• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.9-16
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• 2011

The purpose of this study is to analyze the effects of both various shoe types and bare feet on ground reaction force while walking. Ten first-year female university students were selected. A force platform(Kistler, Germany) was used to measure ground reaction force. Six types of shoe were tested: flip flops, canvas shoes, running shoes, elevated forefoot walking shoes, elevated midfoot walking shoes, and five-toed shoes. The control group was barefooted. Only vertical passive/active ground reaction force variables were analyzed. The statistical analysis was carried out using the SAS 9.1.2 package, specifically ANOVA, and Tukey for the post hoc. The five-toed shoe had the highest maximum passive force value; while the running shoe had the lowest. The first active loading rate for running shoes was the highest; meanwhile, bare feet, the five-toed shoe, and the elevated fore foot walking shoe was the lowest. Although barefoot movement or movement in five toed shoes increases impact, it also allows for full movement of the foot. This in turn allows the foot arch to work properly, fully flexing along three arches(transverse, lateral, medial), facilitating braking force and initiating forward movement as the tendons, ligaments, and muscles of the arch flex back into shape. In contrast movement in padded shoes have a tendency to pound their feet into the ground. This pounding action can result in greater foot instability, which would account for the higher loading rates for the first active peak for padded shoes.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.115-121
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• 2011

This study was to investigate the change of muscle fatigue through maximum contraction during flexion and extension of knee joint before and after the isometric trunk exercise was implemented on elderly Hansen's disease. 18 subjects exercised for 60 minutes twice a week for 12 weeks. The subjects were divided into normal sensory group, group with sensory loss in left sole, group with sensory loss in right sole, and group with sensory loss in both soles, according to the sensory condition on their soles. We obtained following results. Muscle fatigue in normal sensory group, there were significant differences in left right hamstring, left rectus femoris(p<.05), in group with sensory loss in left sole, there were significant differences in left right hamstring(p<.05), in group with sensory loss in right sole, there were significant differences in left right hamstring, right rectus femoris and group with sensory loss in both sole, there were significant differences in right hamstring(p<.05). The differences of muscle fatigue according to the sensory condition on their soles, there were significant differences in left hamstring between normal sensory group and group with sensory loss in both sole(p<.05).

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.85-95
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• 2011

Three-dimensional(3D) motion analysis is a useful tool for analyzing sports performance. During the last few decades, advances in motion analysis equipment have enabled us to perform more and more complicated biomechanical analyses. Nevertheless, considering the complexity of biomechanical models and the amount of data recorded from the motion analysis system, subsequent processing of these data is required for event-specific motion analysis. The purpose of this study was to develop a basic golf swing analysis algorithm using a state-of-the-art VICON motion analysis system. The algorithm was developed to facilitate golf swing analysis, with special emphasis on 3D motion analysis and high-speed motion capture, which are not easily available from typical video camera systems. Furthermore, the developed algorithm generates golf swing-specific kinematic and kinetic variables that can easily be used by golfers and coaches who do not have advanced biomechanical knowledge. We provide a basic algorithm to convert massive and complicated VICON data to common golf swing-related variables. Future development is necessary for more practical and efficient golf swing analysis.

• Korean Journal of Applied Biomechanics
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• v.21 no.1
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• pp.57-65
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• 2011

This research was conducted to biomechanically analyze Tippelt motion in parallel bars, and establish technical understanding. To achieve that goal, the performances of the Tippelt acts carried out by five world top-class national gymnasts in the parallel bars 3-dimensional cinematographic analysis and EMG analysis were conducted and following conclusion were obtained. The Tippelt motions of excellent national gymnasts perform tap motion through the down swing of a large circular movements, and perform kick-out motion rapidly extending shoulder joint angle and hip joint angle with the trunk in a position close to perpendicular position at the vertical downwardness of the grasping the bars. At this time, if handstand starting the movement is too delayed or rapidly down swung, it was shown that from the initial falling, unnecessary muscular power was wasted in trapezius, anterior deltoid, erector spinae, latissimus dorsi, upper rectus abdominis, lower rectus abdominis. The muscular parts in tap motion generating muscle action potential were pectoralis major, rectus femoris, upper rectus abdominis, lower rectus abdominis, and those in kick-out motion were upper rectus abdominis, lower rectus abdominis, trapezius and anterior deltoid.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.345-353
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• 2010

The purpose of this study was to compare and biomechanical evaluate the effects of three varying functional insoles on the kinematics of the lower extremities and foot pressure distribution during gait. For this 12 subjects participated in this study and each worn the 3 functional insoles during gait which kinematics, kinetics, electromyography and foot pressures were recorded. The function on the first insole was to absorb shock and increase the dynamic stability, the second was a gel type to absorb shock, and the third was to massage the center regions of the foot sole. the results were as follows; the first insole reduced the joints range of motion and reduced muscular fatigue, the second insole reduce the maximum, total and average foot pressures. Finally, the third insole produced larger values for the contact times and contact area.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.327-336
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• 2010

