• KSBB Journal
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• 제8권3호
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• pp.200-208
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• 1993

음이온성 고분자 전해질의 하나인 알긴산을 이용 하여 알긴산막의 분리성능을 개선함과 동시에 막의 얀정성을 높이고, 막과 분리 대상물과의 화학적 친 화성을 제어하기 위하여 막의 가능기에 다양한 금속 이온으로 가교시킨 금속복합체 막을 제조하고, 그막 들이 투과증발 특성에 미치는 영향을 조사하여 다음 과 같은 결론을 얻였다. 1) 금속복합체 막들 중 IA족 금속이온으로 치환 한 경우에 저농도 에탄올 수용액에서 크게 팽윤되거 나 쉽게 부스러지는 경향이 있어 투과증발막으로 샤 용할 수 없었다. 2) 알긴산막에 비해 2가 금속으로 가교한 금속복 합체 막의 경우 막의 안정성 및 분라성능이 크게 향 상되는 것을 알 수 있었다. 3) 2가 금속 복합체 막들의 경우 분리계수는 Na a alg 막에 비해 약간 증가하는 경향을 나타낸 반면, 투과속도는 비슷한 경향을 나타내였다. 4) Ca-alg 금속복합체 막의 경우에 다른 금속복 합체 막들에 비하여 분리계수가 크게 증가하여 가장 우수한 성능을 나타내였다. 5) Ca-alg막의 경우 90wt.% 에탄올 수용액에서 분리계수는 6,420이었으며 투과속도는 $0.269kg/m^2.hr$로써 우수한 생능을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.533-538
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• 2003

It has been shown that ion implantation produces remarkable improvements in surface-sensitive physical and chemical properties as well as other mechanical properties, in polymers. In this study, ion implantation was performed onto polymer, PC(polycarbonate), in order to investigate surface hydrophilic property through contact angle measurement using distilled water. PC was irradiated with N, Ar, Xe ions at the irradiation energy of $20\;{\sim}\;50keV$ and the dose range of $5{\times}10^{15},\;1{\times}10^{16},\;7{\times}10^{16}\;ions/cm^2$. The contact angle of water has been reduced with increasing fluence and ion mass but increased with increasing implanted energy. The changes of chemical and structural property are discussed in view of infrared spectroscopy and FT-IR, XPS, which shows increasing C-O bonding and C-C bonding. The root mean square of surface roughness examined by means of AFM changed smoothly from 0.387nm to 0.207nm and the change of wettability was discussed with respect to elastic and inelastic collisions obtained as results of TRIM simulation. It was found that wettability of the modified PC surface was affected on change of functional group and nuclear stopping or linear energy transfer(LET, energy deposited per unit track length per ion) that causes chain scission by displacing atom from polymer chains, but was not greatly dependant on surface morphology.

• Membrane and Water Treatment
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• 제10권2호
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• pp.113-120
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• 2019

To investigate surface properties and interception performances of the new modified PVDF membrane coated with Graphene Oxide (GO) and nano-$TiO_2$ (for short the modified membrane) via the interface polymerization method combined with the pumping suction filtration way, filtration experiments of the modified membrane on Humic Acid (HA) were conducted. Results showed that the contact angle (characterizing the hydrophilicity) of the modified membrane decreased from $80.6{\pm}1.8^{\circ}$ to $38.6{\pm}1.2^{\circ}$. The F element of PVDF membrane surface decreased from 60.91% to 17.79% after covered with GO and $TiO_2$. O/C element mass ratio has a fivefold increase, the percentage of O element on the modified membrane surface increased from 3.83 wt% to 20.87%. The modified membrane surface was packed with hydrophilic polar groups (like -COOH, -OH, C-O, C=O, N-H) and a functional hydrophilic GO-polyamide-$TiO_2$ composite configuration. This configuration provided a rigid network structure for the firm attachment of GO and $TiO_2$ on the surface of the membrane and for a higher flux as well. The total flux attenuation rate of the modified membrane decreased to 35.6% while 51.2% for the original one. The irreversible attenuation rate has dropped 71%. The static interception amount of HA on the modified membrane was $158.6mg/m^2$, a half of that of the original one ($295.0mg/m^2$). The flux recovery rate was increased by 50%. The interception rate of the modified membrane on HA increased by 12% approximately and its filtration cycle was 2-3 times of that of the original membrane.

