• 상하수도학회지
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• 제32권5호
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• pp.453-460
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• 2018

The impact of sodium hydroxide, which is one of chemicals of clean in place (CIP) for removing membrane fouling, on the PVDF membrane is reviewed with respect to physical/chemical structural change, the permeability affected therefrom. Based on the cleaning concentration applied in membrane water treatment facilities, 10% of accumulated defluorination was confirmed up to 166g.hr/L which reflects the exposure time. However, membrane resistance was confirmed to be reduced by about 10%. Through FT-IR and EDS analysis, reduction of F and change of are confirmed as factors that affect the permeability of membrane. Membrane resistance, which affects permeability, is affected by loss of additives for hydrophilicity, rather than defluorination of PVDF material. Therefore, in order to check membrane degradation degree, an accelerated test by NaOH was carried out, loss of additives was confirmed, and then PVDF inherent characteristic was observed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.391-396
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• 2005

Salt water spray test and salt water immersion test were experimentally conducted in order to investigate the durability of fiber reinforced composites under salt water environment. The specimens were made of glass fabric reinforcement and phenolic resin. Mechanical test was performed to obtain mechanical properties such as tensile properties, flexural properties, and shear properties by varying with exposure times. Also dynamic mechanical test and FTIR were conducted to investigate a change in chemical structure as well as thermal analysis properties such as storage shear modulus, loss shear moduls, and tan ${\delta}$. According to the results, salt water environment has effected on mechanical properties and thermal analysis properties and especially the durability of glass fabric/phenolic composites were severely affected on salt water immersion environment rather than salt water spray environment.

• Bulletin of the Korean Chemical Society
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• 제26권3호
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• pp.413-417
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• 2005

Fluorescence of green fluorescent protein mutant, 2-5 GFP is observed during denaturation by guanidine. The fluorescence intensity decreases exponentially but the fluorescence lifetime does not change during denaturation. The fluorescence lifetime of the denatured protein is shorter than that of native form. As the protein structure is modified by guanidine, solvent water molecules penetrate into the protein barrel and protonate the chromophore to quench fluorescence. Most fluorescence quenchers do not affect the fluorescence of native form but accelerate the fluorescence intensity decay during denaturation. Based on the observations, a simple model is suggested for the structural change of the protein molecule during denaturation.

• 한국응용과학기술학회지
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• 제20권1호
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• pp.27-32
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• 2003

The core-shell latex particles were prepared by sequential emulsion polymerization of alkyl methacrylate and styrene(ST) by using an water-soluble initiator(APS) after preparing monomer pre-emulsion in the presence of an anionic surfactant(SDBS). In organic/organic core-shell polymerization, the pre-emulsion method, which minimized required quantity of sulfactant, has been used to increase the conversion rate and the stability of core-shell latex particles as well as to reduce the formation of secondary particle that cause problems of soap-free emulsion during shell polymerization. We used several methods to observe the core-shell structure. The core-shell structure was studied by measuring pH change during hydrolysis by NaOH, glass transition temperature($T_g$) by differential scanning calorimeter(DSC), morphology of latex by transmission electron microscope(TEM) and change of particle size and distribution by a particle analyzer.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1998년도 봄 학술발표회 프로그램
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• pp.109-111
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• 1998

A sensor was designed to detect backmixing of vessel fluid into the feedpipe. The sensor was composed of electrodes and a designed electric circuit. The electrodes were installed inside the feedpipe and tap water was flowed into the feedpipe. When NaC1 solution in the vessel penetrate into the feedpipe due to high agitator speed, the conductivity change is sensed by the electrodes and the resultant output signal is recorded by a pen-chart recorder. The electric circuit was designed to show maximum sensitivity. The resolution of this designed sensor was on the order of 10-s mole/l.

• 한국임상수의학회지
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• 제15권1호
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• pp.75-78
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• 1998

This study was performed to estimate the clinical signs and changes of biochemical parameters in rats with hepatic injury induced by the administration of 2, 2'-azobis(2- amidinopropane)dihydrochloride (AAPH) . Minor behavioral change, brittleness of skin hair and decreased volume of water and feed intake were observed in ra% 2 hours after AAPH administration compared to control group. Concentration of serum albumin showed lower than that of control group. However, concentration of total bilirubin has shown higher than that of control group. As time goes on, . serum LDH activity increased significantly compared to control group, but senun CPK activity did not change compared to control group. Passive hemanglutination of $\alpha $-fetoprotein was negative in all the treaDent groups and control group.

