• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.143-152
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• 2018

The process parameters of ethyl violet from aqueous solution by activated carbon adsorption were carried out as a function of pH, temperature, contact time, initial concentration and temperature. The adsorption equilibrium data can be described well by the Langmuir and Freundlich isotherm models. Base on Langmuir constant ($R_L=0.0343{\sim}0.0523$) and Freundlich constant (1/n=0.1633~0.1974), This process could be employed as effective treatment for adsorption of ethyl violet. The kinetic experimental results showed that the adsorption process can be well described with the pseudo second order model. Based on the positive enthalpy (6.505 kJ/mol), the adsorption of ethyl violet onto granular activated carbon is endothermic. The negative Gibbs free energy (-1.169~-1.681 kJ/mol) obtained indicates that the adsorption process is spontaneous and physisorption.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.581-586
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• 2015

Adsorption of Safranin using granular activated carbon from aqueous solution was investigated. Batch experiments were carried out as a function of adsorbent dose, initial concentration, contact time and temperature. The equilibrium adsorption data were fitted to Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Based on an estimated Langmuir separation factor, $R_L=0.183{\sim}0.254$ and a Freundlich separation factor, 1/n = 0.518~0.547, this process could be employed as an effective treatment method. Adsorption data were also modeled using the pseudo-first and second-order kinetic equations. It was shown that the pseudo-second-order kinetic equation could best describe the adsorption kinetics. The negative Gibbs free energy (${\Delta}G=-3.688{\sim}-7.220kJ/mol$) and positive enthalpy (${\Delta}H=33.126kJ/mol$) indicated that the adsorption process was spontaneous and endothermic.

• Journal of Sericultural and Entomological Science
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• v.27 no.2
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• pp.40-46
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• 1985

The equilibrium sorptions of C.I. Reactive Blue 19 and C.I. Reactive Blue 19 and C.I. Acid Blue 138 on Silk fibroin were investigated in the range of 50$^{\circ}C$, 70$^{\circ}C$, 90$^{\circ}C$ and to the pH range from 2.0 to 10.5. The results obtained are summarized as follows: 1) The amount of sorption of reactive dye was increased with the decrease of pH in dyeing solution and temperature. The amount of fixation showed the maximum value to pH 8.5 and 70$^{\circ}C$. 2) In acidic region, the sorption behavior of acid dye was similar to that of reactive dye, and Langmuir adsorption constant was increased with the decrease of pH. 3) Langmuir constant of both dyes was decreased with the increase of temperature, while standard affinity was increased. 4) The reaction of both dyes was exothermic and the values of $\Delta$S$^{\circ}$ were positive. 5) It was found that the sorption behavior of dyes against Silk fibroin could be described as Langmuir adsorption and Nernst distribution in lower pH region.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.704-710
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• 1988

This study was, firstly, to investigate water holding capacity in terms of variation of moisture sorption isotherms of seasoned squid treated with sodium lactate, glycerol, propylene glycol, sorbitol, mannitol, sodium benzoate, potassium sorbate and calcium propionate, and secondly, the effect of humectant treatments on storage stability was studied. The criteria for storage stability was based on three quality factors, namely, lipid oxiations, color development by non-enzymatic browning reactions and lipid oxidation, and mold growth. The effect of humectants on equilibrium moisture content was in the following increasing order; mannitol < sorbitol < sodium lactate < propylene glycol < glycerol. The experimental data indicated that sodium lactate has, in practice, potentially positive effect on processing of seasoned squid. During the storage period of 60 days, TBA values increased in all samples tested as humectants concentrations increased up to 10%. However, in the range of 1-7% sodium lactate treatment, the degree of lipid oxidation, browning reactions and mild growth were not high enough to affect the quality of seasoned squid, when compared with conventionally manufactured ones.

• Journal of Powder Materials
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• v.6 no.4
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• pp.314-319
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• 1999

The solid state reaction by mechanical alloying(MA) generally proceeds by lowering the free energy as the result of a chemical reaction at the interface between the two adjacent layers. However, Lee et $al.^{1-5)}$ reported that a mixture of Cu and Ta, the combination of which is characterized by a positive heat of mixing of +2kJ/mol, could be amorphized by mechanical alloying. This implies that there exists an up-hill process to raise the free energy of a mixture of pure Cu and la to that of an amorphous phase. It is our aim to investigate to what extent the MA is capable of producing a non-equilibrium phase with increasing the heat of mixing. The system chosen was the ternary $Cu_{30}Ta_{ 70-x}Mo_ x$ (x=35, 10). The mechanical alloying was carried out using a Fritsch P-5 planetary mill under Ar gas atmosphere. The MA powders were characterized by the X-ray diffraction with Cu-K $\alpha$ radiation, thermal analysis, electron diffraction and TEM micrographs. In the case of x=35, where pure Cu powders were mixed with equal amount of pure Ta and Mo powders, we revealed the formation of bcc solid solution after 150 h milling but its gradual decomposition by releasing fcc-Cu when milling time exceeded 200 h. However, an amorphous phase was clearly formed when the Mo content was lowered to x=10. It is believed that the amorphization of ternary $Cu_{30}Ta_{60}Mo_{10}$ powders is essentially identical to the solid state amorphization process in binary $Cu_{30}Ta_{70}$ powders.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.17 no.1
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• pp.41-67
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• 2006

