• Archives of Reconstructive Microsurgery
• /
• 제13권1호
• /
• pp.68-73
• /
• 2004

Transverse rectus abdominis muscle (TRAM) free flap is widely used for breast reconstruction, however donor-site morbidities such as abdominal wall weakness, hernia, bulging are troublesome. For the purpose of minimizing donor-site morbidity, there has been a surge in interests in muscle sparing free TRAM flap preserving the anatomy of rectus abdominis muscle, fascia, and motor nerve. The purpose of this study is to investigate complication and morbidity after muscle sparing free TRAM flap. Between August, 1995 and May, 2003, there were 108 cases of muscle sparing free TRAM flap of breast reconstruction. There was no abdominal hernia. There were 4 cases of dog ear, 3 cases of marginal necrosis of apron flap, 2 cases of asymmetry of umbilicus. At 1 year after operation, most patients feel comfortness in physical exercise. Muscle sparing free TRAM flap provides ample amount of well vascularized soft tissue with small inclusion of rectus abdominis muscle and fascia. Also it minimizes donor-site morbidity with rapid recovery of abdominal strength.

• 한국소음진동공학회논문집
• /
• 제15권1호
• /
• pp.96-104
• /
• 2005

The coupled vibration characteristics for the fluid-structure interaction systems are investigated through the finite element method. The present paper is focused on vibration characteristics of the cylindrical fluid-storage tank with a baffle. The tank is partially filled with an inviscid and irrotational fluid having a free surface. A baffle is assumed here to have the shape of a thin annular plate and a conical shell, attached to the cylindrical tank and positioned below the fluid surface. The liquid domain is limited by a rigid flat bottom. As the effect of free surface waves is taken into account in the analysis, the bulging and sloshing modes are studied. To demonstrate the validity of present results, they are compared with the published ones. The effect of positions and inner-to-outer radius ratio of annular baffle and setting angles of conical baffle on coupled vibration characteristics is investigated.

• 대한기계학회논문집A
• /
• 제28권7호
• /
• pp.1006-1013
• /
• 2004

Operating experience of steam generators shows that the tubes are degraded by stress corrosion cracking, fretting wear and so on. These defected tubes could stay in service if it is proved that the tubes have sufficient structural margin to preclude the risk of tube bursting. This paper provides detailed plastic limit pressure solutions for through-wall cracks in the steam generator tubes. These are developed based on three dimensional(3D) finite element analyses assuming elastic-perfectly plastic material behavior. Both axial and circumferential through-wall cracks in free span and in u-bend regions are considered. The resulting limit pressure solutions are given in a polynomial form, and thus can be simply used in practical integrity assessment of the steam generator tubes.

• Archives of Reconstructive Microsurgery
• /
• 제11권2호
• /
• pp.141-145
• /
• 2002

Rectus abdominis muscle free flap is widely used for breast reconstruction and soft tissue defect in lower leg but donor-site morbidities such as abdominal wall weakness, hernia, bulging are troublesome. Recently, to minimize donor-site morbidity, there has been a surge in interest in deep inferior epigastric perforator(DIEP) free flap preserving the anatomy of rectus abdominis muscle, fascia, and motor nerve. Between August of 1995 and September of 2002, topographic investigation of DIEP was performed during the elevation of 97 cases of TRAM free flap and 5 cases of DIEP free flap. There were 84 cases of breast reconstructions, 12 cases of lower leg reconstructions, and 6 cases of head and neck reconstruction. We could observe total 10 to 12 perforators on each rectus abdominis muscle below umbilicus. Among these, the numbers of large perforators(>1.5mm of diameter) were mean 2.1 in lateral half of rectus abdominis muscle, mean 1.2 in medial half, and mean 0.5 in linea alba and paramedian. DIEP free flap provides ample amount of well vascularized soft tissue without inclusion of any rectus abdominis muscle and fascia and minimizes donor-site morbidity. One perforator with significant flow can perfuse the whole flap. For large flap, a perforator of the medial row provides better perfusion to zone-4 than one of lateral row and, if diameter of perforator is small, $2{\sim}3$ perforators can be used. According to the condition of recipient-site, thin flap can be harvested. As DIEP free flap has many advantage, perforator topography will be useful in increasing clinical usage of DIEP free flap.

