• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.23-29
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• 2022

To detect harmful chemical substances in seawater, we fabricated a prototype sensor and evaluated its performance. The prototype sensor consisted of a detector, housing, and driving circuit. We built the detector by printing an Indium-Tin-Oxide (ITO) nanoparticle film on a flexible substrate, and it had two detection parts for simultaneous detection of temperature and HNS concentration. The housing connected the detector and the driving circuit and was made of Teflon material to prevent chemical reactions that may affect sensor performance. The driving circuit supplied electric power, and display measured data using a bridge circuit and an Arduino board. We evaluated the sensor performances such as response (ΔR), the limit of detection (LOD), response time, and errors to confirm the specification.

• Clean Technology
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• v.16 no.3
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• pp.172-181
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• 2010

Hydrofluoroethers (HFEs) with fluoride molecules in their structure which are evaluated as the third generation replacement alternatives to chlorofluorocarbons (CFCs) are known to be excellent for removal of nanoparticles and fluoride-type soils due to their low surface tension and high wetting index. In addition, HFEs have good physical properties with no flash point and excellent drying characteristics. But, HFEs also have shortcomings in that they are not effective for removal of organic soils due to their poor solubility in soil. In this study, $C_5$ HFE-based cleaning agents were formulated through addition of solvents such as isopropyl alcohol (IPA), ethyleneglycol monoether (EG), propyleneglycol monoethylether (PM) to HFE-7100 [$CF_3CF_2CF_2CF_2OCH_3$] or HFE-mec-f [$CF_3CHF=CF_2OCH_2CF_3$] with its maximum amount, respectively, in order to have no flash point for the safety in the working environment. These solvents are known to be excellent for dissolving organics in soil. Their physical properties and cleaning abilities for fluxes, water-insoluble cutting oils, and fluoride-type oils were evaluated and compared with those of other cleaning agents with single components. The experimental results show that the HFE-based formulated cleaning agents have various good physical properties which are almost similar to those of a single type of HFE cleaner. They show excellent cleaning ability for fluxes, water-insoluble cutting oils, and fluoride-type oils. These results indicate that the HFE-based formulated cleaning agents can be applicable to various industrial cleaning fields because of their good physical properties and cleaning abilities for various soils.

• Clean Technology
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• v.15 no.2
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• pp.81-90
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• 2009

In this study various cleaning evaluation methods were tested and comparatively evaluated to help cleaning industry. In order to select alternative cleaning agents objectively and systematically, various cleaning evaluation methods such as gravimetric, optically simulated electron emission (OSEE), contact angle, and analytical instrument methods were employed for cleaning contaminants such as flux, solder and grease. The analytical instruments used in this work were Fourier transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV-VIS) and high performance liquid chromatography (HPLC). The gravimetric method was able to measure cleaning efficiencies easily and simply, but it was not easy to analyze them precisely because of its limitation in the gravimetric measurement. However, the OSEE technique was able to measure quickly and precisely the clean ability of cleaning agents in comparison with the gravimetric method. The contact angle method was found to be necessary for taking special precaution in its application to the cleaning evaluation due to possible formation of tiny organic film on the substrate surface which might be generated from contaminants and cleaning agents. In case of precision analysis that cannot be done by gravimetric method, fine analytical instruments such as UV-VIS, FTIR and HPLC could be used in analyzing trace amount of flux, solder and grease quantitatively, which were extracted from the surface by special solvents.

• Journal of Environmental Health Sciences
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• v.49 no.6
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• pp.372-379
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• 2023

Background: Laundry workers are known to be exposed to organic solvents in various works including dry cleaning. Long-term exposure to organic solvents may cause adverse health effects among laundry workers. Objectives: To investigate the association between exposure to organic solvents and symptom of headache or eyestrain among laundry workers. Methods: The subjects were total 267 laundry workers who participated in the 6th Korean Working Conditions Survey (KWCS). Responses to exposure to 'inhalation of vapor from organic solvent' was categorized into two (non-exposed: rarely or absolutely not exposed during working hours; exposed: ≥1/4 working hours) or three (non-exposed; low exposure: 1/4 of the working hours; high exposure: ≥1/2 working hours) groups. Logistic regression analysis was performed to evaluate the association between exposure to organic solvents and symptom of headache or eyestrain in the last 12 months among laundry workers. Odds ratios (ORs) and the 95% confidence intervals (CIs) were calculated for experience of the symptom of headache or eyestrain with adjustment for age, sex, education, workplace size (by the number of workers), working hours per week, and current working period (year). Results: The proportions of exposure groups, i.e., non-exposed, low exposure, and high exposure, were 80.4%, 11.1%, and 8.5%, respectively. The proportion of those who had symptom of headache or eyestrain in the last 12 months was 18.7%. There was a significant association between exposure to organic solvents and experience of headache or eyestrain (OR=3.2, 95% CI=1.4~7.4). And, the proportion of those who experienced symptom of headache or eyestrain tended to increase significantly as the level of exposure to organic solvents increased (P_trend=0.002). Conclusions: Our results suggest that exposure to organic solvents are associated with symptom of headache or eystrain among laundry workers in Korea. However, further studies with more relevant design is needed to replicate the association.

