• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.239.1-239.1
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• 2015

1차원 탄소나노재료이며 한 겹의 흑연을 말아 놓은 형태인 단일벽 탄소나노튜브(Single-walled carbon nanotubes, SWNTs)는 감긴 형태에 따라 반도체성, 금속성 성질을 나타내는 특이성과 우수한 기계적 성질을 지니고 있어 광범위한 분야로 응용이 기대되어왔다. 이러한 SWNTs의 응용가능성을 실현시키기 위해서는 보다 경제적, 산업적인 면에서 손쉬운 합성방법의 개발이 필요한 실정이다. SWNTs의 합성 방법들로는 아크방전법과 레이저 증발법, 그리고 열화학기상증착법(Thermal chemical vapor deposition, TCVD) 등이 이용되었다. 이 중 TCVD법은 대면적의 균일한 CNTs를 합성할 수 있다는 장점이 있다. 그러나 탄화수소가스를 효율적으로 분해하기 위하여 $800^{\circ}C$ 이상의 고온 공정이 요구되며, 이는 경제적, 산업적인 면에서 사용이 제한적이다. 따라서 저결함, 고수율의 SWNTs를 저온합성 할 수 있는 공정의 개발이 지속적으로 필요하다. 본 연구에서는, TCVD법을 이용하여 에틸렌 원료가스로 SWNTs의 저온합성 가능성을 확인하였다. 합성을 위한 기판과 촉매로는 실리콘 산화막 기판(SiO2/Si wafer)에 철 나노입자를 지닌 ferritin을 스핀코팅 후 산화하여 이용하였다. 저온합성 공정의 변수로는 합성온도와 원료가스인 에틸렌의 분율을 설정하여, 변수가 SWNTs의 결정성과 수율에 미치는 영향을 고찰하였다. 합성된 SWNTs의 분석의 용이함과 손지기(Chirality)의 제어를 위하여 나노 다공성 물질인 제올라이트(Zeolite)를 보조 기판으로 사용하였다. 실험결과 에틸렌 원료가스로 합성한 SWNTs는 $700^{\circ}C$ 부근의 저온에서도 합성이 가능함을 확인하였다. 또한 에틸렌 원료가스의 분율과 합성시간의 정밀한 제어를 통해 SWNTs의 합성온도를 더욱 감소시키는 것도 가능할 것으로 예상된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.232.1-232.1
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• 2015

흑연 박리를 통해 형성된 탄소나노플레이트를 탄소나노튜브 합성을 위한 지지체로 적용하여 탄소나노플레이트 위에 직접 탄소나노튜브를 합성함으로써 3차원 구조의 탄소나노튜브/탄소나노플레이트 나노혼성체를 합성하였음. 흑연의 박리를 통해 탄소나노플레이트를 제조하기 위해서 층간화합물 삽입과 열처리를 통해 팽창흑연을 제조하고, 물리적 분쇄 과정과 액상 고압균질기 방법을 통해 두께 30nm 이하, 수 마이크론 크기의 탄소나노플레이트를 제조하고 동결건조 방법으로 탄소나노플레이트를 제조하였음. 제조된 탄소나노플레이트 상에 탄소나노튜브 합성을 위해서 탄소나노플레이트 표면처리 공정을 적용하였는데, 표면처리 방법 및 물질에 따라 금속 촉매의 담지량 및 담지 형상이 결정되어 합성되어지는 탄소나노튜브의 합성 수율과 합성된 탄소나노튜브의 형성이 다르게 나타났다. 표면처리 방법으로는 산처리방법, 흡착성 고분자 처리법, 무전해 도금법, 무기산화물 처리법이 적용되었다. 또한 담지되는 촉매 종류 및 함량, 조촉매 적용에 따라 탄소나노튜브 합성 거동을 분석하여 최적 촉매시스템을 구축하여 촉매담지체 질량 대비 700% 이상의 고수율의 탄소나노튜브/탄소나노플레이트 혼성체 합성법을 개발하였다.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.239-242
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• 2000

Experimental studies on the effects of impeller to provide the microbial transglutaminase derived from Streptoverticillium mobaraense have been conducted. The optimal production medium was determined by latin-square design, and the effects of aeration and agitation were observed by using different sizes and shapes of impellers for the poduction of transglutaminase. The effects of pH and temperature were also evaluated for the production of transglutaminase in flasks. As a result, pH is more effective than temperature for both enzyme production and growth of the microorganism. The peak enzyme activity for transglutaminase in fermenter was 0.7 U/mL, but this was still well below the avereage enzyme activity, 1,3 U/mL, obtained in flask runs.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.278-281
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• 2003

This study was concentrated on investigating the optimum compositions of medium for the production of carbohydrolases complex. In order to maximize the activities of the carbohydrolases complex, cellulose and yeast extract were chosen as the best C and N sources, respectively. The concentrations of cellulose and yeast extract as well as minerals and amino acids were also studied. On the other hand, ${\beta}-glucosidase$ and ${\beta}-glucuronidase$ showed the maximal activities at $60^{\circ}C$ and pH 4, while ${\beta}-galactosidase$ showed the maximal activity at $50^{\circ}C$ and pH 3.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.103-110
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• 2001

