• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.928-932
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• 1996

Single overload fatigue tests with overload sizes ranging from 50% and 100% have been performed to investing ate the fatigue crack growth retardation behavior. A modified and experimental method of Willenborg's model for prediction of crack growth retardation behavior has been developed, based on evaluations of equivalent plastic zone size (EPZS) changing its size along the overload plastic zone boundary. The minimum crack growth rates of each overload size are linearly decreased with overload size increasing, but fatigue lives extended by single overload are increasing much more unlike the crack growth rates. Comparisons of crack growth behavior predicted by EPZS model and Willenborg model have shown that the EPZS model accounts for overload effects better than Willenborg model. These effects include delayed retardation, large retardation region, minimum crack growth rate, and the increase rate of crack growth rate in the region crack growth rate recovered.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.385-392
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• 2003

Experimental investigation was conducted into the flexure/shear-critical behavior of earthquake-damaged reinforced concrete columns with lap splicing of longitudinal reinforcement in the plastic hinge region. Six test specimens in the aspect ratio of 2.5 were made with test parameters: confinement ratios, lap splices, and retrofitting FRP materials. They were damaged under series of artificial earthquakes that could be compatible in Korean peninsula. Directly after the pseudo-dynamic test, damaged columns were retested under inelastic reversal cyclic loading simultaneously under a constant axial load, P = 0.1 $f_{ck}$ $A_{g}$. Residual seismic performance of damaged columns was evaluated and compared to that of the corresponding original columns. Test results show that RC bridge piers with lap-spliced longitudinal steels in the plastic hinge region appeared to fail at low ductility. This was due to the debonding of the lap splice, which resulted from insufficient development of the longitudinal steels. The specimens externally wrapped with composite FRP straps in the potential plastic hinge region indicated significant improvement both in flexural strength and displacement ductility.y.

• Journal of Ship and Ocean Technology
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• v.8 no.3
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• pp.40-49
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• 2004

Welding deformations injure the beauty of appearance of a structure, decrease its buckling strength and prevent increase of productivity. Welding deformations of real structures are complicated and the accurate prediction of welding deformations has been a difficult problem. This study proposes a method to predict the welding deformations of large structures accurately and practically based on the simplified thermal elasto-plastic analysis method. The proposed method combines the inherent strain theory with the numerical or theoretical analysis method and the experimental results. The weld joint is assumed to be divided into 3 regions such as inherent strain region, material softening region and base metal region. Characteristic material properties are used in structural modeling and analysis for reasonable simplification. Calculated results by this method show good agreement with the experimental results. It was proven that this method gives an accurate and efficient solution for the problem of welding deformation calculation of large structures.

• Archives of Reconstructive Microsurgery
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• v.25 no.2
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• pp.37-42
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• 2016

Purpose: Soft tissue coverage of the distal leg and ankle region represents a surgical challenge. Beside various local and free flaps, the perforator flap has recently been replaced as a reconstructive choice because of its functional and aesthetic superiority. Although posterior tibial artery perforator flap (PTAPF) has been reported less often than peroneal artery perforator flap, it also provides a reliable surgical option in small to moderate sized defects especially around the medial malleolar region. Materials and Methods: Seven consecutive patients with soft tissue defect in the ankle and foot region were enrolled. After Doppler tracing along the posterior tibial artery, the PTAPF was elevated from the adjacent tissue. The average size of the flap was $28.08{\pm}9.31cm^2$ (range, 14.25 to $37.84cm^2$). The elevated flap was acutely rotated or advanced. Results: Six flaps survived completely but one flap showed partial necrosis because of overprediction of the perforasome. No donor site complications were observed during the follow-up period and all seven patients were satisfied with the final results. Conclusion: For a small to medium-sized defect in the lower leg, we conducted the close-by islanded PTAPF using a single proper adjacent perforator. Considering the weak point of the conventional propeller flap, this technique yields much better aesthetic results as a simple and reliable technique especially for defects of the medial malleolar region.

