• Title/Summary/Keyword: Motor recovery

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A Study on the Dew Condensation According to the Operational Conditions of a Heat-Recovery Ventilator (전열교환 환기시스템의 운전 상태에 따른 결로 발생에 관한 연구)

  • Jeon, Byung-Heon;Kim, Jong-Won;Lee, Seung-Kap;Lee, Young-Ju;Ahn, Young-Chull
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.10
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    • pp.529-533
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    • 2013
  • Heat-recovery ventilators are being adopted in most newly built apartment houses for energy reduction and indoor environment improvement. In winter, however, the dew condensation resulting from the difference between the indoor and outdoor temperatures may reduce the ventilator's performance and threaten the health of indoor residents. This study analyzes the occurrence of dew condensation according to the ventilator's operational conditions and the changes of temperature and products. The experimental results show that condensations is formed at $26^{\circ}C$ and 60%R.H, which is an unfavorable climatic condition, and when the damper is not closed tightly. Therefore it is important to ensure damper performance to prevent back flow.

Surge Characteristics Analysis of Three-phase Virtual Chopping at Vacuum Circuit Breaker (진공차단기 3상 동시 차단시의 서지 특성 분석)

  • Kim, Jong-Gyeum
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.9
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    • pp.1159-1164
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    • 2018
  • Vacuum circuit breakers(VCB) are widely used for current interruption of high-voltage inductive loads such as induction motors. This VCB can be chopped off before the current zero due to its high arc-extinguishing capability. One of the outstanding features of VCB is that it can cut off high frequency re-ignition current more than other circuit breakers. If the transient recovery voltage generated in the arc extinguishing is higher than the dielectric strength of the circuit breaker, a re-ignition phenomenon occurs. The surge voltage of the re-ignition is very high in magnitude and the steepness of the waveform is so severe that it can act as a high electrical stress on the winding. If the high frequency current of one phase affects the other two phases when the re-ignition occurs, it may cause a high surge voltage due to the virtual current chopping. If the magnitude of the voltage allowed in the motor winding is high or the waveform level is too severe, it may lead to insulation breakdown. Therefore, it is necessary to reduce the voltage to within a certain range. In this study, we briefly explain the various phenomena at the time of interruption, analyzed the magnitude of the dielectric strength and the transient recovery voltage at the simultaneous three-phase interruption that can give the greatest influence to the inductive load, proposed a method to reduce the impact.

The study of paralytic side functional recovery on hemiplegia (편마비 환자의 환측 기능회복을 위한 연구)

  • Kim, Chi-Hyok;Cho, Young-Ha;Kim, Yong-Kwon
    • Journal of Korean Physical Therapy Science
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    • v.9 no.2
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    • pp.7-16
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    • 2002
  • This study was conducted to assess the changes in the functional levels of affected upper extremities after treating hemiplegic patients by applying constraint-induced movement therapy(CIMT). The subjects were selected from 20 hemiplegic patients with scores of 25 or more in Mini Mental State Examination(MMSE-k), transferred to the departments of physical therapy in two university hospitals in Busan from December, 2001 to march, 2002, and were divided into two groups. Eleven subjects with fixing unaffected arms by CIMT were assigned to the experimental patient group and the other 9 patients to control group without fixing unaffected arms. The function of upper arms for both groups were evaluated by using Actual Amount of Use Test(AAUT) and Motor Active Log(MAL) before and after physical therapy. The malts were as follows: The recovery rates of upper extremity by AOU(Activity of Use) and QOM(Quality of Movement) were 23.9% and 27.3% for CIMT treated group, and by 8.3% and 4.6% for the control group on the average, respectively, in AAUT after physical therapy, showing statistically significant differences between two groups. And in MAL, the average recovery rates were 27.3% by AOU and 22.6% by QOM for CIMT treated group while 3.1% by both AOU and QOM for the control group, and were significantly different between twogroups.

