• 한국포장학회지
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• 제15권3호
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• pp.99-104
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• 2009

Soy protein isolate (SPI)-based nanocomposite films with three different types of nanoclays, such as Cloisite $Na^+$, Cloisite 20A, and Cloisite 30B, were prepared using a solution casting method, and their optical, tensile, and water vapor barrier properties were determined to investigate the effect of nano-clay type on film properties. Among the tested nanoclays, Cloisite $Na^+$, a hydrophilic montmorillonite (MMT), exhibited the highest transparency with least opaqueness, the highest tensile strength, and the highest water vapor barrier properties, indicating Cloisite $Na^+$ is the most compatible with SPI polymer matrix to form nanocomposite films. The film properties of SPI/Cloisite $Na^+$ nanocomposite films were strongly dependent on the concentration of the clay. Film properties such as optical, tensile, and water vapor barrier properties improved significantly (p<0.05) as the concentration of clay increased. However, the effectiveness of addition of the clay reduced above a certain level (i.e., 5wt%), indicating that there is an optimum amount of clay addition to exploit the full advantage of nanocmposite films.

• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 제3회 심포지움 (분리막 연구의 최신동향)
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• pp.73-85
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• 1995

The asymmetric hollow fiber membranes were prepared by the wet spining of polyetherimide dope solution and the effect of hollow fiber structures on the permeation characteristics of carbon dioxide and nitrogen gases through these membrane were investigated. As the concentration of the $\gamma$-butyrolactone (GBL) in dope solution, acting as a swelling agent was increased, the structure of hollow fiber was changed from the finger to sponge type. The permeabilities of gases (CO$_{2}$, N$_{2}$) through these membrane were measured over the wide range of pressure under different temperature. The effect of water vapor on the permeabilities of gases was also investigated. The measured permeabilities showed the different characteristics depending on the structure of membranes. It was found that the flow through the pores were dominant over the polymers matrix. Blocking effect by water vapor in the pores of skin layer greatly improved the ideal separation factor of carbon dioxide/nitrogen.

• 한국막학회:학술대회논문집
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• 한국막학회 1999년도 The 7th Summer Workshop of the Membrane Society of Korea
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• pp.23-26
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• 1999

Urethane block copolymers, containing soft segments such as polydimethylsiloxane (PDMS), polytertramethylene glycol(PTMG) and PEO-PPO-PEO (Poloxamer) block copolymer, were synthesized and examined for th vapor- phase separation of toluene from nitrogen stream by using vapor permeation equipment. Generally permeabilities of PTMG and PDMS based urethane membranes were higher than those of Poloxamer based urethane membranes. Organic vapor permeability in the PDMS and PTMG soft segment urethane membranes were greater than those measured in the Poloxamer films, due to more polymer swelling. The membranes performed best with toluene, with toluene/dry N2 seletivities ranging from 120~200 and permeablilities as high as 23$\times$10-9 mol/m2sPa for saturated toluene feeds at 23$^{\circ}C$.

• 한국염색가공학회지
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• 제23권2호
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• pp.131-139
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• 2011

This study surveyed on the synthesis of one-step type hydrophilic non-porous PU resin and the physical property of the coated fabric for the garment. Three kinds of chain extender such as MEG, 1,4-BD and NPG were used for the preparation of one-step type hydrophilic non-porous PU resin in order to examine the effect of chain extender on the physical properties of PU-coated fabric. And the effects of isocyanate on the physical properties of PU coated fabric were surveyed by mixing with various TDI and MDI ratios. In addition, the physical properties of the coated fabric treated with one-step type hydrophilic non-porous PU resin were examined according to the pre-treatment conditions such as cire finishing. Finally, the washing durability of the coated fabrics was assessed. The coated fabrics treated with PU resin synthesized with PEG1000, MEG and TDI/MDI (6/4) showed the best physical properties. Considering the pre-treatment conditions, best performance of hydraulic pressure, water vapor permeability, and water repellency were obtained with top roller rotation ratio of 150% under 50 ton pressure at $170^{\circ}C$.

