• Composites Research
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• 제32권5호
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• pp.249-257
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• 2019

In this paper, the buckling behavior of triaxially braided circular arch with monosymmetric open section subjected to three-point bending was studied experimentally and numerically. First, test specimens were manufactured using vacuum assisted resin transfer molding (VARTM). Then the specimen was tested under three-point bending to determine the ultimate buckling strength. Before performing the numerical analysis, effective material properties of the braided composite were obtained through micro-meso scale analysis virtual testing validated with available test results. Then linear buckling analysis and geometrically non-linear post buckling analysis, established to simulate the test setup, were performed to study the buckling behavior of the composite frame. Analysis results were compared with experimentally obtained ones for verification. The effect of manufacturing defects of tow misalignment, irregular surface and resin rich region, and uncertainties during test setup were studied using numerical models. From the numerical analyses performed it was observed that both manufacturing defect and uncertainties had effect on the buckling behavior and strength.

• Archives of Plastic Surgery
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• 제41권6호
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• pp.709-715
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• 2014

Background The distally based sural artery flap is a reliable, local reconstructive option for small soft tissue defects of the distal third of the leg. The purpose of this study is to describe an adipofascial flap based on a single sural nerve branch without sacrificing the entire sural nerve, thereby preserving sensibility of the lateral foot. Methods The posterior aspect of the lower limb was dissected in 15 cadaveric limbs. Four patients with soft tissue defects over the tendo-achilles and ankle underwent reconstruction using the adipofascial flap, which incorporated the distal peroneal perforator, short saphenous vein, and a single branch of the sural nerve. Results From the anatomical study, the distal peroneal perforator was situated at an average of 6.2 cm (2.5-12 cm) from the distal tip of the lateral malleolus. The medial and lateral sural nerve branches ran subfascially and pierced the muscle fascia 16 cm (14-19 cm) proximal to the lateral malleolus to enter the subcutaneous plane. They merged 1-2 cm distal to the subcutaneous entry point to form the common sural nerve at a mean distance of 14.5 cm (11.5-18 cm) proximal to the lateral malleolus. This merging point determined the pivot point of the flap. In the clinical cases, all patients reported near complete recovery of sensation over the lateral foot six months after surgery. All donor sites healed well with a full range of motion over the foot and ankle. Conclusions The distally based sural artery adipofascial flap allowed for minimal sensory loss, a good range of motion, an aesthetically acceptable outcome and can be performed by a single surgeon in under 2 hours.

• 정보관리연구
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• 제39권2호
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• pp.95-130
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• 2008

본고는 전자기록 환경에서의 국가 평가체계 정비 방향을 모색하기 위한 시론적 연구로서의 의미를 지닌다. 전자기록 환경에서의 필연적인 평가방식이라 할 수 있는 기능평가는 국가적 차원의 영구보존 기록 선별에는 일정 한계를 지닌다. 이에 본고에서는 우선 기능평가가 지닌 한계를 논의한 다음, 이를 보완하기 위한 방안으로 영구보존 대상 평가전략의 필요성을 제기하였다. 그리고 이에 대한 구체적인 사례를 고찰하기 위해, 호주의 범정부 기능분석, 영구의 평가정책 및 수집정책, 독일의 다기관협력 평가전략, 캐나다의 거시평가 전략을 분석하였다. 결국 이러한 분석은 현용 가치와 사회적 가치가 조화된 국가 평가체계의 토대를 제공해주게 된다.

