• Journal of Korean Society for Atmospheric Environment
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• v.18 no.1
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• pp.51-58
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• 2002

Destruction process of toluene using a wire-cylindrical BBD (Dielectric Barrier Discharge) reactor packed with catalysts was investigated to characterize the synergetic effects of non-thermal plasma and catalyst process. The catalysts used in the present study were ${\gamma}$-Al$_2$BO$_3$ and Pt/${\gamma}$-Al$_2$O$_3$. Under the numerous test conditions, specific energy density (SED (J/L)) and the conversion of toluene, defined as (1 -[C$_{f}$]/[C$_{i}$]), were measured. The test results showed that toluene decomposition efficiency followed the pseudo-first order in the case of plasma only process. The pseudo-first order process, however, was modified to pseudo-zeroth order reaction in the case of catalyst-assisted plasma process. This modification of the reaction order was verified based on a simple kinetic model proposed in the present study. Owing to the modification of reaction order, which resulted from the catalytic process, the specific energy to achieve the high removal efficiencies, i.e. 80~90%, was reduced significantly.y.y.

• Environmental Engineering Research
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• v.14 no.1
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• pp.32-40
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• 2009

In this study, we have prepared three kinds of carbon nanometer tube $CNT/TiO_{2}$ electrodes through impregnation with different concentration titanium n-butoxide (TNB) solution. The prepared electrodes were characterized with surface properties, structural crystallinity, elemental identification and photoelectrocatalytic activity. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine CNT. This indicated the blocking of micropores on the surface of CNT, which was further supported by observation via SEM. XRD results showed patterns for the composites and a typical single and clear anatase crystal structure. The main elements such as C, O and Ti were existed for all samples from the EDX data. The catalytic efficiency of the developed electrode was evaluated by the photoelectrodegradation of methylene blue (MB). The positive potential applied in photoelectrocatalytic (PEC) oxidation was studied. It was found that photoelectrocatalytic (PEC) decomposition of MB solution could be attributed to combination effects between $TiO_2$ photocatalytic and CNT electro-assisted. Through the comparison between photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation, it was found that the PEC oxidation efficiency for MB is higher than that of PC oxidation.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.165-172
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• 2008

Urea-SCR, the selective catalytic reduction using urea as reducing agent, has been investigated for about 10 years in detail and today is a well established technique for deNOx of stationary diesel engines. In the case of the SCR-catalyst a non-uniform velocity and $NH_3$ profile will cause an inhomogeneous conversion of the reducing agent $NH_3$, resulting in a local breakthrough of $NH_3$ or increasing NOx emissions. Therefore, this work investigates the effect of flow and $NH_3$ non-uniformities on the deNOx performance and $NH_3$ slip in a Urea-SCR exhaust system. From the results of this study, it is found that flow and $NH_3$ distribution within SCR monolith is strongly related with deNOx performance of SCR catalyst. It is also found that multi-hole injector shows better $NH_3$ uniformity at the face of SCR monolith face than one hole injector.

• Journal of the Korean Applied Science and Technology
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• v.22 no.1
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• pp.35-42
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• 2005

Aligned multi-wall carbon nanotubes (MWNTs) were synthesized through the catalytic decomposition of hydrocarbons in a quartz tube reactor. In this study, we investigated the influence of gas flow rate of feedstock on the structure and growth rate of vertically aligned carbon nanotubes produced by the floating catalyst method. As the flow rate of feedstock increased, the nanotube diameter became smaller and the length became longer. Although the growth rate also increased with the raise of flow rate, the optimum flow rate of feedstock existed for the crystallinity of carbon nanotubes.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.5
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• pp.48-56
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• 2009

The auto-ignition tests of hybrid rockets with the concentrated hydrogen peroxide as an oxidizer were presented. Auto-ignition was successfully demonstrated by injecting decomposed gases from $H_2O_2$ into paraffin or polyethylene fuels. In addition, restart and instant ignition were realized with this rocket. For stable combustion, a higher $L^*$ value was required for the paraffin combustion compared with PE. On the other hand, much faster response time was demonstrated in case of a paraffin, which was 13 and 30 ms at ignition delay and rise time respectively.

