• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.213-226
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• 2008

E. H. KIM, E. S. CHOI, D, H. NAM, S. S. KIM, J. W. CHUNG and T. W. KIM, The Instrumenfal Development for Pulling . Reaping Training & Measuring in Judo.Korean Jiurnal of Sport Biomechanics, Vol. 18, No. 1, pp. 213-226, 2008. The purpose of this study was to develop a judo-doll uke(partner : doll-uke) for training and measurement applicable to pulling, pushing and reaping in judo. In Judo the most common techniques consist of the pulling, pushing and sweep which all need to be practiced with a partner. So the research needs to develop a measurement system that can be used to evaluate the forces involved with these techniques. Also the Doll-Uke must be developed so that judokas can train alone. After the manufacture of Doll-Uke the usefulness of it must be evaluated. The height of a Doll-Uke is l70cm and its weight is 50kg. Doll-Uke was developed with a trunk angle of 55 and the lower extremities of an angle of 45. The Doll-Uke can also measure the forces developed during the pulling, pushing and sweep. Due to the ability of the system to measure the forces while preforming Judo techniques feedback can be provided to the Judokas to improve their performance.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.197-205
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• 2007

The purpose of this study is to analyze the muscle activations and Ground Reaction Force(GRF) in university judo players, and provide the guide of training in Judo. Using surface electrode electromyography(EMG), we evaluated muscle activity in 5 university judo players during the Judo Uke Movements. Surface electrodes were used to record the level of muscle activity in the Tibialis Anterior, Rectus Femoris, Elector Spinae, Gluteus Maximus, Gastrocnemius muscles during the Uke. These signals were compared with %RVC(Reference voluntary contraction) which was normalized by IEMG(Integrated EMG). The Uke was divided into four phases : Kuzushi-1, Kuzushi-2, Tsukuri, Kake. The results can be summarized as follows: 1. The effective Uke Movements needs to short time in the Kake Phase 2. The Analysis of Electromyography of Uke Movements in Supporting Leg; TA(Tibialis anterior) had Higher %RVC in the Kuzushi Phase, RF(Rectus Femoris) had Higher %RVC in the Tsukuri Phase, GM(Gluteus Maximus) had Higher %RVC in the Kake Phase 3. The ground reaction force for Z(vertical) direction was showed increase tendency in Kuzushi phase, Tsukuri phase and decrease tendency in Kake phase.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.191-203
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• 2005

It was to study a following research of "A Kinematical Traits Analysis when Performing Uchimata(inner thigh reaping throw) by Posture and Voluntary Resistance Levels(VRL) of Uke in Judo[1]" and. "A Case Study of Center of Gravity(COG) when Performing Uchimata(inner thigh reaping throw) by Posture and Voluntary Resistance Levels(VRL) of Uke in Judo[II]". The purpose of this study was to analyze an angular momentum of trunk and lower extremity when performing uchimata by two postures and voluntary resistance levels(VRL) of uke(reciver) in Judo. The subjects, who were one male judoka(YH) for 1992 Barcelona Olympic Games Olympian(silver medalist), was filmed on two S-VHS 16mm video cameras(60fields/sec.) through 3-dimensional motion analysis methods, that postures of uke were shizenhontai (straight natural posture:NP) and jigohontai (straight defensive posture:DP), VRL of uke were 0% and 100%, respectively. The variables were angular momentum of trunk, lower extremity of attacking leg and supporting leg of tori(the thrower). The data of this study collection were digitized by SIMI Motion Program computed the mean values and the standard deviation calculated for each variables. When performing uchimata according to each posture and VRL of uke and classifying. From the data analysis and discussion, the conclusions were as follows : Angular momentum of trunk when performing uchimata was showed the largest among another angular momenta, and the posture displayed more different than resistant of uke(reciver), but the pattern similar in judo. Angular momentum of trunk of X axis was the largest and Y, Z axis order. Angular momentum of attacking the thigh-leg when performing uchimata was showed the largest among another angular momenta, and the posture displayed more different than resistant of uke(reciver), X axis and Y axis similar, but angular momentum of Z axis of thigh-leg the largest, in kake(application) event in 0% resistance of DP than other variables. Angular momentum in X,Y axis of attacking the lower-leg when performing uchimata was showed that the resistance level displayed more different than posture, but Z axis the largest, in kake(E3) phase in 0% resistance of DP than other variables as same thigh-leg, and the largest from tsukuri(set-up:E2) to kake(E3) phase. X and Z axis Angular momentum of supporting the thigh-leg were similar, regardless of posture and resistance of uke, but Y axis was resistance level. Angular momentum of supporting the thigh-leg was showed the largest in X axis, increased from EO event to E2, and decreased in E3, and angular momenta of Y, X axis were showed the largest in kuzushi(balance breaking) phase when performing uchimata. Angular momentum of supporting the lower leg were similar pattern, regardless of posture and resistance of uke, in Y axis, resistance displayed more difficult the position in NP, and showed opposite angular momentum in tsukuri phase. In conclusion, angular momentum of trunk when performing uchimata was showed the largest, and pattern was similar, regardless of posture than resistant of uke(reciver), magnitude and direction were different each other, and uchimata was Ashi -waza(foot and leg techniques) division but important of trunk action.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.237-257
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• 2005

