• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.296-305
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• 2006

The adsorption and persistence of pencycuron {1-(4-chlorobenzyl) cyclopentyl-3-phenylurea} in soils were investigated under laboratory and field conditions to in order to assess the safety use and environmental impact. In the adsorption rate experiments, a significant power function of relation was found between the adsorbed amount of pencycuron and the shaking time. Within one hour following the shaking, the adsorption amounts in the SCL and the SiCL were 60 and 65% of the maximum adsorption amounts, respectively. The adsorption reached a quasi-equilibrium 12 hours after shaking. The adsorption isotherms followed the Freundlich equation. The coefficient (1/n) indicating adsorption strength and degree of nonlinearity was 1.45 for SCL and 1.68 to SiCL. The adsorption coefficients ($K_d$) were 2.31 for SCL and 2.92 to SiCL, and the organic carbon partition coefficient, $K_{oc}$, was 292.9 in SCL and 200.5 inSiCL. In the laboratory study, the degradation rate of pencycuron in soils followed a first-order kinetic model. The degradation rate was greatly affected by soil temperature. As soil incubation temperature was increased from 12 to $28^{\circ}C$, the residual half life was decreased from 95 to 20 days. Arrhenius activation energy was 57.8 kJ $mol^{-1}$. Furthermore, the soil moisture content affected the degradation rate. The half life in soil with 30 to 70% of field moisture capacity was ranged from 21 to 38 days. The moisture dependence coefficient, B value in the empirical equation was 0.65. In field experiments, the half-life were 26 and 23 days, respectively. The duration for period of 90% degradation was 57 days. The difference between SCL and SiCL soils varied to pencycuron degradation rates were very limited, particularly under the field conditions, even though the characteristics of both soils are varied.

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.209-220
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• 2004

Adsorption behavior of Cu onto Hwangto, from Pankok-ri, Kosung-gun, suspension was studied using Cu batch adsorftion experiment and computer program MINTEQA2 and FITEQL 3.2. The sorption of copper was investigated as a function of pH, copper concentration and $NaNO_3$ background concentration (0.01 and 0.1 M). The concentration of copper was analyzed using ICP-AES. The sorption of copper onto Hwangto suspension increased with increasing pH and copper concentration. The adsorption percentage of copper drastically increased from pH 5.5 to 6.5, and reached nearly 100% at pH 7.5. Because the amount of copper solution and the ionic strength of background electrolyte may not affect the sorption of copper onto Hwangto, the copper ion may be combined at the surface of Hwangto as an inner-sphere complex. Using the MINTEQA2 program, the speciation of copper was calculated as a function of pH and copper concentration. The concentration of $Cu^{2+}$ decreased and that of $Cu(OH)_2$ increased with increasing pH. The uptake of copper in the Hwangto suspension was simulated by FITEQL3.2 program using two sites-three pKas model, which is composed of silicate reaction site and Fe oxide reaction site. The copper absorption reaction constants were calculated in the case of 2～6 mL of copper solution. The Fe oxide reaction site rapidly adsorbs copper ion between pH 4.5～6.5. Silicate reaction site adsorbs little copper ion at low copper concentration but much at high copper concentration. The removal amount of copper by precipitation was negligible in comparison with that of adsorption. The Fe oxide reaction site may has higher adsorption affinity of copper ion than silicate reaction site.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.46.3-46
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• 2002

Most of the process control algorithms in practice are based on the finite dimensional control theory. However, many chemical processes are described by partial differential equations (PDE's) and are infinite dimensional in nature due to spatial variation. Especially when the convection is dominant and thus diffusion can be ignored, chemical processes that are described by a system of first order hyperbolic PDE's. Such processes include tubular reactors, fixed bed reactors and pressure swinging adsorption. Conventionally such infinite dimensional systems described by PDE's are controlled by finite dimensional controllers that are designed through finite dimensional reduction of the process m...