• 한국재료학회지
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• 제11권6호
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• pp.512-518
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• 2001

6.5wt%Si강판을 낮은 철손실, 고투자율 그리고 자왜가 거의 0으로 우수한 자성재료로 잘 알려져 있다. 본 실험에서는 화학기상증착 (Chemical Vapor Deposition)으로 6.5wt%Si 강판을 만들었다 이 과정은 튜브 노내에서 실리콘의 함량이 낮은 Si강판에 SiCl$_4$가스를 반응시킨다. 이때 SiCl$_4$가스에서 분해된 Si의 원자들은 모재인 강판 표면에 증착되어 표면층에 Si가 풍부한 층을 형성한다. 마지막으로 고온에서 확산과정을 통하여 모재 내부로부터 실리콘의 함량이 균일한 강판을 얻을 수 있다. 0.5mm두께를 갖은 6.5wt%Si 강판의 철손실은 고주파수에서 약 8.92W/kg를 나타냈으며 투자율은 53,300으로 일반 실리콘강판, 즉 2.5wt%Si강판의 투자율 37,100보다 약 두배 가량 증가하였다. 또한 기계적인 특성을 평가하기 위해서 일반 0.5wt%Si강판과 773K의 온도에서 수시간 열처리한 강판을 인장실험 하였다. 따라서 수 시간 열처리한 시편에서 연신율이 증가함을 알 수 있었으며 파단면을 관찰한 결과 입 계파단면이 현저히 감소했음을 알았다

• 한국지반환경공학회 논문집
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• 제8권5호
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• pp.5-14
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• 2007

개발사업과 산업발달로 인하여 발생되는 유해화학물질과 유류사용량이 늘면서 화학물질과 유류를 저장하는 지하저장탱크에서의 오염물질 유출로 토양 및 지하수 오염이 심각해지고 있다. 또한, 산업지역, 공장지대가 밀집된 매립 지반에서는 투수계수가 낮아 오염물질 추출에 한계가 있다. 이러한 문제해결 방안의 하나로 연약지반 개량공법에서 사용되고 있는 연직배수재를 이용하여 기존의 복원기술인 진공추출공법, 토양세정공법의 효율을 증진시킨 연직배수시스템에 대한 연구를 수행하였다. 오염된 토양의 복원을 목적으로 사용한 연직배수시스템의 적용성 평가를 위하여 오염토양 복원시 오염지반에 영향을 주는 인자에 대한 지반공학적 특성 등을 분석하였다. 연직배수재의 수두손실 및 통수능 측정 결과, 진공압력과 연직배수재의 폭이 증가할수록 통수능은 배수재의 통수 단면적에 비례하여 증가하는 경향을 나타내었다. 축척효과에 의해 단면을 축소시킨 폭이 2.5 cm인 배수재의 경우에는 영향반경이 대략 14cm에서 16cm를 넘어가면서부터 간극수압이 더 이상 감소하지 않고 일정해지는 유효 영향범위로 판단하였다. 또한, 투기계수는 등가직경이 증가 할수록 감소하였으며, 흐름률이 높을수록 압력수두는 더 정밀한 값을 나타내어 평균 투기계수 값인 3.152 Darcy에 가까운 공기흐름률은 1,500~2,000 $cm^3/s$일 때 가장 정확한 값을 나타내었다.

• 한국표면공학회지
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• 제53권5호
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• pp.201-206
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• 2020

A SiOxCy(-H) thin film was synthesized by atmospheric pressure dielectric barrier discharge(APDBD), and a SiO₂-like layer was formed on the surface of the film by oxidation treatment using oxygen plasma. Hexamethylcyclotrisiloxane was used as a precursor for the SiOxCy(-H) synthesis, and He gas was used for stabilizing APDBD. Oxygen permeability was evaluated by forming an oxidized SiOxCy(-H) thin film on a PET film. When the single-layer oxidized SiOxCy(-H) film was coated on the PET, the oxygen gas permeability decreased by 46% compared with bare PET. In case of three-layer oxidized SiOxCy(-H) film, the oxygen gas permeability decreased by 73%. The oxygen permeability was affected by the thickness of the SiO₂-like layer formed by oxidation treatment rather than the thickness of the SiOxCy(-H) film. The excellent corrosion resistance was demonstrated by coating an oxidized SiOxCy(-H) thin film on the silver-coated aluminum PCB for light emitting diode (LED).

