• 한국막학회:학술대회논문집
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• 한국막학회 1994년도 추계 총회 및 학술발표회
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• pp.62-63
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• 1994

The membrane technology is more convenient and economical way in the separation field than conventional technology such as distillation, extration, crystallization, and so on. Therefore, membrane are used as efficient tools for the separation and concentration of molecular mixture in many industrial area. Although the polymeric membrane have various advantage, they have disadvantages as well. One of them is a poor resistance to organic solvent. Therefore, organic solvent resistant membranes were prepared by soluble polyimide. prepared by phase inversion method. The membranes were The homogeneous polymer solutions were obtained by the two different method ; the one is that the polymer sythesized was completely dissolved in a solvent to prepare a membrane casting solution, the other is that a membrane casting solution was prepared by the unit process from the viscose solution of polymerization.

• Carbon letters
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• 제23권
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• pp.55-62
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• 2017

We report on the dispersion state of partially reduced graphene oxide (PRGO) in organic solvents, namely methyl ethyl ketone, ethyl acetate, methylene chloride, toluene, and xylene, by controlling the carbon to oxygen (C/O) atomic ratio of the PRGOs. A two-phase solvent exchange method is also proposed to transfer PRGO from water to an aprotic solvent, such as methyl ethyl ketone. We achieve relatively good dispersion in aprotic and non-polar solvents by controlling the C/O atomic ratio of the PRGOs and applying the two-phase solvent exchange method. There is an increase in the glass transition temperatures with the dispersion of PRGOs into amorphous polymers, in particular a $4.4^{\circ}C$ increase for poly(methyl methacrylate) and $3.0^{\circ}C$ increase for polycarbonate. Good dispersion of PRGO in a nonpolar polymer, such as linear low density polyethylene, is also obtained.

• KSBB Journal
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• 제26권5호
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• pp.453-458
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• 2011

In this study, two different extraction techniques, organic solvent extraction and supercritical carbon dioxide ($SCCO_2$) extraction, were employed to evaluate the extraction efficiency of oil from Chlorella vulgaris. In the organic solvent extraction, the effects of various organic solvent on the extraction yield were investigated. The $SCCO_2$ extraction was carried out while varying such operating parameters as temperature, pressure, $SCCO_2$ flow rate, and cosolvent. About 4.9 wt% of oil was extracted from ground Chrollera vulgaris for 18 h when dichloromethane/methanol (2：1, v/v) was used as an extraction solvent. The oil yield of the $SCCO_2$ extraction was found to be very low (0.53 wt%) and to increase up to about 0.86 wt% with the addition of cosolvent.

• Journal of Preventive Medicine and Public Health
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• 제31권4호
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• pp.628-643
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• 1998

To investigate the exposure levels of organic solvents and subjective symptoms of dry-cleaning workers, 77 male and 52 female dry-cleaning workers who had been worked in a small city of Chungnam province, and a large city, Taejon were selected for the study group. Air concentrations of organic solvents in the working environment were analyzed, and subjective symptoms of dry-cleaning workers were surveyed, from July to August 1996. The results obtained were as follows : 1. The concentrations of organic solvents in the working environment were within permissible TLV-TWA limits. 2. For the 13 symptom clusters, the most frequently complained symptom clusters were fatigue as 71.3%, and followed by depression and urinary disturbances as 53.5% and 51.9%. Other symptom clusters complained were below 50%. 3. Positive response rates of subjective symptoms were significantly higher in worker groups such as lived in a large city, female, higher education level, more frequently alcohol drinking, higher concentration of organic solvent in working environment, work in alone. 4. Workers who had used solvent B showed 2.3 point higher scores of subjective symptoms than those of solvent A. Of the subjective symptoms scores, amnesia and nervousness were higher in solvent B user group than solvent B user group. 5. As a result of factor analysis, 3 factors such as depression, urinary disturbance and neurologic disturbance were selected. 6. As a result of the logistic regression analysis, sex, the number of fellow workers, working time, region, job tenure, smoking, alcohol drinking, ventilating system, concentration of organic solvent in working environment and place of residence were selected for the related variables. For the conclusion, even though the concentrations of organic solvents in the working environments of dry-cleaning workers were within permissible limit of TLV-TWA, many dry-cleaning workers complained symptoms, such as fatigue, depression, urinary disturbances and so on. And the factors affecting to the symptoms of dry-cleaning workers were the number of fellow workers, work hours, region, job tenure, smoking and alcohol drinking.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.342-342
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• 2006

Atomic force microscope (AFM) enables us to stretch a single polymer chain by picking it at its two modified termini. Using this method called "nanofishing," we have studied statistical properties of single polymer chains. A force-extention curve obtained for a polystyrene with thiol termini in a cyclohexane showed a good agreement with a worm-like chain (WLC) model, and thus gave microscopic information about entropic elasticity. In this report, the experiments were performed at wide-range temperatures, resulting in wide-range solvent qualities from poor to good solvent condition. The temperature dependence of statistical properties of polystyrene was examined. The coil-strand transformation realized in a poor solvent was also discussed.