The purpose of this study was to analyze muscle activities on functional insole with diet effect. Originally, ten healthy female subjects with an average age of 23.2 year(S.D=1.1), weight of 49.7 kg(S.D=4.9), height of 163.2 cm(S.D=3.5) and a shoe size of 237.5 cm(S.D=4.9) were participated in this experiment. Ten healthy females walked on a treadmill(speed=about 4.2 km/h) wearing two different insole types. Muscle activities data was collected using the EMG operating system. The surface EMG signal for tibialis anterior(TA), gastrocnemius(GA), vatus lateralis(VL) and biceps femoris(BF) were acquired at the RMS(10 Hz, 350 Hz) using Noraxon Telemyo DTS system(Noraxon inc, USA). This study processed the data using the Windows SPSS ver.17.0 to get an independent t-test, with the setting, p<.05. Analysis of muscle activity were measured and calculated during walking. The results are as follow: Functional insole wearing were increased muscle activities significantly from Tibialis anterior(TA) during total gait cycle. Normal distribution was demonstrated in total step of stances period. One foot standing position showed decreased muscle activity. Two foot standing position was demonstrated with gastrocnemius and biceps femoris. As a result of the analysis, Functional insole will inerease the diet effect in the use of four muscle groups.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.319-325
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• 2010

The purpose of this research was to investigate the differences in the ski carving turn motion according to level of expertise. The posture and movement of 6 skiers nearby the fall-line was evaluated with a biomechanical approach focusing the rotational mechanics. The slope was at an angle of $9^{\circ}$ and the following variables were measured and calculated: tangential velocity, change of COM height after passing fall-line, width between feet, angle between upper body and thigh, trunk angle, average radius of curvature and average centripetal force. The expert skiers minimized their center of mass height movement and maintained the width of between their feet after the passing the fall-line in comparison with the beginners and intermediate skiers. The experts restrained themselves from pushing their upper body downward after the turn to maximize the centripetal force. The experts in comparison with the beginners and intermediate skiers during the turn didn't have to reduce their radius of curvature to maintain a high centripetal force. It was concluded, that the most important factor affecting the centripetal force, was for the beginners and intermediate skiers, to minimize their movement while using the appropriate amount of edging.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.311-318
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• 2010

This study examined the double piked dismount among the landing techniques of parallel bars based on three-dimensional motion analysis. Four male national gymnasts were the subjects. This study was performed to provide quantitative data highlighting players strengths and weaknesses to enable more stable landing technique. The variables analyzed were the position and velocity of center of gravity(CG) and angles of shoulder joints, hip joints, and trunk. The results are as follows: S1 secured the height of flight with fast vertical rise. After the easy spin in the air, he conducted a stable landing maintaining a proper hip joints angle. S2, S3, and S4, however, began the backward somersault already before leaving the bars, so they moved backward greatly making it more difficult to achieve a higher flight path. As a result, they couldn't control the velocity of their backward movement at landing. For a stable landing, they have to maintain the negative shoulder angle when rising, minimize both antero-posterioror side-to-side movements by doing a strong tap using hip joints, to secure the height of flight before the somersault. Results also show that at the descent, they should conduct rapid spinning by increasing their shoulder and hip joints to the maximum while controlling their velocity.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.303-310
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• 2010

The purpose of this study was (a)to compare electromyographic (EMG) activities and physiological variables on the development of fatigue induced by ergometer test, (b)to determine investigate the differences in the stage of fatigue between the electromyographic characteristics and physiological variables. Nine male university students who have no musculoskeletal disorder were recruited as the subjects. The electromyographic characteristics(peak IEMG, average IEMG, median frequency, mean edge frequency) and physiological variables(HR, RPE, blood lactate) were determined for each stage(15, 30, 45, 60 minutes, all out). For each dependent variable, one-way analysis of variance(ANOVA) with repeated measures and correlation analysis were performed to test if significant difference existed(p<.05). The results showed that peak IEMG, average IEMG from low extremity and physiological variables were significantly increased during the all-out stage. EMG parameters in VL, VM show significantly correlation with physiological variables during whole stages. This indicated that IEMG values may be proper parameters to determine muscle fatigue rather than physiological variables.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.293-301
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• 2010

The purpose of this study was to investigate the kinematic difference between skilled and less skilled group for the forward walk at dance sports rumba. Six female players(skilled group: 3, less skilled group: 3) were participated as the subjects. To obtain the three-dimensional location coordinates in the joints and segments, it shot with 100Hz/s using 8 video cameras. Step length, shoulder rotation angle, orientation angle and angular velocity of pelvis were analyzed for each trail. The skilled group showed a bigger movement than the less skilled group at the shoulder rotation angle and ROM. The skilled group showed a bigger movement than the less skilled group at the up/down obliquity and internal/external rotation movement for pelvis. And the skilled group showed a bigger movement than the less skilled group at Maximum angle (down obliquity) of P2 and Maximum angle (up obliquity) of P3 to pelvis ROM. The skilled group showed a faster angular velocity than the less skilled group at P2 (+ direction, posterior) of anterior & posterior tilt, P2 & P3 (- direction, up) of up & down obliquity, and P2 (+ direction, external) of internal & external rotation.