• 대한의용생체공학회:의공학회지
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• 제30권4호
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• pp.341-346
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• 2009

Cutaneous electrogastrography is the measurement of electrical activity of the stomach on the abdominal surface. The validity of cutaneous electrogastrography is dependent upon the quality of the recording technique. The locations of electrodes are an important issue. We examined the influences of the inter-electrode distance of bipolar leads on electrogastrography measurements. The sensitivity distributions of EGG leads were calculated based on a 2D body fat model and evaluated according to the region of interest sensitivity ratio (ROISR). We simulated the ROISR of the inter-electrode distance in relation to various body fat thicknesses. The distance between the electrodes was proportional to the distance between the ROI and the surface of the abdomen. The results imply that inter-electrode distance can be applied in electrogastrography according to human body fat thickness.

• Annals of Clinical Neurophysiology
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• 제12권1호
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• pp.11-15
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• 2010

Background: In belly-tendon (bipolar) montage, reference (R2) electrode placed on muscle's tendon has traditionally been considered to be electrically inactive. However, recent studies have revealed that R2 electrode is not simply referential, but actively contributes to compound muscle action potential (CMAP) waveform morphology. These findings suggest that CMAP onset latency and amplitude may also be influenced by the position of R2 electrode. This study was performed in order to evaluate the effect of R2 electrode position on CMAP onset latency and amplitude. Methods: We performed motor nerve conduction studies of median, ulnar, tibial and peroneal nerves on bilateral limbs of 20 normal subjects. We used traditional bipolar and monopolar montage and compared their CMAP onset latencies and amplitudes. In bipolar montage, recording (R1) electrode was placed on mid-belly of muscle with R2 electrode on the tendon of the muscle. In monopolar montage, R1 electrode was placed on the same site of bipolar montage, while R2 electrode was placed on the contralateral limb. Results: The mean CMAP onset latencies of median and peroneal nerves in bipolar montage were significantly different (p<0.05) with those in monopolar montage. And those of ulnar and tibial nerves were not significantly different (p>0.05). The mean CMAP amplitudes of all the tested nerves except ulnar nerve were significantly different (p<0.05). Conclusions: This study shows that change in R2 electrode position can affect the CMAP onset latency and amplitude, and these differences seem to be related to the generation of far field potential by CMAP.

• 대한전자공학회논문지
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• 제24권4호
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• pp.618-624
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• 1987

This paper describes the design and fabrication of a signal processing integrated circuit required for the recording and playback of VTR audio signal. The integrated circuit was designed using 8\ulcorner design rule and its chip size is 2.5x2.5mm\ulcorner It was fabricated using SST bipolar standard process technology. The measurement analysis of the fabricated circuit proves the satisfactory DC characteristics and its proper audio signal processing funcstion.

• 수면정신생리
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• 제8권1호
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• pp.67-71
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• 2001

Independent Component Analysis (ICA) is a blind source separation method using unsupervised learning and mutual information theory created in the late eighties and developed in the nineties. It has already succeeded in separating eye movement artifacts from human scalp EEG recording. Several characteristic sleep waves such as sleep spindle, K-complex, and positive occipital sharp transient of sleep (POSTS) can be recorded during sleep EEG recording. They are used as stage determining factors of sleep staging and might be reflections of unknown neural sources during sleep. We applied the ICA method to sleep EEG for sleep waves separation. Eighteen channel scalp longitudinal bipolar montage was used for the EEG recording. With the sampling rate of 256Hz, digital EEG data were converted into 18 by n matrix which was used as a original data matrix X. Independent source matrix U (18 by n) was obtained by independent component analysis method ($U=W{\timex}X$, where W is an 18 by 18 matrix obtained by ICA procedures). ICA was applied to the original EEG containing sleep spindle, K-complex, and POSTS. Among the 18 independent components, those containing characteristic shape of sleep waves could be identified. Each independent component was reconstructed into original montage by the product of inverse matrix of W (inv(W)) and U. The reconstructed EEG might be a separation of sleep waves without other components of original EEG matrix X. This result (might) demonstrates that characteristic sleep waves may be separated from original EEG of unknown mixed neural origins by the Independent Component Analysis (ICA) method.

• Journal of KIEE
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• 제11권1호
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• pp.32-40
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• 2001

This paper presents the detailed statistics on radiation field signatures associated with multiple-intracloud lightning discharges. A transient signal recording system was used to measure the electric and magnetic fields produced by lightning flashes. The measurements were made in th summers of 1995 through 1999, and the location of the observation station was in Inchon on the coast of the Yellow Sea in Korea(37$^{\circ}$25'N, 126$^{\circ}$ 39'E). Most of lightning flashes typically contains between two and five strokes. The individual intracloud stork radiation fields were the bipolar pulse. On the average, the ratio of the peak of the second stroke to the first stroke peak was 75.1$\pm$40.1% for the negative, and a fraction of the subsequent stroke peaks were higher than the first stroke peak. The greater the number of the subsequent stroke order, less time separations between strokes were produced. The mean of the depth of the dip was 81.2$\pm$27.9% for the positive polarity and 75.9$\pm$24.4% for the negative. The depth of the dip increased for the positive bipolar pulses and decreased for the negative as the number of the stroke order increased.

