• Proceedings of the KWS Conference
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• 2004.05a
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• pp.21-23
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• 2004

파이프용접에서 특정용접을 하기 위한 최적의 용접조건 선정하는 작업은 대개 많은 시간과 비용을 요구한다. 최근에 인공지능(AI) 기술을 이용하여 용접변수를 결정하기 위해서는 생산성, 용접결함 등 여러 가지 요소를 고려해야 한다고 주장한다. (중략)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.985-993
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• 2001

Neural networks are shown to be effective in being able to distinguish incomplete penetration-like weld defects by directly analyzing the plasma which is generated on each impingement of the laser on the materials. The performance is similar to that of existing methods based on extracted feature parameters. In each case around 93% of the defects in a database derived from 100 artificially produced defects of known types can be placed into one of two classes: incomplete penetration and bubbling. The present method based on classification using plasma is faster, and the speed is sufficient to allow on-line classification during data collection.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.246-254
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• 2016

Thick-shell welding for super-sized oil storage tanks is currently done manually, which causes deterioration in quality and a lack of uniformity due to frequent rewelding. The limitations of the external environment must also be considered for manual welding. This paper describes the development of a carriage system for automatic vertical welding to increase reliability, reduce cost, and enhance productivity. The system consists of a welding platform, carriage device, and control unit, which were conceptually designed according to design specifications and manufactured with modular parts. In addition, the structure was analyzed for safety and to predict design problems in advance, and the results are reflected in reviewing the design. To evaluate the performance of the system, a tensile test, bending test, and weld time test were carried out, and the results were satisfactory. The time required for automatic weld was greatly improved by more than 87%, compared to the manual welding time.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.101-106
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• 2020

This research is related to a development of the ultrasonic detector for an internal defect detection of various assembly part's welding zone. In this research, measurement S/Ws including system's motion control, S/W ultrasonic transmitter/receiver control, defect judgment standard setting, etc. have been designed for ultrasonic detection, and welding defects sample network, etc. were also designed for comparison between products in good condition and defective products. Through this kind of system, automatic detection function can be performed for the depth and the defect location of the assembly parts welding zone, and the system is able to make a judgment of internal defect detection which is used to be performed by an expert in the past.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.2021-2026
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• 2013

In this study, the effect on the welding angle distortion was reviewed by carrying out a thermal elastic-plastic analysis while changing the cooling condition(width, length, and distance from weld torch to cooling torch) the back of the welding zone for the butt weld joint. The review results revealed that maximum 57% of reduction in the angle distortion was achieved when the distance between weld torch and cooling tip of 25mm, cooling length of 80mm, and cooling width of 30mm were maintained.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.16-16
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• 2009

Alloy 82/182로 용접된 원자력 발전소 주기기의 이종 금속 용접부는 장기간 운전 후 응력부식균열(SCC : Stress Corrosion Cracking)에 의한 결함이 나타나게 된다. 2000년대 이후로 원자력 주기기 Alloy 82/182 용접부에서 PWSCC(Primary Water Stress Corrosion Cracking)에 의한 Degradation이 급격히 증가하는 추세를 보이고 있으며, 국내에서도 이와 관련하여 원자력 발전소의 안전성에 대한 Issue 및 대비책에 대한 관심이 고조되고 있다. 이러한 Alloy 600 용접부에 대한 결함을 예방하기 위한 대표적인 기술로써 수명연장 오버레이 기술이 있다. 원자력 주기기 노즐부는 저탄소강으로 제작되어 있으며, 저탄소강에는 제작 시 용접후열처리가 적용된다. 후열처리를 하는 주된 이유는 Tempering을 통해 열영향부의 인성 및 연성의 회복과 강도를 감소시켜 모재와 동등 또는 이 이상의 물성을 갖도록 하는 데 그 목적이 있다. 그러나 수명연장 오버레이의 경우 현장 작업 시에 후열처리가 어렵기 때문에, 이를 대체하기 위한 기술로 템퍼비드 용접을 적용할 경우 후열처리를 면제해 주고 있다. 본 연구에서는 수명연장 오버레이 기술 개발의 일환으로써 저 탄소강에 대한 템퍼비드 용접 기술을 확립하였다. 실험에 사용된 모재는 원자력 주기기의 노즐에 사용되는 SA508 Gr.3 Cl.1을 사용하였으며, 용가재는 Alloy 52 및 52M을 사용하였다. 최적 조건 도출을 위해서 실험 매트릭스를 이용하여 기본 실험을 수행하였으며, 실험에는 자동 GTAW 용접을 적용하였다. 기본 실험을 통해 얻은 최적 조건을 사용하여 PQ 시험을 수행하여 WPS를 확보하였다. 분석은 용접 후 조직 및 경도 시험, 물리시험(인장시험, 굽힘시험 및 충격시험)을 수행하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.88-93
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• 2021

SAW (Submerged Arc Welding) is often used for ship construction or welding pressure vessels and involves spraying a flux in a powder form to a welding site to a certain thickness and continuously supplying electrode wires therein. This welding method enables high current welding up to 1,500 to 3,000 A. Arc efficiency is higher than 95% and the technique allows clean work as it creates less welding fume, which is composed of fine metal oxide particles, and the arc beam is not exposed. In this study, SM490C-TMC thick plates were heterogeneously welded by SAW. Mechanical properties of welds were measured, and welds were assessed macroscopically and for adhering magnetic particles. The following conclusions were drawn. Bending tests showed no spots exploded on sample surfaces or any other defect, and plastic deformation testing confirmed sufficient weld toughness. These results showed the 1F welding method has no shortcomings in terms of bending performance.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.367-372
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• 2010

A power plant's heat exchangers work under poor conditions, such as high temperature, high pressure, corrosion, mechanical stress and vibration. Especially, partial joint-weld of heat exchanger's header to stub-tube is the place where incomplete penetration flaws can easily occur. But, it is hard to evaluate the safety of the structure by conventional nondestructive testing techniques. So it is necessary to test integrity of the weld inside and to develop testing technique and equipment that can detect the flaws at the weld point in order to enhance reliability of the test result. In this study, we developed a suitable automated ultrasonic testing system that can inspect the partial joint-weld of header to stub-tube of power plant. Finally, we showed the efficiency of the automated ultrasonic-testing-system from the application.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.460-465
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• 2001

본고에서 피로균열성장에 대한 일반사항과 배관용접부 결함의 피로수명평가 방안에 대해서 알아보았다. 고압의 가연성 가스나 액체를 수송하는 배관이 피로에 의해 파괴되는 경우에는 엄청난 재산과 인적 손실을 발생시킬 수 있다. 따라서 배관운용회사들은 배관의 안정적인 운용을 위하여 다양한 환경에 노출되어있는 배관의 피로특성을 정확히 평가해야 한다.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.454-459
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• 2001

결함평가에 사용되는 작업자기준과 공학적 해석기준에 대한 비교와 각국에서 가스배관 원주용접부 결합평가에 사용하는 규격에 대한 검토를 수행하였다. 우리나라 가스배관 시공에는 API 1104를 기분으로 사용하고 있으며, 결함평가기준은 KSB 0845를 따르고 있다. 가스배관용접부에 대해 안전성과 효율성이 겸비된 새로운 결함평가방안을 구축하기위해 실배관 파열시험 및 대변형시험이 국내외에서 지속적으로 수행하고 있다.