• Journal of Power Electronics
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• v.18 no.2
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.83-90
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• 2008

Taekwondo is a martial art form and sport that uses the hands and foot for attack and defense. Taekwondo basic motion is composed of the breaking, competition and poomsea motion. In the side kick among the competition motion, the impact force is larger than other kinds of kicks. The side kick with the front foot can be made in two steps. In the first step, the front foot is stretched forward from back stance free-fighting position. For the second step, the rear foot is followed simultaneously. Then, the kick is executed while entire body weight rests on the rear foot. In this paper, impact analysis of the human model for hitting posture is carried out. The ADAMS/LifeMOD is used in hitting modeling and simulation. The simulation model creates the human model to hit the opponent. As the results, the dynamic analysis of human muscle were presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.49-56
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• 2006

The bi-directional converter interfaces the low voltage battery to the inverter do link of FC generation system. When power flows from the low voltage side(battery: 48[V]) to the high voltage side(dc link: 380[V]), the circuit works in discharge mode (boost) to power the high voltage side load; otherwise, it works in charge mode (buck) to charge the low voltage side battery. In this paper, the 1.5[kW] active clamp current-fed full bridge converter employing MOSFETs is operated to discharge the battery whereas a voltage-fed half bridge converter employing IGBTs is operated to charge the battery.

• PNF and Movement
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• v.16 no.3
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• pp.355-363
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• 2018

Purpose: The purpose of this study was to obtain detailed and quantified data concerning the effects of plantarflexor muscle fatigue induced in the non-paretic side on the spatial and temporal gait parameters of the bilateral lower extremities during walking in stroke patients. Methods: This study was conducted on 20 patients with chronic stroke. The load contraction fatigue test was applied to induce muscle fatigue in the non-paretic plantarflexor muscle. Step length, stride length, double support, gait velocity and cadence, and functional ambulatory profile (FAP) score in the bilateral lower extremities were measured using a gait analysis system in order to investigate changes in temporal and spatial gait parameters caused by muscle fatigue on the non-paretic side. The statistical significance of the results was evaluated using a paired t-test. Results: A review of the results for gait parameters revealed a significant increase in double support (p<0.05) and a significant decrease in step length, stride length, gait velocity and cadence, and FAP score (p<0.05). Conclusion: These results indicate that the muscle fatigue in the non-paretic side of the stroke patients also affected the paretic side, which led to a decrease in gait functions. This implies a necessity to perform exercise or training programs in a range of clinical aspects not causing muscle fatigue.

• 전기의세계
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• v.30 no.1
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• pp.41-46
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• 1981

In the current source inverters (CSI), which are widely used recently in many applications, in order to reduce the harmonic contents in the output line current, twelve-step waveform is synthesized usually by a phase-shifted addition of the output currents of two single CSI's. In this paper a new method of synthesis of the 12-step current waveform is suggested which employes a main and a new auxiliary inverters having lower capacity, and thus is economically advantageous over the conventional scheme. DC-side commutation and energy rebond circuit as described in Part I are also employed in this proposed twelve-step CIS for effective commutation and high reliability. Experimental results are also given in oscillgrams.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.83-91
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• 1998

Fiber Bragg grating which has a blazed ang1e to the plane of incident wave generates a side-mode as well as main-mode. The side-mode has an identical characteristics with a long period grating that couples with a cladding mode, so rejects the special wavelength. We experimented on the side-mode characteristics with two fibers which Ge doped depressed index fiber and very high photosensitive H$_2$ loaded step index fiber according to the tilted angle. Also, using a phase mask equipped with rotation plate which has 0.02$^{\circ}$ resolution, we can control the bandwidth and the peak value of a total loss spectrum by aligned tilted grating in a fiber and using this, tried to compose the ASE band rejection filter of the Erbium doped fiber amplifier.

