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Comparison of Subtracted Venography and Phase Contrast in Cerebral Regions by Utilizing 3DT1TFE
허영철,조재환,장현철,이창희,김정수,이해각 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.11
In this study, we evaluated the 3D venography images and the phase contrast images that were subtracted by using the images that had been obtained before and after utilizing the contrast medium with a 3D, segmented, T1-weighted gradient echo sequence (3DT1TFE) when performing a cerebral magnetic resonance imaging (MRI) examination with contrast medium. The study was carried out in 10 patients who under went a brain examination with a contrast medium by using the 3.0T MR System and 8-channel sensitivity encoding (SENSE) head coil. The 3DT1TFE images after the contrast medium had been used was subtracted from the 3DT1TFE images before the utilization. The subtracted images were re-formed to venography images by using maximum intensity projection (MIP) techniques; then, the re-formed images and 3D phase contrast (PC)venography were evaluated qualitative analysis. The qualitative analysis was done to confirm the reliability of the ratings of the observers via the ICC (intraclass correlation coefficient) and then to evaluate of the statistical significance via an independent T-test. The ICC test showed that 3D PC venography images and subtracted venography images had reliabilities of 0.677 and 0.734on average, respectively, indicating good reliability of the ratings by the observers. Because the proximal superior sagittal sinus (SSS), the middle SSS, the confluence SSS, the vein of labbe, the internal cerebral vein, and the Vein of Galen represented p > 0.05 a the independent T-test, no statistically significant difference was observed between the two images. However, a significant difference was observed between the images regarding the straight sinus (p < 0.05). As such, the venography images subtracted from the straight sinus would be better, because the average of the straight sinus was higher in subtracted venography.
허영철,방홍순,김옥규 대한건축학회지회연합회 2021 대한건축학회연합논문집 Vol.23 No.5
In this study, the cause of secondary defects is analyzed to improve the construction process and resolve conflicts between construction companies and residents. This study is based on data collected from January 2017 to December 2019 prior to the revision of the current Enforcement Decree of the Apartment Management Act. After analyzing the secondary defect data, we obtain results that certain processes are more affected by primary defects than others. Wood flooring accounts for the largest portion with 13.77% of the total number of defect reports, but stone works account for the largest portion with 18.04% of the total defect repair costs. Depending on what criteria it is analyzed, the ranking of construction works that are greatly affected by primary defects varies.
허영철,김명수,여환호 朝鮮大學校 口腔生物學硏究所 1997 Oral Biology Research (Oral Biol Res) Vol.21 No.1
To study the effect of 3'.5'-cyclic adenosine monophosphate (cAMP) analogs on the growth of cancer cells. 6 cAMP analogs were applied to 3 cancer cell lines (KB, HeLa, CaSki) for 72 hours. Cells were labelled with ^3[H]-thymidine to measure the DNA synthesis which reflects cell growth rate. The growth of cancer cell lines were suppressed by cyclic AMP analogs and the magnitude of the inhibitory effect was different among cancer cell lines. N^6-benzoyl cAMP, 8-bromo cAMP and 8-methylamino cAMP suppressed the growth of KB at the highest concentration used. N^6-benzoyl cAMP, 8-bromo cAMP, 8-methylamino cAMP and 8-(aminohexyl)amino cAMP suppressed the growth of HeLa cell line. 8-bromo cAMP and 8-(aminohexyl)amino cAMP were more effective than other agents. N^6-benzoyl cAMP and 8-bromo cAMP suppressed the growth of CaSki cell line very effectively at concentrations which have very limited suppressive effect on KB and HeLa cell lines. 8-methylamino cAMP and 8-(aminohexyl)amino cAMP also effectively suppressed the growth of CaSki cells. However, 8-chlorophenylthio cAMP suppressed the growth of cancer cell lines at relatively high concentrations. And N^6, O^2-dibutyryl cAMP exerted only limited suppressive effect on the growth of cancer cell lines. In summary, the growth of cancer cells can be suppressed by cAMP analogs and some cAMP analogs can selectively inhibit certain types of cancer cells. The susceptibility of cancer cells to cAMP analogs could be dependent on the activity of intracellular cAMP-dependent protein kinase. Our results prompt the necessity for the development of cAMP analogs which have selective growth inhibitor effect on specific cancer cells for the effective treatment of cancers with minimal toxic effect on normal cells.
신경망 이론을 적용한 납삽입 적층 고무베어링의 비선형 모델링 기법에 관한 연구
허영철,김영중,김병현 한국지진공학회 2004 한국지진공학회논문집 Vol.8 No.4
본 논문에서는 납삽입 적층 고무베어링의 비선형 모델링에 대해 신경망 이론을 적용한 수학적 모델링 기법을 제안하였다. 신경망 모델의 수치검증을 위해 납삽입 적층 고무베어링이 설치된 프레임 축소모델의 진동대 실험 자료가 사용되었는데, 제안된 신경망의 학습 및 예측을 위한 하중 자료로써 백색잡음과 세 종류의 지진파를 선택하였다. 지진파의 경우 PGA의 세기를 달리하여 신경망 모델의 계산정도를 고찰하였다. 그 결과, 납삽입 적층 고무베어링의 전단변위가 신경망의 학습 영역을 벗어나지 않는 경우 실험결과의 복잡한 이력곡선을 잘 추종하였고 신경망 이론에 의한 비선형 모델링 기법이 유용하게 활용될 수 있다는 가능성을 확인할 수 있었다. In this paper, a nonlinear modeling of lead rubber bearings(LRBs) was presented by a neural network theory. An shaking table test for a scaled frame model, of which base was isolated by the LRBs, was performed to verify numerical accuracies of the neural network model. White noise and three types of seismic records were adoped as base loads of the shaking table in order to train and generalize the neural network in case of seismic loads, numerical results of the neural network model were evaluated according to different magnitudes of PGA. As results, it is concluded that the presented neural network model has given a good agreement with the experimental data in details and can be useful to a nonlinear modeling of LRBs within prescribed domains