• 한국운동역학회지
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• 제13권2호
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• pp.123-137
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• 2003

This study is to present more effective starting skills through analysis of kinematic characteristics of starting motions in 300m Time Trials of Inline Skating. To achieve this goal, 6 athletes, 3 in the national team and 3 in business teams were chosen and their starting motions were examined with three-dimensional image analyses. The results of analyses in regard of positions and speed of the bodily center and angles, angular velocity, and linear velocity of articulations of lower limbs by sections of starting motions are as follows: In case of the central position, though it is effective to reduce the air resistance by lowering the upper part of the body maximumly, it is reasonable to accelerate by raising the upper part of the body to some degree for the running posture at the lower speed in the starting section. In the starting section, it is efficient to minimize the period of time in touching the ground. for this, it is necessary to train for taking motions without slippage while touching the ground. While 3 athletes in business teams kicked the ground as running right after the starting, the others in the national team slid on the ground. As the number of steps increased, the movable speed changed quickly. Thus the movable speed of athletes in the national team indicated big differences in two to three steps. If these factors are well supported, the push-away starting method might be better than the running starting method in terms of improvement of records.

• 한국운동역학회지
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• 제31권4호
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• pp.283-289
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• 2021

Objective: The aim of this study was to analyze the pattern of Kolman technique by five Korean top gymnasts including the three national athletes on horizontal bar. Method: Two digital high-speed camcorders were used with 90 frames/sec and their Kolman motions were filmed in sports science secondary school gymnasium at U city. After the kinematic and kinetic variables were carried out by Kwon3D 3.1 motion package during the whole phase, the optimized release motion was investigated by simulating the body COG path during the aerial phase. Results: Firstly, it was revealed that the average changes of hip, shoulder joint angle were 84 deg, 53 deg respectively during the functional sub-phase and the average swing phaseal time was 1.21 s. Secondly, it was revealed that the average body COG positions and velocities (Y, Z) at release were -0.65 m, 0.48 m, 1.65 m/s, 3.97 m/s respectively and the average release angle, peak height and flight time were 67 deg, 1.29 m, 0.79 s respectively. Thirdly, it was revealed that the directions of somersault of whole and lower body, tilt of lower body were counterclockwise, whereas the directions of tilt of whole body, twist of whole and lower body were clockwise at the ready for re-grasp. Lastly, it was revealed that the body COG paths were different from each other during the aerial phase followed by the different body COG velocities. Conclusion: Korean gymnasts of this study controlled their motions well in terms of the timing of hip·shoulder joint, body position, body angular momentum especially during the functional sub-phase, but their motions were different during the aerial phase. Nonetheless most of them made the adequate body position at the instant of re-grasp. It would be suggested that Korean gymnasts except S3 should increase the vertical velocity.

• 한국운동역학회지
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• 제31권3호
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• pp.183-188
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• 2021

Objective: The purpose of this study was to develop a stretchable joint motion sensor that is based on silver nano-particle. Through this sensor, it can be utilized as an equipment for rehabilitation and analyze joint movement. Method: In this study, precursor solution was created, after that, nozel printer (Musashi, Image master 350PC) was used to print on a circuit board. Sourcemeter (Keithley, Keithley-2450) was used in order to evaluate changes of electric resistance as the sensor stretches. In addition, the sensor was attached on center of a knee joint to 2 male adults, and performed knee flexion-extension in order to evaluate accurate analysis; 3 infrared cameras (100 Hz, Motion Master 100, Visol Inc., Korea) were also used to analyze three dimensional movement. Descriptive statistics were suggested for comparing each accuracy of measurement variables of joint motions with the sensor and 3D motions. Results: The change of electric resistance of the sensor indicated multiple of 30 times from initial value in 50% of elongation and the value of electric resistance were distinctively classified by following 10%, 20%, 30%, 40% of elongation respectively. Through using the sensor and 3D camera to analyze movement variable, it showed a resistance of 99% in a knee joint extension, whereas, it indicated about 80% in flexion phase. Conclusion: In this research, the stretchable joint motion sensor was created based on silver nanoparticle that has high conductivity. If the sensor stretches, the distance between nanoparticles recede which lead gradual disconnection of an electric circuit and to have increment of electric resistance. Through evaluating angle of knee joints with observation of sensor's electric resistance, it showed similar a result and propensity from 3D motion analysis. However, unstable electric resistance of the stretchable sensor was observed when it stretches to maximum length, or went through numerous joint movements. Therefore, the sensor need complement that requires stability when it comes to measuring motions in any condition.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.379-385
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• 2018

Purpose: Postharvest handling of onions (harvesting, cleaning, grading, cooling, storing, and transport) should be performed continually to reduce costs and improve quality. The purpose of this study is to a) determine the design parameters and operating conditions of anion auto-dumping that constitutes a key component of the postharvest bulk handling machinery system, and b) to perform a performance test with the auto-dump prototype system. Methods: Kinematic analyses and computer simulations of the auto-dump mechanism were applied to analyze the operating conditions and design parameters. Results: The optimum working condition for the auto-dump was determined from kinetic analyses. In addition, the interaction between the velocity of the hydraulic cylinder and the angular velocity of the auto-dump were analyzed in order to control the bulk handling machinery system. The acting forces and optimum operating conditions of the hydraulic cylinder were determined by analyzing the forces related to the mass of inertia of the auto-dump assembly during rotation. The method of controlling the feeding rate of onions in terms of the uniformity of the stacking pattern and the control of the entire system was better than the two-stage method of controlling the rotational speed of the auto-dump. Based on the performance test with the prototype for the auto-dump, the stacking pattern and rigidity of the system were analyzed. Conclusions: These results would be of great importance in the postharvest bulk handling machinery system for onions.

