• Advances in aircraft and spacecraft science
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• 제11권1호
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• pp.83-103
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• 2024

Adhesive bonding is currently widely used in many industrial fields, particularly in the aeronautics sector. Despite its advantages over mechanical joints such as riveting and welding, adhesive bonding is mostly used for secondary structures due to its low peel strength; especially if it is simultaneously exposed to temperature and humidity; and often presence of bonding defects. In fact, during joint preparation, several types of defects can be introduced into the adhesive layer such as air bubbles, cavities, or cracks, which induce stress concentrations potentially leading to premature failure. Indeed, the presence of defects in the adhesive joint has a significant effect on adhesive stresses, which emphasizes the need for a good surface treatment. The research in this field is aimed at minimizing the stresses in the adhesive joint at its free edges by geometric modifications of the ovelapping part and/or by changing the nature of the substrates. In this study, the finite element method is used to describe the mechanical behavior of bonded joints. Thus, a three-dimensional model is made to analyze the effect of defects in the adhesive joint at areas of high stress concentrations. The analysis consists of estimating the different stresses in an adhesive joint between two 2024-T3 aluminum plates. Two types of single lap joints(SLJ) were analyzed: a standard SLJ and another modified by removing 0.2 mm of material from the thickness of one plate along the overlap length, taking into account several factors such as the applied load, shape, size and position of the defect. The obtained results clearly show that the presence of a bonding defect significantly affects stresses in the adhesive joint, which become important if the joint is subjected to a higher applied load. On the other hand, the geometric modification made to the plate considerably reduces the various stresses in the adhesive joint even in the presence of a bonding defect.

• 대한수학회지
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• 제42권3호
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• pp.517-527
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• 2005

This paper considers a discrete-time queueing system with variable service capacity. Using the supplementary variable method and the generating function technique, we compute the joint probability distribution of queue length and remaining service time at an arbitrary slot boundary, and also compute the distribution of the queue length at a departure time.

• 대한정형도수물리치료학회지
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• 제21권1호
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• pp.29-35
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• 2015

Background: The purpose of this study was conducted to investigate the effect of incidence of ankle sprains on both leg length inequalities and range of motion of ankle joint in 20's female university students. Methods: 20's female university students were targeting 32 people attending K university in Gwangju. Both leg length inequality was measured using a tape measure, ranges of motion of ankles was measured using a goniometer. Results: The ankle sprain incidence was quite high, with 56.25% (n=18) for the right ankle, 34.38% (n=11) for the left ankle, and 9.38% (n=3) for both. As for the difference between the ankle sprain incidence and both leg length, the average value of the right leg was $83.08{\pm}3.69$, the average value of the left leg was $84.28{\pm}3.27$, making the right leg shorter than the left by 1.2cm with a higher incidence and showing a positive statistical correlation between the two (p<.05). Also showed that there was a negative statistical correlation between ankle sprain incidences and the inversion range of motion spread of the right ankle (p<.05). Conclusion: The incidence of ankle sprains was higher for the larger the difference between both leg length inequality. In addition, the smaller the inversion range of motion spread of the right ankle, the higher the incidence of ankle sprains. Therefore, The evidence suggests that the incidence of ankle sprains can be reduced by recommending stability and efficient exercises that take into consideration the both leg length as well as the ranges of motion of ankle joints.

• 소음진동
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• 제9권5호
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• pp.975-983
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• 1999

This paper describes the dynamic characteristics of the joint structures in case of using the simplified beam model in the F. E. analysis. The modeling errors, when replace the shell with the beam, are investigated through F. E. normal modes analysis. Normal mode analysis were performed to obtain the natural frequencies of the L and T shaped joints with various type of channels. The results were analyzed to access the effects of the models on the accuracy of F.E. analysis by identifying the geometric factors which cause the error. The geometric factors considered are joint angle, channel length, thickness and area ratio of the hollow section to the filled one. The joint stiffness evaluation technique is developed in this study using normal modes analysis with Lumped Mass. With this method, the progressively improved results of F. E. analysis are obtained using the simplified beam model. The static and normal modes analysis are performed with the joint stiffness values obtained by the Kazunori Shimonkakis' virtual stiffness method and the proposed method and these simplified modeling errors are compared.