• Journal of applied mathematics & informatics
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• 제30권3_4호
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• pp.365-380
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• 2012

Non-negative matrix factorization (NMF) is a very efficient method to explain the relationship between functions for finding basis information of multivariate nonnegative data. The multiplicative update (MU) algorithm is a popular approach to solve the NMF problem, but it fails to approach a stationary point and has inner iteration and zero divisor. So the elementwisely alternating projected gradient (eAPG) algorithm was proposed to overcome the defects. In this paper, we use the fact that the equilibrium point is stable to prove the convergence of the eAPG algorithm. By using a classic model, the equilibrium point is obtained and the invariant sets are constructed to guarantee the integrity of the stability. Finally, the convergence conditions of the eAPG algorithm are obtained, which can accelerate the convergence. In addition, the conditions, which satisfy that the non-zero equilibrium point exists and is stable, can cause that the algorithm converges to different values. Both of them are confirmed in the experiments. And we give the mathematical proof that the eAPG algorithm can reach the appointed precision at the least iterations compared to the MU algorithm. Thus, we theoretically illustrate the advantages of the eAPG algorithm.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.51-56
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• 2000

Demand for new nondestructive evaluations is growing to detect tensile crack growth behavior to predict long term performance of materials and structure in aggressive environments, especially when they are in non-visible area. Acoustic emission technique is well suited to these problems and has drawn a keen interests because of its dynamic detection ability, extreme sensitivity and location of growing defects. In this study, we analysed acoustic emission signals obtained in tensile test of high strength fire resistance steel for frame structure with time frequency analysis methods. The results obtained are summaries as follows ; In the T and TN specimen consisting of ferrite and pearlite grains, most of acoustic emission events were produced near yield point, mainly due to the dislocation activities during the deformation. However, B specimen under $600^{\circ}C$ - 10min had a two peak which was attribute to the presence of martensite phase. The first peak is before yield point the second is after yield point. The sources of second acoustic emission peak were the debonding of martensite-martensite interface and the micro-cracking of brittle martensite phase. In $600^{\circ}C$-30min to $700^{\circ}C$-60min specimens, many signals were observed from area before yield point and counts were decreased after yield point.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제18권4호
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• pp.746-757
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• 1996

Bony defects may be found as a result of congenital anomalies, traumatic injury, automobile collisions and industrial accidents in the maxillofacial area. Such conditions are often associated with severs functional and esthetic problem. Various surgical procedure has been utilized in attempts to repair and reconstruct bony defects. Bone is a complex, living, constantly changing tissue. The architecture and composition of cancellous and cortical bone allow the skeleton to perform its essential mechanical functions. Periosteum covers the external surface of bone and consists of two layers : an outer fibrous layer and an inner more cellular and vascular layer. The inner osteogenic layer or cambium layer can form new bone while the outer layer firms part of the insertions of tendons, ligaments and muscles. This study was under taken to evaluate bone healing process on partial defect of calvarial bone with or without periosteum in rat. We made calvarial defects of different size(4mm, 6mm, 8mm) with periosteum or without periosteum in rat to study the effect of defect size on healing process. Control and experimental groups sacrified at 1, 2, 4, 6, 8 weeks, postoperatively. We examed the specimens by gloss findings, light microscophy, and fluorescent microscophy. The results were as follows. 1. Gloss findings: Control groups are larger bony defects than experimental groups after 2 weeks, and than control groups advanced healing of defected bone but experimental groups are lesser after 4, 6 weeks. After 8 weeks, bone defect has not been identified in control and experimental groups. 2. Light microscope: All defects of control groups are larger bony defects than experimental groups after 2 weeks. And than control groups show smaller defect after 4 weeks. After 8 weeks, the control group reveal pin-point sized, hardly identifiable defect space and the experimental group reveal small, but definite defect space. 3. Fluorescent microscope : Each week, new bone formation of control group is very similar to the experimental group. In this study, Osteogenesis of calvarial bone defects with periosteum or without periosteum was examined for 8 weeks in rats. The replaced periosteum had batter new bone formation than the removed periosteum.

