• 한국운동역학회지
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• 제26권1호
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• pp.71-82
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• 2016

Objective: The purpose of this study was to investigate kinematic comparisons of Tsukahara vault in gymnastics between a top-level athlete and sublevel collegiate athletes in order to obtain information on key biomechanical points for successful Tsukahara vaults. Methods: An Olympic gold medalist (height, 160 cm; weight, 52 kg; age, 25 years) and five sublevel collegiate gymnasts (height, $168.2{\pm}3.4cm$; weight, $59.6{\pm}3.1kg$; age, $23.2{\pm}1.6years$) participated in this study. They repeatedly performed Tsukahara vaults including one somersault. Fourteen motion-capturing cameras were used to collect the trajectories of 26 body markers during Tsukahara vaults. Event time, displacement and velocity of the center of mass, joint angles, the distance between the two hands on the horse, and averaged horizontal and vertical impact forces were calculated and compared. Results: The top-level athlete showed a larger range of motion (ROM) of the hip and knee joints compared to sublevel collegiate athletes during board contact. During horse contact, the top-level athlete had a narrow distance between the two hands with extended elbows and shoulders in order to produce a strong blocking force from the horse with a shorter contact time. At the moment of horse take-off, reactive hip extension of the top-level athlete enhanced propulsive take-off velocity and hip posture during post-flight phase. Conclusion: Even though a high velocity of the center of mass is important, the posture and interactive action during horse contact is crucial to post-flight performance and the advanced performance of Tsukahara vaults.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2001년도 정기총회 특별강연 및 춘계학술연구발표회(2)
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• pp.135-138
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• 2001

• 한국운동역학회지
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• 제24권4호
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• pp.317-327
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• 2014

As a single subject study, it was purposed to investigate kinematic differences between Yang Hak Seon vault (i.e., handspring forward and salto forward straight with triple twist, Yang-1 vault hereafter) and Tsukahara $1260^{\circ}$ twist with salto forward straight (Yang-2 vault hereafter) in gymnastics. Yang Hak-Seon (23 years, 160 cm, and 52 kg) voluntarily participated in this study. Motion capture system, consisting of fourteen cameras, were used to measure Yang-2 vault with the sampling rate of 200 Hz. Twenty six reflective markers were placed on major anatomical points of 15 body segments. Successful two trials of Yang-2 vault were collected and analyzed for the comparison. Compared Yang-1 results were based on the previous study of Park and Song (2012). Results indicated superior linear kinematics of Yang-1 vault to those of Yang-2 vault before the touchdown of vault table. However, Yang-2 vault revealed superior angular kinematics to Yang 1 vault showing more trunk twist angle (a triple and a half twist) and its faster angular velocity during the airborne. The Yang 2 vault could has advantage of increasing angular motion than Yang 1 vault as a result of a half turn off the springboard onto the vault table and a sequential touchdown of the hands.

• 한국운동역학회지
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• 제14권3호
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• pp.135-147
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• 2004

This study was conducted to investigate the technical factors of Lu Yu Fu vault actually performed by three men gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu through the DLT method of three dimensional cinematography. To analyze these vaults, the instant events of Lu Yu Fu were set in the board touchdown(BTD), the board takeoff(BTO), the horse touchdown(HTD), the horse takeoff(HTO), the peak height(PH), the mat touchdown(MTD) respectively and the phases of that vault were set in the board contact(BC), the preflight(PRF), the horse contact(HC), the postflight(POF), the grounding on mat(GM) respectively After calculating the performance times, the CG displacement velocity, the kinetic energy impulse reaction force moment arm torque at the horse, the released angle piked angle addressed angle, the angular momentum angular velocity of whole body in x axis, and the horizontal displacement between the feet and CG, the following conclusions were reached. To perform the better Lu Yu Fu vault, a gymnast must have the large horizontal velocity of whole body with fast run-up, decrease the duration time and the horizontal vertical displacement of whole body in PRF, have the enough time to judge the correct magnitude and direction of force to brake or push the horse so as to lengthen the HC duration time at any cost. Also it is desirable to increase the horizontal vertical displacement of whole body in POF if possible, maintain the adequate piked position to decrease the angular velocity of whole body in x axis, prepare the grounding on mat previously and delay the release of the hand from the body to keep the angular momentum.

• 한국운동역학회지
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• 제17권2호
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• pp.93-101
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• 2007

The purpose of this study was to analyze the research trends of artistic gymnastics on the kinetics. This study analyzed the 76 published papers in the Journal of Korean Alliance for Health, Physical Education, Recreation & Dance and Korean Journal of Sport Biomechanics between 1995 and 2006. Papers were split into two groups for analysis, 1995-1999 and 2000-2006, and classified according to research methods, areas, and main topics. Conclusions are as follow. First, method of research were kinematical research(80.3%), kinetic(17.1%), and EMG research(2.6%). Second, areas of research were hi-bar(31.6%), vault(23.7%), parallel bars(21.1%), floor exercise(13.2%), rings(3.9%), balance beam(3.9%), uneven bars(2.6%). Last, main topic of research were focused on vault Tsukahara skill(13.9%), hi-bar flight skill(11.4%), parallel bars support skill(10.1%), hi-bar dismount skill(8.9%), floor exercise salto skill(8.9%).

