• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.937-945
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• 1999

In an effort to protect a RBSC(reaction -bonded SiC) tube SiC films from methyltrichlorosilane(MTS) by low pressure chemical vapor deposition were deposited in hydrogen atmosphere on the RBSC(reaction-bonded SiC) substrates over a range of input gas ratio(${\alpha}=P_{H2}/P_{MTS}=Q_{H2}/Q_{MTS}$=1 to 10) and deposition temperatures(T=1050~1300$^{\circ}C$). At the temper-ature of 1250$^{\circ}C$ the growth rate of SiC films increased and then decreased with decreasing the input gas ratio. The microstructure of SiC films was changed from granular type structure exhibiting (111) preferred orientation in the high input gas ratios to faceted columnar grain structure showing (220) in the low input gas ratios. The similar microstructure change was obtained by increasing the deposition temperature. These results were closely related to a change of deposition mechanism. Double layer structure having granular type and faceted ciolumnar grain structure from the manipulation of mechanism. Double layer structure having granular type and faceted columnar grain structure from the manipulation of the input gas ratio without changing the deposition temperatue was successfully fabricated through in -site process.

• Proceedings of the Korean Fiber Society Conference
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• 1996.10a
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• pp.124-130
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• 1996

The hydrocarbons containing more than 10 carbons(0.1% of total volume, C10+), residue of aromatization from aliphatic hydrocarbons, were condensated in the presence of catalyst aluminumchloride and cocatalyst nitrobenzene(NB) to be pitchs with desirable properties. The properties of pitch were affected by the concentration of cocatalyst chosen 20 and 30wt.%. The pitch with 30wt.% NB showed higher carbon yield and lower crystallinity than that with 20wt.% NB. The two pitches were heat treated at 1000C and measured of charge/discharge capacity of the carbon as an anode. The carbon prepared at 20wt.% NB exhibited excellent cyclic stability with a capacity of 218mAh/.g and that at 30wt.% exhibited rather low cyclic stability with higher capacity of 235mAh/g.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.565-574
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• 2019

Fischer-Tropsch synthesis process is a typical method for synthesizing hydrocarbons from syngas and is mainly known as iron (Fe) and cobalt (Co) catalysts. Currently, some technologies such as CTL (Coal to Liquid) and GTL (Gas to Liquid) are operated on a commercial scale depending on the products, but the research to produce light hydrocarbons and middle distillates directly has not been commercialized. Therefore, in this study, domestic studies for direct production of light hydrocarbons and middle distillates are summarized and the effect of catalyst preparation, promoter addition, zeolite combination on product selectivity is investigated.

• Journal of Environmental Impact Assessment
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• v.30 no.2
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• pp.132-139
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• 2021

Laboratory-scale experiments were conducted to assess the effect of oxidative decomposition of polycyclic aromatic hydrocarbons (PAHs) in field soil using peroxy-acid. The study soil texture is sandy soil containing 19.2 % of organic matter at pH 6.8. Among polycyclic aromatic hydrocarbons (PAHs) in the study soil, the concentration of benzo(a)pyrene is 2.23 mg/kg which is three times higherthan the Korea standard level. Therefore benzo(a)pyrene was selected as the target study PAH for the treatment by peroxy-acid oxidation using peroxy-acid coupled with hydrogen peroxide, and the efficiency of the oxidative decomposition of benzo(a)pyrene was assessed for the different organic acids and dosages of an organic acid and hydrogen peroxide. Propionic acid among the tested organic acids showed the highest efficiency of benzo(a)pyrene reduction in the peroxyacid oxidation treatment and finally satisfied the Korea standard level.

• Resources Recycling
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• v.30 no.4
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• pp.46-53
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• 2021

Biomass can be considered as chemical energy obtained from nature, and includes all living organisms such as plants, animals, and microorganisms. Biomass is eco-friendly, is easily obtainable from the environment, and can be recycled without special treatment processes. Biomass can also be converted into bioenergy fuel through pyrolysis and fermentation. Therefore, it has been considered as a renewable energy source, which prevents the depletion of natural resources such as fossil fuels. In this study, torrefaction to increase the carbon content in various types of biomass sources (sawdust, rice straw, rice bristles, coffee ground, and waste wood) was conducted under an inert atmosphere and at a temperature of 523~573K. The possibility of using torrefied biomass as an alternative to solid fuel for industrial purposes was analyzed by examining the carbon concentration and combustion behaviors.