• 한국운동역학회지
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• 제29권3호
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• pp.129-135
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• 2019

Objective: The purpose of this study is to present the scientific and quantitative data by finding the common points and differences of the side-kick according to the height change through the difference of the side kick motion performance according to the three target height changes and the function of the lower limbs muscle in side kick motion of Taekwondo Poomsae. Method: For this, total 14 players were selected who were registered in Korea Taekwondo Association and skilled group 7 players who had a medal from national competition and 7 players who did not have Taekwondo experience from department of physics. 4 video cameras to the feature on side kick per target height, and the subjects' support foot was located on the ground reactor and the practice was conducted 3 times: waist, chest, and head as the target height. the basic materials were collected by using Kwon 3D XP program and the T-test was conducted to verify the statistic difference between groups (SPSS 24.0). At this time, the statistics significance level was set as .05 and the following conclusion was obtained. Results: The lower the proficiency and the higher the height, the more the joint coordination between the hip and the knee. Conclusion: Summary of the result shows a common point that the change of target's height makes the lower the proficiency and the higher the height, the more the joint coordination between the hip and the knee. Also, the higher the target's height became, the greater angular momentum of thighs, shanks, foot became in common.

• 한국전문물리치료학회지
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• 제13권2호
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• pp.16-25
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• 2006

The aim of this study was to investigate the kinematics of young adults during descent ramp climbing at different inclinations. Twenty-three subjects descended four steps at four different inclinations (level, $-8^{\circ}$, $-16^{\circ}$, $-24^{\circ}$). The 3-D kinematics were measured by a camera-based Falcon System. The data were analyzed using one-way ANOVA and the Student-Newman-Keuls test. The kinematics of descent ramp walking could be clearly distinguished from the kinematics of level walking. On a sagittal plane, the ankle joint was more plantar flexed at initial contact with $-16^{\circ}/-24^{\circ}$ inclination, was decreased in the toe off position with all inclinations (p<.001),and was decreased at maximum plantar flexion during the swing phase (p<.001). The knee joint was more flexed at initial contact with the $-24^{\circ}$ inclination (p<.001), was more flexed in the toe off position with all inclinations (p<.001), and was more flexed at minimum flexion during stance phase and at maximum flexion during swing phase with $-16^{\circ}$, $-24^{\circ}$ inclination (p<.001). The hip joint was more flexed in the toe off position with $-16^{\circ}$, $-24^{\circ}$ inclination and was deceased at maximum extension during stance phase with $-16^{\circ}$, $-24^{\circ}$ inclination (p<.05). In the frontal plane, the ankle joint was more everted at maximum eversion during stance phase with $-16^{\circ}/-24^{\circ}$ inclination (p<.01) and was decreased at maximum inversion during swing phase with $-16^{\circ}$, $-24^{\circ}$ inclination (p<.01). The knee joint was more increased at maximum varus during stance phase with $-16^{\circ}/-24^{\circ}$ inclination (p<.001). The hip joint was deceased at maximum adduction during stance phase with $-24^{\circ}$ inclination (p<.05). In a horizontal plane, only the knee joint was increased at maximum internal rotation during stance phase with $-24^{\circ}$ inclination (p<.05). In descent ramp walking, the different gait patterns occurred at an inclination of over $16^{\circ}$ on the descending ramp in the sagittal and frontal planes. These results suggest that there is a certain inclination angle or angular range where subjects do switch between level walking and descent ramp walking gait patterns.

• 대한기계학회논문집 C: 기술과 교육
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• 제1권2호
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• pp.153-165
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• 2013

기존의 보행분석 연구들은 하지를 하나의 스프링으로 간주하였다. 만약 슬관절 신전을 보조할 수 있는 슬관절 액추에이팅 메커니즘을 개발할 수 있다면 보행에 필요한 탄성-변형률에너지를 혁신적으로 저장-방출할 수 있고, 그 결과 보행 중 하지강성은 더욱 증가할 것이다. 게다가 족관절 액추에이팅 메커니즘까지 추가되어 있다면 슬관절 액추에이터에 의한 과도한 인공하지강성을 능동적이고 적절한 수준으로 보상해주는 기전으로 작동할 것이다. 만약 가속도에 의한 보행속도 증가를 방지하기 위해 인위적 감속통제를 작동시킨다면 불필요한 운동에너지의 방출이 발생되고 하지강성 액추에이터의 실효성은 의심을 받게 된다. 따라서 본 저자는 보행속도를 2개의 세그먼트에 의한 상대 각속도 조절기법을 이용하여 하지강성을 증가시킨다는 기본개념으로 슬-족관절 액추에이터 시스템을 개발하였다. 또한 족관절에 슬관절 액추에이팅에 대한 보상기전이 존재하는 경우, 족관절의 보상기전이 중족지절관절 경사각 및 보행속도 변화에 미치는 상호영향을 연구하였다.