• Steel and Composite Structures
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• 제47권1호
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• pp.19-36
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• 2023

An experimental study of eleven PVC-FRP Confined Concrete (PFCC) column-Reinforced Concrete (RC) beam joints reinforced with Core Steel Tube (CST) under axial compression is carried out. All specimens are designed in accordance with the principle of "weak column and strong joint". The influences of FRP strips spacing, length and steel ratio of CST, height and stirrup ratio of joint on mechanical behavior are investigated. As the design anticipated, all specimens are destroyed by column failure. The failure mode of PFCC column-RC beam joint reinforced with CST is the yielding of longitudinal steel bars, CST and stirrups of column as well as the fracture of FRP strips and PVC tube. The ultimate bearing capacity decreases as FRP strips spacing or joint height increases. The effects of other three studied parameters on ultimate bearing capacity are not obvious. The strain development rules of longitudinal steel bars, PVC tube, FRP strips, column stirrups and CST are revealed. The effects of various studied parameters on stiffness are also examined. Additionally, an influence coefficient of joint height is introduced based on the regression analysis of test data, a theoretical formula for predicting bearing capacity is proposed and it agrees well with test data.

• 한국융합학회논문지
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• 제9권8호
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• pp.179-184
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• 2018

자동차의 구동방식은 전륜구동, 후륜구동, 4륜구동의 방식이 있다. 구동방식에서 운전자가 원하는 방향으로 전환하는 것과 바퀴에 동력을 전달하여 구동하는 두 가지의 역할을 수행하는데 있어 가장 중요한 부품이 등속 조인트이다. 도로상에서 주행 시에는 노면의 상태에 따라서 동력을 전달하는 부품들에 충격이 가해질 수 있다. 본 연구에서는 각각 샤프트의 길이가 다른 3개의 등속 조인트 각 모델들은 CATIA로 모델링하였고 ANSYS를 이용하여 구조 및 피로해석을 수행하였다. 본 연구 결과로는 Model 2가 다른 모델 대비 뛰어난 내구성을 가짐을 알 수 있었다. 이러한 결과를 이용하여 충격에 대한 내구성을 가지는 등속 조인트 설계를 할 때에 유용한 자료가 될 것이라고 사료되며, 등속 조인트의 디자인을 융합기술에 접목하여 미적 감각을 나타낼 수 있다.

• Advances in biomechanics and applications
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• 제1권3호
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• pp.169-185
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• 2014

Computational multibody models of the elbow can provide a versatile tool to study joint mechanics, cartilage loading, ligament function and the effects of joint trauma and orthopaedic repair. An efficiently developed computational model can assist surgeons and other investigators in the design and evaluation of treatments for elbow injuries, and contribute to improvements in patient care. The purpose of this study was to develop an anatomically correct elbow joint model and validate the model against experimental data. The elbow model was constrained by multiple bundles of non-linear ligaments, three-dimensional deformable contacts between articulating geometries, and applied external loads. The developed anatomical computational models of the joint can then be incorporated into neuro-musculoskeletal models within a multibody framework. In the approach presented here, volume images of two cadaver elbows were generated by computed tomography (CT) and one elbow by magnetic resonance imaging (MRI) to construct the three-dimensional bone geometries for the model. The ligaments and triceps tendon were represented with non-linear spring-damper elements as a function of stiffness, ligament length and ligament zero-load length. Articular cartilage was represented as uniform thickness solids that allowed prediction of compliant contact forces. As a final step, the subject specific model was validated by comparing predicted kinematics and triceps tendon forces to experimentally obtained data of the identically loaded cadaver elbow. The maximum root mean square (RMS) error between the predicted and measured kinematics during the complete testing cycle was 4.9 mm medial-lateral translational of the radius relative to the humerus (for Specimen 2 in this study) and 5.30 internal-external rotation of the radius relative to the humerus (for Specimen 3 in this study). The maximum RMS error for triceps tendon force was 7.6 N (for Specimen 3).

