• 한국운동역학회지
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• 제17권2호
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• pp.157-166
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• 2007

This study was to compare the major kinematic factors between the success and failure group on performing the back somersault motion in floor exercise. Three gymnasts(height : $167.3{\pm}2.88cm$, age : $22.0{\pm}1.0years$, body weight : $64.4{\pm}2.3kg$) were participated in this study. The kinematic data was recorded at 60Hz with four digital video camera. Two successful motions and failure motions for each subject were selected for three dimensional analysis. 1. Success Trail It was appear that success trail was larger than failure group in projection velocity, but success trail was smaller than failure trail in projection angle. Also it was appear that success trail was longer than failure group in the time required. Hand segment velocity and maximum velocity in success trail were larger than those in failure trail, and this result was increasing the projection velocity and finally increasing the vertical height of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle was contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle was maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of success trail extended more than those of failure trail. in this base, success trail in upward phase(p3) 2. Failure Trail It was appear that failure trail was smaller than success trail in projection velocity, but failure trail was larger than success trail in projection angle. Also it was appear that failure trail was more short than success trail in the time required. Hand segment velocity and maximum velocity in failure trail were smaller than those in success trail, and this result was reducing the projection velocity and finally reducing the vertical high of center of mass. At the take-off(event 2), flection amount of hip and knee joint angle wasn't contributed to the optimal condition for the take-off and at the peak point, hip and knee joint angle wasn't maximum flexed for reducing the moment of inertia. Also in this point, upper extremities of failure trail didn't extended more than those of success trail.

• Archives of Plastic Surgery
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• 제36권2호
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• pp.221-224
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• 2009

Purpose: The treatment of children mandibular condyle fracture that is severely displaced is controversial. The conservative treatment of it may lead to complications - mandibular deficiency, asymmetry, malocclusion and temporomandibular joint dysfunction. Moreover, open reduction carries risks for growth retardation, facial nerve injury, scarring and joint stiffness. The aim of this article is to present an alternative technique of the treatment by using a threaded Kirschner wire and external rubber traction. Materials: From November 2005 to May 2008, three patients underwent the management by using a threaded Kirschner wire and external rubber traction. A threaded Kirschner wire was inserted in the condylar segment by using a C-arm. We applied the external rubber traction, and we reducted the segment progressively until complete reduction. The mandibular - maxillary fixations were removed after 3 weeks, and patients went into training for mouth opening. Results: The technique didn't result in complications - joint dysfunction, facial nerve injury, sore, infection and nonunion during follow - up period. Radiologic follow - up examinations revealed correct reduction in all patients. In all cases, we found restoration of preinjury occlusion and temporomandibular joint function. Conclusions: Closed reduction of children mandibular condyle fracture by using a threaded Kirschner wire and external rubber traction did achieve anatomic reduction and restore mandibular height. This alternative technique is simple, effective, inexpensive, easy to apply and minimally invasive.

• 한국운동역학회지
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• 제24권3호
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• pp.229-238
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• 2014

This study comparatively analyzed the speed and segment coordination characteristics of Taekwondo hand techniques, while different attention focusing strategies were utilized. Ten elite Taekwondo poomsae athletes participated, and three different strategies (no focus, target focus, body focus) were utilized in random order. The hand velocity and upper body segment coordination characteristics were analyzed, with the following results. First, the maximum magnitudes of the hand velocity differed between the focus conditions for the Araenaereomakgi and Momtongjireugi techniques. Second, the angular velocity and kinetic energy transfer patterns of the segments differed between the focus conditions, and in the case of the body focus condition, the movement was more correct according to the theory. Third, the shoulder and elbow joint coordination patterns differed between the focus conditions, with more efficient movement shown with the body focus condition. In conclusion, we confirmed the potential of effectively using an attention focusing strategy in a taekwondo teaching situation. However, the effect on the movement coordination and results of the movement could be changed by a difference in the cue provided or the type of the task. In addition, depending on the task, the attention focusing strategy could affect the efficiency of the movement. Therefore, coaches and masters of Taekwondo will have to constitute determine the appropriate attention focusing cues based on the task.

• 한국운동역학회지
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• 제16권3호
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• pp.85-94
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• 2006

The purpose of this study was to analyze the kinematics variables of during forehand stroke by stance patterns. Eight high school tennis players were chosen for the study, who have never been injured for last six months, in Busan. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, open and semi-open stance. It was filmed by 6 video camera and used with 3-dimensional motion analyzer system. The following kinematic variables were analyzed in relation to angle of segment( shoulder, hip and knee joint). The conclusion were as follow: 1. The angle of hip joint represented at impact that horizontal swing was not significant difference by stance patterns but vertical swing was increased in open stance than square and semi-open stance. 2. The angle of both knee was not significant difference between all stance types and swing patterns. 3. The angle of shoulder, hip and knee joint rotation showed that open stance was increased than square and semi-open stance in all swing types and event.

