• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.843-852
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• 2003

We present a brief account of the theory of diffusion-influenced kinetics of reactions involving polymers. The review will be based on the recent contributions from the authors. Both intrapolymer and interpolymer reactions are considered, and the effects of various physical factors, such as the chain length, chain stiffness, and hydrodynamic interactions, are described within a unified theoretical framework.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1659-1663
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• 2006

A many-body master equation is constructed by incorporating stochastic terms responsible for chemical reactions into the many-body Smoluchowski equation. Two forms of Langevin-type of memory equations describing the time evolution of dynamical variables under the influence of time-independent perturbation with an arbitrary intensity are derived. One form is convenient in obtaining the dynamics approaching the steady-state attained by the perturbation and the other in describing the fluctuation dynamics at the steady-state and consequently in obtaining the linear response of the system at the steady-state to time-dependent perturbation. In both cases, the kinetics of statistical averages of variables is found to be obtained by analyzing the dynamics of time-correlation functions of the variables.

• Journal of the Korean Chemical Society
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• v.52 no.3
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• pp.217-222
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• 2008

We investigate the kinetics of diffusion-influenced catalytic reactions occurring in small reaction volume. From a simple exact model study, we find that the reaction rate coefficient decreases with the size of reaction volume. The explicit expression for the average reaction rate constant is presented, which can be regarded as a generalization of well-known Collins-Kimball rate constant into the reactions occurring in a small reaction volume. It turns out that the traditional diffusion influenced reaction dynamics is followed by a single exponential relaxation phase with a rate constant dependent on the reaction volume for the catalytic reactions occurring in small reaction volumes.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.925-928
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• 2012

The accurate expression for the steady-state velocity of an irreversible enzyme-catalyzed reaction obtained by Shin and co-workers (J. Chem. Phys. 2001, 115, 1455) is generalized to allow for the rebinding of the product. The amplitude of the power-law ($t^{-1/2}$) relaxation of the free- and bound-enzyme concentrations to steady-state values is expressed in terms of the steady-state velocity and the intrinsic (chemical) rate constants. This result is conjectured to be exact, even though our expression for the steady-state velocity in terms of microscopic parameters is only approximate.

• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.398-404
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• 1992

We have investigated the kinetics of diffusion-influenced bimolecular reactions in which one reactant has an internal mode, called the gating mode, that activates or deactivates its reactivity intermittently. The rate law and an expression for the time-dependent rate coefficient have been obtained from the general formalism based on the hierarchy of kinetic equations involving reactant distribution functions. The analytic expression obtained for the steady-state reaction rate constant coincides with the one obtained by Szabo et al., who derived the expression by employing the conventional concentration-gradient approach. For the time-dependent reaction rate coefficient, we obtained for the first time an exact analytic expression in the Laplace domain which was then inverted numerically to give the time-domain results.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.202-206
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• 2009

Drying characteristics of fresh Korean-type rehmannia (jiwhang) noodle was investigated to determine drying kinetic parameters under the experimental conditions of 5 temperatures (30, 40, 60, 80, and $90^{\circ}C$). Drying curve of the noodle showed a biphasic pattern of decrease in drying rate with initial rapid drying followed by slow dehydration as the progress in drying. In all drying conditions, only falling drying rate period was observed and the drying rate of the noodle was greatly influenced by the drying temperature. The effective diffusion coefficients ($D_{eff}$) were determined by the diffusion model and their temperature dependency was determined using an Arrhenius equation. The activation energy ($E_a$) values for the drying of the noodle were 19.94 and 21.09 kJ/mol at the initial and the latter stage of dehydration, which were comparable to those of pasta or Japanese udong dehydration.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.456-459
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• 2005

Continuous cooling transformation behaviors were studied fur low carbon HSLA steels containing three different level $(1\~3\;wt\%)$ of Ni addition. Thermo-mechanical processing (TMP) simulations to construct continuous cooling (CCT) diagram were conducted by using Gleeble system. As cooling rate increased, pearlite, granular bainite, acicular ferrite, bainitic ferrite and lath martensite were transformed from deformed austenite. Fully bainitic microstructure were developed at all cooling rate condition in high Ni containing steel due to hardenability increasing effects of Ni. Ni also influenced the transformation kinetics. At the slowest cooling rate of $0.3^{\circ}C/s$, transformation delayed with decreasing Ni contents because of the diffusion of substitutional alloy elements. However, cooling rate slightly increased to $1^{\circ}C/s$, transformation kinetics accelerated with decreasing Ni contents because nucleation of bainite was sluggish due to hardening of residual austenite.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.197-202
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• 2006

In the reaction A + B $^\rightarrow_\leftarrow$ C, where A and B are ionic reactants having opposite charges, a B molecule approaching an A will experience a switching of the interaction potential when the A molecule is captured by one of the other B molecules in the medium. In the reversible case, the former B molecule still has a chance to react with the A, so that one needs to take into account the switched interaction between the reactant B and the product C as well as that between the reactants to treat the kinetics accurately. It is shown that this kind of interaction potential switching affects the relaxation kinetics in an intriguing way as observed in a recent experiment on an excited-state proton transfer reaction.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1986-1990
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• 2005

We study the relaxation kinetics of reversible reactions of the type A + B $^\leftarrow_\rightarrow$ C + B by applying the manyparticle kernel theory, which we have developed to investigate many particle effects on general diffusioninfluenced reactions. It is shown that for the target model, where A and C molecules are immobile and their interconversion is induced by the encounter with the B molecules that are present in much excess, the manyparticle kernel theory gives a result that coincides with the known exact result.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.720-723
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• 1996

The behavior of electrodeposition of amorphous nickel-phosphorus has been studied from the point of deposition mechanism, kinetic parameters, morphology and formation of alloy films. The electorode reaction and electrode kinetics of deposition of nickel were significantly influenced by the content of phosphorus. The cathodic deposition of nickel-phosphorus alloy might be governed by the diffusion process of phosphorous acid. The direction of growth layer of the nickel-phosphorus alloy was different with substrate material. The formation of nickel-phosphorus alloy films was affected considerably by the solution compositions, electrolytic conditions and properties of the material as an underlayer.