• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.368-376
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• 2009

Studies on the effect of the wall-ion, wall-water, water-ion and ion-ion interaction on properties of water and ions in nano-channels have been performed through the use of different kinds of ions or different models of potential energy between wall-ion or wall-water. On this paper, we address the effect of water-wall interaction potential on the properties of confined aqueous solution by using the molecular dynamics (MD) simulations. As the interaction potential energies between water and wall we employed the models of the Weeks-Chandler-Andersen (WCA) and Lennard-Jones (LJ). On the MD simulations, 680 water molecules and 20 ions are included between uniformly charged plates that are separated by 2.6 nm. The water molecules are modeled by using the rigid SPC/E model (simple point charge/Extended) and the ions by the charged Lennard-Jones particle model. We compared the results obtained by using WCA potential with those by LJ potential. We also compared the results (e.g. ion density and electro-static potential distributions) in each of the above cases with those provided by solving the Poisson-Boltzmann equation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.15-21
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• 1991

Jones [11], [12]developed a measurement method of the economic depreciation by infinite-horizen linear program model. This paper models an economic depreciation schedule in constant price based on the infinite-horizen LP. And the appropriate application of the maintenance/operating cost, the discount rate, the taxation and the price fluctuation in the model was suggested.

• Bulletin of the Korean Chemical Society
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• v.2 no.1
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• pp.17-24
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• 1981

Thermodynamic properties such as sublimation pressures, enthalpies and entropies of sublimation, enthalpies and entropies of solid krypton and xenon are calculated from $0{\circ}K$ to the triple point, using the vacancies-in-solid model. The Mie-Lennard-Jones 12,6 potential in uniform potential field is used. The results are compared with the calorimetric and sublimation pressure values, and are in a good agreement with the available calorimetric and sublimation pressure values.

• Advances in Computational Design
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• v.5 no.4
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• pp.417-443
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• 2020

Tunnels have been an integral part of human civilization. Due to complexity in its design and structure, the stability of underground structures under extreme loading conditions has utmost importance. Increased terrorism and geo-political conflicts have forced the engineers and researchers to study the response of underground structures, especially tunnels under blast loading. The present study has been carried out to seek the response of tunnel structures under blast load using the finite element technique. The tunnel has been considered in quartzite rock of northern India. The Mohr-Coulomb constitutive model has been adopted for the elastoplastic behaviour of rock. The rock model surrounding the tunnel has dimensions of 30 m x 30 m x 35 m. Both unlined and lined (concrete) tunnel has been studied. Concrete Damage Plasticity model has been considered for the concrete lining. Four different parameters (i.e., tunnel diameter, liners thickness, overburden depth and mass of explosive) have been varied to observe the behaviour under different condition. To carry out blast analysis, Coupled-Eulerian-Lagrangian (CEL) modelling has been adopted for modelling of TNT (Trinitrotoluene) and enclosed air. JWL (Jones-Wilkins-Lee) model has been considered for TNT explosive modelling. The paper concludes that deformations in lined tunnels follow a logarithmic pattern while in unlined tunnels an exponential pattern has been observed. The stability of the tunnel has increased with an increase in overburden depth in both lined and unlined tunnels. Furthermore, the tunnel lining thickness also has a significant effect on the stability of the tunnel, but in smaller diameter tunnel, the increase in tunnel lining thickness has not much significance. The deformations in the rock tunnel have been decreased with an increase in the diameter of the tunnel.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.5-10
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• 2010

Among a variety of cleaning processes, the cryogenic carbon dioxide ($CO_2$) cleaning has merits because it is highly efficient in removing very fine particles, innoxious to humans and does not produce residuals after the cleaning, which enables us to extend its area of coverage in the semi-conductor fabrication society. However, the cryogenic carbon dioxide cleaning method has some technical research issues in aspect to particles' adhesion and removal. To resolve these issues, performing an analysis for the identification of particle adhesion mechanism is needed. In this study, a research was performed by a theoretical approach. To this end, we extended the G-T (Greenwood-Tripp) model by applying the JKR (Johnson-Kendall-Roberts) and Lennard-Jones potential theories and the statistical characteristics of rough surface to investigate and identify the contact, adhesion and deformation mechanisms of soft or hard particles on the rough substrate. The statistical characteristics of the rough surface were taken into account through the employment of the normal probability distribution function of the asperity peaks on the substrate surface. The effects of surface roughness on the pull-off force for these particles were examined and discussed.

• Journal of the Korean Data and Information Science Society
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• v.20 no.1
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• pp.1-9
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• 2009

Let us consider that the variance function in regression model has a discontinuity/change point at unknown location. Yu and Jones (2004) proposed the local polynomial fit to estimate the log-variance function which break the positivity of the variance. Using the local polynomial fit, Huh (2008) estimate the discontinuity point of the log-variance function. We propose a test for the existence of a discontinuity point in the log-variance function with the estimated jump size in Huh (2008). The proposed method is based on the asymptotic distribution of the estimated jump size. Numerical works demonstrate the performance of the method.

