• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.174-177
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• 1991

Fluorine-doped $SnO_2\;(SnO_2:F)$ films were prepared in ordinary atmosphere on borosilicate glass substrates using pyrosol deposition method starting from the solutions composed of $SnCl_4-5H_2O-NH_4F-CH_3OH-H_2O-HCl$ in an attempt to develop transparent conductors for use in amorphous silicon (a-Si) solar cello. The deposition rate of films increased with the increase in the content of $H_2O$, whereas it decreased with increasing the content of $CH_3OH$. When air was used as the carrier gas, the lowest electrical resistivity was obtained from a solution having $CH_3OH/H_2O$ mol ratio of about $2{\sim}3$ in the solution. The use of $N_2$ of the same flow rate as the carrier gab resulted always in the high resistive films, but the resistivity of the films decreased continuously with the increase in the content of $H_2O$. The surface morphology and preferred orientation of films were also affected by the solvent composition and the content of HCl in the solution. The room-temperature resistance of the films were fairly stable after heat-treatments up to $600^{\circ}C$.

• Korean Membrane Journal
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• 제6권1호
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• pp.55-60
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• 2004

In recent years, an increasing interest in membrane technology has been observed in chemical and environmental industry. Membrane technology has advantages of low cost, energy saving and environmental clean technology comparing to conventional separation processes. Pervaporation is one of new advanced membrane technology applied for separation of azeotropic mixtures, aqueous organic mixtures, organic solvent and petrochemical mixtures. Sodium alginate composite membranes were prepared for the enhancement of long-term stability of pervaporation performance of water-ethanol mixture using pervaporation. Sodium alginate membranes were crosslinked with CaCl$_2$ and coated with polyelectrolyte chitosan to protect washing out of calcium ions from the polymer. The surface structures of PAN and hydrolysed PAN membrane were confirmed by ATR Fourier transform infrared (FT-IR). A field emission scanning electron microscopy (FE-SEM; Jeol 6340F) operated at 15 kV. Concentration profiles for Ca in the membrane surface and membrane cross-section were taken by an energy dispersive X-ray (EDX) analyser (Jeol) attached to the field emission scanning electron microscopy (Jeol 6340F). Pervaporation experiments were done with several operation run times to investigate long-term stability of the membranes.

• 한국의류학회지
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• 제12권2호
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• pp.217-223
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• 1988

This study is to examine the cleaningproof by dry cleaning runs and parts(shoulder, belly, butt) of garment leathers tanned chrome. This study is composed of three methods of test; color difference test, surface view by scanning electron micrographs, mechanical properties measurement by KES-FB system. The results obtained were as follows: 1. In stiffening of parts of sample, the belly is the best degree in smoothness, fullness, softness. But that of the butt have been found to be the worst degree and to be thick. 2. In fading of parts, the shoulder is an extreme case, but the belly is the best among three parts. 3. In dry cleaning runs, the view after 3 runs has been found to be the best result. 4. The stiffening after dry cleaning 1 run have been low grade, for the sample absorb much solvent of dry cleaning. And, the fading and the decoloration are to be worse after 5 runs. Because the leather surface is affected by dry cleaning runs.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.465-472
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• 2002

This paper presents a study on the aging and recovery of HTV (high temperature vulcanized) silicone rubber used for outdoor insulators. UV irradiation, corona discharge and water immersion were employed as factors of the artificial aging. The effects of changes derived from these stresses on the tracking and arc resistance of silicone rubber were examined. We have investigated the aging phenomena of HTV silicone rubber by the above stresses using the surface energy calculation with contact angle measurement, solvent-extraction, and surface/volume resistivity and so on. These results showed that UV irradiation and corona discharge lead to nearly the same surface oxidation, but the percentage change of mobile low molecular weight by these stresses was different. Furthermore, the oxidized layer induced under UV irradiation restricted the recovery of hydrophobic surface. Water immersion little lowered hydrophobicity level and leaded to a loss of tracking and arc resistance. The degradation mechanism based on our results was discussed.

• 멤브레인
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• 제19권3호
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• pp.244-251
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• 2009

본 연구에서는 폴리이서설폰(polyethersulfone, PES) 중공사 막을 이용하여 6대 온실가스에 속하는 육불화황($SF_6$)을 질소 중에서 분리하고자 하였다. 제막 조건에 따른 막의 구조와 성능변화를 관찰하기 위하여 다른 비용매(아세톤, 에탄올)와 에어갭(air-gap) 그리고 실리콘 코팅을 통하여 성능변화를 관찰하였으며, 전자주사현미경(scanning electron microscope)을 통하여 구조 변화를 관찰하였다. $N_2$, $SF_6$ 단일기체 투과실험에서 제조된 막의 표면 실리콘 코팅을 통하여 최고 7.64의 선택도를 나타내어 3.4배 향상된 결과를 나타내었다.

