• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 심포지엄 논문집 정보 및 제어부문
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• pp.225-227
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• 2008

In this paper, universal wireless remote controllers are proposed. It can be used for general welding power sources. Sometimes, wireless remote controllers for welders are needed because welding torches are far away from welding sources in the case of big ship-building or big tank constructions. In order to use the wireless remote controllers, digital cpu-based welding systems are essential for digital interfaces. But, in this paper, using digital resistors makes wireless remote controllers be easily applied to digital or analog welders. To demonstrate the practical significance of our results, some experimental results are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.243-245
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• 2009

In this paper, wireless remote controller for welderss are implemented using RF communication. It can be used for general welding power sources. Sometimes, wireless remote controllers for welders are needed because welding torches are far away from welding sources in the case of big ship-building or big tank constructions. In order to use the wireless remote controllers, digital cpu-based welding systems are essential for digital interfaces. But, in this paper, using digital resistors makes wireless remote controllers be easily applied to digital or analog welders. To demonstrate the practical significance of our results, some experimental results are presented.

• 한국환경과학회지
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• 제14권1호
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• pp.9-14
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• 2005

This study evaluated the hazard caused by $NO_{2}$, an oxidant generated in the process of welding. We com­pared hematological and biochemical parameters in workers who chronically inhale $NO_{2}$ and office workers not exposed to $NO_{2}$. $NO_{2}$ exposure affected the hematological and biochemical parameters. Increasing $NO_{2}$ concen­trationincreased the number of leukocytes, while decreasing the number of erythrocytes. Blood urea nitrogen, cre­atinine, uric acid, and lactate dehydrogenase were increased, while total protein and triglycerides were decreased. The mean concentration of $NO_{x}(NO_{2}^{-}/NO_{3}^{-})$ in the serum of welders and the control group was $35.97{\pm}2.85\;and\;55.40{\pm}5.81\;{\mu}mol/L,$ respectively. The difference was significant (p < 0.05), although $NO_{2}^{-}$ was not detected in the serum.

• 전자공학회논문지S
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• 제35S권7호
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• pp.103-108
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• 1998

In this paper, we atempt to control the nonlinear power system for resistance spot welders to be a fully linearizesd system by applying the recently developed nonlinear feedback linearization techniques. the controller proposed in this paper is computationally simple. In addition, the easy gain tuning as well as the high dynamic performance of resistance spot welding systems can be obained simulaneously. To illustrate the dynamic performance of our controller further, we present some simulation results.

• Journal of Preventive Medicine and Public Health
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• 제31권3호
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• pp.449-459
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• 1998

This study was started to find out if plasma malondialdehyde(MDA), $\alpha-tocopherol$ and erythrocyte superoxide dismutase(SOD) activity could be markers of biological activity resulting from exposed to lead in workers. Blood samples were randomly obtained from lead-exposed workers(n=29), $CO_2$, welders(n=60) and office workers(n=60). We used whole blood to analyse blood lead with atomic absorption spectrophotometer. Superoxide dismutase activity in erythrocyte was measured with spetrophotometer. MDA and $\alpha-tocopherol$ in plasma were measured with high performance liquid chromatography. Lead-exposed workers was significantly high in blood lead concentration$(29.37{\mu}g/d\ell)$ compared with welders$(6.42{\mu}g/d\ell)$ and office workers$(5.01{\mu}g/d\ell)$. The level of plasma MDA was significantly higher in the lead-exposed workers($1.87{\mu}mol/g$ cholesterol) than the welders($1.41{\mu}mol/g$ cholesterol) and office workers($1.41{\mu}mol/g$ cholesterol). Erythrocyte SOD activity in lead-exposed workers(56.80 U/g Hb) was significantly increased than those of welders(37.63 U/g Hb) and office workers(20.47 U/g Hb). The plasma $\alpha-tocopherol$ level of lead-exposed workers($4.93{\mu}g/g$ cholesterol) was statistically different from welders($4.25{\mu}g/g$ cholesterol) and office workers$4.28{\mu}g/g$ cholesterol). Neither age nor smoking was related to SOD or MDA level. Blood lead was significantly correlated with erythrocyte SOD activity(r=0.405), plasma MDA(r=0.296) and $\alpha-tocopherol$ (r=0.207). Plasma MDA was also significantly correlated with SOD (r=0.217). In multiple regression analysis, the change of MDA and SOD activity level related to the blood lead concentration. These results suggested that the increase of plasma MDA and erythrocyte SOD activity in lead-exposed workers had a close relationship with the oxidative stress induced by lead.

