• 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.

• 한국광학회지
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• 제3권4호
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• pp.266-272
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• 1992

화염내부의 온도분포를 측정하기 위하여 코헤런트 라만분광 기술을 연구하였다. 측정의 공간분해능을 높이기 위하여 상자형 위상정합 방법을 사용하여 CARS 신호를 측정하였다. 측정된 CARS신호를 이용하여 화염의 온도를 계산하는 프로그램을 연구하였다. 섭동이론을 이용하여 에너지 간격법칙으로 기술되는 질소 분자의 라만 Q-가지 분광선의 선폭확대 효과를 온도계산 프로그램에 삽입하였다. 에너지 간격법칙을 이용하여 계산된 화염내부의 온도 분포가 열전대로 측정된 오도와 계산에 의해 구해진 단열 화염 온도와 적절히 일치함을 확인하였다.

• ETRI Journal
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• 제45권4호
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• pp.581-593
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• 2023

This paper proposes four-ring slot resonator-based MIMO antennas of 75×150 mm² without and with CSRR structures in the sub-6-GHz range. These orthogonal-fed antennas have shown diverse characteristics with dual polarization. L-shaped parasitic structures have increased the isolation (i.e., >40 dB) in the single-element antenna over the band of 3.4 GHz-3.8 GHz. A set of three CSRR structures in the MIMO antenna reduced the coupling between antenna ports placed in an inline arrangement and enhanced the isolation from 12 dB to 20 dB and the diversity characteristics. The S-parameters of both MIMO antennas are measured and used to evaluate MIMO parameters like ECC, TARC, MEG, and channel capacity loss. The simulation results show the variations in the gain and directivity on exciting linear and dual polarizations. The diversity performance of the reported MIMO antennas is suitable for 5G applications.

• 한국조명전기설비학회지:조명전기설비
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• 제26권4호
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• pp.25-33
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• 2012

• 대한동의생리학회:학술대회논문집
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• 대한동의생리학회 2005년도 정기총회 및 동계학술대회
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• pp.24-24
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• 2005

• 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.

• 대한물리의학회지
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• 제8권1호
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• pp.127-135
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• 2013

PURPOSE: This study examined the effects of exercise of diverse intensities on the recovery of articular cartilage in osteoarthritic rats. METHODS: Over a period of four weeks, the authors applied treadmill exercise programs of diverse intensities to Sprague-Dawley rats, to which intra-articular injection of monosodium iodoacetate(MIA, 3mg/$50{\mu}l$, diluted in saline) was applied to the right knee joint to induce osteoarthritis. The four-week exercise program was not carried out with the control group(CG, n=10). Exercise programs of applicable intensities were applied to the low-intensity exercise group(LEG, n=10), moderate-intensity exercise group(MEG, n=10), and high-intensity exercise group(HEG, n=10) over the four weeks. Observations were made of morphological changes in the rats' articular cartilage, using hematoxylin and eosin stains. RESULTS: there were significant differences(p<.05) in the comparison of articular damage scores between the four groups involved. Articular cartilage damage scores were found to be significantly lower in the LEG, MEG, and HEG than in the CG, indicating that exercise helped with the recovery of cartilage. Of these latter three groups, the MEG showed the highest level of recovery, while the HEG showed the lowest. CONCLUSION: These study results suggest that exercise is effective in treating OA. They also indicate that in prescribing exercise to treat osteoarthritic patients, exercise of moderate intensity is most suitable to patients' physical conditions, rather than low or high intensity, maximizes, and so should be used to maximize the effects of therapy.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.159-165
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• 2003

