• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.90-96
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• 2018

This paper proposed data driven techniques to forecast the time point of water management of the water reservoir without measuring manganese concentration with the empirical data as Juam Dam of years of 2015 and 2016. When the manganese concentration near the surface of water goes over the criteria of 0.3mg/l, the water management should be taken. But, it is economically inefficient to measure manganese concentration frequently and regularly. The water turnover by the difference of water temperature make manganese on the floor of water reservoir rise up to surface and increase the manganese concentration near the surface. Manganese concentration and water temperature from the surface to depth of 20m by 5m have been time plotted and exploratory analyzed to show that the water turnover could be used instead of measuring manganese concentration to know the time point of water management. Two models for forecasting the time point of water turnover were proposed and compared as follow: The regression model of CR20, the consistency ratio of water temperature, between the surface and the depth of 20m on the lagged variables of CR20 and the first lag variable of max temperature. And, the Box-Jenkins model of CR20 as ARIMA (2, 1, 2).

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.49-56
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• 1985

This study consists of instrumenting and running tests on variable compression engines and measuring the following combustion characterics: (a)flame speed, (b) emission and (c)performance parameter such as power and economy. The results were as follows: 1) The phase separation diagram of substitute fuels were obtained from phase separation experiment. 2) The flame propagation speed of substitute fuels were higher than gasoline and increased with increasing methanol weight percent of substitute fuels. 3) BEMP of substitute fuels was slightly less than that of gasoline but in the range of small weight percent, BEMP was compatible to gasoline. 4) Concentration of NOx decreased significantly with delaying spark advancing time. Also, it decreased for rich equivalence ratio but increased with high compression ratio. In general, NOx concentration was much lower than that of gasoline. 5) Concentration of HC and CO increased for rich equivalence ratio. Also it was lower than that of gasoline.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.448-454
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• 2007

Hydrothermal synthesis was conducted with starting material as Barium hydroxide and hydrous titania ($TiO_2{\cdot}xH_2O$) to obtain barium titanate fine Powder. The conversion, crystal structure and properties of as-prepared powder were investigated according to reaction temperature, time and concentration. The effect of variables on conversion was in order of time < temperature < concentration and the maximum conversion reached to 99.5% in the case of hydrothermal synthesis at $180^{\circ}C$ for 2 h with 2.0 M reactant concentration. At low concentration such as 0.25 M, formation of unreacted $BaCO_3$ and $TiO_2$ was not inevitable at even high reaction temperature and these components converted into $BaTi_2O_5$ at high temperature and remained as impurity. As concentration of reactant increased, the size of as-synthesized $BaTiO_3$ powder deceased and Ba/Ti molar ratio approached into 1, showing Ba/Ti ratio of $1{\pm}0.005$ for reaction at $180^{\circ}C$ for 2 h with 2.0 M concentration.

• Journal of Environmental Science International
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• v.12 no.12
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• pp.1321-1327
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• 2003

Two different kinds of cases, with and without addition of noncrystalline silica to the Hadong kaolin were studied to obtain useful information on the synthesis of zeolite. The research was carried out to investigate the formation area and the crystalized degree of zeolite according to a synthetic time, the water content of raw material mixture, KOH concentration, and stirring intensity. In the case of without addition of noncrystalline silica to the Hadong kaolin and the low concentration range of KOH, the structure of the kaolin was not changed. However, when the mole ratio of K2O/SiO$_2$ in natural kaolin was increased, Linde-L zeolite and unknown structure of kaolins, U-1 and U-2 were produced. While in the high concentration range of KOH, the unknown structure of kaolins, U-6 and U-2, were produced and the production rate of U-6 was increased with the increased of K2O/SiO$_2$ mole ratio. In the case of with addition of noncrystalline silica to the Hadong kaolin and treatment with KOH hydrothermal processing, ZSM-5, ZSM-35, and Linde-L zeolites and the mixture of unknown structure of zeolites, U-1, U-2, U-3, and U-4, were obtained. Both cases demonstrated that the synthesis of zeolite from the Hadong kaolin was highly influenced by KOH concentration of raw material mixture.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.5
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• pp.545-552
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• 2000

Eight aromatic hydrocarbons were quantified in a newly constructed building before occupancy during the period of November 1997 to January 1998. Air samples were collected in 6 L stainless steel canisters for 8 hours based on working hour. It was found that the measured total concentration of aromatic hydrocarbons decreases rapidly with time up to a steady-state value. However, the fractions for each aromatic hydrocarbon were greatly changed with time. The concentration ratios of indoor to outdoor for aromatic hydrocarbons are greater than 1 during early period of the measurement, and the ratios decrease with time. The concentrations of toluene, m+p-xylene, ethylbenzene, and o-xylene are much higher than those of styrene, 1, 2, 4-trimethylbenzene, and 1, 3, 5-f trimethylbenzene in indoor air. The concentration fractions of m+p-xylene, ethylbenzed, and o-xylene in indoor air are about twice as hight as those in outdoor air measured during the similar period. It was concluded that the aromatic hydrocarbons were emitted from building materials, paints, and adhesives in an-built building.