• 한국미생물·생명공학회지
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• 제15권2호
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• pp.122-128
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• 1987

Candida rugosa와 Rhizopus arrhizus 리파제를 photocrosslinkable resin prepolymer에 고정화시켜서 이소옥탄을 유기용매로 사용한 이상계를 이용해서 유지분해 및 에스테르교환 반응을 보고자했다. Dioctylsulfosuccinate가 가장 좋은 surfactant였다. 소수성 젤인 ENTP-3000에 고정된 리파제가 좋은 활성을 나타냈고 친수성 젤인 ENT-4000에 고정된 리파제가 유기용매에 대해 안정했다. 고정화 matrix의 소수성이 증가될수록Vm(app)는 증가되었으나 Km(app)는 거의 일정했다. 리파제의 최적 pH는 소수성 젤인 ENTP-3000에 고정된 경우 C. rugosa와 R. arrhizus 리파제에 대해서 각각 6.0과 6.5였으나, 친수성 젤에 고정된 리파제는 짧은 시간 반응에는 pH에 크게 영향을 받지 않았으나 긴 시간 동안 반응시킬 때는 역시 pH6.0과 6.5에서 각각 C. rugosa와 R. arrhizus 리파제가 높은 양의 지방산을 분해시켰다. 리파제를 entrapment 시키면 열안정성이 증가됨을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.165-165
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• 2014

In this study, we demonstrated that the soft lithographic patterning processing of chemical vapor deposition (CVD) graphene and rGO sheets as large scale, low cost, high quality and simplicity for future industrial applications. Recently, a previous study has reported that single layer graphene grown via CVD was patterned and transferred to a target surface by controlling the surface energy of the polydimethylsiloxane (PDMS) stamp [1]. Using this approach, the surface of a relief-patterned elastomeric stamp was functionalized with hydrophilic dimethylsulfoxide (DMSO) molecules to enhance the surface energy of the stamp and to remove the graphene-based layer from the initial substrate and transfer it to a target surface [2]. Further, we developed a soft lithographic patterning process via surface energy modification for advanced graphene-based flexible devices such as transistors or simple and efficient chemical sensor consisting of reduced graphene oxide (rGO) and a metallic nanoparticle composite. A flexible graphene-based device on a biocompatible silk fibroin substrate, which is attachable to an arbitrary target surface, was also successfully fabricated.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.300-305
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• 2000

We have investigated the dielectric and electrical characteristics of palmitic acid(PA) stearic acid(SA) and arachidic acid(AA) Langmuir-Blodgett(LB) films because these fatty acid systems have a same hydrophilic group and a different hydrophobic one(methylene group or alkyl chain length). The fatty acid systems were used as LB films and the status of the deposited films was confirmed by evaluating the transfer ratio the UV absorption and the capacitance. The dielectric characteristics such as the frequency-capacitance characteristics and the dielectric dispersion and absorption characteristics of PA SA and AA through-plane were measured. The relative dielectric constants of PA, SA and AA LB films were about 3.0~4.6, 2.7~3.0 and 2.4~3.0 respectively. That is the relative dielectric constants were decreased in proportion to the chain length of methylene group. Also the dielectric dispersion and absorption of each fatty acid LB films have arisen from spontaneous polarization of dipole polarization in the range of 10$^4$~10$^{5}$ ［Hz］. The conductivity of PA, SA and AA LB films obtained from I-V characteristics were about 9$\times$10$^{-14}$ , 3$\times$10$^{-14}$ and 5$\times$10$^{-15}$ ［S/cm］. respectively. These results have shown the insulating materials and could control the conductivity y changing the length of methylene group. Also we have confirmed that the barrier height of fatty acid systems were almost the same ones obtained from dielectric characteristics.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권1호
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• pp.13-18
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• 2000

