• Journal of Welding and Joining
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• 제6권2호
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• pp.19-29
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• 1988

This paper reports on the elatic-plastic analysis and fracture behavior of cylinder with outer surface crack which is under external or internal pressure. For the studuty of crack length effects in cylinder, ratios of crack lengths to finite thickness (a/t) are dertermined 0.3, 0.4, 0.5. For the study of curvature effects in cylinders, ratios of mean diameter to finite thicknees (Rm/t) are determined 10.0, 15.0, 20.0. Analysis is conduceted using the theory of fracture mechanics and two dimensional finite element solution assuming the axi-symmetrical plane strain conditon. Main results of this study are as follows. 1) It is known from this paper that elastic-plastic strain is initiated near crack tip and enlarged between crack tip and inner side of cylinder. 2) $K_{1}$ of cylinder under external or internal pressure is evaluated memebrane stress .root..pi.* crack length. The results of this study are inclined to Lomacky's results and Kobayshi's result. 3) Distribution of stress near crack tip is looked higher than of other zone, as crack length of equal model is longer, and as diameter of cylinder is longer. 4) When other conditions are equal, displacemenet near crack tip is looked duller, as length is longer.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.290-297
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• 1998

In this paper, we propose to a method to estimate the elasto-plastic buckling for single layer latticed domes. First, we assume that each member consists of the rigid zone and elastic spring at both end joint, the elastic element and three elasto-plastic spring to judge for yeilding the member. Next, the member which has most influence on buckling for structures is determined by a distributed pattern of the strain energy which is calculated through linear eigenvalue analysis. And then, normalized slenderness ratio of the element is derived considering the axial force at elastic buckling load. Later, we execute elasto-plastic nonlinear analysis that based on loading increasement method and displacement increasement method. From this results, we discusses the effect of the joint rigidity and the half open angle $\theta$$_{0}$ on the buckling strength of single layer lattice domes ; (1) how the joint rigidity contributes to the reduction of buckling loads, (2) how the reduction can be interrelated to compressive strength curves in terms of the generalized slenderness for the member most relevant to the overall buckling of domes.s.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1813-1821
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• 2004

Until now, the 40% of wall thickness criterion, which is generally used for the plugging of steam generator tubes, has been applied only to a single cracked geometry. In the previous study by the authors, a total number of 9 local failure prediction models were introduced to estimate the coalescence load of two collinear through-wall cracks and, then, the reaction force model and plastic zone contact model were selected as the optimum ones. The objective of this study is to estimate the coalescence load of two collinear through-wall cracks in steam generator tube by using the optimum local failure prediction models. In order to investigate the applicability of the optimum local failure prediction models, a series of plastic collapse tests and corresponding finite element analyses for two collinear through-wall cracks in steam generator tube were carried out. Thereby, the applicability of the optimum local failure prediction models was verified and, finally, a coalescence evaluation diagram which can be used to determine whether the adjacent cracks detected by NDE coalesce or not has been developed.

• Archives of Plastic Surgery
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• 제49권4호
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• pp.482-487
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• 2022

In lower abdominal flap representing transverse rectus abdominis musculocutaneous (TRAM) flap or deep inferior epigastric perforator (DIEP) flap, superficial inferior epigastric vein (SIEV) exists as superficial and independent venous system from deep system. The superficial venous drainage is dominant despite a dominant deep arterial supply in anterior abdominal wall. As TRAM or DIEP flaps began to be widely used for breast reconstruction, venous congestion issue has been arisen. Many clinical series in regard to venous congestion despite patent microvascular anastomosis site were reported. Venous congestion could be divided in two conditions by the area of venous congestion and each condition is from different anatomical causes. First, if venous congestion was shown in whole flap, it is due to the connection between SIEV and vena comitantes of DIEP. Second, if venous congestion is limited in above midline (Hartrampf zone II), it is due to problem in venous midline crossover. In this article, the authors reviewed the role of SIEV in lower abdominal flap based on the various anatomic and clinical studies. The contents are mainly categorized into four main issues; basic anatomy of SIEV, the two cause of venous congestion, connection between SIEV and vena comitantes of DIEP, and midline crossover of SIEV.