The study is aimed to analyze the influence of FTA(Free Trade Agreement) between Korea and Japan on tourism and to suggest ways to increase tourists exchange between them by considering countermeasures of Korea's tourism based on the analysis and deriving political significance. The results of the study showed that the expected effects of FTA between Korea and Japan on tourism would overall be positive. There would be increases in employment and a higher rate of foreign-exchange earning, which plays a critical role in the cash flow. Therefore the government is required to prepare for several political measures as follows. First, ways to promote investment in tourism have to be established in a systematic way for FTA. Second, restructuring of tourism has to be considered seriously for tourism to be a high value-added industry after FTA. Third, the tourism information industry needs to be included in the tourism promotion act to promote e-tourism using information technology. In addition to this, an expansive cluster strategy needs to be developed, which relates tourism to other industries like culture and movies and to find ways to re-locate and re-educate manpower currently engaged in the tourism industry. Though the study investigated the influence of FTA on tourism through a practical analysis, it was restricted only to Korea. So the influence of FTA between Korea and Japan on the tourism of Japan should be included in further study. Furthermore, in subsequent studies the CGE(Computable General Equilibrium) model will be applied for objective analysis of the effects. Or measuring the ripple effect with multinational inter-industry relation table will be made for the study to make practical contributions to the development of government policy.

• Journal of the Korean Chemical Society
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• v.35 no.6
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• pp.636-644
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• 1991

The cationic polymerization of substituted oxethanes which have pendant energetic groups such as methoxy, azido, and nitrato are investigated theoretically using the semiempirical MINDO/3, MNDO, and AM1 methods. The nucleophilicity and basicity of substituted oxethanes can be explained by the negative charge on oxygen atom of oxetanes. The reactivity of propagation in the polymerization of oxetanes can be represented by the positive charge on carbon atom and the low LUMO energy of active species of oxetanes. The reaction of the energetic cyclic oxonium ion forms to the open chain carbenium ion forms is expected by computational stability energy of the oxonium and carbenium ion (about 10~20 kcal/mole) favoring the carbenium ion. The relative equilibrium concentration of cyclic oxonium and open carbenium ions is found to be a major determinant of mechanism, owing to the rapid equilibrium of these cation forms and the expectation based on clauclation that the prepolymer propagation step SN1 mechanism will be at least as fast as that for SN2 mechanism.

• Advances in environmental research
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• v.8 no.1
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• pp.23-38
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• 2019

In this study, Malachite Green (MG) dye removal from synthetic wastewaters by adsorption process using raw boron enrichment waste (BEW) and it's modifications (with acid and ultrasound) were aimed. 81% MG removal was obtained by BEW at optimum equilibrium conditions (time: 40 min., dosage: 500 mg/dm³, pH: 5-6, speed: 200 rpm, 298 K). MG removal from wastewaters using acid modified boron enrichment waste (HBEW) was determined as 82% at optimum conditions (time: 20 min., dosage: 200 mg/dm³, pH: 10, speed: 200 rpm, 298 K). For ultrasound modified BEW (UBEW), the highest MG removal percent was achieved as 84% at optimum conditions (time: 30 min, dosage: 375 mg/ dm³, pH: 8, speed: 200 rpm, 298 K). The equilibrium data of Malachite Green was evaluated for BEW, HBEW and UBEW adsorbents by using sorption isotherms such as Langmuir, Freundlich and Temkin models, out of which Langmuir model (R² = 0.971, 0.987 and 0.984) gave better correlation and maximum adsorption capacity was found to be 147.05, 434.78 and 192.30 mg/g, respectively. The adsorption kinetics followed the pseudo-second-order kinetic equation for sorption of MG onto wastes. A look at thermodynamic data reveals that natural sorption is spontaneous and endothermic because of free negative energy exchange and positive change in enthalpy, respectively. The results indicated that boron enrichment waste, and HCl and ultrasound-modified boron enrichment waste served as good alternative adsorbents in dye removal from wastewater.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.278-283
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• 2010

The cationic polymerization of oxolane high explosives which have pendant explosive groups such as azido, nitrato and hydrazino is investigated theoretically using the semiempirical MINDO/3, MNDO and AM1 methods. The nucleophilicity and basicity of oxolane high explosives can be explained by the negative charge on oxygen atom of oxolane. The reactivity of propagation in the polymerization of oxolane can be represented by the positive charge on carbon atom and the low LUMO energy of active species of oxolane. The reaction of the oxolane high explosives in oxonium ion form to the open chain carbenium ion form is expected by computational stability energy (17.950~30.197 kcal/mol) of the oxonium ion and carbenium ion favoring the carbenium ion. The relative equilibrium concentration of cyclic oxonium ion and carbenium ion is found to be a major determinant of mechanism, owing to the rapid equilibrium of these catoinic forms. Based on calculation, in the prepolymer propagation step, $S_N1$ mechanism will be at least as fast as that for $S_N2$ mechanism.

• Environmental and Resource Economics Review
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• v.26 no.3
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• pp.287-317
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• 2017

Asbestos has been actively used for various places. Since it was designated as the first grade carcinogen in the 1970s, strict regulations on using asbestos has been implemented globally. Considering long-term latent periods between asbestos exposure and environmental diseases, we analyze the time lag between asbestos consumption and the incidence of mesothelioma in Korea and estimate the long-run relationship. In addition, we conduct a comparative analysis on the effectiveness of asbestos regulations in the United Kingdom and the United States, which have accumulated long-term time-series observations. The latent period analysis indicates that the consumption of asbestos and the incidence of the disease are highly correlated in all three countries, being long-term lags of more than 30 years. Also, we find a long-run equilibrium relationship between asbestos consumption and the incidence of mesothelioma in the presence of long-term lags between the variables in all three countries. Furthermore, using a distributed lag model, asbestos consumption has statistically significant positive effects on mesothelioma with a long-term lag.