• Journal of the Korean Academy of Clinical Electrophysiology
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• v.6 no.1
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• pp.17-30
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• 2008

This study was investigated the effects of pain and functional recovery when low frequency electrical stimulation and aquatic exercise applied to sciatic nerve injured rats. The rats were assigned into four groups; Group I(n=20, control group), Group II(n=20, low frequency electrical stimulation group), Group III(n=20, aquatic exercise group), Group (n=20, applied low frequency electrical stimulation and aquaatic exercise group). Each IV group measured hot plate examination, sciatic nerve functional index(SFI), c-fos.. In hot plate examination, group II, IV showed effect than group Iat 14 days after injured(p<0.01) and group III, Ⅳ showed effect than group I at 21, 28 days after in-jured(p<0.01, p<0.001). In SFI, group II, III, IV showed effect II, III, IV than group I and group IV showed effect than group II at 14, 21 days after injured(p<0.001). group II, III, IV showed effect than group I at 28 days after injured(II = p<0.01, III and IV = p<0.001). Effects of pain and function recovery when low frequency electrical stimulation and aqua-exercise applied to sciatic nerve injured rats, group Ⅳ were most effected to sciatic nerve injured rats. As well as group II and III were effected to sciatic nerve injured rats.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.197-201
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• 2007

The reattachment characteristics of propane lifted flames in laminar coflow jets influenced by AC electric fields have been investigated experimentally in low AC frequency range. The reattachment velocity and height have been measured by varying the applied AC voltage and frequency. The results showed that the reattachment of lifted flame occurred at relatively higher jet velocity with AC electric fields, comparing to that without having AC electric fields. The effect of AC electric fields became more effective at higher voltage and lower frequency in the AC frequency range larger than 30 Hz. However, in the low frequency range below 30 Hz, the reattachment velocity decreased with decreasing frequency. Consequently, there existed a transition regime, for the frequency smaller than about 30 Hz. Also, when the AC voltage was applied to the fuel nozzle at very low frequency, the reattachment process exhibited an oscillatory behavior, synchronized with the applied AC frequency.

• Journal of Biosystems Engineering
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• v.16 no.3
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• pp.263-271
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• 1991

When grains is subjected to oscillating load, the dynamic viscoelastic behavior of the material will be describe the complex modulus of the material. The complex modulus and therefore the storage modulus, the loss modulus, and the phase angle for the sample should be obtainable with a given static viscoelastic property of the material under static load. The complex relaxation moduli of the rough rice kernel were computed from the Burger's model describing creep behavior of the material which were obtained in the previous study. Also, the effects of cyclic load and moisture content of grain on the dynamic viscoelastic behavior of the samples were analized. The storage modulus of the rough rice kernel slightly increased with the frequency applied but at above the frequency of 0.1 Hz it was nearly constant with the frequency, and the loss modulus of the sample very rapidly decreased with increase in the frequency on those frequency ranges. It was shown that the storage modulus and the loss modulus of the sample increased with decrease in grain moisture content. Effect of grain moisture content on the storage modulus of the sample was highly significant than effect of the frequency applied, but effect of the frequency on the loss modulus of the sample was more significant than effect of grain moisture content.

• The Korean Journal of Pain
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• v.2 no.2
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• pp.145-154
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• 1989

Pain is a common and important clinical symptom, and treatments aimed at relieving pain have a central position in medical practice. Recently Transcutaneous Electrical Nerve Stimulation (TENS) has been effectively used to control acute and chronic conditions that produce pain. But the mechanism of analgesia resulting from TENS remains obscure. In order to investigate the analgesic effect of TENS and it's action mechanism, TENS was applied in 40 rabbits with different frequencies, low frequency (2Hz) and high frequency (100Hz), for 20 minutes. And the pain threshold was measured by the temperature before and after stimulation, and an attempt was made to antagonize the stimulation effect with naloxone pretreatment (0.4 mg/kg) The results are as follows: 1) Both low frequency and high frequency TENS resulted in increasing the pain threshold significantly (Both p<0.01). 2) Naloxone pretreatment could antagonize the effect of increasing the pain threshold with low frequency TENS significantly (p<0.01), but not with high frequency TENS. Plasma beta-endorphin was measured by radioimmunoassay using an Beta-Endorphin Kit (Immunonuclear Corporation, Stillwater, Minnesota, USA) and Automatic Gamma Scintillation Counter (Micromedic System 4/2000) before and after stimulation. An attempt was made to reverse the stimulation effect with naloxone pretreatment (0.4 mg/kg). The results are as follows: 1) Low frequency TENS resulted in increasing the level of plasma beta.endorphin significantly (p<0.01), but high frequency TENS did not. 2) Naloxone pretreatment could reverse the effect of increasing the plasma beta-endorphin level with low frequency TENS significantly (p<0.01).

