• Journal of Industrial Technology
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• v.24 no.B
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• pp.199-206
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• 2004

Recently social demands of fuel economy and environmental regulations require the development of lightweight components and new manufacturing technologies. The aluminum tube hydroforming is a manufacturing process which can provide lightweight components as automotive parts. In this paper, the hydroformability of aluminium tube in different condition of bending process is presented. An investigation has been conducted on how to control the deformed shape and its effect on thinning distribution after hydroforming by using finite element simulation. Finite element simulation of tube hydroforming for automotive trailing arm is carried out to explore the effect of 2-dimensional and 3-dimensional bending.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1630-1633
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• 2003

Hair pin bending machine is pipe forming machine consisting of heat exchanger product system. Hair pin produced by these machine is pathway of refrigerant and play a important role improving the performance and productivity of heat exchanger. The core technology of hair pin bending machine is forming the straight pipe into U-type without any defaults. Therefore, this paper study the relation between the pipe bending forming and the shape and position of mandrel using the elastic-plastic finite element analysis and provide a foundation technology for which developing the hair pin bending machine. The results are followed 1. Mandrel located in front of rotating center of bending die minimized the circular shape variation of copper pipe. 2. Diameter change of mandrel hardly effect the pipe shape.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.4
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• pp.24-31
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• 1988

The Upper Bound Solution has been used to investigate the effect of the various parameters on the floating-plug tube-drawing precess. A kinematically admissible velocity field considering the change of the tube thickness is proposed for the deformation process. Taking into account the position of the plug in the deforming region, shear energy at entrance and exit, friction energy on contact area, homogeneous energy are calculated. The theoretical values in proposed velocity field are good agreement with experimental values, It is investigated that the tube thickness in the deforming region is changed slightly toward minimization of deforming energy and then the drawing stress in lower than the crawing stress in the velocity field that the tube thickness is uniform.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.30.2-34
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• 1999

The hydroforming technology has gained in importance over the last few years, because of its potential for substantial weight avings costs reduction and quality improvement such as collision property, shape fixability and rigidity of white body. However, in comparison with the traditional sheet forming process, the hydroforming is much younger and the main development efforts were made in the last 15 years. The new technology, high pressure tublar hydroforming in particular, involves many process parameters to be optimized. This paper covers a brief overview of the hydroforming simulator as well as design of die and tools. The effects of typical parameters such as internal pressure and axial compression stroke are presented. Moreover, the conditions of forming failure occurrences such as fracture and wrinkle are examinated.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 2002.04a
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• pp.44-47
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• 2002

우리나라 시설재배면적은 2000년말 현재 52,189ha로 이중 가온재배 면적이 13,621ha에 다다르고 있으며 해마다 늘어나는 추세이다. 특히 연간 필요한 난방비는 약4천7백억원으로 상당한 에너지를 소비하고 있는 실정이다. 온실난방 에너지 절감을 위한 국내의 연구는 주로 보온, 난방기의 위치 및 Duct의 토출구 간격 및 직경(Kim 등, 1994), 난방배관 구조개선(Kwon 등, 1992) 지역별 난방부하 결정(Woo 등, 1998) 등을 중심으로 이루어져 왔으며 분화류와 같은 작물을 벤치재배하는데 벤치부분난방시 난방배관재의 종류 및 배관재의 간격등이 연구된바가 없으며 또한 최근 경기불황과 급격한 에너지 가격상승은 더욱 에너지 절감이 중요성을 부각시키고 있다. (중략)

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1810-1815
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• 2003

Tube hydroforming provides a number of advantages over conventional stamping process, including fewer secondary operation, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength and stiffness. In this study, the effect of the heat treatment on the hydro-formability has been investigated. By using the mild steel tube bulging test is performed at various heat treatment conditions to evaluate the hydro-formability.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.20 no.1
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• pp.29-38
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• 1991

설비분야(設備分野)에서 어느 용도(用途)에 어떤 재질(材質)의 배관재(配管材)를 사용하는 것이 가장 효과적(效果的)인가 하는 것은 관계 기술자(技術者)들의 관심사항중 하나이다. 특히 상수도(上水道) 분야(分野)는 정부(政府)가 주도하는 관계로 특별한 경우가 아니면 외국(外國)의 사례(事例)를 조사(調査)할 기회가 거의 없다. 본고(本稿)는 일본수도협회(日本水道協會)(JWWA)가 상수도(上水道) 기술정보(技術情報) 교환사업(交換事業)의 일환으로 미국의 주요 도시(都市)와 유럽의 주요 국가(國家)를 대상으로 실시한 상수도(上水道) 배관재(配管材) 사용실태(使用實態) 조사결과(調査結果)를 조사(調査)팀에 참가(參加)했던 관계기관(關係機關)을 통하여 입수(入手)하여 정리한 것이다. 조사(調査) 대상(對象)이 된 국가(國家)는 미국(美國), 스웨덴, 네델란드, 서독(西獨) 및 프랑스이며, 관계기관(關係機關)으로는 각국의 수도협회(水道協會)와 이와 유사한 9개 단체(團體)이다.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.127-133
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• 2007

SG-365 steel is an important material and used for manufacturing a pressure vessel which the gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the $J_{IC}$. It is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides, it improves the accuracy of toughness values, decreases a phenomenon of the tunneling and shear lip by the side groove.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.35-42
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• 2000

In this paper, we developed the hydroforming simulator which can apply an axial compressive force and high internal pressure to bulge a tube. Experimental dtudies have been performed to investigate the effect of each parameters such as internal pressure and axial compression stroke required for the forming of circular components. Under the improper forming conditions there were two forming failures. One was the axial buckling due to excessive axial compressive load and the other was the circumferential necking fracture due to relatively high internal pressure. A safe forming zone without any failures exists between these two extreme zones. Also the condition of forming failure such as fracture is examined throughout the theoretical analysis. This paper covers a brief overview of the mechanism of hydroforming process as well as the design of die and tools.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.244-247
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• 2009

Hydroformed parts have higher dimensional accuracy, structural strength, and dimensional repeatability. Particularly in the automotive industry, manufacturing of parts with complex shapes from tubular materials sometimes requires one or more pre-forming operations such as bending before the hydroforming process. The pre-bending process is an important factor for successful hydroforming in the case where the perimeter of the blank is nearly the same as that of final product. The bendability of a tube depends on the parameters such as the bending radius, variation of the diameter, thickness, hardness. This study shows the analysis of bending through the stainless steel tubes bent to rotary draw bending machine.