• Archives of Plastic Surgery
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• 제35권3호
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• pp.321-324
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• 2008

Purpose: Lymphoma originated from mucosa associated lymphoid tissue(MALT) is most common in gastrointestinal system, and rarely found in salivary gland, thyroid, bronchus or orbit. We experienced a case of MALT lymphoma which was originated from conjunctiva and involving lower eyelid without metastasis. Methods: A 40-year-old man suffered palpable mass on right lower eyelid without pain. Orbital computed tomographic and ultrasonographic findings showed a conical mass($1.9{\times}1.2{\times}0.9cm$ size) inside lower eyelid. The mass was completely excised under local anesthesia and histopathological examination was followed. Results: Microscopic finding showed a multiple follicular colonization. In the follicle, small lymphocytes and plasma cells differentiated to centrocyte-like cell, monocyte B cell, plasma cell were diffusely infiltrated. Immunophenotyping was preformed on fixed section. The majority of the small cells were immunoreactive for the B cell marker CD20. Based on the typical histological findings supported by immunostaining, the mass was defined as MALT lymphoma. After excision, SPECT, abdominal CT was carried out and there were no evidence of extraorbital disease. Conclusion: Biopsy and pathological examination should be performed in patients who complain palpable mass on lower eyelid because of possibility of MALT lymphoma. Although MALT lymphoma is rarely metastasized, it is necessary to evaluate the extraorbital involvement using SPECT or other radiologic exams. For detecting extraorbital involvement, periodic follow-up examination is need.

• Archives of Plastic Surgery
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• 제32권2호
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• pp.231-236
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• 2005

Nowadays breast reconstruction with autologous tissues after radical mastectomy is commonly performed, and a natural inframammary fold in the reconstructed breast is considered to be an essential aspect of symmetrical breast shape and location. Total of 104 patients underwent breast reconstruction with free TRAM flap and formation of inframammary fold with free TRAM breast reconstruction was done in 79 patients. No suture fixation for inframammary fold were done in 19 patients. 27 patients(24.0%) were made of inframammary fold with absorbable suture, 52 patients (50.0%) underwent inframammary fold creation with nonabsorbable suture. There were 4 cases(16.0%) of displacement of reconstructed breast and 2 cases(8.0%) of partial disruption of inframammary fold in the group of no suture. There were 2 cases(7.4%) of displacement of reconstructed breast and 3 cases(11.1%) of partial disruption of inframmamary fold in the fixed group with absorbable suture. There was only 1 case(1.9%) of partial disruption of inframammary fold fixed with nonabsorbable suture group. Therefore, we could speculate that the reinforcement of ligamentous structure for making the definite inframammary fold is necessary, and the area of the inframammary fold should not be undermined in immediate breast reconstruction as much as possible in order to preserve the zone of adherence. If the fold is disrupted during the mastectomy, it should be re-created with the non-absorbable sutures. Nonabsorbable suture fixation seemed to be more stable than absorbable suture. Preoperative marking and design are very important to make the symmetrical shape and location of inframammary fold in both of immediate and delayed reconstruction of breasts.

• Archives of Plastic Surgery
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• 제34권3호
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• pp.342-345
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• 2007

Purpose: A common side effect of the scalp reduction is a creation of a 'slot' with the hair growing in the opposite directions away from the scar. Overcoming the unnatural appearance of the slot has been a vexing problem in the scalp reduction surgery. None of the conventional corrective surgical techniques provides a complete and satisfactory aesthetic result. The Frechet flap is a triple transposition flap used for the correction of the slot defect secondary to scalp reduction surgery, seldom needing further scar revision. The Frechet technique provides a solution to the problem of the central slot concealment that is unattainable by other means, such as; Z-plasty and mini-graft. Methods: Authors applied the Frechet technique to Asian patients who had undergone scalp reduction and operated on 4 patients from March, 2000 to January, 2001. Average follow-up period was 13 months. Patients with long scars passing through the temporoparietoccipital zone were excluded. All the undermining was performed in the subgaleal plane, reaching the upper auricular sulcus and stopping just above the nuchal ridge. Results: None of the patients experienced infection, hematoma, nor any permanent hair loss. Transient telogen effluvium at the distal end of flap 2 and 3 was noticeable in one case. Conclusion: In conclusion, the results are aesthetically satisfactory without any significant complications.

