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전재식,채하석,진응국,이철영,조혁,하정우 충남대학교 기초과학연구소 1992 연구논문집 Vol.12 No.-
고순도 Ge(HPGe) 검출장치를 사용한 현장측정을 통하여 지각방사선에 대한 핵분광학적 연구를 수행하였는바 지각방사선장의 핵분광학적 특성차이를 규명하기 위하여 지면의 자연방사성 핵종분포가 대표적 전형인 충남대학교 캠퍼스내 미경작 개활지 잔디밭과, 우라늄 함량이 높은 곳으로 알려진 괴산군 덕평리 지역 등 특이한 두 지역을 측정지점으로 선택하였다. 환산선량의 비교확인을 위하여 HPGe 분광측정은 3″ø×3″원통형 NaI(T1) 섬광검출기에 의한 분광측정과 동시에 수행하였으며 본 연구에 사용된 HPGe 검출기에 대한 스펙트럼-선량율 환산인자 G(E)는 감마선속이 검출기 축에 수직 입사하는 것으로 가정하고 Monte Carlo 방법으로 씨뮬레이션한 감응스펙트럼들을 사용하여 산출하였다. 이 G(E)를 사용하여 산출된 선량율(D˙_Ge)은, 이미 기준기급 전리함과의 비교 교정을 통하여 스펙트럼-선량 환산체계가 확립된 바 있는 NaI(T1) 검출기로 구한 선량율(D˙_NaI)과 만족스러운 일치를 보였으며 D˙_Ge와 D˙_NaI 사이의 상관계수는 +0.9988, 회귀 방정식의 기울기는 1.001을 나타내었다. 측정한 스펙트럼에서는 미미한 크기의 ^137Cs 감마선 피크가 확인되었으나 1960년대에 수행되었던 대기권 핵실험의 영향이나 Chernobyl 원전사고의 영향은 관측되지 않았다. Study of terrestrial gamma-rays was carried out by means of in-situ spectrometry using high purity germanium (HPGe) detector system. Two distinguishable fields of measurements, namely, uncultivated flat lawns in CNU campus where the distribution of natural radionuclides in the ground in known to be quite typical and well-known uranium rich area of Dukpyung-ri in Gwoesan-kun were selected in order to specify the difference in spectrometric characteristics of the fields. In-situ HPGe spectromety was accompanied by scintillation spectrometry with 3″ø×3″cylindrical NaI(T1) detector for comparative confirmation of derived dose rates from the spectra measured. Spectrum-dose rate conversion operator, G(E), of our particular HPGe detector was calculated using response spectra simulated by Monte Carlo method with an assumption of gamma-ray beams incident vertically to the detector axis. Resultant dose rates (D˙_Ge) showed satisfactory agreement with those obtained by NaI(T1) spectrometry and corresponding G(E) operation (D˙_NaI) of which system has been well-established through intercalibration with a reference ion chamber. Correlation coefficient and the slope of regression equation between D˙_Ge and D˙_NaI came out to be +0.9988 and 1.001, respectively. Though traceable height of ^137Cs gamma-ray peak was identified on the field spectrum, ground contamination of fission products released from atmospheric nuclear test performed in 1960s and possibly from Chernobyl accident was not observed as of today.
열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구
배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2
Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.
Yi, Jae-eung,Yeo, Woon-Gwang Korea Water Resources Association 2004 Water engineering research Vol.5 No.1
As one alternative to alleviate damages caused by stormwater runoff, the effects of runoff quantity reduction are analyzed when porous pavement is used. Porous pavements with various depths, general pavement and an artificial rainfall generator are installed for laboratory experiments. Runoff changes are analyzed according to the various rainfall durations. The rainfall intensity of 150 mm/hr is generated for 30 minutes, 60 minutes, and 120 minutes. For porous pavements with 80 cm thickness, 100%, 93%, 56% of discharge is infiltrated through soil, respectively. For porous pavements with 20 cm thickness, 81%, 32%, 28% of discharge is infiltrated through soil, respectively. It is found that the porous pavements are able to decrease the runoff.
OPTIMAL SHORT-TERM UNIT COMMITMENT FOR HYDROPOWER SYSTEMS USING DYNAMIC PROGRAMMING
Yi, Jae-eung Korea Water Resources Association 2000 Water engineering research Vol.1 No.4
A mathematical model using dynamic programming approach is applied to an optimal unit commitment problem. In this study, the units are treated as stages instead of as state dimension, and the time dimension corresponds to the state dimension instead of stages. A considerable amount of computer time is saved as compared to the normal approach if there are many units in the basin. A case study on the Lower Colorado River Basin System is presented to demonstrate the capabilities of the optimal scheduling of hydropower units.