• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.77-80
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• 2001

Groundwater, contaminated predominantly with aromatic compounds and chlorinated ethylene, could be biologically treated in a fluidized-bed reactor with immobilized cells. The decomposition efficiency for the aromatics was over 90% at the retention time of 2.5 h. The chlorinated ethylenes, especially trichloroethylene (TCE) and cis-dichloroethylene (DCE), could be decomposed only insufficiently. No anaerobic methane formation was observed for this groundwater even at a very low dissolved oxygen (DO) concentration of 0.75 mg/L. The variation of DO concentration resulted in an optimal value of 1.5 mg/L. The recycle of air waste could increase the utilization of oxygen. The amount of low boiling pollutants stripped out remained constant with the recycle, while for the higher boiling pollutants the stripping slightly increased. Using air instead of oxygen increases the flow rate of air waste, which is connected to a higher stripping of pollutants. In this investigation, the pollutant concentration in the air waste remained constant. The stripping of main pollutants did not exceed 0.3 %.

• 한국연소학회지
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• 제3권1호
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• pp.11-19
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• 1998

The influence of oxidant addition on soot formation is investigated experimentally with ethylene, propane and mixture fuel co-flow diffusion flames. Oxidant addition into fuel shows the increase of integrated soot volume fractions for ethylene, ethylene/ethane and ethylene/methane mixture flames. However, the increase of integrated soot volume fraction with oxidant addition was not significant for propane and ethylene/propane mixture flames. This discrepancy is explained with $C_2\;and\;C_3$ chemistry at the early stage of soot formation process. The oxidant addition increases the concentration of $C_3H_3$ in the soot formation region, and therefore, enhances soot formation process. A new soot formation rate model that includes both dilution effect and chemical effect of oxygen is suggested to interpret the increase of integrated soot volume fractions with oxidant addition into ethylene. Also, the role of adiabatic flame temperature for the chemical effect of oxygen addition into fuel was reviewed. The influence of oxidant or diluent addition into fuel on soot formation process are the fuel dilution effect, the adiabatic flame temperature altering effect and/or the chemical effect of oxygen. Their relative importance could change with fuel structure and adiabatic flame temperature.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2002년도 제19회 학술발표대회 논문초록집
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• pp.18-18
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• 2002

A project where the TPUs(Turbo Pump Units) for 10tf-thrust oxygen/methane LRE (Liquid Rocket Engine) are under development is being implemented to include an experimental combustion chamber developed. In the process of it, we introduced the power-balanced engine cycles in order to substantiate concepts of the engine using the combinations of the propellants. Accordingly, the main engine parameters of nominal operating mode are resulted from the 1-Dcalculations and it is found that the regulators are needed for controlling the expected pressure levels in the characteristics of propellant mixture ratio and thrust supposing the regulator is set to analogue-typed one which is easy to develop.The technical requirements like the nominal flow rate, its deviations expected and the pressure difference In need helped the several main characteristics of regulators to be determine in this stage. Here, a dozen of deviation values in the main parameters related to engineoperation are taken into independent consideration and accepted to the results for additional regimes of the regulators.Finally, we can determine the scheme and the primary dimensions along with the calculation design of the spring acceptable for general configuration which can definitely forwarded to the autonomous tests of the aggregates, The obtained data in further will be used for successive refinement of operating mode of the engine.

• 한국화재소방학회논문지
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• 제24권2호
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• pp.139-144
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• 2010

본 연구에서는 산업용으로 일반적으로 사용하고 있는 질소발생기를 사용하여 할론 계열의 소화약제를 대체할 청정소화설비로 적용할 수 있는지에 대한 소화성능 실험을 간단히 수행하였다. 산업용 질소발생기의 소화성능을 분석하기 위하여 간단한 방호구역을 제작하여 실제 질소발생기에서 발생하는 질소가스를방사하면서 방호구역 내의 산소농도 변화를 실험적으로 파악하였다. 실험결과, 현재 많이 사용하고 있는 질소발생기로 방호구역 $100m^3$에 대하여 질소가스를 $5m^3$/min로 방사하면 3분 이내에 방호구역 내의 산소 농도를 15% 이내로 낮추어 질식소화가 충분히 가능하다.