Recently, ozone is utilized in various fields and its needs are expanding. Therefore, so many ozone generation methods have been reported in the last year, its main purpose is to get the high ozone concentration and to improve the ozone yield one of them is a Co-axial cylinder-type ozonizer. In this paper, a new ozonizer, which is using radio-frequency power supply, is fabricated to investigate discharge characteristics and ozone generation characteristics in accordance wish variation of grip spacing of electrodes.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.4
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• pp.22-29
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• 2002

This research was conducted to investigate the morphological characteristics of fine fibers produced during beating process of high yield pulp treated with ozone and the distribution of lignin in the produced fine fibers. Thermomechanical(TMP) pulp and chemithermomechanical(CTMP) pulp of spruce and CTMP of white birch were beaten to reach 200$m\ell$ CSF, and then the fine fibers were observed using ultraviolet microscope. The fine fibers produced from TMP and CTMP of spruce using treated with ozone for 15 minutes were fragments of fiber surfaces or cell corners, and most of them contained lignin. However, lignin was not observed in the fibers after 15 minutes of ozone treatment. The fine fibers produced from CTMP of white birch were broken pieces or fragments of fiber surfaces or cell corners. The lignin was observed in the fibers until 5min of ozone treatment but no lignin was observed after 5 minutes of ozone treatment. Different morphological characteristics of TMP and CTMP explained both the different morphological characteristics and the distribution of lignin observed in the fine fibers produced from the beating process of TMP and CTMP treated with ozone.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.2
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• pp.58-67
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• 2000

This study was carried out to acquire basic data necessary for the use of non-wood pulp. Various chemical pulping methods for rice straw to achieve higher yield, lower Kappa No. were investigated and then the physical properties of various pulps were tested. The results of this study were as follows: When various chemical pulps (Soda, Soda-AQ, Soda-$H_2O_2$, Soda-$Na_2S_2$, AS, AS-AQ, AS-$Na_2S_2O_3$, AS-$Na_2S_2O_4$, Kraft) were produced with rice-straw, the pulps with the highest yield and lowest Kappa No. were obtained with Soda-$Na_2S_2$and AS-$Na_2S_2O_4$pulps. For the breaking length, Soda and Soda-additive pulps(7.5~9.2km) were better than AS and AS-additive pulps(6.2~8.1km). Similarly, for the burst index, Soda and Soda-additive pulps(6.0~7.0 kPa.$m^2$/g) were better than AS and AS-additive pulps(4.5~6.3 kPa.m$^2$/g). But the tear index was showed 21.8-30.9 mN.$m^2$/g with a little different between pulping methods.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.66-68
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• 2006

New synthetic method of 2-mercaptobenzoxazoles and 2-mercaptobenzimidazoles was established using elemental sulfur, dichloromethane, inorganic base and catalysts in alcohol solvents. This reaction condition gave products in high yields.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.566-569
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• 2005

A novel purification method was developed for producing homoharringtonine from Cephalotaxus koreana, to guarantee high purity and yield. Our simple, efficient procedure for isolating and purifying homoharringtonine from C. koreanabiomass consisted of solvent extraction, synthetic adsorbent treatment, low-pressure chromatography, followed by high performance liquid chromatography (HPLC). The use of active clay treatment and silica gel low-pressure chromatography in the pre-purification process allowed for the rapid, efficient separation of homoharringtonine from interfering compounds and dramatically increased the yield and purity of crude homoharringtonine for high-performance liquid chromatography (HPLC) purification steps compared with alternative processes. Homoharringtonine could be obtained simply with high yield and purity from biomass using this purification method, while minimizing solvent use and the scale and complexity of HPLC operations for homoharringtonine purification. Purified homoharringtonine was identified and characterized.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.75-80
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• 1997

This research has been examined to measure the degree of the fiber damage of ozonenation high yield pulp in the beating process. Ozone treated the TMP(Thermomechanical Pulp) and CTMP(Chemithermomechanical Pulp) of spruce and the CTMP of birch has been beaten to be reached 200ml(freeness) of its content. It had been studied the forming of fiber distribution by treatment for long fiber, short fiber, fine with the above method. As ozone treatment time gets longer, the pulp has showed the tendency of increasing the fiber content of 28, 48mesh. Ozone treated fiber has been increased long fiber content by being added softness. By given longer ozone treatment time, the TMP and CTMP of spruce has showed the decreasing of fiber content. On the contrary, CTMP of birch has showed the increasing its fiber content. It had proved that the results of difference are rather closer to the species of tree than closer to the kinds of pulp. The fiber content of over 200mesh which has created in beating process demonstrates the decreasing of its fiber content by getting longer ozone treatment time. The softness of fiber can be extracted by the lignin of fiber surface that had been formed by ozone treatment. Thus we assume that the fiber in the process of beating obtains less physical damage.