• 대한임상검사과학회지
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• 제45권2호
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• pp.77-85
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• 2013

Intraoperative Neurophysiological Monitoring (INM) is very useful in monitoring the motorsensory pathway and vascular circulation system during intraspinal, or intracranial neurosurgery. Brainstem Auditory Evoked Potentials (BAEPs) are for detecting the problems along the auditory pathways including, the eighth cranial nerve and brainstem. Motor Evoked Potentials (MEPs) is a useful adjunct to conventional monitoring of Somato-sensory Evoked Potentials (SEPs) during surgery. Visual Evoked Potentials (VEPs) has been regarded as having limited significance for the preservation of visual function during neurosurgical procedures. In this paper, we propose that the most appropriate averaging of the number of inspections in the inspection of each used in the operative field, is good and efficient, functionally.

• 대한의용생체공학회:의공학회지
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• 제18권4호
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• pp.421-428
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• 1997

초전도양자간섭소자(SQUID)를 이용한 자장센서는 현재 개발된 자장센서중에서 감도가 가장 우수한 소자로서 인체의 두뇌에서 발생하는 매우 미약한 자장에 측정이 가능하다. 뇌자도측정은 현재 많이 사용되고 있는 전기적인 측정(뇌파, 뇌유발전위) 에 비해 공간분해능이 우수하고, fMRI나 PET에 비해서는 시간분해능이 우수하므로 뇌기능연구에 유용하게 사용될 수 있다. 본 연구에서는 뇌자도 측정을 위하여 4-채널 SQUID시스템을 개발하였다. 개발된 시스템의 주요 특징은 새로운 방식의 SQUID센서를 채택함으로서 간단한 회로로써 SQUID구동이 가능하도록 하였으며, 검출코일의 신뢰성을 향상시키기 위하여 집적화된 평면형 코일을 사용하였다. 외부 환경잡음을 소거하기 위하여 자기차폐실을 설치하였고, 개발된 SQUID 시스템을 이용하여 뇌의 청각령으로부터 발생하는 자기신호를 측정하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권10호
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• pp.606-610
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• 2003

Noise subtraction using reference channel data has been used to improve signal-to-noise ratio in magnetoencephalography. In this paper, an adaptive noise subtraction model is proposed and parameters for the model are optimized. A criterion to determine an optimal update period for the filter coefficients is proposed based on the ratio of peak amplitude of evoked field (N100m) divided by the output standard deviation. Experiments are carried out using a 40 channel MEG system. From the experiments, the proposed noise subtraction method shows superior performances over existing non-adaptive methods. Two-dimensional topographic map is shown for a diagnosis with a cubic spline interpolation.

• 대한청각학회지
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• 제24권2호
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• pp.71-78
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• 2020

Background and Objectives: Currently limited information is available on speech stimuli processing at the subcortical level in the recipients of cochlear implant (CI). Speech processing in the brainstem level is measured using speech-auditory brainstem response (S-ABR). The purpose of the present study was to measure the S-ABR components in the sound-field presentation in CI recipients, and compare with normal hearing (NH) children. Subjects and Methods: In this descriptive-analytical study, participants were divided in two groups: patients with CIs; and NH group. The CI group consisted of 20 prelingual hearing impairment children (mean age=8.90±0.79 years), with ipsilateral CIs (right side). The control group consisted of 20 healthy NH children, with comparable age and sex distribution. The S-ABR was evoked by the 40-ms synthesized /da/ syllable stimulus that was indicated in the sound-field presentation. Results: Sound-field S-ABR measured in the CI recipients indicated statistically significant delayed latencies, than in the NH group. In addition, these results demonstrated that the frequency following response peak amplitude was significantly higher in CI recipients, than in the NH counterparts (p<0.05). Finally, the neural phase locking were significantly lower in CI recipients (p<0.05). Conclusions: The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech process in CI recipients.

• Journal of Audiology & Otology
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• 제24권2호
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• pp.71-78
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• 2020

Background and Objectives: Currently limited information is available on speech stimuli processing at the subcortical level in the recipients of cochlear implant (CI). Speech processing in the brainstem level is measured using speech-auditory brainstem response (S-ABR). The purpose of the present study was to measure the S-ABR components in the sound-field presentation in CI recipients, and compare with normal hearing (NH) children. Subjects and Methods: In this descriptive-analytical study, participants were divided in two groups: patients with CIs; and NH group. The CI group consisted of 20 prelingual hearing impairment children (mean age=8.90±0.79 years), with ipsilateral CIs (right side). The control group consisted of 20 healthy NH children, with comparable age and sex distribution. The S-ABR was evoked by the 40-ms synthesized /da/ syllable stimulus that was indicated in the sound-field presentation. Results: Sound-field S-ABR measured in the CI recipients indicated statistically significant delayed latencies, than in the NH group. In addition, these results demonstrated that the frequency following response peak amplitude was significantly higher in CI recipients, than in the NH counterparts (p<0.05). Finally, the neural phase locking were significantly lower in CI recipients (p<0.05). Conclusions: The findings of sound-field S-ABR demonstrated that CI recipients have neural encoding deficits in temporal and spectral domains at the brainstem level; therefore, the sound-field S-ABR can be considered an efficient clinical procedure to assess the speech process in CI recipients.

