• Elastomers and Composites
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• v.42 no.2
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• pp.75-85
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• 2007

In this study, the new adhesion system was studied to improve the adhesion strength between polyester cord and rubber matrix. In order to enhance the adhesion strength through polyester cord's surface treatment, the NaOH solution was used. The NaOH solution concentrations of 0.03, 0.05, 0.1, 0.2, 0.5, 1 and 5 wt.% were used in surface modifying the polyester cord. The optimum condition showing the maximum adhesion strength of polyester cord with SBR compound containing bonding agent was at NaOH concentration of 0.05 wt.% with treatment time of 10 minutes. When the NaOH solution concentration was above 1 wt.%, the polyester cord due to the excess surface modification was damaged, and resulted in breakage during the adhesion test. Also, the adhesion strength between polyester and SBR could be improved by coating the polyester cord with triallylcyanurate(TC) adhesive. The drying condition of polyester cord coated with TC attributed to the adhesion strength. The maximum adhesion strength was obtained by using the polyester cord dried at $220^{\circ}C$ rather than dried at room temperature.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.1
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• pp.64-78
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• 2011

Surface of hydrophobic polyethylene membrane was modified to become hydrophilic by ion beam irradiation. Submerged membrane filtration reactors contained pristine membrane or surface-modified membrane and the influent to reactors was pickled radish wastewater. The objectives of this study was to investigate the variation of flux and pressure and the characteristics of pollutant removal such as organics, suspended solids and nutrients with time. The result of experiments using intermittent pristine membrane showed the occurrence of severe fouling by increasing permeate pressure rapidly in case of pickled radish wastewater but in synthetic wastewater, this phenomenon was not occurred. In experiments of variation flux after chemical cleaning and water cleaning in pristine membrane, chemical cleaning must be necessary for renewals of pollutant membrane. Performance of intermittent operation is higher than that of continuous operation. Reaching fouling time in the case of surface-modified membrane is 6 times as long as pristine membrane. According this reason, replacement expense of surface-modified membrane could be 1/6 of that of pristine membrane. Effluent from this process was relatively good water quality and performance in the removal efficiency of SS, nitrogen and phosphorus was particularly higher.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.322-327
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• 1987

$ZrO_2$was modified by treating with $H_2SO_4$ and by treating witb $SO_2,\;H_2S,\;and\;CS_2$ followed by oxidation. The oxidized species and oxidation state of sulfur compounds were investigated by infrared and X-ray photoelectron spectroscopies. The generation of strong acidity of modified $ZrO_2$ was independent of the sulfur source after oxidation. The sulfur ($SO_4{^{2-}}$) in the highest oxidation state was responsible for the superacidic property of the modified $ZrO_2$.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.66-70
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• 2007

현재 많은 연구들이 작은 크기에 여러 공정을 집적시킬 수 있는 장점을 가진 마이크로 장치의 개발과 활용에 집중되고 었다. 마이크로 장치에서 가장 중요한 것은 미세 유동의 효율적인 제어이다. 본 연구에서는 마이크로 장치에 직접 적용 가능한 표면 개질 된 마이크로 채널의 유동에 대하여 고려하였다. 표면 개질(surface treatment)은 물리적, 화학적인 작용을 통해서 채널 내부 표면의 습윤성을 변화시켜 유동을 제어하는 방법이다. 친수성(glass)을 가지는 마이크로 채널 내부의 일부를 소수성(teflon)으로 개질 후, 고속카메라를 이용하여 채널 내부를 흐르는 유체의 유동 경계면 변화를 분석하였다. 또한 유동 해석을 위한 상용 코드(CFD-ACE)를 이용하여 유동에 대한 수치 해석을 진행하여 가시화된 실험 결과와 비교 분석하였다. 실험 결과와 수치 해석 결과를 통해, 친수성과 소수성 표면 배열에 따른 일시적인 유동 변화를 관찰하였다. 본 연구 결과를 통해 마이크로 채널 유동의 최적화 상태를 찾을 수 있으며, 보다 용이한 미세 유동 제어가 가능하다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.261-269
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• 2015

In this study, numerical analysis of curved channel steam-methanol reformer was conducted using the computational fluid dynamics (CFD) commercial code STAR-CCM. A pre-numerical analysis of reference model with a cylindrical channel reactor was performed to validate the combustion model of the CFD commercial code. The result of advance validation was in agreement with reference model over 95%. After completing the validation, a curved channel reactor was designed to determine the effects of shape and length of flow path on methanol conversion efficiency and generation of hydrogen. Numerical analysis of the curved-channel reformer was conducted under various flow rate ($10/15/20{\mu}l/min$). As a result, the characteristics of flow and mass transfer were confirmed in the cylindrical channel and curved channel reactor, and useful information about methanol conversion efficiency and hydrogen generation was obtained for various flow rate.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.81-90
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• 2010

This paper describes the results of laboratory and field performance tests on the polymer modified asphalt binder and mixtures developed in this study for porous asphalt pavements. Various physical and mechanical laboratory tests including DSR and BBR tests are performed for two types of modified binders, and one type of binder is selected based on the binder testing results. Mix designs are conducted for the selected asphalt binder and a Japanese modified binder, respectively. Various performance tests including fatigue tests, wheel tracking tests, and moisture susceptibility tests are conducted for the domestic and Japanese porous asphalt mixtures. Test results indicate that the overall performance characteristics of the domestic mixture are similar to or better than those of the Japanese mixture. Based on the laboratory testing results, the domestic porous mixture is applied to a field test section. Periodic field investigations are conducted to evaluate the changes in noise level and air voids with time. The road noise analysis shows that the noise levels of the porous pavement keep increasing and, after two years, are similar to those of SMA pavements.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.153-160
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• 2009