뇌자도 측정을 위해 고감도 superconducting quantum interference device (SQUID) 자력계 및 37채널 뇌자도 측정장치를 제작하고 동작특성을 조사하였다. 자속-전압 변환계수 및 변조전압 진폭이 큰 double relaxation oscillation SQUID (DROS)를 사용함으로서 구동회로를 간단히 하였고 안정한 SQUID 동작을 실현할 수 있었다. DROS 자력계를 설계 및 제작한 결과 자력계의 평균 백색잡음은 약 3 fT/√Hz으로서 우수한 자장감도를 가짐을 확인하였다 머리의 평균곡률을 기반으로 37개의 자력계를 반구형으로 배치시켰으며, 외부잡음을 줄이기 위해 신호채널 외에 11개의 기준채널을 설치하여 소프트웨어 방법으로 합성미분계 및 적응필터링을 형성할 수 있도록 하였다 저잡음 듀아를 제작하여 동작특성을 측정한 결과 듀아 열자기 잡음이 자력계 잡음에 비해 무시할 수 있는 수준이었으며, 듀아의 용량은 30 L, 액체헬륨 증발율은 4 L/d이다. 제작된 시스템을 이용하여 청각유발 신호를 측정하고, 디지털 신호처리 및 전류원 국지화 프로그램을 구성하여 전류원의 위치를 추정함으로서 개발된 시스템을 뇌자도 측정에 활용하였다.

• Journal of Korean Neurosurgical Society
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• 제47권1호
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• pp.17-25
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• 2010

Objective: The focus of this study is brain plasticity associated with semantic aspects of language function in patients with medial temporal lobe epilepsy (mTLE) Methods: Using longitudinal functional magnetic resonance imaging (fMRI), patterns of brain activation were observed in twelve left and seven right unilateral mTLE patients during a word-generation task relative to a pseudo-word reading task before and after anterior temporal section surgery. Results: No differences were observed in precentral activations in patients relative to normal controls (n = 12), and surgery did not alter the phonological-associated activations. The two mTLE patient groups showed left inferior prefrontal activations associated with semantic processing (word-generation>pseudo-word reading), as did control subjects. The amount of semantic-associated activation in the left inferior prefrontal region was negatively correlated with epilepsy duration in both patient groups. Following temporal resection, semantic-specific activations in inferior prefrontal region became more bilateral in left mTLE patients, but more left-lateralized in right mTLE patients. The longer the duration of epilepsy in the patients, the larger the increase in the left inferior prefrontal semantic-associated activation after surgery in both patient groups. Semantic activation of the intact hippocampus, which had been negatively correlated with seizure frequency, normalized after the epileptic side was removed. Conclusion: These results indicate alternation of semantic language network related to recruitment of left inferior prefrontal cortex and functional recovery of the hippocampus contralateral to the epileptogenic side, suggesting an intra- and inter-hemispheric reorganization following surgery.

• 대한물리의학회지
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• 제9권2호
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• pp.193-200
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• 2014

PURPOSE: This study examined the effects of treadmill exercise of diverse intensities on the expression of IL-$1{\beta}$ (interleukine-$1{\beta}$) in the spinal cord in osteoarthritis rats. METHODS: The authors applied treadmill exercise of diverse intensity for 4 weeks to Sprague-Dawley rats to which intra-articular injection of monosodium iodoacetate(MIA, $3mg/50{\mu}l$, diluted in saline) was applied in the right knee joint to induce osteoarthritis. The four-week exercise was not applied to the control group(CG, n=15), while exercise of applicable intensity was applied to the low-intensity exercise group(LEG, n=15), moderate-intensity exercise group (MEG, n=15), and high-intensity exercise group(HEG, n=15) for four weeks. Observations were made of expression of IL-$1{\beta}$ in the spinal cord in osteoarthritis rats using western blot analysis. RESULTS: There were significant differences(p<.05) in the comparison of expression of IL-$1{\beta}$ in the spinal cord between the four groups involved. And the LEG and MEG had reduced expression of IL-$1{\beta}$ significantly than the CG(p<.05); in particular, the MEG showed the lowest expression. On the other hand, the HEG had more elevated expression of IL-$1{\beta}$ significantly than the CG(p<.05). CONCLUSION: As a result, factors that induce neuropathic pain such as IL-$1{\beta}$ are reduced; thus, the recovery of damaged neurons is improved and neuropathic pain is reduced. Further, when prescribing exercise to treat osteoarthritis patients, exercise of moderate intensity suitable for patients' physical conditions, rather than high intensity, maximizes the effects of this therapy.