• 한국방사선학회논문지
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• 제13권7호
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• pp.961-968
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• 2019

본 연구는 CT를 이용한 뇌혈관 추출 검사에서 이중에너지 기법을 활용하여 각 에너지 준위별 뇌혈관 조영술의 유용성을 평가하였다. 방법은 CT 뇌혈관 조영술을 시행한 환자 15명의 DE 영상과 SE 영상을 대상으로 하였다. 영상의 분석은 MCA, 뇌실직 조직, Background에 ROI를 설정하여 평균값, 표준편차 및 SNR, CNR 값을 구하고, SE영상과 비슷하게 구현되는 에너지 영역을 알아보았다. Likert 5점 척도 육안평가를 병행한 결과 DE 40 keV와 SE 120 kVp에서 가장 선명한 MCA 영상을 확인 하였다(p>0.05). SE영상의 SNR 값은 DE영상의 40 keV에너지 준위값과 비슷하게 측정되었고, 40 keV와 50 keV의 저에너지 준위의 영상이 SNR이 높게 측정되어 고에너지 준위의 영상에 비해 대조도가 높아 뇌혈관질환을 유용하게 관찰할 수 있을 것으로 사료된다.

• Journal of Korean Neurosurgical Society
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• 제60권5호
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• pp.504-510
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• 2017

Objective : To investigate the morphological and hemodynamic parameters associated with middle cerebral artery (MCA) bifurcation aneurysm rupture. Methods : A retrospective study of 67 consecutive patients was carried out based on 3D digital subtraction angiography data. Morphological and hemodynamic parameters including aneurysm size parameters (dome width, height, and perpendicular height), longest dimension from the aneurysm neck to the dome tip, neck width, aneurysm area, aspect ratio, Longest dimension from the aneurysm neck to the dome tip (Dmax) to dome width, and height-width, Bottleneck factor, as well as wall shear stress (WSS), low WSS area (LSA), percentage of LSA (LSA%) and energy loss (EL) were estimated. Parameters between ruptured and un-ruptured groups were analyzed. Receiver operating characteristics were generated to check prediction performance of all significant variables. Results : Sixty-seven patients with MCA bifurcation aneurysm were included (31 unruptured, 36 ruptured). Dmax (p=0.008) was greater in ruptured group than that in un-ruptured group. D/W (p<0.001) and the percentage of the low WSS area ($0.09{\pm}0.13$ vs. $0.01{\pm}0.03$, p<0.001) were also greater in the ruptured group. Moreover, the EL in ruptured group was higher than that in unruptured group ($6.39{\pm}5.04$ vs. $1.53{\pm}0.86$, p<0.001). Multivariate regression analysis suggested D/W and EL were significant predictors of rupture of MCA bifurcation aneurysms. Correlation analyses revealed the D/W value was positively associated with the EL (R=0.442, p<0.01). Conclusion : D/W and EL might be the most two favorable factors to predict rupture risk of MCA bifurcation aneurysms.

• Smart Structures and Systems
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• 제8권1호
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• pp.107-117
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• 2011

Biological sensory systems continuously monitor and analyze changes in real-world environments that are relevant to an animal's specific behavioral needs and goals. Understanding the sensory mechanisms and information processing principles that biological systems utilize for efficient sensory data acquisition may provide useful guidance for the design of smart-sensing systems in engineering applications. Weakly electric fish, which use self-generated electrical energy to actively sense their environment, provide an excellent model system for studying biological principles of sensory data acquisition. The electrosensory system enables these fish to hunt and navigate at night without the use of visual cues. To achieve reliable, real-time task performance, the electrosensory system implements a number of smart sensing strategies, including efficient stimulus encoding, multi-scale virtual sensor arrays, task-dependent filtering and online subtraction of sensory expectation.

• 전자공학회논문지B
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• 제30B권2호
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• pp.51-58
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• 1993

This paper describes the development of a speaker-dependent isolated word recognizer as applied to voice dialing in a car noise environment. for this purpose, several methods to improve performance under such condition are evaluated using database collected in a small car moving at 100km/h The main features of the recognizer are as follow: The endpoint detection error can be reduced by using the magnitude of the signal which is inverse filtered by the AR model of the background noise, and it can be compensated by using variants of the DTW algorithm. To remove the noise, an autocorrelation subtraction method is used with the constraint that residual energy obtainable by linear predictive analysis should be positive. By using the noise rubust distance measure, distortion of the feature vector is minimized. The speech recognizer is implemented using the Motorola DSP56001(24-bit general purpose digital signal processor). The recognition database is composed of 50 Korean names spoken by 3 male speakers. The recognition error rate of the system is reduced to 4.3% using a single reference pattern for each word and 1.5% using 2 reference patterns for each word.

