• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.203-212
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• 2008

The purpose of this study is to propose appropriate model for 3 staged Didimsae movement to Jajinmori rhythm and to provide information for ideal foot step movements. For the locational change of body center, the height of body center is lowered at the moment of forward step and during forward intersection of the feet, forward direction linear motion is converted to vertical motion to maintain stability. Speed change of body center reduces flow of body on step forward moment and controls rapid forward movement for stabled movement and position when preventing fast forward horizontal direction movement of centroid speed while knee joint and foot joint are vertically risen for heel bone contacts the ground. For angle changes of joints, in order to prevent hyperextension of lower leg, hip joint is extended and knee joint is curved to secure stability of movement for smooth curves and extension. When centroid of foot joint is moved from top of the feet to whole foot sole and when left foot makes dorsal curve, stabled movement is accomplished.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.593-603
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• 2009

In this paper, we propose a new integrated computer vision system designed to track multiple human beings and extract their silhouette with an active stereo camera. The proposed system consists of three modules: detection, tracking and silhouette extraction. Detection was performed by camera ego-motion compensation and disparity segmentation. For tracking, we present an efficient mean shift based tracking method in which the tracking objects are characterized as disparity weighted color histograms. The silhouette was obtained by two-step segmentation. A trimap is estimated in advance and then this was effectively incorporated into the graph cut framework for fine segmentation. The proposed system was evaluated with respect to ground truth data and it was shown to detect and track multiple people very well and also produce high quality silhouettes. The proposed system can assist in gesture and gait recognition in field of Human-Robot Interaction (HRI).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.806-811
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• 2005

The robot to search and rescue is used in narrow space where human cannot approach. In case of this robot, it can overcome obstacles such as wrecks or stairs etc. Also, this robot can do various locomotion for each object. In this reason, an articulated robot has advantages comparing with one module robot. However, the existing articulated robot has limits to overcome vertical passages. For expanding contacted territory of robot, a novel mechanism is demanded. In this paper, the novel mechanism of articulated mobile robot is designed for moving level ground and vertical passages. This paper proposes to change wheel alignment. The robot needs two important motions for passing vertical passages like pipe. One is a motion to press wheels at wall for not falling into gravity direction. The other is a motion that wheels contact a vertical direction of wall's tangential direction for reducing loss of force. The mechanism of the robot focused that two motions can be acted to use just one motor. Length of each link of robot is optimized that wheels contact a vertical direction of wall's tangential direction through kinematic modeling of each link. The force of pressing wall of robot is calculated through dynamic modeling. This robot composes four modules. This mechanism is confirmed by dynamic simulation using ADAMS program. The articulated mobile robot is elaborated based on the results of kinematic modeling and dynamic simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1345-1350
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• 2010

Sit-to-stand movement is a basic movement in daily activities. On the basis of this movement, the biomechanical functions of a person can be evaluated. The study of the joint kinematics, moment, and muscle coordination is necessary to understand the characteristics of the sit-to-stand movement. We have developed a motion-based program for inverse dynamics analysis and the electromyogram-based program for muscle force prediction. The joint kinematics and the kinetic results estimated on the basis of obtained motion data, ground reaction force, and electromyogram signals were compared with those reported in previous studies, and the muscle forces determined by the two methods were compared with each other. The methods and programs developed in this study can be used to understand biomechanics and muscle coordination involved in basic movements in daily activities.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.136-142
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• 2015

In the paper, a design method of knee and pelvis joint in the biped robot is proposed for shock absorption and gravity compensation. Similarly to the human's body, the knee joints of the biped robot support most body weight and get a shock from the landing motion of the foot on the floor. The torque of joint motor is also increased sharply to keep the balance of the robot. Knee and pelvis joints with the spring are designed to compensate the gravity force and reduce the contact shock of the robot. To verify the efficiency of the proposed design method, we develope a biped robot with the joint mechanism using springs. At first, we experiment with the developed robot on the static motions such as the bent-knee posture both without load and with load on the flat ground, and the balance posture on the incline plane. The current of knee joint is measured to analyze the impact force and energy consumption of the joint motors. Also, we observe the motor current of knee and pelvis joints for the walking motion of the biped robot. The current responses of joint motors show that the proposed method has an effect on shock reduction and gravity compensation, and improve the energy efficiency of walking motions for the biped robot.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.591-605
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• 2006

The purpose of this study is to investigate the relationship between lunar and earth rotation, by quantitatively describing the rotation of lunar configuration which is observed during the lunar diurnal motion. Our research suggests that observation of the lunar diurnal motion could be used as a study topic in the earth science courses. The rotation of the lunar configuration is an apparent phenomenon that can be seen when an observer. standing on the ground. looks at the moon as if the lunar dark configuration rotates on the basis of horizontal line. In spite its competence as a study topic because it is observable by naked eyes, there are only few major textbooks that introduce this phenomenon with regard to the earth rotation. Therefore, this study induced the mathematical principle of the lunar rotation in detail and proposed that this could be developed as a scientific inquiry through practical observation. In addition, an analytical proof and qualitative method of explanation of the lunar reverse rotation were also presented.

