골프 스윙시 어드레스부터 백스윙탑까지의 소요시간에 대한 역학적 분석

백병주,이기천,이요열 연세대학교 체육연구소 2002 체육연구논문집 Vol.9 No.1

본 연구의 목적은 골프스윙시 어드레스부터 백스윙 탑까지의 운동학적 분석을 하는데 있다. 피험자로는 7년의 경력과 핸티캡 3의 대학 골퍼 5명으로 하였다. 실험은 2대의 16mm 고속카메라(photosonic co.)를 사용하였으며, 이때 촬영속도는 300frame/sec로 하였다. 자료분석은 3차원 영상분석하였으며, 프로그램은 KWON3D를 사용하였으며, 다음과 같은 결론을 얻었다. 어드레스에서 백스윙 탑까지의 소요시간은 1.12초, 임팩트까지는 1.38초, 그리고 백스윙 탑에서 임팩트까지의 소요시간은 0.26초로 나타났다. 국면별 누적시간은 제 1국면이 0.47초(31.77%), 2국면이 1.12초(77.08%), 3국면이 1.38초(96.03%) 그리고 4국면이 1.44초(100%)로 나타났다. The purpose of this study was to analyze kinematic to top of back swing from address in golf swing. The samples of this study were five university golfers who had 7 years career, 3 handicap. The experiment of this study was used two 16mm high speed cameras (Photosonic co.) its speed was 300frame/sec. Data analysis of this study was three-dimentional cinematography using KWON3D program package. As a conclusions the time elapsed (TE) from address to back swing top was 1.12 sec. and TE to impact was 1.38sec., TE from back swing top to impact was 0.26sec. TE during 1st phase was 0.47sec. (31.77%), TE during 2nd phase was 1.12sec.(77.08%), TE during 3rd phase was 1.38sec. (96.03%) , and TE during 4th phase was 1.44sec.(100%).

Heavy Metal Pollution Characteristics of Particulate Matter in the Vicinity Import- Export Harber

( Yo-jae Cheon ),( Ji-hyun Kim ),( Young-koo Park ) 한국폐기물자원순환학회 2011 ISWA Vol.2011 No.0

반응면 기법과 크리깅 기법을 이용한 설계공간의 타당성 향상

구요천(Yo-Cheon Ku),전용희(Yong-Heu Jeon),김유신(Yu-Shin Kim),이동호(Dong-Ho Lee) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.2

본 연구에서는 근사모델을 이용하여 설계공간의 타당성을 높일 수 있는 방법을 제시하였다. 이때 설계공간을 이동시키기 위한 기준으로 Chebyshev Inequality를 사용하였다. 이를 공탄성을 고려한 항공기 익형 설계문제에 적용함으로써 타당성이 크게 향상됨을 확인하였으며 이렇게 구한 설계공간 내에서 최적화를 수행함으로써 보다 우수한 최적값도 얻을 수 있었다. 즉 설계공간 내에서 주어진 제약조건을 만족할 확률이 증가하였으며, 설계공간을 이동시킴으로써 보다 우수한 최적점이 설계공간 내에 포함되었다고 할 수 있다. 또한 이 과정에서 반응면 모델과 크리깅 모델, 두 가지 근사모델을 사용하여 정확성과 효율성, 실험점에 대한 강건성 등을 비교하였으며, 본 연구에서 설계한 문제의 경우 비교적 선형적인 특징으로 인해 반응면이 보다 우수한 결과를 보여줌을 확인하였다. In this research, a procedure to improve the feasibility of design space is proposed by an approximation model. The Chebyshev Inequality is used as the criterion of modification of design space. This procedure is applied to the aero-elastic transonic wing design problem and the feasibility of the design space is greatly improved. Also the optimization results are improved by appling this procedure. That is, the probability to satisfy all imposed constraints is increased and the better design points are included in design space after this procedure. And the use of both a second-order response surface model and the Kriging model is investigated and compared in accuracy, efficiency, and robustness as approximation models in this procedure for different sampling methods. As a result, the second-order response surface model is more appropriate for our application than the Kriging model, because it is linear enough to be fitted well by the response surface model.

청소년 및 대학생 운동선수의 대퇴이두근 / 대퇴사두근 근력 비율: 체계적인 검토

천요한 ( Yo-han Cheon ),송종국 ( Jong-kook Song ),박태영 ( Tae-young Park ),정현철 ( Hyun-chul Jung ) 중앙대학교 학교체육연구소 2021 Asian Journal of Physical Education of Sport Scien Vol.9 No.6

하지 근력 비율은 운동 수행능력에 직·간접적으로 영향을 미치며, 불균형한 하지 근력 비율은 비접촉식 부상의 잠재적 원인이다. 따라서 본 연구는 운동선수의 하지 근력 비율을 평가한 선행연구를 체계적으로 분석하고 종합적으로 검토하기 위해 실시되었다. 체계적 검토를 위해 3개의 전자데이터 베이스에서 2명의 연구원이 논문을 검색하고 독립적으로 분석하였으며, 운동선수를 대상으로 진행된 연구만이 본 연구에 포함되었다. 선정된 연구들은 Modified Downs and Black checklist를 이용해 질적 평가를 진행하였다. 초기 검색 결과 3329개의 연구 중 기준을 충족하는 24개의 연구가 선정되었다. 검토된 연구들은 특히 높은 각 속도와 스포츠 종목에 따른 전통적 하지 근력 비율에 차이가 존재하였다. 그러나 현재까지 운동선수를 대상으로 기능적 하지근력 비율을 평가한 연구는 부족한 실정이며 전통적 하지 근력 비율 또한 여러 스포츠에서 차이가 존재하였기에 근육 불균형의 예측값인 0.6을 기준으로 모든 스포츠 종목에 적용하는 것은 고려되어야 할 사항이다. 따라서 근력 불균형을 평가하거나 부상 위험성 예측에 대한 특정 컷오프를 결정하기 위해서는 운동선수의 기능적 하지 근력 비율을 평가하는 추가연구가 필요하다. Lower extremity strength ratios can affect exercise performance directly or indirectly, and muscular imbalance is a potential risk factor for non-contact injuries. This review systematically examines previous studies to understand the differences between conventional and functional hamstring to quadriceps (H/Q) strength ratio in athletes. Two researchers independently conducted systematic searches in three electronic databases, and only studies involving athletes were included. The initial search yielded 3,329 articles but only 24 were considered for this study. Modified Downs and Black checklists were applied to examine the quality of the study. The average score of study quality was 10.46 of 13 points. Different velocities and sports athletes discovered variances in the conventional H/Q strength ratio. However, there are only few studies that examine the functional strength H/Q ratio, which could limit the ability to compare differences by sports. More studies that examine the functional strength H/Q ratio may be required in future research to understand the status of functional muscular imbalance in the lower extremity caused by sports.