• 대한방사선기술학회지:방사선기술과학
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• 제8권2호
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• pp.77-81
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• 1985

In this experiments the operation of the Geiger-Mueller tube is investigated by measuring the relationship between the count rate and the applied voltages, The length and slope of the plateau are characteristic of the tube. In our experiments, the average plateau length of the tube is extend for about 100 [V] and the slope 0.017 [%/V]. For normal counting purposes the working voltage is usually selected at value about 50 volts larger than the threshold of the plateau. To investigate the absorption of beta particles by matter. We performed an absorption experiments by using the Al absorber and Sr-90 ($0.125{\mu}Ci$) beta source. The maximum range of the beta radiation can be determined by visual extrapolation of the curve after subtraction of the constant background-rate and the maximum beta energy 2.09 [MeV] can be calculated from the range using an experimental relation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.59-61
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• 2002

This research investigates electron beam to specification energy to Module that was generalized and schematized difference of curved line after existing V-I efficiency characteristic curve and irradiation. And will analyze cause of Si crystal Solar cell's efficiency addition and subtraction by 80keV electron beam investigation.

• 센서학회지
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• 제15권3호
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• pp.186-191
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• 2006

In general, Cerenkov light is produced by a charged particle that passes through a medium with a velocity greater than that of visible light. Although the wavelength of Cerenkov light is very broad, the peak is in the almost visible range from 400 to 480 nm. Therefore, it always causes a problem to detect a real light signal that is generated in the scintillator on the fiber-optic sensor tip for dose measurements of high-energy electron beam. The objectives of this study are to measure, characterize and remove Cerenkov light generated in a fiber-optic radiation sensor tip to detect a real light signal from the scintillator. In this study, the intensity of Cerenkov light is measured and characterized as a function of incident angle of electron beam from a LINAC, and as a function of the energy of electron beam. As a measuring device, a photodiode-amplifier system is used, and a subtraction method using a background optical fiber is investigated to remove Cerenkov light.

• 전기화학회지
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• 제2권2호
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• pp.93-97
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• 1999

유해성 유기물을 효과적으로 분해시키는데 이용되는 Ag(II)이온에 의한 전기화학적 매개산화 공정의 한계전류밀도를 예측하기 위하여 질산전해질의 농도, Ag(I) 이온의 농도 및 온도변화에 따른 Ag(I)/Ag(II) 이온쌍의 cyclic voltammogram을 백금전극에서 얻었으며, 피크전류로부터 Ag(I) 이온의 확산계수를 구하였다. Ag(I)/Ag(II) 이온쌍의 산화환원 반응은 물 분해 반응에 의해 크게 영향을 받았으며 백그라운드 보정을 통하여 정확한 피크전류를 측정할 수 있었다. Ag(I) 이온의 확산계수를 질산용액의 점도 및 온도의 함수로 나타냄으로써 전기화학적 매개산화공정의 한계전류밀도를 용이하게 예측할 수 있는 실험식을 제시하였다.

• Journal of Korean Neurosurgical Society
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• 제61권2호
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• pp.167-179
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• 2018

The prevalence of patients with adult spinal deformity (ASD) has been reported as high as 68%. ASD often leads to significant pain and disability. Recent emphasis has been placed on sagittal plane balance and restoring normal sagittal alignment with regards to the three dimensional deformity of ASD. Optimal sagittal alignment has been known to increase spinal biomechanical efficiency, reduce energy expenditure by maintaining a stable posture with improved load absorption, influence better bony union, and help to decelerate adjacent segment deterioration. Increasingly positive sagittal imbalance has been shown to correlate with poor functional outcome and poor self-image along with poor psychological function. Compensatory mechanisms attempt to maintain sagittal balance through pelvic rotation, alterations in lumbar lordosis as well as knee and ankle flexion at the cost of increased energy expenditure. Restoring normal spinopelvic alignment is paramount to the treatment of complex spinal deformity with sagittal imbalance. Posterior osteotomies including posterior column osteotomies, pedicle subtraction osteotomies, and posterior vertebral column resection, as well anterior column support are well known to improve sagittal alignment. Understanding of whole spinal alignment and dynamics of spinopelvic alignment is essential to restore sagittal balance while minimizing the risk of developing sagittal decompensation after surgical intervention.

• 유기물자원화
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• 제24권2호
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• pp.31-39
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• 2016

저수조는 유입/유출량의 시간적인 편차 때문에 필요하다. 저수조 용량 산정하기 위해서 공급(예, 강수) 누적 량과 요구(예, 관수) 누적 량의 차이를 사용한다. (-)와 (+)영역의 상관없이 누적 량 차의 절댓값 최대치가 되었을 때 용량의 산정이 이루어진다. 본 논문에서는, 온실 시설물의 강수와 관수를 이용하여 비선형적인 공급이나 요구량에서도 이를 적용하여 용량을 산정하였고, 비선형적인 변화가 커졌을 시에도 적용 할 수 있음을 증명하였다. 그리고 모니터링에 대한 시간 간격이 작아짐에 따라서, 저수조 용량이 증가되며, 강수량의 경우에는 약 10일을 변곡점으로 증가폭이 감소됨을 보인다.