• Geomechanics and Engineering
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• 제30권4호
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• pp.383-392
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• 2022

Although pipelines are composed of segmental tubes commonly connected by rubber gasket or push-in joints, current studies mainly simplified pipelines as continuous structures. Effects of joints on three-dimensional deformation mechanisms of existing pipelines due to tunnel excavation are not fully understood. By conducting three-dimensional numerical analyses, effects of pipeline burial depth, tunnel burial depth, volume loss, pipeline stiffness and joint stiffness on bending strain and joint rotation of existing pipelines are explored. By increasing pipeline burial depth or decreasing tunnel cover depth, tunneling-induced pipeline deformations are substantially increased. As tunnel volume loss varies from 0.5% to 3%, the maximum bending strains and joint rotation angles of discontinuous pipelines increase by 1.08 and 9.20 times, respectively. By increasing flexural stiffness of pipe segment, a dramatic increase in the maximum joint rotation angles is observed in discontinuous pipelines. Thus, the safety of existing discontinuous pipelines due to tunnel excavation is controlled by joint rotation rather than bending strain. By increasing joint stiffness ratio from 0.0 (i.e., completely flexible joints) to 1.0 (i.e., continuous pipelines), tunneling-induced maximum pipeline settlements decrease by 22.8%-34.7%. If a jointed pipeline is simplified as a continuous structure, tunneling-induced settlement is thus underestimated, but bending strain is grossly overestimated. Thus, joints should be directly simulated in the analysis of tunnel-soil-pipeline interaction.

• 한국강구조학회 논문집
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• 제22권2호
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• pp.161-171
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• 2010

교량은 재료의 발달과 신형식의 개발로 많은 발전을 이루어 왔으나, 현장에서 거의 모든 작업 공정이 이루어진다는 기본 틀을 탈피하지 못하고 있다. 급속 시공 건설 기술은 현재 세계적으로 그 효용성이 증가하게 되어 현재 국내 외적으로 조립식 교량에 대한 연구가 활발하게 진행되고 있다. 하지만, 상부구조와 비교하여 하부구조의 경우에는 연구 및 시공 실적이 매우 미미한 실정이다. 본 연구에서는 조립식 내부 구속 중공 CFT 교각에 대해서 대략적으로 설명하고, 교각 세그먼트 접합부의 설계식을 제안하였으며 교각 세그먼트 접합부의 구성요소에 대한 매개변수 연구를 수행하였다.

• Geomechanics and Engineering
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• 제6권3호
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• pp.263-275
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• 2014

The development of transportation in large cities requires the construction of twin tunnels located at shallow depth. As far as twin tunnels excavated in parallel are concerned, most of the cases reported in literature focused on considering the effect of the ground condition, tunnel size, depth, surface loads, the relative position between two tunnels, and construction process on the structural lining forces. However, the effect of the segment joints was not taken into account. Numerical investigation performed in this study using the $FLAC^{3D}$ finite difference element program made it possible to include considerable influences of the segment joints and tunnel distance on the structural lining forces induced in twin tunnels. The structural lining forces induced in the first tunnel through various phases are considerably affected by the second tunnel construction process. Their values induced in a segmental lining are always lower than those obtained in a continuous lining. However, the influence of joint distribution in the second tunnel on the structural forces induced in the first tunnel is insignificant. The critical influence distance between two tunnels is about two tunnel diameters.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제38권
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• pp.24.1-24.7
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• 2016

Background: This study aimed to evaluate the structural changes of temporomandibular joint immediately after condylar fractures with magnetic resonance imaging (MRI). Method: We evaluated 34 subjects of condylar fractures with MRI. The position, shape, and signal intensity of the condyle, disc, and retrodiscal tissue were analyzed with MR images. Results: Immediately after trauma, the disc was displaced with the fractured segment in almost all cases. And, the changes of signal intensity at the retrodiscal tissue were found but less related to the degree of fracture displacement. And, the high signals were observed almost at all fractured joint spaces and even at some contralateral joints. Conclusions: The displaced disc as well as the increased signal intensity of the joint space, condylar head, and retrodiscal tissue demands more attention to prevent the possible sequela of joint.

• 항공우주시스템공학회지
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• 제3권2호
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• pp.12-19
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• 2009

The research for the fatigue analysis is regarded greatly as important in aerospace field. Moreover, a study on the fatigue characteristic is very actively progressing. In this study, the fatigue life estimation was performed for Flaperon Joint which has FCL(fatigue critical location) of tilt-rotor UAV. The Flaperon Joint should be taken the various loads by several missions profiles of UAV. The fatigue load spectrum of Flaperon Joint is generated by the standard mission segment for the tilt-rotor UAV, and this spectrum is used for the fatigue test and analysis. The in-house fatigue analysis program is applied to calculate the fatigue life based on Stress-Life(S-N) method. The S-N curve is generated from the S-N data of Mil-Handbook by second order polynomial regression method. Moreover, the coefficient of determination is used to ensure how accuracy it has. In addition, the Goodman equation is used to consider the mean stress effect for evaluating more accurate fatigue life. Finally, the result of fatigue analysis is verified by comparing with the fatigue test result for the Flaperon Joint.

• 한국운동역학회지
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• 제18권4호
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• pp.179-189
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• 2008

본 연구는 9명의 남자 중학교 초보피험자들을 대상으로 태권도 옆차기 동작의 숙련정도에 따른 운동학적 협응과정을 살펴보는 데 목적을 두었다. 이용된 변인은 최대합성직선속도, 분절간 각속도, 각도 대 각도 도면이었다. 분석결과, 연습후기로 갈수록 인접한 분절간의 운동량 전이가 잘 이루어져 각 분절의 최대합성직선속도가 유의하게 증가하였으며 분절간 각속도에서 학습후기로 갈수록 몸통에서 대퇴, 하퇴분절로의 순차적인 전이를 보였으며 던지는 듯하면서 미는 듯한 동작형태를 보였다. 엉덩관절과 무릎관절의 각도-각도 도면에서는 학습초기에는 다이나믹스한 변화를 보였으나 학습이 됨에 따라 숙련된 피험자처럼 안정적인 협응 패턴을 보여주었다.