• Journal of Preventive Medicine and Public Health
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• 제32권2호
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• pp.141-146
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• 1999

Objectives: To ascertain whether some result of hematological examination could be as reference data for health management of welders. Method: The authors conducted the hematological examination of 1,018 welders and 531 control workers of a shipbuilding industry in Ulsan using automatic blood analyzer. Results: The WBC count of welders was lower than that of control on controlling the age and the duration of employment, but changes of other blood cells were not observed. Conclusion: We could use the results of hematological examination such as WBC counts as an indicator for subtle changes of health status of welders.

• Safety and Health at Work
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• 제8권3호
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• pp.258-266
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• 2017

Background: Welders are exposed to many known and suspected carcinogens. An excess lung cancer risk among welders is well established, but whether this is attributable to welding fumes is unclear. Excess risks of other cancers have been suggested, but not established. We investigated welding cancer risks in the population-based Canadian Census Health and Environmental Cohort. Methods: Among 1.1 million male workers, 12,845 welders were identified using Standard Occupational Classification codes and followed through retrospective linkage of 1991 Canadian Long Form Census and Canadian Cancer Registry (1992-2010) records. Hazard ratios (HRs) were calculated using Cox proportional hazards models based on estimated risks of lung cancer, mesothelioma, and nasal, brain, stomach, kidney, and bladder cancers, and ocular melanoma. Lung cancer histological subtypes and risks by industry group and for occasional welders were examined. Some analyses restricted comparisons to blue-collar workers to minimize effects of potential confounders. Results: Among welders, elevated risks were observed for lung cancer [HR: 1.16, 95% confidence interval (CI): 1.03-1.31], mesothelioma (HR: 1.78, 95% CI: 1.01-3.18), bladder cancer (HR: 1.40, 95% CI: 1.15-1.70), and kidney cancer (HR: 1.30, 95% CI: 1.01-1.67). When restricted to blue-collar workers, lung cancer and mesothelioma risks were attenuated, while bladder and kidney cancer risks increased. Conclusion: Excess risks of lung cancer and mesothelioma may be partly attributable to factors including smoking and asbestos. Welding-specific exposures may increase bladder and kidney cancer risks, and particular sources of exposure should be investigated. Studies that are able to disentangle welding effects from smoking and asbestos exposure are needed.

• 한국산업보건학회지
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• 제24권4호
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• pp.509-517
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• 2014

Objectives: This study was conducted to investigate the patterns of exposure of welders to strong magnetic fields for extended periods of time on the basis of their daily activities as recorded in a logbook. Methods: Male workers whose main job is welding, specifically seven welders occupied with gas tungsten arc welding(GTAW), two performing shielded metal arc welding(SMAW), and ten engaged in gas metal arc welding(GMAW), were measured in terms of the degree to which they were exposed to extremely low frequency(ELF) magnetic fields over 24 hours by using an electromagnetic field meter(EMF meter), as well as based on a daily activity log. Results: The welders were exposed to $1.25{\pm}4.95{\mu}T$ of magnetic field per day on average. For those who spent more than half a day-735.26 minutes, or 51.1% of the day-at work, the figure averages $3.88{\pm}8.85{\mu}T$ with a maximum value of $221.28{\mu}T$. The subject welders spent $338.14{\pm}154.95$ minutes per day at home. During their stays at home, they were exposed to an average of $0.17{\pm}0.06{\mu}T$ with a maximum value of $3.50{\mu}T$. The maximum exposure of $221.28{\mu}T$ occurred when welders performed GMAW. The average exposure reached its highest at $17.71{\pm}6.96{\mu}T$ when conducting SMAW. Magnetic field exposure also depends upon posture: welders who sat while welding were exposed five times more than those who stood during work, and this difference is statistically significant. As for the relationship between distance from the welding power supply and maximum magnetic field exposure, maximum magnetic field exposure decreases as the distance increases. The average magnetic field exposure, in the meantime, showed no significant difference depending on distance. Conclusions: The following were observed through this study: 1) welders, while conducting jobs, are exposed to magnetic fields not only from the welding machine, but also from the surrounding base material due to the current flowing between the welding machine and base material, meaning that they are continuously exposed to a magnetic field; and 2) welders are more exposed to magnetic fields while they sit at a job compared to when they stand up.

