• Journal of Biosystems Engineering
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• v.15 no.1
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• pp.44-51
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• 1990

Four models in current use for cereal grain drying, equilibrium model, Morey model, partial differential equation model and simplified partial differential equation model, were modified to be suitable for natural air drying of barley. The predicted by the four models and experimental results were compared. Three models except equilibrium model predicted moisture comtent and grain temperature very well. But equilibrium model overpredicted moisture content and grain temperature of bottom layer. The degree of prediction of the four models for relative humidities of exhaust air didn't differ much from one another and equally the four models predicted relative humidity statisfatorily. Morey model took much shorter computing time than any other models. Therefore, considering the degree of prediction and computing time Morey model was the most suitable for natural air drying of barley.

• The Journal of the Korea Contents Association
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• v.9 no.10
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• pp.444-450
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• 2009

We have investigated biosorption kinetics and equilibrium of $Pb^2+$ and $Cr^2+$ using waste sludge, and separation efficiency of waste sludge by dissolved air flotation was evaluated in the various A/S ratio. The biosorption capacity and contact time were shown as a simulation of biosorption equilibrium and kinetics models. Biosorption equilibrium of the $Pb^2+$ and $Cr^2+$ onto the waste sludge could be fitted by the Langmuir, Freundlich, Redlich-Peterson, and Koble-Corrigan equation. The kinetics could be fitted by a pseudo-second-order rate equation more than a pseudo-first-order rate equation. The separation efficiency of waste sludge using DAF was kept above 90%.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.89-94
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• 2008

This paper deals with the method of self-equilibrium stress mode analysis of cable dome structures. From the point of view of analysis, cable dome structure is a kind of unstable truss structure which is stabilized by means of introduction of prestressing. The prestress must be introduced according to a specific proportion among different structural member and it is determined by an analysis called self-equilibrium stress mode analysis. The mathematical equation involved in the self-equilibrium stress mode analysis is a system of linear equations which can be solved numerically by adopting the concept of Moore-Penrose generalized inverse. The calculation of the generalized inverse is carried out by rank factorization method. This method involves a parameter called epsilon which plays a critical role in self-equilibrium stress mode analysis. It is thus of interest to investigate the range of epsilon which produces consistent solution during the analysis of self-equilibrium stress mode.

• Communications of the Korean Mathematical Society
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• v.15 no.1
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• pp.133-142
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• 2000

We consider some numerical solution methods for equilibrium equations Af + E$^{T}$ λ = r, Ef = s. Algebraic problems of this form evolve from many applications such as structural optimization, fluid flow, and circuits. An important approach, called the force method, to the solution to such problems involves dimension reduction nullspace computation for E. The purpose of this paper is to investigate the substructuring method for the solution step of the force method in the context of the incompressible fluid flow. We also suggests some iterative methods based upon substructuring scheme..

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.206-209
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• 1988

Fixed boundary MHD static equilibrium for the axisymmetric toroidal plasma is analyzed numerically. The Grad-Shafranov equation is solved using FFM. The toroidal current tenn is expressed by plasma pressure p($\psi$) and toroidal field function g($\psi$). The numerical results are compared to the Solovev analytic equilibrium for the verification of the analysis. For SNUT-79 tokamak device in Seoul National University, flux surfaces and toroidal current profiles according to the variation of p and g profiles are observed. Also the safety factor q and average beta are obtained.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.58-68
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• 1994

An equilibrium approach is suggested as an effective tool for the analysis of sheet metal forming processes on the basis of force balance together with geometric relations and plasticity theroy. In computing a force balance equation, it is required to define a geometric curve approximating the shape of the sheet metal at any step of deformation from the geometric interaction between the die and the deforming sheet. Then the geometic informations for contacting and non-contacting sections of the sheet metal such as the number and length of both non-contact region, contact angle, and die radius of contact section are known from the geometric forming curve and utilized for optimization by force balance equation. In computation, the sheet material is assumed to be of normal amisotropy and rigid-phastic workhardening. It has been shown that there are good agreements between the equilibrium approach and FEM computation for the benchmark test example and auto-body panels whose sections can be assumed in plane-strain state. The proposed equilibrium approach can thus be used as a robust computational method in estimating the forming defects and forming severity rather quickly in the die design stage.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.408-415
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• 2005

Existing results of some related experiments report that variation in the magnitude of prestressing force may leads to a change of dynamic properties of a PSC girder system. Since a usual dynamic equilibrium equation doesn't explain these phenomena, a modified dynamic equilibrium equation is derived in this paper by considering prestressing force as an internal energy of the system. The derived equation is applied to a modified beam element model is proposed. The proposed model validated by comparing the natural frequencies computed by the model with those from an existing experiment result.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.241-248
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• 2002

In this work, we calculated the vapor-liquid equilibrium of aqueous polymer solutions by using PRSV equation of state combined with $G^{ex}$ mixing rules(HVO, MHVL, MHV2, LCVM). From the comparison of calculated results with experimental data obtained from literature, we found that calculation results by using MHV1 mixing rule have showed small range of error than HVO, MHV2 and LCVM mixing rules. Calculation results by using the combination of MHV1 mixing rule and UNIFAC-FV model have showed the best result for selected aqueous polymer solutions.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.245-249
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• 2003

Vapor-liquid equilibrium data were obtained for system of propane + R227ea (Heptafluoropropane) over the temperature range from 253.15 K to 323.15 K at 10 K intervals. Experiments were performed in a circulation type apparatus by injecting vapor through liquid pool using a magnetic pump. This system forms azeotrope in the temperature range of this study. The experimental results were correlated with the Peng-Robinson (PR) equation of state and Redlich-Kwong-Soave (RKS) equation of state using the van der Walls one-fluid mixing rule and were compared with each other.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.329-337
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• 2001

This simulator is developed for the analysis of a MOSFET based on Thermally Coupled Energy Transport Model(TCETM). The simulator has the ability to calculate not only stationary characteristics but also non - stationary characteristics of a MOSFET. It solves basic semiconductor devices equations including Possion equation, current continuity equations for electrons and holes, energy balance equation for electrons and heat flow equation, using finite difference method. The conventional semiconductor device simulation technique, based on the Drift-Diffusion Model (DDM), neglects the thermal and other energy-related properties of a miniaturized device. I, therefore, developed a simulator based on the Thermally Coupled Energy Transport Model (TCETM) which treats not only steady-state but also transient phenomena of such a small-size MOSFET. In particular, the present paper investigates the breakdown characteristics in transient conditions. As a result, we found that the breakdown voltage has been largely underestimated by the DDM in transient conditions.