• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.744-749
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• 2007

Kinematic and kinetic analysis has been performed for Soft Golf swings utilizing realistic three dimensional computer simulations based on three dimensional motion tracking data. Soft Golf is a newly developed recreational sport in South Korea aimed to become a safe and easy-to-learn sport for all ages. The advantage of Soft Golf stems from lighter weight of the club and much larger area of the sweet spot. This paper tries to look into kinematic and kinetic aspects of soft golf swings compared to regular golf swing and find the advantages of lighter Soft Golf clubs. For this purpose, swing motions of older aged participants were captured and kinematic analysis was performed for various kinematic parameters such as club head velocity, joint angular velocity, and joint range of motions as a pilot study. Kinetic analysis was performed by applying kinematic data to computer simulation models constructed from anthropometric database and the measurements from the participants. The simulations were solved using multi-body dynamics solver. Firstly, the kinematic parameters such as joint angles were obtained by solving inverse dynamics problem based on motion tracking data. Secondly, the kinetic parameters such as joint torques were obtained by solving control dynamics problem of making joint torque to follow pre-defined joint angle data. The results showed that mechanical loadings to major joints were reduced with lighter Soft Golf club.

• The Journal of Korean Physical Therapy
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• v.31 no.1
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• pp.13-17
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• 2019

Purpose: This study examined the effects of flexible flatfeet on the accuracy of knee joint motions in closed and open kinetic chain tasks. Methods: Twenty-four healthy participants were recruited for this study. The subjects were divided into two groups using a navicular drop (ND) test: flexible flatfoot group (n=12, male: 6, aged $22.00{\pm}2.22years$) and age-matched control group (n=12, males: 6, aged $22.17{\pm}1.53years$). The accuracy of knee motion was measured quantitatively by tracing through the flexion and extension motion of the knee joints in the closed kinetic chain and the open kinetic chain. Results: There was a significant difference in the accuracy index between the groups in closed kinetic chain task, but there was no significant difference in the open kinetic chain task. In addition, there was a significant difference in the accuracy index between the closed kinetic chain and the open kinetic chain task in the flexible flatfoot group. In addition, a significant negative correlation was observed between the ND and accuracy index in the closed kinematic chain task, but there was no significant relationship between the ND and accuracy index in the open kinematic chain task. Conclusion: Flexible flatfeet can affect the accuracy of the adjacent joints, such as the knee joint in the closed kinematic chain.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.197-204
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• 2004

In this study we presented kinematic and kinetic data of foot joints using approximated equations and partial plantar pressure during gait. The maximum angular displacements of each tarsometatarsal joint were found to range from 4$^{\circ}$to 7$^{\circ}$ and the maximum moments were from 200Nㆍcm to 1500Nㆍcm. It was relatively wide distribution. Foot kinematic data calculated from the approximated equations, which were represented by the correlation between moment and angular displacement, and the data from motion analysis were similar. We found that the movements of foot joint were mainly decided by the passive characteristics of the joint when ground reaction force acts. The method of kinematic and kinetic analysis using approximated equations which is presented in this study is considered useful to describe the movements of foot joints in gait simulations.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.15-23
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• 2010

Purpose: This study was done to establish reference data for temporo-spatial, kinematic and kinetic parameters for normal Koreans as they age. Methods: Normal adults and children without a previous history of musculoskeletal problems were enrolled in this study. The normal subjects were divided by age into three groups: Group I: children ($11.95{\pm}0.29$ years); Group II: young adults ($23.90{\pm}3.67$ years); Group III: older adults ($71.40{\pm}4.08$ years). The temporo-spatial and kinematic data were measured using 6 MX3 cameras while each subject walked through a 10 m walkway at a self-selected speed. The kinetic data were measured using 2 force plates and were calculated by inverse dynamics. Results: Motion patterns are typically associated with a specific phase of the gait cycle. Our results were as follows: 1. There were significant differences between the different age groups in temporo-spatial parameters such as cadence, double support, time of foot off, stride length, step length, and walking speed. 2. There were significant differences between the groups in kinematic parameters such as range of motion (ROM) of the hip, knee and ankle in the sagittal plane, ROM of the pelvis, hip and knee in the coronal plane and ROM of the pelvis, hip and ankle in the transverse plane. 3. There were significant differences between the groups in kinetic parameters such as joint moments of force, joint mechanical power generation or absorption and ground reaction forces. Conclusion: The results of this study can be utilized (a) as a reference for kinematic and kinetic data of gait analysis in normal Koreans, and (b) as an aide in evaluating and treating patients who have problems relating to gait.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.940-958
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• 2016