• 대한조선학회 특별논문집
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• 대한조선학회 2013년도 특별논문집
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• pp.66-72
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• 2013

The demand for an ice class ship is rising expected to rise according to the increase of energy consumption and the opening of arctic sea routes. Ice class ship should be designed to cope with the severe environmental conditions of arctic sea such as a high mechanical impact and abrasion damage, caused by pack ice, ice bergs and low temperature. The ice class ship hulls are coated with an anti-abrasion and low friction coating such as a solvent free epoxy or high solid-volume epoxy. These coatings require two-component heating pump and a high grade surface preparation. In this study, the coating performances for the arctic vessels, such as puncture absorbed energy, abrasive wear loss, friction coefficients and impact absorbed energy were evaluated. Based on this study, a proper coating performance specification for the arctic vessels was proposed and coating selection guideline in terms of coating performance and workability was also established.

• 폴리머
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• 제38권3호
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• pp.371-377
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• 2014

Polydimethylsiloxane(PDMS)을 이용한 실리콘 변성 에폭시(PDMSME) 언더코팅액의 변성 조건이 코팅 도막물성에 미치는 영향을 살펴보았다. 실리콘 변성 에폭시 언더코팅 도막은 에폭시 코팅 도막에 비하여 월등히 우수한 휨성을 가지며 경도는 PDMS에 결합된 실란 커플링제에 의해 개환된 에폭시 링의 개수와 밀접한 관계를 가짐을 알 수 있었다. PDMS에 결합된 개환된 에폭시 링의 개수가 증가함에 따라 대기 중의 수분과의 수가교에 의한 가교밀도 증가에 의하여 경도가 증가되며 사용된 PDMS의 탄성적 성질에 의하여 휨성 또한 우수해짐을 알 수 있었다. PDMS 분자량이 증가됨에 따라 코팅 도막의 경도는 낮아지는 반면 실리콘의 함량 증가에 따른 표면 접촉각이 증가됨을 알 수 있었다. 이와 함께 PDMS의 분자량이 증가됨에 따라 아세톤 용액에 의한 PDMSME 주사슬의 entanglement 감소에 의하여 코팅액의 점도가 감소되며 그 결과, 언더코팅 도막의 표면 거칠기가 감소됨을 알 수 있었다.

• 폴리머
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• 제28권2호
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• pp.103-110
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• 2004

토코페롤을 함유하는 폴리($\varepsilon$-카프로락톤)(PCL) 마이크로캡슐은 액중건조법에 의하여 제조하였고, 제조 조건에 따른 마이크로캡슐의 특성과 PCL 필름을 사용하여 PCL의 분해거동을 측정하였다 제조된 마이크로캡슐의 크기 및 형태와 구조적 특성은 각각 SEM과 XRD를 이용하여 관찰하였다. 또한, 접촉각 측정을 통하여 심물질의 농도에 따른 마이크로캡슐의 표면자유에너지를 측정하였다. 실험결과, 마이크로캡슐은 유화제로 폴리(비닐 알코올)을 사용한 경우 안정된 구형의 마이크로캡슐이 형성되었고, 마이크로캡슐의 표면자유에너지와 PCL의 결정성은 감소하고, PCL 필름은 악 21일 후 분해가 시작되었다. 토코페롤의 방출특성은 UV/vis.에 의하여 측정하였으며, 마이크로캡슐의 방출속도는 교반속도의 증가와 함께 증가하였다. 이는 교반속도의 증가와 함께 감소된 마이크로캡슐 입자 크기에 의한 방출용액과 마이크로캡슐 사이의 계면의 증가에 의한 것으로 판단된다.

• 한국식품영양학회지
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• 제8권3호
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• pp.172-183
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• 1995

The nucleophilic substitution reactions of p-substituted benzyl bromide with l-substituted N,N-dimethylanilines in methanol and acetonitrile binary solvent mixture which is known to an isodielectric solvent system kinetically and the results are as follows. The positive charge is developed on the reaction center of the substrate and it means that the bond cleavage is preceded more than bond formation in the transition state on the analogy of Hammett px values. The bond form3tlon is not progressed in the case of electron donating substituent of substrate. However, the bond formation is much developed in the case of electron withdrawing substituent of substrate on the analogy of Hammett py values. The nucleophilic attacking ability is shown a highest at 80% (V/V) methanol content and the bond formation is well progressed at the same methanol composition on the result of a cross interaction coefficient, pxy. The result of transition state structure that is applicated to the potential energy surface model is in accord with the result that Is applicated to the reaction susceptibilities. The reaction Is subject to the polarity-polarizability term more than the hydrogen bond donor acidity term by application to the solvatochromic parameter eouation.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2003년도 가을 학술논문집
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• pp.650-654
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• 2003

원자력분야에서 방사성폐기물 처리 및 처분은 해결해야 할 중요한 문제가 된다. 보다 청정한 방법을 사용한 제염법이 요구되고 있다. 이산화탄소를 이용한 제염법은 두가지로 나눠지는데-킬레이트제를 이용한 방법과 에멀젼을 이용한 방법이다. 킬레이트제 방법은 시너지효과를 낼 수 있는 방안이 중요하다. 마이크로 에멀젼을 사용한 방법은 에멀젼 코어속에 산을 넣어 금속표면이나 토양에서 오염물질을 직접 꺼내는 방법이다. 표면제거율을 QCM을 사용하여 측정하였다. 에멀젼을 만드는데 사용된 계면활성제의 회수 방법에 대하여 아울러 논의하였다.