• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.335-338
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• 1993

텅스텐으로 만들어진 field emitter와 탄소로 만들어진 field emitter에서 생기는 step이나 spike 형태의 잡음에 대하여 비교 연구하였다. 그리고 dispenser 형태의 field emiter와 array 형태의 field emitter와 같은 새로운 형태의 field emitter를 설명하였다.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.199-207
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• 2003

The present study examined that in vivo/vitro test is investigated in normotensive sham-operated rats(NSR) and aldosterone-analogue deoxycorticosterone acetate (DOCA)-salt hypertensive rats(ADHR) and that the antiliypertensive effect was induced by silver spike point(SSP) electrical stimulation at meridian points(CV-3, -4, Ki-12, SP-6, LR-3, BL-25, -28, -32, -52), specifically, such as aldosterone in 24 hour urine analysis from normal volunteer. The heart weight, the tickness of vascular wall, collagen fiber and the systolic blood pressure were significantly increased in ADHR than that in NSR. The required time of PSS-induced resting tone and the phosphorylation of stress-activated protein kinase/c-Jun N-terminal protein kinase(SAPK/JNK) were significantly increased in ADHR than that in NSR. However, the Kv currents were significantly decreased in ADHR than that in NSR. The current of 1 Hz continue type of SSP electrical stimulation significantly decreased in excretion of urine aldosterone from normal volunteer. These results suggest that the development of aldosterone analogue-induced hypertension is associated with changed heart weight, content of collagen fiber, tickness of vascular wall, blood pressure, resting tone, voltage-dependent K+ current(Kv) and phosphorylation of SAPK/JNK, which directly affects blood pressure. Therefore the hypertension is a risk factor on cerebrovascular disease. Moreover, These results suggest that the SSP electrical stimulation, especially current of 1 Hz continue type, significantly regulates excretion of urine aldosterone from volunteer.

• The Journal of Korean Physical Therapy
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• v.23 no.2
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• pp.53-59
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• 2011

Purpose: This study was designed to compare the effects of transcutaneous electrical nerve stimulation (TENS) and silver spike point (SSP) therapy on current perception threshold (CPT) and mechanical pain threshold (MPT). Methods: Forty-five healthy adult male and female subjects were studied. Fourteen of them were males and twenty-one were females. Subject were randomly assigned to receive; (1) TENS (80/120 Hz alternating frequency), (2) SSP (3 Hz), or (3) no treatment (control group). Electric stimulation was applied over LI4 and LI11 on acupuncture points of the left forearm for 30 minutes. CPT and MPT were recorded before and after electrical stimulation. The data were analyzed using linear mixed models, with group treated as a between subject factor and time a within-subject factor. Results: At 30 minutes after cessation of electrical stimulation the CPT of C fibers and A${\delta}$fibers was reduced in the TENS group that of C fibers was reduced in the SSP group (p<0.05). After cessation of electrical stimulation, the MPT of C fibers and A${\delta}$fibers increased in the TENS group, and that of A${\delta}$fibers increased in the SSP group (p<0.05). Conclusion: After TENS and SSP stimulation, MPT of C fibers and A${\delta}$fibers were selectively increased. In particular, the TENS group showed increases in both C and A${\delta}$fibers, while the SSP group showed increases only in A${\delta}$fibers.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.5
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• pp.555-563
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• 2017

Electrical stimulation through retinal prosthesis elicits both short and long-latency retinal ganglion cell (RGC) spikes. Because the short-latency RGC spike is usually obscured by electrical stimulus artifact, it is very important to isolate spike from stimulus artifact. Previously, we showed that topographic prominence (TP) discriminator based algorithm is valid and useful for artifact subtraction. In this study, we compared the performance of forward backward (FB) filter only vs. TP-adopted FB filter for artifact subtraction. From the extracted retinae of rd1 mice, we recorded RGC spikes with $8{\times}8$ multielectrode array (MEA). The recorded signals were classified into four groups by distances between the stimulation and recording electrodes on MEA (200-400, 400-600, 600-800, $800-1000{\mu}m$). Fifty cathodic phase-$1^{st}$ biphasic current pulses (duration $500{\mu}s$, intensity 5, 10, 20, 30, 40, 50, $60{\mu}A$) were applied at every 1 sec. We compared false positive error and false negative error in FB filter and TP-adopted FB filter. By implementing TP-adopted FB filter, short-latency spike can be detected better regarding sensitivity and specificity for detecting spikes regardless of the strength of stimulus and the distance between stimulus and recording electrodes.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.535-540
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• 1998

This paper discusses a triple stage current source GTO inverter system for high power motor drives. The energy rebound circuit of the triple stage inverter not only controls the spike voltage of the GTO inverter but also facilitates PWM control of the thyristor rectifier operated at unity fundamental input power factor. Based on Pspice simulation and experiments, the principles and PWM pulse pattern for removing specific lower harmonics in the inverter's output current are discussed in detail.