• 대한후두음성언어의학회지
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• 제14권2호
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• pp.83-87
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• 2003

Background and Objectives : Sphincteric function of the larynx, essential to lower airway protection, is most efficiently achieved through strong reflex adduction by both vocal cords. We hypothesize that central facilitation is an essential component of a bilateral adductor reflex and that its disturbance could result in weakened sphincteric closure. Materials and Method : Seven adult 20kg dogs underwent evoked response laryngeal electromyoraphy under 0.5 to 1.0 MAC isoflurane anesthesia. The internal branch of superior laryngeal nerve was stimulated through bipolar platinum-iridium electrodes and recording electrodes were positioned in the ipsilateral and contralateral thyroaryteonoid muscles. Results : Consistent threshold responses were obtained ipsilaterally under all anesthetic levels. However, contralateral reflex responses disappeared as anesthetic levels approached 1.0 MAC. Additionally, at 0.5 MAC, late responses (R2) were detected in one animal. Conclusion : Alteration of central facilitation by deepening anesthesia abolishes the crossed adductor reflex, predisposing to a weakened glottic closure response. Precise understanding of this effect may improve the prevention of aspiration in patients emerging from prolonged sedation or under heavy psychotropic control.

• 조명전기설비학회논문지
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• 제19권6호
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• pp.59-66
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• 2005

본 논문은 운방전에 의해서 방사된 전자계 펄스의 특징과 통계에 관한 것으로 LabVIEW 기반의 시변성 자계측정시스템을 구성하였다. 이 자계측정시스템의 주파수대역은 $300[Hz}{\sim}1[MHz]$이고, 응답감도는 2.78[mV/nT]이며, 검출된 자계 파형의 기록에는 수직해상도와 최대기록시간이 각각 12비트와 100[ms]인 데이터취득시스템이 적용하였다. 운방전에 의해서 발생한 전자계 펄스는 파두부분에 하나 또는 둘 이상의 빠른 펄스가 중첩된 양방성 파형으로 나타났다. 운방전의 평균지속시간은 약 $1.05{\pm}0.32[ms]$이었으며, 평균 8개의 양방성 펄스가 발생하였다.

• 대한임상검사과학회지
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• 제53권4호
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• pp.296-308
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• 2021

뇌파검사는 뇌전증을 가장 정확하고 빠르게 진단한다. 또한 뇌의 기능과 발작을 장소의 구애를 받지 않으면서 실시간으로 평가할 수 있는 중요한 검사이다. 뇌전증 분야에서는 뇌파검사지식과 임상경험이 많은 임상병리사가 PA를 하는 것이 적합하다. 전극 부착 방법은 국제 표준 10-20법을 기반으로 한다. 뇌파 판독은 주로 LB몽타주로 판독한다. 하지만 한 가지 몽타주만 이용하여 판독하는 것은 오류를 범할 수 있기 때문에, 상황에 맞게 2개 이상의 몽타주를 병용해서 판독한다. 뇌파에서 전위는 등고선의 형태로 보인다. 뇌파 진단에서 가장 중요한 원리는 과잉 판독이 아닌 과소 판독이다. 뇌파를 반복해서 기록할수록 더욱 민감하게 판독할 수 있다. 좋은 뇌파 판독을 위해서는 양질의 좋은 뇌파가 기록되어야 한다. 그러기 위해선 신경과 의사와 뇌파 기사의 관계가 매우 중요하다. 앞으로는 많은 판독 경험과 임상적 실무지식을 갖춘 임상병리사의 활동영역이 좀 더 확대되길 기대한다.

• Journal of Korean Neurosurgical Society
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• 제64권2호
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• pp.282-288
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• 2021

Objective : Electrooculography (EOG) records eyeball movements as changes in the potential difference between the negatively charged retina and the positively charged cornea. We aimed to investigate whether reliable EOG waveforms can be evoked by electrical stimulation of the oculomotor and abducens nerves during skull base surgery. Methods : We retrospectively reviewed the records of 18 patients who had undergone a skull base tumor surgery using EOG (11 craniotomies and seven endonasal endoscopic surgeries). Stimulation was performed at 5 Hz with a stimulus duration of 200 μs and an intensity of 0.1-5 mA using a concentric bipolar probe. Recording electrodes were placed on the upper (active) and lower (reference) eyelids, and on the outer corners of both eyes; the active electrode was placed on the contralateral side. Results : Reproducibly triggered EOG waveforms were observed in all cases. Electrical stimulation of cranial nerves (CNs) III and VI elicited positive waveforms and negative waveforms, respectively, in the horizontal recording. The median latencies were 3.1 and 0.5 ms for craniotomies and endonasal endoscopic surgeries, respectively (p=0.007). Additionally, the median amplitudes were 33.7 and 46.4 μV for craniotomies and endonasal endoscopic surgeries, respectively (p=0.40). Conclusion : This study showed reliably triggered EOG waveforms with stimulation of CNs III and VI during skull base surgery. The latency was different according to the point of stimulation and thus predictable. As EOG is noninvasive and relatively easy to perform, it can be used to identify the ocular motor nerves during surgeries as an alternative of electromyography.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권6호
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• pp.262-268
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• 2005

In this work, to obtain the detailed information about lightning electromagnetic field waveforms, the LabVIEW based-measurement system of time-changing magnetic fields was designed and constructed. The frequency bandwidth of the magnetic field measuring system ranges from 300 [Hz] to 1 [MHz], and the response sensitivity is 2.78 [mV/nT]. Data acquisition system with the resolution of 12 bits and memory capacity of 32 [Mbyte] was triggered by the magnetic field to be measured. The properties and parameters of the magnetic fields produced by cloud discharges were statistically investigated. The magnetic field waveforms radiated from cloud lighting discharges tend to be bipolar, with two or more narrow and several pulses superimposed on the initial front part. The recording length of the magnetic field measurement system is about 10 [ms]. The mean duration of cloud discharges is 1.3 [ms], and the number of outburst pulses for the period is 8 in average. The front times of the magnetic fields are 6.15 [$\mu$s] in average. The the zero-to-zero crossing times that is the initial half-cycle duration is widely dispersed and the mean value is 9.61 [$\mu$s], and the mean value of percentage depth of dip to opposite polarity is 41.1 [$\%$].