• Membrane Journal
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• v.26 no.3
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• pp.220-228
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• 2016

Carbon molecular sieve (CMS) hollow fiber membranes were prepared by carbonizing a polyimide precursor manufactured by non-solvent induced phase separation process. Gas separation performance of CMS hollow fiber membrane was investigated on the effect of three carbonization conditions. CMS membrane with the highest gas separation performance was obtained at the pyrolysis temperature of $250-450^{\circ}C$: $N_2$, $SF_6$, and $CF_4$ permeance were 20, 0.32, 0.48 GPU, respectively, and $N_2/SF_6$ and $N_2/CF_4$ selectivities were 62 and 42, respectively. In the $SF_6/CF_4/N_2$ mixture gas test, when the stage cut was 0.2, the recovery ratio of $SF_6$ and $CF_4$ was over 99% and 98%. $SF_6$ concentration ratio was 4.5 times higher than the $SF_6$ concentration at the feed side. From the results, it was concluded that CMS membrane was one of the promising membranes for recovery Perfluorocompound gases process.

• Journal of Adhesion and Interface
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• v.24 no.3
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• pp.77-85
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• 2023

In this research, polymeric anionic surfactants having various molecular weights and acid values were synthesized using a continuous stirred tank reactor (CSTR). The CSTR has an advantage of higher production rate and more constant product properties compared to batch and semi-batch reactors. The polymeric surfactants were made using butyl acrylate as a hydrophobic group and acrylic acid as a hydrophilic group. The synthesized polymeric surfactants were ionized with alkali solution and were used as an anionic surfactant. To investigate the properties as a surfactant, the properties of the synthesized surfactant, such as acid value, critical micelle concentration (CMC) and molecular weight, were measured. The results showed that the acid values of the polymeric surfactants were 60 to 380 and a number average molecular weight were 8,000 to 13,000 g/mol. Also, it was found that the CMC was around 0.01 g/ml, which showed similar level values with ordinary surfactant. To prove the performance of the polymeric surfactant, acrylic emulsion PSAs were synthesized using the acquired polymeric surfactant. The results showed that the maximum peel strength of 21.24 N/25mm when acid value was 150 and molecular weight was 8,500 g/mol. The values of peel strength and initial tack of acrylic emulsion PSAs using polymeric surfactant synthesized in this study showed much higher than those of reference PSAs synthesized using ordinary anionic surfactant, SDS (Sodium Dodecyl Sulfate) and SDS/TRX (Triton X-100).

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.129-134
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• 2008

Five antioxidative active substances were isolated from the EtOAc layer (20 g/56.2 g) of Korean black raspberry (Rubus coreanus Miquel) wine (11 L, black raspberry 15.7 kg fresh wt. eq.) by various column chromatography and high performance liquid chromatography (HPLC). Proton nuclear magnetic resonance ($^1H$-NMR) spectroscopy and gas chromatography Electro Ionization-Mass Spectrometry (GC-EI-MS) identified these as 4-hydroxybenzoic acid (1, 0.1 mg), 3,4-dihydroxybenzoic acid (2, 0.3 mg), 4-(2-hydroxyethyl)-phenol (3, 0.6 mg; tyrosol), pyrocatechol (4, 0.3 mg), 3,4,5-trihydroxybenzoic acid ethyl ester (5, 0.6 mg; ethyl gallate). The presence of 1 and 2 in Korean black raspberry has previously been reported. However, the presence of 3-5 in Korean black raspberry, and the identification of 1-5 from the Korean black raspberry wine have never before been reported.

