• 한국의류산업학회지
• /
• 제18권4호
• /
• pp.520-530
• /
• 2016

This research aims to propose an ergonomic design process for hip protector based on previous studies, existing products, multidisciplinary experts opinion, and wearing test. The elderly are more likely to suffer a hip fracture when they fall due to their physical changes in skeletal form, muscle quantity, bone density, and joint movement. A hip protector is an effective product to prevent hip fractures in the elderly but it also has a problem in that it is uncomfortable. Therefore there is a high chance that it won't be able to prevent hip fractures properly. Since the comfort of a hip protector is one of the most critical elements in preventing a hip fracture, we need to keep improving the hip protector for mobility and usability. Based on the previous studies and limitations of current hip protector products, we need to come up with an optimal design for the Korean elderly. First, knowledge has to be built relating to the ergonomic design of the hip protector considering body shape and size analysis using 3D-scan data, and biomechanical analysis on hip fracture. Second, we need to develop a design process including hip protector pattern design, and wearing evaluation with virtual system. Third, we suggest to reevaluate and verify the design procedure from impact evaluation using testing simulator, virtual evaluation of impact, to wearing comfort and usability evaluation. This design process presented in this study would be expected to contribute to the development of ergonomic hip protector which is suitable for the Korean elderly.

• 마이크로전자및패키징학회지
• /
• 제18권1호
• /
• pp.15-21
• /
• 2011

전자기기의 고집적화를 위해 실리콘 웨이퍼의 두께가 점점 얇아지고 있으며 이로 인해 제조공정 중 균열이나 파손이 발생할 가능성이 높아지고 있다. 본 연구에서는 300 ${\mu}m$~100 ${\mu}m$ 두께의 반도체용 단결정 실리콘 웨이퍼의 파단 강도 및 파괴특성을 평가하였다. 기계적 연마를 통해 두께 (300, 200, 180, 160, 150, 100 ${\mu}m$)가 다른 실리콘 웨이퍼를 준비하였다. 하나의 웨이퍼에서 40개의 실리콘 다이(크기 : 62.5 mm${\times}$4 mm)를 얻어 4점 굽힘시험을 통해 평균 강도값을 구하였다. 강도분포의 통계적 해석을 위해 와이블 선도를 이용하여 형상인자(와이블 계수)와 크기인자(확률적 파괴강도)를 얻었다. 취성 실리콘 다이의 시편 크기(두께)효과와 파단 확률이 고려된 통계적 파단강도 값을 실리콘 다이 두께의 함수로 얻었다. 관찰된 파괴양상을 측정된 파단강도와 관련하여 고찰하였다.

• Restorative Dentistry and Endodontics
• /
• 제26권5호
• /
• pp.399-408
• /
• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• 대한정형외과 초음파학회지
• /
• 제6권2호
• /
• pp.60-64
• /
• 2013

원위 요골 골절에 대한 수장부 금속판 고정술이 많이 사용되면서, 합병증으로서, 원위 요골 배측 피질골을 관통한 나사못으로 인해 신전건 활막염이나 파열이 발생할 수 있슴이 보고된 바 있다. 그러나, 나사못에 의한 배측 피질골의 관통여부를 표준 방사선 촬영만으로 정확히 평가하기에는 한계가 있다. 저자들은 수장측 금속판 고정술 후 발생한 신전건 건활막염 및 부분 파열이 의심된 환자에 대하여 수술 전 초음파를 이용하여 나사못에 의한 건활막염 및 활막 종괴 형성 소견을 효과적으로 진단하고 수술적 치료를 시행하여 좋은 결과를 얻었기에 이를 보고하고자 한다.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제27권6호
• /
• pp.535-544
• /
• 2005

The management of mandibular condyle fractures continues to be a subject of much debate. It is suggested that, if not properly managed, these fractures may give rise to serious problems, such as malocclusion, mouth opening limitation, temporomandibular joint disorders. Treatment planing of mandibular condyle fractures is very important. The aim of this present study was to evaluate the long-term results according to treatment methods in condylar fractures. Also, it was to evaluate results of treatment according to condylar fracture level. We conducted a retrospective analysis of 43 mandibular condyle fractures. 43 patients followed for average period of 9.00 years(mini. 7yr, max. 12yr). All patients underwent a clinical and radiologic evaluation focusing on mouth opening, mandibular movements, TMJ function, change of ramal height, condylar remodelling. If the level of fracture was positioned in high, especially in level II, mandibular movement disability and ramus length loss was more prominent. This results were similar to the cases of treatment of fragment removal. In high level fracture and fragment removal cases, It is thought that more intensive and long term management are needed than other treatment cases using different operation methods. Also, direct fixation by each approach showed good results in mandibular movement, ramal height change and condylar shape. Through this results, accurate reduction of the mandibular condyle fractures was a very important factor in postoperative prognosis.

