• 한국응용과학기술학회지
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• 제18권4호
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• pp.249-253
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• 2001

A proposed method of determining the composition of mixed micelles in equilibrium with monomer of known composition is described. The systems were sodium ${\alpha}-sulfonated$ dodecanoyl ethyl esther (${\alpha}-SR_{12}Et$) or sodium dodecyl sulfate(SDS)-polyoxyethylene 23 lauryl ether (Brij 35) un water and in 0.1M sodium chloride solution at $25^{\circ}C$. This technique applies the Gibbs-Duhem equation to the mixed micelles, which is treated as a pseudophase. This proposed methodology, which needs only critical micelle concentration data as a function of monomer composition, is applied to an anionic/nonionic surfactant pair. The calculated monomer-micelle equilibrium is found to be very similar to the much-used regular solution for nonideal systems.

• 한국주조공학회지
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• 제20권2호
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• pp.129-140
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• 2000

This study aims at the phase-field modeling of the phase transformation in graphitization of the cast iron. As the first step, we constructed a phase-field model including the phases with negligible solubility. Under the dilute regular solution approximation, a simplified version of the phase-field model was obtained, which can be used for the phase transformation related with the stoichiometric phases. The results from the numerical calculation of the phase-field model was in good agreement with the exact analytic solution. The compositional shift due to Gibbs-Thomson effect can be reproduced within 0.5% error in the numerical calculation. The interface velocity, whereas, in numerical calculation of phase-field model appeared to be 15% larger than that from the analytic solution. This error is due to the shift of the interface position in phase-field model from the position with ${\phi}=0.5$.

• Bulletin of the Korean Chemical Society
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• 제24권6호
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• pp.751-756
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• 2003

We have investigated the solvent effects on Δlog $K_s$ (the difference of stability constant of binding) and the relative free energies of binding of $La^{3+} and Nd^{3+}$ ions to 18-crown-6 by a Monte Carlo simulation of statistical perturbation theory (SPT) in diverse solvents. We compared relative binding Gibbs free energies and the differences in stability constant (Δlog $K_s$) of binding of $La^{3+} and Nd^{3+}$ ions to 18-crown-6 in $CH_3OH$ in this study with the experimental. There is a good agreement between our study and the experimental. We noted that Borns function of the solvents, the electron pair donor properties of the solvent, the radii of host and guest and the differences in solvation dominate the differences in the stability constant (Δlog $K_s$) as well as the relative free energies of binding of TEX>$La^{3+} to Nd^{3+}$ ions to 18-crown-6. The results of this study appear promising for providing the association properties of crown ethers with alkaline earth metals among polar solvents and the less polar or non-polar solvents.

• Bulletin of the Korean Chemical Society
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• 제11권4호
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• pp.309-313
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• 1990

The rates of solvolysis of trans-$[Co(N-eten)_2Cl_2)$+ (N-eten; N-ethylethylenediamine) have been investigated using spectrophotometric method in binary aqueous mixtures containing methyl alcohol, isopropyl alcohol, t-butyl alcohol, ethylene glycol and glycerol. The values of ${\Delta}H^{\neq}$ and ${\Delta}S^{\neq}$ obtained from temperature effect on the rate constants were $80{\sim}84 kJmol^{-1}$ and $- 28{\sim} - 45 JK^{-1}mol^{-1}.$ Extrema found in the variation of the enthalpy and entropy of activation with solvent composition correlated very well with extrema in the variation of the physical properties of mixture which relate to sharp change in the solvent structure. The reaction mechanism was discussed in terms of correlation diagrams involving the exess molar Gibbs function of mixing for the binary mixtures. The behavior of this cobalt(Ⅲ) complex was compared with that of t-butyl chloride. The application of free energy cycle to the process initial state to transition state in water and in the mixture showed that the solvation of transition state had dominant effect on the rates in the mixtures. It was found that $S_N1$ character was increased with increasing the content of co-solvent in the mixture.