• Asian Journal of Atmospheric Environment
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• v.4 no.2
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• pp.63-71
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• 2010

The removal characteristics for aromatic and aliphatic VOCs by electron beam (EB) were discussed in terms of several removal variables such as initial VOC concentration, absorbed dose, background gas, moisture content, reactor material and inlet temperature. It was reviewed that only reactor material was an independent variable among the potential control factors concerned. It was also suggested that main mechanism by EB should be radical reaction for the VOC removal rather than that by primary electrons. It was discussed that the removal efficiency of benzene was lower than that of hexane due to a closed benzene ring. In the case of aromatic VOCs, it was observed that the decomposition of the VOCs with more functional groups attached on the benzene ring was much easier than those with less ones. As for aliphatic VOCs, it was also implied that the longer carbon chain was, the higher the removal efficiency became. An EB-catalyst hybrid system was discussed as an alternative way to remove VOCs more effectively than EB-only system due to much less by-products. This hybrid included supporting materials such as cordierite, Y-zeolite, and $\gamma$-alumina.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.452-454
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• 2012

본 논문에서는 열분해 및 촉매반응의 의한 Hydrazine의 Ammonia 전환율을 연구하였다. 원자력발전소 2차 계통은 물/증기 순환계통으로 기기 및 배관의 부식을 억제하고, 증기발생기(Steam Generator, SG)의 부식생성물 유입을 최소하기 위해 전휘발성처리법(All Volatile Treatment, AVT)을 적용하여 계통수의 pH를 약염기성으로 유지하고 있다. 또한 Hydrazine을 이용하여 계통수의 용존산소제거 및 환원성 분위기를 유지하고 있다. 현재 사용되는 AVT는 대부분 단일 아민(Ammine)으로 계통 전 영역에서 pHt를 약염기성으로 유지하기 어렵다. 따라서 복합 아민을 이용하여 단일 아민의 상호단점을 보완한 수처리법을 적용해야한다. 하지만 복합 아민을 적용할 경우 추가 아민 주입설비, 설치부지, 시설유지보수 및 관리가 요구되므로 기존 주입약품을 이용하여 아민을 공급할 수 있는 연구가 필요하다. 따라서 본 연구에서는 Hydrazine의 열분해 및 촉매반응을 이용한 Ammonia 전환율을 조사하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.499-502
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• 2009

The auto-ignition tests of hybrid rockets with the concentrated hydrogen peroxide as an oxidizer were presented. Auto-ignition, restartability, and instant ignition were successfully demonstrated by injecting decomposed gases from $H_2O_2$ into paraffin or polyethylene fuels. In addition, much faster response time was demonstrated in case of a paraffin, which was 13 and 30 ms at ignition delay and rise time respectively.

• Carbon letters
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• v.15 no.3
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• pp.198-202
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• 2014

Amorphous agglomerates of carbon nanospheres (CNS) with a diameter range of 10-50 nm were synthesized using the solution combustion method. High-resolution transmission electron microscopy (HRTEM) revealed a densely packed high surface area of $SP^2$-hybridized carbon; however, there were no crystalline structural components, as can be seen from the scanning electron microscopy, HRTEM, X-ray diffraction, Raman spectroscopy, and thermal gravimetric analyses. Electrochemical and thermo catalytic decomposition study results show that the material can be used as a potential electrode candidate for the fabrication of energy storage devices and also for the production of free hydrogen if such devices are used in a fluidized bed reactor loaded with the as-prepared CNS as the catalyst bed.

• Journal of Environmental Science International
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• v.13 no.1
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• pp.37-40
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• 2004

In this study, the decomposition of gas-phase TCE, Benzene and Toluene, in air streams by direct UV Photolysis and UV/TiO$_2$ process was studied. For direct UV Photolysis, by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene and Benzene in this work were determined to be 0.00392s$\^$-l/, 0.00230s$\^$-1/ and 0.00126s$\^$-1/, respectively. And the adsorption constant K of TCE, Toluene and Benzene in this work were determined to be 0.0519 mol$\^$-l/ ,0.0313mo1$\^$-1/ and 0.0084mo1$\^$-1/, respectively. For UV/TiO$_2$ system by regressing with computer calculation to the experimental results the value of reaction rate constant k of TCE, Toluene, and Benzene in this work were determined to be 5.74g/$\ell$$.$min, 3.85g/$\ell$$.$min, and 1.18g/$\ell$$.$min, respectively. And the catalyst adsorption constant K of TCE, Toluene, and Benzene in this work were determined to be 0.0005㎥/mg, 0.0043㎥/mg and 0.0048㎥/mg, respectively.