• Journal of Preventive Medicine and Public Health
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• 제22권3호
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• pp.328-336
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• 1989

27 shipyard welders were diagnosed as pneumoconiosis and suspected pneumoconiosis(1976-1988) by chest radiographs and were observed over three years. 27 welders were divided into three groups by the state of exposure to welding fume i.e. cessation, decresase or continuity of exposure. And we observed the changing pattern of the chest radiographs of 27 welders with the passage of time. The results were as follows; 1. Grour I (ceased exposure to welding fume) were 10 cases(3 cases: suspected pneumoconiosis,7 cases: pneumoconiosis). Chest radiographs of all cases were improved. The shape and size of small opacities was improved in 6 cases(85.7%) and did not changed in 1 case(14.3%) out of 7 pneumoconiosis welders. 2. Group II (decreased exposure to welding fume) were S cases(2 cases: suspected pneumoconiosis, 3 cases: pneumoconiosis). Chest radiographs were progressed in 2 cases(40%), did not changed in 1 case(20%), were improved in 2 cases(40%) out of 5 cases. The shape and size of small opacities was progressed in 1 case(33.3%) and was improved in 2 cases(66.7%) out of 3 pneumoconiosis welders. 3. Group III(continued expoxsure to welding fume) were 12 cases(1 case: suspected pneumoconiosis, 11 cases: pneumoconiosis). Chest radiographs were progressed in 9 cases(75%), did not changed in 3 cases(25%) out of 12 cases. The shape and size of small opacities was progressed in 1 case(9.1%) and did not changed in 10 cases(90.9%) out of 11 pneumoconiosis welders. 4. The average duration for development into suspected pneumoconiosis was 6.6 years and for progression of each one category after that was 2.2 years(p<0.01). The radiological appearance of pneumoconiosis had disappeared or decreased after cessation of exposure to the welding fume. So that, early detection and control e.g., change of department of pneumoconiosis of welders by screening program will be important for medical surveillance of welders.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.53-55
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• 1996

In this paper, we analyze control methods and structures of AC arc-welders, which is a prerequisite to develop a low-cost and high accurate welder. By using the finite element methods, three types of AC an-welders, movable-core, movable-coil, and saturated-reactor type, are modeled and characterized in the coupled domain of electro-magnetic system.

• 기술사
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• 제33권5호
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• pp.59-64
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• 2000

This improvement case to be introduced of all welders, welding operator, tack welders and welding inspector for reducing of welding defect rate and good quality.

• Journal of Preventive Medicine and Public Health
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• 제31권4호
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• pp.644-665
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• 1998

This study was conducted to evaluate the health hazards and to develop early diagnostic methods of the manganism in experienced welders and to know the meaning of signal intensities on the brain Magnetic Resonance images. It was carried out from December 1996 to february 1997 with 277 male welders, the duration of welding was at least 5 years or more. The study was consisted of a questionnaire, physical examination and measurements of blood & urine manganese concentrations. Brain Magnetic Resonance imaging was done on 19 study subjects by random sampling. As the duration of welding increases, the positive rates of clinical symptoms, neurological examinations and blood manganese concentrations were also increased. However, physical examinations and urine manganese concentrations were not statistically significant with the duration of welding. Authors couldn't observe any Parkinsonism-like diseases. There were statistically significant correlations between duration of welding and blood manganese concentration(r=0.16, p<0.01). There were not statistically significant correlations between duration of welding and urine manganese concentrations (r=0.06). There were statistically significant correlations between blood & urine manganese concentration(r=0.34, p<0.01). By viewing brain Magnetic Resonance images, 13 welders(68.4 %) among 19 welders were found to have signal intensities. The positive rates of clinical symptoms, physical examinations, neurological examinations and blood & urine manganese concentrations were not statistically different between those with signal intensities and those without signal intensities. We would like to suggest that some non-specific clinical symptoms and neurological signs are correlated with the duration of welding but any Parkinsonism-like diseases had not been observed with these welders. Next we suggest that the high signal intensities on TlWI of brain Magnetic Resonance images are not the sign of manganese intoxication but the sign of manganese deposition.