• 대한기계학회논문집A
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• 제25권8호
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• pp.1277-1286
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• 2001

Aluminum 5052/Aramid Fiber Reinforced Plastic(Al5052/AFRP) laminates are applied to the fuselage-wing intersection. The Al5052/AFRP laminates suffer from the cyclic bending moment of variable amplitude during the service. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in Al5052/AFRP laminate was investigated in this study. Al5052/AFRP laminate composite consists of three thin sheets of Al5052 and two layers of unidirectional aramid fibers. The cyclic bending moment fatigue tests were performed with five different levels of bending moment. The shape and size of the delamination zone formed along the fatigue crack between Al5052 sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging mechanism and the delamination zone were studied. Fiber failures were not observed in the delamination zone in this study. It represents that the fiber bridging modification factor should turn out to increase and that the fatigue crack growth rate should decrease. The shape of delamination zone turns out to be semi-elliptic with the contour decreased non-linearly toward the crack tip.

• 한국토양비료학회지
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• 제45권3호
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• pp.353-359
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• 2012

The identification of effective root zone would clarify dynamics of plant available water and soil water balance. Using the relationship between soil properties and electrical resistivity (ER) the purpose of this research is to identify soil zone affected by a plant root activity using electrical resistivity tomography (ERT) technique. Four plastic containers were prepared for two different soil textures (clay and sandy loam) and one container for each texture was selected for planting four corn seedlings (Zea mays L.) and the others were prepared for the blank. For ERT monitoring, we prepared 0.8 m plastic sticks with 17 electrodes installed with 5 cm space. The Ministing (AGI Inc., Texas) instrument for electrical resistivity measurement and semi-auto converter of electrode arrangement were set up for dipole-dipole array. During 2 months of the corns growing, ERT monitoring was made 3 to 4 days after the irrigation practice. Despite of the same amount water supplied into soils, two textures showed very different apparent resistivity values due to different clay content. The apparent electrical resistivity is consistently lower in clay loam comparing to sandy loam soil implying that plant root does not significantly alter the overall trend of resistivity. When plant root system, however, is active both soils with plants showed 2-7 times higher electrical resistivity and higher coefficient variation than soils without plant, implying the effect of root system on the resistivity, in which may caused by. This result suggests plant root activities regulating the soil water dynamics mainly control the variation of electrical resistivity over soil textural difference. Therefore the identification of water uptake zone would highly be correlated to plant root activities, thus ERT will be feasible approach to identify spatial characteristics of a plant root activity.

• 한국전산구조공학회논문집
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• 제22권5호
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• pp.487-499
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• 2009

컴퓨터의 성능이 향상되고 해석 알고리즘이 개선될수록 유한요소 모델링은 정교해지고 복잡해지는 경향이 있으며, 그에 상응하여 후처리 기술도 다양하게 발전하게 되었다. 이와같이 하드웨어적, 소프트웨어적인 진전을 바탕으로 탄소성해석에서는 더욱 세분화된 단계적 증분과 반복의 중간 계산 결과를 이용하여 탄소성 거동을 관찰하고 분석하는 것이 실용적인 의미를 갖게 되었다. 이 논문은 유한요소해석을 통해서 얻은 계산 결과로 부터 탄소성 재료의 역학적인 거동을 이론적으로 구성하고, 컴퓨터 그래픽스로 가시화하는 새로운 후처리 방법에 관하여 기술하였다. 또한 소성 거동의 진행을 표현하는 새로운 방법과 해석의 중간단계에서 생성된 데이터를 항복곡면과 응력경로의 형태로 재구성하거나 또는 Mohr원과 파괴포락선의 형태로 재구성하여 탄소성 거동을 분석하고 이해하는 방법을 제안하였다.