The objective of this study was to analyze the kinematic and kinetic characteristics of two horticultural activities: seed sowing and planting plant. Thirty-one male university students (aged $26.2{\pm}2.0years$) participated in this study. Kinematic factors (movement times, peak velocity, joint angles, and grasp patterns) were assessed using a three-dimensional motion analysis system while the subjects performed the horticultural activities. Kinetic factors (muscle activation of eight upper-limb muscles: the anterior deltoid, serratus anterior, upper trapezius, infraspinatus, latissimus dorsi, biceps brachii, brachioradialis, and flexor carpi radialis) were assessed using surface electromyography. The acts of seed sowing and planting plant were comprised of five tasks which included six types of phases: reaching, grasping, back transporting, forward transporting, watering, and releasing. The movement times, peak velocity, joint angles, and grasp patterns were significantly different across the tasks involved in the horticultural activities. All eight muscles of the upper limbs were utilized during the horticultural activities, and the muscle activation of the serratus anterior was the highest compared to that of the other muscles tested. The kinematic and kinetic characteristics of these horticultural activities showed similar characteristics to reaching and grasping rehabilitation training and daily living activities. The present study provides reference data for common horticultural activities using a kinematic and kinetic analysis.

• Korean Journal of Applied Biomechanics
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• v.28 no.3
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• pp.151-158
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• 2018

Objective: In this study, we analyzed kinematic changes in the start phase of speed skating before and after physical training. Method: We introduced a new strength training program (2017) that was improved in terms of exercise type and intensity [%, one repetition maximum (1RM)] compared with the previous strength training program (2016). The new program was applied to elite speed skating athletes (four males and four females). To determine the improvement in starting technique, we recorded race images during the start phase of the 500-m race held in 2016 and 2017. The race images were collected using five high-speed cameras and kinematic characteristics of the start phase were analyzed by three-dimensional image analysis. Results: The 1RMs were improved by 11% on an average after the strength training. In 2017, records of four out of the eight athletes were shortened in terms of the initial lap time (100 m), and 500-m records were shortened in six athletes. The time to nine strokes was shortened in five athletes, and the ratio of correct kinetic chain was increased or maintained at a high level in six athletes. Conclusion: In this study, the new strength training program (2017), applied to elite speed skating athletes, showed a positive effect on starting technique and reduced the record times.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.395-404
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• 2012

This study was to perform the kinetic analysis of tucked backward salto on the balance beam. Eight women's gymnastics players(age: $15.88{\pm}2.45yrs$, career: $6.38{\pm}0.52yrs$, height: $152.38{\pm}7.35cm$, weight: $44.25{\pm}7.54kg$) of the I-region participated in this study. The kinematic variables were analyzed response time of motion, angle, velocity, acceleration and the kinetic variables were analyzed ground reaction force(GRF) of motion. For measure and analysis of kinematic and kinetic variables of this study, used to synchronized to 6 Eagle camera and 1 force plate, used to the Cortex(Ver. 1.0) for analyzed of variables. The results were as follows; To the kinematic variables of tucked backward salto on the balance beam, a time appeared longer landing than air rotation, changes of angle regulated segment of body smaller moment of inertia when air rotation, larger moment of inertia when releasing and landing. A velocity appeared fast motion when releasing and air rotation of body, but appeared more decelerations from landing and acceleration showed to be tended to velocity. A GRF appears jump more than twice the weight at the moment that showed the power of motion to all subject.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.225-234
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• 2020