• Bulletin of Food Technology
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• v.8 no.4
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• pp.179-191
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• 1995

Thermoanaerobacter ethanolicus유래 thermophilic amylopullulanase의 thermophilicity와 thermostability의 기작을 규명하기 위하여 N-말단과 C-말단으로부터 nested deletion mutatnt와 sitedirected mutagenesis등에 의한 변이효소를 제조, 분석하였다. 이러한 까다로운 변이효소를 제조하여 amylopullulanase의 특정부위가 효소의 thermophilicity와 thermostability에 관여하고 있는 것을 확인했다. N-말단의 start amino acid에서 194와 324 아미노산잔기에 이르는 부위 (TPR)가 이 효소의 높은 최적반응온도의 유지에 관련되어 있고 1102와 1224잔기에 이르는 부위 (TSR)는 thermodenaturation이 잘 일어나지 않도록 하고 있었다. 야생형 amylopullulanase (Apu), 변이효소중 ApuN342와 ApuN106/C379는 비슷한 효소비활성과 Km값을 가지고 있었다. TPR부위의 site-directed mutagenesis에 의한 변이효소중 P240A (proline$\rightarrow$alanine), P244A, P240A-P244A는 야생형의 최적반응온도 $80^{\circ}C$와 똑같았지만 효소의 열안전성(반감기)는 $85^{\circ}C$에서 21, 105, 128분을 보여 주었다. TSR에서의 변이효소중 P1159A, P1202A는 열안전성은 비슷하였지만 반응최적온도는 $85^{\circ}C$와 $90^{\circ}C$로 야생형 Apu보다 오히려 높아졌다. 따라서 proline은 분자내에서 thermophilicity와 thermostability를 항상 증가시키는 쪽으로 영향을 주지 않는 것으로 보인다. Proline은 그 위치와 주위의 다른 아미노산잔기와 같이 종합적으로 분자의 구조에 영향을 미치고 있는 것으로 판단된다.

• Polymer(Korea)
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• v.34 no.6
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• pp.501-506
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• 2010

Natural chitosan has high molecular weight and the poor solubility in water. Water-soluble chitosan with low molecular weight was prepared by the hydrolysis method. In order to develop an efficient gene delivery carrier, chitosan was conjugated with lipoic acid to form the comb-type copolymer. The copolymer with the amphiphilic property formed the self-assembled nanoparticles in the aqueous solution. The average size of nanoparticles was 217.6 nm and the average size of nanoparticles/DNA complex was 170 nm. New chitosan-lipoic acid copolymer showed the low cytotoxicity and 10 times higher transfection efficiency than that of the pure chitosan.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.240-240
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• 2003

SiC 섬유의 고온강도를 향상시키기 위한 소결조제로 boron, aluminum 등을 사용할 수 있다. 본 연구에서는 폴리카보실란에 aluminum precursor를 첨가한 후 중합반응을 거쳐 Al-contained polycarbosilane을 합성하였다. 합성된 Al-contained polycarbosilane을 용융방사하여 섬유화 하고 열분해 공정을 통해 Si-Al-C-O 나노복합 섬유를 제조하였다. 먼저 aluminum butoxide와 polycarbosilane(commercial)을 200m1 xylene에 용해시켜 14$0^{\circ}C$에서 1시간 동안 reflux하였다. evaporator를 이용하여 xylene를 제거한 후 autoclave에서 25$0^{\circ}C$/30$0^{\circ}C$ 중합과정을 통해 가교결합 시켰다 이와 같이 합성된 시료는 ICP분석을 통해 aluminum 함량을 확인하였고 FT-IR(Fig.1) 및 GPC분석(Fig.2)으로부터 화학구조 및 분자량변화를 확인하였다. aluminum 첨가량이 증가함에 따라 Si-H/Si-$CH_3$의 결합크기의 비가 감소하였으며 이로부터 aluminum butoxide와 polycarbosilane의 가교결합이 이루어진 것으로 보이며 중합 후 분자량의 증가 또한 가교결합에 의한 결과로 사료된다 열무게감량(TGA) 측정 결과는 40$0^{\circ}C$부터 유기리간드의 분해가 일어나며 80$0^{\circ}C$이상에서 세라믹화 과정이 완료되었음을 알 수 있었다 또한 aluminum 첨가량이 증가함에 따라 세라믹 수율도 증가하였음을 확인하였다. 합성된 aluminum-contained polycarbosilane은 20$0^{\circ}C$에서 1시간 동안 불융화과정을 거쳐 환원 및 진공 분위기에서 고온 열처리하였으며 이로부터 얻어진 시료에 대해 XRD분석을 수행하였다. SEM과 TEM을 이용하여 미세구조를 관찰하였다.

