• Journal of Aerospace System Engineering
• /
• v.9 no.4
• /
• pp.31-36
• /
• 2015

The fatigue analysis for cutout panel used for the weight reduction of aircraft has been conventionally performed through the open hole concept using the reference stress and stress concentration factor (Kt). However, in the actual structure cases, the goal of weight reduction might be less meaningful due to the conservative approach induced by the difficulties of extracting the confident reference stress from FE-Analysis in the complicated loading behavior. Therefore a new approach is proposed in order to secure the effectiveness of weight reduction and validate the confidence of the analysis results using the interaction of max-min principal stress at the critical location of open hole edge line.

• Journal of Korean Foot and Ankle Society
• /
• v.18 no.4
• /
• pp.222-226
• /
• 2014

Four patients with soft tissue defects around the ankle joint were covered with peroneal artery perforator-based propeller flaps. Using color Doppler sonography, the flap was designed by considering the location of the perforator and soft tissue defects. The procedure was then performed by rotating the flap by $180^{\circ}$. Additional skin graft was required in a patient due to partial necrosis, and delayed wound repair was performed in another patient with poor blood circulation at the distal part of the flap. The remaining patients did not have any complications and results were considered excellent. Good outcomes were eventually obtained for all patients.

• Korean Journal of Applied Biomechanics
• /
• v.23 no.2
• /
• pp.131-139
• /
• 2013

Naejirgi is one of the fastest, most forceful and most often being used kicks in Taekkyon games, The purpose of this study was to investigate kinetic factors on two types of Naejirgi kick, one of which uses knee bending of supporting leg and the other uses little it. 12 taekkyoners (11 males and one female) who are the students of Y University participated in this study. They have been practicing on Taekkyon for five years or more. Positions of CoM, the elapsed time of each phase, vertical ground reaction forces, joint moments and impulses of supporting leg were analyzed for this study. The results were as follows; in Naejirgi with knee bending of supporting leg than without knee bending of supporting leg, the vertical motion range of whole body CoM was larger during phase 2 and 3, the elapsed time of phase 4 were longer, players stayed longer in the nearest location to opponent, during phase 4 the vertical ground reaction forces of supporting foot were larger, and joint extension moments and angular impulses of supporting leg (especially knee) were larger. In conclusion supporting knee bending is not a useful strategy for Naejirgi, because players stay longer in the nearest position to opponent and consumed more muscle force and energy for producing the vertical momentum which is unnecessary for pushing down the opponent.

• Journal of Welding and Joining
• /
• v.23 no.5
• /
• pp.61-68
• /
• 2005

Dissimilar joining of Al 6013-T4 alloys and austenite stainless steel was carried out using friction stir welding technique. Microstructures near the weld zone and mechanical properties of the joint have been investigated. Microstructures in the stainless steel side were composed of the heat affected zone and the plastically deformed zone, while those in the Al alloy side were composed of the recrystallized zone including stainless steel particles, the thermo-mechanically affected zone and the heat affected zone. TEM micrographs revealed that the interface region was composed of the mixed layers of elongated stainless steel and ultra-fine grained Al alloy with lamella structure and intermetallic compound layer. Thickness of the intermetallic layer was approximately 300nm and was identified as the A14Fe with hexagonal close packed structure. Mechanical properties, such as tensile and fatigue strengths were lower than those of 6013 Al alloy base metal, because tool inserting location was deviated to Al alloy from the butt line, which resulted in the lack of the stirring.

• Smart Structures and Systems
• /
• v.24 no.3
• /
• pp.293-301
• /
• 2019

Bolted joints are commonly used in civil infrastructure and mechanical assembly structures. Monitoring and identifying the connection status of bolts is the frontier problem of structural research. The existing research is mainly on the looseness of a single bolt. This article presents a study of assessing the loosening/tightening health state and identifying the loose bolt by using ultrasonic guided wave in a bolt group joint. A bolt-tightening index was proposed for evaluating the looseness of a bolt connection based on correlation coefficient. The tightening/loosening state of the bolt was simulated by changing the bolt torque. More than 180 different measurement tests for total of six bolts were conducted. The results showed that with the bolt torque increases, value of the proposed bolt-tightening index increases. The proposed bolt-tightening index trend was very well reproduced by an analytical expression using a function of the torque applied with an overall percentage error lower than 5%. The developed damage index based on the proposed bolt-tightening index can also be applied to locate the loosest bolt in a bolt group joint. To verify the effectiveness of the proposed method, a bolt group joint experiment with different positions of bolt looseness was performed. Experimental results show that the proposed approach is effective to detect and locate bolt looseness and has a good prospect of finding applications in real-time structural monitoring.