• Communications for Statistical Applications and Methods
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• 제29권1호
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• pp.65-83
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• 2022

Although various statistical methods have been developed to map time-dependent genetic factors, most identified genetic variants can explain only a small portion of the estimated genetic variation in longitudinal traits. Gene-gene and gene-time/environment interactions are known to be important putative sources of the missing heritability. However, mapping epistatic gene-gene interactions is extremely difficult due to the very large parameter spaces for models containing such interactions. In this paper, we develop a Gaussian process (GP) based nonparametric Bayesian variable selection method for longitudinal data. It maps multiple genetic markers without restricting to pairwise interactions. Rather than modeling each main and interaction term explicitly, the GP model measures the importance of each marker, regardless of whether it is mostly due to a main effect or some interaction effect(s), via an unspecified function. To improve the flexibility of the GP model, we propose a novel grid-based method for the within-subject dependence structure. The proposed method can accurately approximate complex covariance structures. The dimension of the covariance matrix depends only on the number of fixed grid points although each subject may have different numbers of measurements at different time points. The deviance information criterion (DIC) and the Bayesian predictive information criterion (BPIC) are proposed for selecting an optimal number of grid points. To efficiently draw posterior samples, we combine a hybrid Monte Carlo method with a partially collapsed Gibbs (PCG) sampler. We apply the proposed GP model to a mouse dataset on age-related body weight.

• Asian-Australasian Journal of Animal Sciences
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• 제32권8호
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• pp.1077-1083
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• 2019

Objective: Sow longevity is important for efficient and profitable pig farming. Recently, there has been an increasing interest in social genetic effect (SGE) of pigs on stress-tolerance and behavior. The present study aimed to estimate genetic correlations among average daily gain (ADG), stayability (STAY), and number of piglets born alive at the first parity (NBA1) in Korean Yorkshire pigs, using a model including SGE. Methods: The phenotypic records of ADG and reproductive traits of 33,120 and 11,654 pigs, respectively, were evaluated. The variances and (co) variances of the studied traits were estimated by a multi-trait animal model applying the Bayesian with linear-threshold models using Gibbs sampling. Results: The direct and SGEs on ADG had a significantly negative (-0.30) and neutral (0.04) genetic relationship with STAY, respectively. In addition, the genetic correlation between the social effects on ADG and NBA1 tended to be positive (0.27), unlike the direct effects (-0.04). The genetic correlation of the total effect on ADG with that of STAY was negative (-0.23) but non-significant, owing to the social effect. Conclusion: These results suggested that total genetic effect on growth in the SGE model might reduce the negative effect on sow longevity because of the growth potential of pigs. We recommend including social effects as selection criteria in breeding programs to obtain satisfactory genetic changes in both growth and longevity.

• 한국염색가공학회지
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• 제14권4호
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• pp.214-222
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• 2002

In order to give a silk-like touch to PET fabrics, the PET fabrics were treated with NaOH alkaline solution in various conditions. In alkaline treatment, the liquor flow type pilot weight reduction apparatus with magnetostrictive ultrasonic transducer was used for the study. The weight loss of PET fabrics hydrolyzed in 4% and 6% NaOH solution, at $95^\circ{C}$ and $99^\circ{C}$ for 60min. with ultrasonic application showed 3.7~4.6% higher than that of treated fabric without ultrasonic application. From the difference of specific weight loss, the treatment condition of the maximum of hydrolyzation effect appeared at $95^\circ{C}$ in $4^\circ{C}$ and at $90^\circ{C}$ in 6% NaOH solution, respectively. During the alkali hydrolysis of PET fabrics, the decomposition rate constant(k) increased exponentially with the treatment temperature and were not related with ultrasonic cavitation. The activation energy$(E_a)$ in decomposition of PET fabrics were 21.06kcal/mol with ultrasonic application and 21.10kcal/mol without ultrasonic application. The ultrasonic application gave a little higher value of the activation entropy$(\Delta{S}^\neq)$ and a little lower value of Gibbs free energy$(\Delta{S}^\neq)$ compared with not used ultrasonic apparatus.