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.244-247
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• 2002

We examined a possibility to use inorganic plastic scintillator, which has the effective atomic number close to that of human soft tissue, for the measurement of dose distributions in a shorter time period. The method was to irradiate a block of plastic scintillator as a phantom, and to measure the distribution of the scintillation light by a wave length analyzer through a thread of plastic optical fiber. By irradiating the diagnostic x-ray, we observed the emission spectrum of the scintillation light from the scintillator. It showed a peak at around 420nm with a full width of 140 nm. The emission spectrum was integrated to determine the total number of photons. The dependences of the amount of photons on the irradiated dose were measured. The results of the experiment show that the amount of emission light is in proportional to the irradiated dose. From this fact, we conclude that the present method can be used for the measurement of the depth dose distribution of the diagnostic x-rays.

• Asian-Australasian Journal of Animal Sciences
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• 제17권5호
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• pp.633-637
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• 2004

The experiment of silage for preservation of fresh Italian ryegrass (Lolium multiflorum) was carried out to examine whether the fermentation quality and microbial degradation in the rumen can be altered by the treatment of amino acids fermentation byproduct (AFB). The plant was ensiled for 40 days with 4 treatments of different ratios of AFB and sugarcane molasses (SCM) mixture. The treatment 2 (T2, AFB:SCM=100:0) and treatment 3 (T3, AFB:SCM=40:60) silages showed higher (p<0.05) concentrations of lactic acids, lower (p<0.05) pH and dry matter (DM) losses than the Control (T1, none additive) and treatment (T4, AFB:SCM=0:100) silages. The treatments 2 and 3 contained higher (p<0.05) DM and crude protein contents in silages compared to treatments 1 and 4 silages. The NDF, ADF and cellulose contents were also lower (p<0.05) in T2, T3 and T4 silages than T1 silage and fresh material before ensiled. The in situ rumen DM, NDF, ADF, hemicellulose and cellulose degradability was also higher (p<0.05) in T2, T3 and T4 silages than T1 silage, while the highest improvement was achieved with addition of AFB:SCM at level of 40:60 at ensiling. The result in this study indicates that the addition of AFB and SCM additives improved the silage fermentation and cell wall degradability of Italian ryegrass silage.

• 한국산학기술학회논문지
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• 제21권2호
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• pp.167-174
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• 2020

본 연구는 세계적인 선수를 대상으로 남자 기계체조 도마 종목에서 로페즈 기술을 수행했을 때 성공 동작과 실패 동작에 따라 운동학적 차이를 비교 분석하였다. 연구대상은 올림픽 금메달리스트 YHS 선수(나이: 27세, 신장: 160cm, 체중: 53kg중)이였고, 14대의 적외선 고속카메라를 이용하여 도마 동작을 촬영하였다. 원하는 동작 자료획득과 분석을 위해 19mm 반사 마커 26개를 해부학적 주요지점에 부착시켰고, 15개 분절 신체모델을 사용하여 운동학적 변인 계산을 실시하였다. 분석 결과 첫째, 구름판 접촉구간에서 성공 동작의 소요시간이 실패 동작보다 길었으며, 성공 동작은 슬관절의 가동범위를 실패 동작보다 크게 하였다. 둘째, 제1비약에서 성공 동작과 실패 동작의 소요시간은 동일하였다. 성공 동작은 실패 동작보다 짧은 수평이동을 했으며, 높은 수직위치와 도마 착지각을 보였다. 셋째, 도마 접촉구간에서 성공 동작의 소요시간이 실패 동작보다 짧았다. 성공 동작은 도마접촉 순간에 실패 동작보다 좌측 견관절각을 크게 하였다. 넷째, 제2비약에서는 성공 동작의 소요시간이 실패 동작보다 길었으며, 긴 수평이동을 나타냈다. 성공 동작은 도마이륙 순간 우측 견관절각을 크게 하였고, 비틀기 각속도는 빨랐다. 종합하면 YHS 선수가 안정적인 로페즈 기술을 구사하기 위해서는 도마접촉 순간에 높은 자세로 진입하여 도마이륙 순간에서는 우측 견관절각을 크게하여 빠른 비틀기 각속도를 만들어야 한다. 최대높이와 착지 순간에서는 좌·우견관절각을 작게하여 관성모멘트를 줄이고 신체중심을 낮춰야 할 필요가 있다.