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Economic Analysis of High-Efficiency Production Facilities using Capital Recovery Factor (자본회수계수를 고려한 고효율 생산설비의 경제성분석)

  • Park, Hyung-Joon;Chung, Chcn-Soo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.7
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    • pp.117-123
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    • 2007
  • This paper is about the economic analysis of the replacement of electric facilities in the production facilities. As the interest of energy is increasing, the efficiency of facilities become more important. So, in this paper, we diagnosed facilities, especially electric motors, in the plant and calculated the operating efficiency, power loss with the load factor. And when we replace these facilities into high-efficiency motors, we also calculated new energy efficiency, energy loss and economic analysis through capital recovery factor. As a result, we economically proved that using high-efficiency motor is more beneficial than using non-high-efficiency motors in the model process.

The Study of Behavior and Histological Change on Treadmill Exercise Intensity after Spinal Cord Injury in Rats (트레드밀 강도에 따른 운동이 척수손상 흰쥐의 행동학적 변화와 조직학적 변화에 관한 연구)

  • Kim, Young-Eok
    • Journal of the Korean Academy of Clinical Electrophysiology
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    • v.6 no.1
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    • pp.1-15
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    • 2008
  • This study was designed to investigate the effect of treadmill exercise of low-intensity and high-intensity on the functional recovery and histological change in spinal cord injury rats. Sprague-Dawley rats were experimented(n=15) for this research. Spinal cord injury was induced by the NYU drop impacter device after laminectomy. After operation, rats were test at modified Tarlov scale at 3 days, and divided into the control group(n=5), experimental group I(n=5, low-intensity treadmill) and experimental group II(n=5, high-intensity treadmill). The rats were disciplined from 7 day through 21 day. Functional recovery was evaluated by the BBB scales and the Grid Walk test for the progressive locomotor recovery at 3, 7, 14, 21 days. Histopathological studies for the muscle in order to observation the change of damage and size of the organized surface which is visible visually it executed hematoxylin & eosin stain. According to the result of 4 weeks of treadmill exercise, group II showed improvement than group I of motor behavior after spinal cord injury.

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A Study on the Performance Prediction of Paper Heat Exchanger for Exhaust Heat Recovery (배기열 회수용 종이 열교환기의 성능예측에 관한 연구)

  • Yoon, Seong-Yeon;Kim, Jin-Hyuck;Chung, Min-Ho;Jie, Myoung-Seok
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.6
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    • pp.372-380
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    • 2008
  • In order to control indoor air quality and save energy, it is needed to install a suitable ventilation system equipped with heat exchanger for heat recovery. Paper heat exchanger can recover $50{\sim}70%$ of the enthalpy difference between supply and exhaust air. The purpose of this research is to obtain the experimental correlations for the friction factor, heat transfer coefficient, mass transfer coefficient and permeance of paper heat exchanger, which can be used to predict the performance of the paper heat exchanger. Pressure drops at various velocities, and sensible and latent heat transfer rates at various dry-bulb temperatures, relative humidities and specific humidities are measured to derive experimental correlations. The results of prediction using correlations show fairly good agreement with the experimental data obtained in the actual operating conditions.

Development of Wireless Neuro-Modulation System for Stroke Recovery Using ZigBee Technology (ZigBee를 이용한 뇌졸중 치료용 무선 전기 자극기 개발)

  • Kim, G.H.;Ryu, M.H.;Shin, Y.I.;Kim, H.I.;Kim, N.G.;Yang, Y.S.
    • Journal of Biomedical Engineering Research
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    • v.28 no.1
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    • pp.153-161
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    • 2007
  • Stroke is the second most significant disease leading to death in Korea. The conventional therapeutic approach is mainly based on physical training, however, it usually provides the limited degree of recovery of the normal brain function. The electric stimulation therapy is a novel and candidate approach with high potential for stroke recovery. The feasibility was validated by preliminary rat experiments in which the motor function was recovered up to 80% of the normal performance level. It is thought to improve the neural plasticity of the nerve tissues around the diseased area in the stroked brain. However, there are not so much research achievements in the electric stimulation for stroke recovery as for the Parkinson's disease or Epilepsy. This study aims at the developments of a wireless variable pulse generator using ZigBee communication for future implantation into human brain. ZigBee is widely used in wireless personal area network (WPAN) and home network applications due to its low power consumption and simplicity. The developed wireless pulse generator controlled by ZigBee can generate various electric stimulations without any distortion. The electric stimulation includes monophasic and biphasic pulse with the variation of shape parameters, which can affect the level of recovery. The developed system can be used for the telerehabilitation of stroke patient by remote control of brain stimulation via ZigBee and internet. Furthermore, the ZigBee connection used in this study provides the potential neural signal transmission method for the Brain-Machine Interface (BMI).