• Korean Journal of Applied Biomechanics
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• v.23 no.4
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• pp.377-385
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• 2013

Fall is very fatal accident causes death to older people. Shoe may affect to fall. Shoe influences risk of slips, trips, and falls by altering somatosensory feedback to the foot. The purpose of this study was to investigate the analysis of non-slip shoes for older people and influence on older people's lower extremity. For this study twenty three healthy older people were recruited. Each subjects walked over slippery surfaces (COF 0.08). Four pairs of non-slip shoes (shoe A had the greatest COF, 0.23 while shoe B, C, and D had smaller COF relatively) for older people were selected and tested mechanical and biomechanical experiment. For data collection motion capture and ground reaction forces were synchronized. There were statistically significant differences for slip-displacement, coefficient of friction, braking force, propulsion force, knee range of motion and knee joint stiffness by shoes. It was concluded that shoe A was the best for non-slip function because of the lowest slip displacement, the highest braking and propulsion forces, and the highest mechanical and biomechanical coefficient of friction where as shoe B, C, D were identified as a negative effect on the knee joint than shoe A. To prevent fall and slip, older people have to take a appropriate non-slip shoes such as shoe A.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.181-189
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• 2005

To know the proper impact posture and changes for the various clubs, changes of impact variables according to the change of golf club length was investigated. Swing motions of three male low handicappers including a professional were taken using two high-speed video cameras. Four clubs iron 7, iron 5, iron 3 and driver (wood 1) were selected for this experiment. Three dimensional motion analysis techniques were used to get the kinematical variables. Mathcad and Kwon3D motion analysis program were used to analyze the position, distance and angle data in three dimensions. Major findings of this study were as follows. 1. Lateral position of the head remained more right side of the target up to 3.5cm compared to the setup as the length of the club increased. 2. Left shoulder raised up to 5cm and right shoulder lowered up to 2.5cm compared to setup. The shoulder line opened slightly (maximum 11 degrees) to the target line. 3. Forward lean angle of the trunk decreased up to 4 degrees (more erected) compared to setup. 4. Side lean angle of the trunk increased compared to setup and increased up to 16 degrees as the club length increased. 5. The pelvis moved to the target line direction horizontally and opened up to 31 degrees. Right hip moves laterally to the grip position at the setup. 6. Flexion of the left leg maintained almost constantly but the right leg flexed up to 11 degrees compared to setup. 7. Left arm is straightened but the right arm flexed about 20degrees compared to straight. 8. Center of the shoulders were in front of the knees and toes of the feet. 9. Hands moved to the left (8.7cm), forward (5.7cm) and upward (11.6cm) compared to the setup. This is because of the rotation of pelvis and shoulders. 10. Shaft angle to the ground was smaller than the lie angle of the clubs but it increased close to the lie of the clubs at impact.

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.720-726
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• 2000

The analytic gradient method for the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) energy has been extended to employ a reduced molecular orbital (MO) space. Not only the innermost core MOs but also some of the outermost virtua l MOs can be dropped in the reduced MO space, and a substantial amount of computation time can be reduced without deteriorating the results. In order to study the magnitudes and trends of the effects of the dropped MOs, the geometries and vibrational properties of the ground and excited states of BF, CO, CN, N2, AlCl, SiS, P2, BCl, AIF, CS, SiO, PN and GeSe are calculated with different sizes of molecular orbital space. The 6-31 G* and the aug-cc-pVTZ basis sets are employed for all molecules except GeSc for which the 6-311 G* and the TZV+f basis sets are used. It is shown that the magnitudes of the drop-MO effects are about $0.005\AA$ in bond lengths and about 1% on harmonic frequencies and IR intensities provided that the dropped MOs correspond to (1s), (1s,2s,2p), an (1s,2s,2p,3s,3p) atomic orbitals of the first, the second, and the third row atoms, respectively. The geometries and vibrational properties of the first and the second excited states of HCN and HNC are calculated by using a drastically reduced virtual MO space as well as with the well defined frozen core MO space. The results suggest the possibility of using a very smalI MO space for qualitative study of valence excited states.

• Korean Journal of Applied Biomechanics
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• v.29 no.3
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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.