• Structural Engineering and Mechanics
• /
• 제17권1호
• /
• pp.51-68
• /
• 2004

Since the linear elastic fracture analysis has been proved to be insufficient in predicting the failure of strain hardening materials, a number of fracture concepts have been studied which remain applicable in the presence of plasticity near a crack tip. This work thereby presents a new finite element model to predict the elastic-plastic crack-tip field and fatigue life of center-cracked panels(CCP) with ductile fracture under large-scale yielding conditions. Also, this study has been carried out to investigate the path-dependence of J-integral within the plastic zone for elastic-perfectly plastic, bilinear elastic-plastic, and nonlinear elastic-plastic materials. Based on the incremental theory of plasticity, the p-version finite element is employed to account for the accurate values of J-integral, the most dominant fracture parameter, and the shape of plastic zone near a crack tip by using the J-integral method. To predict the fatigue life, the conventional Paris law has been modified by substituting the range of J-value denoted by ${\Delta}J$ for ${\Delta}K$. The experimental fatigue test is conducted with five CCP specimens to validate the accuracy of the proposed model. It is noted that the relationship between the crack length a and ${\Delta}K$ in LEFM analysis shows a strong linearity, on the other hand, the nonlinear relationship between a and ${\Delta}J$ is detected in EPFM analysis. Therefore, this trend will be depended especially in the case of large scale yielding. The numerical results by the proposed model are compared with the theoretical solutions in literatures, experimental results, and the numerical solutions by the conventional h-version of the finite element method.

• 대한조선학회논문집
• /
• 제56권4호
• /
• pp.335-342
• /
• 2019

The objective of this study is to analyze the mechanical properties of plywood used as a thermal insulating material for LNG CCS (Liquefied Natural Gas, Cargo Containment System). It is created by bonding an odd number of parallel and perpendicular direction for preventing contraction and expansion of wood. Also plywood is widely used as LNG CCS insulating material because of its durability, light weight and high stiffness. Since LNG CCS is loaded with liquid cargo, the impact load by sloshing during operation and the wide temperature range (room temperature, low temperature, cryogenic temperature) exposed during loading, unloading should be considered. The thickness of the plywood which is used for the membrane type MARKIII was selected as the thickness of the test specimen. In this present study, plywood is analyzed by the fracture behavior and mechanical properties of plywood by temperature and grain direction. In addition, it is necessary to analyze the fracture shape and predict the fracture strain by using regression model because the critical load may cause cracks inside the tank, which may affect the leakage of cryogenic liquid.

• Composites Research
• /
• 제19권4호
• /
• pp.15-22
• /
• 2006

구조물 설계에 복합재료-금속 접착제 결합 조인트의 개발 및 사용을 제한하는 가장 큰 요인은 접착 조인트의 하중지지 능력 예측을 위한 접착 계면의 강도 평가 방법의 부재이다. 본 연구에서는 복합재료-탄소강의 접착 강도를 계면 모서리에서의 응력강도계수와 파괴 인성 값으로 평가하였다. 구체적으로 동시 경화 성형법으로 제작된 복합재료-탄소강 양면 겹치기 접착조인트의 하중지지 능력을 파괴 역학적 분석 방법을 통하여 결정하였다. 이종재료 계면 모서리 첨단의 응력 특이성과 그 지수를 제시하고 최종적으로 응력강도계수와 실험을 통한 계면의 파괴인성 값을 획득하였다. 서로 다른 접합 길이를 갖는 조인트의 하중지지 능력 비교를 통하여 양면 겹치기 접착 조인트의 파괴 인성치와 혼합 모드에서의 균열 진전 기준을 $K_1-K_{11}$ 평면 내에 도시하였다.

• Journal of Welding and Joining
• /
• 제5권1호
• /
• pp.64-72
• /
• 1987

The Weldability of gavannealed steel using spot welder has been studied. The Results obtained are a follows; 1) Welds size and strength were increased depending on the welding time and welding current. But, the increasing rate has been decreased. 2) Deposited zinc has affected on the wear of welding tips and growth of welds but has not affected the weld's structures. 3) On shear testing of the specimen, button fracture has been observed and the value was approximately 540Kg (welds dia. approximately .phi.4mm)

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
• /
• pp.935-940
• /
• 2002

This paper presents the failure mode on Headed Bars and prediction of tensile capacity, which is governed by concrete cone failure. 17 different plate types, three different concrete strengths and three different welding types of specimens were simulated. Static tensile load was applied Headed Bars were manufactured in different areas, and their shape and thickness are based on ASTM 970-98. Calculation of embedment length in concrete is conducted based on CSA 23.3-94, and static tensile load was applied. Tested pullout capacities were compared to the values determined using current design methods such as ACI-349 and CCD method.