• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.649-663
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• 2002

We consider an unlimited fluid queueing model which has Fractional Brownian motion(FBM) as an input and a single server of constant service rate. By using the result of Duffield and O'Connell(6), we investigate the asymptotic tail-distribution of the stationary work-load. When there are multiple homogeneous FBM inputs, the workload distribution is similar to that of the queue with one FBM input; whereas for the heterogeneous sources the asymptotic work-load distributions is dominated by the source with the largest Hurst parameter.

• Communications for Statistical Applications and Methods
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• v.13 no.3
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• pp.651-656
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• 2006

Wu and Clements-Croome (2005) investigate the optimization problem of PM policies for situations where the quality of PM is a random variable with a certain probability distribution. However, they assume that the cost of preventive maintenance is constant, not depending on the quality of PM. Thus, this paper considers a periodic PM model when PM cost depends on the quality of PM activity. The optimal PM policy are presented for the extended PM model and the numerical examples are presented for illustrative purpose.

• Journal of Pharmaceutical Investigation
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• v.10 no.1
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• pp.1-3
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• 1980

The model of an isolated organ system has been developed to simulate the kinetic behavior of drug levels in an acting organ or site. The model is developed from basic considerations of drug distribution with hemodynamical and pharmacokinetical meanings. Model: It is considered a situation in which non-metabolic drug substance is injected into the arterial inflow of an isolated organ at constant rate. The volume of distribution and the concentration of drug in the venous outflow can be mathematically expressed as a function of time.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.5-14
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• 2017

A fan-motor assembly in a vacuum cleaner is analyzed through system-level analysis method. This system consisted of three components, a fan, motor, and the flow resistance of the motor, or of the vacuum cleaner. System-level analysis method is characterized by the combination of torque matching at a constant throttling condition between the fan and the motor and the pressure drop at a constant flow rate due to the flow resistance of the motor, or of the vacuum cleaner. The performance characteristics of the fan-motor assembly and the vacuum cleaner system could be predicted over the whole range of operation, based on the characteristics of each component. The predicted performance of the vacuum cleaner system through system-level analysis agreed well with the experimental results within 4.5% difference of pressure and 6% difference of the efficiency. The effect of flow resistance of a motor is investigated and it is found that the efficiency decrease of fan-motor assembly at the constant flow rate due to the flow resistance of a motor is determined by the flow resistance ratio(FRR), which is defined as a ratio of flow resistance of motor and the flow resistance of a constant throttling condition of a given point. The fan-motor assembly(S2 model) was modified to reduce the FRR from 9.0% to 2.4% and the experimental result shows that the efficiency of S2 model was improved by about 3% at best efficiency point.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.5-12
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• 2011

This study was focused on the reactivity of furnace slag against cadmium to design the vertical drain method with reactive column for improving contaminated sea shore sediment. The kinetic sorption test was performed by changing the initial concentration and pH. Using pseudo-second-order model, the reactivity of furnace slag was quantitatively analyzed. Equilibrium removal amount ($q_e$) of furnace slag increased and rate constant ($k_2$) decreased with the increase of initial cadmium concentration. With the increase of pH, the equilibrium removal amount ($q_e$) and rate constant ($k_2$) increased in the same initial concentration. Required retention time was related to the inverse of the product of the equilibrium removal amount ($q_e$) multiplied by rate constant ($k_2$). The required retention time could be used to design the length of reactive column.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.43-50
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• 2012

Two typical animal waste management practices, composting and stockpiling, were evaluated for their effect on the degradation of three veterinary antibiotics (VAs), chlortetracycline (CTC), tylosin (TYL), and monensin (MNS). The VAs were applied to horse manure plots subject to composting or stockpiling, and core samples were collected over a period of time. Selected buffer solutions were used to extract the VAs and analysis for concentration was conducted with solid phase extraction (SPE) followed by high performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) technique. The VAs demonstrated rapid dissipation within ten days followed by a gradual decrease in concentration until the end of the experimental period (141 days). All three VAs degraded more rapidly in the composting samples than in the stockpiling samples, particularly between 20 and 60 days of the observation period. Degradation of the three VAs generally followed a first-order kinetic model, and a fitted model with a calculated rate constant was determined for each treatment. TYL in composting showed the fastest degradation, with a calculated rate constant of $0.91day^{-1}$; the slowest degradation was exhibited by MNS in stockpiling, with rate constant of $0.17day^{-1}$. Calculated correlation coefficients ranged from 0.89 to 0.96, indicating a strong correlation between measured concentrations and fitted values in this study. Although concentration of TYL in composting treatment showed below detection limit during the test period, this study suggests that composting can reduce animal waste contaminants prior to field application as fertilizer.