• Polymer(Korea)
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• v.30 no.1
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• pp.50-55
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• 2006

When the monodisperse polystyrene(PS)/HDDA polymer particles were synthesized via one-step polymerization using polystyrene seed particles by dispersion polymerization, the effects of 1) the molecular weight of seed polymer particles, 2) the ratio of the absorbed HDDA to the seed polymer particles (swelling ratio) and 3) seeded polymerization rate on the surface morphology of PS/HDDA polymer particles were investigated. It was observed that the creation of the crater shaped defect on the surface of PS/HDDA polymer particles was irrespective of the molecular weight of seed polymer ant swelling ratio. But its surface morphology could be controlled by the change of the seeded polymerization rate.

• Membrane Journal
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• v.19 no.2
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• pp.145-149
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• 2009

The aim of this paper is to investigate removal of salts in hydrolyzed sericin solution by a prepared nanofiltration membrane. The nanofiltration membrane was prepared by the interfacial polymerization method, and then compared with commercialized nanofiltration membrane in terms of salts removal. The sericin solution was hydrolyzed by a protease. The molecular weight distribution of the hydrolyzed sericin was determined by electrophoresis method. Relative flux measurements were carried out to investigate membrane fouling.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.339-339
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• 2011

기존의 광학리소그래피방법으로는 나노크기의 패턴을 형성하는데에 있어서 많은 제약이 있으며, 사실상 수십나노크기의 패턴을 형성하는데에는 전자빔리소그래피등 새로운 패턴형성 방법이 요구되고 있다. 블록 공중합체를 이용한 나노 패턴은 서로 다른 화학적 구조를 가지는 고분자들이 공유결합으로 연결되어 있는 분자구조를 이용하여, 하나의 분자 내에 서로 다른 블록들이 상분리를 일으키려는 것과 동시에 이들의 공유결합으로 인해 그 정도가 제한되는 것을 이용하여 라멜라, 실린더, 구 등의 주기적으로 배열된 형태의 구조물을 형성하는 패터닝 기술이다. 블록 공중합체를 이용한 나노크기의 패턴 형성은 열역학적으로 안정적인 구조이며, 대면적으로 구현 할 수 있어서 차세대 소자제작을 위한 제작기술로 많은 관심을 가지고 있다. 하지만 블록공중합체를 이용한 나노패턴 기술은 선행적으로 나노구조체를 결함이 없고, 원하는 형태로 제작 할 수 있는 공정의 확립이 필요하다. 따라서 본 연구에서는, 이러한 블록 공중합체을 이용한 나노패턴을 제조하는 공정에서, 폴리스틸렌과 실리콘 산화물 박막과의 표면반응을 막기 위한 Self-Assembly Monolayers (SAMs) 처리 공정이 패턴 형성에 미치는 영향을 알아보기 위하여 MPTS의 농도 및 처리시간을 변화시켰다. 나노패턴을 분석, 확인하기 위하여 Atomic Force Microscopic (AFM)과 Field Emission Scanning Electron Microscope (FESEM)을 이용하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.103-107
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• 2004

This paper was studied the properties of materials for treatment of anionic chromate$(CrO4^{-2})$ in industrial wastewater. Ion exchange fiber, poly(acryloamidino diethylene diamine) with ion exchange and adsorption was prepared PAN fiber and diethylenetriamine under $AlC1_3$ catalyst at $120^\circ{C}$ and was analyzed $^{{13}/C-NMR$}$ and FT-IR spectroscopy. The maximum adsorption and the coordination of chromate on chelating fiber were analyzed FT-IR spectra. We proposed the coordination structure with inter/intramolecular bond.