• 대한의용생체공학회:의공학회지
• /
• 제28권2호
• /
• pp.212-217
• /
• 2007

As a preliminary study for the development of electrical stimulation strategy of artificial retina, we set up a method fur the reconstruction of input intensity variation from retinal ganglion cell(RGC) responses. In order to estimate light intensity variation, we used an optimal linear filter trained from given stimulus intensity variation and multiple single unit spike trains from RGCs. By applying ON/OFF stimulation(ON duration: 2 sec, OFF duration: 5 sec) repetitively, we identified three functional types of ganglion cells according to when they respond to the ON/OFF stimulus actively: ON cell, OFF cell, and ON-OFF cell. Experiments were also performed using a Gaussian random stimulus and a binary random stimulus. The input intensity was updated once every 90 msec(i. e. 11 Hz) to present the stimulus. The result of reconstructing 11 Hz Gaussian and binary random stimulus was not satisfactory and showed low correlation between the original and reconstructed stimulus. In the case of ON/OFF stimulus in which temporal variation is slow, successful reconstruction was achieved and the correlation coefficient was as high as 0.8.

• 음성과학
• /
• 제14권2호
• /
• pp.35-42
• /
• 2007

The aim of this study is to analyze the correlation between current intensity and amplitude of stimulus artifact on the cochlear implantee, and to find out basic information to check the device failure. Subjects were a prelingual child and 3 postlingual adults with more than severe hearing losses. The charge-balanced biphasic pulses were presented at stimulus rates of 11 pulses per second, each pulse width of $25{\mu}s$ with monopolar mode(MP1+2). Current intensities were delivered at 27.5, 33.7, 41.3, 50.5, 61.9, $75.8{\mu}A$. Stimulus artifacts were recorded by evoked potential system. This procedure was performed just before the initial stimulation, and then, the amplitude of stimulus artifacts were compared with each current intensity. The amplitude of stimulus artifacts was increased significantly according to the current intensity (p<0.01). The results suggest that the change of the amplitude of stimulus artifact can be used as a good cue to check the device failure in the cochlear implantee.

• 음성과학
• /
• 제12권2호
• /
• pp.81-88
• /
• 2005

Electrodermal activity(EDA) is a bio-electric signal which occurs at the skin surface during the sweating. EDA reflects the activity of the sympathetic axis of the autonomic nervous system. EDA is associated with the eccrine sweat gland at the palmar and plamar surface. This study was aimed to characterize the relationship between EDA and auditory stimulus intensities. Acoustic stimulus used in this study were 500 Hz, 1 kHz, 2 kHz of narrow band noise, which were representative of speech frequencies in audible range. Stimulus intensity between 90 and 30 dB in 10 dB within dynamic range. After deriving the minimum stimulus intensity(threshold of skin potential) which elicited skin potential, and then the latency and amplitude were derived from waveform of skin potential, each latency and amplitude were compared to stimulus intensity. The waveform of skin potential were recorded stably, and the threshold of skin potential appeared nearly the hearing threshold level of the participant. The latency was decreased and the amplitude was increased according to the increase of the stimulus intensity. These results suggest that auditory evoked skin potential can be applicable to auditory assessment and audiological diagnosis tool.

• The Journal of Korean Physical Therapy
• /
• 제22권1호
• /
• pp.61-66
• /
• 2010

Purpose: The purpose of this study was to investigate the change in sympathetic nervous system responses of healthy adult women with changes in stimulus intensity of high frequency transcutaneous electrical nerve stimulation. Methods: Twenty-four healthy subjects (women) received high frequency electrical stimulation of the forearm. The subjects were randomly assigned to one of two groups; a low intensity stimulation group (n=12) and a high intensity stimulation group (n=12). The electrode attachment was arranged on the forearm of the dominant arm and the electricity stimulus time was 20 minutes. Measured items included skin conductance, pulse rate, skin temperature, and respiration rate. Each was measured at 4 times. Results: Skin conductance and skin temperature showed significant group by time interactions, though there were no significant group and time effects. There were no significant differences according to time, group effect, and a group by time interaction in pulse and respiration rates. Conclusion: High frequency and high intensity electrical stimulation may be helpful for the improvement of sudomotor function through the activation of the sympathetic nervous system. Also, high frequency and low intensity electrical stimulation may be helpful for the reduction of sudomotor function via inhibition of the sympathetic nervous system.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권12호
• /
• pp.4513-4532
• /
• 2014

Motivated by the Weber's Law, this paper proposes an efficient and robust shape descriptor based on the perceptual stimulus model, called Weber's Law Shape Descriptor (WLSD). It is based on the theory that human perception of a pattern depends not only on the change of stimulus intensity, but also on the original stimulus intensity. Invariant to scale and rotation is the intrinsic properties of WLSD. As a global shape descriptor, WLSD has far lower computation complexity while is as discriminative as state-of-art shape descriptors. Experimental results demonstrate the strong capability of the proposed method in handling shape retrieval.

