• 한국운동역학회지
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• 제18권4호
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• pp.67-76
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• 2008

본 연구는 인터스키 부정지 숏턴 동작에서 우수 집단과 비우수 집단 간 운동학적 변인의 차이를 3차원 영상 분석을 통해 보다 효과적인 부정지 숏턴 동작을 모색하고자 하였다. 연구 대상은 2007년 전국스키기술선수권대회 부정지 숏턴 경기에 참가한 선수 10명을 대상으로 DLT 방법을 이용한 3차원 영상분석을 통해 운동학적 변인을 분석하였으며, 그 결과 다음과 같은 결론을 얻었다. 총 소요시간 및 국면별 소요시간은 우수 집단이 비우수 집단보다 짧게 나타났다. 신체중심은 우수 집단이 비우수 집단보다 작은 좌우이동 폭과 큰 상하이동 폭을 나타내며, 직진성을 강화하는 활주를 하였으며, 그로 인하여 좌우속도를 제어하면서 빠른 전후속도를 나타냈다. 상하속도는 드롭 인 구간에서는 느리게 하면서 범프 업 구간에서 속도를 증가시킨 것으로 나타났다. 고관절각과 슬관절각은 우수 집단이 비우수집단보다 전체 이벤트에서 모두 작게 나타났으며, 동체 전경갈 신체 기울기각은 우수 집단이 비우수 집단보다 모두 크게 나타났다. 하퇴 전경각은 우수 집단이 비우수 집단보다 모글 중앙에서 크게 나타났으며, 동체 비틀기각은 우수 집단이 비우수 집단보다 드롭 인 구간에서 오른쪽 턴 방향으로, 범프 업 구간에서 왼쪽 턴 방향으로 크게 나타났다.

• 한국운동역학회지
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• 제27권2호
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• pp.99-108
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• 2017

Objective: The purpose of this study was to analyze the effects of skill level and width between feet on kinematic and kinetic variables during jump rope single under with both feet. Method: Fifteen subjects in the skilled group (age: $10.85{\pm}0.40yrs$, height: $142.13{\pm}5.41cm$, weight: $36.97{\pm}6.65kg$) and 15 subjects in the unskilled group (age: $10.85{\pm}0.40yrs$, height: $143.31{\pm}5.54cm$, weight: $40.81{\pm}10.39kg$) participated in this study. Results: Participants in the skilled group minimized the anteroposterior displacement of their center of mass by modifying the width between their feet and decreased the range of motion (ROM) of their trunk in the sagittal plane. The preferred width during the jump rope decreased by 5.61~6.11 cm (32~37%) in comparison to width during static standing. The induced width was increased by 16.44~16.67 cm (82~85%), regardless of skill level. The kinematic variables of the left and right legs of members of the unskilled group were significantly different from those of members in the skilled group regarding the ROM of the hip, knee, and ankle joint. Otherwise, the members of the skilled group were consistent in terms of the kinematic variables of the right and left legs. Conclusion: The preferred width between feet during the jump rope was found to be beneficial for maintaining dynamic stability. The unskilled group exhibited asymmetry in left and right motion within the ranges of motion of the ankle, knee, and hip joints, regardless of the width. Therefore, long-term accurate jump rope motions will contribute to an improvement in the left and right imbalances of the entire body.

• 한국운동역학회지
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• 제19권1호
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• pp.167-177
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• 2009

본 연구의 목적은 골프화 개발에 있어 골프화 종류에 따른 기능성 검증을 위해 골프 스윙 시 골프화 종류별 3차원 동작분석을 통하여 골프화가 골프 스윙에 미치는 영향을 알아보고자 한다. 연구대상은 골프 프로 자격증을 소지한 경력 10년 이상인 프로골퍼 5명으로 착용 골프화 사이즈가 270mm이었다. 스윙 동작 분석을 위해 Motion Analysis사(Santa Rosa CL USA)의 3차원 동작분석 시스템 및 EVaRT 4.2 소프트웨어를 사용하여 변인 값들을 분석하였다. 드라이버 스윙동작 중 어드레스(El), 탑(E2), 임팩트(E3), 피니쉬(E4)시의 각 이벤트 간의 구간(P1, P2, P3) 변인 값을 분석하여 스윙 구간별 시간, 최대속도, 신체이동 속도, 양발 분절의 속도, 발목의 뒤틀림 각도에 대한 조사를 실시하여 골프화의 종류와 수행능력의 연관성에 대하여 알아보았다. 실험결과 골프화 Type C의 경우 어드레스에서 탑까지의 시간이 가장 짧게 나타나 어드레스 시 안정성을 향상시켜 줄 것으로 사료된다. 또한 좌우 골프화의 최대 속도 신체중심 이동 최대 속도 좌우 발의 최대 속도의 경우도 골프화 Type C의 속도가 가장 빠르게 나타났으며 신체의 중심을 빠르게 하고 발의 회전력을 증가시켜 임팩트 시 다른 골프화보다 큰 힘을 전달할 수 있을 것으로 사료된다.

• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.125-131
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• 1999

For linkage mechanisms driven by a cam, cam profile is the major design factor and is determined by the cam follower motion. If a cam mechanism has additional kinematic linkage besides cam and follower then the follower motion should be specified from the motion of end linkage member so that cam would be able to generate the desired end linkage motion. In this paper, a cam-linkage mechanism is constructed with the combinations of modular linkage elements including cam and follower and as a result, a planar cam-linkage mechanism design software with the cam profile optimization function is developed and presented.