• 한국지반신소재학회논문집
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• 제7권4호
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• pp.1-8
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• 2008

토양증기추출공법(SVE)은 불포화 지반상태에서 휘발성 유기화합물(VOCs)과 유류오염 물질을 제거하는데 효과적이고 경제적인 공법중의 하나이다. 그러나 토양증기추출공법은 투기계수가 1 Darcy보다 작은 실트질 흙과 같이 낮은 투기계수를 가진 지반에서는 비효율적이다. 본 연구의 목적은 연직배수재를 토양증기추출기술중 관정으로서의 적용성과 공기 흐름 패턴에 대한 해석적 방법이다. 즉, 연직배수재를 이용한 실내 모형실험의 공기 추출 시험 결과를 바탕으로 하여 단일 배수재로서의 수치해석 모델을 검증하였다. 또한, 추출 시험결과로 투기계수를 결정하여 단순 분석적 접근의 유효성도 평가하였다.

• 복식
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• 제58권9호
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• pp.29-37
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• 2008

The purpose of this study was to investigate insulation of thermal clothing under still and dynamic air conditions(with 2.1m/sec air velocity) and decrease of insulation in both conditions, to analyze correlations among them, and to estimate insulation and decrease of insulation using factors, such as fabric insulation, fabric weight, clothing weight, air permeability, and water vapor resistance. A total of 25 kinds of clothing were tested(9 types for suits, 6 types of jacket, 5 types for shirts, and 5 types for trousers). The results of this study were as follows; Thermal resistance of clothing under the dynamic air condition decreased comparing to that of clothing under still air condition in all types of clothing. Decrease in shirts was the biggest(47.5%), followed by suits(39.51%), trousers(37.48%), and jackets(34.49%) in sequence. Thermal resistance of clothing under dynamic air condition showed very high correlation(0.98, p<0.01) with that of clothing under still air condition, followed by thermal resistance of fabric(0.86, p<0.01). Decrease in thermal resistance of clothing showed the highest correlation with air permeability. It didn't show correlation with other factors. Regression analysis showed that fabric thickness would be useful factor for estimating thermal resistance of clothing and air permeability also would be useful factor for estimating decrease in thermal resistance of clothing.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권6호
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• pp.48-55
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• 2013

This study aimed at characterizing unsaturated zone at the source zone area contaminated by DNAPL and investigating feasibility of soil vapor extraction (SVE). Five boreholes with three multi-level screens at the depth of 3.0~4.5 m, 5.5~7.0 m, and 8.0~12.0 m were installed at the source zone. Pneumatic tests were performed to determine the permeability of porous medium. Permeability was estimated to be 81.6 to 203.7 darcy, depending on the applied solutions, which was contradicted by grain size analysis of cored soil samples leading to 3.51 darcy. This is due to air flow through gravel pack during the early stage of pneumatic test. Pressure-drawdown curve in the late stage also well showed the leaky aquifer type, indicating air leakage to the ground. Air flow tests were also carried out to investigate air flow connectivity between multi-level wells, indicating that the horizontal air flow was well developed between the lower screens of the wells, not between the upper and middle screens due to the leakage to the surface. For the SVE test, there was no noticeable variation in TCE vapor concentration between three different test runs: 1. 8 hours daily for 5 days, 2. 24 hours together with air blowing at another well (BH1), 3. five consecutive days. Even for five-day consecutive test, total amount of removed TCE was estimated only to be as low as 46.5 g.