• Korea-Australia Rheology Journal
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• v.18 no.3
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• pp.161-167
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• 2006

This study presents results on the numerical simulation of Newtonian and non-Newtonian flow in a channel obstructed by an asymmetric array of obstacles for clarifying the descriptive ability of current non-Newtonian constitutive equations. Jones and Walters (1989) have performed the corresponding experiment that clearly demonstrates the characteristic difference among the flow patterns of the various liquids. In order to appropriately account for flow properties, the Navier-Stokes, the Carreau viscous and the Leonov equations are employed for Newtonian, shear thinning and extension hardening liquids, respectively. Making use of the tensor-logarithmic formulation of the Leonov model in the computational scheme, we have obtained stable solutions up to relatively high Deborah numbers. The peculiar characteristics of the non-Newtonian liquids such as shear thinning and extension hardening seem to be properly illustrated by the flow modeling. In our opinion, the results show the possibility of current constitutive modeling to appropriately describe non-Newtonian flow phenomena at least qualitatively, even though the model parameters specified for the current computation do not precisely represent material characteristics.

• Journal of the korean society of oceanography
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• v.39 no.4
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• pp.222-233
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• 2004

Using nitrogen as the limiting nutrient, the default version of a microplankton-detritus model linked chlorophyll concentration to the autotroph nitrogen. However, phosphorus dynamics were added to simulate the results of a microcosm experiment. Using standard parameter values with a single value of microheterotroph fraction in the microplankton taken from the observed range, the best simulation successfully captured the main features of the time-courses of chlorophyll and particulate organic carbon, nitrogen and phosphorus, with root-mean-square error equivalent to 29% of particulate concentration. A standard version of microbiological model assumes complete internal cycling of nutrient elements; adding a term for ammonium and phosphate excretion by microheterotrophs did not significantly improve predictions. Relaxing the requirement for constant microheterotroph fraction resulted in an autotroph-heterotroph model AH, with dynamics resembling those of a Lotka-Volterra predator-prey system. AH fitted the microcosm data worse than did MP, justifying the suppression of Lotka-Volterra dynamics in MP. The paper concludes with a discussion of possible reasons for the success of the simple bulk dynamics of MP in simulating microplankton behaviour.

• The Journal of Information Technology
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• v.1 no.2
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• pp.209-227
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• 1998

This study examines the relation between accruals components of earnings and stock return. Earnings are decomposed into four components: discretionary accruals, nondiscretionary accruals, nondiscretionary income and cash flow from operations. Because reported earnings in financial statement consist of cash flow from operations plus total accruals. We decompose total accruals into a discretionary accruals and a nondiscretionary accruals separately, This paper examines the incremental informational content of discretionary accruals and nondiscretionary accruals components of net income by regressing return on earnings'components in multivariate models. The empirical analysis is conducted on a sample of 1,580 firm-years comprising 158 firms during 1984-1995. Discretionary accruals are obtained by decomposing total accruals into discretionary and nondiscretionary accruals components, using a pooled variation of the Jones model(1991). These findings suggest that the discretionary accruals(measured using a variation the Jones model) is priced by the stock market. Specifically, the discretionary accruals and cash flow from operations are positively associated with the stock return, and also nondiscretionary income, discretionary accruals are positively associated with the stock return. While this result is consistent with the market prices the discretionary accruals because it captures value-relevant information. Additional test report evidence consistent with nondiscretionary accruals conveying information about the stock return.

• The Journal of Information Technology
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• v.7 no.3
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• pp.19-36
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• 2004

This study examines the relation between accruals components of earnings and stock return. Earnings are decomposed into four components: discretionary accruals, nondiscretionary accruals, nondiscretionary income and cash flow from operations. Because reported earnings in financial statement consist of cash flow from operations plus total accruals. We decompose total accruals into a discretionary accruals and a nondiscretionary accruals separately. This paper examines the incremental informational content of discretionary accruals and nondiscretionary accruals components of net income by regressing return on earnings' components in multivariate models. The empirical analysis is conducted on a sample of 1,580 firm-years comprising 158 firms during 1991-2003. discretionary accruals are obtained by decomposing total accruals into discretionary and nondiscretionary accruals conponents, using a pooled variation of the Jones model(1991). These findings suggest that the discretionary accruals(measured using a variation the Jones model) is priced by the stock market. Specifically, the discretionary accruals and cash flow from operations are positively associated with the stock return, and also nondiscretionary income, discretionary accruals are positively associated with the stock return. While this result is consistent with the market prices the discretionary accruals because it captures value-relevant information. Additional test report evidence consistent with nondiscretionary accruals conveying information about the stock return.