• 한국정밀공학회지
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• 제15권12호
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• pp.37-47
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• 1998

This study discusses the feed dog feeding mechanism of an industrial lock stitch sewing machine, which is a good example to study a machine kinematics. The feed dog feeding mechanism makes the fabrics directly be fed by an elliptic motion of the feed dog that is moved by a rotation of the top shaft and controlled by the feeding control mechanism. This study makes mathematical expressions of machine's motion in the feed dog feeding mechanism. Thus, the motions of this mechanism are characterized, namely how an elliptic motion of the feed dog is affected by the feeding control mechanism. Therefore, the above mathematical expressions may be a basis for the new design of the feed dog feeding mechanism and may be adapted to analysis. Development of the similar feed dog feeding mechanism can be applied to other type sewing machine.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.550-559
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• 2004

In this paper, a recursive formulation for generating the equations of motion of spatial mechanical systems is presented. The rigid bodies are replaced by a dynamically equivalent constrained system of particles which avoids introducing any rotational coordinates. For the open-chain system, the equations of motion are generated recursively along the serial chains using the concepts of linear and angular momenta Closed-chain systems are transformed to open-chain systems by cutting suitable kinematic joints and introducing cut-joint constraints. The formulation is used to carry out the dynamic analysis of multi-link five-point suspension. The results of the simulation demonstrate the generality and simplicity of the proposed dynamic formulation.

• 대한물리치료과학회지
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• 제2권1호
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• pp.383-392
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• 1995

The purpose of this investigation was to determine the intratester reliability of measurements obtained with 3 Dimensional Motion Analysis System(3DMAS) by tester on normal subject. Twenty subjects between the ages of 9 and 29(x=22) were evaluated with 3DMAS using a test-retest reliability procedure after a familiarization session. Computerized 3DMAS was done with 4 50 - Hz CCD cameras connected to the ELITE system(B. T. S., Italy) and kinetic data were collected from the AMTI force platform(AMTI., U. S. A). Data were analyzed by the Eliclinic software to obtain gait parameters, joint angles and joint internal moment and power. Test-retest revealed intraclass correlation coefficients from .80 to .99. A series of paired t-tests revealed no significant differences between test and retest values. Finally, it was concluded that tester with 3DMAS could obtain reliable measurements with 3DMAS for determining kinetic, kinematic and gait parameters in normal subjects.

• 한국운동역학회지
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• 제14권2호
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• pp.1-14
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• 2004

This study was intended to contribute to allowing athletes to raise a technical understanding of two motions of high difficulty such as the Swallow motion and the Nakayama motion and enhance their competitive power by analysing the kinematical factors required to link those two motions on the competitive scene on the rings for current national athletes. For this purpose, the game of the ring event was videotaped for male heavy gymnasts participating in the final elimination match of the 2004 Athens Olympic Games. This study attempted to select the performing motions of the final 1st-and 2nd-place athletes performing the linking motions from the Swallow motion and the Nakayama motion using the DLT(direct linear transformation) method. As a result, it arrived at the following conclusion : A1 properly performed the flexing and extending movements using the angular velocity of the segment and joint as the switching motion using the body at the time of linking the motion from the Swallow skill to the Nakayama skill. A2 was evaluated to perform the skill taking the form of depending on the force at the static state. Therefore, it is thought that A1 should take care of shaking at the time of using the elasticity of the body. It is thought that in case of A2 the proper use of the elasticity of the body take care of shaking at the switching motion while taking advantage of the force will contribute to his competitive power.

• 한국운동역학회지
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• 제21권1호
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• pp.85-95
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• 2011

Three-dimensional(3D) motion analysis is a useful tool for analyzing sports performance. During the last few decades, advances in motion analysis equipment have enabled us to perform more and more complicated biomechanical analyses. Nevertheless, considering the complexity of biomechanical models and the amount of data recorded from the motion analysis system, subsequent processing of these data is required for event-specific motion analysis. The purpose of this study was to develop a basic golf swing analysis algorithm using a state-of-the-art VICON motion analysis system. The algorithm was developed to facilitate golf swing analysis, with special emphasis on 3D motion analysis and high-speed motion capture, which are not easily available from typical video camera systems. Furthermore, the developed algorithm generates golf swing-specific kinematic and kinetic variables that can easily be used by golfers and coaches who do not have advanced biomechanical knowledge. We provide a basic algorithm to convert massive and complicated VICON data to common golf swing-related variables. Future development is necessary for more practical and efficient golf swing analysis.

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1185-1191
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• 2011

The kinematic characteristics of cutting device significantly affects cutting performance in 2-dimensional elliptical vibration cutting(EVC) where the cutting tool cuts workpiece, traversing a micro-scale elliptical trajectory in a trochoidal motion. In this study, kinematical characteristics of EVC device constructed with two parallel stacked piezoelectric actuators were analytically modeled and compared with the experimental results. The EVC device was subjected to step and low-frequency(0.1 Hz) sinusoidal inputs to reveal only its kinematical displacement characteristics. Hysteresis in the motion of the device was observed in the thrust direction and distinctive skew of the major axis of the elliptical trajectory of the cutting tool was also noticed. Discrepancy in the voltage-to-displacement characteristics of the piezoelectric actuators was found to largely contribute to the skew of the major axis of the elliptical trajectory of the cutting tool. Analytical kinematical model predicted the cutting direction displacement within 10 % error in magnitude with no phase error, but in estimating the thrust direction displacement, it showed a $27^{\circ}$ of phase-lag compared with the measured displacement with no magnitude error.