• 한국재료학회지
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• 제23권1호
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• pp.1-6
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• 2013

A simple thermal oxidation of Cu thin films deposited on planar substrates established a growth of vertically aligned copper oxide (CuO) nanorods. DC sputter-deposited Cu thin films with various thicknesses were oxidized in environments of various oxygen partial pressures to control the kinetics of oxidation. This is a method to synthesize vertically aligned CuO nanorods in a relatively shorter time and at a lower cost than those of other methods such as the popular hydrothermal synthesis. Also, this is a method that does not require a catalyst to synthesize CuO nanorods. The grown CuO nanorods had diameters of ~100 nm and lengths of $1{\sim}25{\mu}m$. We examined the morphology of the synthesized CuO nanorods as a function of the thickness of the Cu films, the gas environment, the oxidation time, the oxidation temperature, the oxygen gas flow rate, etc. The parameters all influence the kinetics of the oxidation, and consequently, the volume expansion in the films. Patterned growth was also carried out to confirm the hypothesis of the CuO nanorod protrusion and growth mechanism. It was found that the compressive stress built up in the Cu film while oxygen molecules incorporated into the film drove CuO nanorods out of the film.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권3호
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• pp.77-80
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• 2003

An innovative ozonizer has been developed using a high frequency, surface discharge and a high purity Ti-Si-AI ceramic catalyst as a dielectric component. Using a type of thin film, a thin cylindrical compound ceramic catalyst layer was adhered to the outside surface of its inner electrode. An alternating current (AC) exciting voltage with frequencies from 0.6 KHz to 1.0 KHz and peak-to-peak voltages of 4-6 ㎸ was applied between the electrodes to produce a stable high-frequency silent discharge. A substantial reduction of the exciting voltage was also enabled by means of a thin Ti-Si-Al ceramic catalyst tube. As a result, the ozonizer can effortlessly obtain the required ozone concentration (50-60 g/$m^2$ for oxygen) and high ozone efficiency consumption power (180 g/kWh for oxygen) with-out the assistance of any particular methods. For purposes of this experiment, oxygen gas temperature was set at 2$0^{\circ}C$, with an inner reactor pressure of 1.6 atm at 600 Hz and a flow rate of 2 l/min.

• 한국응용과학기술학회지
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• 제31권3호
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• pp.446-452
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• 2014

Methanol was directly produced by the partial oxidation of methane with four-component mixed oxide catalysts. Four-component(Mo-Bi-Cr-Si) mixed oxide catalysts were prepared by the co-precipitation and sol-gel methods. The catalyst prepared by the sol-gel method showed about eleven times higher surface area than that prepared by the co-precipitation method. From the $O_2$-TPD experiment of the prepared catalysts, it was proven that there exists two types of oxygen species, and the oxygen species that participates in the partial oxidation reaction is the lattice oxygen desorbing around $750^{\circ}C$. The optimum reaction condition for methanol production was $420^{\circ}C$, 50 bar, flow rate of 115 mL/min, and $CH_4/O_2$ ratio of 10/1.5, providing methane conversion and methanol selectivity of 3.2 and 26.7%, respectively.

• Journal of Chest Surgery
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• 제36권7호
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• pp.472-482
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• 2003