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.49.2-49.2
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• 2010

Copper oxide films have been deposited on silicon substrates by direct current magnetron sputtering of Cu in O2 / Ar gas mixtures. The target oxidation occurring as a result of either adsorption or ion-plating of reactive gases to the target has a direct effect on the discharge current and the resulting composition of the deposited films. The kinetic model which relates the target oxidation to the discharge current was proposed, showing the one-to-one relationship between discharge current characteristics and film stoichiometry of the deposited films.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.157-160
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• 1992

표면에 여러 가지 기능성기를 가지는 microspheres는 immunoassay, drug delivery system, cell separation등 의용공학분야에 응용이 기대되고 있다. 이들 분야의 응용을 위하여 유화제를 사용하지 않으면서, 기존의 회분식, 반회분식, seed 중합법등의 문제점을 극복한 two stage shot growth technique올 개발하여 여러 가지 기능성기가 표면에 도입된 microspheres를 제조하였으며, 응용의 전단계로서 이들 microspheres에 대한 모델 단백질(BSA)의 흡착실험을 pH, 기능 성기의 종류와 양, BSA농도를 변수로 행하여 최대 흡착량을 보이는 조건을 결정하였다.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.72-78
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• 1996

The breakthrough curves of a sampling tube were studied to predict the service life of a respirator cartridge for organic vapors. The fixed bed adsorption model was applied to respirator cartridge and it's variables were calculated from tile experiment of sampling tube. By the experiment and simulation, it was possible to predict the service life of a respirator cartridge, however, not adequate at low $CCl_4$ concentration less than 700ppm and at high air humidify. The breakthrough curves of sampling tube were irregular compare to that of respirator cartridge due to .packing density.

• Microbiology and Biotechnology Letters
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• v.23 no.4
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• pp.425-431
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• 1995

A kinetic model of the cyclodextrin formation in a heterogeneous enzyme reaction system using swollen extrusion starch as substrate was derived emphasing the structural features of extrusion starch. The degree of gelatinization, the ratio of accessible and inaccessible portion of extrusion starch, adsorption of CGTase on swollen starch, the structural transformation during reaction, and product inhibition caused by produced CDs were considered in deriving kinetic model. Various kinetic constants were also evaluated. The derived kinetic equation was numerically simulated, which result showed that the derived kinetic equations can be used to predict the experimental data reasonably well under the various experimental conditions. Kinetic model can be utilized for the optimization of enzyme reactor and the process development for CD production from swollen extrusion starch.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.1
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• pp.105-112
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• 1999

Model predicting the respiration rate of pear under modified LDPE film pouch has been developed. The assumptions of the model have three bases; 1) respiration rate is depending on $CO_2$ and $O_2$ concentration in the package, 2) the oxidation of glucose in pear generates carbon dioxides, and 3) gases permeation through the package film bases on the Langmuir adsorption theory and Fick's law. The simulated results agreed fairly well with the experimental data so as this model to be useful in designing the modified atmospheric packaging system.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.49-54
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• 2006

The present study conducted a numerical modeling on the diesel SCR (selective catalytic reduction) system using ammonia as a reductant over vanadium-based catalysts $(V_2O_5-WO_3/TiO_2)$. Transient modeling for ammonia adsorption/desorption on the catalyst surface was firstly carried out, and then the SCR reaction was modeled considering for it. In the current catalytic reaction model, we extended the pure chemical kinetic model based on laboratory-scale powdered-phase catalyst experiments to the chemico-physical one applicable to realistic commercial SCR reactors. To simulate multi-dimensional heat and mass transfer phenomena, the SCR reactor was modeled in two dimensional, axisymmetric domain using porous medium approach. Also, since diesel engines operate in transient mode, the present study employed an unsteady model. In addition, throughout simulations using the developed code, effects of space velocity on the DeNOx performance were investigated.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.43-44
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• 1995

The diffusion behavior of liquid into polymer has been described by Fick's law, but the departure from Fickian diffusion is frequently found. In this study, 'noble' expressions for the rates of relaxation and sorption are introduced to eliminate these limitations. The ralaxation-sorption coupled mechanism model are based on the possibility of contacting liquid molecule and the active site which has the numerical concept of free volume. The concept has an analogy of reaction rate expressed by the possibility of collision with molecules and used in adsorption and reactive extraction etc. The new model simulated by Rungc-Kutta method for initial-value problem and Fickian diffusion is caompared with experimental data. The results show that the ralaxation-sorption coupled mechanism is able to account well for Fickian and non-Fickian sorption behavior including sigmoid and two-stage. In addition, this model has a chance of expansion to multi-component sorption with ease.