• 센서학회지
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• 제28권4호
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• pp.225-230
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• 2019

$Au@TiO_2$ core-shell decorated rGO nanocomposite (NC) was prepared using a simple solvothermal method followed by heat treatment for gas sensor application. The crystal structure and morphology of the composites were characterized by X-ray powder diffraction and transmission electron microscopy, respectively. The $NO_2$ sensing response of the $Au@TiO_2/rGO$ NC was tested at operating temperatures from $250^{\circ}C$ to $500^{\circ}C$, and was compared with those of the bare rGO and $Au@TiO_2$ core-shell NPs. The $Au@TiO_2/rGO$ NC-based sensor showed a far higher response than the rGO or $Au@TiO_2$ core-shell based sensors, with the maximum response detected when the operating temperature was $400^{\circ}C$. This improved response was due to the high rGO gas absorption capability for $NO_2$ gas and the catalytic effect of $Au@TiO_2$ core-shell NPs in oxidizing $NO_2$ to $NO_3$.

• 한국추진공학회지
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• 제26권1호
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• pp.12-19
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• 2022

덕티드 로켓의 가스발생기에 사용되는 추진제는 연료과농 추진제로서, 일반적인 고체 로켓 추진제에 비하여 과량의 금속연료와 소량의 산화제를 포함한다. 본 논문에서는 연료과농 추진제를 제조하기 위하여 보론 분말과 MgAl(Magnesium-Aluminium Alloy)를 적용하였다. 이 금속연료를 적용한 추진제의 특성을 분석하였고, 이를 통하여 최적의 조성을 연구하였다. 추진제의 연소생성물 분석을 통하여 보론 비드가 아닌 미립의 보론 분말로도 가스발생기용 연료과농 추진제가 가능함을 확인하였다.

• 방사성폐기물학회지
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• 제7권4호
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• pp.207-212
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• 2009

본 연구에서는 산화조건하 LiCl-KCl 공융염내에서 란탄계 염화물의 하나인 $PrCl_3$의 열적거동을 살펴보았다. 먼저 산소를 주입하면서 $PrCl_3$의 열중량분석(TGA; thermogravimetric analysis)을 실시하였고, 이 때 얻어진 결과들을 바탕으로, 산소분산법을 이용하여 온도에 따른 LiCl-KCl 공융염내 $PrCl_3$의 산화실험을 수행하였다. $PrCl_3$의 열중량분석 결과에 따르면, 약 $380^{\circ}C$까지 $PrCl_3$에서 염소의 해 리가 급격하게 발생되었고 약 $600^{\circ}C$에서 $PrCl_3$가 PrOCl로 전환되는 반응이 종료되는 것으로 확인되었다. 산소분산법에 의한 LiCl-KCl 공융염내 $PrCl_3$의 열적거동은 산화조건에서 열중량분석시 나타난 $PrCl_3$의 열적거동과 유사하였고, 발생된 PrOCl은 공융염내에서 불용성 화합물로써 바닥으로 침전하였다. 산소분산법에 의한 공융염내 $PrCl_3$의 PrOCl로의 전환은 $650^{\circ}C$ 이상의 온도에서 활발하게 진행되었고, 이 때 발생되는 배기가스내 $Cl_2$의 농도분석을 통해 공융염내 $PrCl_3$의 전환상태를 예측할 수 있을 것으로 판단된다.

• 청정기술
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• 제18권2호
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• pp.209-215
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• 2012

분말활성탄과 제올라이트가 담지된 폴리우레탄 담체를 충진한 파일롯 규모의 바이오필터를 이용하여 암모니아와 황화수소의 처리 성능을 평가하였다. 약 10개월간 하수처리장 슬러지 농축조에서 발생하는 악취를 대상으로 바이오필터 유입 암모니아 농도는 0.1~1.5 $ppm_v$, 황화수소 농도는 2~20 $ppm_v$ 범위에서 운전되었다. 바이오필터의 공탑체류시간 3.6~5초 범위에서 초기 순응기간을 제외하고는 거의 모든 경우 100%에 가까운 악취 제거율을 보여주었다. 바이오필터에서의 기체흐름에 의한 압력손실도 매우 낮아 10개월 동안 최대 31 mm $H_2O$ 정도의 차압이 발생하였다. 이것은 본 연구에 이용된 바이오필터의 막힘이나 담체의 압착 현상이 거의 일어나지 않아 장기간의 운전에도 안정성을 확인할 수 있었다. 담체에 부착하여 서식하는 미생물군집은 바이오필터의 처리 성능에 중요한 영향을 미치는데 특히 암모니아나 황화수소를 제거하기 위한 암모니아 산화균과 황산화균의 분포가 중요하다. FISH (Fluorescence in Situ Hybridization) 방법으로 확인한 결과 질산화를 주관하는 암모니아 산화균인 Nitrosomonas sp.와 황산화균인 Thiobacillus ferroxidans가 검출되었다. 또한 바이오필터의 운전기간이 길어질수록, 그리고 악취의 유입부분이 유출부분에 비해 미생물 분포량이 더 많음을 확인하였다.

