• 대한물리치료과학회지
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• 제2권2호
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• pp.465-479
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• 1995

We randomly assigned 61 healthy subjects(male 14, female 47) to compare the experimental pain threshold and skin temperature between high mode TENS and burst mode TENS. In this study, 61 subjects were divided into three groups ; high mode TENS(n=20), burst mode TENS (n=20), and control group(n=21). Experimental pain thresholds and skin temperatures were measured before, immediately after cessation of stimulation, and at 30 minutes post stimulation. Stimulation was applied to the dorsal surface of the forearm(L14, LI10). Pain thresholds were measured by chronaxie meter. Skin temperature were measured by electrical digital thermometer. The results are as follows ; 1. There were no statistical difference in the pain threshold and skin temperature at before TENS stimulation among the three groups(p>0.05). 2. The pain threshold and skin temperature in burst mode TENS group was significantly higher and longer effect than that in high mode TENS group and control group(p<0.01). 3. The pain threshold in burst mode TENS group decreased to prestimulation levels by 30 minutes poststimulation. 4. The skin temperature in burst mode TENS group decreased to prestimulation levels by 20 minutes poststimulation. 5. The skin temperature was significantly difference among three group at immediately after, and at 30 minutes poststimulation and the skin temperature in burst mode TENS group was significantely higher than that in two groups(p<0.001). 6. The increasing rate of pain threshold in high mode TENS group after immediately cassation of stimulation was 24.3%(p<0.001). 7. The increasing rate of pain threshold in burst mode TENS group after immediately cessation of stimulation was 93.5% (p<0.001).

• 대한한방소아과학회지
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• 제14권2호
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• pp.1-32
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• 2000

It has long been known that SOAT is effective for sudden palpitation occurring unexpectedly in Oriental Medicine. However, effect of SOAT on the isolated heart has not been studied yet. The purpose of this study is to investigate the effect of SOAT on hemodynamics and ECG of isolated rat hearts induced by electrical stimulation using Langendorff perfusion apparatus for nonworking heart. SOAT extract was manufactured by water-alcohol precipitated method. Sprague-Dawley rats weighting $120{\sim}150g$ were used for the experiments, Subject animals were divided into four groups, which are consisted of 1) control(Group orally administered by normal saline 1ml for 14days), 2) sample A(Group orally administered by SOAT extract 1ml for 14days), 3) sample C(Group injected by SOAT extract 0.5ml after stimulation, 4) sample C(Group injected by SOAT extract 1ml after stimulation. To evluate the effects of SOAT on hemodynamics and ECG of isolated rat heart induced by stimulation, heart rate, left ventricular pressure, systolic power, diastolic power, coronary artery perfusion volume and ECG were measured using Langendorff apparatus in both stimulation mode(5 volts, 450 beats/min) and arrythmic mode(5 volts, 420 beats/min including 60 beats/min) The results obtained are as follows : 1. After receiving stressful electrical stimuli, isolated heart showed the heart rate, left ventricular pressure, systolic power, diastolic power, coronary artery perfusion volume were all decreased temporarily, but perfusion continued longer recovery to the control state appeared. However, the coronary artery perfusion volume diminished continuously. 2. The heart rates did not change significantly with both stimulation mode and arrhythmic mode, among experimental groups. 3. The left ventricular pressure showed with both stimulation mode and arrhythmic mode, the significant changes(p<0.05) especially in the injection sample group. In case of stimulation mode, low concentration injection group(0.5ml) was more significantly increased rather than high concentration group(1ml) and in case of arrhythmic mode, high density group(1ml) was so increased than the other(0.5ml). 4. For the systolic power and diastolic power, no significant changes were noticed in the stimulation mode, but in the arrhythmic mode of injection sample groups, significant change(p<0.05) was noticed in both systolic power and diastolic power. Specially the high concentration group(1ml) showed more significant increase than the low concentration group. 5. For the coronary artery perfusion volume, no significant change difference among sample groups was observed in both the stimulation mode and the arrhythmic mode. 6. For the ECG recordings, arrhythmia was induced by electrical stimulus of arrythmia mode and after the stimulus was removed, irregular wave appeared temporarily, but as perpusion continued, recovery to the control state was abtained like the stimulation mode. According to the above results, SOAT significantly changed the hemodynamic data from the electrically stressed, isolated hearts of connected Langendorff perfusion apparatus and we propose SOAT has the direct effects on the muscular function of heart.