• Physical Therapy Rehabilitation Science
• /
• v.10 no.2
• /
• pp.90-97
• /
• 2021

Objective: The purpose of this study was to find out how the back instability during clam exercise (CE) causes changes in pelvic rotation and hip joint abductor muscle activity, and to find out the effects with different methods of application of pressure biofeedback. Design: Comparative study using repeated measures. Methods: Each subjects performed the clam exercise (CE) without pressure biofeedback, the clam exercise with pressure biofeedback applied to the back (CE-PBU to back), and the clam exercise with pressure biofeedback applied to the side (CE-PBU to side). The amount of pelvic rotation was measured using myomotion. And the muscle activity of the muscle gluteus medius and the tensor fasciae latae was measured using EMG device. One-way repeated measures ANOVA followed by the Bonferroni post test were used to compare the EMG activity in each muscle and pelvic rotation angle during the CE, CE-PBU to back, CE-PBU to side. Results: The amounts of pelvic rotation was the lowest in CE-PBU to back (p< 0.05) and the ratio of muscle activity of the muscle gluteus / tensor fasciae latae was the highest in CE-PBU to back (p< 0.05). Conclusions: It is thought that, in order to stabilize the waist-pelvis and increase hip joint muscle strength in subjects with back instability, applying clam exercise with pressure biofeedback applied to the lower back is effective in improving waist-pelvic movements and selectively strengthening the muscle gluteus medius.

• Journal of Korean Physical Therapy Science
• /
• v.28 no.1
• /
• pp.23-32
• /
• 2021

Background: The purpose of this study was to find out how the lumbar instability during clam exercise causes changes in pelvic rotation and hip joint abductor muscle activity. Design: Case-control study. Methods: Twenty male participated in this study. The amount of pelvic rotation was measured using myomotion during the clam exercise in a normal group and a group of patients with low lumbar instability, and the muscle activity of the muscle gluteus medius and the tensor fasciae latae using an EMG device. Results: The amount of pelvic rotation that occurred during the clam exercise was statistically significantly greater in the lumbar instability group than in the normal group (p<.05), and the ratio of muscle activity of the muscle gluteus medius/the tensor fasciae latae was statistically significantly higher in the normal group than in the lumbar instability group (p<.05). Conclusion: In order to stabilize the lumbo-pelvic and strengthen the strength of the hip joints, it is believed that it is necessary to apply exercise while controlling the lumbo-pelvic movement during clam exercises, and various studies will be needed.

• Clinics in Shoulder and Elbow
• /
• v.26 no.2
• /
• pp.126-130
• /
• 2023

Background: Arm swing plays a role in gait by accommodating forward movement through trunk balance. This study evaluates the biomechanical characteristics of arm swing during gait. Methods: The study performed computational musculoskeletal modeling based on motion tracking in 15 participants without musculoskeletal or gait disorder. A three-dimensional (3D) motion tracking system using three Azure Kinect (Microsoft) modules was used to obtain information in the 3D location of shoulder and elbow joints. Computational modeling using AnyBody Modeling System was performed to calculate the joint moment and range of motion (ROM) during arm swing. Results: Mean ROM of the dominant elbow was 29.7°±10.2° and 14.2°±3.2° in flexion-extension and pronation-supination, respectively. Mean joint moment of the dominant elbow was 56.4±12.7 Nm, 25.6±5.2 Nm, and 19.8±4.6 Nm in flexion-extension, rotation, and abduction-adduction, respectively. Conclusions: The elbow bears the load created by gravity and muscle contracture in dynamic arm swing movement.

• The Korean Journal of Applied Statistics
• /
• v.33 no.2
• /
• pp.123-136
• /
• 2020

It is common to encounter correlated multiple outcomes measured on the same subject in various research fields. In developmental toxicity studies, presence of malformed pups and fetal weight are measured on the pregnant dams exposed to different levels of a toxic substance. Joint analysis of such two outcomes can result in more efficient inferences than separate models for each outcome. Most methods for joint modeling assume a normal distribution as random effects. However, in developmental toxicity studies, the response distributions may change irregularly in location and shape as the level of toxic substance changes, which may not be captured by a normal random effects model. Motivated by applications in developmental toxicity studies, we propose a Bayesian joint model for binary and continuous outcomes. In our model, we incorporate a skewed logit model for the binary outcome to allow the response distributions to have flexibly in both symmetric and asymmetric shapes on the toxic levels. We apply our proposed method to data from a developmental toxicity study of diethylhexyl phthalate.

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.3 no.1
• /
• pp.38-46
• /
• 2010

The lesions around hip joint including bone, joint and soft tissue can cause the pain. For diagnosis of these lesions, physical examination and simple X-ray were accomplished primarily. Some special cases, CT or MRI was a useful tool. However ultrasonography could provide non-invasive and dynamic images for the lesions of tendon and bursa, and it could be a useful tool for follow up after hip surgery. Due to the deep location of hip joint, ultrasonography is not easy for physician to examine and its application was impossible in some obese patients. This article deals with the normal and pathologic ultrasonographic findings of the hip joint and various applications using ultrasonography.