• Journal of Mechanical Science and Technology
• /
• 제19권10호
• /
• pp.1919-1931
• /
• 2005

Human joint motion can be kinematically described in three planes, typically the frontal, sagittal, and transverse, and related to experimentally measured data. The selection of reference systems is a prerequisite for accurate kinematic analysis and resulting development of the equations of motion. Moreover, the development of analysis techniques for the minimization of errors, due to skin movement or body deformation, during experiments involving human locomotion is a critically important step, without which accurate results in this type of experiment are an impossibility. The traditional kinematic analysis method is the Angular-based method (ABM), which utilizes the Euler angle or the Bryant angle. However, this analysis method tends to increase cumulative errors due to skin movement. Therefore, the objective of this study was to propose a new kinematic analysis method, Position-based method (PBM), which directly applies position displacement data to represent locomotion. The PBM presented here was designed to minimize cumulative errors via considerations of angle changes and translational motion between markers occurring due to skin movements. In order to verify the efficacy and accuracy of the developed PBM, the mean value of joint dislocation at the knee during one gait cycle and the pattern of three dimensional translation motion of the tibiofemoral joint at the knee, in both flexion and extension, were accessed via ABM and via new method, PBM, with a Local Reference system (LRS) and Segmental Reference system (SRS), and then the data were compared between the two techniques. Our results indicate that the proposed PBM resulted in improved accuracy in terms of motion analysis, as compared to ABM, with the LRS and SRS.

• Computers and Concrete
• /
• 제18권6호
• /
• pp.1083-1096
• /
• 2016

Beam-column joints are recognized as the weak points of reinforcement concrete frames. The ductility of reinforced concrete (RC) frames during severe earthquakes can be measured through the dissipation of large energy in beam-column joint. Retrofitting and rehabilitating structures through proper methods, such as carbon fiber reinforced polymer (CFRP), are required to prevent casualties that result from the collapse of earthquake-damaged structures. The main challenge of this issue is identifying the effect of CFRP on the occurrence of failure in the joint of a cross section with normal ductility. The present study evaluates the retrofitting method for a normal ductile beam-column joint using CFRP under monotonic and cyclic loads. Thus, the finite element model of a cross section with normal ductility and made of RC is developed, and CFRP is used to retrofit the joints. This study considers three beam-column joints: one with partial CFRP wrapping, one with full CFRP wrapping, and one with normal ductility. The two cases with partial and full CFRP wrapping in the beam-column joints are used to determine the effect of retrofitting with CFRP wrapping sheets on the behavior of the beam-column joint confined by such sheets. All the models are subjected to monotonic and cyclic loading. The final capacity and hysteretic results of the dynamic analysis are investigated. A comparison of the dissipation energy graphs of the three connections shows significant enhancement in the models with partial and full CFRP wrapping. An analysis of the load-displacement curves indicates that the stiffness of the specimens is enhanced by CFRP sheets. However, the models with both partial and full CFRP wrapping exhibited no considerable improvement in terms of energy dissipation and stiffness.

• 대한한의학회지
• /
• 제17권2호
• /
• pp.296-302
• /
• 1996

Pericarpium Citri Nobilis Viride, a traditional herb medicine, has been used in Korea and China for many centuries as a treatment for respiratory disease. The purpose of the present study was to determine the effect of Pericarpium Citri Nobilis Viride on histamine-induced tracheal smooth muscle contraction in rats. Guinea pigs(500g , female) were killed by $CO_2$ exposure and a segment (8-10mm) of the thoracic trachea from each guinea pig was cut into equal segments and mounted 'in pairs' in a tissue bath. Contractile force was measured with force displacement transducers under 0.5g loading tension. The dose of histamine which evoked 50% of maximal response $(ED_{50})$ was obtained from cumulative dose response curves for histamine $(10^{-7}-10^{-4}M)$. Contractions evoked by histamine ($ED_{50}$) were inhibited significantly by Pericarpium Citri Nobilis Viride. The mean percent inhibition was 53.7% (P<0.05) after 1.5mg／ml Pericarpium Citri Nobilis Viride, and 87.7% (P<0.01) after 5.0mg／ml Pericarpium Citri Nobilis Viride. Propranolol $(10^{-7}M)$ slightly but significantly attenuated the inhibitory effects of Pericarpium Citri Nobilis Viride. Following treatment with propranolol the mean present inhibition caused by 1.5 and 5.0mg／ml Pericarpium Citri Nobilis Viride. Indomethacin and methylene blue $(10^{-7}M)$ did not significantly alter the inhibitory effect of Pericarpium Citri Nobilis Viride These results indicate that Pericarpium Citri Nobilis Viride can relax histamine-induced contraction of guinea pig tracheal smooth muscle, and that this inhibition involves in part symphathetic nerve system.

