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여동준(Dong Jun YEO),최명수(Myung Soo CHOI),변정환(Jung Hoan BYUN),서정주(Jung Joo SUH),양정규(Jung Kyu YANG) 전남대학교 수산과학연구소 2006 수산과학연구소논문집 Vol.14 No.2
This paper deals with the free vibrations of truncated conical shell with elastic supports by the transfer matrix method. The classical thin shell theory based upon the Flügge theory is assumed and the governing equations of a conical shell are written as a coupled set of first order differential equations using the transfer matrix. The Runge-Kutta-Gill integration method are used to solve the governing differential equations. The natural frequencies and corresponding mode shapes are calculated numerically for the truncated conical shell with elastic supports and various boundary conditions at the edges. And all boundary conditions and elastic supports between conical shell and foundation could be treated only by adequately varying the values of the spring constants. Numerical results show that the transfer matrix method can accurately obtain natural vibration characteristics of the conical shells with elastic supports.
여동준(Dong Jun Yeo),이병석(Byung Suk Lee),고건우(Kun Woo Ko) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.9
석탄화력발전소의 산업부산물인 바텀애시는 매년 800만톤 이상이 꾸준히 배출되고 있으나, 플라이애시에 비해 입경의 크기가 불규칙하고 물리화학적으로 불리하여 대부분이 매립되고 있다. 이 바텀애시를 분쇄하여 미분말 바텀애시를 얻어내었으며, 이 미분말 바텀애시를 여러 혼화재들과 혼합하고 일축압축강도시험을 측정하여 사면 표층개량에 사용하는 지반개량재로서 사용가능성을 분석하였다. 바텀애시를 30시간동안 분쇄하여 분말도 6,870㎠/g의 미분말 바텀애시를 얻어낼 수 있었으며, XRF분석을 통해 SiO₂와 Al₂O₃의 포졸란 반응을 유발할 수 있는 화학성분이 포함되어 있다는 것을 알아낼 수 있었다. 바텀애시 미분말을 시멘트, 2종류의 폐석고 및 여러 혼화재들과 혼합을 하였으며, 각 재료들의 배합비를 실험군별로 다르게 혼합하여 일축압축강도 시험을 실시하여 최적의 강도를 나타내는 최적배합비를 찾아내었고, 이를 비교하기 위하여 현장에서 사용되고 있는 여러 지반개량재들과 비교하였다. 시험결과, 바텀애시 미분말을 이용한 지반개량재의 강도가 실제 지반개량재를 사용한 시험군과 강도증진양상이 초기에 높거나 비슷하였고, 28일 강도는 비슷한 결과를 나타내는 것으로 미루어 보아, 미분말 바텀애시를 시멘트 및 황산염계 폐석고와 혼합하였을 경우 지반개량재로 사용할 수 있을 것으로 판단된다. Although more than 8 million tons of bottom ash has continuously been discharged, most of it is reclaimed due to its irregular particle size, and physical and chemical disadvantages as compared to fly ash. In this study, fine powder bottom ash was mixed with various admixtures and a uniaxial compressive test was conducted on the mix to analyze the possibility of using it as a soil stabilization material. The bottom ash was pulverized for 30 hours to obtain a fine powder with a specific surface area of 6,870㎠/g, and a chemical component that could induce a pozzolan reaction between SiO₂ and Al₂O₃ was added to this powder. The uniaxial compressive test conducted on the mix of bottom ash and admixture gives the optimal blending ratio showing the optimal strength, and it was compared with the corresponding values for various ground improvement materials. As a result of the test, the strength of the soil stabilization material made from the fine powder of bottom ash at the beginning was higher or similar to that of a test group that was using actual soil stabilization materials, and the 28-day strength showed similar results. It is concluded in this work that the fine powder of bottom ash mixed with cement and sulfate-based waste gypsum can be used as a soil stabilization material.
여동준(Dong Jun YEO),최명수(Myung Soo CHOI),변정환(Jung Hwan BYUN),서정주(Jung Joo SUH),양정규(Jung Kyu YANG) 전남대학교 수산과학연구소 2006 수산과학연구소논문집 Vol.15 No.1
This paper deals with the free vibrations of folded plates by the transfer influence coefficient method. The governing equations of a non-circular cylindrical shell including a plate as special case are written in a coupled set of first order matrix differential equations. The Runge-Kutta-Gill integration method is used to solve the governing differential equations. The natural frequencies and corresponding mode shapes are calculated numerically for the folded plate of various crank angles. All boundary conditions and the intermediate supports between folded plate and foundation could be treated only by adequately varying the values of the spring constants.
여동준(Dong Jun YEO),최명수(Myung Soo CHOI),변정환(Jung Hwan BYUN),서정주(Jung Joo SUH),양정규(Jung Kyu YANG) 전남대학교 수산과학연구소 2006 수산과학연구소논문집 Vol.15 No.2
In this paper, the authors formulated analytical algorithm for the in-plane free vibration of a annular plate with intermediate support part by the transfer influence coefficient method (TICM) which is based on the successive transmission of influence coefficients on nodal circumferences. To confirm the effectiveness of the suggested algorithm, we analyzed the free vibration of a annular plate with three typical intermediate support parts by the TICM and the Transfer matrix method (TMM) on a personal computer. The computational result was that the TICM was superior to the TMM in the in-plane free vibration analysis of a annular plate with rigid intermediate supports.
변정환,여동준,Byeon, Jeong-Hwan,Yeo, Dong-Jun 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.2
In this study, a methodology of synchronous control has been developed that can is applied to position synchronization of a two-axes driving system such as overhead crane. The synchronous error is caused by model uncertainties and torque load at each axis. To overcome these problems, the synchronous control system has been composed of two disturbance observers to calculate the torque disturbance and one synchronous controller to eliminate synchronous error. By considering model uncertainties of each axis, the synchronous controller has been designed using H(sub)$\infty$ control theory. The effectiveness of the proposed method has been verified through simulation.