• 한국운동역학회지
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• 제17권1호
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• pp.91-97
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• 2007

The purpose of this study was to investigate the changes of various balls velocity under the different surface conditions after impact. For this study, four different balls were used which are golf ball, tang-tang ball, table tennis ball, and iron ball. And two different types of ground conditions were used which are artificial grass green and glass green. Movements of putter head and ball were recorded with 2 HD video cameras(60 Hz, 1/500s shutter speed). Small size control object($18.5cm{\times}18.5cm{\times}78.5cm$) was used in this study. To transfer the same amount of kinetic energy to the ball, pendulum putting machine was used. Analyzing the process of impact and the ball movement, a putter was digitized the whole movement but the ball was digizited within the 50cm movement. Velocities were calculated by the first central difference method(Hamill & Knutzen, 1995). Putter head velocities were about 112.2cm/s-116.2cm/s at impact. Maximum ball velocities were appeared 0.08s-0.10s after impact no matter what the ground conditions are. Table tennis ball recorded higher ball velocities than the other ball velocities and iron ball recorded the lowest ball velocity in this group. But Table tennis ball was influenced with the frictional force and immediately was decreased at the artificial grass green condition. If an object is received the kinetic energy under the static condition(v=0cm/s), the object recorded the maximum velocity shortly after the impact and then decreased the velocity because of the frictional force. The ball distance from the start position to the peak velocity position is about 6cm-10cm under the 112.2cm/s-116.2cm/s putting velocity with putter. 0.25 seconds later after impact balls were placed 40cm distance from the original position except iron ball. In this study, ball moving distances were too short therefore it was not possible to investigate the reactions after the translational force is disappeared. Rotational force would play a major role at the end of the ball movement. Future study must accept two things. One is long distance movement of ball and the other is balanced ground. Three-piece ball is a good item to investigate the golf ball movement on the different surface conditions.

• 한국운동역학회지
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• 제17권4호
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• pp.83-88
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• 2007

The purpose of this study was to investigate the ball velocity changes depending on the different linear momentum of putter head. For this study, two different moving conditions(25cm free fall and 35cm free fall) of putter head were set. And two different types of ground conditions were used which are artificial grass green($180cm{\times}600cm{\times}1cm$) and glass green($40cm{\times}130cm{\times}1cm$). Movements of putter head and ball were recorded with 2 HD video cameras(60 Hz, 1/500s shutter speed). Small size control object($18.5cm{\times}18.5cm{\times}78.5cm$) was used in this study. Ball and putter head velocities were calculated by the First Central Difference Method(Hamill & Knutzen, 1995). Linear momentum of ball and putter head were calculated with mass and its velocities. Before impact, the velocity of the putter head of 35cm free fall was about 30% greater than that of the putter head of 25cm free fall. Linear momentum of putter head of 35cm free fall was about 0.355-0.364kg m/s and 25cm free fall was 0.251 kg m/s. After impact, putter head lost its linear momentum about 14-19% and adjusting time of putter head after impact would be 0.1 second. After 0.1 second, putter moved the route same as before impact. Maximum ball velocities were appeared 0.08s-0.10s after impact no matter what the ground conditions are. Ball velocities struck by 35cm free fall were 30 % faster than 25cm free fall. Linear momentum of ball struck by putter head was greater than that of expected amount because the moving ball has translational energy and rotational energy. Future study must treat three things. One is ball must struck by the different putters with different materials. Another is two-piece ball and three-piece ball should be used for the same condition studies. The other is height of center of rotation of club should be changed. In this study, the height of center of rotation of club head is 71cm from the ground. But recently many golfers used the long putter. Therefore next study should apply the different height of center of rotation of club head.

• 한국정밀공학회지
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• 제30권9호
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• pp.961-968
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• 2013

In this paper, we propose an optimal design for starfish capturing manipulator module with four-bar linkage mechanism. A tool link with compliance is attached on the four-bar linkage, and the tool repeats detaching starfish from the ground and putting it into the storage box. Since the tool is not rigid and the manipulator is operating underwater, the trajectory of the tool tip is determined by its dynamics as well as kinematics. We analyzed the trajectory of the manipulator tool tip by quasi-static analysis considering both kinematics and dynamics. In optimization, the lengths of each link and the tool stiffness are considered as control variables. To maximize the capturing ability, capturing stroke of the four-bar manipulator trajectory is maximized. Reaction force and reaction moment, and other kinematic constraints were considered as inequality constraints.

