• Safety and Health at Work
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• v.14 no.2
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• pp.215-221
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• 2023

Background: There is little information about the airborne hazardous agents released during the heat treatment when manufacturing a welding material. This study aimed to evaluate the airborne hazardous agents generated at welding material manufacturing sites through area sampling. Methods: concentration of airborne particles was measured using a scanning mobility particle sizer and optical particle sizer. Total suspended particles (TSP) and respirable dust samples were collected on polyvinyl chloride filters and weighed to measure the mass concentrations. Volatile organic compounds and heavy metals were analyzed using a gas chromatography mass spectrometer and inductively coupled plasma mass spectrometer, respectively. Results: The average mass concentration of TSP was 683.1±677.4 ㎍/m³, with respirable dust accounting for 38.6% of the TSP. The average concentration of the airborne particles less than 10 ㎛ in diameter was 11.2-22.8×10⁴ particles/cm³, and the average number of the particles with a diameter of 10-100 nm was approximately 78-86% of the total measured particles (<10 ㎛). In the case of volatile organic compounds, the heat treatment process concentration was significantly higher (p < 0.05) during combustion than during cooling. The airborne heavy metal concentrations differed depending on the materials used for heat treatment. The content of heavy metals in the airborne particles was approximately 32.6%. Conclusions: Nanoparticle exposure increased as the number of particles in the air around the heat treatment process increases, and the ratio of heavy metals in dust generated after the heat treatment process is high, which may adversely affect workers' health.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.126-136
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• 1996

Synthesis of perfluoromethanesulfonyl fluoride(PFMSF) which is a valuable precursor of perfluoro-chemicals such as surface modifier and fine chemicals was studied by electrochemical fluorination (ECF). In order to determine the termination of preelectrolysis, it was carried to monitor the variation of current during preelectrolysis by means of constant cell voltage operation. In a batch cell, chronopotentiometric electrolysis and various chemical analysis such as GC, GC/MS and If were used to understand the potential change of electrode and synthesis and control of hazardous gases products. Termination of preelectrolysis was determinated by measurement the current and/or detection of $F_2$ gas generation. And during the preelectrolysis, an amount of generated $OF_2$ was shown that a lot of moisture was absorbed from air when a cell was filled with anhydrous hydrogen fluoride( AHF ). Above 4V cell voltage, $F_2$ gas was generated and acted on any form of fluorinating agents. In the ECF of MSC (methane sulfonyl chloride) by constant current operation, the potential of anode was intimately relation with generation of $SO_2F_2$. Exchange of Cl to F was dominatly occured in a initial stage. There were various gaseous products including PFMSF as main product and $C_4$ compounds.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.81-88
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• 2018

This study analyzed the characteristics of 6 recyclable bulking agents which can replace sawdust and rice hulls that are commonly used in livestock manure composting. The content of all the hazardous chemicals found in the bulking agents used in this experiment was between 0.0 and 34.1 ppm, which was noticeably lesser than the maximum content levels of hazardous substances 5.0~900.0 ppm prescribed by the Rural Development Administration(RDA), which means that the bulking agents would be able to replace sawdusts and rice husks. The water content of the bulking agents ranged from a minimum of 12.4% to a maximum of 16.6% in the original state, which was much less than 60%, the optimal moisture content. These results indicate that they would be able to function fully as bulking agents. Their water absorption rate was in the range of minimum 31.9% ~ maximum 600.0%, which showed huge differences among the types of bulking agents. The most appropriate bulking agent in terms of water absorption rate was wood pellets. It was the highest in the wood briquette manufactured by A, which was followed by C and B in the order. The shear strength of the 5 types of bulking agents in the original state was 271.7 N on an average, the highest figure of all, except for the oak briquette whose shear strength could not be measured and the wood pellets in the absorption state. The shear strength in the dry and absorption states then followed, and were 78.0 N and 27.7 N on an average, respectively. The wood briquette of A recorded considerably lower shear strength than that of B and C. Overall, shear strength tended to increase according to lower water absorption rates. Since pine wood chips and oak cuts have relatively greater shear strength even in the absorbing state than the other materials, they will be able to endure some power in the case of stirring with pig droppings.

