• Analytical Science and Technology
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• v.12 no.1
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• pp.68-74
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• 1999

The Concentrations of PCDDs/PCDFs and their precusors(chlorophenols, chlorobenzenes, PCB) were analyzed from the dioxin control device such as EP and SCR to know the emission patterns of these compounds and find the dioxin index compounds. The dioxin concentration increased 7 times in outlet part than inlet part of EP and the concentration of CBs, CPs and PCBs also were increased through this control device. These phenomia may be related to the operating temperature of Electroprecipitator(EP), which the operating temperature is near the $300^{\circ}C$, the method of the decreasing the operating temperature need to consider to prevent the formation of these compounds. In the selected catalytic reactor with wet scrubber(SCR+WS), these compounds were removed after passing the device over 90% for CPs, 30~40% for CBs and 60% for PCBs. But, the systematic study have to perform to reduce the formation of PCDDs/PCDFs and precusors.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.383-396
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• 2007

The aim of this study was to measure the suprathreshold taste intensity for NaCl, sucrose, citric acid, and quinine HCl in elderly Korean women using a whole-mouth, sip-and-spit procedure, employing the method of magnitude matching. The results were analysed in terms of aging, menopause, and salivary flow rate. 31 elderly women (mean age; $50.8{\pm}5.1$ years) and 30 young women (mean age; $25.1{\pm}1.71$ years) were included for the study. Subjects were instructed to give nonmodulus magnitude estimates to the intensities of five concentrations each of sucrose, NaCl, citric acid, and quinine HCl; distilled water; 6 loudness level of a 1,000-Hz tone, using the same 9-point intensity scale. Each of the 21 taste stimuli and 6 auditory stimuli are presented in random order twice. The auditory function is used to assess the absolute intensity function of the subject's taste system. The results were as follows; 1. Comparing to young women, elderly women showed decreased taste intensities for lower concentration solutions of NaCl and sucrose. However, other solutions didn't show any difference in taste intensities between young and elderly women. 2. There were not significant difference in perceived taste intensities for NaCl, sucrose, citric acid, and quinine HCl between menopause and pre-menopause women in elderly women group. 3. There were not significant difference in perceived taste intensities for NaCl, sucrose, and quinine HCl between low salivation women and high salivation women in elderly women group. 4. The low salivation women in elderly group showed higher taste intensity for low concentration citric acid than high salivation women.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.551-557
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• 2019

Diagnosis of abnormal faults is essential for producing high quality products. The role of real-time diagnosis is quite increasing in the batch processes of producing high value-added products such as semiconductors, pharmaceuticals, and so forth. In this study, we evaluate the effect of variable selection and future-value estimation techniques on the performance of the diagnosis system, which is based on nonlinear classification and measurement data. The diagnostic performance can be improved by selecting only the variables that are important and have high contribution for diagnosis. Thus, the diagnostic performance of several variable selection techniques is compared and evaluated. In addition, missing data of a new batch, called future observations, should be estimated because the full data of a new batch is not available before the end of the cycle. In this work the use of different estimation techniques is analyzed. A case study on the polyvinyl chloride batch process was carried out so that optimal variable selection and estimation methods were obtained: maximum 21.9% and 13.3% improvement by variable selection and maximum 25.8% and 15.2% improvement by estimation methods.

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.8-15
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• 2004

A synthesis of new $\beta$-ketoacetoanilide chloride derivatives and anti fungal activity of these compounds library against 6 typical plant pathogens were described. Reaction of ketene dimer with chlorine followed by treatment of aniline derivatives gave 89 kinds of the corresponding $\beta$-ketoacetoanilide chlorides through combinatorial synthetic technology using Carousel Reaction Stations. Evaluation of antifungal activity (in vivo) of this chemical library against rice blast, rice sheath blight, tomato aray mold, tomato late blight, wheat leaf rust and barley powdery mildew was carried out. In general, $\beta$-ketoacetoanilide chlorides which present a substituent at 4 in phenyl group(para) of the compounds showed selective control activity against tomato late blight caused by Phytophthora infestans.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.512-515
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• 2008

The removal of iron from neodymium chloride solution was carried out by solvent extraction using Alamine 336 in kerosine. The effect of Alamine 336, hydrochloric acid and chloride ion concentrations on the extraction of Fe were studied. The results showed that Alamine 336 as an extractant for removal of iron was effective and the extraction percentage of iron was increased with increasing hydrochloric acid and chloride ion concentration in aqueous solution. The extraction of 99% of iron is attained at a ratio of A/O = 4 by distilled water. The stripping yield of iron from loaded Alamine 336 decreased with decreasing hydrochloric acid concentration in stripping solution.

