• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1548-1549
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• 2006

모세관 방전은 내벽의 절연 물질이 용발되어 수만도 영역에서 고압의 플라즈마를 생성하는 장치로서 이로부터 분사된 플라즈마 제트는 추진제 점화나 신물질 제조 둥에 이용할 수 있다. 본 연구에서는 수십 $m{\Omega}$ 영역에서 수 ms에 걸쳐 수십 kA의 펄스 전류가 흐르는 모세관 방전에 대해 플라즈마의 온도 및 압력에 의해 결정되는 저항을 통하여 펄스 전원 회로를 해석하며, 이로부터 공급되는 오옴열에 의해 플라즈마의 온도, 압력 등이 결정되는 유체역학적 변화를 수치적으로 계산하였다. 이 결과는 용발에 의해 정상 상태에 도달하는 플라즈마의 특성을 잘 보여주고 있으며, 모세관 방전 실험의 전기적, 유체역학적 변수 예측에 유용하게 쓰일 수 있다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1091-1097
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• 2013

In this article, an advanced cooling surface based on micro-post arrays with non-homogeneous configurations is investigated and compared with conventional micro-post arrays with homogeneous configuration. The capillary performance of micro-post arrays are characterized using the capillary rate of rise experiments and numerical simulations which take into account the meniscus curvature. The experimental and numerical results show that that the capillary performance of the micro-post wick can be significantly enhanced, compared with the homogeneous type wick, by employing non-homogeneous configurations. The capillary performance is shown to be primarily a function of the solid fraction and increases linearly with decreasing solid fraction, regardless of the wick configuration, when the solid fraction is larger than 0.25. However, the capillary performance is found to be significantly reduced when the solid fraction falls below approximately 0.25.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.383-389
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• 2016

Based on a surface design with rectangular cavities and channels, we investigated the effects of gravity and capillary pressure on pool-boiling Critical Heat Flux (CHF). The microcavity structures could prevent liquid flow by the capillary pressure effect. In addition, the microchannel structures contributed to induce one-dimensional liquid flow on the boiling surface. The relationship between the CHF and capillary flow was clearly established. The driving potentials for the liquid supply into a boiling surface can be generated by the gravitational head and capillary pressure. Through an analysis of pool boiling and visualization data, we reveal that the liquid supplement to maintain the nucleate boiling condition on a boiling surface is closely related to the gravitational pressure head and capillary pressure effect.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.233.1-233.1
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• 2005

• Korean Journal of Optics and Photonics
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• v.3 no.2
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• pp.137-140
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• 1992

레이저 플라즈마에서 방출되는 X-선의 이용이 크게 발전될 것이 예측되나, X-선에 대한 광속의 시준화, beam homogenizing, 광속축소, 광유도 등이 어려워서 예상한 바 큰 발전이 이루어지지 못하고 있다. 이 난제를 해결할 수 있는 가능성이 모세관 광유도광학에서 엿보이기에 여기에 소개하여 광학, 레이저 플라즈마 등을 연구하는 회원들의 관심을 끌고자 한다.

• Membrane Journal
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• v.28 no.3
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• pp.214-219
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• 2018

In the present study, superflux nickel capillary supports for gas and vapor separation membranes were prepared by a combined process of NIPS and sintering. Nickel capillary precursors were prepared by NIPS process from PSf-Ni-DMAC-PEG400 dope solution and was sintered at various temperatures in $H_2$ atmosphere to reliably produce Ni capillary support. The optimized Ni capillary support has an outer and inner diameters of 722 and $550{\mu}m$, and its thickness was $94{\mu}m$. It has 3-dimensional pore channel network and its porosity and mean pore diameter was 26% and $4{\mu}m$, respectively. Also, its mechanical strength was tested in tensile mode: its fracture load was 2.84 kgf and the fracture elongation was 13%. Finally, its single gas permeance was measured: He, $N_2$, $O_2$, and $CO_2$ permeance was 432,327, 281,119, 264,259, and 193,143 GPU, respectively. The superflux behavior could be explained from viscous flow through the macropores having a diameter of $4{\mu}m$ and narrow thickness. It could be concluded that the superflux behavior of the Ni capillary support was from the 3-D pore channel network and the small thickness.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2131-2133
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• 2004

