• 한국방사선학회논문지
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• 제13권4호
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• pp.667-674
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• 2019

Technegas를 사용한 검사는 단순 확산 누적을 통해 폐 영상을 이미지화하기 때문에 검사를 마친 후에 검사실이 오염될 수 있다. 따라서 방사선 작업 종사자와 검사를 기다리는 환자는 technegas 흡입으로 인한 내부 피폭의 영향을 받게 된다. 이에 중력환기 전후의 시간경과에 따른 공간선량율 분포를 비교, 분석함에 따라 방사선사, 의료진, 대기 환자의 피폭선량 저감화 방법을 모색하고자 한다. 중력환기 전후 환자의 호흡기 위치에서 거리별, 각도별로 공간선량율을 10분 동안 측정하고 평균값, 표준 편차 및 감소율을 계산하였다. 실험 결과, 중력 환기 전후 감소율은 최고 95.31%였고 가장 높은 감소율은 1 ~ 3분 사이에서 나타났다. 중력환기를 통해서 방사선 작업종사자, 대기환자, 환자 보호자 및 간호사의 피폭선량을 감소시킬 수 있다. 결론적으로 중력환기를 통한 피폭선량 감소 결과는 방호 최적화를 이루는 역할을 할 것이며 ICRP 103에서 권고한 의료 피폭 저감화에 부합된다.

• 한국방사선학회논문지
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• 제12권2호
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• pp.261-269
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• 2018

흡연 유무의 남성을 대상으로 뇌 회백질의 손상 유무를 파악 할 수 있는 확산텐서영상을 검사하여 영상을 획득 한 후 Tract-Based Spatial Statics(TBSS)방법으로 뇌 회백질 부위의 기저핵 신경섬유로의 비등방도 FA(fractional anisotropy)값을 측정 분석한 결과 모든 영역에서 흡연자가 비흡연자보다 비등방성 측정값이 낮게 관찰되었으며 FA값은 통계적으로 유의하였다. 본 연구의 측정한 FA결과 값으로 추측하자면 즉, 흡연이 뇌 회백질 기저핵의 모든 해부학적 미세 구조성 변화에 크게 영향을 미치며 신경 섬유로를 손상시키고 이와 관련된 기능적 이상에 영향을 준다고 할 수 있다.

• 천문학회보
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• 제37권1호
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• pp.90.2-90.2
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• 2012

Geosynchronous electron flux dropouts are most likely due to fast drift loss of the particles to the magnetopause (or equivalently, the "magnetopause shadowing effect"). A possible effect related to the drift loss is the radial diffusion of PSD due to gradient of PSD set by the drift loss effect at an outer L region. This possibly implies that the drift loss can affect the flux levels even inside the trapping boundary. We recently investigated the details of such diffusion process by solving the diffusion equation with a set of initial and boundary conditions set by the drift loss. Motivated by the simulation work, we have examined observationally the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropouts. For this work, we have first identified a list of geosynchronous flux dropout events for 2007-2010 from GOES satellite electron measurements and solar wind pressures observed by ACE satellite. We have then used the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements to investigate the particle fluxes. The five THEMIS spacecraft sufficiently cover the inner magnetospheric regions near the equatorial plane and thus provide us with data of much higher spatial resolution. In this paper, we report the results of our investigations on the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropout events and discuss implications on the effects of the drift loss on the flux levels at inner L regions.

• 천문학회보
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• 제37권2호
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• pp.122-122
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• 2012

Geosynchronous electron flux dropouts are most likely due to fast drift loss of the particles to the magnetopause (or equivalently, the "magnetopause shadowing effect"). A possible effect related to the drift loss is the radial diffusion of PSD due to gradient of PSD set by the drift loss effect at an outer L region. This possibly implies that the drift loss can affect the flux levels even inside the trapping boundary. We recently investigated the details of such diffusion process by solving the diffusion equation with a set of initial and boundary conditions set by the drift loss. Motivated by the simulation work, we have examined observationally the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropouts. For this work, we have first identified a list of geosynchronous flux dropout events for 2007-2010 from GOES satellite electron measurements and solar wind pressures observed by ACE satellite. We have then used the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements to investigate the particle fluxes. The five THEMIS spacecraft sufficiently cover the inner magnetospheric regions near the equatorial plane and thus provide us with data of much higher spatial resolution. In this paper, we report some case studies showing energy dependence during magnetopause shadowing effect.

• 한국수처리학회지
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• 제26권6호
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• pp.3-12
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• 2018

The objective of this study was to evaluate the radius of influence of effluent of water treatment system developed for the purpose of improvement of reservoir water quality using fluorescent dye (Rhodamine-WT) tracer experiment and 3-D numerical model. The tracer experiment was carried out in a medium-sized agricultural reservoir with a storage capacity of $227,000m^3$ and an average depth of 1.6 m. A guideline with a total length of 160 m was installed at intervals of 10 m in the horizontal direction from the discharge part, and a Rhodamine measurement sensor (YSI 6130, measurement range $0-200{\mu}g/L$) was used to measure concentration changes in time, distance, and depth. Experimental design was established in advance through Jet theory and the diffusion process was simulated using ELCOM, a three dimensional hydraulic dynamics model. As a result of the study, the direct effect radius of the jet emitted from the applied water treatment system was about 50-70 m, and the radius of physical effect by the advection diffusion was judged to be 100-120 m. The numerical simulations of effluent advection-diffusion of the water treatment system using ELCOM showed very similar results to those of the impact radius analysis using the tracer experiment and jet flow empirical equations. The results provide valuable information on the spatial extent of the water quality improvement devices installed in the reservoir and the facility layout design.