• Clean Technology
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• v.25 no.4
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• pp.311-315
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• 2019

The cation extraction and impurity separation were studied in order to investigate the recyclability of a slag produced from the steel refinery industry. Two types of slag (Slag-A, B) were collected and characterized in this study. The initial characterization by X-ray diffraction (XRD) and X-ray fluorescence (XRF) confirmed the existence of various kinds of ions in the slag such as Ca²⁺ (30 ~ 40%), Fe³⁺ (20 ~ 30%), Si⁴⁺ (15%), Al³⁺ (10%), Mn²⁺ (7%), and Mg²⁺ (3 ~ 5%). Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis on the extracted slag using 2 M HCl as a solvent indicated that a higher concentration of Ca²⁺ was extracted as the S/L ratio was increased. The Ca²⁺ extraction concentration were found to be 8,940 mg L^-1 (Slag-A) and 10,690 (Slag-B) mg L^-1 when the S/L ratio for Ca²⁺ extraction was 0.1. However, the extract was strongly acidic ( < pH 1) at 0.1 S/L. Also the other ions (impurities) were extracted simultaneously in addition to Ca²⁺. To increase the purity of Ca²⁺ in order to transform the slag to a high value resource, a pH-swing was conducted. The impurities tended to precipitate at higher rate as the pH was increased. Notably, the Ca²⁺ rapidly precipitated above a certain pH and at a pH of 10.5, while the selectivity of Ca²⁺ was over 99%. It is expected that the aqueous solution in which high contents of Ca²⁺ was selectively dissolved in this study would be suitable for the carbonation process for reducing CO₂ and for the production of calcium carbonate.

• Journal of Food Hygiene and Safety
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• v.23 no.2
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• pp.98-107
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• 2008

The ozone has the oxidizing power which is powerful the fluorine and the antimicrobial spectrum of wide scope. Researches were carried out to use the merits that ozone has in various fields including the food industry, and many studies are also conducted nowadays for more efficient use of ozone. The ozone was permitted legally as a food additive and was practically used in the United States, Australia, Japanese etc. In November 2007, ozone water was permitted as a food additive in Korea and the interest in the use of ozone water has been on the rise in the Korea's food industry. As a olisinfectant method, ozone has many advantages. The maintenance and management expenses of ozone are lower than the installation cost at early stages and no by-products are generated after use it compared to others. Recently the demand of ozone as a olisinfectant method is increasing drastically. Although ozone water is popularly used to sterilize raw foods like fruits, vegetables and meats, the cases are still limited and were verified by the survey results. However, the use of ozone water is gradually being increased and is focused on food services. Ozone water refers to a state where ozone is dissolved into water to more conveniently use ozone. Accordingly, ozone water should be managed in regards with the amount and time of water-dissolved ozone, and the control of discharged ozone concentration is required for safe use of ozone water. The items to control mentioned above are directly related to the performance of the devices, and therefore, it is required to newly establish the performance criteria of ozone water manufacturing devices.

• Korean Journal of Head & Neck Oncology
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• v.9 no.1
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• pp.3-9
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• 1993

The benficial effects for perfusion in the preservation of free flaps have been controversial in the clinical and experimental field until now. This study was undertaken to observe the effect of UW solution. a recently developed. high molecular weight. organ perfusion solution. for protection of ischemic injury in normothermic free myocutaneous flaps. Forty rabbits were used in this sutdy. A 1x2x1cm sized gastrocnemius myocutaneous flap based on the feeding vessel from common femoral artery was made. The author set up the ischemic time for 12 hours in these flaps. The flap was washed out with normal saline(control grop, n=10), urokinase(comparative group I, n=10), UW solution before ischemic time(comparative group II, n=10) and UW solution before ischemic time and pentoxifylline before reperfusion(comparative group III, n=10). Afterthen, reperfusion was made for 12 hours. After this procedure, we checked the degree of ischemia and necrosis of myocutaneous flap by gross finding, electrical stimulation test of muscle, triphenyltetrazolium chloride staining and wet/dry weight ratio. The degree of necrosis of comparative group II and III were lesser than control and urokinase group in gross finding(p<0.05). In the electrical stimulation test of muscle, there was no statistical difference between control($1.76{\pm}1.01$) and urokinase($2.36{\pm}\1.02$) group however the muscular power of comparative group II($3.54{\pm}0.93$) and III($3.49{\pm}1.37gm/mm^2$) demonstrated significantly higher than control group(p<0.05). The ischemic findings were found in seven cases of control group and three cases of urokinase group but there were no ischemic findings in comparative group II and III in TIC stain(p<0.05). In the wet/dry weight ratio of flaps in order to evaluate the tissue edema. there was no statistical difference between control($4.55{\pm}0.29$) and III($3.75{\pm}0.48$) were scored significantly lesser than control and urokinase group (p<0.05). These results suggest that perfusion washout with UW solution improves the viability of normothermic free myocutaneous flap by inhibition of cellular swelling.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1407-1413
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• 2004