• 한국운동역학회지
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• 제19권3호
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• pp.467-479
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• 2009

제주마를 이용한 경속보(rising trot)시 숙련정도에 따라 2보폭동안 기승자세를 비교 분석하여 교육과정에 응용 할 수 있는 정량적 자료를 제시한다. 참여한 피험자는 총 10명(숙련군: 5명, 미숙련군: 5명)이었고, 실험 및 분석 방법은 3차원 영상분석(Kwon3D Motion Analysis System)을 하였고, 분석변인은 국면 및 이벤트별 시간, 선 및 각운동변인이었다. 숙련군이 미숙련군에 비해 상대적으로 지지기보다 공중국면의 소요시간 비율이 더 많았고, 국면경과에 따라 더 적은 상하운동범위 속에서, 전후 및 좌우속도에서 더 일관된 속도를 유지하였고, 상하방향에서 말의 보조와 동조를 이루면서 일관된 주기를 이루면서 반동운동이 이루어졌다. 숙련군이 미숙련군에 비해 상대적으로 팔꿈치에서 더 많은 굴곡 및 국면경과에 따라 어깨의 더 많은 후방신전자세를 취하였다. 고관절과 무릎은 더 많은 전방굴곡자세를 취한 반면 발목의 경우 모두 저측굴곡의 자세를 유지하였다. 동체는 수직축에 대해 후방신전자세인 반면 미숙련군은 전방굴곡자세를 유지하였다. 즉 미숙련군의 경우 숙련군에 비해 다소 경속보에서 보조의 경과에 따라 불안한 자세를 취한 것으로 사료된다.

• 한국운동역학회지
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• 제19권1호
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• pp.77-85
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• 2009

본 연구는 배드민턴 드라이브 동작의 원리와 현상을 이해함은 물론 운동 시 정확한 동작을 유도하여 상해예방 및 기술향상을 기할 수 있도록 기초자료를 제공하고자 하였다. 라헤드의 이동변위는 모든 연구대상자들에게서 비슷한 패턴으로 나타났지만 다소 차이가 나타난 이유로는 신장, 상완과 전완의 길이, 스윙괘적의 개인적인 성향의 등 외부적인 요인에 의한 결과로 사료된다. 국면별 상지관절의 각도를 살펴보면 어깨 관절, 팔꿈치 관절, 손목 관절의 각도는 드라이브 동작을 수행함에 있어 서로 유기적인 관계로 얽혀 있으며 근위에서 원위로 힘의 전달을 한다는 분절 순서이론도 뒷받침하고 있다. 상지관절의 각속도는 연구대상자 모두에서 임팩트 이후 팔로우스루 동작에서도 크게 나타났는데 이는 배드민턴과 같은 라운동에서 팔로우스루의 중요도를 나타내는 것을 의미한다. 이 팔로우스루 동작은 자세의 안정성 유지, 동작의 자세교정, 관절의 상해예방이라는 측면에서 라운동 시 중요요소로 작용하고 있음을 보여주고 있다. 종합해보면 분절의 순서이론에 따른 스윙이 이루어져야 효율적인 동작을 할 수가 있을 것으로 판단된다.

• 한국응용과학기술학회지
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• 제38권2호
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• pp.532-542
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• 2021

본 연구의 목적은 골프 스윙 시 3가지 스탠스에서 클럽헤드 스피드와 볼의 정확성을 유지하기 위한 신체 전략을 하지의 운동학적 변인과 지면반력 변인을 통하여 알아보고자 하였다. 연구의 대상은 공식 핸디캡이 2인 남자골프선수 10명으로 하였다. 모든 대상자들은 스탠스 조건(스퀘어, 오픈, 클로즈드)에 따라 어드레스 자세를 유지한 후 스윙을 수행하였다. 3차원 동작분석 시스템과 지면반력기를 이용하여 각 스탠스에 따라 7번 아이언 풀스윙을 수행한 결과를 산출하였다. 연구결과로 신체중심의 변위, 고관절 각변위, 무릎관절 각변위는 차이가 나타나지 않았다. 발목관절 각변위는 어드레스부터 다운스윙까지 왼쪽에서 오픈 스탠스가 저측굴곡이 크게 수행되었고, 오른쪽에서 클로즈드 스탠스에서 저측굴곡이 크게 수행되었다. 지면반력에서 전후, 수직은 차이가 없었지만, 어드레스부터 테이크백까지 왼발은 오른쪽 방향, 오른발은 왼쪽 방향의 힘이 오픈이 클로즈드 스탠스보다 크게 나타났다. 결론적으로 다양한 스탠스에도 불구하고, 임팩트 시 동일한 자세를 유지하는 것이 클럽헤드 스피드와 볼의 방향에 긍정적으로 작용되는 것으로 판단된다.