• 한국소음진동공학회논문집
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• 제15권2호
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• pp.169-175
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• 2005

In this paper, a novel vibration control scheme for a single-link flexible manipulator system without using a vibration feedback sensor is proposed. In order to achieve the vibration information of the flexible link, a reaction moment estimator based on the dynamic characteristics of the flexible manipulator is proposed. While the manipulator is maneuvering the reaction moment is reciprocally acting on the flexible link and the hub inertia due to the vibration of the link. A sliding mode controller based on the equivalent rigid body dynamics corresponding to the proposed flexible manipulator is then augmented with the reaction moment estimator to realize a decentralized control system. The reaction moment estimator is implemented via the first order low pass filter. The performance of the proposed control scheme is verified by computer simulation and experiment.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제17권4호
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• pp.221-237
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• 2013

In this paper an asymptotic numerical method named as Initial Value Method (IVM) is suggested to solve the singularly perturbed weakly coupled system of reaction-diffusion type second order ordinary differential equations with negative shift (delay) terms. In this method, the original problem of solving the second order system of equations is reduced to solving eight first order singularly perturbed differential equations without delay and one system of difference equations. These singularly perturbed problems are solved by the second order hybrid finite difference scheme. An error estimate for this method is derived by using supremum norm and it is of almost second order. Numerical results are provided to illustrate the theoretical results.

• Journal of applied mathematics & informatics
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• 제34권5_6호
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• pp.495-508
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• 2016

A singularly perturbed reaction-diffusion fourth-order ordinary differential equation(ODE) with discontinuous source term is considered. Due to the discontinuity, interior layers also exist. The considered problem is converted into a system of weakly coupled system of two second-order ODEs, one without parameter and another with parameter ε multiplying highest derivatives and suitable boundary conditions. In this paper a computational method for solving this system is presented. A zero-order asymptotic approximation expansion is applied in the second equation. Then, the resulting equation is solved by the numerical method which is constructed. This involves non-overlapping Schwarz method using Shishkin mesh. The computation shows quick convergence and results presented numerically support the theoretical results.

• Investigative Magnetic Resonance Imaging
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• 제22권1호
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• pp.26-36
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• 2018

Purpose: Children born with single ventricle physiology demonstrate poor growth rate and suffer from malnutrition, which lead to increased morbidity and mortality in this population. We assume that an anabolic steroid, oxandrolone, will promote growth in these infants by improving myocardial energy utilization. The purpose of this paper is to study the efficacy of oxandrolone on myocardial energy consumption in these infants. Materials and Methods: We modeled single ventricle physiology in a lamb by prenatally shunting the aorta to the pulmonary artery and then postnatally, we monitored cardiac energy utilization by quantitatively measuring the first order reaction rate constant, $k_f$ of the creatine-kinase reaction in the heart using magnetization transfer $^{31}P$ magnetic resonance spectroscopy, home built $^1H/^{31}P$ transmit/receive double tuned coil, and transmit/receive switch. We also performed cine MRI to study the structure and dynamic function of the myocardium and the left ventricular chamber. The spectroscopy data were processed using home-developed python software, while cine data were analyzed using Argus software. Results: We quantitatively measured both the first order reaction rate constant and ejection fraction in the control, shunted, and the oxandrolone-treated lambs. Both $k_f$ and ejection fraction were found to be more significantly reduced in the shunted lambs compared to the control lambs, and they are increased in oxandrolone-treated lambs. Conclusion: Some improvement was observed in both the first order reaction rate constant and ejection fraction for the lamb treated with oxandrolone in our preliminary study.

• Bulletin of the Korean Chemical Society
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• 제18권11호
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• pp.1199-1203
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• 1997

The investigation of cure kinetics of biphenyl epoxy (4,4-diglycidyloxy-3,3,5,5-tetramethyl biphenyl)-xylok resin system with four different catalysts was performed by differential scanning calorimeter using an isothermal approach. All kinetic parameters of the curing reaction including the reaction order, activation energy and rate constant were calculated and reported. The results indicate that the curing reaction of the formulations using triphenylphosphine (TPP) and 1-benzyl-2-methylimidazole (1B2MI) as a catalyst proceeds through a first order kinetic mechanism, whereas that of the formulations using diazabicyloundecene (DBU) and tetraphenyl phosphonium tetraphenyl borate (TPP-TPB) proceeds by an autocatalytic kinetic mechanism. To describe the cure reaction in the latter stage, we have used the semiempirical relationship proposed by Chern and Poehlein. By combining an nth order kinetic model or an autocatalytic model with a diffusion factor, it is possible to predict the cure kinetics of each catalytic system over the whole range of conversion.