모세관 전기영동 및 전기화학적 검출 시스템을 마이크로 시스템에 적용하여 ITO 유리기판과 polydimethylsiloxane (PDMS)로 제작하였다. 제작된 모세관 전기영동 및 전기화학적 검출 시스템은 일회용으로 사용가능하며 전기화학적 검출에 아주 적합한 특성을 보인다. 모세관 전기영동 및 전기화학적 검출 시스템은 주입과 분리 채널 (80 ${\mu}m$ 폭 ${\sim}$ 40 ${\mu}m$ 깊이)을 가진 PDMS 층과 유리기판 위에 검출 전극으로 사용되는 ITO가 형성된 층으로 구성된다. PDMS 층과 ITO 유리 기판은 UV-$O_3$ cleaner를 사용하여 접합하였다. 완충용액은 10 mM 2-(N-morpholino)ethanesulfonic acid (MES)를 사용하였고 분석물질은 1 mM 농도의 dopamine과 1 mM 농도의 catechol을 사용하였다. 60 V/cm 전계로 주입 및 분리를 하였으며 작업전극과 기준전극 간의 전위는 +600 mV로 유지하며 분석물질의 농도에 비례하는 전류량법으로 측정하였다. 전기화학적 검출 회로는 천기영동 전계의 간섭으로부터 분리하였다. 10 mM MES 완충용액에서 바탕 전류의 크기가 ${\sim}$10 pA 일 때 측정전류 값은 10 nA이다. 측정된 피크 값은 기존의 Au 전극과 비교하여 선택성, 감도, 분해능이 유사한 특성을 보여준다.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1998.05a
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• pp.128-130
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• 1998

지난날 각 가정에 많이 사용해왔던 등잔불이 심지라는 섬유제품을 통하여 기름이 올라오는 원리 즉 모세관 현상을 이용한 조명 방법이었다. 고형배지를 이용한 양액재배에서 양액의 공급은 동력기기를 이용한 소위 에너지를 많이 소비하는 방법이 거의 전부라 할 수 있다. 에너지를 절약할수 있는 방법을 생각하던 중에 섬유직조물들이 갖고 있는 모세관현상을 이용한 급액방법을 몇가지 섬유제품을 가지고 시도해 보았는데 예상했던 것 보다 훨씬 다양하고 좋은 결과를 얻었다. (중략)

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.16-25
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• 2004

Theoretical analysis for predicting the heat transport limitation of a copper powder sintered wick heat pipe was performed. The heat pipe diameter was 8mm and water was used for working fluid. The particle diameter was classified by 5 different meshes, and each capillary pressures and heat transport limitations. thermal resistances were analyzed according to the operating temperatures, wick thicknesses and inclination angles, based on the effective capillary radius($r_c$), porosity($\varepsilon$), Permeability (K). The wick capillary limitation was increased according as the particle diameter and the wick thickness and the operating temperature were increased. As the porosity and the capillary radius were larger. then the heat transport limitation was higher. The thermal resistance was greatly increased according as the wick thickness was increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6452-6457
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• 2014

R1234yf has been developed as an alternative refrigerant to R134a, which has been associated with global warming. The capillary tubes as expansion valves control the mass flow rate and balance system pressure in the refrigeration cycle. The present numerical model used the governing equations including the law of conservation of mass, momentum, and energy in a capillary tube. The mass flow rate of R1234yf decreased by 47.0% as the capillary tube length was increased from 1 to 4 m. As the inner diameter of the capillary tubes was changed from 1.3 to 1.7 mm, the mass flow rate of R134a and R1234yf increased by 117.9% and 121.0%, respectively. The mass flow rate of the R134a and R1234yf increased by 28.3% and 29.1% with subcooling increasing from 0 to $7^{\circ}C$. In addition, when the inlet temperature of the capillary tubes was changed from 35 to $60^{\circ}C$, the mass flow rate of R134a and R1234yf increased by 31.0% and 45.4%, respectively.