• Archives of Reconstructive Microsurgery
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• 제21권2호
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• pp.143-148
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• 2012

Purpose: This report presents the authors' experience of twelve patients with sural artery flap for soft tissue defects around the knee joint. Materials and Methods: The patients' age ranged from 25 to 80 years; seven of the patients were male and five were female. The cause of soft-tissue defects involved wide excision for malignant soft tissue tumor, tumor prosthesis related infection, infection after total knee arthroplasty and chronic osteomyelitis. Postoperative range of motion was checked. The sensibility of flap was evaluated by Semmes-Weinstein monofilaments and two-point discrimination. Results: All flaps survived and provided satisfactory coverage of the defect. There was no complication except one delayed skin graft incorporation at donor site. Seven knee joints which had been stiff previously gained average 58 degrees of ROM postoperatively. All flaps retained sensibility and showed no significant increase in sensory thresholds comparing with contralateral side. Conclusion: Sural artery flap not only shows high survival rate and broad coverage ability, but also offers improvement in range of motion and preservation of sensation. We speculate that sural artery flap is valuable for the reconstruction of the soft tissue defects around knee joint.

• Journal of Welding and Joining
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• 제13권2호
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• pp.42-52
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• 1995

In the evaluation of aging degradation on the structural materials based on the fracture mechanics, the detection and size prediction of defect are very important. Aiming at nondestructive detection and size prediction ol defect with high accuracy and resolution, therefore, an lnduced Current Focusing Potential Drop(ICFPD) technique has been developed. The principle of this technique is to induce a focusing current at an exploratory region by an induction wire flowing an alternating current(AC) that is a constant ampere and frequency. Defects are assessed with the potential drops that are measured the induced current on the surface of metallic material by the potential pick-up pins. In this study, the lCFPD technique was applied for evaluating the location and size of the surface crack and blind crack made in plate specimens, and also for detecting the defects existing in valve, a field component, that were developed by SCC etc. during the service. The results of this present study show that surface crack and blind crack are able to defect with potential drop. these cracks are distinguished with the distribution of potential drop, and the crack depths can be estimated with each normalized potential drop that are parameters estimating the depth of each type crack. In the field component, the defects estimated by experiment result correspond with those in the cutting face of the measuring point within a higher sensitivity.

• Archives of Reconstructive Microsurgery
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• 제10권2호
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• pp.163-168
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• 2001

The defects of the abdominal wall could be brought about either congenitally, for instances in such cases as omphalocele or gastroschisis, or by various acquired causes-trauma, excision of tumors, excision of burn scar, tissue necrosis caused by infection, hematoma after abdominal surgery, tissue necrosis after radiation therapy and so on. As for the techniques of the reconstruction of the abdominal wall defects, many authors have developed and reported diverse methods. To summarize, primary closure, skin graft, local skin flaps, various myocutaneous flaps, free flap, fascia graft, artificial mesh, tissue expansion, etc could be used in the reconstruction of the abdominal wall defects. The periumbilical perforator-based island skin flap has a many advantages such as no significant sacrifice of the rectus abdominis muscle, wide rotation arc, reliable blood flow of the perforator, short elevation time for flap, and for middle-aged, obese patients, the donor site may be the best from the cosmetic point of view. We used perforator-based island skin flap in 5 cases with reasonable result from March 1999 to May 2001. There were no significant complications and donor sites could be repaired primarily.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제7권7호
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• pp.249-258
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• 2018

국방 무기체계에서의 소프트웨어 비중이 증가하고 있으며 구조도 점차 복잡해지고 있어, 이에 따른 신뢰성 검증이 매우 중요하다. 특히 무기체계 시스템을 구성하는 소프트웨어 구성 요소 들의 상호 작용에 따라 발생하는 결함은 정적 시험 및 코드 실행률 점검 수준의 동적 시험만으로는 예방하기가 어렵다. 본 논문에서는 소프트웨어의 동적 결함 유형을 분류 개발한다. 미 국방부 무기체계에 사용하는 오픈 소스 소프트웨어(OSS)에서 보고된 이슈 분석을 통하여 본 논문에서 분류한 동적 결함이 실제로 발생하며, 이들은 대체로 통합 이후 발생하는 결함이며, 재현이 어렵고, 결함 원인 파악이 어려웠음을 보인다. 이 분석 결과를 기반으로 무기체계 신뢰성 검증을 위하여 소프트웨어 통합 시험 개선의 중요성을 도출한다.