• Korean Journal of Applied Biomechanics
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• v.21 no.5
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• pp.551-560
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• 2011

The purpose of this study was to perform the kinematic analyses of the men's pole vault skills in IAAF World Championships Daegu 2011. Subjects were the 1st through 8th place finishers in the pole vault. The kinematic analyses were divided into four phases: two dimensional run up analysis, and three dimensional analyses for the remaining plant, swing up, and extension phases. Run-up variables consisted of run up distance, number of steps, average step length, the ratio of step length to his height, average velocity at the final 6~11 m, approach position. Three variables were analyzed during plant: pole angle, center of gravity (COG) velocity, and takeoff angle of COG. Swing up phase variables included: pole flexion angle, COG velocity (horizontal, vertical, resultant), COG trajectory and bar approach angle of COG. Compared to the 2009 World Championships in Berlin, the average vault height, run up velocity and approach position increased. However, horizontal velocity during the last two steps of the final approach decreased dramatically compared to speeds from 1990. These results reflect the change in both technique and improved physical fitness in pole vaulters. During extension, the peak height of COG averaged 0.3m higher then COG height when the pole was released. These specific results can help coaches and athletes modify training and improve performance.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.267-276
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• 2010

The purpose of this study was to investigate the variations in gait parameters according to arm slings used in healthy adults. Twenty healthy adults (9 males, 11 females) participated in this study and walked at self-selected speeds on a GAITRite-instrumented carpet. They were randomly assigned conditions: without an arm sling, a care sling, a Harris hemi arm sling, a CVA sling, and a Rolyan humeral cuff sling. The following gait parameters were analyzed: the temporo-spatial parameters of gait velocity, swing phase, single support, cadence. In the comparison of parameters in each trial, step length was statistically significantly changed(p=.002). The right step length was significantly decreased in the Harris hemi arm sling and increased in the Rolyan humeral cuff sling when compared with no sling. This study found that several different types arm slings varied gait pattern in healthy adults.

• Korean Journal of Applied Biomechanics
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• v.24 no.3
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• pp.287-293
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• 2014

The purpose of this study was to investigate the effects of Hoehn-Yahr scale on the activation of lower-extremity muscles during walking. Electromyography (EMG) analysis was carried out on 36 patients with Parkinson's disease in the off phase of the medication cycle. We recorded EMG signals of the tibialis anterior (TA), medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus (SOL), rectus femoris (RF), vastus lateralis (VL), semitendinosus (ST) and biceps femoris (BF) using Noraxon 16 channels EMG system during walking at preferred speed. Rectified EMG signals were normalized to reference voluntary contractions (RVC) over a gait cycle at the preferred speed, allowing for an assessment of how the activity was distributed over the gait cycle. Compared to the H & Y Scale 1, H & Y Scale 3 exhibited greater activation of the vastus lateralis during mid-stance and greater activation of the medial gastrocnemius during terminal swing. Compared to the H & Y Scale 1, H & Y Scale 2 and 3 exhibited less activation of the tibialis anterior during initial swing. We conclude that the more Hoen & Yahr Scale increase, the more abnormal lower-extremity muscles activation.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.1-10
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• 2006

The purpose of this study was to identify critical parameters of a putting performance using jerk cost function. Jerk is the time rate of change of acceleration and it has been suggested that a skilled performance is characterized by decreased jerk magnitude. Four elite golfers($handicap{\leq}2$) and 4 novice golfers participated in this study for the comparison. The 3D kinematic data were collected for each subject performing 5 trials of putts for each of these distances (random order): 1m, 3m, 5m The putting stroke was divided into 3 phases such as back swing. down swing and follow-through. In this study, it was assumed that there exist smoothness difference between elite and novice golfers during putting. The distance and jerk-cost function of Putting stroke for each phase were analyzed Results showed that there was a significant difference in jerk cost function at putter toe (at media-lateral direction) and at the center of mass between two groups by increasing putting distance. From these it could be concluded that jerk can be used as a kinematic parameter for distinguishing elite and novice golfers.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.9
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• pp.64-72
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• 1998

In this paper, the design of a current integrator for low-voltage, low-power, and high frequency applications using complementary high swing cascode current-mirror is presented. The proposed integrator decreases output current errors due to non-zero input resistance and non-infinite output resistance of the simple current integrator. As a design example, the 3rd order Butterworth lowpass filter is designed by a leapfrog method. Also, we apply the predistortion design method to reduce the magnitude distortion which occurs at a cutoff frequency by the undesirable phase shift of a lossless current integrator. The designed current-mode filter is simulated and examined by SPICE using 0.8$\mu\textrm{m}$ CMOS n-well process parameters. The simulation results show 20MHz cutoff frequency and 615㎼ power dissipation with a 2V power supply. And the cutoff frequency of the filters can be easily changed by the DC bias current.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.131-136
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• 2007