• Journal of the Korean Society of Physical Medicine
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• v.19 no.3
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• pp.91-101
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• 2024

PURPOSE: This study examined the effects of balance exercises accompanied by ankle fixation on the healthy side on the balance control ability and gait of patients with subacute stroke. METHODS: The study was conducted on 23 patients with subacute stroke. Eleven people were assigned randomly to the experimental group who performed balance exercises with ankle fixation on the healthy side, and 12 were assigned to the control group who performed balance exercises without ankle fixation. The intervention was conducted for 30 minutes three times a week for four weeks. The Berg Balance Scale, a weight-bearing ratio measurement, was performed to evaluate the balance ability before and after intervention. The gait symmetry, walking speed, cadence, step length, and 10-meter walk test were conducted to evaluate the walking ability. RESULTS: A significant difference in the Berg Balance Scale was observed between before and after the intervention in the experimental group. A comparison of the two groups also revealed a significant difference. Significant differences in the gait symmetry, walking speed, and step length measurements were observed before and after the intervention in the experimental group, and significant differences in the gait symmetry and step length measurements were observed between the two groups. CONCLUSION: Through this study, balance exercises with the healthy side ankle fixed showed qualitative improvement in the balance and walking ability, suggesting future directions for the rehabilitation treatment of stroke patients.

• Journal of Industrial Technology
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• v.19
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• pp.59-65
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• 1999

This study is to analyze turbulent flow over a backward-facing step in a rectangular duct. The side wall effects on the internal flow were determined by varying the aspect ratio(defined as the step span-to-height ratio) from 1 to 20. In the flow behind a backward-facing step, separation, recirculation and redeveloping is occurred frequently. These phenomena appear in a particular variation by varying the aspect ratio. The results show that the aspect ratio has an influence on the velocity and reattachment length. When the AR is increased, the reattachment length is increased. For 6 over aspect ration, the rate of increase is decreased. The length of recirculation in the upper corner is increased, as the increase of aspect ration. It's width is not changed in the variation of aspect ration. The transverse, streamwise and spanwise velocities were decreased along the flow down stream of the step.

• Journal of Korean Medicine Rehabilitation
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• v.18 no.3
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• pp.147-156
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• 2008

Objectives : Oriental Medicine Music Therapy is a new way of treating and preventing various diseases and promoting health by means of music specially picked and designed to produce Qi(氣) fitting to an individual person in the areas of the structure of human body, physiological function, pathological change, diagnosis and treatment. Therefore, it can facilitate the efficiency of the treatment much better and faster than only with herb or acupuncture. Equilibrium between body and mind is its originality. Methods : A 38-year old man came to hospital suffering from left side weakness, dysarthria because of cerebral infarction. After one week's medication in the part of neurology, he was sent to the oriental medicine music therapy center, and he took ten times' medical treatments once a day. Before and after the treatments, implementing 'Ink foot print analysis', as for the movement capacity and walking of left side weakness, these results are acquired. Results and Conclusions : 1. Before the oriental medicine music therapy, except the acceleration and deceleration section, within three meters, a right foot's step was measured 30.55 cm and a left foot was measured 15.2 cm, and the step distance was 15.2 cm. After the 10 times treatments, the right foot's step was 112.6 cm, the left foot's step was 113 cm, and the step distance improved to 51.8 cm. 2. The normal person's average step is about 38 cm, and it could be decreased owing to a decreptitude, pain, fatigue, and the weakness of the legs. In spite of all, from the increased 50 cm step measurement with the patient's body condition, it means that his movement capacity is recovered. 3. In the measurement of walking time, before 10 times treatments, it took 46.35 seconds within 6M, but after the treatments, it increased to 7.47 seconds as same as a normal person's walking speed. 4. In insomnia, and the abnormality of a facial muscle, it shows lots of improvement, and even the accuracy of a pronunciation, but despite of the 10 times treatments, the 'ㄹ(r)' sound placed under a vowel is unclear. 5. Before the 10 times' treatments, he can move the left side shoulder with pain and cannot move below the left elbow. After the treatments, the pain was disappeared, and he was able to move over 60 cm without pain. And improving of the movement of fingers, he can beat over 8 times with a drumstick.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.68-75
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• 2002

The dynamic behaviors of the single vortex and flame-vortex interaction in a $CH_4/Air$ diffusion flame with addition of $CO_2$ were investigated numerically. The numerical method was based on a predictor-corrector for low Mach number flow. A two-step global reaction mechanism was adopted as a combustion model. Through comparison of results by effect of $CO_2$ added either on the fuel or oxidizer side, it was found that the growth of single vortex and entrainment of surrounding fluid by $CO_2$addition on the fuel side are larger than those by $CO_2$ addition on oxidizer side. Also, when $CO_2$ is added on fuel side, flame-vortex interaction becomes more significant than on air side.