• Bulletin of the Korean Chemical Society
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• 제2권4호
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• pp.138-141
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• 1981

The rate of the bromine-exchange reaction between gallium bromide and i-butyl bromide in 1,2,4-trichlorobenzene or nitrobenzene was measured at 19, 25 and $40^{\circ}C$, using i-butyl bromide labelled with Br-82. The results indicated that the exchange reaction was second order with respect to gallium bromide and first order with respect to i-butyl bromide. The third-order rate constant determined at $19{\circ}C$ was $3.28{\times}10^{-2}l^2{\cdot}mole^{-2}{\cdot}sec^{-1}$ in 1,2,4-trichlorobenzene and $9.25{\times}10^{-3}l^2{\cdot}mole^{-2}{\cdot}sec^{-1}$ in nitrobenzene. The activation energy, the enthalpy of activation and the entropy of activation for the exchange reaction were also determined.

• 한국물환경학회지
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• 제38권5호
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• pp.211-219
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• 2022

In this study, the effect of liquid height/volume on sonochemical oxidation reactions was investigated in 300 kHz sonoreactors. The gas mixture of Ar/O₂ (50:50) was applied in two modes including saturation and sparging, and zero-order reaction (KI dosimetry) and first-order reaction (Bisphenol A (BPA) degradation) were used to quantitatively analyze sonochemical oxidation reactions. For the zero-order reaction, the highest sonochemical oxidation activity was obtained for the liquid height of 5𝛌, and the lowest height for both the gas saturation and sparging conditions. In addition, the sparging did not enhance the sonochemical oxidation activity for all height conditions except for 50𝛌, where very low activity was obtained. It was found that in sonochemiluminescence (SCL) images the sonochemical active zone was formed adjacent to the liquid surface for the gas sparging condition due to the formation of the standing wave field while the active zone was formed adjacent to the transducer at the bottom due to the blockage of ultrasound. For the first-order reaction, the highest activity was also obtained at 5𝛌 and the comparison based on the reactant mass was not appropriate because the concentration of the reactant (BPA) decreased significantly as the reaction time elapsed. Consequently, it was revealed that the determination of optimal liquid height (ultrasound irradiation distance) based on the wavelength of the applied ultrasound frequency was very important for the optimal design of sonoreactors in terms of reaction efficiency and reactor size.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제2권1호
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• pp.79-84
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• 1998

The rates of absorption of carbon dioxide into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) were measured using a semibatch stirred vessel with a plane gas-liquid interface at $25^{\circ}C.$ The absorption rates under the fast reaction regime were analysed using chemical absorption theory. The reaction was found to be first order with respect to both $CO_2$ and the amine.

• 한국환경과학회지
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• 제2권1호
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• pp.79-84
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• 1993

The rates of absorption of carbon dioxide into aqueous solutions of 2-amino-2-methyl-1 propanol (AMP) were measured using a semibatch stirred vessel with a plane gas-liquid interface at $25^{\circ}C$. The absorption rates under the fast reaction regime were analysed using chemical absorption theory. The reaction was found to be first order with respect to both $CO_2$ and the amine.

• Bulletin of the Korean Chemical Society
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• 제9권5호
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• pp.298-303
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• 1988

Kinetic studies on cupric ion ($Cu^{2+}$) oxidation of 1-benzyl- and 1-aryl-1,4-dihydronicotinamides (XNAH) in aqueous solution were performed. In the presence of dioxygen ($O_2$), the reaction followed first order kinetics with respect to both XNAH and $Cu^{2+}$. The oxidation reaction was found to be independent and parallel to the acid-catalyzed hydration reaction of XNAH. The catalytic role of $Cu^{2+}$ for the oxidation of XNAH in the presence of $O_2$ was attributed to $Cu^{2+}/Cu^+$ redox cycle by the reactions with XNAH and $O_2$. The second order rate constants of the Cu2+ oxidation reaction kCu, and acid-catalyzed hydration reaction $k_H$ were strongly dependent on the nature of the substituents in 1-aryl moiety. The slopes of log $k_{Cu}$ vs log $K_H$ and log $k_{Cu}$ vs ${\sigma}_p$ of the substituents plots were 1.64 and -2.2, respectively. This revealed the greater sensitivity of the oxidation reaction rate to the electron density on the ring nitrogen than the hydration reaction rate. A concerted two-electron transfer route involving XNAH-$Cu^{2+}$ complex was proposed for mechanism of the oxidation reaction.