• Proceedings of the Membrane Society of Korea Conference
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• 1992.10a
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• pp.5-6
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• 1992

무기막은 고분자 계통의 유기막과는 달리 200$\circ$C 이상의 고온에서도 높은 기체 투과도와 구조적 안정성을 보인다. 따라서 무기막을 고온의 촉매 반응에 이용하면 생성물 중 일부를 선택적으로 분리시키므로써 열역학적으로 예측할 수 있는 값 이상의 높은 전환율을 얻을 수 있으며, 또한 반응물 중 일부를 막을 통해 주입하면 반응의 정도를 조절함으로써 원하는 생성물의 수율을 높일 수 있게 된다. 그러나, 현재 실험실에서 많이 연구되고 있는 다공성 유리 또는 다공성 알루미나와 같은 무기막들은 기체 투과도는 높은 반면에 기체 분리가 Knudsen diffusion에 의해 이루어지기 때문에 분리선택도가 낮은 단점이 있다.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.47.4-48
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• 2018

밀러-유리 실험은 1950년대 처음으로 초기 지구의 대기 방전 실험으로 아미노산을 합성한 실험이다. 생명의 기원에 대한 내용이 교과서나 책에 실릴 때마다 빠지지 않고 등장하는 실험으로, 학생들의 탐구 활동 연구주제로 실험을 설계하여 진행하였다. 실험실 설계부터 시작하여 실험 과정인 유리기구 세척, 진공 만들기, 기체주입과 방전실험을 소개한다. 실험 장치가 완성 된 후, 실험 시간 23시간 중 약 4시간 동안 방전하여 갈색 용액을 얻는데 성공하였다. 아민기와 반응하는 ninhydrin 반응에서 양성반응을 보여 아미노산 수용액임을 확인하였다.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.153-157
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• 2001

Operation conditions for the generation of an HF laser driven by fluorine-hydrogen combustion were discussed by mc:asuring the intensities of excited HF* molecules. Optimum injection quantities of fluorine gas for the generation of fluorine atoms was two times the injection mole number of hydrogen fuel. Slit nozzles with two dimensional configuration were used for the production of excited HF* molecules. When the injection mole number of secondary hydrogen gas is 1.3 times the injection mole number of fluorine gas, the fluorescence intensities of excited HF* molecules show maximum values. alues.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.111-118
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• 2013

The influence of gas flow on the plasma generation in the atmospheric plasma jet is described with the theory of hydrodynamics. The plasma discharge is affected by the gas-flow streams with Reynolds number (Re) as well as the gas pressure with Bernoulli's theorem according to the gas flow rate inserted into the glass tube. The length of plasma column is varied with the flow types such as the laminar flow of Re<2,000 and the turbulent flow of Re>4,000 as it has been known in a general fluid experiments. In the laminar flow, the plasma column length is increased as the increase of flow rate. Since the pressure in the glass tube becomes low as the increase of flow velocity by the Bernoulli's theorem, the breakdown voltage of plasma discharge is reduced by the Paschen's law. Therefore, the plasma length is increased as the increasing flow rate with the fixed operation voltage. In the transition of laminar and turbulent flows, the plasma length is decreased. When the flow becomes turbulent as the flow rate is increasing, the plasma length becomes short and the discharge is shut down ultimately. In the discharge of laminar flow, the diameter of plasma beam exposed on the substrate surface is kept less than the glass diameter, since the gas flow is kept to the distinct distance from the nozzle of glass tube.

• Clean Technology
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• v.7 no.4
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• pp.273-280
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• 2001

An absorber is a major component in the absorption refrigeration systems and its performance greatly affects the overall system performance. In this study, experimental analyses on heat transfer characteristics for removal of absorption heat in ammonia-water bubble mode absorber were performed. Heat transfer coefficients were estimated as the variations of input gas flow rate, solution flow rate, temperature, concentration, absorber diameter and height, and input flow direction. The increase of gas and solution flow rate affects positively in heat transfer. However, the increase of solution temperature and concentration affects negatively. Moreover, under the same Reynolds Numbers, countercurrent flow is superior to cocurrent flow in heat transfer performance. In addition, from these experimental data, empirical correlations which can explain easily the characteristics of heat transfer are derived.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.481-487
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• 2009

To control the diameter size of the carbon nanofilaments (CNFs), SF6 was incorporated in the source gases ($C_2H_2/H_2$) during the initial deposition stage. The source gases and $SF_6$ were manipulated as the cyclic on/off modulation of $C_2H_2/H_2/SF_6$ flow in a thermal chemical vapor deposition system. The characteristics of the CNFs formation on the substrate were investigated according to the different cyclic modulation processes and the substrate temperatures. By $SF_6\;+\;H_2$ flow injection during the cycling etching interval time, the diameter size of CNFs was extremely decreased. The cause for the decrease in the diameter size of the individual CNFs by the cyclic on/off modulation process of $C_2H_2/H_2/SF_6$ flow was discussed in association with the slightly enhanced etching ability by the incorporation of $SF_6$.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.403-410
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• 2009