• Journal of Magnetics
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• 제16권3호
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• pp.246-252
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• 2011

A high-voltage power supply has been built for activation of the brain via stimulation using a Full Wave Cockroft-Walton Circuit (FWCW). A resonant half-bridge inverter was applied (with half plus/half minus DC voltage) through a bidirectional power transistor to a magnetic stimulation device with the capability of producing a variety of pulse forms. The energy obtained from the previous stage runs the transformer and FW-CW, and the current pulse coming from the pulse-forming circuit is transmitted to a stimulation coil device. In addition, the residual energy in each circuit will again generate stimulation pulses through the transformer. In particular, the bidirectional device modifies the control mode of the stimulation coil to which the current that exceeds the rated current is applied, consequently controlling the output voltage as a constant current mode. Since a serial resonant half-bridge has less switching loss and is able to reduce parasitic capacitance, a device, which can simultaneously change the charging voltage of the energy-storage condenser and the pulse repetition rate, could be implemented. Image processing of the brain activity was implemented using a graphical user interface (GUI) through a data mining technique (data mining) after measuring the vital signs separated from the frequencies of EEG and ECG spectra obtained from the pulse stimulation using a 90S8535 chip (AMTEL Corporation).

• 대한의용생체공학회:의공학회지
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• 제11권1호
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• pp.1-4
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• 1990

Functional neuromuscular stimulation(FNS)를 사용하여 하반선마비사가 앉은 상태에서부터 일어나 균형을 유지할 수 있도록 하기 위하여 FNS의 자동제어 시스댐을 개발하였다. Output feedback gain matrix를 최적제어이론을 사용하여 계산하기 위하여 비선형 선체모델을 직립위치에 대하여 선형화하였다. 제어기는 측정된 output에 의하여 매순간 각 선체조인트에 필요한 torque할 계산 하며, 이 조인트 torque는 근육이 최소한의 에너지를 사용하게끔 각 단육에 배분된다. 컴퓨터 시뮬레이션결과, 이 제어 시스템을 사용하여 각 조인트가 약 45도 정도 구부버진 상태에서 부터 직립위치를 회복할 수 있으며 팔의 움직임으로 대표되는 외부로부터의 방해를 반았블 때에도 직립 위치를 자동적으로 유지할 수 있었다.

• 한국전문물리치료학회지
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• 제9권2호
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• pp.115-131
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• 2002

Functional electrical stimulation (FES) training of the knee extensors is a useful way to rehabilitate the ability to stand and walk. However, training using FES has not been able to solve the problem of fatigue; clinical application of FES quickly produces muscle fatigue, due to the continuous activation of the muscles of the lower extremity. Therefore, reduction of muscle fatigue is an important factor in increasing the effectiveness of FES training in paraplegia. Intermittent high frequency alternating stimulation is a method that combines the advantages of high frequency (leading to strong muscle contractions) and alternating stimulation (reducing muscle fatigue), thereby continuously strengthening muscles. It is not known whether low frequency simultaneous stimulation results in stronger muscle contraction than high frequency alternating stimulation. This study compared the effectiveness of high frequency alternating stimulation with low frequency synchronized stimulation. Muscle power using FES on the quadriceps of 20 normal subjects were compared. Intermittent high frequency alternating stimulation did not produce more powerful muscle contraction than intermittent low frequency synchronized stimulation, because the muscle characteristics differed individually. Significant individual variation according to muscle characteristics was founded when applying FES. Accordingly, when physical therapists use FES to treat patients, they must be aware of individual variation in muscle characteristics.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.205-211
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• 2010

In this study, a Magnetic stimulation Pulse Train control technique is introduced and applied to Flyback converter operating in discontinuous conduction mode. In contrast to the conventional pulse width modulation control scheme, the principal idea of a Magnetic stimulation Pulse Train is to achieve output voltage regulation using high and low power pulses. The proposed technique is applicable to any converter operating in discontinuous conduction. However, this work mainly focuses on Flyback topology. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.521-524
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• 2009

신경자극반응 측정 플랫폼을 구현하는데 있어서 손가락 움직임을 감지하는 것이 중요한 요소로 작용하고 있다. 이것은 손가락의 움직임에 따라 신경자극과 근육반응이 달라지기 때문이다. 즉, 손가락의 움직임을 감지해서 신경 자극 Actuator 및 근육 반응 감지를 위한 H/W 개발이 필요한 것이다. 또한 임베디드 기반으로 가기위한 저전력 CPU를 사용하였다. H/W 구성은 isolation power부분, 정전류조절, High impedance INA, 증폭기부분이 있으며 Micro-controller에서는 stimulus mode 및 Current 의 상태를 통제하고, AD converter를 통해 얻어진 Low Data를 처리 시스템을 구현한다.