• Clean Technology
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• v.15 no.1
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• pp.31-37
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• 2009

This study deals with the production process of activated carbons from the sewage sludge char by chemical activation reaction. KOH and NaOH were used as activating agents, which react well with carbon. From the experiments, it was found that activated carbons made with KOH treatment had better physicochemical properties in terms of iodine number and BET value than those made with NaOH treatment. It was also found that the optimal deposition ratio of an activating agent to the sewage sludge char was 75 wt% of KOH and 50 wt% of NaOH. Activated carbons were washed out by distilled water after neutralization with 5 M hydrochloric acid solution. The activated carbons that were produced from a sewage sludge char at this optimal conditions have BET surface areas of approximately $600m^2/g$.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.439-445
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• 2022

In this study, Silicon and petroleum pitch were coated on the surface of Si/C fiber manufactured using electrospinning to improve the electrochemical performances. SiO₂/PAN fiber was prepared by electrospinning with TEOS and PAN at various ratios dissolved in DMF. The characteristics of carbonization, reduction, and pitch coating processes were investigated for the optimal process of the pitch coated Si/C fiber anode composite. Anode composite prepared with TEOS/PAN = 4/6 (CR-46) after carbonization and reduction process has a capacity of 657 mAh/g. To improve capacity and stability, Si powder and PFO pitch were coated at the surface of CR-46. When the pitch composition was fixed at 10 wt%, it was found that the capacity increased as the weight ratio of silicon increased, but the stability decreased. The pitch coated Si/C fiber composite with 10 wt% silicon has high capacity of 982.4 mAh/g and capacity retention of 86.1%. In the test to evaluate rate performance, the rate capability was 80.2% (5C/0.1C).

• Proceedings of the Membrane Society of Korea Conference
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• 1996.04a
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• pp.57-57
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• 1996

공기로 붜 산소와 질소의 분리, C$_1$-화학공정중의 부산물 가스분리등은 많은 에너지를 필요로 하는 화학공정이다. 이런 에너지 집약적 분리공정에서는 에너지효율을 높이기 위하여 막분리공정의 적용을 고려할 수 있다. 막분리에 적용되는 기체분리막은 분리의 원리에 따라 (a)knudsen flow separation, (b)Molecular sieving separation, (c) Solution-diffusion separation 등으로 나눠진다. 이중 molecular sieving membrane (공경: <7${\AA}$)은 solution-diffusion막보다 높은 투과도와 선택도를 갖기 때문에 최근에 들어 높은 관심을 받고 있다. 그러나 장기성능저하, fouling제거, 제조방법상의 문제점에 대한 해결이 요구되고 있다. 본 연구에서는 폴리이미드를 열분해법을 이용하여 탄화시켜 탄소분자체막을 제조하였고 막제조시에 발생하는 기계적 강도약화를 해결하기 위한 고찰을 행하였다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.201-207
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• 2002

배가스 탈황 공정은 흡수제의 형태에 따라 습식과 건식, 반응생성물로부터 흡수제의 회수여부에 따라 재생법과 비재생법으로 분류할 수 있으며, 현재 전 세계적으로 상용화되고 있는 처리공정은 비재생 습식 석회석-석고 공정이 채택되어 전체 설치용량의 80% 이상을 점유하고 있다.(중략)

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.251-253
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• 2007

현재 다이아몬드 공구에서 극세선에 브레이징 공정을 이용하여 다이아몬드를 접합하는 기술은 국내외 적으로 전무한 상태이다. 이 연구는 금속 와이어에 다이아몬드를 브레이징을 실시하여 최적의 와이어 브레이징 공정법을 개발 하는데 있다. 다이아몬드와 금속필러메탈 접합 계면에서의 금속성분과 탄화물의 거동을 분석하며, 브레이징에 따른 와이어의 물성 변화를 관찰하였다. 금속필러로는 Ag-Cu-5Ti(wt.%)을 사용하였으며, 와이어는 스테인리스를 이용하였다. 브레이징 공정은 진공 접합 장치를 이용하여 $800{\sim}1000^{\circ}C$에서 유지시간 $5{\sim}30$분로 실시하였다. 브레이징된 다이아몬드는 $900{\sim}950$도, 유지시간 10분 사이에서 각각 건전한 계면과 표면을 얻을 수 있었으며, 계면에서 Ti-rich상과 화합물이 확인되었다. 또한 열처리 따른 와이어의 최적의 건전한 상태를 고찰 하였다. 다이아몬드와 Ag계 브레이징 필러의 계면에서의 미세조직 및 화학반응의 메커니즘은 SEM, EPMA, XRD를 이용하여 분석하였다.