• 한국항행학회논문지
• /
• 제18권4호
• /
• pp.381-386
• /
• 2014

전기 커넥터에 영향을 주는 프레팅 부식 요인 중 하나인 접촉 부하의 영향을 조사하기 위하여, 프레팅 부식 표본 쌍을 두께 $3{\mu}m$의 두께를 갖는 주석으로 도금된 황동 표본을 사용하여 제조하였다. 접점의 전기저항은 프레팅 부식 시험 기간 동안 측정되었다. 프레팅 주기에서 저항은 증가하였다. 저항의 변화는 3단계로 나눌 수 있다. 첫 번째 단계는 미미하고 안정적인 저항을 나타내었다. 두 번째 단계는 저항이 꾸준한 증가를 보여 주었다. 그리고 세 번째 단계는 매우 높고 간헐적인 저항을 보여주었다. 실패주기(Nf)와 접촉력(P) 사이의 관계는 다음과 같이 표현될 수 있다. 각각의 하중, 변위, 온도 등 다양한 조건에서 프레팅 테스트를 통해 다양한 환경 조건 하에서 매우 높고 간헐적인 저항에 대응 전기 커넥터의 실패주기 예측공식의 표현이 가능할 것이다.

• Journal of Korean Neurosurgical Society
• /
• 제46권2호
• /
• pp.144-151
• /
• 2009

Objective: To compare two testing protocols for evaluating range of motion (ROM) changes in the preloaded cadaveric spines implanted with a mobile core type Charite$^{TM}$ lumbar artificial disc. Methods: Using five human cadaveric lumbosacral spines (L2-S2), baseline ROMs were measured with a bending moment of 8 Nm for all motion modes (flexion/extension, lateral bending, and axial rotation) in intact spine. The ROM was tracked using a video-based motion-capturing system. After the Charite$^{TM}$ disc was implanted at the L4-L5 level, the measurement was repeated using two different methods: 1) loading up to 8 Nm with the compressive follower preload as in testing the intact spine (Load control protocol), 2) loading in displacement control until the total ROM of L2-S2 matches that when the intact spine was loaded under load control (Hybrid protocol). The comparison between the data of each protocol was performed. Results: The ROMs of the L4-L5 arthroplasty level were increased in all test modalities (p < 0.05 in bending and rotation) under both load and hybrid protocols. At the adjacent segments, the ROMs were increased in all modes except flexion under load control protocol. Under hybrid protocol, the adjacent segments demonstrated decreased ROMs in all modalities except extension at the inferior segment. Statistical significance between load and hybrid protocols was observed during bending and rotation at the operative and adjacent levels (p< 0.05). Conclusion: In hybrid protocol, the Charite$^{TM}$ disc provided a relatively better restoration of ROM, than in the load control protocol, reproducing clinical observations in terms of motion following surgery.

• Journal of Oral Medicine and Pain
• /
• 제17권2호
• /
• pp.63-73
• /
• 1992

This study was performed for the purpose of investigating the relation between width of temporomandibular joint space and craniofacial morphology in patients with CMDs. The subjects utilized here were aged from 16 to 63 years old and 19 male and 46 female. For the study, each patient was taken radiographs by Transcranial and Lateral Cephalographic projection and the films were traced with routine method. The measured items were anterior, superior, posterior joint space and relative condylar position to the deepest part of glenoid fossa in Transcranial film and items related vertical and/or horizontal growth in Cephalogram. The data were processed with SPSS/PC+ package for statistical analysis. The obtained results were as follows : 1. Anterior joint space in affected side were wider than that of unaffected side, but for superior and posterior joint space, the value of unaffected side were more than those of affected side. 2. Superior or posterior joint space of affected side were significantly correlated with items related vertical growth, such as ramus height, Jarabak ratio, FMA. From this, the following cold be proposed, the wider the joint space of superior or posterior aspect of affected side was, the more the patient showed growth pattern of counter clockwise. 3. Superior or posterior joint space of affected side were significantly correlated with items related horizontal growth, such as SNPo, NAPo, APDI and ANB. From this the following could be proposed, the wider the joint space of superior or posterior aspect of affected side was, the more the patient showed anterior displacement of mandible. 4. It would be proposed that the diagnositic value of superior and posterior joint space of affected side in transcranial radiograph was excellent.