• 한국정보통신학회논문지
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• 제14권6호
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• pp.1505-1510
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• 2010

본 논문은 근육의 기능을 조절하는 신경말단에 전기적인 자극을 가하여 신경의 반응 정도를 측정하는 플랫폼 구현에 관한 연구로써, 전기 자극에 대한 신경반응이 가해지는 전류량, 가해지는 전류지속시간, 전극위치에 따른 반응을 측정하였다. 신격자극의 전극 위치는 표면말달 운동신경이면 어느 신경이든지 가능하고, 신격자극 양식에는 단순연축자극(Single Twitch Stimulation), 사연속자극(Train-of-four, TOF), 두 집단 발사자극(Double Burst Stimulation, DBS)이 있다. 임베디드 시스템기반으로 가기위한 저전력 MCU를 선정하고, 기본적인 신경자극반응 측정 센서의 민감도를 알아보기 위해 센서 인터페이스를 구성하여 반응정도를 측정해야 한다. 그리고 측정된 Data의 정확도를 높이기 위해 고성능의 AD Convertor 선정하여 플랫폼을 구현하였다.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.166-170
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• 2009

NIRS (Near-infrared spectroscopy) is a relatively, new, non-invasive, and non-ionizing method of measuring hemodynamic responses in thick biological tissues such as the cerebral cortex. In this study, we measured the hemodynamic responses of the rat barrel cortex to whisker stimulation by using a frequency-domain NIRS system. We designed multiple optical probes comprising multi-mode optical fibers and manipulating arms, both of which can be easily applied to small animals. Various electrical stimulations were applied to rat whiskers at different voltage levels and stimulation frequencies. Our results show that the hemodynamic responses are highly dependent on the stimulation voltage level, and not so much on stimulation frequency. This paper suggests that NIRS technology is highly suitable for the study of small animal brains.

• 대한약리학회지
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• 제30권1호
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• pp.67-73
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• 1994

Na-Ca 교환은 calcium 이온을, 세포 내외의 Na 이온 농도차에 의해서 형성되는 원동력의 방향에 따라, 세포내로(역방향 Na-Ca 교환), 혹은 세포밖으로(정방향 Na-Ca 교환) 이동시킨다. 그러므로 Na-Ca 교환은 심근 수축 운동의 조절 기전의 하나로 받아 들여지고 있다. 그러나, 세포내의 Na 이온 농도는 항상 세포외의 농도보다 낮으므로, 역방향 Na-Ca 교환의 존재와 아울러 이의 심근 수축에 있어서의 역할 가능성에 대해 많은 연구자들이 회의를 가지고 있는 것이 사실이다. 그러므로 본 연구는 흰쥐의 좌심방을 이용하여, 역방향 Na-Ca 교환의 존재 여부와 그 역할의 존재 가능성을 추구하여 보고자 하였다. 흰쥐의 좌심방은 전기장 자극(0.5msec, supramaximal voltage)으로 수축을 유발하고, 자극 빈도를 안정시 4Hz에서 0.4, 1, 8Hz로 변동시킬때 그 수축 장력에서 특징적인 역 사다리 효과(negative staircase effect)가 나타내었으나, 이때 $^{45}Ca$ 섭취는 저빈도로 갈수록, 또한 고빈도로 갈수록 증가되는 이원적인 증가를 나타내었다 자극 빈도를 4Hz 에서 0.4Hz로 변동시에는 수축 장력이 특징적인 삼단계 변환, 즉 급격히 증가하는 첫단계에 이어 급격하게 감소하는 이단계와 안정되어지는 삼단계로 나타났다. $^{45}Ca$ 섭취도 장력 변동과 같은 양상으로 처음 30초 동안에 현저하게 증가한 후 감소되었다. Na-Ca 억제 약물인 benzamil은 $10^{-5}M$에서부터 $3{\times}10^{-4}M$까지 용량에 비례하여 특히 초기의 장력증가를 봉쇄하였다. Bay K-8644$(3{\times}10^{-5}M)$ 처치는 자극 빈도 감소에 따른 수축력 증가를 현저하게 항진시켰으며, benzamil처치는 이때에도 억압을 나타내었다. Verapamil $3{\times}10^{-5}M$ 전처치시에는 4Hz 자극시의 수축 운동은 완전히 소실시켰으나, 0.4 혹은 1 Hz로 바꿈에 따라 수축 운동이 재현되었다. 이때 $^{45}Ca$ 섭취는 verapamil을 전처치하지 않은 경우보다 현저하게 항진되었다. 이상의 결과로 보아, 흰쥐의 좌심방에서 자극 빈도 감소후에는, 먼저 역방향 Na-Ca 교환에 의해 calcium이온이 세포내로 유입되어 수축운동의 항진이 유발되고, 이어 Na-Ca 교환이 정방향으로 변환되어 calcium이온을 세포밖으로 유출시킴에 따라 수축 운동이 감소된다고 생각한다.