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DSMC-IP 방법을 이용한 삼차원 희박기체 유동 해석
최영재(Y.J. Choi),권오준(O.J. Kwon) 한국전산유체공학회 2019 한국전산유체공학회지 Vol.24 No.1
In the present study, the information preservation(IP) method was employed to the three dimensional direct simulation Monte-Carlo(DSMC) solver to simulate the low-speed rarefied gas flows efficiently. It was known that the IP method can reduce the statistical scatter problems of the DSMC method. Firstly, the verification of the DSMC solver was conducted to compare with the results of the DSMC-IP solver. After that, two cases of flow problems were simulated by the developed DSMC-IP solver. One is the thermal diffusion flows, and the other is the low-speed flows around the sphere. To find the effects of the IP method, the both cases were calculated by the pure DSMC method using same number of sampling of particles. Through the results of the thermal diffusion flows, it was found that the temperature scatters were reduced in the results of the DSMC-IP solver by comparing with the results of the pure DSMC solver. It was also shown that the velocity scatters decreased in the results of the IP method from the sphere problems. In addition, it was observed that the IP method gets the reasonable results using a relatively less number of sampling of particles than the pure DSMC method. As a result, it was obtained that the developed DSMC-IP solver is a more efficient method for the low-speed rarefied gas flows than the pure DSMC solver.
최영재(Y. J. Choi),신정훈(J. H. Shin),홍원표(W. P. Hong),이석우(S. W. Lee),최헌종(H. Z. Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Dynamically changing customer demands request manufacturers to make quality products with cheaper prices and shorter delivery. To survive in the global market, the manufacturing industry of today needs to be equipped with advanced technologies including IT as well as substantial infrastructure. Under this situation, we found that collaboration is the right answer for manufacturers to survive by strengthening relations between companies instead of competing against each other. For facilitating collaboration among Korean SMEs, we performed i-Manufacturing project from 2005. Through this project, we applied IT into the conventional manufacturing industry by developing business models and collaboration systems. In this paper, we introduce collaborative production management model and system including shop floor control.
Direct observation of magnetodielectric effect in type-I multiferroic PbFe0.5Ti0.25W0.25O3
J.Y. Moon,M.K. Kim,H.Y. Choi,S.H. Oh,Y. Jo,이나라,최영재 한국물리학회 2015 Current Applied Physics Vol.15 No.11
In type-I multiferroics, where ferroelectricity and magnetism arise from different origins, the explicit measurement of magnetoelectric effect is commonly prohibited due to the weak magnetoelectric coupling. From our investigation of magnetic and dielectric properties in a perovskite PbFe0.5- Ti0.25W0.25O3, we have directly demonstrated magnetic-field-driven change of dielectric constant in a highly non-linear fashion. Our result offers a potential utilization of magnetoelectric functionality in type-I multiferroics.