This study was performed to investigate the usage and management of flavorings inside or outside (Europe, Japan, JECFA and USA) for that establish a legislation about the flavoring management in Korea. Also, this study contributed to prevent confusion when manufacturers produce flavorings used in food industry. 6,434 among 8,386 flavorings authorized by Korea Food and Drug administration are compound flavorings, and 618 among 6,434 compound flavorings are synthetic flavorings. Many other substances except for flavorings are using as solvent in flavoring manufacture. Flavorings used in food industries of Korea are listed at least one among FEMA, JECFA, CoE and JFFMA except for isooctyl acetate and tricyclene. 493 items out of total 618 synthetic flavorings have completed safety evaluation by JECFA. 106 synthetic flavorings out of the rest listed FEMA as GRAS and 20 synthetic flavorings used in Japan. The replier answered that the most frequently used flavorings are strawberry, grape, orange, plum, lemon and vanilla flavor and that the usage of flavoring added to foodstuffs is less than 0.5%.

• Journal of Sericultural and Entomological Science
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• v.26 no.2
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• pp.11-15
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• 1984

To save the labour reguired for separation of copulated moth during egg Production, some of the chemicals available at the market were on screen test for easy separation of copulated moth of silkworm. The obtained results are summarized as following. 1. In a separation ratio of copulated moth along with a treating time, TCTFE(Trichloro-trifluoroethane) completely separated the copulated moth in 10 minutes. The combinations of TCTFE plus Acetone (87.5 : 12.5 V/V) and TCTFE plus Acetic acid (50 : 50 V/V) take 25minutes for the complete separation of copulated moth. Use of Acetic acid solution only makes 100% separation of copulated moth in one hour and foully minutes and non$.$treatment shows only 47.5% of separation in three and half hours. On the other hand. There is no statistical significance between TCTFE Plus Acetone and control in the egg productivity. 2. The combination of TCTFE Plus Acetone (87.5 : 12.5 V/V) does not infuluence the egg productivity of the moth, showing 443 grains for an average number of egg per moth out of which 417 grains are for the number of fertilized eggs while control shows 452 grains for an avarage number of egg/moth and 428 grains for the number of fertilized eggs. However a sing1e use of TCTFE and Acetic acid shows less egg productivity and number of ferilized eggs per moth, respectively as compared to those of the control. In particular, a single use of acetic acid makes an increase of number of non-egg prodncible moth and it seems to be brought due to a chemical damage. 3. In a rearing test of the egg laid by the chemical treated moth, there are no differences among the treatments in all of the useful characters of the larvae; larval duration, survival rate, cocoon yield, single cocoon weight, single cocoon shell weight and cocoon shell ratio. In these regards, it is recognized that TCTFE can be practically used for the separation of copulated moth and the combination of TCTFE and Acetone promote its efiectiveness on the separation of copulated moth.

• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.692-707
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• 1998

Aim. A neurobehavioral test for workers exposed to organic solvents in the workplace can be affected by many factors : age, education, motivation, ethnicity, etc. To apply more suitable neurobehavioral test for Korean workers, we evaluated the validity of several items of computerized and traditional neurobehavioral tests. Methods. We have applied eleven tests : four items of computerized neurobehavioral test(Swedish Performance Evaluation System) including Addition, Symbol-Digit, Dig-it Span, and Finger tapping speed, and seven items of traditional neurobehavioral test consisting of Addition, Digit-Symbol, Digit Span, Benton visual retention test, Pursuit aiming, Pegboard, and Tapping. These tests were performed on 96 workers exposed to solvents, and 100 reference workers. The concurrent and construct validities were evaluated by group difference, correlation with age, educational level, hippuric acid level, neurotoxic symptom, current exposure level, multitrait-multimethod matrix, fator analysis, and discriminant analysis. Results. Statistically significant differences were observed between the workers exposed to solvents and referents in computerized Symbol-Digit, Finger tapping speed, traditional Digit-Symbol and Pegboard. The computerized Symbol-Digit, traditional Digit-Symbol, Addition, Benton visual retention test, and Pegboard were found to be related to the age. The performance of computerized Symbol-Digit, Addition, and traditional Digit-Symbol were found to be related to the educational level significantly. The computerized Symbol-Digit, Finger tapping speed, and traditional Digit-Symbol were found to be related to hippuric acid, and neurotoxic symptom. The discriminability of Finger tapping speed, and Pegboard was better than the other tests. In discriminant analysis, the model with two variables, the computerized Symbol-Digit and Pegboard, classified almost 70 percent of the workers correctly. Conclusions. These results suggest that the computerized Symbol-Digit, Finger tapping speed, and Pegboard are more satisfactory for our purpose, and the Addition, Tapping, Benton visual retention test, and Pursuit aiming are less valid than other items. These may allow the reasonable selection of core neurobehavioral tests for workers exposed to solvents in Korea.