Effects of Robot-assisted Therapy on Lower Limb in Patients with Subacute Stroke (아급성기 뇌졸중 환자에서의 로봇 보조 보행훈련 효과)

  • Kim, Ji Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.459-466
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    • 2016
  • This study examined the effects of robot-assisted therapy on the motor and functional recovery of the lower limbs in 53 subacute stroke patients. Robot-assisted therapy was performed using Lokomat? (Hocoma AG, Zurich, Switzerland) for thirty minutes per day, five times a week for four weeks. The outcome measures used were the Fugl-Meyer assessment, Motricity index(MI), Functional ambulation category(FAC), Berg balance scale(BBS) for gait function and balance ability, 10m walking test, K-Modified Barthel Index(K-MBI) for the activities of daily living and Mini mental state examination (MMSE), and Beck's depression inventory(BDI) for depression. All patients recruited underwent these evaluations before and after the four week robot-assisted therapy. For the evaluation, the somatosensory evoked potentials were used to assess the functional recovery. Robot-assisted therapy on the lower limb after subacute stroke showed improvement in motor strength, gait function, and the activities of daily living. All changes in terms of MI, FAC, BBS, and K-MBI exhibited a statistically significant difference after the four weeks robot-assisted therapy. The somatosensory evoked potential result showed a correlation with the MI and K-MBI. Robot-assisted therapy is believed to facilitate the motor and functional recovery of the lower limb in subacute stroke patients.

Hybrid-Boost Modular Multilevel Converter-Based Medium-Voltage Multiphase Induction Motor Drive for Subsea Applications

  • Daoud, Mohamed;Elserougi, Ahmed;Massoud, Ahmed;Bojoi, Radu;Abdel-Khalik, Ayman;Ahmed, Shehab
    • Journal of Power Electronics
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    • v.19 no.3
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    • pp.714-726
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    • 2019
  • This paper proposes a hybrid-boost Modular Multilevel Converter (MMC) for the Medium-Voltage (MV) Variable Speed Drives (VSDs) employed in subsea applications, such as oil and gas recovery. In the presented architecture, a hybrid-boost MMC with a reduced number of semiconductor devices driving a multiphase Induction Machine (IM) is investigated. The stepped output voltage generated by the MMC reduces or eliminates the filtering requirements. Moreover, the boosting capability of the proposed architecture eliminates the need for bulky low-frequency transformers at the converter output terminals. A detailed illustration of the hybrid-boost MMC operation, the expected limitations/constraints, and the voltage balancing technique are presented. A simulation model of the proposed MV hybrid-boost MMC-based five-phase IM drive has been built to investigate the system performance. Finally, a downscaled prototype has been constructed for experimental verification.

A Novel Technique for Tuning PI-Controllers in Induction Motor Drive Systems for Electric Vehicle Applications

  • Elwer Ayman Saber
    • Journal of Power Electronics
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    • v.6 no.4
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    • pp.322-329
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    • 2006
  • In the last decade, the increasing restrictions imposed on the exhaust emissions from internal combustion engines and traffic limitations have increased the development of electrical propulsion systems for automotive applications. The goal of electrical and hybrid vehicles is the reduction of global emissions, which in turn leads to a decrease in fuel resource exploitation. This paper presents a novel approach for control of Induction Motors (IM) using the Particle Swarm Optimization (PSO) algorithm to optimize the parameters of the Proportional Integral Controller (PI-Controller). The overall system is simulated under various operating conditions. The use of PSO as an optimization algorithm makes the drive robust and insensitive to load variation with faster dynamic response and higher accuracy. The system is tested under variable operating conditions. The simulation results show a positive dynamic response with fast recovery time.