• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.353-356
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• 2001

The relation between the flocculation and dispersion of metal oxide powders and the properties of solvents, such as dielectric constant and solubility parameter, was investigated for TiO$_2$, $Al_2$O$_3$and Fe$_2$O$_3$particles. The particle size and median diameter of these metal oxides were measured in many organic solvents, from which the effect of solvents on the flocculation and dispersion of metal oxide powders was considered. The metal oxide powders of TiO$_2$, $Al_2$O$_3$and Fe$_2$O$_3$tend to disperse in a solvent of higher polarity, whereas they are apt to flocculate in a solvent of low dielectric constant, because the Hamaker constant between the particles becomes larger in such a solvent. There we, however, some solvents that do not obey these tendencies. It is possible to evaluate the flocculation and dispersion of these metal oxide powders in many solvents by using numeral balances of Hansen’s three-dimensional solubility parameter (f$_{d}$, f$_{p}$ and f$_{h}$). There exists a solvent giving the optimal dispersion for each metal oxide, and the optimal dispersion point of f$_{d}$, f$_{p}$ and f$_{h}$ is determined by the combination of various metal oxide powders and solvents.nts.nts.nts.

• Toxicological Research
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• 제17권1호
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• pp.7-9
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• 2001

The quantitative assessment of the penetration of organic solvents through skin is necessary for the evaluation of health hazards in occupational environments. We investigated the rate of dermal penetration when mixed or single forms of organic solvents were placed into a diffusion cell in vitro or into an experimental animal in vivo. The diffusion rates of methanol. toluene, and styrene were 6.07, 0.129, and 0.046 mg/$cm^2$/h, respectively. When skin was exposed to the mixed solvent of methanol and toluene, the penetration rate of toluene did not change significantly (0.110 mg/$cm^2$/h). However, the rate of methanol penetration increased to 43.90 mg/$\textrm{cm}^2$/h. The penetration rate of methanol also increased significantly to 54.69 mg/$cm^2$/h by mixing it with styrene. The concentration of methanol in the blood was monitored during the epicutaneous exposure in rats. The blood concentration of methanol was increased by mixing methanol with toluene as seen in the in vitro experiments. These results showed that the penetration rate of organic solvents would be enhanced by mixing them with other solvents.

• Archives of Pharmacal Research
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• 제3권1호
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• pp.1-6
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• 1980

As part of our endeavor to increase the productivity of steroid by enzymatic transformation of corticosteroids, attempts have been made to increase the solubility of steroids by using some organic solvents. When the solubility of steroids is the rate limiting factor in the steroid transformation, it was found that the use of solvents significantly improved the yield. Hydrocorisone as a substrate and 3-ketosteroid .DELTA.$^{1}$ dehydrogense as an immobilized whole cell enzyme were employed as the model system for this study. It was found that the yield of product, prodnisolone, goes through a maximum with an increase in the solvent concentration. At a high solvent concentration, the solvent showed a toxic effect and it causes a decrease in the product yield by the second order inhibition mechanism. Among the solvents evaluated, methanol and ethanol were found to be the best. These alcohols are not only good solvents but also showed minimal toxic effect. Based on the experimental results, it was concluded that the productivity of steroid can be increased by usign well selcted solvents systems for the enzymatic transformation of steroids.

• 한국보건간호학회지
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• 제8권2호
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• pp.57-64
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• 1994

The purpose of this study is to investigate the present state of worker's physical. behavioral effects and recognition about the hazard factors in their workplace. The subject consisted of 208 workers in the organic solvents related industry. The workers were surveyed by means of a Questionnaire during the period of March 24 to May 26. 1994. The data were analyzed by descriptive statistics. t-test. AVOVA using the SAS program. The result of the study are follows: 1. The more than half of workers in the organic solvents related industry have experienced 'eye disturbance', 'headache', 'sputum formation' and 'dizziness'. 2. $83.4\%$ of workers have recognized the name of organic solvents in using of their workplace. $62.4\%$ of workers have recognized the harmfulness of organic solvents. $41.7\%$ of workers have not recognized the difference of harmfulness of various organic solvents. 3. $27.8\%$ of workers have called on clinic when have experienced physical symptoms. About $90\%$ of workers have called on hospitals and drugstores when have experienced physical symptoms.