• 한국구조물진단유지관리공학회 논문집
• /
• 제17권1호
• /
• pp.46-54
• /
• 2013

실제 교량의 바닥판에 적용할 목적으로 섬유의 길이 및 혼입량을 달리한 두 가지 초고성능 시멘트 복합체를 고려하고 있다. 이 연구의 목적은 이 두 재료의 균열저항성을 평가하는 것이다. 두 재료에 대한 휨인장 파괴실험을 수행하였고, 실험으로부터 얻은 하중-균열개구변위 관계를 최적으로 모사하는 인장응력-균열개구 관계를 역해석을 통해 파악하였다. 역해석결과 13 mm 길이의 섬유를 2% 함유한 UHPCC는 16.3 mm와 19.5 mm 길이의 섬유를 각각 0.5%와 1.0% 함유한 UHPCC에 비해 파괴에너지가 작은 것으로 나타났다. 균열을 보다 분산시키고 균열폭을 감소시키기 위해서는 길이가 긴 두 종류의 섬유를 혼용한 UHPCC를 사용하는 것이 바람직할 것으로 판단된다.

• Composites Research
• /
• 제16권3호
• /
• pp.9-17
• /
• 2003

타이어 벨트층내의 코드간 균열연결 및 층간균열진전을 모사하기 위해 자유단을 갖는 2층 고무/코드 적층시험편에 대한 4~11mm 변위제어 실험을 수행하였다. 자유단의 코드간 균열연결시의 폭방향 균열진전량은 45$^{\circ}$ 경사진 코드들간 길이의 절반에 도달할 때의 측정값으로 하였으며, 이는 탐침법에 의해 측정되었다 또한, 자유단에서 코드들간 균열연결을 모사하기위해 2차원의 이상화된 모델링 기법을 고안하였다. 이론수명은 테어링에너지(균열파단면의 단위면적당 방출에너지)를 이용하여 코드간 균열연결수명(임계값)과 이후 최종파손까지의 수명으로 구분하였으며, 이들을 각기 실험값과 비교하였다. 임계값까지의 수명예측은 실험과 비교하여 약 20%, 최종파손까지 약 65%의 오차가 발생하였다. 따라서, 전체 이론수명은 실험과 비교하여 약 45%의 오차를 발생하였다.

• 한국자동차공학회논문집
• /
• 제22권2호
• /
• pp.100-106
• /
• 2014

Lower control arm (LCA) is a part of chassis in automotive. Performances of LCA such as stiffness, durability and permanent displacement must be considered in design optimization. However it is hard to consider different performances at once in optimization because these are measured by different commercial tools like Radioss, Abaqus, etc. In this paper, firstly, we construct the integrated design automation system for LCA based on Matlab including Hypermesh, Radioss and Abaqus. Secondly, Akaike information criterion (AIC) is used for assessment of reliability of LCA. It can find the best estimated distribution of performance from limited and discrete stochastic information and then obtains the reliability from the distribution. Finally, we consider tolerances of design variables and variation of elastic modulus and achieve the target reliability by carrying out reliability-based design optimization (RBDO) with the integrated system.

• 대한족부족관절학회지
• /
• 제18권1호
• /
• pp.24-28
• /
• 2014

Purpose: The purpose of this study is to evaluate the clinical and radiographic results of internal fixation using multiple Kirschner wires (K-wires) for the fifth metatarsal base fracture. Materials and Methods: We retrospectively reviewed 14 patients with a displaced fifth metatarsal base fracture. We measured the distance of fracture displacement on the foot oblique radiograph pre- and post-operatively. We evaluated the clinical results using the visual analog pain scale at six weeks and three months postoperatively and the American Orthopaedic Foot and Ankle Society (AOFAS) mid-foot score at six months postoperatively. Results: In our series, 10 cases were zone I fracture and four cases were zone II fracture. We achieved anatomical reduction and bony union in all of our cases. The average time to bone union was 43 days. The degree of pain around the fifth metatarsal base was significantly decreased after surgery. The average AOFAS score was 95 at six months postoperatively. Conclusion: Multiple K-wire fixation is a relatively simple fixation method for displaced fifth metatarsal base fractures. If we place a K-wire into the medial cortex of the fifth metatarsal, we could prevent proximal migration of the K-wire.