• International Journal of Korean Welding Society
• /
• 제2권1호
• /
• pp.45-51
• /
• 2002

In the multi-pass welding of pressure vessels or ships, the mechanical touch sensor system is generally used together with a manipulator to measure the gap and depth of the narrow gap to perform seam tracking. Unfortunately, such mechanical touch sensors may commit measuring errors caused by the deterioration of the measuring device. An automation system of narrow gap multi-pass welding using a laser vision system which can track the seam line of narrow gap and which can control welding power has been developed. The joint profile of the narrow gap, with 250mm depth and 28mm width, can be captured by laser vision camera. The image is then processed for defining tracking positions of the torch during welding. Then, the real-time correction of lateral and vertical position of the torch can be done by the laser vision system. The adaptive control of welding conditions like welding currents and welding speeds, can also be performed by the laser vision system, which cannot be done by conventional mechanical touch systems. The developed automation system will be adopted to reduce the idle time of welders, which happens frequently in conventional long welding processes, and to improve the reliability of the weld quality as well.

• 국제초고층학회논문집
• /
• 제11권2호
• /
• pp.115-124
• /
• 2022

Welding is a significant part of the construction industry. Since most high-rise building construction structures rely on a robust metal frame welded together, welding defect can damage welded structures and is critical to safety and quality. Despite its importance and heavy usage in construction, the labor shortage of welders has been a continuous challenge to the construction industry. To deal with the labor shortage, the ultimate goal of this study is to design and develop an automated robotic welding system composed of a welding machine, unmanned ground vehicle (UGV), robotic arm, and visual sensors. This paper proposes and focuses on automated weaving using the robotic arm. For automated welding operation, a microcontroller is used to control the switch and is added to a welding torch by physically modifying the hardware. Varying weave patterns are mathematically programmed. The automated weaving is tested using a brush pen and a ballpoint pen to clearly see the patterns and detect any changes in vertical forces by the arm during weaving. The results show that the weave patterns have sufficiently high consistency and precision to be used in the actual welding. Lastly, actual welding was performed, and the results are presented.

• 한국생산제조학회지
• /
• 제21권2호
• /
• pp.349-353
• /
• 2012

As the world wind energy market grows rapidly, the productions of wind power generation equipment have recently increased, but manufacturers are not able meet this requirement. Particularly offshore wind energy industry is one of the most popular renewable energy sectors. To generalize welding processes, the welding automation is considered for steel structure manufacturing in offshore wind energy to get high quality and productivity. Welding technology in construction of the wind towers is depended on progress productivity. In addition, the life of wind tower structures should be considered by taking account of the natural weathering and the load it endures. The root passes are typically deposited using Gas Tungsten Arc Welding(GTAW) with a specialized backing gas shield. Not only the validation consists of welders experienced in determining the welding productivity of the baseline welding procedure, but also the standard testing required by the ASME section IX and API1104 codes, toughness testing was performed on the completed field welds. This paper presents the welding characteristics of the root-pass welding of high tensile steel in manufacturing of offshore wind tower. Based on the result from welding experiments, optimal welding conditions were selected after analyzing correlation between welding parameters(peak current, background current and wire feed rate) and back-bead geometry such as back-bead width(mm) and back-bead height performing root-pass welding experiment under various conditions. Furthermore, a response surface approach has been applied to provide an algorithm to predict an optimal welding quality.

• 한국산학기술학회논문지
• /
• 제13권4호
• /
• pp.1460-1465
• /
• 2012

본 연구에서는 소방배관용 아연도금 강관을 용접하기 위하여 반자동 가스메탈아크용접장치를 개발하고 최적 용접 조건을 확립하고 용접성을 조사하기 위해 보호가스, 전압을 변화시켜 용접시험을 수행하였다. Ar 가스에 $O_2$를 첨가함으로써 미려한 비드외관과 기공률이 감소되었다. 반자동 용접부는 기계적 강도와 용접이음효율이 수동용접부에 비해 약 1.8배 우수하였으며 수압시험에 의해 건전성이 확인되었다. 본 연구에서 개발된 반자동용접장치로 비숙련자도 강관용접이 가능하며 용접결함이 적고 용접생산성을 증대시킬 수 있을 것으로 기대된다.