Optimal cross-sectional area distribution of a high-speed train nose to minimize the tunnel micro-pressure wave

Ku, Yo-Cheon,Rho, Joo-Hyun,Yun, Su-Hwan,Kwak, Min-Ho,Kim, Kyu-Hong,Kwon, Hyeok-Bin,Lee, Dong-Ho Springer-Verlag 2010 Structural and multidisciplinary optimization Vol.42 No.6

터널 주행속도 향상을 위한 고속열차 전두부 형상 최적화

구요천(Ku Yo-Cheon),윤수환(Yun Su-Hwan),노주현(Rho Joo-Hyun),김규홍(Kim Kyu-Hong),이동호(Lee Dong-Ho),권혁빈(Kwon Hyeok-Bin) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-

The next generation of Korean high-speed train under development will be designed for the maximum operating speed of 350km/h and maximum speed of 400km/h. This high-speed operation may cause the noise and vibration problems around tunnel exit due to the higher micro-pressure wave than present level. In this study, the nose shape optimization was conducted for the countermeasure against these problems. Axi-symmetric solver was used for numerical simulation, and response surface was used for efficiency of optimization process. Also the multi-step optimization was conducted to find out more accurate optimal shape. Through these analysis and optimization, it was found out that the optimal nose shapes for minimization of micro-pressure wave are definitely different along the nose length variation. And the mechanism of micro-pressure wave reduction was closely investigated by the analysis of generation process of compression wave in tunnel. The results are expected to be used as design guideline for performance improvement of the next generatin of Korean high-speed train.

형상함수를 이용한 열차 전두부 설계기법 연구

구요천(Ku Yo-Cheon),노주현(Rho Joo-Hyun),윤수환(Yun Su-Hwan),곽민호(Kwak Min-Ho),이동호(Lee Dong-Ho) 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-

A nose shape is strongly related with the aerodynamic performances of train. Therefore shape definition and aerodynamic performance analysis are important for train nose shape design. In this study, a new design method was suggested for train nose shape design by configuration function. To this end, the nose shape was classified by box type and each box shape is defined. After that the 3-D shape of train was defined as several mathematical functions by combination of each box shape. Also it was shown that the wind shield of driver"s seat and complex curves of surface can be expressed using superposition of functions. This methodology can be used for grid generation of numerical analysis, and applied to aerodynamic optimization design of nose shape.

하이터를 이용한 하부 열차풍 감소에 대한 연구

구요천(Ku Yo-Cheon),김종용(Kim Jong-Yong),윤수환(Yun Su-Hwan),노주현(Rho Joo-Hyun),이동호(Lee Dong-Ho),권혁빈(Kwon Hyeok-Bin) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-

The ballast-flying, induced by strong underbody train gust, may damage train underbody, wheel and even cause the safety problems. For this reason, a heighter is being used to prevent the ballast-flying phenomenon through underbody flow reduction. In this research, flow field around a heighter is numerically simulated. And the parametric study of various heighter shapes is performed to find out more effective heighter shape. Also the ballast-flying probabilities are calculated for various ballast types and train speeds.

Disparity Estimation using Belief Propagation for View Interpolation

Cheon Lee,Yo-Sung Ho 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

In this paper, we propose a modified disparity estimation method using belief propagation (BP) for view interpolation. The view interpolation method generates an arbitrary intermediate view image with disparity. To extract disparities, we modified the BP based stereo matching algorith which solves the problem using Bayesian belief propagation. We propose two methods to improve accuracy of disparity. The first is about the matching cost computation. Instead of using pixel differences between corresponding pixels, we use block cost computation. The second is quad-tree region dividing for disparity refinement. Since narrow and accurate search range can guarantee accuracy of estimation, we divide the image into four distinct regions and refine disparities. By experiments, we improved quality of the interpolated images over 1~4 dB on average.

Overview of View Synthesis Prediction for Multi-view Video Coding

Yo-Sung Ho,Cheon Lee,Kwan-Jung Oh 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

With a wide range of viewing angles, the multi-view video can provide more realistic feeling at arbitrary viewpoints. However, because of a huge amount of data from multiple cameras, we need to develop an efficient coding method. One of the promising approaches for multi-view video coding is view synthesis prediction which generates an additional reference frame. In this paper, we explain the principal idea of view synthesis prediction and propose a view interpolation and coding scheme. For view interpolation, we employ initial disparity estimation, variable block matching, and disparity error correction methods. After generating an intermediate view image, we apply a ‘VIP Ppicture’ coding method with the additional reference frame, where we have five additional motion estimation modes and a modified motion vector prediction scheme. By computer simulations, we have improved the coding gain by 0.66 ㏈ on average for the well synthesized sequences.