 검토되고 있다. 이러한 관점에서 본 연구에서는 초소수성 코팅층을 구현하는 하나의 방법으로서 졸-겔방법으로 실리카 졸을 합성하여 전기분무법을 사용하여 microscale의 실리카 입자 코팅층을 형성하였으며, 표면 미세구조 조절 및 계층구조 형성과 불소화처리 공정을 통하여 초소수성 실리카 코팅층을 제조하였다. 이러한 초소수성 실리카 코팅층의 표면거칠기, 자외선 영향향, 내구성 등을 초소수성 관점에서 평가하였다.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.430-435
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• 2001

This paper introduces a pressure correction method for microflow computation. Conventional CFD methods with no slip boundary condition fail to predict the rarefaction effect of the wall when simulating gas microflows in the slip-flow regime. Pressure correction method with an appropriate slip boundary condition is an efficient tool in analyzing microscale flows. The present unstructured SIMPLE algorithm adopts both the classical Maxwell boundary condition and Langmuir boundary condition proposed by Myong. The simulation results of microchannel flows show that the proposed method has an effective predictive capability for microscale flows.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1225-1230
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• 2004

The effects of substrate material on the local heating performance of microheaters are studied by both numerical analysis and experiment. Transient conduction analysis shows that the substrate material with low thermal conductivity is critical to the local heating and fast response. A measurement technique for surface temperature field in microscale is newly proposed, which uses temperature sensitive fluorescent dye coated on the surface. The measured surface temperature fields on microheater arrays fabricated on different substrates are presented.