• 대한조선학회논문집
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• 제41권1호
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• pp.55-63
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• 2004

This paper is concerned with the simulator to estimate deformation due to welding of panel blocks. An efficient computer program system has been developed which can be applied to estimation of weld-induced deformation under the given welding conditions. The theoretical background of the present simulator is described with the prediction model for the various type of weld-induced deformation. The developed simulator has been applied to estimation of weld-induced deformation in panel block assembly. This paper ends with some findings from applying the developed simulator.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.266-272
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• 2002

This study reviews the factors controlling the weld metal cracking and shows the difference from those of HAZ cracking. It further reviews the recent progresses made in consumable design for improving the crack resistance in the high strength weld metal. Previously the controlling factors for weld metal cracking were regarded as weld metal strength, diffusible hydrogen and weld metal height. However an overall review presented in this article shows that the cold crack resistance can be improve significantly through the microstructural control and that an increase in tensile strength is not necessarily related to a decrease in the resistance to cold cracking.

• 한국생산제조학회지
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• 제9권3호
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• pp.160-168
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• 2000

Hydroforming is a metal forming process that enables circular metal tubes to be formed in to the parts with the complex cross section along the curved axial direction. Recently this hydroforming process is largely used for the production of the automotive parts. This paper presents the results of tube bending and hydroforming simulations in cases of the varying weld line positions of the tube. Ten cases of prebending and hydroforming simulations are carried out to find the optiaml weld line position.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.531-536
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• 1992

In GMA welding processes, monitoring and control of weld quality are extremely difficult problems. This paper describes a neural network-based method for monitoring and control of weld pool sizes. First, weld pool sizes are estimated via a neural estimator using multi-point surface temperatures, which are strongly related to the formation of weld pool, and then controlled using the estimated pool sizes. Two types of controllers using the pool size estimator are designed and tested. To evaluate the performance of the designed controllers, a series of simulation studies was performed.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 춘계 학술발표대회 개요집
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• pp.240-242
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• 2004

Effect of post treatment on the fatigue strength of a box weldment was investigated in order to improve fatigue life of the weldment. The post treatment applied were the smooth grinding of weld bead, weld toe grinding and hammer peening at the weld toe. The fatigue strength of the weldment after post treatment clearly increased, compared with that of the weldment in as-welded condition. After smooth grinding of weld bead, fatigue crack initiated at the root of the weldment, while fatigue crack initiated at the weld toe for the other methods.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.260-262
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• 2007

In nuclear power plants, residual stress of dissimilar metal weld propagates cracks in the weld metal which is susceptible to stress corrosion cracking. Overlay welding is a process widely used to mitigate residual stress replacing inside tensile stress by compressing stress. The purpose of this paper is to predict the effect of weld overlay by finite element analysis.

• 한국안전학회지
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• 제7권3호
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• pp.99-107
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• 1992

Weld bonding can be applied as a combined method of spot welding and adhesive to have more advantages than those. Weld bonding has many merits that enlarge the fatigue strength of spot Welding and also improve the creep of adhesive. But it has not beer proved well in the various environmental conditions. In this study, weld bonding test for fatigue properties and tensile strength is presented under such various coditions as temperatures, humidity, and etc.

• Nuclear Engineering and Technology
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• 제23권1호
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• pp.1-11
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• 1991

중수로형 핵연료봉단마개용접부의 품질검 사는 금속조직 검사에 따른 용접계면에 존재하는 불연속인 용접선(weld line) 길이가 가장 중요한 검사기준이다. 본 연구에서는 저항용접에서 가장 중요한 변수인 용접열의 변화에 따라 용접계면에서 용접선 소멸과 이 용접선이 용접부에 미치는 경향을 미세조직, 인장 및 파열시험으로 조사하였고, 또 주사전자현미경을 사용하며 파단면을 조사하였다. 용접열(main heat)의 변화에 따라 실제 용접에 사용된 전류와 업셋에 따른 시편길이 감소량은 증가하였으며 이들에 관한 상관관계식을 유도하였다. 용접열 50%근 용접된 용접부의 용접업셋 크기, 기계적 강도 및 용접선 소멸등을 고려한 결과 이것이 건전한 봉단마개 용접을 위한 임계치임을 알았다. 용접열을 50%에서 75%로 변화시킴에 따라 Zircaloy-4 용접부의 미세조직은 basketweave, Widmanstatten과 마르텐사이트로 변했고, 이는 용접시 최고도달 온도에 따라 냉각속도가 크게 변화했기 때문으로 사료된다. 인장시험에 의한 용접선 파단면에서 연성파괴의 dimple 형상은 2축응력에 의해 파열된 파단면의 dimple보다 크고 깊었음이 관찰되었다. 저항업셋용접부에서의 용접전류 증가에 따른 용접선의 소멸과정은 초기용접계면에 기공 존재, 이들의 수축과 소멸 및 초기계면 수축등 3단계로 구분할 수 있었다.

• Journal of Welding and Joining
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• 제32권4호
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• pp.63-68
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• 2014

This paper has an aim to study the effect of PWHT and its conditions(peak temperature and holding time) on the tensile properties and impact toughness of FCAW weld metal in relation to microstructure. Impact toughness was evaluated to apply the cargo tank of liquified gas carriers under the various PWHT condition of each class societies. On the basis of these study, it was found that PWHT conditions within all class societies affect charpy absorbed energy of weld metal little or no, all PWHT weld metals kept similar level of charpy absorbed energy as as-weld weld metal down-to $-60^{\circ}C$ and finally indicated lower energy value than that of as-weld weld metal at $-75^{\circ}C$. It is because the precipitation of 2nd phase was controlled from welding consumable and the grain size was grown by PWHT.

• 대한기계학회논문집A
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• 제29권10호
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• pp.1377-1383
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• 2005

A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly's dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.