• 한국산업보건학회지
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• 제26권2호
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• pp.147-158
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• 2016

Objectives: The objective of this study was to evaluate the assessment of exposure to welding fume and heavy metals among construction welders. Methods: Activity-specific personal air samplings(n=206) were carried out at construction sites of three apartment, two office buildings, and two plant buildings using PVC(poly vinyl chloride) filters with personal air samplers. The concentration of fumes and heavy metals were evaluated for five different types of construction welding jobs: general building pipefitter, chemical plant pipefitter, boiler maker, ironworker, metal finishing welder. Results: The concentration of welding fumes was highest among general building pipefitters($4.753mg/m^3$) followed by ironworkers($3.765mg/m^3$), boilermakers($1.384mg/m^3$), metal finishing welders($0.783mg/m^3$), chemical pipefitters($0.710mg/m^3$). Among the different types of welding methods, the concentration of welding fumes was highest with the $CO_2$ welding method($2.08mg/m^3$) followed by SMAW(shield metal arc welding, $1.54mg/m^3$) and TIG(tungsten inert gas, $0.70mg/m^3$). Among the different types of workplace, the concentration of welding fumes was highest in underground workplaces($1.97mg/m^3$) followed by outdoor($0.93mg/m^3$) and indoor(wall opening as $0.87mg/m^3$). Specifically comparing the workplaces of general building welders, the concentration of welding fumes was highest in underground workplaces($7.75mg/m^3$) followed by indoor(wall opening as $2.15mg/m^3$). Conclusions: It was found that construction welders experience a risk of expose to welding hazards at a level exceeding the exposure limits. In particular, for high-risk welding jobs such as general building pipefitters and ironworkers, underground welding work and $CO_2$ welding operations require special occupational health management regarding the use of air supply and exhaust equipment and special safety and health education and fume mask are necessary. In addition, there is a need to establish construction work monitoring systems, health planning and management practices.

• 한국안전학회지
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• 제13권2호
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• pp.65-75
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• 1998

The cases of welders illness by welding fume generated during arc welding are recently reported, which makes the legal regulation in the welding work place. Also, this situation makes the employers and welders be concerned about the welding fume seriously. At this point of time it is necessary that a standard testing method is developed as a fundamental tool for the evaluation of Fume Generation Rate(FGR) required for making progress in the development of low fume electrodes and welding process technology and also constructing the ventilation system in welding area. However, the current standard(KS D 0062) is only applicable to the manual covered electrode arc welding. In this study the evaluation procedure for the FGR is established by developing the fume collection chamber which can be applicable to semiautomatic and automatic arc welding as well as manual arc welding. This evaluation system and procedure can be used as a tool not only to develop the low fume welding electrode and welding process technology but also to construct the equipment controlling the welding workshop atmosphere.

• 한국산업보건학회지
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• 제1권2호
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• pp.154-163
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• 1991

Particulate matter exposure leva1 of welders and grinding workers was evaluated in Banwol and Changwon industry complexes. Full period single sample and full period consecutive samples were collected with personal air samplers attached to workers. Compliance difference with 8-hour time weighted average (TWA) was compared by Korean strategy and the classification system recommended by OHSA for employee exposure to particulates. And difference of compliance was compared according to precision of measurement and analysis (total precision). Compliance rate was depended on the total precision, therefore, quality control of measurement and analysis was important.

• 전력전자학회논문지
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• 제5권3호
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• pp.238-245
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• 2000

본 논문은 펄스 인버터용 TIG(Tungsten Inert Gas) 아크 용접기를 구현하는 용접전원장치의 성능에 관하여 알아본다. 용접전류는 펄스형태로 제어되고 또한 안정된 아크와 좋은 용접성능을 얻을 수 있다. DC 고전압 아크 스타트 시스템을 채용한 TIG 아크용접기에 대해 토치와 용접전원 사이의 연장 케이블이 50m 나 되어도 아크 스타트이 실패 없이 용접을 행할 수 있음을 알 수 있었다. 따라서, 이 DC 고전압 아크 스타트방식을 이용한다면 용접 전원장치와 용접장이 멀리 떨어져 있는 조선소와 같은 장소에서 요용하리라 생각된다. 이를 확인하기 위하여 시뮬레이션 및 실험을 행하였다.

• 한국산업보건학회지
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• 제10권1호
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• pp.45-57
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• 2000

Results of environmental monitoring for 35 steel industry welders exposed to manganese and chromium fume were evaluated. Efficiency of respiratory protectors, welding face shields and local exhaust ventilation were also evaluated to establish more efficient preventive measures that can protect welders from occupational disease as related to welding fume. The results are as follows; 1. Total fume from $CO_2$ arc welding with mild steel occurred 1.5 to 2.2 times more than that from shielded metal arc welding. Chromium and nickel fume from welding with stainless steel occurred 27 to 59 times and 18 to 30 times, respectively, than those with mild steel. 2. Proportions of water-soluble chromium(VI) and insoluble chromium(VI) Compare to total chromium occurring from $CO_2$ arc welding with stainless steel were 10.5% and 8.7%, respectively, while those with mild steel were 57.1 to 63.2% and 31.6 to 38.1%, respectively. 3. The efficiencies of 4 types of respiratory protectors to reduce welding fume exposure were evaluated as 54.4 to 64.4%. 4. The reducing effect of head type welding face shield was 67.6%, and that of hand type welding face shield was 58.5%. The highest reducing effect was shown in air supply welding face shield as 99.2%, although it is not convenient to wear. 5. When welding face shield and respiratory protectors were worn together, the reducing efficiency increased to 79.0 to 87.5%. 6. When local exhaust ventilation was installed in workplace, the reducing efficiencies varied from 31.5 to 73.1% according to the types of welding.