• Particle and aerosol research
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• v.11 no.3
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• pp.77-85
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• 2015

A Belousov-Zhabotinsky reaction in a liquid-liquid system under microwave radiation was observed under non-stirring conditions. To control this non-equilibrium reaction, nano-particle, which is active under microwave irradiation, was added to the solution. Color changes of the solution during the oscillatory reaction were found to be influenced by the irradiation power although the droplet temperature was equal to the temperature of surrounding oil. During the irradiation, the period of oscillation became shorter because the reaction rate was faster. It could also be observed that there is possibility to eliminate oscillatory behaviors of the reaction using higher power of microwave. The possibility of controlling non-linear reaction using microwave was shown since microwave can easily travel through oil phase and reach water phase.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.772-775
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• 2006

Cinnamate polymers are well known photoreactive polymers due to [2+2] cycloaddition reaction of cinnamate side group. In this work, we have found that the cinnamate side groups could be also reacted by thermal energy, and this reaction is presumed to attribute to the radical reaction of carbon double bond in the cinnamate groups. Contrary to the photocycloaddition reaction of the cinnamate side groups, the thermal reaction of cinnamate side group was closely related to the flexibility of polymer backbone. The difference of the mechanism between the photocycloaddition reaction and thermal crosslinking reaction was confirmed by $^1H-NMR$$ and $^{13}C-NMR$ analysis of the model compound.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.833-841
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• 2021

During the postulated severe accident of nuclear reactor, eutectic reaction leads to low-temperature melting of fuel cladding and early failure of core structure. In order to model eutectic melting with the moving particle semi-implicit (MPS) method, the eutectic reaction model is developed to simulate the eutectic reaction phenomenon. The coupling of mass diffusion and phase diagram is applied to calculate the eutectic reaction with the uniform temperature. A heat transfer formula is proposed based on the phase diagram to handle the heat release or absorption during the process of eutectic reaction, and it can combine with mass diffusion and phase diagram to describe the eutectic reaction with temperature variation. The heat transfer formula is verified by the one-dimensional melting simulations and the predicted interface position agrees well with the theoretical solution. In order to verify the eutectic reaction models, the eutectic reaction of uranium and iron in two semi-infinite domains is simulated, and the profile of solid thickness decrease over time follows the parabolic law. The modified MPS method is applied to calculate Transient Reactor Test Facility (TREAT) experiment, the penetration rate in the simulations are agreeable with the experiment results. In addition, a hypothetical case based on the TREAT experiment is also conducted to validate the eutectic reaction with temperature variation, the results present continuity with the simulations of TREAT experiment. Thus the improved method is proved to be capable of simulating the eutectic reaction in the severe accident.

• Journal of Biomedical Engineering Research
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• v.33 no.4
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• pp.163-168
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• 2012

Elderly women are reported to have greater risk of falls. The purpose of this paper was to investigate the possible gender differences in the reaction performance of ankle joint muscles, which have dominant role in the control of sagittal plane balance. Twenty-six elderly men and women with comparable mean age participated in this study. Reaction times to the audible beeps were measured in the tibialis anterior muscle and gastrocnemius muscle. Reaction time variables included premotor time, electromechanical delay and total reaction time. Gender difference in each reaction time was investigated by independent t-test. In both muscles, premotor time was longer in men but the electromechanical delay was longer in women (p < 0.05). Resulting total reaction time was longer in men in tibialis anterior muscle (p < 0.01) and it tended to be longer in men also in gastrocnemius muscle (p = 0.25). The results demonstrates that the overall reaction performances of elderly women is better than or comparable to those of elderly men in ankle joint muscles. This suggests that the reaction performance of ankle muscles is hardly the cause of the greater risk of falls in elderly women.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.2
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• pp.103-108
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• 1998

A hydrophobic substrate triolein was hydrolyzed by lipase in a mono-phase reaction system containing cyclodextrin(CD) as emulsifier. The triolein was transformation to an emulsion-like state in the CD containing reaction system in contrast to the oil-droplet like state without CD due to the formation of an inclusion complex between the lipids and CDs. The hydyrolysis reaction increased substantially in the CD containing reaction system, and the optimum reaction conditions including the amount of lipase, ${\beta}$-CD concentration, and mixing ratio of triolein and ${\beta}$-CD, were determined. The performance of the enzyme reaction in a mono-phase reaction system was compared with that of a two-phase reaction system which used water immiscible hexane as the organic solvent. The role of a CD in the mono-phase reaction system was elucidated by comparing the degree of the inclusion complex formation with triolein and oleic acid, Km and Vmax values, and product inhibition by oleic aicd in aqueous and CD containing reaction systems. The resulting enhanced reaction seems to be caused by two phenomena; the increased accessibility of lipase to triolein and reduced product inhibition by oleic acid through the formation of an inclusion complex.