• Journal of Korean Public Health Nursing
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• v.11 no.2
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• pp.12-37
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• 1997

This study was performed to evaluate the subsidiary program on occupational health services in small scale industries. The survey of occupational health services was undertaken in 346 industries from July 1 to August 31. 1994. The major results were as follows ; 1. The subsidiary program on occupational health services The evaluation of working environments were conducted in 305 industries, $42.3\%$ of the industries had the harzardous agents exeeding TLV. Special medical examinations were done in 310 industries. the results were detected $C(33.3\%).\;D_1(0.8\%), D_2(5.4\%)$. Health management were done in 341 industries, the average visits for a industry were 3.8 times. The activities of health management were included to check of the workplace. health education, health counselling, etc. 2. The recognition of the employees and employers on occupational health services $91.5\%$ of employers and $87.0\%$ of workers felt healthy themselves. But $39.7\%$ of employers and $21.2\%$ of workers were under the stress from their jobs or home affairs. The workers perceived more harmful for the hazardous agents than the employers. $32.8\%$ of employers and $42.9\%$ of workers perceived that employer's efforts were the most important things to protect for the hazardous agents. The result of the evaluation of working environments were understood by $57.3\%$ of employers and $24.5\%$ of workers. The notification of medical examinations were recognized $83.9\%$ of employers and $50.3\%$ of workers. Many employers and workers felt the necessities of health management in small scale industries. The priorities of health manegement were different between employers and workers. Employers' priorities were as follows ; follow up care of medical examination$(97.3\%)$, health counselling$(93.7\%)$, planning of health$(93.5\%)$, health education of occupational diseases$(93.2\%)$, health education of chronic diseases$(93.5\%)$, etc. Workers' priorities were as follows ; follow up care$(93.4\%)$, health counselling$(94.3\%)$, health education of occupational diseases$(93.0\%)$. first aids$(92.0\%)$. etc.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.299-304
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• 2020

Nanoparticles play an important role as a catalyst in many chemical syntheses. Colloidal nanoparticles were usually synthesized with reducing, capping, and shape directing agents which induce surface poisoning of catalysts. A new green synthesis for silver nanoparticles was developed by utilizing less additives which could be a hazardous waste. A crystallization technique was employed to reduce the amount of reducing and capping agents during synthesis resulting in less surface poisoning of the nanoparticle. The synthesized Ag nanoparticles using monosaccharides and disaccharides as reducing agents could be used as a catalyst for the redox reaction of resazurin and the mechanism of the reaction using Ag nanoparticles was studied.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.478-483
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• 2014

Objectives: The main objective of this study is to assess the levels of hazardous substances in floor dust in primary schools located in the city of Busan in Korea. Materials and Methods: An on-site investigation of three primary schools was performed between April and May 2013. The hazardous substances measured in this study were 14 heavy metals (Cu, Fe, Pb, Mn, Ni, Zn, Cr, Cd, As, Al, Sn, Co, Mo and Si) and the biological agents were bacteria, fungi and endotoxin). Results: Among the heavy metals, Cd, Co, Pb and Cr were not detected in the floor dust from the three primary schools. The mean levels of other heavy metals were as follows: $20({\pm}10)ng/cm^2$ for As, $30({\pm}20)ng/cm^2$ for Al, $5({\pm}4)ng/cm^2$ for Sn, $20({\pm}20)ng/cm^2$ for Mo, $1,340({\pm}620)ng/cm^2$ for Si, $110({\pm}100)ng/cm^2$ for Cu, $240({\pm}50)ng/cm^2$ for Fe, $30({\pm}30)ng/cm^2$ for Mn, $10({\pm}10)ng/cm^2$ for Ni, and $50({\pm}30)ng/cm^2$ for Zn. It was found that mean concentrations of bacteria, fungi and endotoxin in the floor dust of primary schools were $4.7{\time}10^7({\pm}2.2{\time}10^7)cfu/cm^2$, $6.3{\time}10^6({\pm}6.4{\time}10^6)cfu/cm^2$, and $8,140({\pm}5,801)EU/cm^2$, respectively. The predominant species identified in the floor dust of the primary schools were Pseudomonas spp. for bacteria and Penicillium spp.,Cladosporidium spp.,and Aspergillus spp. for fungi, which would be somewhat similar to the microbial distribution pattern of other general environments. Conclusions: Based on the results obtained from this study, the levels of heavy metals, microbes and endotoxin distributed in the floor dust of primary school were higher than those reported for other general facilities. Thus, preventive measures should be prepared for the health care of children.

