• Journal of the Korean Vacuum Society
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• v.21 no.3
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• pp.178-184
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• 2012

Carbon coils could be synthesized on nickel catalyst layer-deposited silicon oxide substrate using $C_2H_2$ and $H_2$ as source gases and $SF_6$ as an additive gas under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils were investigated as functions of additive gas flow rate and the cycling on/off modulation of $C_2H_2/SF_6$ flows. Even in the lowest $SF_6$ flow rate (5 sccm) in this work, the cycling on/off modulation injection of $SF_6$ flow for 2 minutes could give rise to the formation of nanosized carbon coils, whereas the continuous injection of $SF_6$ flow for 5 minutes could not give rise to the carbon coils formation. With increasing $SF_6$ flow rates from 5 to 30 sccm, the cycling on/off modulation injection of $SF_6$ flow confines the geometry for the carbon coils to the nanosized ones. Fluorine's role of $SF_6$ during the reaction was regarded as the main cause for the confinement of carbon coils geometries to the nano-sized ones.

• Membrane Journal
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• v.16 no.2
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• pp.144-152
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• 2006

Elastomer-clay nanocomposite membranes were prepared by melt intercalation mothod with internal mixer. We are used NMR, Ionomer, SEBS (Styrene Ethylene Butadien styrene Copolymer) as elastomer, and modified clay. Gas barrier property of the elastomer-clay nanocomposites membranes were investigated by a gas permeability of $CO_2,\;O_2,\;N_2$ at room temperature. Gas permeability through the elastomer-clay nanocomposite membranes increased due to increased tortuosity made by intercalation of clay in elastomer.

• Membrane Journal
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• v.4 no.4
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• pp.171-186
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• 1994

• Membrane Journal
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• v.23 no.2
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• pp.136-143
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• 2013

Recently, a novel coating method using an aqueous doapmine solution was proposed, the deposited coating was found to have extraordinarily strong-adhesion to numerous materials such as metal and polymers. However, it has suffered from many controversy in scientific fields due to its final structure and deposited mechanisms. Here, we have proposed a new structure for final dopamine product coupling with solid state spectroscopic, thermal behavior, and gas transport behaviors of dopamine coated microporous polyethersulfone membranes. In its final analysis, the results represented that it is a supramolecular aggregated of monomers consisting of 5,6-dihydroxyindoline and its derivative in contrast to previously proposed polymeric structure.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.890-893
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• 2012

Gas hydrates are solid crystal structures formed by enclathration of gaseous guest species into 3-dimensional lattice structure of hydrogen-bonded water molecules. These compounds can be potentially used as an energy storage/transportation medium because they can hold a large amount of gas in a small volume of the solid phase. In addition, huge amount of natural gas, buried in seabeds or permafrost region in the form of the solid hydrate, is regarded as a future energy source. In this study, synthesized natural gas, whose composition is 90.0 mol% of methane, 7.0 mol% of ethane, and 3.0 mol% of propane, was used to identify formation behaviors of natural gas hydrates for the purpose of applying the gas hydrate to a storage/transportation medium of natural gas. According to the experimental results obtained by means of the solid-state NMR and high-resolution powder XRD methods, it is found that formed natural gas hydrates have crystal structure of the structure-II hydrate, and that methane occupies both small and large cages, while the others only occupy large ones. In addition, both the NMR spectroscopy and the gas chromatograph showed that there exists preferential occupation among the natural gas components during the hydrate formation. Compositional changes after the hydrate formation revealed that the preferential occupation is in order of propane, ethane, and methane (propane is the most preferential guest species when forming natural gas hydrates).

• Journal of radiological science and technology
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• v.29 no.3
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• pp.147-155
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• 2006

The crystal structures of fully dehydrated $K_3Na_8H-A(R_1=0.0478,\;R_2=0.0458\;and\;a=12.257(1){\AA})$ have been studied by single-crystal x-ray diffraction methods in the cubic space group. Pm3m in order to understand the structure of the zeolite as a gas storage medium and the mechanisms based on the encapsulation and decapsulation processes of gas molecules. In the crystal structures of dehydrated $K_3Na_8H-A$, three $K^+$ ions per unit cell are located on the 8-oxygen ring(0.0, 0.4531, 0.4531) and eight $Na^+$ ions per unit cell are located near the centers of 6-oxygen rings. Each $K^+$ ions on the 8-ring is $2.87(2){\AA}$ and $2.79(1){\AA}$ away from two kinds of framework oxygen atoms. These values are more realistic than previously known values in $K_{12}Na-A$. The exact positions of $K^+$ ions are ca. $0.8{\AA}$ away from the centers of the 8-rings which are previously reported as the preferred location of $K^+$ ions. Because the zeolites frameworks are stabilized as the results, more effective controls of gas molecules at encapsulation, decapsulation, and storage are achieved. Additionally, the available storage volumes are also maximized and more volume of gases can be stored in the materials. Therefore, oxygen storage bottles in hospital can be minimized and portable oxygen bottles for patients in emergency can be developed by using the materials.