It was to study as a following-research of "A Case Study on Center of Gravity(COG) Analysis when Performing Uchimata(inner thigh reaping throw) by Posture and Voluntary Resistance Levels(VRL) of Uke in Judo[I]". The purpose of this study was to analyze the COG variables when performing uchimata(inner thigh reaping throw) by two postures and voluntary resistance levels(VRL) of uke(reciver) in Judo. The subjects, who were one male judoka(YH) for 1992 Barcelona Olympic Games Olympian(silver medalist), and one male trainee; Y.I.University representative member (SDK), and were filmed on two S-VHS 16mm video cameras(60fields/sec.) through 3-dimensional motion analysis methods, that postures of uke were shizenhontai (straight natural posture) and jigohontai(straight defensive posture), VRL of uke were 0% and 100%, respectively. The kinematical variable was COG variable, distance of COG, and distance of resultant COG between uke and tori(the thrower), velocity and acceleration of COG. The data of this study collection were digitized by SIMI Motion Program computed the mean values and the standard deviation calculated for each variables. When performing uchinmata according to each posture and VRL of uke and classifying. From the data analysis and discussion, the conclusions were as follows : 1. Displacement of COG Subject YH, COG was the highest in kuzushi(balance -breaking), vertical COG was low when following in tsukuri(positioning; set-up), kake(application; execution), and COG was pattern of same character each postures and resistance, respectively. Subject SDK, COG was low from kumikata(engagement positioning) to kake, and COG was that each postures and resistance were same patterns, respectively. Subject YH, SDK, each individual, postures and resistance, vertical COG was the lowest in kake phase, when performing. 2. Distance of COG between uke and tori The distance of COG between uke and tori when performing, subject YH was $0.64{\sim}0.70cm$ in kumikata, $0.19{\sim}0.28cm$ in kake, and SDK was $0.68{\sim}0.72cm$ in kumikata, $0.30{\sim}0.42\;cm$ in kake. SDK was wider than YH. 3. Distance of resultant COG between uke and tori The distance of resultant COG between uke and tori when performing, subject YH was $0.27{\sim}0.73cm$ from kumikata to kake. and SDK was $0.14{\sim}0.34cm$ in kumikata, $0.28{\sim}0.65cm$ in kake. Jigohontai(YH:$0.43{\sim}0.73cm$,SDK:$0.59{\sim}0.65cm$) was more moved than shizenhontai(YH:$0.27{\sim}0.53cm$, SDK: $0.28{\sim}\;0.34cm$). 4. Velocity of COG The velocity of COG when performing uchimata, subject YH was fast anterior-posterior direction in kuzushi, ant.-post. and vertical direction fast in tsukuri and kake. SDK was lateral, ant.-post. and vertical direction in kuzushi, ant.-post. and vertical direction in tsukuri and ant.-post. direction in take, respectively. 5. Acceleration of COG The acceleration of COG when performing uchimata, The trend of subject YH was showed fast vertical direction in kuzushi and tsukuri, ant.-post. and vertical direction fast in kake. The trends of SDK showed lateral direction in kuzushi, lateral and ant.-post. direction in tsukuri and ant.-post. direction in kake, respectively.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.235-257
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• 2004

The purpose of this study was to analyze the kinematical traits variables when performing Uchimata(inner thigh reaping throw) by Voluntary Resistance Levels(VRL) and two postures of Uke in Judo. The subjects, who were one male judoka(YH) for 1992 Barcelona Olympic Games, and one male trainee Y. I. University representative member(SDK) and were filmed on two S-VHS 16 mm video cameras(60fields/sec.), that posture of Uke were Shizenhontai(straight defensive posture) and Jigohontai(straight natural posture), VRL of Uke were 0% and 100%. The kinematical variables were temporal(total time-required: TR), potures and COG variables etc., The data of this study collection were digitized by SIMI Motion Program computed the mean values and the standard deviation calculated for each variables. When performing according to each posture and VRL, from the data analysis and discussion, the conclusions were as follows : 1. Temporal variables total time-required(TR) when performing Uchimata was shown the shortest time YH than SDK by each posture and VRL. TR of each posture were shown the shorten trends or equal in DP by lower than NP, In existence and / or nonexistence of VRL was shown the shorten trends in VRL 0% than 100% of Uke. 2. Posture variables : In attacking right knee angle, YH was performing flexion($147{\rightarrow}103degree$) from Tsukuri(set-up) to Kake(execution) in regardless of postures and VRLs, SDK was performing not exchange extension and flexion in VRL 100%, and extension($120{\rightarrow}142degree$) in VRL 0%, respectively. In supporting left hee angle, YH was performing extension($119{\rightarrow}163degree$) from Tsukuri(set-up) to Kake(at(execution) in regardless of postures and VRLs, SDK extension($93{\rightarrow}139degree$), respectively. In attacking right hip angle, from Tsukuri to Kake, YH was performing extension($133{\rightarrow}169degree$), except in VRL 0%($156{\rightarrow}137degree$) NP, SDK was performing flexion($159{\rightarrow}126degree$) accept in VRL 100%($149{\rightarrow}152degree$) NP, In left hip angle, from Tsukuri to Kake, YH was performing flexion NP(70, 50degree) more than DP(27, 57degree), SDK was performing flexion DP(73, 52degree) more than NP(34, 20degree). 3. COG variables : When performing Uchimata, vertical COG variables was shown YH(:$2{\sim}8cm$), SDK(:$15{\sim}24cm$) lower than Uke's COG level position, in existence and / or nonexistence of postures and VRL, during Kake as maximum force point of throwing techniques in Judo.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.167-183
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• 2005