• 한국대기환경학회지
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• 제14권4호
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• pp.313-320
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• 1998

The most desirable diesel oxidation catalyst (DOC) should have the properties of oxidibing CO and HC effectively at low exhaust gas temperature while minimizing the formation of sulfate at high exhaust gas temperature. Precious metals such as platinum and palladium have been known to be sufficiently active for oxidizing CO and HC and also to have high activity for the oxidation of sulfur dioxide (SO2) to sulfor trioxide (SO3). There is a need to develop a highly selective catalyst which can promote the oxidation of CO and HC efficiently, but, on the other hand, suppress the oxidation of SO2. One approach to solve this problem is to load a base metal such as vanadium in Pt-based catalyst to suppress sulfate formation. In this study, a Pt-V catalyst was prepared by impregnating platinum and vanadium onto a Ti-Si wash coated catalyst in a laboratory reactor by changing the formulations and reaction temperatures.

• 한국연소학회지
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• 제8권1호
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• pp.9-16
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• 2003

Carbon soot emission from combustion processes, especially from diesel engines, is a subject of growing concern since soot is known to seriously affect human health. Efforts have been made to oxidize soot particles utilizing Non-Thermal Plasma(NTP) techniques. When oxygen is carried into a plasma device, electrons generated by the plasma dissociate the oxygen, resulting in the formation of oxygen atoms. These highly activated atoms, called O radicals, are known as strong oxidizing agent. This paper presents concentration variations of CO and $CO_2$ at the exit of the plasma device, resulting from the soot oxidation by O radicals, with variations of inlet oxygen concentration, gas temperature, and gas flow rate. Based on the data, Arrehenious rate constants of reactions between C(s)+O and C(s)+O+O were proposed.

• Transactions on Electrical and Electronic Materials
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• 제5권4호
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• pp.161-165
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• 2004

In order to get oxidizing power enough for growth of a superconductive thin film with oxide gas, concentrated ozone was used. As a method for concentrating ozone, a method for concentrating ozone by adsorbing ozone selectively into silica-gel beads is adopted, and this concentration is analyzed by the ultraviolet absorption method, the thermal decomposition method and the Q-mass analyzing method. Thermal decomposition method is most effective for measurement of a high concentration of ozone. Ozone as concentrated by the adsorption method got to have a concentration of 97 mol % at the maximum, and it was identified that the concentration of the ozone gas was stable for the time while a thin film was formed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1192-1195
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• 2003

A highly condensed ozone gas be transferred to the superconductor thin film growth chamber because ozone is strong oxidizing gas. In order to obtain high quality oxide thin films, higher ozone concentration is necessary. In this paper an ozone condensation system was evaluated from the viewpoint of an ozone supplier for oxide thin film growth. Ozone was condensed by an adsorption method and the ozone concentration reached 8.5 mol% in 2.5 h after the beginning of the ozone condensation process, indicating high effectiveness of the condensation process. Ozone was continuously desorbed from the silica gel by the negative pressure.

• Carbon letters
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• 제2권1호
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• pp.55-60
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• 2001

Graphite intercalation compounds (GIC) were prepared by direct reaction of $SO_3$ gas with flake graphite. The intercalated $SO_3$ molecules were ejected by rapid heating to $950^{\circ}C$ under an oxidizing atmosphere for about 1 minute, resulting in surprisingly high expansion in the direction of c-axis. The characteristics of the micro-structure and pore size distribution were examined with a SEM and mercury intrusion porosimetry. The XRD analysis and spectroscopic analysis were used for the identification of the graphite and surface chemistry state. The pore size distribution of the exfoliated graphite (EG) was a range of $1{\sim}170{\mu}m$. The higher expanding temperature the higher expanded volume, so oil sorption capacities were 58.8 g of bunker-C oil and 34.7 g of diesel oil per 1 g of the the EG. The sorption equilibrium was achieved very rapidly within several minutes. As the treatment temperature increases, bulk density decreases.

• 오토저널
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• 제4권1호
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• pp.46-55
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• 1982

When an oxidizing catalytic converter which makes use of platium as a catalyst is employed by means if emission control of CO and HC gasoline engine, the effects of important factors for the purification efficiency, i.e engine speed and secondary air rate, on the reduction of CO and HC concentrations in the exhaust gas are studied experimentally. In the experiment, gasoline and LPG are used as a fuel, and the purification efficiency is examined and the results of both cases are compared with each other. The experimental results showed that the purification efficiency in the case of LPG is usually higher than that of gasoline, and the optimum values of engin speed and secondary air rate for maximum purification efficiency exist in common on both cases.