심폐바이패스의 재가온 시기 동안 뇌산소 탈포화가 수술 후 신경학적 합병증 발생의 원인 중 한가지라고 보고된 바 있다. 따라서 심폐바이패스 동안 뇌산소 탈포화를 예방해 줌으로써 수술 후 신경학적 합병증 발생을 줄일 수 있으리라 생각된다. 본 연구는 심폐바이패스 동안 뇌산소 탈포화를 예방해주는 방법인 고탄산분압과 고관류가 뇌대사에 미치는 영향을 비교하기 위해 실시되었다. 대상 및 방법: 심장수술을 시행할 36명의 성인 환자들을 대상으로 심폐바이패스의 재가온 시기 동안 동맥혈액의 고탄산분압군(Pa$CO_2$ 45~50mmHg, n＝18)과 고관류군(2.75 L/ $m^2$/min, n＝18)으로 나누었다. 전체 환자들에 대해 중대뇌동맥 혈류 속도, 뇌동정맥혈 산소함량 차이, 뇌산소 대사율, 뇌산소 운반율, S-100 $\beta$ 농도 증가율, 뇌정맥혈 산소 탈포화도 등을 심폐바이패스 전, 심페바이패스 실시 10분, 재가온-1기(비인두 온도: 33$^{\circ}C$), 재가온-2기(비인두 온도; 37$^{\circ}C$), 심폐바이패스 종료 직후 등의 다섯 시기에 측정하였다. 그리고 수술 후 섬망 발생률과 지속시간 역시 조사하여서 위의 모든 변수들과 함께 양 그룹간에 비교하였다. 결과: 고탄산분압군이 고관류군 보다 재가온 시기 동안 중대뇌동맥 혈류 속도(157.88$\pm$10.87 vs 120.00$\pm$6.18%, p＝0.006), 뇌정맥혈 산소분압(41.01$\pm$2.25 vs 32.02$\pm$1.67 mmHg, p＝0.03) 및 포화도(68.01$\pm$2.75 vs 61.28$\pm$2.87%, p＝0.03), 뇌산소 운반비율(110.84$\pm$7.41 vs 81.15$\pm$8.11%, p＝0.003)이 유의하게 더 높았다. 재가온 동안 뇌동정맥 산소함량 차이(4.0$\pm$0.30 vs 4.84$\pm$0.38mg/dL, p＝0.04), S-100 $\beta$ 증가율(391.67$\pm$23.40 vs 940.0$\pm$17.02%, p＝0.003), 뇌정맥혈 산소 탈포화도(2명 vs 4명, p＝0.04), 수술 후 섬망증의 지속시간(18 vs 34 hr, p＝0.02)은 고탄산분압군이 고관류군에 비해 상대적으로 낮았다. 결론: 상기한 결과들을 비교 분석한 바 심폐바이패스 시 고탄산분안법이 고관류법 보다 뇌조직에 산소공급을 더 많이 해줌으로써 뇌대사가 상대적으로 원활하여 신경학적 합병증 발생률이 낮은 것으로 사료된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.255-255
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• 2011

Zinc oxide based thin films have been extensively studied in recent several years because they have very interesting properties and zinc oxide is non-poisonous, abundant and cheap material. ZnO films are employed in different applications like transparent conductive layers in solar cells, protective coatings and so on. Wide industrial application of the ZnO films requires of development of cheap, effective and scalable technology. Typically used technologies don't completely satisfy the industrial requirements. In the present work, we studied effect of the deposition parameters on the structure and properties of ZnO films deposited by DC arc plasmatron. The varied parameters were gas flow rates, precursor composition, substrate temperature and post-deposition annealing temperature. Vapor of Zinc acetylacetone was used as source materials, oxygen was used as working gas and argon was used as the cathode protective gas and a transport gas for the vapor. The plasmatron power was varied in the range of 700-1500 watts. Flow rate of the gases and substrate temperature rate were varied in the wide range to optimize the properties of the deposited coatings. After deposition films were annealed in the hydrogen atmosphere in the wide range of temperatures. Structure of coatings was investigated using XRD and SEM. Chemical composition was analyzed using x-ray photoelectron spectroscopy. Sheet conductivity was measured by 4-point probe method. Optical properties of the transparent ZnO-based coatings were studied by the spectroscopy. It was shown that deposition by a DC Arc plasmatron can be used for low-cost production of zinc oxide films with good optical and electrical properties. Increasing of the oxygen content in the gas mixture during deposition allow to obtain high-resistive protective and insulation coatings with high adhesion to the metallic surface.

• 항공우주기술
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• 제10권1호
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• pp.54-62
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• 2011

추진제탱크 가압가스 요구량 예측을 위해 개발된 수치해석 모델을 사용하여 운용조건에 따른 가압가스 요구량 변화를 살펴보았다. 한국형발사체 1단 산화제탱크의 개념설계 결과를 기준 모델로 정하였고, 산화제탱크로 유입되는 가압가스의 온도, 산화제의 체적유량, 산화제탱크 길이 대 직경의 비를 운용 변수로 선정하였다. 가압가스 요구량 및 질량유량, collapse factor, 얼리지 온도분포를 예측하였고, 그 결과 가압가스의 온도가 가압가스 요구량에 가장 큰 영향을 미침을 확인하였다. 또한 얼리지에 대한 에너지 분석을 통하여 추진제탱크의 가압효율을 계산하였고, 유입된 가압가스 에너지 중 추진제탱크 벽면을 통한 열손실이 가장 큼을 확인하였다.