• Archives of Craniofacial Surgery
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• v.23 no.3
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• pp.103-110
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• 2022

Background: The primary objectives of mandibular surgery are to achieve optimal occlusion, low sensory disturbance, and adequate fixation with early movement. In-depth knowledge of the mandibular structure is required to achieve these goals. This study used computed tomography (CT) to evaluate the mandibular cortical thickness and cancellous space according to age and sex. Methods: We enrolled 230 consecutive patients, aged 20 to 50 years, who underwent CT scanning. The cortex and cancellous space centered around the inferior alveolar nerve (IAN) canal were measured at two specific locations: the lingula and second molar region. Statistical analysis of differences according to increasing age and sex was performed. Results: The t-test revealed that the cancellous space and cortical thickness differed significantly with respect to the threshold of 35 years of age. Both cortical thickness and cancellous space in the molar region were negatively correlated with age. Meanwhile, both cortical thickness and cancellous space in the lingula region showed a positive correlation with age. With respect to sex, significant differences in the cancellous space at the molar region and the cortical thickness at the lingula were observed. However, no further statistically significant differences were observed in other variables with respect to sex. The sum of each measurement on the mandibular body reflected the safe distance from the surface of the outer cortex to the IAN canal. The safe distances also showed statistically significant differences between those above and below 35 years of age. Conclusion: Knowledge of the anatomical structure of the mandible and of changes in bone structure is crucial to ensure optimal surgical outcomes and avoid damage to the IAN. CT examination is useful to identify changes in the bone structure, and these should be taken into account in the planning of surgery for older patients.

• Archives of Craniofacial Surgery
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• v.18 no.2
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• pp.122-127
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• 2017

Castleman's disease (CD) is an uncommon benign lymphoproliferative disorder of unknown etiology. Histopathologically, it is divided into three types: hyaline-vascular, plasma cellular, and multicentric CD. The mass usually presents asymptomatically; however, it can cause non-specific symptoms such as fever and fatigue. Although CD can be found wherever lymph nodes are present, 75% of cases are reported in the mediastinum, and occurrence in the head and neck is rare. Herein, we report a rare case of CD presenting as a superficial mass in the temporal region. To the best of our knowledge, this is the first report of temporal CD in Korea involving a young patient.

• Archives of Reconstructive Microsurgery
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• v.25 no.1
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• pp.15-18
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• 2016

Any types of burn injury that involve more than deep dermis often require reconstructive treatment. In gluteal region, V-Y fasciocutaneous advancement flap is frequently used to cover the defect. However, in case of large burn wounds, this kind of flap cannot provide adequate coverage because of the lack of normal surrounding tissues. We suggest V-Y adipofascial flap using the surrounding superficially damaged tissue. We present the case of a patient who was referred for full-thickness burn on gluteal region. We performed serial debridement and applied vacuum-assisted closure device to defective area as wound preparation for coverage. When healthy granulation tissue grew adequately, we covered the defect with surrounding V-Y adipofascial flap and the raw surface of the flap was then covered with split-thickness skin graft. We think the use of subcutaneous fat as an adipofascial flap to cover the deeper defect adjacent to the flap is an excellent alternative especially in huge defect with uneven depth varying from subcutaneous fat to bone exposure in terms of minimal donor site morbidity and reliability of the flap. Even if the flap was not intact, it was reuse of the adjacent tissue of the injured area, so it is relatively safe and applicable.

• Archives of Reconstructive Microsurgery
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• v.24 no.1
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• pp.16-19
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• 2015

The authors had five cases of penoplasty from more than half of the scrotum to the suprapubic region using a fasciocutaneous radial forearm free flap (RFFF) after extensive excision of sclerosing lipogranuloma. Although the harvested RFFF was a rectangular shape, the authors made the shape of scrotum, penile shaft, and suprapubic region by using well designed geometry and several quilting sutures on junction of scrotum and penis. The contour of scrotum and penis was well maintained, and there were no complications, such as scrotal contracture, penile deformity, and erectile dysfunction during the one year follow up period in all five cases. There were no recurrent lesions and no need for further surgery.

• Archives of Plastic Surgery
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• v.39 no.4
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• pp.281-283
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• 2012

The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.6 s.150
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• pp.683-692
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• 2006

The BEM, known as solving boundary value problems, could have some advantages In solving domain problems which are mostly solved by FEM and FDM. Lately, in the elastic-plastic nonlinear problems, BEM could provide the subdomain approach for the region where the plastic deformation could occur and the unknown nodal displacement of this region are added as the unknown of the boundary integral equation for this approach. In this paper, initial stress method was used to establish the formulation of such BEM approach. And a simple rectangular plate having a circular hole was analyzed to verify the suggested method and the result is compared with that from FEM. It is shown that the result of two methods are showing similar stress-strain curves at the root of perforated plate and furthermore the plastic deformation obtained by BEM shows more reasonable behavior than that of FEM.