• Clean Technology
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• v.10 no.2
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• pp.73-87
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• 2004

In most of industrial fields, cleaning is employed for removing soils on their products or parts. Halogenated cleaning agents such as CFC-113, 1,1,1-TCE(1,1,1-trichloroethane), MC(methylene chloride) and TCE (trichloroethylene) have been used as cleaning ones in most of companies in the world since their excellent performance of cleaning ability and good material compatibility. However, CFC-113 and 1,1,1-TCE which are ozone destruction substances are not used any more in the advanced countries because of the which are ozone destruction substances are not used any more in the advanced countries because of the Montreal protocol. MC and TCE are now used restrictively at small part of industrial fields in most of countries since they are known to be hazardous or carcinogenic materials. Thus, it is indispensible that the alternative cleaning agents which are environmental-friendly and safe, and show good cleaning ability should be developed or utilized for replacement of the halogenated cleaning agents. Aqueous/semi-aqueous cleaning agents are evaluated to be promising alternative ones among various alternatives in environmental and economical view point. In this study, commercially available 12 aqueous and 6 semi-aqueous cleaning agents were selected and their physical properties, cleaning abilities, rinsing abilities and recycling of contaminated rinse water were measured and analyzed. Aqueous cleaning agents with higher wetting index showed better cleaning ability compared with those with lower wetting index. However wetting index did not have any correlation with cleaning ability in semi-aqueous cleaning agents. It was observed that soil concentration in aqueous and semi-aqueous cleaning agents should be maintained below the certain concentrations which depend on types of clearing agents. More than 70% soils in contaminated rinse water by some of aqueous and semi-aqueous clearing agents could be separated by simple settling method. This means that some cleaning agents with high oil-water separation efficiency will be effiective for recycling oil-contaminated rinse water. It was found that contaminated rinse water with aqueous agents was purified easiy by ultrafiltration method with PAN membrane of 30 kDa.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.1
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• pp.63-72
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• 2009

고령 근로자의 작업환경 실태와 건강검진 자료를 분석하여 그들의 건강한 생활과 삶의 질을 향상시킬 수 있는 정책의 기초자료를 마련하고자 시도되었다. 대상자는 부산, 경남지역에 소재하는 41개 사업장에서 유해인자에 노출되어 작업하는 공정에 있는 50세 이상 근로자 112명(남성 91명, 여성 21명)을 대상으로 소음, 분진, 유기용제, 중금속, 작업형태 및 작업강도 등을 측정, 분석하였으며, 건강검진 자료는 일반건강진단표를 이용하여 다음과 같은 결과를 얻었다. 1. 대상자의 평균연령은 54.9(남성 55세, 여성 54.7세) 세였으며, 평균근무기간은 8.7년이 였으며, 조사대상 사업장중 71.5%가 50인 이하의 근로자를 고용하고 있는 사업장이 였다. 2. 소음에 폭로 대상자 중 31.3%가 90dB(A)인 노출기준치을 초과하였으며, 그 외의 분진, 유기용제, 중금속 등의 노출기준치를 초과한 대상자는 없었다. 3. 조사대상자 중 9%는 청력이 비정상이였으며, 78.6%의 대상자는 경작업과 중등작업을 하였으며, 52.7%는 전신을 이용하여 작업하는 형태였다.

• Journal of Environmental Health Sciences
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• v.30 no.4
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• pp.320-328
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• 2004

A number of health hazards are generated in welding processes. In this paper, the characteristics of fumes and some other hazardous agents in welding are reviewed. Fumes in welding are generated by complex mechanism like physical ejection of particles, oxidation-enhanced vaporization, vaporization-condensation-oxidation, and spatter contribution. Fume generation rates could be described as a power function in a given process. Most of fume constituents was originated from consumables rather than base metal. The mass distribution for the welding fumes is unimodal and very small to penetrate respiratory system. So, almost fractions of fumes are classified into the respirable particulate mass. Total chromium contents in FCAW were similar to those from SMAW whereas hexavalent chromium concentrations in fume were similar to those produced from MIG welding fume. Hexavalent chromium was mostly soluble which was similar to the characteristic solubility of fume hexavalent chromium from SMAW.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.143-148
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• 2007

Recently indoor air pollution caused by exposing hazardous chemicals (VOCs, formaldehyde) due to undiscriminated use of new construction materials and air-tightness to save energy is becoming a big issue. We have developed technologies to estimate the amounts of contaminants from constructions materials and method. We have further developed construction technologies to reduce and characterize these contaminants. The developed technologies were then refined to eliminate defects through considering field applicability.