We have fabricated LB ultra-thin films of maleate system by LB technique and evaluated the deposited status of LB ultra-thin films by I-V characteristics such as capacitance. It was found that the thickness of LB ultra-thin per layer is $27~30[{\AA}]$ by XRD. And, we have known that the conductivity along the horizontal direction of LB ultra-thin films was about $10^{-8}[S/cm]$, it corresponds to the semiconducting materials. Also, the I-V characteristics along the vertical direction of LB ultra-thin films was dominated by Schottky type current, the activation energy obtained by current-temperature characteristics was about 0.84[eV] and the conductivity was about $10^{-14}[S/cm]$, it corresponds to the insulator. And, the anisotropic conduction mechanism of the LB ultra-thin films in vertical direction and horizontal direction is determined by the hydrophilic group and the hydrophobic group in LB ultra-thin films. The above results are applicable to the semiconductor devices such as switching device, which function at the molecular level.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.37-46
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• 1995

The substitution of carboxymethylated hydroxyl group in pulp revealed more hydrophilic than hydroxyl group. And then fibers were more flexible, swell more which leads to better conformation between fibers in turn this raise paper strength. In this paper, we tried to chemical modifyings of recycled fiber, OCCs(old corrugated containers). Many researchers have examined chemical modification of papermaking fiber by partial carboxymethylation(PCM) using a organic solvent processes. We made modified PCM processes adapted waters m replace of the organic solvent. Our testings for the optimum conditions on the new method, conditions as reaction time, temperature, liquor ratios were designed likely plant system. Freenesses(SR$^{\circ}$) were increased following on carboxyl content of the samples. Handsheets of untreated samples and partial carboxymethylated OCCs were made by optimum conditions on different concentrations of the reagent. As results, maximum 25% strength increasing effects were obtained by the new method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.349-352
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• 1999

We have investigated the electrical characteristics of arachidic acid($C_{20}$), stearic acid(C_{18} and palmitic acid($C_{16}$) Langmuir-Blodgett(LB) films because the fatty acid systems have a same hydrophilic group and a different hydrophobic one (alkyl chain length). In this work, fatty acid systems were used as LB films and the status of the deposited films were confirmed by evaluating the capacitance and I-V characteristics. The conductivity of $C_{20}$, C_{18} and $C_{16}$ LB films obtained from I-V characteristics were about 5x $10^{15}$, 3x $10^{14}$ and 9x $10^{14}$[S/cm], espectively. These results have shown the insulating materials and could control the conductivity by changing the length of alkyl chain. Also, we have confirmed that the barrier height of fatty acid systems were about 1.32- 1.40[eV] and the relative dielectric constant were about 2.9~4.2. These values were almost the same ones obtained from dielectric characteristics.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권1호
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• pp.15-22
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• 2015

Poly(ethylene glycol) end-capped with pentafluorophenyl group(s) in ABA (FP-PEG-FP) and AB (mPEG-FP) types were prepared. Even though they were similar in composition, the lower critical solution temperature (LCST) of FP-PEG-FP was observed at $23^{\circ}C$, whereas that of mPEG-FP was observed at $65^{\circ}C$. To understand the large difference in solution behaviour of the two polymers, UV-VIS spectroscopy, microcalorimetry, 1H-NMR spectroscopy, and dynamic light scattering were used. FP-PEG-FP has two hydrophobic pentafluorophenyl groups at the ends of hydrophilic PEG (1000 Daltons), whereas mPEG-PF has a highly dynamic PEG (550 Daltons) block that are anchored to a hydrophobic pentafluorophenyl group. PF-PEG-PF not only has a smaller conformational degree of freedom than mPEG-PF but also can form extensive intermolecular aggregates, therefore, PF-PEG-PF exhibits a significantly lower LCST than mPEG-PF. This paper suggests that topological control is very important in designing a temperature-sensitive polymer.