• 대한족부족관절학회지
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• 제25권4호
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• pp.165-170
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• 2021

Purpose: This study sought to evaluate the clinical effectiveness of the shortening effect of the modified Weil osteotomy for the treatment of Freiberg's disease. Materials and Methods: We reviewed 21 cases treated with the modified Weil osteotomy for Freiberg's disease from November 2005 to June 2019. The average follow-up period was 32.5 months and the mean age of the patients was 38.3 years. The clinical results were analyzed using the American Orthopaedic Foot and Ankle Society (AOFAS) lesser metatarsophalangeal-interphalangeal scale, the visual analogue scale (VAS), and the range of motion (ROM) of the metatarsophalangeal joint. In the radiologic evaluation, the length of preoperative and postoperative metatarsal shortening was compared. Results: The average AOFAS lesser metatarsophalangeal-interphalangeal scale showed an improvement from 60.5 preoperatively to 90.9 at the latest follow-up. VAS showed a decrease from 5.4 preoperatively to 0.9 at the latest follow-up. ROM of the affected metatarsophalangeal joint increased from 40.2 degrees preoperatively to 58.6 degrees at the latest follow-up. The mean length of metatarsal shortening was 6.7 mm. There was no transfer metatarsalgia, osteonecrosis, and definite joint space narrowing. Conclusion: Modified Weil osteotomy with second layer cutting is an effective treatment option to restore the joint surface and painless joint motion for patients with Freiberg's disease.

• 한국지반공학회논문집
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• 제18권4호
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• pp.229-238
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• 2002

본 연구에서는 절리면 거칠기를 정량적으로 산출하기 위하여 표면 거칠기 계수, Rs를 이용한 측정방법을 제안하고, 이를 바탕으로 절리면 거칠기가 절리면 전단강도에 미치는 영향을 제시하였다. 제시된 Rs를 이용하여 새로운 절리면 전단강도 모델을 제안하였다. 연구 결과, 표면 거칠기 계수인 Rs는 암반의 절리면 거칠기를 정량적으로 표현할 수 있는 유용한 방법이 될 수 있음을 알 수 있었다. Rs에 의한 암코아 규모의 절리면 거칠기 측정에는 최대 측정간격으로 2mm, 최소 측정 길이로 5cm가 적당하나, 이를 대규모의 현장 절리면에 확대 적용하기 위해서는 변동규모(scale of fluctuation), $\delta_u$를 도입하여야 한다. 절리면 거칠기가 작은 경우, 전단강도는 절리면에서의 미끄러짐으로 유발되었으나, 거친 절리면에서의 전단강도는 거칠기의 일부분이 파괴됨으로 인하여 발생됨을 알 수 있었다.

• 척추신경추나의학회지
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• 제2권2호
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• pp.151-160
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• 2007

Objectives : This study was carried out to investigate the effects of Chuna & General Oriental Method on Temporomandibular Joint Disorder Patient(Functional Lateral Mandibular Displacement) with Many Clinical Symptoms. Methods : The therapies were Chuna, acupuncture treatment and herbal medicine. We estimated the effects of treatment by measuring the length from the end of frenulum labii superioris to the frenulum labii inferioris, Visual Analog Scale(VAS) and Patient Global Assessment(PGA) before and after treatment. Results : After treatment, we confirmed these improvements: the length from the end of frenulum labii superioris to the frenulum labii inferioris changed from 10-7mm to 0-2mm, the VAS was changed from 10 to 0-2 and many clinial symptoms improved. Conclusions : These results suggusted that Chuna & General Oriental Method effected for Temporomandibular joint disorders caused many clinical symptoms.