Falling Weight Deflectometer (FWD) tests were performed to evaluate the structural capacity of glass fiber reinforced (GFR), polymer modified (PM), and unmodified asphalt pavement in Korea-LTPP (Long Term Pavement Performance) section. FWD tests showed that the tensile strains of GFR and PM asphalt pavements at the bottom of asphalt layer were 29% and 21% less than that of unmodified asphalt pavement. The structural capacity was then used as a performance criterion for calculating the cost effect of GFR and PM asphalt pavements. From the results, 5cm of asphalt layer thickness was reduced by applying GFR asphalt, and 3cm by applying PM asphalt. However, construction cost of PM and GFR asphalt pavement were increased due to the higher GFR and PM asphalt price. Life cycle cost analysis showed that the initial construction cost of GFR and PM asphalt pavement were higher but the management and user cost were less than those of unmodified asphalt pavement.

• Membrane Journal
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• v.28 no.3
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• pp.169-179
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• 2018

The purposes of this paper were to improve both fouling and chlorine resistance by increasing the hydrophilicity of the reverse osmosis membrane. In order to improve chlorine resistance, the surface of RO membrane was activated by ultraviolet irradiation, and then it was modified by the sol-gel method using Octyltriethoxysilane (OcTES) such as the silane coupling agent to low sensitivity to chlorine, thereby the polyamide active layer was protected and chlorine resistance was improved. In addition, polyglycerol polyglycidyl ether (PGPE) and sorbitol polyglycidyl ether (SPE) coating with different number of epoxides, ring opening reaction of epoxide improved the anti-fouling resistance. The surface modification condition was optimized by FT-IR, XPS, and contact angle analysis. As a result, the permeability reduction rate of the silane-epoxy modified membrane after the fouling test was decreased about 1.5 times as compared with that of the commercial membrane. And the salt rejection was maintained over 90% at $20,000ppm{\times}hr$ even after chlorine resistance test.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.121-121
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• 2017

본 연구는 비전도성 폴리머 표면을 개질하여 감광성 금속을 유전체 표면에 흡착시키고, 감광성 금속의 광화학 반응을 이용하여 귀금속 촉매를 비전도성 폴리머 표면에 선택적으로 흡착시켜 무전해 Cu 도금을 수행하여 금속패턴을 형성하였다. 기능성 유연 필름은 일반적으로 투명한 플라스틱 고분자 기판을 기반으로 전기 전자, 에너지, 자동차, 포장, 의료 등 다양한 분야에서 폭넓게 활용 되고 있으며, 본 연구에서는 습식 도금 공정을 이용하여 폴리이미드 필름상에 $10{\mu}m$ 이하의 미세패턴을 형성하기 위한 공정을 개발하고자 하였다. 비전도성 폴리머 표면에 무전해 도금을 위해서 우선 폴리머 필름의 표면을 개질하는 공정이 필요하다. 이에 KOH 또는 NaOH 알카리 용액을 이용하여 표면을 개질하였으며 개질된 표면에 감광성 금속이온의 흡착시키기 위한 감광성 금속이온은 주석을 사용하였으며, 주석 용액의 안정성 및 퍼짐성 향상을 위해 감광성 금속 용액의 제조 및 특성을 관찰하였으며, 감광성 금속화합물이 흡착된 비전도성 유전체 표면을 포토마스크를 이용하여 특정 부위, 즉 표면에 금속패턴 층을 형성하고자 하는 곳은 포토마스크를 이용하여 광원을 차단하고 그 외 부분은 주 파장이 365nm와 405nm 광원을 조사하여 선택적으로 감광성 금속화합물의 산화반응을 유도하는 광조사 공정을 수행하였다. 광원이 조사되지 않은 부분에 귀금속 등의 촉매 입자를 치환 흡착시켜 금속 패턴이 형성될 수 있는 표면을 형성하였다. 위의 활성화 공정이후에 활성화 처리된 표면을 세척하는 수세 공정을 거친 후 무전해 도금공정에 바로 적용할 경우 미세한 귀금속 입자가 패턴이 아닌 부분 즉 자외선(UV) 조사된 부분에도 남아있어 도금시 번짐 현상이 발생한다. 이에 본 연구에서는 활성화 처리 후 약 알칼리 용액에 카르복실산을 혼합하여 잔존하는 귀금속 입자를 제거한 후 무전해 Cu 도금액을 이용하여 $10{\mu}m$ 이하의 Cu 금속 패턴을 형성하였다.

• Journal of Adhesion and Interface
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• v.4 no.4
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• pp.22-27
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• 2003

Chemical modification of carbon nanotube (CNT) was carried out using $HNO_3$ and $H_2SO_4$ and characterized by analyzing the CNT before and after the modification using FT-IR and titration. Aggregation behaviors were investigated using a real-time video microscope after the chemically modified CNT(mCNT) had been dispersed in organic solvents such as toluene, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) by ultrasonication. The mCNT showed better dispersion in polar sovents of DMF and NMP than the rCNT. CNT/ poly(methylmethacrylate) (PMMA) films were prepared from solution DMF/PMMA solutions. The films containing mCNT also revealed the improved dispersion.