• Journal of computational fluids engineering
• /
• v.19 no.2
• /
• pp.58-65
• /
• 2014

The adaptive wavelet method is studied for the enhancement of computational efficiency of three-dimensional flows. For implementation of the method for three-dimensional Euler equation, wavelet decomposition process is introduced based on the previous two-dimensional adaptive wavelet method. The order of numerical accuracy of an original solver is preserved by applying modified thresholding value. In order to assess the efficiency of the proposed algorithm, the method is applied to the computation of flow field around ONERA-M6 wing in transonic regime with 4th and 6th order interpolating polynomial respectively. Through the application, it is confirmed that the three-dimensional adaptive wavelet method can reduce the computational time while conserving the numerical accuracy of an original solver.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.10a
• /
• pp.579-582
• /
• 2008

Three dimensional(3D) Poisson's equation is used to calculate the potential variation in the channel to analyze subthreshold current and short channel effect(SCE). The analytical model has been presented to lessen calculating time and understand the relationship of parameters. The accuracy of this model has been verified by the data from 3D numerical device simulator and variation for dimension and process parameters has been explained. The model has been developed to obtain channel potential of FinFET according to channel doping and to calculate subthreshold current and threshold voltage.

• Journal of Korean Society of Forest Science
• /
• v.96 no.1
• /
• pp.40-47
• /
• 2007

The objectives of this study were to derive site index and stem volume prediction equation based on stem analysis data for Larix leptolepis in Jinan region. The function for site index was developed by algebraic difference equation method. Polymorphic site index family curves with base age of 40 were presented based on the Schumacher height equation. The best stem volume prediction equation was suggested as $V=0.00260+0.00000399D^2H$. The simultaneous F-test using this equation showed that the estimated tree stem volumes were not significantly different (${\alpha}=0.05$ level) from the observed stem volumes for model evaluation. Therefore, site index and volume prediction equations prepared in this study could provide an indication of site quality and basic information for making of yield table, and could be used for rational forest management of Larix leptolepis stands grown in Jinan region.

• Korean Journal of Food Science and Technology
• /
• v.18 no.2
• /
• pp.77-81
• /
• 1986

The water sorption isotherms of individual insoluble components of corn starch, isolated soybean protein (ISP) and casein and their binary mixtures of corn starch-lSP and corn starch-casein were measured and analyzed. BET monolayer values and Smith plot parameters from the results of sorption isotherms were calculated by mass balance concept . The comparisons between experimental and predicted values resulted in an error of 2.29% for equilibrium moisture content and an error of 2.95% in monolayer value for the mixture 50% corn starch-50% ISP. On the other hand , for the mixture 50% corn starch-50% casein the errors were 2.66% and-5.34%, respectively.

• Nuclear Engineering and Technology
• /
• v.16 no.2
• /
• pp.89-96
• /
• 1984

A toroidal-field (TF) coil with a pure tension D-shape curve is designed for the confinement of high-temperature plasmas in the SNUT-79, which is a tokamak being built at Seoul National University. A toroidal assembly of 16 D-shape TF coils is designed to produce the magnetic field of up to 3T, of which ripples appear to be below 4% of the average toroidal field in the plasma region. Exact positions and currents in six equilibrium coils distributed symmetrically in the z=0 plane are found by the solution of a set of linear equations which is transformed from a Fredholm integral equation of the first kind. The decay indices resulted from equilibrium field indicate that the stability condition for vertical and horizontal displacements is satisfied.

• Journal of Energy Engineering
• /
• v.17 no.1
• /
• pp.23-30
• /
• 2008

The neutron kinetic analysis methods for the molten-salt reactors are quite different from those for conventional solid-fuel reactors, which do not take into account the flowing-fuel-induced neutronics effects. Therefore, for dynamics and safety analyses of the molten-salt reactor systems, the conventional kinetics codes would not be appropriate to accurately predict its transient behaviors. A point-kinetics with flowing- fuel model has been used to assess the fluid-fuel reactor system safety, but recognized as not to be sufficient to simulate spatial distributions of delayed-neutron precursors and neutron populations during transients for given detail reactor models. In order to meet this requirement, AMBIKIND, a 2-group, 2-dimensional neutron kinetics code suitable for the molten-salt reactor systems was developed. This paper explains the code's theoretical and numerical descriptions and, as a part of its verification, includes some simulation results of MSRE stability experiments. Even though the present reactor model does not include the recirculation effect of the fuel-salt through the reactor system, the AMBIKIN2D code should be able to predict the power and phase shift at various power levels and reactivity insertions with better accuracy.

• Proceedings of the KIPE Conference
• /
• 2013.11a
• /
• pp.41-43
• /
• 2013

PMSM 구동을 하였을 때, 인버터의 지령전압과 출력전압 사이에 왜곡이 발생하며, 대부분 Dead Time에 의한 영향 이다. 전압왜곡을 보상하는 여러 가지 방법 들이 연구되어왔다. 하지만 전압 왜곡의 보상이 abc 축 또는 dq축에서 이루어지고 있으나 어느 방식이 더 좋은지에 대한 검토가 없었다. 본 논문에서는 d-q축 전압방정식과 abc축 전압방정식으로부터 왜곡된 전압을 보상하는 방법을 비교한다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.1
• /
• pp.70-77
• /
• 1986

Turbulent mixing field with recirculating flow which is formed by injecting gaseous fuel on the main air stream is solved numerically by a finite difference method. The turbulence model for obtaining transport properties was k-.epsilon. model, which was obtained from turbulent kinetic energy and its dissipation rate. Considering the effects of streamline curvature, modified k-.epsilon model was used. Generally, Modified k-.epsilon. model makes better predictions than standard model, and from this result, it is recognized that standard model has deficiency when applied to turbulent recirculating flows, and that modified k-.epsilon. model takes into account of streamline curvature effects properly. Meanwhile, A more study will be necessary to find the reason why large differences between predicted and experimental turbulent kinetic energy exist.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.10a
• /
• pp.215-216
• /
• 2009

By growing the capacity of container in the world, main container terminal in countries introduces the automated container equipments and try to improve the productivity for handling the container. ARMC(Automated Rail Mounted Crane) is installed in automated container terminal and expected the high efficiency of productivity by using minimum-time control method. However recently by the GREEN Port policy, high energy efficiency method for container equipments is importance issue in ports. In this paper, the 3-dimensional modelling of AMRC is discussed and the acceleration characteristics for ARMC is analyzed By using the results of this paper, the advanced controller for the crane will be developed in future.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.1
• /
• pp.92-96
• /
• 1996

To elucidate the flow properties of carboxymethyl chitin (CM-chitin), the critical concentration and flow equation of aqueous CM-chitin solution were investigated. The concentration of $0.8\%$ appeared to be the critical concentration. So interaction occurred between polymer chains in the CM-chitin solutions had the higher concentration than $0.8\%$ but not in lower than $0.8\%.\;0.5\%$ CM-chitin solution was revealed as a newtonian flow but $1.0\%$ CM-chitin solution showed a pseudoplastic flow. Flow constants of $3.0\%$ CH-chitin solution were 0.0908cp for $\eta_\infty$, 770cp for $\eta_0$, 0.81 for $\beta$ and 0.36 for n. Therefore, flow equation of $3.0\%$ CM-chitin solution was as follow; $$\eta=0.1+\{{770/(1+0.81D^{0.36})\}$$.