• 생명과학회지
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• 제9권2호
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• pp.136-145
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• 1999

유기용제와 소음의 폭로가 청력손실에 미치는 영향을 알아보기 위해 유기용제 폭로군 32명, 소음 폭로군 31명, 소음과 유기용제에 동시에 폭로된 군 31명 그리고 대조군 53명을 대상으로 소음과 유기용제 폭로 정도와 청력손실치를 계산하여 얻어진 결과는 다음과 같다. 1. 조사 대상자들은 소음과 유기용제에 허용기준치 이하로 폭로되었으며, 요중 마뇨산 배설량도 참고치 이하로 배설되었다. 소음의 경우 소음과 유기용제 동시 폭로군과 소음 폭로군이 유기용제 폭로군보다 높았으며(p<0.05) 요중 마뇨산은 소음 유기용제 동시폭로군과 유기용제 폭로군이 소음폭로군보다 배설량이 더 많았다(p<0.05). 2. 주파수별 기도청력은 소음과 유기용제 동시 폭로군이 소음군보다 우측귀의 500Hz, 좌측귀의 500, 2000Hz에서 유의하게 더 높은 청력손실치를 나타내었고(p<0.05), 유기용제군과의 비교시에는 왼쪽귀 4000Hz에서 청력손실이 유의하게 더 높았다(p<0.05). 3. 조사 대상자 147명중 43명이 청력손실군에 해당되었으며 청력손실군의 연령이 42.6세로 정상군 38.0세 보다 더 높았으며 요중마뇨산 배설량도 유의하게 더 많았다(p<0.05). 4. 청력손실자는 소음군에서는 대상자의 38.7 $\%$(12명), 유기용제군 40.6 $\%$(13명), 소음과 유기용제 동시폭로군은 51.6 $\%$ (16명), 그리고 비폭로군은 3.8 $\%$(2명)의 빈도를 보였으며 비폭로군에 비해 폭로군에서 청력손실자가 많이 발생하였으나 폭로군 사이에서는 유의한 차이를 보이지 않았다. 5. 청력손실과 유의한 상관관계를 보이는 변수는 연령과 요중마뇨산 배설량이었으며, 유기용제로 인한 청력손실의 영향을 보기위해 연령을 보정하였을 때는 요중마뇨산 배설량만이 상관관계를 보였다(p<0.05). 6. 대조군과 폭로군사이의 청력손실에 대한 교차비에서는 비폭로군에 비해 소음폭로군은 6.1배(95 $\%$ CI,: 3.3-8.7),유기용제 폭로군은 7.4배(95 $\%$ CI,: 3.5-14.6) 그리고 동시폭로군은 1$\ulcorner$.2배(95 $\%$ Cl,: 5.31.8)로 더 켰다(p<0.01). 이상의 결과로 볼 때 유기용제 폭로 근로자에 대해서도 청력장애에 대한 건강진단이 실시되어야 할 것으로 생각된다.

• KSBB Journal
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• 제14권6호
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• pp.696-701
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• 1999

본 연구에서는 lipase를 이용해서 ricinoleic acid를 대량생산하기 위해 피마자유의 완전가수분해 조건을 찾고자 하였다. 널리 알려진 lipase CR, lipase CC, lipase PP를 대상으로 피마자유의 가수분해의 가능성을 시험하고, 유기용매를 사용함으로써 가수분해도를 향상시킬 수 있음을 확인하였다. 일반적으로 lipase의 활성을 감소시키는 극성용매의 경우 피마자유의 가수분해에 있어서도 효소의 활성을 감소시켰고, 물과 섞이지 않는 hydrophobic solvent가 피마자유의 가수분해도를 크게 증가시키는 것을 확인하였다. 본 연구에서는 isopropyl ether의 효과가 가장 크며, 조건에 따라 가수분해도를 두 배 이상 증가시킨다는 것을 확인하였다. 그리고 유기용매를 사용함으로써 pH의 영향을 바꾸거나 감소시킬 수 있다는 사실도 확인하였다. 용매와 물의 부피비에 의해서 가수분해가 영향을 받는다는 사실과 특히 유기용매보다는 물의 양에 절대적으로 영향받는다는 사실을 발견하였다. 하지만, 물과 유기용매의 부피비와 함께 lipase와 피마자유의 무게비도 매우 중요하다는 것을 확인하였다. 30$^{\circ}C$에서 isopropyl ether를 사용할 경우 무게 비로 2 wt%일 때는 약 82%, 4 wt% 이상의 lipase CC나 lipase CR을 사용하면 피마자유가 완전히 가수분해되는 사실을 발견하였다.

• Toxicological Research
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• 제11권2호
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• pp.205-213
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• 1995

This study was undertaken to investigate the effects of organic solvents on xenobiotic metabollzing enzyme system in vivo by meaas of experimental conditions i.e. (1) single group which was treated by benzene (B), toluene (T) and xylene (X), respectively, (2) combination group which was treated by mixture of benzene+toluene (BT), benzene+xylene (BX), and toluene+xylene (TX), respectively, (3) mixture group which was treated by benzene+ toluene+xylene mixture (M), and to interpreat the interaction between the organic solvents metabolizing enzymes. 1. The contents of cytochrome P-450 in liver microsomes were increased (p < 0.01) in organic solvents treated groups, and the contents of cytochrome P-450 were increased by following order of B < T < M < BT=BX < X < TX. 2. The activity of cytochrome P-450 dependent AHHase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the activity of AHHase was increased by following order of B < T < BT=BX=TX=xylene < M. 3. The activity of NADPH P-450 reductase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the order of M < combinated group < X < T