• 한국세라믹학회지
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• 제33권2호
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• pp.214-222
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• 1996

The effect of physicochemical properties of organic solvent and dispersant among organic solvent dispersant binder and plasticizer which are used as processing additives in MLCC fabrication process on the dispersion of BaTiO3 was studied. The steric and electrostatic stabilization mechanisms in dispersion of BaTiO3 in organic media were evaluated respectively. The sttability of BaTiO3 achieved bysteric stabilization was dependent on the fraction of surface coverage of dispersant adsorption on BaTiO3. The electrostatic repulsive forces of BaTiO3 particles dispersed in orgainc media was found to be appreciabley great and dependent mainly on the kinds of organic solvent used. The mechanism affecting the stability of BaTiO3 was studied by the method of rheologi-cal behaviors of BaTiO3 suspension.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.490-493
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• 2003

Enzymatic synthesis of sugar fatty acid esters was investigated in organic solvent using Candida rugosa lipase. To overcome sugars insolubility in organic solvent, sugar absorption procedure was done on a silica gel. The product yield was determined by using ion Chromatography, with various factors such as reaction time, enzyme fatty acid molar ratio, number of carbon in fatty acid.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4167-4170
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• 2011

An inexpensive and efficient catalyst system has been developed for the N-arylation of phenylurea including a variety of aryl halides. This simple protocol uses $Cu_2O$ as the catalyst, microwave assisted, solvent- and ligand-free, $K_3PO_4{\cdot}H_2O$ as the base.

• 자원리싸이클링
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• 제11권6호
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• pp.38-46
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• 2002

분별증류법을 이용하여 폐유기용제를 회수하는 과정의 평형 및 반응 속도론적인 면에 대한 기초연구를 수행하였다. 산업용 유기용제로 가장 많이 사용되고 있는 toluene과 xylene으로 인공폐용제을 제조하였다. 증류된 용제의 순도를 GC를 이용하여 검증해 본 결과 회수율은 94～98% 범위로 매우 양호하였다. 평형론적 해석을 통해 증류반응에 대한 Gibbs 자유 에너지의 변화와 표준 엔탈피 및 표준 엔트로피의 변화를 산정하였으며 toluene과 xylene의 표준 엔탈피 변화값이 각각 44.833과 47.044kJ $mol^{-1}$ 로 이들 물질의 몰증발열과 유사한 값을 나타내었다. 한편 반응 속도론적으로 해석해 본 결과 증류반응에 대한 활성화에너지는 toluene이 3.281kJ $mol^{-1}$ 로 xylene의 2.699kJ $mol^{-1}$ 보다 다소 높았으며 이는 표준 엔탈피 변화값과 비교해 볼 때 평형시에 비해 증류중 에너지 소비가 십분의 일 수준임을 파악할 수 있었다. 분별증류로 회수한 용제의 순도 역시 우수하여 회수한 폐용제가 원용제를 부분적으로 대체할 수 있는 가능성이 있음을 확인할 수 있었다.

• Journal of Microbiology
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• 제44권6호
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• pp.583-590
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• 2006

In this study, an organic solvent tolerant bacterial strain was isolated. This strain was identified as Pseudomonas sp. strain S5, and was shown to degrade BTEX (Benzene, Toluene, Ethyl-Benzene, and Xylene). Strain S5 generates an organic solvent-tolerant lipase in the late logarithmic phase of growth. Maximum lipase production was exhibited when peptone was utilized as the sole nitrogen source. Addition of any of the selected carbon sources to the medium resulted in a significant reduction of enzyme production. Lower lipase generation was noted when an inorganic nitrogen source was used as the sole nitrogen source. This bacterium hydrolyzed all tested triglycerides and the highest levels of pro-duction were observed when olive oil was used as a natural triglyceride. Basal medium containing Tween 60 enhanced lipase production to the most significant degree. The absence of magnesium ions ($Mg^{2+}$) in the basal medium was also shown to stimulate lipase production. Meanwhile, an alkaline earth metal ion, $Na^+$, was found to stimulate the production of S5 lipase.