• Geomechanics and Engineering
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• v.13 no.5
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• pp.757-774
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• 2017

The subgrade reaction modulus of a large mat foundation was investigated by using a numerical analysis and a field case study. The emphasis was on quantifying the appropriate method for determining the subgrade reaction modulus for the design of a flexible mat foundation. A series of 3D non-linear FE analyses are conducted with special attention given to the subgrade reaction modulus under various conditions, such as the mat width, mat shape, mat thickness, and soil condition. It is shown that the distribution of the subgrade reaction modulus is non-uniform and that the modulus of subgrade reaction at both the corners and edges should be stiffer than that at the center. Based on the results obtained, a simple modification factor for the subgrade reaction modulus is proposed depending on the relative positions within the foundation in weathered soil and rocks.

• Environmental Engineering Research
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• v.17 no.4
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• pp.217-225
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• 2012

In this study, the treatability of two target contaminants during the Fenton reaction, n-hexadecane and 1-methylnaphthalene, was evaluated as a function of the amounts of $FeCl_2$ and $H_2O_2$ injected into open and closed reaction systems. In the Fenton reaction of n-hexadecane and 1-methylnaphthalene, the mass recovery of the target contaminants was above 95% in the closed system. However, when the Fenton reaction was performed with high amounts of $H_2O_2$ and $FeCl_2$ injected in the open system, a reduction of approximately 40% of the initial mass of 1-methylnaphthalene was observed. This trend may be explained by the unique physical properties of 1-methylnaphthalene, which has higher volatility than n-hexadecane. Further, this trend was well correlated with the rise in high temperature at the initial reaction stage. Considering the mass recovery of the two target contaminants, the reaction temperature, and the residual concentration of $H_2O_2$ at different amounts of $FeCl_2$ and $H_2O_2$ injected, it can be suggested that the Fenton reaction should be performed with controlled conditions that can provide a suitable reaction environment between oxidant and contaminants.

• Journal of the Korean Chemical Society
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• v.67 no.1
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• pp.28-32
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• 2023

The reaction conditions optimization, including the temperature of the reaction, amount of catalyst required, and reaction time for the linoleic acids (LAs) and conjugated linoleic acids (CLAs) production by catalytic dehydration of castor oil via saponification was investigated by response surface methodology (RSM). It was confirmed that all three parameters (temperature, time, and amount of catalyst) were influential factors in isolating LAs and CLAs. When the temperature was increased, the iodine value increased, and the reaction time and catalyst amount increased. The optimal reaction conditions were: 240 ℃, 2.2 h reaction time, and 7 wt% catalyst amount. The maximum iodine value reached 156.25 with 91.69% conversion to the essential fatty acids.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.724-727
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• 2002

2,7-dibromo-9, 9-dialkyl-substituted-fluorene derivatives were prepared by the alkylation of 2,7-dibromofluorene with various alkyl groups under two-phase phase transfer catalysis (PTC) conditions, as monomers for synthesizing poly(dialkylfluorene)s. Tetra-nbutylammonium hydrogen sulfate (TBAHS) was used as a phase transfer catalyst to enhance nucleophilic substitution. In addition, NaOH in water (25M) was used as a base to generate anions. Compared to conventional alkylation using butyllithium(BuLi), the reaction using the PTC technique attained high selectivity and substantial conversion of reactants, due to the enhanced reaction rate, while the reaction was carried out under moderate conditions. An approximately 90% yield was obtained from the reaction and the reaction time was remarkably reduced. 2,7-dibromo-9,9-dihexyl-fluorene, 2,7-dibromo-9,9-dioctyl-fluorene, and 2,7-dibromo-9,9-di(2-ethylhexyl)-fluorene were effectively synthesized by phase transfer catalytic reaction.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.288-291
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• 2005

Resol type phenol-formaldehyde (PF) resin was synthesized by addition reaction of formaldehyde (F) and phenol (P). And the PF resin was synthesized by condensation reaction in which water was removed. In this work, we studied the influence of experimental parameters in the addition reaction, such as F/P mole ratio, amount of catalyst, reaction temperature, reaction time, and so on. Also, we studied the influence of molecular weight and viscosity of PE resin as a function of condensation time. As a result, in addition reaction, the reaction time decreased remarkably as the catalyst concentration increased, and the time decreased with increasing reaction temperature at a constant catalyst concentration. Also, in condensation reaction, the viscosity of resol type PF resin increased from 1500 to 9000 cps as a function of condensation time; molecular weight showed from 500 to 1100 g/mol.