• Environmental Engineering Research
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• 제17권3호
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• pp.125-132
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• 2012

The removal of Cd(II) and Cu(II) from aqueous solution by an agricultural solid waste biomass prepared from Moringa oleifera bark (MOB) was investigated. The biosorbent was characterized by Fourier transform infrared spectroscopy and elemental analysis. Furthermore, the effect of initial pH, contact time, biosorbent dosage, initial metal ion concentration and temperature on the biosorption of Cd(II) and Cu(II) were studied using the batch sorption technique. Kinetic studies indicated that the biosorption process of the metal ions followed the pseudo-second order model. The biosorption data was analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models. Based on the Langmuir isotherm, the maximum biosorption capacities for Cd(II) and Cu(II) onto MOB were 39.41 and 36.59 mg/g at 323 K, respectively. The thermodynamic parameters, Gibbs free energy (${\Delta}G^o$), enthalpy (${\Delta}H^o$), and entropy (${\Delta}S^o$) changes, were also calculated, and the values indicated that the biosorption process was endothermic, spontaneous and feasible in the temperature range of 303-323 K. It was concluded that MOB powder can be used as an effective, low cost, and environmentally friendly biosorbent for the removal of Cd(II) and Cu(II) ions from aqueous solution.

• 한국응용과학기술학회지
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• 제17권2호
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• pp.132-138
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• 2000

Excess enthalpies ($H^{E}$) were measured by isothermal flow calorimetry for the nonionic amphiphile 2-butoxyethanol/water mixtures at 10 different temperatures (48.5 to $70^{\circ}C$) around and above the lower consolute solution temperature, $T_{lc}$. $H^{E}$ exhibits U-shape for the binary mixtures, and is large and negative which reflects substantial interaction between two chemical species. When the commonly used, semi-empirical Redlich-Kister (RK) polynomials were fitted to the measured $H^{E}$, plots of $H^{E}$ vs. weight fraction provided more accurate fitting with fewer parameters than conventionally drawn $H^{E}$ vs. mole fraction plots. This was due to the enhanced symmetry of $H^{E}$ vs. weight fraction plots. Using the fitted Redlich-Kister polynomials and the Gibbs-Helmholtz relation, temperature dependence of the activity coefficients were found and compared to the values determined from vapor-liquid equilibria. The activity coefficients were in the range of one to three, indicating that the binary system deviates from ideality but not substantially. They slightly depended on temperature and the temperature effect was equivalent to 10 % change in the activity coefficients.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.545-548
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• 2009

최근 천연가스 개발의 중요성이 대두되면서 심해저 퇴적층에 존재하고 있는 천연가스 하이드레이트 개발에 많은 연구가 진행되고 있다. 본 연구에서는 심해저 퇴적층에 부존하는 가스 하이드레이트 조건과 유사하게 하기위해 3 wt% 농도의 염수를 다공성 실리카 젤 기공에 넣어 사용하였다. 기공의 직경에 따른 영향을 알아보기 위해 기공 직경이 각각 6.0, 15.0, 30.0 nm인 실리카 젤을 사용하여, 천연가스 주성분인 에탄, 프로판, 메탄+프로판 하이드레이트의 3상 (H-Lw-V) 평형을 측정하였다. 그 결과 기공의 크기가 작아질수록 각각의 벌크 상태의 에탄, 프로판, 메탄+프로판 하이드레이트에 비해 하이드레이트의 평형조건이 온도는 낮아지고 압력이 높아지는 저해효과가 커짐을 알 수 있었다. 실험값으로 부터 기공 내의 물과 하이드레이트상 사이의 계면장력 값을 Gibbs-Thomson식에 의해 구할 수 있으며, 열역학 계산을 통하여 실험값과 비교하였다. 본 연구에서 얻어진 결과는 심해저 천연가스 개발, 이산화탄소 심해저장 등의 가스 하이드레이트 응용 연구에 유용한 기초 자료가 될 것이다.