Objective: The purpose of this study was to investigate the kinematic sequence patterns according to movement times during Karate choku-tsuki. Method: Ten Korea national Karate athletes participated in this study. Participants asked to perform jodan and chudan choku-tsuki. 30 infrared cameras were used to measure angular kinematic of elbow, shoulder, trunk, pelvis, hip, knee, ankle. Results: The two-way repeated measures ANOVA revealed significant effects for the joints (p<.05). But no significant effect for the movement time and interaction of joints x movement time existed for the kinematic sequence variables. Conclusion: For karate kumite players to reduce the movement time of punch, it is necessary to train kinematic sequences that allow each joint to rotate at a relatively similar timing.

• Korean Journal of Applied Biomechanics
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• v.24 no.3
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• pp.239-248
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• 2014

The purpose of this study was to quantify kinematic and kinetic characteristics of Yin-yang Bo gait according to their motor expertise, one of the Seokmun Ilwol martial art gait patterns. Yin-yang Bo gait pattern shows initial forefoot contact instead of heel contact, and increased time of stance phase time, internal-external rotation of ankle-knee-hip joints and pelvic. It aims to produce and store the more energy through continuous homeostasis of center of gravity (COG) and performance of stretch-shortening cycle. Some of these characteristics also were similar to the gait modification strategies for reducing knee adduction moment such as toe-out progression, medial thrust, internal rotation of hip joint. To identify the characteristics, four factors of expert Yin-yang Bo gait performance group were compared to that of none expert group; 1) angles of COG displacement and rotation 2) distal joint pre-rotation in internal-external rotation of ankle-knee-hip joints and pelvic, 3) invariability pelvic potential and pelvic segment total energy 4) knee abduction moment. Six healthy(three male) subjects participated in the experiment to perform Yin-yang gait pattern. Three-dimensional and force plate data were collected. Kinematic and kinetic data were compared between two groups using t-tests. Results showed that 1) the peak point of COG internal rotation angle was reduced in expert group, 2) kneeexternal and hip joint -internal and pelvic rotation angle peak frames were more near points in expert group.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.37.2-37.2
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• 2016

There exist scaling relations that link the mass of supermassive black holes with both the velocity dispersion and the mass of the central stellar cusp of their host galaxies. This implies that galaxies co-evolve with their central black holes, potentially through the feedback from actively accreting supermassive black holes (AGN). We use integral field spectroscopy data from the 8.2m Gemini-North telescope to investigate ionized gas outflows in luminous local (z<0.1) Type 2 AGN. Our sample of 6 galaxies was selected based on their [OIII] dust-corrected luminosity (>$10^{42}erg/s$) and signatures of outflows in the [OIII] line profile of their SDSS spectra. These are arguably the best candidates to explore AGN feedback in action since they are < 1% of a large local type 2 AGN SDSS sample selected based on their [OIII] kinematics. Expanding on previously reported results concerning the kinematic decomposition and size determination of these outflows, here we report their photoionization properties and energetics. We find strong evidence that connect the extreme kinematics of the ionized gas with AGN photoionization. The kinematic component related to the AGN-driven outflow is clearly separated from other kinematic components, such as gravitation- or stellar-driven motions, on the velocity and velocity dispersion diagram. Our spatially resolved kinematic analysis reveals that up to 90% of the mass and kinetic energy of the outflow is contained within the central kiloparcec of the galaxy. The total mass and kinetic energy of the outflow correlate well with the AGN bolometric luminosity, resulting in energy conversion efficiencies between 0.01% and 1%. Intriguingly, we detect ubiquitous signs of ongoing circumnuclear star formation. Their small size, the centrally contained mass and energy, and the universally detected circumnuclear star formation cast doubts on the potency of these AGN-driven outflows as agents of negative feedback.