• The Journal of Natural Sciences
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• v.10 no.1
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• pp.103-109
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• 1998

We studied on the decoloring effect of viscose rayon by vapor type ozone processing using ozone's strong oxidation. When ozone is generated, it becomes high concentration in vapor state, but in the insolving process with water, there are a lot of lose of ozone. As a result, a study using ozone in vapor-high concentration state is needed. So, in this paper, vapor type ozone processing is used unlike previous ozone treatment method-an aqueous solution method-to get a good effect from shortening the processing time. When vapor type ozone processing was directly treated to fabrics, high concentration ozone was generated then in a short time oxidized a dye existed in fabrics and finally decolored it. As vapor type ozone did not directly response to an organic dye, viscose rayon's decolorization was to be studied by changing pick up ratio(60%, 50%, 40%, 30%, 20%) using water as a medium. When pick up ratio of water was 40%, fabric's whiteness was improved but tensile strength and elongation were reduced. So 60 minutes was assumed as the most adjust time to minimize the reduction of fabric's tensile strength and elongation moreover of maximize the improvement of whiteness.

• Archives of Pharmacal Research
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• v.29 no.12
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• pp.1179-1186
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• 2006

Cross-linked starch microspheres were prepared using different kinds of cross-linking agents. The influence of several parameters on morphology, size, swelling ratio and drug release rate from these microspheres were evaluated. These parameters included cross-linker type, concentration and the duration of cross-linking reaction. Microspheres cross-linked with glutaraldehyde had smooth surface compared with those prepared with epichlorhydrine or formaldehyde. The particle size increased with increasing the cross-linking time and increasing the drug loading. Swelling ratio of the particles was a function of cross-linker type but not the concentration or time of cross-linking. Drug release from starch microspheres was measured in phosphate buffer and also in phosphate buffer containing a-amylase. Results showed that microspheres cross-linked with epichlorhydrine released all their drug content in the first 30 minutes. However, cross-linking of the starch microspheres with glutaraldehyde or formaldehyde decreased drug release rate. SEM and drug release studies showed that cross-linked starch microspheres were susceptible to the enzymatic degradation under the influence of alpha-amylase. Changing the enzyme concentration from 5000 to 10,000 IU/L, increased drug release rate but higher concentration of enzyme (20,000 IU/L) caused no more acceleration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1C
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• pp.19-24
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• 2006

In this study, centrifugal model tests were performed to evaluate the stress sharing between SCP and surrounding clayey soil at composite ground improved by sand compaction pile with the low area replacement ratio. The SCPs were formed by the "frozen pile" method and pressure cells were installed on pile and surrounding clayey soil to observe stress sharing characteristics. As a result of centrifugal tests, it is shown that the value of stress concentration ratio is mainly affected by area replacement ratio, loading condition and elapsed time.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.27-38
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• 2005

An experimental investigation of the gas-phase photooxidation of toluene-NO$_{x}$-air mixtures at sub-ppm concentrations has been carried out in a 6.9 ㎥, indoor smog chamber irradiated by blacklights. Measured parameters in the toluene-NO$_{x}$ experiments included aerosol, $O_3$, NO, NO$_2$, NO$_{x}$ CO, SO$_2$ toluene, and air temperature. The initial toluene concentration ranged from 225 ppb to 991 ppb and the initial concentration ratio of toluene/NO$_{x}$ in ppbC/ppb was in the range of 5～20. It was found that the variation of aerosol number concentration with irradiation time caused by the photooxidation of toluene-NO$_{x}$-air mixtures depended on the initial toluene concentration for similar concentration ratio of toluene/NO$_{x}$. The dependency of initial toluene concentration on the photooxidation of toluene-NO$_{x}$-air mixtures for toluene/NO$_{x}$= 5～6 seemed to be opposite to that for toluene/NO$_{x}$=10～11. The maximum number concentration of aerosols formed by photooxidation and the aerosol yield depended on both initial toluene concentration and initial concentration ratio of toluene/NO$_{x}$. In this study, the aerosol yield, defined as aerosol formed per unit toluene consumed, was found to be 0.01～0.16.und to be 0.01～0.16.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.70-77
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• 1957