• Korean Journal of Radiology
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• 제1권2호
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• pp.79-83
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• 2000

Objective: To describe the thin-section CT findings of arc-welders' pneumoconiosis. Materials and Methods: Eighty-five arc-welders with a three to 30 (mean, 15)-year history of exposure underwent thin-section CT scanning. The extent of abnormalities detected was correlated with the severity of dyspnea and pulmonary function tests. For comparison, images of 43 smoking males (mean 25 pack-year) who underwent thin-section CT for other reasons (smokers' group) were also analyzed. Results: Fifty-four welders (63.5%) and six smokers (14.0%) showed positive findings. Predominant thin-section CT findings were poorly-defined centrilobular micronodules (30/54, 55.6%), branching linear structure (18/54, 33.3%), and ground-glass attenuation (6/54, 11.1%). In the smokers' group, poorly-defined micronodules were found in four patients, branching linear structures in one, and ground-glass attenuation in one. In welders, the extent of abnormalities seen on thin-section CT showed no significant correlation with the severity of dyspnea or the results of pulmonary funotion test. Conclusion: Poorly-defined centrilobular micronodules and branching linear structures were the thin-section CT findings most frequently seen in patients with arc-welders' pneumoconiosis. Less commonly, extensive ground-glass attenuation was also seen.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.556-559
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• 2000

Pulse inverter-type TIG(Tungsten Inert Gas) arc welders are studied to investigate the dynamic performance of welding. Welding currents are controlled to be pulse waveforms resulting in stable are better welding performance. The hybrid-type controller is proposed to control the welding current. Todemonstrate the practical significance of our results we present some simulation results.

• Tuberculosis and Respiratory Diseases
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• 제42권5호
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• pp.713-722
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• 1995

연구 배경: 탄광부 전폐증과 조선소 용접공 폐증의 흉부 X-선 소견은 유사한 규칙성 음영을 보이는 예가 대부분이지만 이를 흉부 X-선만으로 구별한다는 것은 극히 어려운 일이다. 본 연구는 탄광부 진폐증과 용접공 폐증의 흉부 X-선 소견에 따른 폐기능과 다른 요인들을 비교하여 두 질환의 진행과정과 그것에 대한 대책에 도움을 주고져 한다. 방법: 탄광부 진폐증 430명과 용접공 폐증 311명을 대상으로 흉부 X-선 소견에서 소원형 음영의 조밀도에 따라 진폐의증, 1형, 2형으로 나누어 분포, 나이, 분진의 노출기간, %폐활량, 1초율 및 환기장해의 행태, 동반된 폐질환 등을 서로 비교하였다. 1) 탄광부 진폐증에서는 2형이 54.1%로 가장 많았고 용접공 폐증에서는 1형이 55.95%, 2형이 7.4%로 탄광부 진폐증에서 2형으로 진행도가 높았다. 2) 평균연령은 용접공 폐증에 비해 탄광부 폐증에서 유의하게 높았고, 소원형 음영의 조밀도가 증가함에 띠라 탄광부 폐증과 용접공 폐증에서 유의한 증가를 보였다. 3) 분진 노출의 기간은 진폐의증에서는 유의한 차이가 없었으나, 1형과 2형의 탄광부 폐증에서 유의한 증가를 보였고, 소원형 음영의 조밀도가 증가됨에 따라 탄광부 폐증에서는 2형이 진폐의증과 1형보다 유의하게 증가하였으나, 용접공 폐증에서는 유의한 차이가 없었다. 4) %폐활량은 1형을 제외하고는 탄광부 폐증과 용접공 폐증에서 유의한 차이가 없었고, 소원형 음영의 조밀도에 따라서도 두 그룹에서 일정한 경향이 없었다. 5) 1초율은 진폐의증을 제외하고는 1형과 2형에서 탄광부 폐증에서 유의하게 감소하였고, 소원형 음영의 증가에 따라 탄광부 폐증에서는 유의한 감소를 보였으나 용접공 폐증에서는 진폐의증에 비해 2형에서만 유의하게 감소하였다. 6) 두 그룹에서 흡연과 비흡연에 따른 %VC, $%FEV_{1.0}$의 유의한 차이를 보이지 않았다. 7) 폐기능 장해의 유형에 따라 탄광부 폐증에서 구속형 상해가 21.4%, 폐색형 장해가 11.6%, 혼합형 상해가 5.6%이고, 용접공 폐증에서 구속형 장해가 21.8%, 폐색형 장해가 2.9%, 혼합형 장해가 1.9%를 보였고, 탄광부 폐증에서는 조밀도가 증가할 수 록 폐색형 장해는 증가하였다. 8) 두 그룹에서 폐결핵의 발병률이 가장 높았으며 용접공 폐증에서보다 탄광부 진폐증에서 높았다. 결론: 탄광부 진폐증과 용접공 폐증에서 흉부 X-선 소견과에 따른 폐기능 비롯한 다른 요인들을 비교하면 질병의 진행정도와 진행에 대한 대책에 도움을 줄 것으로 생각된다.