• Microbiology and Biotechnology Letters
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• v.25 no.3
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• pp.235-239
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• 1997

Chlorococcum littorale has been grown in high $CO_2$ concentrations to utilize $CO_2$ gas in the polluted air. The effect of incident light intensity on the specific growth rate is expressed by a photoinhibition model, showing half- saturation constant, $K_0\;as\;8\;(W/m^2)$ and inhibition constant, Ki as 35 $(W/m^2)$. The maximum specific growth rate was also estimated as 0.095 (1/day) under this condition. This strain maintained the optimum growth rate in 20% of $CO_2$ gas but 50% of input $CO_2$ gas is the maximum concentration considering the economical efficiency. The maximum Specific $CO_2$ consumption rate, $qCO_2$ was measured as 17.48 (mg $CO_2/g$ dry wt./day) in batch cultivation, 11.2 (mg $CO_2/g$ dry wt./day) in fed-batch cultivation and 10.87 (mg $CO_2/g$ dry wt./day) at 0.065 (1/day) of dilution rate in continuous cultivation. The chemical composition of the biomass obtained from this process showed 32.5% of protein, 27.5% of lipid, 16.5% of carbohydrate and ash 11.7%.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.518-526
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• 2012

The objective of this research was to develop fugitive emission models of HFC-134a (Hydrofluorocarbon-134a) at the operation and disposal stages of passenger cars. It is essential to estimate the emission of HFC-134a from mobile air conditioner (MAC) due to its high Global Warming Potential (GWP) and extensive use as a refrigerant in MAC. The first-order emission model was introduced and the emission rate constant was assumed to be unvaried with time. A commercial recovery station of refrigerants was used to recover the HFC-134a from the MAC. Average emission rate constant and annual emission rate during the operation period of vehicle are estimated to be $0.0538{\pm}0.0092$ (n=21) $yr^{-1}$ and $5.2{\pm}0.6%$, respectively within a confidence interval of 95%. According to the model results, about 50% of HFC-134a would be emitted from the MAC during the 10 years operation of passenger cars. On the other hand, average remaining portion of HFC-134a in the MACs of scrap cars is $58.2{\pm}4.8%$ (n=50) within a confidence interval of 95%, suggesting that over 40% of the initially charged amount could be released fugitively after disposal provided that the HFC-134a would not be properly treated or recycled.

• Journal of Magnetics
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• v.7 no.4
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• pp.156-159
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• 2002

We have investigated the escape rate of nano-magnetic particle with a magnetic field applied along the easy axis. The model studied here is described by the Hamiltonian H=$K_1\hat{S}{_z^2}$ ＋ $K_2\hat{S}{_y^2}$ ＋ $g{\mu}_bB$ $\hat{S}_x(K_1>K_2>0)$ and the escape rate was calculated with in the semiclassical approximation. We have obtained a diagram for orders of the phase transition depending on the anisotropy constant and the external field. For $K_2$/$K_1>$0.85 the present model reveals the existence of the first order transition within the quantum regime.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.41-54
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• 1991

This paper aimed to analyse dose sensitivity to the controllable parameters of indoor radon $(^{222}Rn)$ and its decay products (Rn-D) by applying the input~output linear system theory. Physical behaviors of $^{222}Rn\;&\;Rn-D$ were analyzed in terms of $(^{222}Rn)$ gas -generation, -migation and -infiltration to indoor environments, and the performance output-function, i. e. mean dose equivalent to Tracho-Bronchial (TB) lung region, was assessed to the following extented ranges of the controllable paramenters; a) the ventilation rate $constant({\lambda}_v)\;:\;0{\sim}50[h^{-l}].\;b)$ the attachment rate $constant({\lambda}_a)\;:\;0{\sim}500[h^{-l}].\;c)$ the unattached-deposition rate constant (${\lambda}^u_d)\;:\;0-50[h-l]$. A linear input-output model was reconstructed from the original models in literatures, as follows, which was modified into the matrices consisting of 111 nodal equations; a) indoor $^{222}Rn\;&\;Rn-D$ Behaviour; Jacobi-Porstendoerfer-Bruno model.