• Polymer(Korea)
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• v.24 no.4
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• pp.453-458
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• 2000

The permeability of oxygen and nitrogen was investigated from the polymeric LB films containing imidazole-metal ion complexes and compared with its corresponding cast films on porous membrane filters. The amphiphilic polymer, poly(N- (2-(4-imidazolyl)ethyl)-maleimide-alt-1-octadecene) (IM-O), was synthesized by reaction of poly(maleic anhydride-alt-1-octadecene) with histamine. The IM-O nonolayer showed high stability on Fe (III) ion-containing subphase. The molecular structure in the LB films was investigated by means of FT-IR spectroscopy. The metal ion concentration incorporated into the LB films was determined by means of XPS measurements. The mechanical stability and uniformity of the LB films on porous substrates were indirectly evidenced by SEM observation. The LB and cast films showed more or less higher selectivity toward nitrogen, and high permeability was found to both the oxygen and nitrogen.

• Composites Research
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• v.15 no.6
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• pp.24-29
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• 2002

For the development of all composite unmanned aerial vehicle(UAV), the consideration for manufacturing in design phase and events in composite parts fabrication, subassembly and final assembly are summarized. In design phase, to maximize the advantages of composite material such as cocuring, cobonding and secondary bonding for manufacturing, the advanced structural concept is introduced. For the curing of designed parts, the manufacturing tools for composite parts are designed and manufactured. The assembly jigs are designed to meet dimensional tolerance requirements of the vehicle structure. And the inspection criteria are established and applied for the manufacturing. Technical data for inspection items and methodologies are summarized to utilize for the exclusive specifications of the manufacturing sequence.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.47-47
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• 1999

2.45 GHz 마이크로웨이브를 이용하는 electron cyclotron resonance plasma enhanced chemical vapor deposition(ECR-PECVD)방법으로 다이아몬드성 탄소박막(diamond-like carbon, DLC)을 증착하였다. DLC 박막의 산업 응용을 위해서는 높은 경도와 밀착력이 필요하다. 그래서 본 실험에서는 DLC 박막의 산업 응용을 위하여 ECR-PECVD 방법으로 증착된 DLC 박막의 분석결과로부터 DLC 박막의 물성과 증착조건의 관계를 조사하였다. 기판으로는 실리콘 웨이퍼와 실험용 SUS 판을 사용하였다. 아르곤 가스를 주입하여 ECR 마이크로 웨이브 플라즈마와 negative DC bias로 기판을 플라즈마 세척한 후, 수소와 메탄가스를 반응기체로 하여 DLC 박막을 증착하였다. 박막 증착시에 13.56MHz RF 전원 공급장치로 기판에 전원을 공급하였다. DLC 박막 증착의 변수는 반응기체의 호합율, 마이크로웨이브 파워, 프로세스 압력 및 RF 전원공급장치에서 유도되는 negative self DC bias 등이다. 이때 사용된 반응기체의 혼합율(메탄/수소)은 10~50%이고, 수소 가스 흐름율은 100sccm, 메탄은 10~50sccm이다. 마이크로웨이브의 크기는 360~900W, negative self DC bias는 -500~-10 V였다. 그리고 본 실험에서는 높은 증착율을 고려하여 프로세스 압력을 10~30mTorr까지 조절하였다. ER-PECVD 방법으로 증착된 DLC 박막은 SEM으로 단면, $\alpha$-Step으로 두께, Raman 분광계로 탄소 결합구조, FTIR 분광계로 탄소와 수소 결합구조, Micro-Hardness로 경도 그리고 Scratch Tester로 밀착력 등을 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.512-512
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• 2012

최근 저온 대기압 플라즈마 장치의 개발로 대기 및 수질 환경, 바이오 메디컬분야로의 응용 연구가 활발히 진행되어 공기 중 플라즈마의 살균 및 정화효과에 대한 많은 결과가 발표되어 왔다. 본 연구는 면방전 구조의 DBD플라즈마 소스를 제작하여 He과 Ar 기체를 유입하여 미생물인 E.Coli의 변화를 관찰하였다. 면방전 구조의 DBD플라즈마 소스는 1.8 mm 두께의 유리기판위에 포토리소그라피 공정으로 미소전극을 형성하여 고밀도의 방전 셀을 형성하였으며 방전시 발생하는 열 효과를 제어하기 위하여 냉각장치를 제작하여 장착했다. 또한 유리기판과 포토 리소그라피 공정은 방전영역에 제한없이 다양한 크기의 소스제작이 가능하다. 셀 피치가 $400{\mu}m$이며 $cm^2$ 당 200여개의 방전 셀로 구성되어 있어서 기존 메쉬타입의 DBD플라즈마 장치에 비해 균일하게 플라즈마를 조사할 수 있으며 플라즈마 제트 장치에 비해서는 넓은 면적을 동시에 조사할 수 있게 되었다. Ar 과 He기체를 3 L/min의 유량으로 방전공간에 유입하면서 1kV의 구동전압으로 플라즈마를 발생 하였으며, 플라즈마의 조사시간을 20 s, 40 s, 60 s 간격으로 변화를 주어 E.Coli의 변화를 관찰하였다.