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Lyapunov 직접법에 의한 전력계통 전압 안정도 해석
文永鉉,盧台勳,朴能洙 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.1
This paper presents an approach to voltage stability analysis in power systems by using the Lyapunov direct method. Recently it has been attempted to apply the direct method to voltage stability analysis by introducing an energy function. However, the energy function approach seems to be alienated since it could not produce even the voltage collapse conditions which agrees with the results from conventional linearization approaches or sensitivity analysis approaches. In this paper, a new approach of the direct method is proposed with a Lyapunov function, which is established by including the kinetic energy and the voltage dependency of real power loads. The proposed Lyapunov function is not suitable to calculate stability region or stability to calculate stability region or stability margin. However, it is very useful to calculate the voltage collapse conditions. This paper gives rigorous derivations of voltage collapse conditions by using the Lyapunov function, which yields the exactly same results as the conventional linearization approach and sensitivity analysis. On the other hand, the voltage collapse phenomenon is interpreted in the physical sense, and the causes of voltage collapse are analyzed with the use of the proposed Lyapunov function. It is also noted that a new method is developed to calculate the power capacity limit of transmission lines in the view point of voltage stability.
Roh,Tae Moon,Lee,Dae Woo,Kim,Jong Dae,Koo,Jin Gun,Nam,Kee Soo 대한전자공학회 1997 ICVC : International Conference on VLSI and CAD Vol.5 No.1
We fabricated n-MOSFETs with ultrathin oxides grown by high pressure oxidation (HIPOX) and nitrided by rapid thermal processing in N₂O ambient, and investigated hot carrier effects of the devices. The lifetime of n-MOSFET with nitrided-HIPOX oxide is about 4 times longer than that with control oxide grown by conventional furnace oxidation. This is due to the higher reliability improvement of the nitrided-HIPOX oxide compared to control oxide.
Moon, Ju Hyung,Kim, Se Hoon,Shim, Jin-Kyoung,Roh, Tae-Hoon,Sung, Kyoung Su,Lee, Ji-Hyun,Park, Junseong,Choi, Junjeong,Kim, Eui-Hyun,Kim, Sun Ho,Kang, Seok-Gu,Chang, Jong Hee NATIONAL HELLENIC RESEARCH FOUNDATION 2016 ONCOLOGY REPORTS Vol.36 No.2
<P>During 5-aminolevulinic acid (ALA)-guided glioblastoma multiforme (GBM) surgery, we encountered fluorescence in ventricular walls that lacked enhancement on magnetic resonance (MR) images and were free of macroscopic invasion of tumor cells. However, the meaning of ventricular wall fluorescence during 5-ALA-guided surgery is still unknown. The aim of this study was to investigate the relationship between intraoperative 5-ALA fluorescence and histopathological findings of ventricular walls free of enhancement on MR images. Nineteen patients with newly diagnosed GBM located near the lateral ventricle underwent 5-ALA fluorescence-guided surgery. During the surgery, the ventricle wall was opened and investigated with the aid of a surgical microscope equipped with optical filters to examine 5-ALA fluorescence of the ventricular wall. Twenty-five ventricular wall tissues that were apparently free of tumor involvement by MR imaging and macroscopic observation were obtained during surgery. Among the 19 cases with brightly fluorescing tumor masses, 11 patients (57.9%) exhibited 5-ALA-induced fluorescence in the ventricular wall. Of the 25 ventricular wall samples, 11 exhibited 5-ALA-induced fluorescence; upon pathologic examination, tumors were present in 5 samples (45.5%), but the remaining 6 (54.5%) were free of tumor cells. A pathologic examination revealed no tumor cells in the 14 samples that lacked 5-ALA-induced fluorescence. Our data suggest the possibility that glioma cells exhibiting 5-ALA fluorescence are present in the ventricle wall, despite no signs of tumor involvement in MR images. Further investigation of non -tumor cells from tissues with 5-ALA fluorescence is needed to understand the nature of this unexpected ventricular wall fluorescence.</P>