• 동아시아식생활학회지
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• 제13권6호
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• pp.601-607
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• 2003

This study was attempted to investigate the physicochemical changes during soybean-leaf water kimchis fermentation by adding wheat flour in cooking water. Soybean-leaf water kimchis with five different levels of wheat flour in cooking water(0%;A, 5%;B 10%;c, 15%;D, 20%;E) were tested for rhological parameters, fine structural changes, sensory evaluations and chemical analysis. The composition of the soybean-leaf was moisture (80.9%), protein(6.8%), fat(0.6%), ash(2.1%) and alkalinity (+14.9). The amount of reducing sugars of sample A and other samples were 0.75% and 1.08∼1.4% in the initial fermentation stage, but decreased to 0.3 and 0.43∼0.50% in the later fermentation stage, respectively. The pH of sample A decreased from 5.17 to 4.72 during the initial fermentation. On sample B, C, D and E, pH's decreased rapidly during the initial fermentation, but they did not change much in the later fermentation stage. The pectin contents of all samples decreased during 2nd and 4th day of fermentation, then the change was slow. The amount of hemicellulose. cellulose and lignin in terms of the DNF and ADF were varied from 4 to 33%, but the contents of them did not greatly changed during the fermentation. The sensory evaluation showed that both B and C samples had the good score in sweety taste, roasted nutty taste, and the ease of swallowing measured as chewiness. From these results, the optimum soybean-leaf water kimchis can be prepared when 200g soybean-leaf, 1000$m\ell$ water, 15g garlic, 3% red pepper powder and 5 ∼0% wheat flour were fermented at 20$^{\circ}C$ for 2 days.

• 한국의류학회지
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• 제29권3_4호
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• pp.561-568
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• 2005

The irradiation of Ultra-Violet (UV) is an efficient treatment for polymer to improve hydrophilic properties. 4-Channel PET knit fabrics were treated with UVA and UVC to develop functional and environment-friendly fabric. The fabric was treated with various treatment times and distances from UV lamps having different wavelength. FT-IR and XPS investigated the chemical changes. To confirm the change of surface properties, contact angle, surface energy and SEM were examined. The study of UV as a treatment for PET knit fabric shows significant changes in chemical and surface properties, which is proved by analyses. FT-IR and XPS analyses prove the augmentation of carboxylic, Hydrophilic groups on the surfaces treated by UV. The increase of water contact angle and surface energy means more water wettable and surface energy of PET film was substantially increased by UV irradiation time. The ageing after surface treatment had little influence on the surface energy of the irradiated PET film. SEM proves the surface modification of PET such as etching, bubble and crack. The negative effects are increased in accordance with increasing treatment time.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.825-829
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• 2012

본 연구에서는 전기분해 처리된 해수의 유효염소농도와 온도에 의한 배가스 중 NO의 산화 특성을 실험적으로 살펴보았다. 실험은 무격막식 전해수가 채워진 버블링 반응기에 반응가스를 공급하여 NO 농도의 변화를 분석하였다. 폐순환 전기분해 시스템의 경우 정전류 조건에서 전해 시간이 길어질수록 전해수 내에 유효염소농도가 상승하였고, 전해수의 유효염소농도가 높을수록 NO가 $NO_2$로 산화되는 반응이 촉진됨을 확인하였다. 또한 동일한 유효염소농도를 가지는 전해수의 경우에도 온도가 높을수록 NO 산화율이 증가하였다.

• Korean Chemical Engineering Research
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• 제43권1호
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• pp.66-70
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• 2005

IS 프로세스의 HI 분해 반응에서의 적용을 위해 고분자재료(폴리이미드)를 이용하여 탄화 막을 제작하고, 이 탄화막에 SiO를 처리함으로써 SiC 막을 제작하였다. 폴리이미드의 탄화에 의한 중량 감소는 약 50% 정도이고, 탄화 온도가 증가할수록 중량감소도 증가하였다. 탄화막은 탄화온도가 상승하면 가스 투과속도가 감소하고 막의 치밀화가 진행되었다. SiC 막은 SiO의 처리 농도가 증가하면 가스 투과 속도는 증가하고, 기체 투과 메커니즘은 활성화에너지 흐름에서 Knudsen 흐름으로 변화한다는 것을 알 수 있었다.