• Archives of Plastic Surgery
• /
• 제37권5호
• /
• pp.571-576
• /
• 2010

Purpose: Reconstruction of soft tissue defects of the foot often requires free-flap transfer. Free muscle flap transfer and skin grafts on the muscle has been an option for these defects. Here we present our experiences of foot reconstruction using an endoscopy-assisted free muscle flap harvest. Methods: Using endoscopy-assisted free muscle flap harvests, four patients with soft tissue defects of the foot were treated with a free muscle flap and skin graft. The gracilis muscle was used for two patients and the rectus abdominis muscle for two. A single small transverse skin incision was placed on the lower abdomen for the rectus abdominis muscle. A small transverse skin incision on the proximal thigh was the only incision for harvesting the gracilis muscle flap. The small incisions were enough for the muscle flap to be pulled through. Results: The flaps survived successfully in all cases. Contours were good from both functional and aesthetic aspects. No breakdowns or ulcerations of the flap developed during long-term follow-up. Resultant scars were short and relatively hidden. Functional morbidities such as abdominal bulging were not noted. Conclusion: Endoscopy-assisted harvest of muscle flap and transfer with skin graft is a good option for soft tissue defects of the foot. Morbidities of the donor site can be minimized with endoscopic flap harvest. This method is preferable for young patients who want a small donor site scar.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 춘계학술대회 논문집
• /
• pp.253-257
• /
• 2005

A tube hydroformability testing system was designed and fabricated so as to observe the forming process and to apply forming condition along arbitrarily pre-programmed internal pressure-axial feed path. The forming limit diagram of A6063 extruded tube, of 40.6 mm outer diameter and 2.25 mm thickness, was successfully obtained through free bulging and T-forming tests except the region of high positive minor strain. It is found that the data points marked on the FLD are mostly located near the strain paths from the finite element analysis excluding the cases of large axial feed. There exist data points even in the area beyond the uniaxial tension mode, since the reduction in thickness decreases due to the axial feed. The forming limit from T-forming test was considerably lower than that from free bulge test. It seems because the deformation is localized at the pole.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2007년도 춘계학술대회 논문집
• /
• pp.314-317
• /
• 2007

Automotive rear subframe of aluminum tube was developed by using hydroforming process, based on the numerical analysis and physical tryouts. In the previous study, the effect of prebending was evaluated on the basis of forming limit diagram which had been obtained from free bulging, T-shape forming and cross-shape forming, using the developed tube hydroformability testing system. In order to get the sound products, appropriate internal pressure is to be imposed corresponding to the axial feeding. In this study, the loading path, the combination of internal pressure and axial feeding during the process, was optimized to ensure minimum thickness variation and dimensional accuracy, by using response surface method.

• 소성∙가공
• /
• 제8권1호
• /
• pp.92-100
• /
• 1999

A procedure is proposed for determining the initial thickness distribution in oder to produce a specified final thickness distribution for the axisymmetrical superplastic blow forming processes. Weighted parameter is introduced to improve the simple ad $d_traction method and the initial blank thickness distribution is obtained by optimizing the weighted parameter. This method is applied to superplastic free bulging process with the uniform thickness distribution of final shape to confirm its validity. The optimum initial blank thickness distributions is obtained from arbitrary axisymmetrical superplastic blow forming processes such as dome, cone and cylindrical cup forming with die contact. It is concluded that the ad $d_traction method with weighted parameter is an effective method for an optimum blank thickness distribution design.esign.

• 소성∙가공
• /
• 제21권3호
• /
• pp.151-159
• /
• 2012

Finite element simulations were conducted to investigate the influence of grain growth in the superplastic blow forming process. A microstructure-based constitutive model considering grain growth effects is proposed and used in the simulations. Also, a grain growth rate equation accounting for both static and dynamic grain growth is implemented. The simulations were made using a 2D plane-strain model for constrained blow forming and an axisymmetric model for free bulging. These two models showed different features during the forming stages. However, the forming pressure-time curve and the thickness distribution obtained by both simulations explained well the deformation hardening induced by the grain growth during superplastic forming. This study shows that grain growth is an important factor in determining the material behavior during superplastic deformation.

• 한국자동차공학회논문집
• /
• 제21권3호
• /
• pp.98-104
• /
• 2013

The effect of the tool-sheet interaction on formability enhancement in electromagnetic forming is investigated using FEM. A free bulging and a conical forming die with 0.7mm AL1050 sheet are used to evaluate damage evolution based on Gurson-Tvergaard-Needleman plasticity material model. The impact between the tool and sheet results in complex stress states including compressive hydrostatic stresses, which leads to a suppression of void growth and restrain ascending void volume fraction of the sheet. Therefore, the damage suppression due to the tool-sheet interaction can be the main factor contributing to the increased formability in the electromagnetic forming process.