In this study, we developed an active ankle-foot orthosis(AAFO) which can control dorsi/ plantar flexion of the ankle joint to prevent foot drop and toe drag during walking. 3D gait analyses were performed on five healthy subjects under three different gait conditions: the normal gait without AFO, the SAFO gait with the conventional plastic AFO, and the AAFO gait with the developed AFO. As a result, the developed AAFO preeminently induced the normal gait compared to the SAFO. Additionally, AAFO prevented foot drop by proper plantarflexion during loading response and provided enough plantarflexion moment as a driving force to walk forward by sufficient push-off during pre-swing. AAFO also could prevent toe drag by proper dorsiflexion during swing phase. These results indicate that the developed AAFO may have more clinical benefits to treat foot drop and toe drag, compared to conventional AFOs, and also may be useful in patients with other orthotic devices.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.221-235
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• 2005

The purpose of this study was to analyse badminton players' drop-shots, in order' to make players understand the principles of drop-shot motion in badminton. Three dimensional analysis was used to measure movements such as the time required per section, the change of center of gravity, joint angle and speed, and joint speed. The results of this study revealed as follows: (1) top players are faster than amateurs in the total time required per section; (2) top players moved more in the x-axis and z-axis, while amateurs moved more in the y-axis; (3) the inclination of amateurs was greater than that of top players in all phases; (4) amateurs showed larger angle on the shoulder joints than top players in the first phase, while top players showed larger angle on the shoulder joint than amateurs in the second and third phase. Amateurs' angle was larger on angle joint in the first phase than top players' ones, while top players' angle was larger in the third phase than amateurs; (5) the speed of racket head of top players was faster than that of amateurs; and the velocity of the center of gravity of amateurs was greater than that of the top players. The findings of this study were that gravity decreases during impact and then the velocity increases to perform the follow-through and making the swing fast by increasing the speed of the racket head is most important.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.991-996
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• 2017

Gait stability is partly characterized by an extended stance phase that comprises 60 of the gait ％ cycle. In this study, a gait pattern was employed for a crank drive system that allows for stable lower limb kinematics during stand-up cycling. A quick return mechanism was applied to the crank system to allow for a slow rotation of the crank during the stance phase and for a quick return during the swing phase. Design parameters for the quick return crank mechanism were defined, and kinematic simulations were performed to understand the behavior of the mechanism. To evaluate the design, an experimental instrument was fabricated, and the cycling motion was analyzed. The results indicated that this new drive system can stabilize the center of mass of the user. This study can contribute to the development of a stand-up bicycle that allows for more comfortable leg kinematics.

• The Journal of Korean Physical Therapy
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• v.26 no.3
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• pp.136-139
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• 2014

Purpose: The purpose of this study will demonstrate that relationship between scoliosis and gait factor and foot weight bearing in ambulation. Methods: Subjects were 40 elementary students. A normal control group consisted of a total of 20 children without any known musculoskeletal disorders and an AIS group of 20 children with mild AIS (defined by a Cobb angle between 10 and $25^{\circ}$) were recruited. Measurements were scoliometer screening test, Cobb angle, gait parameter (rate of swing/stance phase, gait velosity), foot weight bearing (entire, fore, hind). Results: Scoliometer screening test (P = 0.000) and X-ray Cobb angle (P = 0.000) significant difference of group which was significantly higher in the AIS group. Gait parameter not showed significant difference. Forefoot weight bearing was significantly higher in the AIS group than more normal group. Conclusion: It seems that the results of weight bearing analysis in ambulation may be used in modifying rehabilitation programs for individual needs of patients with idiopathic scoliosis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.437-444
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• 2015

A high output power voltage controlled oscillator (VCO) in the U-band was implemented using a 65 nm CMOS process. The proposed VCO used a transmission line to increase output voltage swing and overcome the limitations of CMOS technologies. Two varactor banks were used for fine tuning with a 5% frequency tuning range. The proposed VCO showed small variation in output voltage and operated at 51.55-54.18 GHz. The measured phase noises were -51.53 dBc/Hz, -91.84 dBc/Hz, and -101.07 dBc/Hz at offset frequencies of 10 kHz, 1 MHz, and 10 MHz, respectively, with stable output power. The chip area, including the output buffer, is $0.16{\times}0.16mm^2$ and the maximum output power was -0.11 dBm. The power consumption was 33.4 mW with a supply voltage of 1.2-V. The measured $FOM_P$ was -190.8 dBc/Hz.