• 대한임상독성학회지
• /
• 제4권2호
• /
• pp.175-179
• /
• 2006

Welders are exposed to a number of hazards including metal fumes, toxic gases, electricity, heat, noise, and radiation such as ultraviolet and infrared light. We encountered a patient who developed non-cardiogenic pulmonary edema within a day after cutting copper pipe with an oxyethylene torch. The patient was a 26-year-old welder. He complained of dyspnea, generalized myalgia, and febrile sensation the following morning. The patient's chest X-ray and chest CT scan showed extensively distributed and ill-defined centrilobular nodules. Both his symptoms and chest X-ray abnormalities improved spontaneously. We attributed the patient's symptoms to non-cardiogenic pulmonary edema due to nitrogen dioxide, reasoning that: 1) the pipe consisted only of copper, according to material safety data sheet (MSDS); 2) a previous report in the literature demonstrated increased nitrogen dioxide levels under similar conditions; 3) the patient's clinical course and radiologic findings were very reminiscent of non-cardiogenic pulmonary edema following accidental exposure to nitrogen dioxide.

• 한국전자통신학회논문지
• /
• 제6권6호
• /
• pp.897-902
• /
• 2011

본 연구는 용접기와 발전기를 통합하여 필요에 따라 발전기로 사용하다가 용접기로 사용할 수 있도록 시스템을 구성하는 것이다. 이와 같이 통합 시스템을 제안하기 위해서는 급속충전이 진행되지 않도록 전력 상태 정보를 관리하는 시스템 구성이 가장 중요하다. 가장 이상적인 충전은 임의로 전류를 조절하는 것이 가장 이상적이다. 충전은 가급적 적은 전류로 오래하면 좋지만 본 연구에서는 용접기와 발전기를 가장 이상적으로 융합하여 필요에 따라서 발전기 또는 용접기로 활용할 수 있는 시스템을 제안하고자 한다. 특히 사용자의 부주의로 인한 손상이 발생할 수 있게 되므로 회로 단락 보호, 과부하 보호, 역극성 보호, 자동 충전 조정 기능을 포함한 시스템에 관한 것이다.

• 한국산업보건학회지
• /
• 제19권3호
• /
• pp.182-194
• /
• 2009

This study was conducted to evaluate health status and to propose health protection measures of irregular plant construction workers in Yoesu National Industrial Complex (YNIC). The status of safety and health management was examined in five areas including safety and health education, work environment monitoring, health examination, health management record, and personal protective equipment (PPE) for plant construction workers. The safety training rate for plant construction workers was reached high at 91%, The training was mostly consisted of safety accident related things, but training on hazardous materials was found to be insufficient. Workplace monitoring results showed that the compliance rate for work environment for irregular construction workers was 54% and workplace monitoring during turnaround (TA) period with high risk of exposure to hazardous agents has not been implemented. While 61.4% of irregular workers received the general health examination but only 36.8% received the special health examination. The special health examination was found to be conducted only upon welders from 2-3 years ago. The issue of health management record upon irregular construction workers was not being implemented. In case of PPE, basic safety protective equipments such as safety shoes, safety belt, safety helmet were being supplied well while the supply rate of respirator for organic vapor was relatively low at 40%. Based on this study, two suggestions to maximize the utilization of the current safety and health program were made while boosting its effectiveness in protecting workers' health. First, the role of owners (petrochemical plant) related to safety and health should be strengthened. Second, in consideration of the characteristics of construction workers who usually engage in short term employment and frequent movement, community based health management organization is suggested that can overcome such structural problem and carry out the implementation of health examination and sustained health management.

