• Proceedings of the Korean Vacuum Society Conference
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• 2005.02a
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• pp.79-79
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• 2005

• Proceedings of the Korean Vacuum Society Conference
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• 1997.07a
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• pp.225-226
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• 1997

• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.178-184
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• 2012

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases and $SF_6$ as an additive gas under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils were investigated as functions of additive gas flow rate and the cycling on/off modulation of $C_2H_2/SF_6$ flows. Even in the lowest $SF_6$ flow rate (5 sccm) in this work, the cycling on/off modulation injection of $SF_6$ flow for 2 minutes could give rise to the formation of nanosized carbon coils, whereas the continuous injection of $SF_6$ flow for 5 minutes could not give rise to the carbon coils formation. With increasing $SF_6$ flow rates from 5 to 30 sccm, the cycling on/off modulation injection of $SF_6$ flow confines the geometry for the carbon coils to the nanosized ones. Fluorine's role of $SF_6$ during the reaction was regarded as the main cause for the confinement of carbon coils geometries to the nano-sized ones.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.42-42
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• 2003

Ni/Si 기판상에 CH$_4$, H$_2$, $N_2$의 혼합기체를 사용하여 $700^{\circ}C$에서 5분 동안 MPECVD법으로 탄소나노튜브 성장시켰다. 이 과정에서 CH$_4$, H$_2$에 대한 $N_2$의 유량비를 여러 가지 값으로 변화시켜 그 성장 양상을 살펴보았다. 혼합기체 내 질소의 함량에 따라 나노튜브의 성장길이와 quality가 달라짐을 SEM과 Raman spectroscopy 측정을 통하여 확인하였다. 나노튜브의 성장 시 혼합기체 내 주입하는 질소량에 의해 나노튜브의 성장길이가 변화됨을 SEM을 통해 관찰할 수 있었고 혼합기체 내 질소의 비율이 커질수록 carbonaceous particle 등의 감소로 인한 나노 튜브의 quality가 향상됨을 Raman spectra를 통해 확인할 수 있었다. 또한 TEM과 SEM 관찰을 통해 성장된 탄소나노튜브가 대나무(bamboo) 구조를 가진 수직 배향된 다중벽 탄소나노튜브임을 확인하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.236-236
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• 1999

AC-PDP(Plasma display Panel)는 기체 방전을 이용한 디스플레이로서 기체에 직접 노출되는 MgO 보호막의 이차전자 방출계수(${\gamma}$)는 AC-PDP의 방전특성을 결정짓는 중요한 요소이다. MgO 보호막의 이차전자 방출계수는 AC-PDP에 주입하는 기체의 종류, 결정 방향성과 표면오염상태등에 영향을 받는다. 본 연구에서는 MgO 보호막을 열처리한 상태와 열처리 하지 않은 상태를 ${\gamma}$-FIB 장치를 이용하여 2차전자방출 계수를 측정하여 비교하였다. 또한 24시간 MgO 보호막을 대기중에 방치하여 두었을 때 MgO 보호막의 표면오염상태에 대한 2차전자방출계수값을 측정하여 MgO 보호막의 표면오염에 대한 방전 전압특성저하가 어느정도인지를 알아보았다. 실험에 사용한 혼합기체는 Ne+Xe, He+Ne+Xe 혼합기체를 사용하였고, MgO 보호막은 21inch 규격의 실제 PDP Panel의 MgO 보호막을 사용하였다.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.162-167
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• 1992

Tic and TiN layers were deposited on the stainless steel substrate by the reactive RF sputtering. Ar was used for sputtering gas and CzHz and Nz were used for reaction gas. Deposition rate increased linearly to the applied RF power, and decreased as the partial pressure ratio of sputter gas to reactive gas increased. The thin layers were stoichiometric at the partial pressure ratio of 0.03 for Tic and at partial pressure ratio of 0.05 for TiN. The morphologies and structures of the thin layers were investigated by AES, SEM and TEM. In addition, N+ ion was implanted to Tic and the resulting influence on the film and annealing effects were also examined.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.707-712
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• 1996

중대사고시 원자로 압력용기내 또는 원자로 공동(cavity) 내에서의 노심용융물은 주입되는 물로 인하여 물과 접촉하는 표면이 냉각되면서 피막층(crust)이 형성된다. 이러한 피막층의 형성은 노심용융물과 냉각수 사이의 열전달 현상에 영향을 미치며 중대사고 발생시 사고 진행에 중요한 역할을 한다. 본 연구에서는 이러한 용융물의 피막층 형성의 해석모델을 수립하기 위해 전이현상과 전도와 대류를 포함하는 2차원 열전달과 상변화를 수반하는 문제를 포함하는 운동량방정식과 에너지방정식을 2차원으로 구성하였으며 에너지방정식은 엔탈피의 함수로 나타내었다. 그리고 이러한 2차원 지배방정식을 해석하기 위해 유한차분법 및 SIMPIER 알고리즘을 이용하였다. 비교대상으로는 한국원자력연구소에서 수행한 냉각수의 비등과 기체주입 효과가 고려되지 않은 실험을 대상으로 하였다. 계산결과 용융물의 피막층은 파동(wave) 형태로 형성되었으며 일정시간이 경과하면 변화가 없는 안정한 상태가 되었다. 용융물 내에서의 온도분포는 액체상태일 경우에는 하부가열면과 상변화가 일어나는 경계면부근을 제외하고는 거의 일정한 온도분포를 나타내고 있으며 용융물이 고화된 피막층에서는 급격한 온도변화를 보여주고 있다.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.869-874
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• 2003

The atomization characteristics were investigated through the influence of the change of GLR and the change of working fluid on droplet size distribution and mean diameter of drop produced by effervescent atomizer. For simultaneous injection of water and high viscous waste vegetable oil, effervescent atomizer with two aerator tubes was specially designed. From the experimental results, regardless of mass fraction of vegetable oil in working fluids, it is expected that effervescent atomizer will exhibit excellent atomization performance at the high GLR conditions.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1316-1321
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• 2004

An experimental study is performed on atomization characteristics and stable operating condition for injection of high viscous waste vegetable oil using effervescent atomizer with two aerator tubes. Consideration is given to the effects of ALR and liquid viscosity on the velocity and mean diameter of the injected droplet. It is found that (i) as ALR increases, the axial velocity of the droplet is increased, while half-velocity width and SMD are decreased regardless of the change in liquid viscosities, (ii) the rate of fine drop distribution occupied in the total spray field is increased with an increasing in ALR, and (iii) the effect of viscosity on atomization characteristics is minor.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.121-128
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• 1998

In fields of operating or handling a hydrogen isotope facility, and of the technology for nuclear fusion source management, gas chromatography has been used as one of the practical techniques lot separation and enrichment of hydrogen isotopic gases including tritium. Chromatographic separation experiments of the hydrogen isotope mixture (hydrogen, deuterium and tritium) were carried out by use of a commercially available gas chromatograph. An aliquot of gas sample was injected by a specially designed vacuum sampler into the stream of inert carrier gas which went through the separation column under liquid nitrogen temperature. The complete separation of hydrogen isotopic molecules was observed with an alumina adsorbent partially deactivated by coating with 10% manganese chlorine. In addition, fairly good separation conditions were obtained without any appearance of nuclear spin isomers with shorter retention time, which would be available for the practical applications of the hydrogen isotope separation and enrichment.