• 한국임상수의학회지
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• 제25권6호
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• pp.506-509
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• 2008

A 2-month-old, intact female white Bull Terrier presented because of suspected deafness. The coat color was predominantly white and the iris color, of both eyes, was brown. The dog did not respond to the owner's voice when the sound stimuli were presented outside of the visual field; however, the dog responded to visual gestures. The other physical, neurological, otoscopic, radiographic, and blood examinations were unremarkable. To assess the apparent deafness, brainstem auditory evoked responses (BAER) were recorded and analyzed in the dog with suspected deafness as well as a normal littermate. The response in the normal littermate consisted of a series of five wave peaks (I-V) with decreased amplitude and prolonged latency as the stimulus intensity decreased. The BAER from the dog suspected of deafness appeared as a flat line and did not reveal identifiable peaks that corresponded to those found in the normal littermate. Thus, congenital, sensorineural and bilateral deafness was confirmed by the BAER.

• Progress in Superconductivity
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• 제4권1호
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• pp.19-26
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• 2002

We have earlier developed a 40-channel SQUID system. An important figure of merit of a MEG system is the localization error, within which the underlying current source can be localized. With this system, we investigated the localization error in terms of the standard deviation of the coordinates of the ECDs and the systematic error due to inadequate modeling. To do this, we made localization of single current dipoles from tangential components of auditory evoked fields. Equivalent current dipoles (ECD) at N1m peak were estimated based on a locally fitted spherical conductor model. In addition, we made skull phantom and simulation measurements to investigate the contribution of various errors to the localization error. It was found that the background noise was the main source of the errors that could explain the observed standard deviation. Further, the amount of systematic error, when modeling the head with a spherical conductor, was much less than the standard deviation due to the background noise. We also demonstrated the performance of the system by measuring the evoked fields to grammatical violation in sentence comprehension.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2002년도 High Temperature Superconductivity Vol.XII
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• pp.10-10
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• 2002

• Progress in Superconductivity
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• 제4권2호
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• pp.114-120
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• 2003

We employed a method eliminating a temporally partial principal component (PC) of multichannel-recorded neuromagnetic fields for excluding spatially correlated noises from event-evoked signals. The noises in magnetoencephalography (MEG) are considered to be mainly spontaneous neuromagnetic fields which are spatially correlated. In conventional MEG experiments, the amplitude of the spontaneous neuromagnetic field is much lager than that of the evoked signal and the synchronized characteristics of the correlated rhythmic noise makes it possible for us to extract the correlation noises from the evoked signal by means of the general PC analysis. However, the whole-time PC of the fields still contains a little projection component of the evoked signal and the elimination of the PC results in the distortion of the evoked signal. Especially, the distortion will not be negligible when the amplitude of the evoked signal is relatively large or when the evoked signals have a spatially-asymmetrical distribution which does not cancel out the corresponding elements of the covariance matrix. In the period of prestimulus, there are only the spontaneous fields and we can find the pure noise PC that is not including the evoked signal. Besides that, we propose a method, called the extended temporal decorrelation method (ETDM), to suppress the distortion of the noise PC from remanent evoked signal components. In this study, we applied the Partial Principal component elimination method (PPCE) and ETDM to simulated signals and the auditory evoked signals that had been obtained with our homemade 37-channel magnetometer-based SQUID system. We demonstrate here that PPCE and ETDM reduce the number of epochs required in averaging to about half of that required in conventional averaging.

• 전자공학회논문지
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• 제51권10호
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• pp.213-220
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• 2014

시공간 분해능이 우수하고 비침습적으로 대뇌 신경활동의 측정이 가능한 뇌자도는 뇌기능 연구 및 뇌질환 진단에 유용한 진단용 의료기기이다. 순수 국내기술로 개발한 한국형 뇌자도 시스템을 임상시설(병원)에 설치하고 뇌질환 환자를 대상으로 유발자계를 측정, 분석하여 한국형 뇌자도 시스템의 임상 응용 가능성을 검토하였다. 1) 반측성 안면 경련 환자를 대상으로 소리자극에 대한 청각유발자계를 측정, 분석하여 안면신경과 청신경의 상호작용 여부 및 이명과의 연관성 검토, 2)뇌종양 환자의 정중신경 자극에 대한 체성감각 유발자계를 측정하여 뇌전증 유무에 따른 연관성 검토. 뇌자도 데이터의 분석 결과로부터 한국형 뇌자도 시스템이 뇌기능 연구 및 뇌질환 진단에 유용한 시공간적인 분석 정보를 제공할 수 있음을 시사하고 있다.