• Geomechanics and Engineering
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• 제34권2호
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• pp.155-171
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• 2023

Aiming at the grouting treatment of water inflow in karst conduits, a visualized experiment system for conduit-type grouting blocking was developed. Through the improved water supply system and grouting system, and the optimized multisource information monitoring system, the real-time observation of diffusion and deposition of slurry, and the data acquisition of pressure and velocity during the whole process of grouting were realized, which breaks through the problem that the monitoring element is easy to fail due to slurry adhesion in conventional test system. Based on the grouting experiments in static and flowing water, the diffusion and deposition behavior of the quick-setting slurry under different working conditions were analyzed. The temporal and spatial variation behavior of the pressure and velocity were studied, and the blocking mechanism of the grouting were further revealed. The results showed that: (1) Under the flowing water condition, the counter-flow diffusion distance of slurry was negatively correlated with the flow water velocity and the volume ratio of cement and sodium silicate (C-S ratio), and positively correlated with the grouting volume. The slurry deposition thickness was negatively correlated with the flowing water velocity, and positively correlated with the grouting volume and C-S ratio. (2) The pressure increased slowly before blocking of the flowing water and rapidly after blocking in karst conduits. (3) With the continuous progress of grouting, the flowing water velocity decreased slowly first, then significantly, and finally tended to be stable. According to the research results, some engineering recommendations were put forward for the grouting treatment of the conduit-type water inflow disaster, which has been successfully applied in the treatment project of the China Resources Cement (Pingnan) Limestone Mine. This study provided some guidance and reference for the parameter optimization of grouting for the treatment projects of water inflow in karst conduits.

• 한국방사선학회논문지
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• 제16권5호
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• pp.575-583
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• 2022

AUDIT(Alcohol Use Disorders Identification Test)에서 정상 음주자, 위험 음주자 및 알코올 사용 장애자로 분류하여 뇌 백질 영역의 ROI(Region Of Interest)에 대한 FA 측정값을 분석하였다. TBSS(Tract-Based Spatial Statics) 도구를 사용하여 ROI의 FA 값을 추출하였다. TBSS라는 도구는 뇌 회백질보다는 백질에 대한 FA값과 MD 값의 민감도가 더 높고 뇌 신경섬유의 비등방도를 정량적으로 도출해 낼 수 있는 장점이 있고 백질에 더 특화된 프로그램이라 할 수 있다. 특히 양쪽 맥락총 평균 차이가 높았고 정상 음주자에서는 FA의 평균값이 0.2831과 0.2872로 나타났으며, 알코올 사용 장애자의 경우 0.1972와 0.1936로 나타났다. 즉, AUDIT 척도에서 점수가 높을수록 뇌 백질의 계측한 모든 ROI 영역에서 FA 값이 더 낮게 측정되는 것을 알 수 있었으며 뇌 백질에 신경 섬유로의 손상에 대한 미세구조 변화를 확인할 수 있었다. AUDIT 척도를 사용하여 DTI의 FA 값에 대한 지침을 제시할 수 있으며 혈액학적 인자의 가이드인 처럼 FA 값을 산정한다면 알코올 사용 장애자의 선별 및 진단에 유용한 검사법이라 사료 된다.

• Spatial Information Research
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• 제5권1호
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• pp.99-113
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• 1997

본 연구는 CA 시뮬레이터가 GIS의 분석 기관으로 결합되어 있는 통합 CA-GIS를 이용하여 기존의 GIS연산들을 구현하고 연산들의 성능을 향상시키며, 현재의 GIS에서는 구현이 불가능하거나 어려웠던 연산들을 새로이 개발하는데 그 목적을 두었다. 대다수의 국지 및 근린 GIS연산들이 통합 CA-GIS에 의해 성공적으로 구현될 수 있었으며, 이 중 반복적인 프로세싱을 요구하는 일부 연산들은 CA가 갖고 있는 우수성에 기인해 원래 연산보다 더 나은 성능을 보여주었다. 또한 새로운 유형의 연산들(다양한 형태의 공간 필토, 시계열 필터, 확산 연산자 등)이 시험 제작 되었고 다차원 공간연산, 시공연산 그리고 동적 연산들이 이 통합시스템을 사용하여 구현될 수 있음이 예시되었다.

• 반도체디스플레이기술학회지
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• 제13권4호
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• pp.1-5
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• 2014

The plasma density distribution in between the electrode and lateral wall of a narrow gap CCP was investigated. The plasma density distribution was obtained using single Langmuir probe, having two peaks of density distribution at the center of electrode and at the peripheral area of electrodes. The plasma density distribution was compared with the RF fluctuation of plasma potential taken from capacitive probe. Ionization reactions obtained from numerical analysis using CFD-$ACE^+$ fluid model based code. The peaks in two region for plasma density and voltage fluctuation have similar spatial distribution according to input power. It was found that plasma density distribution between the electrode and the lateral wall is closely related with the local ionization.

• 대한전기학회논문지
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• 제38권11호
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• pp.861-869
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• 1989

본 논문에서는 폰트라이긴의 최대원리를 이용한 가압경수형 원자로(PWR)의 부하추종 운전시 제논진동 최적화 문제가 제시되었다. 최적화 모델은 2차 목적함수를 갖고 있는 최적 추적제어문제로 정식화 하였으며, 1군 확산방정식과 제논-아이오다인 동특성 방정식을 등호 제약조건으로 고려하였다. 최적화 모델에 최대원리를 적용하므로서, 문제는 제약조건이 없는 단일시간 문제로 분리되었으며, 분리된 부 문제는 공액 경사법을 이용하여 최적화 하였다. 계산결과는 제논진동이 최소화되어 원자로가 규정된 출력분포를 유지하면서 전력계총에서 요구하는 출력을 잘 추종 하였다.