• 한국운동역학회지
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• 제13권2호
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• pp.175-183
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• 2003

The purpose of this study was to analyze the kinetic energy of putter head and ball movements during the process of impact. Highly skilled 5 golfers(less than 1 handicap) participated in this study and the target distance was 3 m. Movements of ball and putter head were recorded with 2 VHS video cameras(60 Hz, 1/500 s shutter speed). Small control object($18.5{\times}18.5{\times}78.5\;cm$) was used in this sdtuldy. Analyzing the process of impact, putter was digitized before 0.0835 s and after 0.0835 s of impact. Ball was digitized 0.1336 s after impact. The results showed that the maximum speed was appeared at Impact and prolonged for a while. Contact point of the club head was within 0.7 cm to the z axis. After contacting the club head, the ball was moved above the ground level(slide) and returned to the ground with sliding and rolling. After contacting the ground, the speed of ball was relied on the surface of the ground. During impact, 70% of kinetic energy of club head has been transferred to the ball.

• 재활치료과학
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• 제9권2호
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• pp.99-117
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• 2020

목적 : 지역사회에서 생활하는 뇌졸중 장애인을 대상으로 작업기반 지역사회 재활이 뇌졸중 장애인의 작업수행기술에 미치는 영향을 연구하고, 작업 수행의 질과 만족도 변화에 대해 알아보고자 하였다. 연구방법 : 단일대상연구(Single subject research) 중 ABA 설계를 사용하였고, 뇌졸중 진단을 받은 심한 장애인 1명을 선정하였다. 연구 과정은 2019년 5월 21일부터 2019년 9월 7일까지 17주간 총 25회기(기초선 A 5회기, 중재 기간 B 14회기, 기초선 기간 A' 5회기, 추적 기간 1회기)로 진행하였다. 중재는 연구자가 대상자의 집으로 방문하여 진행되었다. 작업치료중재과정모델에 따라 중재 모델 선정 및 적용하였으며, 중재에는 과제 제공 및 피드백, 관련 정보 교육, 가정환경 수정, 지역자원 연계가 포함되었다. 작업기반 지역사회 재활 프로그램을 적용한 이후 일상생활에서 작업수행기술의 빈도 변화, 작업수행 만족도, 일상생활활동과 삶의 질의 변화를 알아보았으며, 추적 관찰하였다. 결과는 선형그래프와 막대그래프를 이용하여 시각적으로 분석하였다. 결과 : 작업기반 지역사회 재활 프로그램을 적용했을 때, 손 닿는 곳의 상의 입기, 침대에서 양말과 실내화 신기, 의자에 앉아 신발 신기 기술과 일상생활활동이 향상되었다. 작업수행기술 평가 결과 대상자의 작업수행 기술의 질이 향상되었음을 확인하였으며, 작업수행 만족도 또한 향상되었다. 결론 : 본 연구를 통해 작업기반 지역사회 재활 프로그램이 지역사회에 거주하는 뇌졸중 장애인의 작업수행기술을 향상할 수 있으며, 일상생활활동과 삶의 질, 작업수행 만족도에 긍정적인 영향을 미쳤다. 마지막으로 뇌졸중 대상자 뿐만 아니라 지역사회에 거주하는 장애 유형별로 작업기반 지역사회 재활 프로그램이 보편화 되기를 기대해 본다.

• 한국시뮬레이션학회논문지
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• 제24권4호
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• pp.35-41
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• 2015

자동포용 주퇴복좌장치는 사격충격을 흡수하기 위한 목적으로 개발된 장치이다. 만약 자동포에서 탄자가 발사 될 때 발생하는 매우 높은 수준의 사격충격을 흡수하지 못한다면 반동에 의하여 정밀한 타격은 불가능해진다. 본 연구에서는 이러한 역할을 하는 주퇴복좌장치의 해석모델을 멀티도메인 소프트웨어를 활용하여 개발하고 검증하는 것을 다룬다. 연구의 진행과정은 다음과 같다. 우선 설계의도를 파악하여 해석모델을 개발하고 기본적인 감쇠특성을 확인한다. 그리고 필드테스트에서 얻은 사격충격력을 해석모델에 부여하여 필드테스트와 동일한 환경을 해석도구 상에 구축한다. 최종적으로 주퇴복좌장치의 내부압력과 포신의 변위를 필드테스트 결과와 비교하여 멀티도메인 소프트웨어를 활용한 주퇴복좌장치의 해석모델이 유효성을 갖는지를 검증한다.