• Journal of Magnetics
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• 제15권4호
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• pp.213-220
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• 2010

Since the hypothalamus immediately reacts to a nerve by processing all the information from the human body and the external stimulus being conducted, it performs a significant role in internal secretion; thus, a diverse and rapid stimulus pulse is required. By detecting Zero Detector accurately via the application of AVR on-Chip (ATMEL) using commercial electricity, chopping generates a stimulus pulse to the brain using an IGBT gate to designate a new magnetic stimulation following treatment and diagnosis. To simplify and generate a diverse range of stimuli for the brain, chopping can be used as a free magnetic stimulator. Then, commercial frequency (60Hz) is chopped precisely at the first level of the leakage transformer to deliver an appropriate stimulus pulse towards the hypothalamus when necessary. Discharge becomes stable, and the chopping frequency and duty-ratio provide variety after authorizing a high-pressure chopping voltage at the second level of the magnetic stimulator. These methods have several aims. The first is to apply a variable stimulus pulse via accurate switching frequency control by a voltaic pulse or a pulse repetition rate, according to the diagnostic purpose for a given hypothalamus. Consequently, the efficiency tends to increase. This experiment was conducted at a maximum of 210 W, a magnetic induced amplitude of 0.1~2.5 Tesla, a pulse duration of $200{\sim}350\;{\mu}s$, magnetic inducement of 5 Hz, stimulus frequency of 0.1~60 Hz, and a duration of stimulus train of 1~10 sec.

• 한국자기학회지
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• 제24권1호
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• pp.28-33
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• 2014

최대 0.27 T 세기와 0.102 ms 펄스시간을 가지는 자기장 자극시스템을 이용하여 손에 인가한 후에 생혈액 분석을 통해 말초혈관에 흐르는 적혈구의 형태학적 변화를 조사하였다. 펄스자기장 자극 전 피실험자의 적혈구는 10여개 이상씩 서로 붙어있는 연전형성(連錢形成, rouleau formation)이 일어나서 적혈구의 움직임이 느려졌으나, 손에 10분간 자기장 인가한 후에 연전형성이 되었던 적혈구가 대부분 떨어져서 독립적인 움직임을 보이면서 운동이 활발해졌다. 또한 왼쪽 손에 펄스자기장을 10분 자극한 후에 자극받지 않은 오른쪽 손에서 채혈했을 때에도 연전현상이 똑같이 개선되었다. 이는 혈류흐름에 의해 체내에 모든 적혈구의 연전현상이 개선된 것으로 판단할 수 있다.

• 대한의용생체공학회:의공학회지
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• 제17권3호
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• pp.373-378
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• 1996

In this paper, we calculated chronaxy value in order to determine the optimal conditions and stimulus pulse of information transmission. We also developed an electrical equivalent circuit of the hand including the contact part, which consists of two resistors (a contact resistor and finger resistor) and a capacitor. The minimum recoulition voltage was measured by using electrical stimulus. We found that the ranges of the above two resistances and the capacitance are 30-130k$\Omega$, 20-60k$\Omega$ and 10-30nF respectively. We found that the minimum recoulition voltage was the lowest at 100-300Hz and 10% of the duty ratio.

• Journal of Magnetics
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• 제20권2호
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• pp.114-119
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• 2015

This study explored the effect of pulsed magnetic field (PMF) stimulus on the improvement of blood stagnation by means of photoplethysmography (PPG). Our stimulus system was designed to generate PMF with a maximum intensity variation of 0.20 T at a transition time of $160{\mu}s$, with pulse intervals of 1 Hz. In order to quantitatively estimate vascular condition, indices such as blood vessel tension (BVT), stress power (SP), differential pulse wave index (DPI) and remained blood volume (RBV) were calculated from the second derivative of the PPG signal and power density spectrum (PDS). Our results showed that non-invasive PMF stimulus was effective in improving blood stagnation. Therefore, it may be concluded that appropriate PMF stimulus affects the blood circulatory system.

• The Korean Journal of Physiology and Pharmacology
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• 제19권2호
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• pp.167-175
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• 2015

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an $8{\times}8$ multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than $10{\mu}A$ and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to $500{\mu}s$($30{\mu}A$), changing the intensities (or duration) from 2 to $60{\mu}A$(60 to $1000{\mu}s$). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.429-438
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• 1994

An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate eleclromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocnemius m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher'stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical slimulator restored partially gait function in paraplegic patients.

• 대한의용생체공학회:의공학회지
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• 제10권2호
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• pp.109-111
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• 1989

An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate electromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocneminus m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical stimulator restored partially gait function in paraplegic patients.

• 한국자기학회지
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• 제21권5호
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• pp.180-184
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• 2011

자기장 자극시스템을 통하여 순간펄스 고자기장을 손바닥과 발바닥 그리고 무릎에 인가한 후 체열진단시스템을 통하여 모세혈관을 포함한 인체의 혈관 자극에 의한 혈류개선 효과를 연구하였다. 연령별, 성별 구분을 통하여 자극 후 체열진단을 통해 공통적으로 자극부위에 온도가 상승하는 결과를 얻었으며, 자기장 자극기 코일에서 발생하는 자체 발열량을 제거하기 위해 플라스틱 재질의 성형물로 신체와의 직접적인 접촉을 차단시켰으며 일정거리를 유지하여 실험하였다. 그 결과 비접촉을 통하여 순수하게 자기장의 펄스파형이 피부에 가까운 혈관을 자극하여 내부 전자기 에너지가 피부에 온도상승을 가져온 것으로 고찰된다.

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

• 음성과학
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• 제14권2호
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• pp.35-42
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• 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.