4,5-Diphenyl Imidazolone is synthesized from Benzoin, Urea, and Acetic acid catalyser. Nowadays, it is being used as an optical bleaching agent for wool and nylon textiles. Up to now, only one process of synthesis has been known. In order to find out the best conditions governing the yield were examined under various catalysers and conditions. In this experiment, the summary of results were as follows. a. On Acetic acid catalyser. The maximum yield conditions were mol ratio (Benzoin: Urea: Acetic acid) 1 : 2 : 14, Acetic acid concentration 99.9%. Reaction temperature 115$^{\circ}$. Under reaction time of 2 hours, above yield was 96.4%. b. On Mineral acid Catalyser. In using of Sulfonic acid, the color of solution was changed dark purlish black. With other mineral acid catalysers, in spite of increasing of temperature, it was proved that Benzoin floats on the solution, so that this reaction could not be continue. c. On Phosphoric acid catalyser. It was made clear that it can not be used for this reaction. d. On Sodium hydroxide catalyser. As one of Alkali catalyser, Sodium hydroxide was examined but this was unsuitable substance for this reaction. e. On Formic acid catalysers. The maximum yield conditions were mol ratio (Benzoin: Urea: Formic acid) 1: 2: 30. Formic acid concentration 85.%. Reaction temperature 150∼110$^{\circ}$. Under reaction time of 90 minutes, the best yield was 87%. Hereby, it was proved that organic acids such as Acetic acid and Formic acid can be used. When using Acetic acid, the yield was better than Formic acid, but it takes longer reaction time than Formic acid. About the fluorescent effect, the temperature of dye-bath must not be over 904,5-Diphenyl Imidazolone is synthesized from Benzoin, Urea, and Acetic acid catalyser. Nowadays, it is being used as an optical bleaching agent for wool and nylon textiles. Up to now, only one process of synthesis has been known. In order to find out the best conditions governing the yield were examined under various catalysers and conditions. In this experiment, the summary of results were as follows. a. On Acetic acid catalyser. The maximum yield conditions were mol ratio (Benzoin: Urea: Acetic acid) 1 : 2 : 14, Acetic acid concentration 99.9%. Reaction temperature 115$^{\circ}$. Under reaction time of 2 hours, above yield was 96.4%. b. On Mineral acid Catalyser. In using of Sulfonic acid, the color of solution was changed dark purlish black. With other mineral acid catalysers, in spite of increasing of temperature, it was proved that Benzoin floats on the solution, so that this reaction could not be continue. c. On Phosphoric acid catalyser. It was made clear that it can not be used for this reaction. d. On Sodium hydroxide catalyser. As one of Alkali catalyser, Sodium hydroxide was examined but this was unsuitable substance for this reaction. e. On Formic acid catalysers. The maximum yield conditions were mol ratio (Benzoin: Urea: Formic acid) 1: 2: 30. Formic acid concentration 85.%. Reaction temperature 150∼110$^{\circ}$. Under reaction time of 90 minutes, the best yield was 87%. Hereby, it was proved that organic acids such as Acetic acid and Formic acid can be used. When using Acetic acid, the yield was better than Formic acid, but it takes longer reaction time than Formic acid. About the fluorescent effect, the temperature of dye-bath must not be over 90$^{\circ}$. and the ratio of 4,5-Diphenyl Imidazolone and water should be from 1:50000. to 1:10000. It proved that the best effect on textiles, and the best condition were dye-temperature near 704,5-Diphenyl Imidazolone is synthesized from Benzoin, Urea, and Acetic acid catalyser. Nowadays, it is being used as an optical bleaching agent for wool and nylon textiles. Up to now, only one process of synthesis has been known. In order to find out the best conditions governing the yield were examined under various catalysers and conditions. In this experiment, the summary of results were as follows. a. On Acetic acid catalyser. The maximum yield conditions were mol ratio (Benzoin: Urea: Acetic acid) 1 : 2 : 14, Acetic acid concentration 99.9%. Reaction temperature 115$^{\circ}C$. . Under reaction time of 2 hours, above yield was 96.4%. b. On Mineral acid Catalyser. In using of Sulfonic acid, the color of solution was changed dark purlish black. With other mineral acid catalysers, in spite of increasing of temperature, it was proved that Benzoin floats on the solution, so that this reaction could not be continue. c. On Phosphoric acid catalyser. It was made clear that it can not be used for this reaction. d. On Sodium hydroxide catalyser. As one of Alkali catalyser, Sodium hydroxide was examined but this was unsuitable substance for this reaction. e. On Formic acid catalysers. The maximum yield conditions were mol ratio (Benzoin: Urea: Formic acid) 1: 2: 30. Formic acid concentration 85%. Reaction temperature 150∼110$^{\circ}C$. Under reaction time of 90 minutes, the best yield was 87%. Hereby, it was proved that organic acids such as Acetic acid and Formic acid can be used. When using Acetic acid, the yield was better than Formic acid, but it takes longer reaction time than Formic acid. About the fluorescent effect, the temperature of dye-bath must not be over 90$^{\circ}C$. and the ratio of 4,5-Diphenyl Imidazolone and water should be from 1:50000. to 1:10000. It proved that the best effect on textiles, and the best condition were dye-temperature near 70$^{\circ}C$. and dye-time 15 minutes. . and dye-time 15 minutes. . and the ratio of 4,5-Diphenyl Imidazolone and water should be from 1:50000. to 1:10000. It proved that the best effect on textiles, and the best condition were dye-temperature near 70$^{\circ}C$. and dye-time 15 minutes.