• Journal of Biomedical Engineering Research
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• v.38 no.6
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• pp.342-351
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• 2017

The neural decoding is a procedure that uses spike trains fired by neurons to estimate features of original stimulus. This is a fundamental step for understanding how neurons talk each other and, ultimately, how brains manage information. In this paper, the strategies of neural decoding are classified into three methodologies: rate decoding, temporal decoding, and population decoding, which are explained. Rate decoding is the firstly used and simplest decoding method in which the stimulus is reconstructed from the numbers of the spike at given time (e. g. spike rates). Since spike number is a discrete number, the spike rate itself is often not continuous and quantized, therefore if the stimulus is not static and simple, rate decoding may not provide good estimation for stimulus. Temporal decoding is the decoding method in which stimulus is reconstructed from the timing information when the spike fires. It can be useful even for rapidly changing stimulus, and our sensory system is believed to have temporal rather than rate decoding strategy. Since the use of large numbers of neurons is one of the operating principles of most nervous systems, population decoding has advantages such as reduction of uncertainty due to neuronal variability and the ability to represent a stimulus attributes simultaneously. Here, in this paper, three different decoding methods are introduced, how the information theory can be used in the neural decoding area is also given, and at the last machinelearning based algorithms for neural decoding are introduced.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.179-181
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• 2009

고압 방전 램프는 점등 후부터 정상상태에 이르기까지 방전관 내부의 온도 및 압력이 광범위하게 변화하는 복잡한 동작 특성으로 모델링이 어렵다. 이러한 특성은 램프를 구동하는 안정기의 설계에 어려움이 따른다. 램프의 구동에는 초기 점화 시 높은 점화용 전압 펄스를 필요로 한다. 점화 후에 정상상태에 다다르면 램프 전극의 소모를 줄이기 위해 교류로 구동되어야 한다. 하지만 램프를 교류로 구동하게 되면 음향 공진 현상이 발생할 수 있다. 음향 공진 현상은 램프 구동 전류의 맥동성분이 큰 경우에도 발생을 할 수 있으므로 구동 전류의 맥동 성분의 크기는 최소화 돼야 한다. 램프의 수명시간을 길게 하려면, 안정기는 램프를 정격전력으로 구동하여야 한다. 따라서 안정기에서는 정전력 제어가 필요하게 된다. 램프 전류의 극성이 변화할 때, 램프 전류는 spike전류와 중첩이 된다. 본 논문에서는 spike 전류를 저주파구형파 램프 전류의 포락범위 안에 유지하고, 고주파 스위칭시손실을 줄이기 위해 소프트 스위칭 기법을 이용한 회로 설계를 제안했다. 제안된 방법은 시뮬레이션 및 이론적 수식적 방법으로 검증 했다.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.6
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• pp.658-663
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• 2015

In the previous work, we have proposed an integrate-and-fire neuron circuit and synaptic device based on the floating body MOSFET [1-3]. Integrate-and-Fire(I&F) neuron circuit emulates the biological neuron characteristics such as integration, threshold triggering, output generation, refractory period using floating body MOSFET. The synaptic device has short-term and long-term memory in a single silicon device. In this paper, we connect the neuron circuit and the synaptic device using current mirror circuit for summation of post synaptic pulses. We emulate spike-timing-dependent-plasticity (STDP) characteristics of the synapse using feedback voltage without controller or clock. Using memory device in the logic circuit, we can emulate biological synapse and neuron with a small number of devices.

• Sleep Medicine and Psychophysiology
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• v.2 no.2
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• pp.133-137
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• 1995

The author reviews current knowledge about what REM sleep is and where and how it is generated. REM sleep is the state in which our most vivid dreams occur. REM sleep is identified by the simultaneous presence of a desynchronized cortical EEG, an absence of activity in the antigravity muscles(atonia), and periodic bursts of rapid eye movements. Another characteristic phenomena of REM sleep are the highly synchronized hippocampal EEG of theta frequency and the ponto-geniculo-occipital(PGO) spike. All these phenomena can be explained in terms of changes in neuronal activity. Transection studies have determined that the pons is sufficient for generating REM sleep. Lesion studies have identified a small region in the lateral pontine tegmentum corresponding to lateral portions of the nucleus reticularis pontis oralis(RPO) and the region immediately ventral to the locus coeruleus, which is required for REM sleep. Unit recording studies have found a population of cells within this region that is selectively active in REM sleep. Cholinergic neurons of the giant cell field of pontine tegmentum(ETG), which is 'REM a sleep-on cells', has shown to be critically involved in the generation of REM sleep. Noradrenergic neurons of the locus coeruleus and serotonergic neurons of the dorsal raphe, which are called 'REM sleep-off cells', appear to act in a reciprocal manner to the cholinergic neurons. It is proposed that the periodic cessations of discharge of 'REM sleep-off cells' during REM sleep might be significant for the prevention of the desensitization of receptors of these neurons.

• Animal cells and systems
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• v.13 no.4
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• pp.357-362
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• 2009

Hesperidin, the most abundant polyphenolic compound found in citrus fruits, has been known to possess neuroprotective, sedative, and anticonvulsive effects on the nervous system. In a recent electrophysiological study, it was reported that hesperidin induced biphasic change in population spike amplitude in hippocampal CA1 neurons in response to both single spike stimuli and theta-burst stimulation depending on its concentration. However, the precise mechanism by which hesperidin acts on neuronal functions has not been fully elucidated. Here, using whole-cell patch-clamp recording, we revealed that hesperidin did not affect excitatory synaptic activities such as basal synaptic transmission and theta-burst LTP. Moreover, in a current injection experiment, spike number, resting membrane potential and action potential threshold also remained unchanged. Taken together, these results indicate that the effects of hesperidin on the neuronal functions such as spiking activity might not be attributable to either modification of excitatory synaptic transmissions or changes in membrane excitability in hippocampal CA1 neuron.