• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.225-232
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• 2004

Recently, there has been a rapid development in computer technology, which has in turn led to develop the automated welding system using Artificial Intelligence (AI). However, the automated welding system has not been achieved duo to difficulties of the control and sensor technologies. In this paper, the classification of the optimized bead geometry such as bead width, height penetration and bead area in the Gas Metal Arc (GMA) welding with fuzzy logic is presented. The fuzzy C-Means algorithm (FCM), which is best known an unsupervised fuzzy clustering algorithm is employed here to analysis the specimen of the bead geometry. Then the quality of the GMA welding can be classified by this fuzzy clustering technique and the choice for obtaining the optimal bead geometry can also be determined.

• 전자공학회논문지SC
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• 제45권4호
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• pp.60-67
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• 2008

본 연구에서는 일반적으로 용접기의 전원장치로 사용되어지는 풀-브리지 회로에 2개의 스위치와 2개의 무손실 스너버 부분 공진 커패시터, 2개의 다이오드로 구성된 간단한 액티브 보조 부분 공진 스너버를 추가한 새로운 하프 브리지 소프트 스위칭 PWM DC-DC 컨버터를 제안하였다. 제안한 하프 브리지 소프트 스위칭 DC-DC 컨버터 회로는 기존 회로의 DC 버스라인 스위치에 발생되는 도통 손실을 저감하여 고주파 변압기의 1차측의 전류가 2차측보다 작아지는 저 전압, 대전류 직류출력을 얻어 수 있었다. 그리고, 모든 영역에서 ZCS/ZVS 동작하므로써 저전압, 대전류 직류 출력의 스위칭 전원 장치에 있어 고주파, 고효율, 고출력을 실현할 수 있다. 이러한 모든 사항은 시뮬레이션과 실험 결과로부터 도출하였으며, 제안한 회로의 단점을 보완할 경우에는 차세대형 TIG MIG MAG 아크 용접기용 전원으로 용이할 것으로 판단된다.

• 한국공작기계학회논문집
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• 제16권2호
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• pp.92-99
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• 2007

Welding fabrication invariantly involves three district sequential steps: preparation, actual process execution and post-weld inspection. One of the major problems in automating these steps and developing autonomous welding systems, is the lack of proper sensing strategies. Conventionally, machine vision is used in robotic arc welding only for the correction of pre-taught welding paths in single pass. In this paper, novel presented, developed vision processing techniques are detailed, and their application in welding fabrication is covered. The software for joint tracking system is finally proposed.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.104-113
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• 2006

The main objective of this study is to investigate the effect of compounded welding by using acoustic emission (AE) signals and doing a source location for weld heat affected zone (HAZ) through tensile testing. This study was carried out an SWS 490A high strength steel for electric shield metal arc welding, SMAW; $CO_2$ gas metal arc welding, GMAW($CO_2$); and gas tungsten arc welding, GTAW/TIG. Data displays are based on the measured parameters of the AE signals, along with environmental variables such as time and load. For instance, Gutenberg-Richter magnitude-frequency relationship (G-R MFR) offers useful b-value in data analysis. Namely event identification, source location gives the X- and Y-coordinates of the AE source. And K-means clustering analysis by Euclidean distance confirmed that was powerful to source location. Generally, strength of welded metal zone was stronger than strength of base metal. As the result, confirmed certainly that fracture is produced in HAZ instead of welded metal zone from source location.

• 한국기계가공학회지
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• 제4권4호
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• pp.54-60
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• 2005

In a $CO_2$ inverter welding machine, stable arcs can be generated and a welding performance that is a goal of welding can be improved when stable electric power with a low voltage and a high current is supplied to a electrode that is the secondary part (output load terminal) and the base metal. For such a stable power supply, therefore, the AC arc welding machine, the thyristor welder, and the inverter welder have been developed in order according to development of the power electronics techniques. Up to now, the thyristor welding machine is still broadly used but the application volume is gradually reduced by development of the inverter welder. Because the welding performance of the inverter welder is very good and the weight and size of the welder is remarkably light and small. The final goal of this research is to develop the voltage loss compensator that is a drawback of the inverter welder and improve the welding performance using the developed compensator.

• Journal of Welding and Joining
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• 제30권5호
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• pp.46-50
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• 2012

This study was carried out to investigate the effect of welding parameters such as shielding gas compositions welding voltage and welding current on the pore formation in the weld beads of galvanized steel pipes produced with gas metal arc welding. The porosity was evaluated and rated by metallography and radiographic test in terms of weight percentage, number and distribution of pores in weld beads. The porosity increased with increasing welding voltage and current, in which Ar gas produced the most porosity while $Ar+5%O_2$ generated the least porosity. It was found that the porosity could be reduced by selection of the proper gas mixture composition such as $Ar+5%O_2$ and $Ar+10%CO_2$ and by using current (130~150A) and voltage(16~20V).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.529-534
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• 2000

Diode rectifier has been widely used as he preregulator of inverter arc welding machine(IAW). As it is linked to power utility a disorder of other instruments can be burst out. The adoption of voltage source PWM converters can be considered and which must catch the compromise of between performance and cost. So in this paper voltage source PWM converters which have single (i.e. PWM converter) control switch respectively are analyzed and evaluated through digital simulation and experiment. In addition the improved input characteristics of IAW are shown and compare to those of conventional one.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.260-264
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• 1998

Three phase Boost/Buck converter which have economical merits and simple control scheme, are analyzed and evaluated through comparative methods and digital simulation for equivalent load. Those play a part of voltage boost/buck as well as power factor correction with single switch. Controller operating in constant and variable frequency is used for rapid output response and stable system condition respectively. Moreover low THD property of single switched converters is available for inverter arc welding machine known as high power and low power factor. So, in this paper a comparison of the characteristics in boost and buck converter is described and then simulation results conforms the merits from point of view of power factor and voltage regulator.

• 한국공작기계학회논문집
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• 제16권4호
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• pp.87-92
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• 2007

The full automation welding has not yet been achieved partly because the mathematical model for the process parameters of a given welding task is not fully understood and quantified. Several mathematical models to control welding quality, productivity, microstructure and weld properties in arc welding processes have been studied. However, it is not an easy task to apply them to the various practical situations because the relationship between the process parameters and the bead geometry is non-linear and also they are usually dependent on the specific experimental results. Practically, it is difficult, but important to know how to establish a mathematical model that can predict the result of the actual welding process and how to select the optimum welding condition under a certain constraint. In this paper, an attempt has been made to develop an neural network model to predict the weld top-bead height as a function of key process parameters in the welding. and to compare the developed models using three different training algorithms in order to select an adequate neural network model for prediction of top-bead height.

• 대한조선학회논문집
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• 제53권6호
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• pp.473-481
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• 2016

Thick plate is currently widely used in shipbuilding due to the increasing of size of ships. However, its use has increased welding groove angles and volume. The welder's technique must be good enough to improve productivity while preventing defects. Generally, the groove angle can be reduced to less than a flux-cored arc welding (FCAW) machine setting of $35{\pm}5^{\circ}$, requiring fewer welding passes while maintaining high productivity and reduced heat input. Therefore, welding technique can be prevented by improved mechanical properties and welding deformation. Welding defects such as lack of fusion (LF), lack of penetration (LP) and hot cracking should be considered when reducing the groove angle for related applications. In this study, a welding groove angle of $25{\pm}5^{\circ}$ is verified as suitable for FCAW design and fabrication. The experimental results confirm the effects on the strength characteristics of FCAW weldment when reducing groove angle to improve the productivity of shipbuilding industries.