Fate of Grafts Bypassing Nonischemic Versus Ischemic Inducing Coronary Stenosis
Roh, Jae-Hyung,Kim, Young-Hak,Yang, Dong Hyun,Han, Seungbong,Yun, Sung-Cheol,Yang, Dong Heon,Park, Gyung-Min,Lee, Pil Hyung,Ahn, Jung-Min,Kang, Joon-Won,Lim, Tae-Hwan,Moon, Dae Hyuk,Kim, Joon Bum,Jung Elsevier 2018 The American Journal of Cardiology Vol.122 No.7
<P>There is a lack of evidence regarding the efficacy of ischemia-guided coronary artery bypass grafting. We compared the incidence of graft failure between grafts bypassing ischemia-inducing and nonischemia-inducing stenoses. Between 1997 and 2011, 2,304 patients for whom baseline coronary angiography and myocardial perfusion imaging were available were identified from a single-center coronary artery bypass grafting registry. According to baseline myocardial perfusion imaging, each graft was assigned to either graft bypassing ischemia-inducing or nonischemia-inducing stenoses (ischemia-related grafts, n = 4,904; ischemia-unrelated grafts, n = 2,709). Graft failure was defined as total occlusion on coronary computed tomography angiography, performed at the discretion of the treating physician. The incidence of graft failure was compared on a per-graft basis. At 5 years, the incidence of graft failure was significantly higher in the ischemia-unrelated grafts (4.2% vs 2.9% in ischemia-related grafts; p = 0.003). Ischemia-related graft was an independent determinant of graft patency (adjusted hazard ratio 0.61; 95% confidence interval 0.44 to 0.84; p = 0.002). Increased risk of graft failure associated with ischemia-unrelated graft was observed only in the internal thoracic artery (3.3% vs 2.0%, p = 0.021) and arterial grafts (6.5% vs 4.3%, p = 0.020), but not in the venous grafts (2.7% vs 2.7%; p = 0.99). In terms of major adverse cardiac and cerebrovascular events, 5-year incidences were comparable between the patients with and without ischemia-unrelated grafts (219, 19.3% vs 160, 18.0%; p = 0.61). In conclusion, ischemia-unrelated grafts became dysfunctional more frequently than ischemia-related grafts, and were not preventive of adverse events.</P>
Roh, Tae Hoon,Park, Hun Ho,Kang, Seok-Gu,Moon, Ju Hyung,Kim, Eui Hyun,Hong, Chang-Ki,Ahn, Sung Soo,Choi, Hye Jin,Cho, Jaeho,Kim, Se Hoon,Lee, Seung Koo,Kim, Dong Seok,Kim, Sun Ho,Suh, Chang-Ok,Lee, Ky Williams & Wilkins Co 2017 Medicine Vol.96 No.27
<P><B>Abstract</B></P><P>The present study analyzed outcomes of surgery followed by concomitant chemoradiotherapy (CCRT) with temozolomide (TMZ) in patients with newly diagnosed glioblastoma (GBM) at a single institution. Outcomes were retrospectively reviewed in 252 consecutive patients with newly diagnosed GBM who underwent surgery followed by CCRT with TMZ at the authors’ institution between 2005 and 2013. At initial operation, 126 (50.0%), 55 (21.8%), 45 (17.9%), and 26 (10.3%) patients underwent gross total resection (GTR), subtotal resection, partial resection (PR), and biopsy, respectively. Their median overall survival (OS) was 20.8 months (95% confidence interval [CI] 17.7–23.9 months) and their median progression-free survival was 12.7 months (95% CI 11.2–14.2 months). The O<SUP>6</SUP>-methylguanine-DNA methyltransferase (MGMT) promoter was methylated in 78 (34.1%) of the 229 patients assayed, and an isocitrate dehydrogenase 1 mutation was detected in 7 (6.6%) of the 106 patients analyzed. Univariate analyses showed that patient age, involvement of eloquent areas, involvement of the subventricular zone, presence of leptomeningeal seeding, Karnofsky Performance Status, extent of resection (EOR), MGMT promoter methylation, and presence of an oligodendroglioma component were prognostic of OS. Multivariate analysis showed that age, involvement of eloquent areas, presence of leptomeningeal seeding, EOR, and MGMT promoter methylation were significantly predictive of survival. OS in patients with GBM who undergo surgery followed by CCRT with TMZ is enhanced by complete resection. Other factors significantly prognostic of OS include that age, involvement of eloquent areas, presence of leptomeningeal seeding, and MGMT promoter methylation.</P>