Vacuum chambers have wide application for a variety of purposes such as material processing, vacuum gauge calibration, etc. As the dynamic pressure generated in such chamber is non-uniform, in many industrial as well as research processes, it is vital to know the non-uniform gas distribution with associated gas flow regimes and the ways of minimizing these pressure non-uniformities. In the present work, the behavior of gas flow in a vacuum chamber, during continuous gas flow, is described in the pressure range 0.1-133 Pa and the effect of baffle plate in minimizing the pressure non-uniformities is investigated. It was observed that maximum deviations in the pressure occur near the gas inlet point and that the effect of baffle plate in minimizing the pressure non-uniformities is more obvious in the transitional flow regime.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.654-658
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• 2012

In this study, $CO_2$ capture efficiency in relation to the inlet moisture content of the regenerator was investigated using potassium-based sorbents in the continuous process composed of two bubbling fluidized-bed reactors, where solid outlet configuration in the regenerator was converted from underflow to overflow. XRD (X-ray Diffraction), SEM (Scanning Electron Microscope) and TGA were performed to find out the effect of water pre-treatment according to inlet moisture content in the regenerator. The $K_2CO_3{\cdot}1.5H_2O$ structure of solid sorbents has been increased as inlet moisture content of the regenerator increased. As a result, the $CO_2$ capture efficiency increased as the $K_2CO_3{\cdot}1.5H_2O$ structure of solid sorbents increased since the reactivity of the sorbents has been improved by that structure generated by the water pre-treatment. And $CO_2$ capture efficiency increased about 3~8% after sorbent outlet configuration of the regenerator was changed underflow to overflow.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.40-40
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• 1999

가속기나 토카막과 같은 거대한 진공 장치의 용기 내벽을 청정화 하기 위해서는 용기 전체의 열처리(굽기, Baking)와 글로우 방전(Glow discharge) 법을 병행하여 사용한다. Baking은 일반 기체(N2, O2, 그리고 CO2)와 물(H2O)의 탈착에 효과적이고, Glow discharge cleaning은 탄소(Carbon-based)와 산소(Oxygen-based) 화합물의 탈착에 효과적이다. 특히 Glow discharge cleaning의 경우에는 전극의 모양, 진공 용기의 재질과 모양, 전극간의 거리, 사용되는 반응 기체의 압력 등에 따라 그 효과에 큰 차이가 있으므로 다각적인 연구가 필요하다. 본 연구에서는 그림 1과 같이 시험용 스테인레스(AISI 304와 AISI 316LN) 진공 용기를 설치하고, 시험 용기의 한쪽은 배기 용기와 oriffice로, 다른 편은 불순물의 정성.정량 분석을 위해 RGA(Residual gas analyser) 용기와 oriffice로 연결하였다. 전체 시스템 중에서 배기 부분과 분석 부분은 15$0^{\circ}C$에서 24시간 가열하여 전체의 기저 진공도를 1$\times$10-8Torr로 하였다. 기저 진공도의 용기에 고순도의 반응기체 (He, Ar, Ar+He, Ar+H2, Ar+N2 등)를 주입한후, DC 전압(0.8~1.5kV)을 변화하며 글로우 방전의 최적조건을 찾았다. 방전 동안 시험용 용기에서 방출되는 반응 기체 이외의 기체를 RGA로 측정하였고 외부에 Thermocouple을 여러곳에 장착하여 온도 변화를 측정하였다. 이상의 결과로부터 진공 용기 표면적으로부터의 불순물 탈착(desorption)과 불순물 분석, 플라즈마와 내벽의 상호작용등에 대한 결론을 얻을 수 있었다. 또한 Baking과 Glow discharge cleaning을 동시에 수행하여 Baking 온도의 낮춤에 따른 영향 평가도 수행하였다.

• Polymer(Korea)
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• v.28 no.3
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• pp.263-272
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• 2004

Using computer simulation, the processibility and properties of the inst겨ment panel of automobile produced by gas injection molding were predicted and evaluated. The P-V-T data of ABS, resin were used in the gas injection molding process in order to estimate the mold filling phenomena. The optimum process conditions were found by adjusting the process parameters including pressure, filling time, the positions of gas channel and runner. The process was simplified and the final instrument panel produced by the gas injection molding was found to have improved dimension stability compared to the one produced by conventional injection molding.