• 산업공학
• /
• 제18권3호
• /
• pp.288-296
• /
• 2005

Many jobs and activities in our daily lives require squatting postures. The fore part includes housekeepers, farmers, and welders and the latter includes a wide variety of activities such as housekeeping; planting, cultivating and harvesting various agricultural products; grinding, welding, etc. It is speculated that prolonged squatting postures without any supporting stool would gradually cause musculoskeletal injuries to workers. This study is conducted to examine the proper height of stools according to the position of the working materials and to develop wearable stools for workers with squatting posture. Forty male and female subjects participated in the experiment to find the proper height of stools according to the position of the working materials. Subjects were asked to squat and work with 3 different working positions: floor level; ankle level; shank level of 3 different stool height conditions: 10cm height; 15cm height; and 20cm height. After 5 minutes of maintaining a squatting work posture while sitting on the different height stools, Likert summated rating method as well as pairwise ranking test was applied to evaluate the user preferences for provided stools under the conditions of different working positions. The results of statistical analysis show that the subjects preferred 10cm height stool for floor level, 15cm height stool for ankle level, 20cm height stool for knee level. We thus strongly recommend to use appropriate height stools in accordance with the different working positions. Moreover, a prototype wearable stool was designed such that workers with squatting posture do not need to move the stool while they are moving about. The purpose of developing wearable stool was to decrease the physical stress and hence promote worker's health who work with squatting posture.

• 한국산업보건학회지
• /
• 제9권2호
• /
• pp.135-144
• /
• 1999

The purposes of this study were to survey types of pretreatment methods adopted by industrial hygiene laboratories in Korea for extracting heavy metals in welding fume samples and to compare performances of two pretreatment methods, the acid extraction and the microwave digestion, in extracting heavy metals contained in the real workplace samples from various welding jobs including arc, argon, and carbon dioxide. A total of 25 analytical chemists in the industrial hygiene laboratories participating the quality control program directed by the Korea Industrial Safety Corporation were interviewed by telephone. For the purpose of comparing performance of extracting heavy metals from real workplace samples, a total of 53 welders from 21 workplaces located in Anyang, Uiwang, and Kunpo areas were sampled from the period of March 22, 1999 to April 20, 1999. It was found that the most frequently adopted method for samples from the quality control program was the acid extraction method(40%) followed by the NIOSH 7300 method(36%). The NIOSH method, however, was the dominant method(36%) for samples from workplace followed by the acid extraction method(28%). In this study, two extraction methods, the acid extraction and the microwave digestion, were compared in terms of recovery rate, accuracy, and precision for both manganese and chromium. Both methods produced comparable results for the samples prepared for the quality control program. In contrast, concentrations of two heavy metals determined from real workplace samples pretreated with the microwave digestion method were statis tically significantly higher, manganese(166%) and chromium (200%), than those of utilizing the acid extraction method. These findings were consistent regardless of types of welding techniques used. The results of this study clearly show the importance of verifying the analytical performances of extraction methods for heavy metals not only for the samples from the quality control program but also from the real world samples collected from welding jobs.

• 분석과학
• /
• 제27권5호
• /
• pp.248-253
• /
• 2014

이 연구는 Mn과 Pb의 노출이 면역체계에 미치는 영향을 파악하고자 하였다. 연구대상자는 남성 근로자 42 명으로, 대상자 중 13명은 사무직 근로자(실험군 I), 21 명은 제조업 사업장 근로자(실험군 II), 8명은 용접 작업자(실험군 III)였다. 대상자의 혈액 중 Mn과 Pb 농도는 실험군별로 유의한 차이를 보였다. 실험군 I 대상자의 CD19+와 total lymphocytes 농도는 기타의 실험군 대상자에서보다 유의하게 높았으나 다른 T lymphocytes subpopulation의 농도는 차이가 없었다. Mn과 Pb 농도는 T lymphocytes subpopulation과 음의 상관관계를 보였으나, Mn은 CD4+CD45RO+와 자연살해세포를 제외한 T lymphocytes subpopulation과 유의한 음의 상관관계를 보였다. Pb 농도는 단지 total lymphocytes 농도와 유의한 음의 상관관계를 보였다. 이 연구에서 Mn과 Pb의 직업적인 노출은 세포성면역계에 영향을 미칠 수 있음을 제시하였다.