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.929-936
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• 1993

Charge transfer complexes of some electron donors with one electron acceptor have been studied to investigate the maximum absorption wavelength and absorbance by UV-Vis spectrometer in three kinds of solvents, such as ethylene chloride, methylene chloride, and chloroform, at the temperature ranges of 16∼25$^{\circ}$C. 1,2,3,4-Tetrahydrocarbazole (THC), 2-methyl, 3-methyl, and 3-ethyl THC were selected as electron donors while chloranil was used as an electron acceptor in this study. It is found that these complexes forms 1 : 1 complexes, and their maximum absorbance and formation constants decreases with respect to the function of the polarity of solvent and temperature. The polarity of solvents and the temperature have been influenced on the formation constants, which were described using the thermodynamic properties. Moreover, the electronic and steric effects of electron donors have also been effects.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.162-171
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• 1993

This paper deals with the anisotropy of the mushy region during solidification process of a binary mixture. A theoretical model which specifies a permeability tensor in terms of pricipal values is proposed. Also, the governing equations are modified into convenient forms for the numerical analysis with the existing algorithm. Some test computations are performed for soeidification of aqueous ammonium chloride solution contained in a square cavity. Results show that not only the present model is capable of resolving fundamental characteristics of the tranport phenomena, but also the anisotropy significantly affects the interdendritic flow structure, i.e., double-diffusive convection and macrosegregation patterns.

• Journal of the Korean Chemical Society
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• v.25 no.1
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• pp.7-12
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• 1981

Solvolysis of $p-CH_3, p-H, p-Cl and p-NO_2$-benzenesulfonyl chlorides have heen studied in MeOH-MeCN mixtures. A nonlinear Hammett plot with a ratio order of p-NO_2 > p-CH_3 > p-H > p-Cl was obtained; the reaction was thought to proceed by an S_N1-S_N2 borderline mechanism. In all cases the reactivity was a maximum at 90∼95%(v) methanol, whereas methanol monomer selectivity defined as fi = \frac{k1}{ki}i (k1; observed pseudo-first order rate constant: ki; hypothetical rate constant for MeOH solution having the same polymer structure as in the pure MeOH) was a maximum at 80% methanol with a decreasing order of fi as p-NO_2 > p-Cl > p-H > p-CH_3.$ This was interpreted as the decrease in tightness of transition state; the larger the fi, the tighter is the MeOH attached to the substrate, and hence the more susceptible the substrate becomes to the approaching monomer methanol.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.698-703
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• 1998

The pervaporation experiments of aqueous solutions of trichloroethylene (TCE) and chlorobenzene (CB) through the silicone rubber (polydimethylsiloxane, PDMS) membrane were carried out and the effect of concentration polarization on the separation characteristics was investigated. The resistance-in-series model was used to explain the boundary layer resistance. It was clear that the concentration polarization phenomenon had a significant effect on the permeation behavior in the pervaporation separation of the trace organic chlorides from aqueous solutions. With the same membrane thickness, the permeation of TCE, which has a stronger affinity for the PDMS, appeared to be more influenced by the boundary layer resistance than that of CB. The effect of boundary layer resistance was reduced and the membrane resistance became dominant with increasing membrane thickness at a given hydrodynamic condition. The separation factor was increased to approach the intrinsic separation factor of the membrane with its thickness.

• Korean Journal of Materials Research
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• v.29 no.7
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• pp.412-424
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• 2019

Global fitting functions for Fe-selective chlorination in ilmenite($FeTiO_2$) and successive chlorination of beneficiated $TiO_2$ are proposed and validated based on a comparison with experimental data collected from the literature. The Fe-selective chlorination reaction is expressed by the unreacted shrinking core model, which covers the diffusion-controlling step of chlorinated Fe gas that escapes through porous materials of beneficiated $TiO_2$ formed by Fe-selective chlorination, and the chemical reaction-controlling step of the surface reaction of unreacted solid ilmenite. The fitting function is applied for both chemical controlling steps of the unreacted shrinking core model. The validation shows that our fitting function is quite effective to fit with experimental data by minimum and maximum values of determination coefficients of $R^2$ as low as 0.9698 and 0.9988, respectively, for operating parameters such as temperature, $Cl_2$ pressure, carbon ratio and particle size that change comprehensively. The global fitting functions proposed in this study are expressed simply as exponential functions of chlorination rate(X) vs. time(t), and each of them are validated by a single equation for various reaction conditions. There is therefore a certain practical merit for the optimal process design and performance analysis for field engineers of chlorination reactions of ilmenite and $TiO_2$.