The purpose of this study was to analyze the kinetical variables of the lower extremity joints when performing uchimata(inner thigh reaping throw) by uke(receiver)'s two posture(shizenhon tai), jigohon tai), by voluntary resistance level(VRL) in judo. The subjects, who were for 3 male Korean national representative judokas(elite group : EG) and 3 male representative judokas of Korean University(non-elite group: NEG), and were filmed 4 DV video cameras(60fields/sec.), that posture of uke were shizenhon-tai (straight natural posture), jigohon-tai(straight defensive posture), VRL of uke was 0%. The selected trials were subject to 3-dimensional film motion analysis and ground reaction force(MRF) analysis. The kinetical variable of this study were temporal, postures( ankle and knee angle of attacking leg), that were computed through video film analysis, MRF at events were obtained from the ground-reaction force analysis by AMTI force plate system. When performing uchi-mata according to each posture and by VRL, from the data analysis and discussion, the conclusions were as follows : 1) Temporal variables : total time-required(TR) when performing uchi-mata was shown EG 0.13sec the shorter than NEG(o.77sec.) in shizenhon-tai. and EG 0.17sec the shorter than NEG(o.76sec.) in jigonhon-tai. Also, all of two groups' jigohon-tai(0.68sec.) were faster than shizenhon-tai(0.71 sec.). 2) The posture variables : The angle of ankle in attacking when performing were plantar flexion in EG, and dorsi flexion in NEG by shizenhon-tai and jigohon-tai posture. The angle of knee in attacking when performing were extension in EG and NEG, but range of extension in EG were larger than in NEG. 3) MRF : Vertical MRF when performing uchi-mata was shown the strongest in the 2nd stage of kake phase(2.23BW) by EG in both posture, and it was same value by NEG(2.23BW), but shizenhon-tai (2.28BW), jigohon-tai(1.64BW), respectively.

• Proceedings of the Ginseng society Conference
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• 1980.09a
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• pp.137-141
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• 1980

• International Journal of Aeronautical and Space Sciences
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• v.18 no.2
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• pp.365-377
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• 2017

In this paper, we propose a method to identify the parameters of a rotorcraft slung load system using the modal characteristics of a flexible cable. The proposed method estimates the length of the cable and the mass of the payload by means of a frequency analysis. Dynamic equations of the slung load system with the flexible cable are derived using Udwadia-Kalaba equation (UKE) in order to build a simulation program, and the similarity of the simulated slung load movement is verified by comparison with flight test results. Using the computer simulation program, we show that the proposed method works well within various parameter ranges.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.11
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• pp.1124-1129
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• 2006

In this paper, in-flight alignment algorithm using UKF is presented for an SDINS aided by SSBL or GPS system under large initial heading error. The EKF usually applied for this task. This approximates the propagation of mean and covariance accurate to first-order only. To overcome this limitation, the unscented transformation that achieves second order approximation is applied to the in-flight alignment. To analyze the performance of the proposed method, simulations for S-type trajectory are carried out. The results show that performance of EKF and UKF are the almost same when the initial heading error is smaller than $30^{\circ}$, but UKF has a better performance for large initial heading error about $45^{\circ}$.

• Composites Research
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• v.31 no.6
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• pp.311-316
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• 2018

In the present study, the effect of GO in damping capacity of CF/epoxy laminates was studied via free vibration analysis. The composite laminates were manufactured by using vacuum assisted resin transfer molding technique. The damping properties of the prepared hybrid composites were determined in terms of natural frequency and damping ratio in free vibration test. The foremost aspire of this investigation was to compare the vibration properties i.e. natural frequency and modal damping of the prepared composites with the numerical results. The numerical study was carried out via FEA using $ANSYS^{TM}$ workbench software. The parametric study of the numerical models was also studied considering the beam free length and the beam thickness. It was found that the incorporation of GO enhanced the damping capacity of the composite and the variation of natural frequencies in mode1varied by 2-5% compared to the experimental study.