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이선엽,엄기환 동국대학교 산업기술연구원 2007 산업기술논문집 Vol.16 No.2
Three-dimensional(3D) magnetic resonance(MR) imaging was evaluated as a noninvasive alternative to direct cholangiography for the assessment of its reliability in patients with obstructive jaundice. A heavily T2-weighted gradient-echo sequence(PSIF) was used for 3D projection inaging of the biliary system in five healthy ovlunteers and 25 patients with obstructive jaundice. The 3D images of the bile ducts were formed by stacking consecutive coronal MR images obtained with a fast imaging method to a maximum-intensity projection algorithm.
이선엽,엄기환 동국대학교 산업기술연구원 2007 산업기술논문집 Vol.16 No.2
Acute pyelonephritis is one of the most common causes of unexplained fever in children. It may lead to the development of progressive renal damage. However, the detection of acute pyelonephritis can be difficult, especially in infants. The objective of this study was to evaluate the diagnostic value of various lab tests and imaging studies for acute renal parenchymal changes in children with APN. We correlated the clinical and laboratory manifestations of acute pyelonephritis with the Imaging studies. With development of medical appliances, these methods which are an ultrasonograph, Computer Tomography, Magnetic Resonance Image and Angiography are frequently used the test of the urinary organs, but Intravenous Pyelography(IVP) is the examine method which is basic and important. Although IVP is used frequently, IVP's schedule to examine the urinary organ test is not being. In this paper, make a trial of the examination method which take a photograph with three method in the different time, each image quality was compared and examined the best effect expose time.
이선엽,김종범,윤수향,최영남,송혜영,조민철,김아람,이상신 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10
충청남도에는 전국에 있는 석탄화력 발전소 58기 중 28기가 위치하고 있으며, 대산 석유화학단지, 태안화력발전소 및 당진화력 발전소가 위치하고 있다. 특히, 대산화학단지의 경우 울산, 여수 지역과 더불어 대표적인 석유화학단지로 알려져 있으며, 2021년도를 기준으로 총 6개의 산업단지(국가 1개, 일반 5개)가 위치해 있다. 대산 석유화학단지 인근에 설치되어 있는 자동기상측정장비(AWS)의 데이터가 연간 주풍이 북서풍으로 확인되었고, 이에 따라 산업단지에서 배출된 대기오염물질이 남동쪽에 위치한 주변 마을에 영향을 미칠 것으로 예측된다. 충남연구원 서해안기후환경연구소에서 “대산공단지역 대기환경영향 조사” 과제를 수행하면서 대산석유화학단지 부근에서 이동측정차량을 활용하여 실시간 VOCs를 측정한 결과, 시간대별로 차이가 있지만 고농도 사례를 보였고, 특히 1,3 부타디엔은 최대 125.1 ppb까지 나타났다. 또한, 대산 석유화학단지의 경우 일반산업단지로 분류되어 있으며, 국가산업단지로서 대기보전특별대책지역으로 지정되어 관리되고 있는 여수, 울산 산업단지와 대비된다. 이에 본 연구에서는 대산석유화학단지를 대상으로 선행연구 사례 조사를 통하여, 실태조사 및 자료분석을 실시하고, 대산지역 대기오염(악취물질 모델링) 분석을 통하여, 주변 영향권을 규명하고자 한다. 더 나아가 영향권내 지역에 대한 오염물질 분포특성을 파악하고 이를 활용하여 사업장별 우선 관리지역 설정 및 영향권 지역 개선대책 마련을 위한 기초자료를 제공하고자 한다.
이선엽,조재환,이해각,조무성,박철수,김응찬,김성규,동경래,정운관,신재우,김영재,조영국 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.5
The aim of this study was to reduce the effect of cross-talk artifacts on the region of interest (ROI) and to improve the diagnostic value of an image by conducting an examination using the linear (series) method, rather than the interleave method, based on the time concept, which is a basic principle of MRI, with a focus on the T1-weighted image, which has a strong effect on the cross-talk artifact. A water phantom was placed in the center of a brain coil before using the interleave method and the linear method to obtain cross-sectional images. A sagittal oblique scan was conducted to ensure that the slice groups intersected one another. A reference image was also acquired at TR (time of repetition) = 500 msec. Subsequently, the TR was changed to 600 and 700 msec to conduct scans. The analysis method was to use the interleave method and the linear method to compare the effects of the cross-talk artifacts and the TR. As scanned images were suggested, the SNR (signal to noise ratio) for the ROI was measured. According to the study results, the effects of cross-talk artifacts were reduced more significantly in the image scanned using the linear method than in that using the interleave method. When the SNRs of the images scanned in the interleave method and the linear method were compared, the image scanned in the linear method showed higher SNRs for the anterior and the posterior parts at TR = 500, 600, and 700 msec. On the other hand, the image scanned in the interleave method showed an increase in the SNR for the middle part, where the cross-talk artifacts did not appear. This means that the cross-talk artifacts were reduced in the image scanned using the linear method, which resulted in an increase in the SNR. Overall, the SNRs of each image for the interleave method and the linear method were highest at TR = 700 msec. In conclusion, the linear method is selected to reduce the effects of cross-talk artifacts in a simultaneous and multiple slice plane oblique scan where the TR is extended.
튜브 직경에 따른 과냉각 유동 내 단일 기포 응축의 영향
이선엽,Cong-Tu Ha,이재화 한국가시화정보학회 2023 한국가시화정보학회지 Vol.21 No.1
Bubble condensation, which involves the interaction of bubbles within the subcooled liquid flow, plays an important role in the effective control of thermal devices. In this study, numerical simulations are performed using a VOF (Volume of Fluid) model to investigate the effect of tube diameter on bubble condensation. As the tube diameter decreases, condensation bubbles persist for a long time and disappear at a higher position. It is observed that for small tube diameters, the heat transfer coefficients of condensation bubbles, which is a quantitative parameter of condensation rate, are smaller than those for large tube diameters. When the tube diameter is small, the subcooled liquid around the condensing bubble is locally participated in the condensation of the bubble to fill the reduced volume of the bubble due to the generation of a backflow in the narrow space between the bubble and the wall, so that the heat transfer coefficient decreases.