• Proceedings of the KSPS conference
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• 2002.11a
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• pp.93-96
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• 2002

This research studied the correlation of word frequency effect in Korean corpus. Experiment 1 showed that word frequency of each other corpus was significant correlated. Experiment 2 showed significant correlation between word frequency of each corpus and lexical decision time of participants. These results support that 4 corpus in this research should have stability to word frequency effect of participants

• Journal of Drive and Control
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• v.18 no.2
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• pp.9-19
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• 2021

The spool displacement signal of a directional control valve, including the servo valve, can be considered as the standard signal to measure dynamic characteristics. When the spool displacement signal is not available, the velocity signal of a metering cylinder piston can be used. In this study, the frequency response characteristics of the metering cylinder are investigated for the spool displacement input. The transfer functions of the servo valve-metering system are derived taking into consideration the oil inertia effect in the transmission lines. The theoretical results of the transfer functions are verified through computer simulations and experiments. The oil inertia effect in the transmission lines was found to have a very significant effect on the bandwidth frequency of the servo valve-metering cylinder system. In order to more precisely measure the dynamic characteristics of a servo valve, the metering cylinder should be set up to minimize the oil inertia effect by increasing the inner diameters of the transmission lines or shortening their lengths.

• The Journal of Korean Medicine
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• v.33 no.3
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• pp.20-32
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• 2012

Objectives: The purpose of this study was to investigate the effect of acupuncture and electro-acupuncture (EA) of low and high frequencies at Haegye (ST41) in rats. Methods: The intestinal motility of rats was experimentally suppressed with loperamide. Acupuncture, low frequency EA and high frequency EA were carried out before the loperamide administration in the pre-treatment group, and after the loperamide administration in the post-treatment group. The rats were fed charcoal and the travel rate of charcoal in the gastrointestinal track was measured to analyze the effect of acupuncture, low frequency EA and high frequency EA on the intestinal hypo-motility. Results: 1. None of acupuncture, low frequency EA or high frequency EA at ST41 showed significant influences on intestinal motility of rats in normal status. 2. Pre-treatment with acupuncture at ST41 showed no significant effect on the intestinal hypo-motility induced by loperamide in rats. 3. Pre-treatment with low frequency EA and high frequency EA at ST41 significantly reduced the suppression of intestinal motility by loperamide in rats. 4. Post-treatment of acupuncture, low frequency EA and high frequency EA at ST41 had no significant influences on the intestinal hypo-motility induced by loperamide in rats. Conclusions: These results suggest that low and high frequency EA at ST41 may be effective to prevent gastric disorders such as intestinal hypo-motility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1247-1251
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• 2016

This study aims to investigate the effect of sampling frequency to the time domain and frequency domain analysis of pulse rate variability (PRV). Typical time domain variables - AVNN, SDNN, SDSD, RMSSD, NN50 count and pNN50 - and frequency domain variables - VLF, LF, HF, LF/HF, Total Power, nLF and nHF - were derived from 7 down-sampled (250 Hz, 100 Hz, 50 Hz, 25 Hz, 20 Hz, 15 Hz, 10 Hz) PRVs and compared with the result of heart rate variability of 10 kHz-sampled electrocardiogram. Result showed that every variable of time domain analysis of PRV was significant at 25 Hz or higher sampling frequency. Also, in frequency domain analysis, every variable of PRV was significant at 15 Hz or higher sampling frequency.

• Journal of Acupuncture Research
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• v.33 no.1
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• pp.9-21
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• 2016

Objectives : The aim of this study was to investigate the effect of low frequency electro-acupuncture at ST39 on intestinal motility in rats. Methods : Intestinal hypermotility and hypomotility in rats were induced by oral carbachol ingestion and loperamide injection. Rats were divided into seventeen experimental groups including the normal and holder groups. The rats were induced with intestinal hypermotility and hypomotility and divided into pre and post-treatment groups. I also carried out acupuncture (needle retention) and low frequency electro-acupuncture at ST39 or the sham point. I fed charcoal to rats after the treatment and calculated its distance travelled in the gastrointestinal tract, which was compared by groups so as to determine which treatment was more effective in increasing or decreasing intestinal motility. Results : 1. In normal rats, low frequency electro-acupuncture at ST39 showed no significant effect on intestinal motility. 2. Pre-treatment with acupuncture (needle retention) at ST39 on intestinal motility over-activated with carbachol significantly decreased intestinal motility in rats. 3. Pre-treatment with low frequency electro-acupuncture at ST39 on intestinal motility over-activated with carbachol significantly decreased intestinal motility in rats. 4. Pre-treatment with acupuncture (needle retention and low frequency electro-acupuncture) at ST39 showed no significant effect on intestinal hypomotility in rats that was induced by loperamide injection. Conclusions : These results suggest that acupuncture (needle retention) and low frequency electro-acupuncture at ST39 have preventive effects on intestinal hypermotility. Regardless of the stimulation method, ST39 showed an effect on intestinal motility. Further study is required to confirm other effects of ST39.

• The Journal of the Acoustical Society of Korea
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• v.32 no.5
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• pp.385-392
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• 2013

The sound generated from the formula 1 (F1) machine is characteristic in that the frequency felt by the listener changes drastically by the Doppler effect as the machine bypasses him. In textbooks, longitudinal Doppler effect is usually described. In this paper, we consider a more general case where the listener is away from the rectilinear path of the machine's motion. As the machine bypasses the listener, in this case, the frequency drops not abruptly but gradually, the temporal width for the frequency drop depending on the machine's speed. The frequency shift felt by the listener is analyzed as functions of time and/or machine location in our study. The machine's speed is estimated from the frequency analysis of an actual F1 sound.