• 수산해양기술연구
• /
• 제39권2호
• /
• pp.128-133
• /
• 2003

본 연구에서는 스트로보광의 자극효과를 검토할 목적으로 스트로보광 강도에 따른 전갱이의 반응을 심박수의 변화로 조사하였다. 실험은 10$Hz$의 스트로보광강도(75 lx$\cdot$s)를 1/2, 1/5, 1/15로 빛의 세기를 감소시켜, 4단계의 강도별로 심박수를 자극 전 10분간, 자극 중 30분간, 자극 후 20분간 합계 60분간을 2시간마다 3회 연속해서 측정하였다. 그 결과, 스트로보광자극 중의 심박수 증가와 자극 종료직후에 일시적으로 현저한 심박수 감소가 있었다. 스트로보광 자극효과는 자극강도의 감광에 따라 감소하였다. 반복실험에 의한 자극효과는 75 lx$\cdot$s의 강도보다 약한 스크로보광 강도에서는 현저하게 나타나지 않았다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 춘계학술대회 논문집
• /
• pp.1301-1302
• /
• 2012

• Journal of Magnetics
• /
• 제19권1호
• /
• pp.32-36
• /
• 2014

The purpose of this study was to investigate the effect of pulsed magnetic field (PMF) and low frequency low level laser (LFLLL) stimuli on acupoint LI4 (Hegu) using photoplethysmography (PPG). Our PMF system was designed to generate maximum intensity of 0.20 T at a transition time of 0.16 ms, with pulse intervals of 1 Hz. The diode laser with wavelength of 650 nm and power of 5 mW was also employed. It was observed the change of the pulsating blood volume through measuring PPG signals from both hands. These results imply that stimulating acupoint LI4 with PMF and LFLLL improves the circulation of peripheral vascular system. In particular, PMF stimulation brings a big improvement of the blood flow even with short term stimulation of 3-4 minutes compared to LFLLL stimulus.

• Journal of Acupuncture Research
• /
• 제23권4호
• /
• pp.175-185
• /
• 2006

Objectives : This study was designed to investigate effects of electro-acupuncture's stimulated frequency, intensity, duration at 5736 on tile Small Intestine Motility in Rats. Methods The motor activity of small intestine in rats was evaluated by intestinal transportation rate. Changes in tile motility of ileum in vivo was measured at 10 minutes after electro-acupuncture. Various kinds of stimulus-frequency were used in this experiment: 2 Hz, 50 Hz, 100 Hz, 2 Hz-4 trains, 8 Hz groups treated with EA of the condition in S mA, 1 ms pulse duration, 30 minutes stimulated duration. Three different stimulus-intensity were used: 1, 5, 10 mA groups treated with EA of the condition in 2 Hz, 1 ms pulse duration, 30 minutes stimulated duration. Six different stimulus-duration were used: 10, 20, 30, 40, 50, 60 minutes groups treated with EA of the condition in 2 Hz, 5 mA, 1 ms pulse duration. Results : 2 and 100 Hz groups significantly increased the small intestine motility, but 50 Hz group did not induce a significant change. Besides, small intestine motility was significantly increased only in 5 mA intensity (5 times twitch). futhermore, at least 20 minutes EA treatment was necessary to increase the small intestine motility. Conclusion : Those basic data form this study can be applied to established the effective treatment of EA for gastrointestinal diseases in the clinical field.

• PNF and Movement
• /
• 제19권2호
• /
• pp.195-203
• /
• 2021

Purpose: Neurodynamic tests are used to examine neural tissue in patients with neuro-musculoskeletal disorders, although this has not yet been established in the intensity of nerve tension application. This study aimed to investigate the acute effects of neural stretching intensity on nerve excitability using the latency and amplitude of nerve conduction velocity test (NCV) analysis. Methods: Thirty young, healthy male and female subjects (mean age = 21.30 years) voluntarily participated in this study. Nerve excitability was assessed using the median sensory NCV test. The latency and amplitude of the NCV test were measured under four different conditions: reference phase (supra-maximal stimulus, without neural stretching), baseline phase (2/3 of the supra-maximal stimulus, without neural stretching), weak stretch phase (2/3 of the supra-maximal stimulus, with weak neural stretching), and strong stretch phase (2/3 of the supra-maximal stimulus, with strong neural stretching). Results: The NCV latency was significantly delayed after one minute of neural stretching at the baseline, weak phase, and strong phase in comparison with the reference phase. The NCV latency was significantly delayed by increasing the strength of neural stretching. Furthermore, the NCV amplitude was significantly increased at the weak and strong phases, which were under neural stretching, in comparison with the baseline phase. The NCV amplitude was significantly increased by increasing the strength of the neural stretching. Conclusion: Transient neural stretching as a neurodynamic test can increase the sensitivity of the nerve without negatively affecting the nervous system. However, based on the results of this study, strong neural stretching in the neurodynamic test may delay the transmission of nerve impulses and hypersensitivity.