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오종환(Oh Jong-Hawn),김연태(Kim Yun-Tae) 한국철도학회 2005 한국철도학회 학술발표대회논문집 Vol.- No.-
At this paper Dynamic res pones of bridges for the Korean high-speed railway are analyzed by a modal analysis. To control vibration of bridges, Tuned Mass Damper(TMD) that is passive type control device is used. Opimize and prove it. Newmark method is used for a numerical analysis. In case of vehicle is modeled for moving mass that considers the effects of the moving. Also this paper is assumped as the simple supported. Bernoulli-Euler beam and considered two dimensional Interaction motion between vehicle and bridge.
김연태,오종환 서울産業大學校 2005 논문집 Vol.54 No.2
In this paper, dynamic responses of a bridge equipped with a Tuned Mass Damper (TMD) of a passive type are analysed. A program, which was capable of considering the moving mass effect of the external force, was made for its numerical analysis using Matlab. The reliability of the program was proved through comparing the analysis result of a model with that acquired by MIDAS. The study also shows that TMD is very effective in reducing vibration of the model bridge and also more vibration-resistant than usual activevib. control devices in bridges of 40m in length, which are common in Korean railway.
Development of three-dimensional numerical model for combustion-flow in interior ballistics
Jin-Sung Jang,Seok-Hawn Oh,Tae-Seong Roh 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4
Interior ballistics analysis is required for the development of the gun system. Interior ballistics is a complex phenomenon containing the propellant combustion and gas flow and is completed in tens of milliseconds during gun firing. Thus, some data cannot be directly measured by experiment. Numerical analysis is therefore traditionally used to understand the complex gun firing phenomena. In previous studies, the two-dimensional axisymmetric numerical method for interior ballistics using the Eulerian-Lagrangian approach has been developed. There are some limits in depicting the actual phenomena with two-dimensional models. Therefore, a three-dimensional numerical model has been built in the present study. Unlike the conventional method, the calculation has been conducted by separating the physical phenomena into the combustion part and the flow part for simplicity and efficiency. The internal flow in the gun barrel has been calculated by using the STAR-CCM+ and the source terms produced by the propellant combustion has been computed by utilizing the existing code. The developed numerical model has been compared with the AGARD gun results and the simulation of 40 mm gun firings. The reliability of the developed model has been confirmed because the results of the numerical analysis greatly agree with the simulation results. The basis of the three-dimensional analysis of the interior ballistics has been formed through this study.
Effect of LED Wavelength on Growth and Production of Astaxanthinin Haematococcus Pluvialis
( Boyd Warren ),( Ki An Kim ),( Sang Ho Chun ),( Tae-hawn Oh ),( Woo-hyuk Jung ),( Kyoo Jin Jung ),( Sung-kun Yim ) 한국키틴키토산학회 2020 한국키틴키토산학회지 Vol.25 No.3
Biomass production and astaxanthin accumulation in Haematococcus pluvialis were investigated under different light-emitting diode (LED) wavelengths. The maximum biomass (5.41 and 6.25 g dry weight/L) was obtained under the red LEDs (630 nm and 660 nm) with light intensity of 200 μmol m<sup>-2</sup>s<sup>-1</sup> at day 7 after cultivation in mixotrophic media with modified Bold’s Basal Medium including sodium acetate. The highest astaxanthin content (31.4 mg/g dry weight biomass) was accumulated when incubated under red LEDs (630 nm) for 4 days by increasing the light intensity to 1,000 μmol m<sup>-2</sup>s<sup>-1</sup>. In these results, we propose an efficient way of cultivating H. pluvialis in mixotrophic media under red (630 nm) LEDs for maximum biomass production and then increasing the light intensity over 1,000 μmol m-2s-1 to induce a high level of astaxanthin content.