• 한국산업보건학회지
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• 제19권3호
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• pp.270-279
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• 2009

In order to check a necessity of health control for the laborers who are in use of mixed organic solvents in the printing industries, this study evaluated the use status of mixed organic solvents, health subjective symptoms on the exposure of the solvents, health hazard for each kind of printings for the employees who work for the printing industries located in Seoul and Gyeonggi. The study analyzed 228 sites and 311 people responded of the total 250 sites surveyed from March to September 2007, and obtained the following results; 1) Estimating the exposure of the mixed organic solvents, the study found that estimation of mixture(EM) was different for each kind of printings at a level of significance, excessiveness of EM was 7.5%, the highest, for gravure printing, 5.6% for screen printing, 4.7% for master printing, 2.9% for offset printing. 2) As to the mean scores of health subjective symptoms for each kind of printings, workers in screen printing showed high scores in every subjective symptom, of which symptom of central nervous system was 3.75, the highest, and the difference was statistically at a level of significance(p<0.01). 3) Results of the hazard analysis for carcinogens and non-carcinogens contained in the mixed organic solvents exposed to the workers showed that cancer risk of offset printing workers was $7.8{\times}10^{-9}$ for benzene, the mean cancer risk was $2.02.{\times}10^{-8}$ from Monte-Carlo simulation, and both risks did not exceed the US EPA permissible standard of $1{\times}10^{-6}$. The total hazard indices of the non-carcinogens estimated was 3.523, the highest, for gravure printing, 2.381 for master printing, 1.125 for screen printing, respectively, and all exceeded 1.

• 한국산업보건학회지
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• 제26권1호
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• pp.20-29
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• 2016

Objectives: The purpose of this study is to simplify and standardize analytical method of polar solvents(methanol, isopropanol, n-butanol, acetone, methylene chloride and MIBK) in the working environmental by GC. Because NIOSH methods are various and complicated. Methods: The method is using the same stationary phase(5% phenyl 95% dimethylpolysiloxane), absorbent(silica gel) and desorption solvent(DMSO) for above 6 solvents. For the 6 solvents desorption efficiency, calibration curve, and limit of detection were studied Results: As the results, 6 solvents{2 groups ; first group(methanol/isopropanol/butanol) and second group(acetone/methylene chloride/MIBK)} could be separated and quantified within 10 minutes. Desorption efficiency from silica gell of 6 solvents using dimethylsulfoxide(DMSO) was methanol 86.2%, isopropanol 103.2%, n-butanol 101.8%, acetone 98.2%, methylene chloride 103.9% and MIBK 106.2% in the range of 0.2, 0.5, 2.0 times of TWA, consequently, satisfied NIOSH estimation level(beyond 75%). Correlation coefficient(r)in the range of 0.2~2.0 times of TWA, was above 0.999 for 6 solvent. LOD(mg/DMSO ml) using calibration curve in the range of 0.2~2 times of TWA was methanol 0.11, isopropyl alcohol 0.20, n-butanol 0.03, acetone 0.50, methylene chloride 0.05, MIBK 0.04 respectably. Conclusions: This method can be used at the sampling and analytical method for polar solvents by GC. Also, will be able to be applied with NIOSH methods.

• Preventive Nutrition and Food Science
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• 제16권3호
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• pp.267-271
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• 2011

Static Headspace Gas Chromatographic analysis was used to study the partitioning behavior of five organic printing ink solvents between chocolate cookie/air systems. Three cookie sample formulations varied with respect to chocolate type and overall percentage of constituents. Major considerations involved differences in fat content and type and resulting variability in chemical and physical structure. Each of the solvents studied (ethyl acetate, hexane, isopropanol, methyl ethyl ketone, toluene) represents a general class of printing ink solvents based on predominate functional group. Values of the partitioning coefficient (Kp) were determined at equilibrium using measured quantities of both solvent and cookie sample in closed systems at temperature of 25, 35, and $45^{\circ}C$. In each of the three cookies at the three test temperatures, toluene always exhibited the greatest value of partitioning to cookie and hexane always exhibited the least. Results also showed that the partitioning behavior of solvents is generally inversely related to temperature and that solvent affinity, though constant for a particular cookie type over all test temperatures, varies significantly among the three cookie types. The preference of each of the five solvents for each cookie sample was also found to vary with temperature. No correlation was found between the extent of partitioning and cookie formulation or physical characteristic of solvent. The Hildebrand parameter, related to ${\Delta}Hmix$ (heat of mixing), may be used to describe differences in partitioning based on the overall potential of a solvent/cookie interaction to occur. The potential for interaction is dependent upon the chemical structure of the cookie sample and thus the availability of 'active-sites' required for a given solvent.