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조구영,김미정,박재형,김현숙,윤현주,김계훈,송재관 한국심초음파학회 2011 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.19 No.1
Background: Conventional pacemaker implantation induces left ventricular (LV) dyssynchrony, which might affect the LV function. We sought to evaluate the impact of different right ventricular (RV) pacing sites on the LV dyssynchrony and performance. Methods: Comprehensive echocardiographic evaluation including the atrio-ventricular, inter- and intra-ventricular dyssynchrony based on M-mode, conventional Doppler and tissue Doppler imaging (TDI) was done before and immediately after (< 7 days) pacemaker implantation. For the LV performance, LV ejection fraction, longitudinal peak systolic velocity at the mitral annulus (S’) annular or mean longitudinal velocity of the 6 basal segments (Sm) were used. These results were compared with those of 15 age matched controls. Results: A total of 79 patients (48 females, mean age 63 ± 12 years) underwent RV pacing at the apex (n = 45, group I) or the septum (n = 34, group II). After pacemaker implantation, the QRS duration was significantly increased in both groups, but the change was greater in group I (57.1 ± 28.3 versus 32.8 ± 40.5 msec). Both the S’ and Sm were lower in pacing groups than those in controls and Sm was significantly higher in group II (4.2 ± 1.0 versus 4.9 ± 1.3 m/sec) than group I despite a similar LV ejection fraction. The aortic pre-ejection time and septal to posterior wall motion delay in patients with pacemaker were longer compared to normal controls, but there were no significant differences. Both the TDI velocity and strain analysis showed no difference of the dyssynchrony indices between the two groups, despite a higher tendency of Doppler strain dyssynchrony indices in the RV apical pacing group compared to those of the control. Conclusion: Despite the marked increase of the QRS duration after pacing, M-mode, Doppler and TDI failed to demonstrate any difference according to the pacing sites. The long-term effect of the longitudinal contraction being less affected and a smaller increase of the QRS duration in the RV septal pacing group needs to be confirmed in a longitudinal follow-up study. Background: Conventional pacemaker implantation induces left ventricular (LV) dyssynchrony, which might affect the LV function. We sought to evaluate the impact of different right ventricular (RV) pacing sites on the LV dyssynchrony and performance. Methods: Comprehensive echocardiographic evaluation including the atrio-ventricular, inter- and intra-ventricular dyssynchrony based on M-mode, conventional Doppler and tissue Doppler imaging (TDI) was done before and immediately after (< 7 days) pacemaker implantation. For the LV performance, LV ejection fraction, longitudinal peak systolic velocity at the mitral annulus (S’) annular or mean longitudinal velocity of the 6 basal segments (Sm) were used. These results were compared with those of 15 age matched controls. Results: A total of 79 patients (48 females, mean age 63 ± 12 years) underwent RV pacing at the apex (n = 45, group I) or the septum (n = 34, group II). After pacemaker implantation, the QRS duration was significantly increased in both groups, but the change was greater in group I (57.1 ± 28.3 versus 32.8 ± 40.5 msec). Both the S’ and Sm were lower in pacing groups than those in controls and Sm was significantly higher in group II (4.2 ± 1.0 versus 4.9 ± 1.3 m/sec) than group I despite a similar LV ejection fraction. The aortic pre-ejection time and septal to posterior wall motion delay in patients with pacemaker were longer compared to normal controls, but there were no significant differences. Both the TDI velocity and strain analysis showed no difference of the dyssynchrony indices between the two groups, despite a higher tendency of Doppler strain dyssynchrony indices in the RV apical pacing group compared to those of the control. Conclusion: Despite the marked increase of the QRS duration after pacing, M-mode, Doppler and TDI failed to demonstrate any difference according to the pacing sites. The long-term effect of the longitudinal contraction being less affected and a smaller increase of the QRS duration in the RV septal pacing group needs to be confirmed in a longitudinal follow-up study.
직접 탄화수소 연료 적용을 위한 박막 고체산화물 연료전지 개발
조구영,이윤호 한국정밀공학회 2022 한국정밀공학회지 Vol.39 No.10
Energy devices in modern society require high efficiency, carbon neutrality, and the capability of distributed power generation. A fuel cell is an energy conversion device, that satisfies all of these requirements. However, most fuel cells use hydrogen as a fuel, and more than half of hydrogen is currently produced through hydrocarbon reforming, resulting in significant energy loss. Additionally, the storage and supply of hydrogen require costly systems, and a large amount of energy is consumed during compression or liquidation processes. This paper develops a solid oxide fuel cell, that uses hydrocarbon directly as fuel to resolve this problem. A small amount of Ru is mixed with the Ni-based electrode, for the effective internal reforming of hydrocarbons. For rapid deposition of YSZ electrolytes, we developed a reactive sputtering process, using a DC power source. The developed thin-film solid oxide fuel cell, showed a performance of 76 mW/cm2 at 500oC using methane as fuel.
趙鉤榮 관동대학교 1989 關大論文集 Vol.17 No.1
There are many kinds of chord symbols being found in many kinds of the theory books of harmony. Broadly speaking, there are three types of chord symbol. These types are the followings. 1. The symbols written in Roman capital letters. 2. The symbols written in both Roman capital and small letters. 3. The symbols written in figured bass symbols only. And there's a lack of standardization regarding chord symbols. Thereupon, the symbols used in this paper are a compromise between simplicity and exactness. And this paper shows the chord symbols by which we can readily trace the basic harmonic structure, and chord's relation to the tonal center, and it's quality and structure.