• Journal of the Korean Applied Science and Technology
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• v.17 no.2
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• pp.113-119
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• 2000

Alkylation of phenol with tert-butanol in the liquid phase on mordenite was studied. The influence of many reaction parameters such as calcination temperature, reaction temperature, t-butanol/phenol molar ratio on catalytic properties was discussed. The main products were 2,4-di-t-butylphenol, o-t-butylphenol, p-t-butylphenol, the last of these was wanted product. In order to enhance the selectivity of p-t-butylphenol, optimum conditions were recommended at $500^{\circ}C$ calcination temperature, $140^{\circ}C$ reaction temperature, 1.0 molar ratio of reactants over mordenite. P-t-butylphenol was formed with 90% isomer selectivity at optimum conditions after 4hr reaction. On the basis of the behavior obtained in the cases mentioned, optimum conditions and catalytic properties for t-butylation of phenol were provided.

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.967-973
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• 1993

The effect on the hydration of cement was that Cu and Pb reacted with alkali to form soluble hydrates at theinitial stage and then there followed a slow reaction forming insoluble metal hydroxides. These hydroxides were deposited on the surface of cement particles providing a barrier against further hydration. But as a slow reaction continued, the insoluble layers were eventually destroyed and the hydration reaction resumed. Thereafter, another retardation occured by restricting the polymerization of silicates, shown by FT-IR spectroscopy analysis. In the case of Cr, as its reaction with cement caused H2O, the coordinator of Cr complex, to replace or polymerize with OH-, the formation of Cr complex promoted the leakage of OH- and increased the heat of dissolution. So the total heat evolution during hydration was larger than that in the case of Pb or Cu. The retarding effect of heavy metal ions was in the order Pb>Cu>Cr.

• Korean Journal of Veterinary Research
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• v.15 no.1
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• pp.93-99
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• 1975

In order to compare the diagnostic value of Modified California Mastitis Test (MCMT), Modified Whiteside Test (MWT) and Resazurin Reduction Test (RRT) using the direct microscopic leucocyte count (DMLC) as standard, a total of 739 quarter milk samples were examined. The results obtained were as follows: 1. Of the 739 samples, 24.4% had positive DMLC value (over 500,000 leucocytes per mI.), 32.6% positive MCMT reaction, 34.9% positive RRT reaction and 39.9% positive MWT reaction. 2. The identical ratings of the three mastitis screening tests with DMLC values were 60.7% (MWT), 61. 8% (MCMT) and 72.1% (RRT). 3. The mean reaction values of the predicted mastitis screening tests were $1.09{\pm}0.01$ (MWT), $1.12{\pm}0.06$ (MCMT) and $1.25{\pm}0.40$ (RRT). The efficiency ratings of them were 34.8% (MWT), 49.3% (RRT) and 55.0% (MCMT) respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.97-104
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• 2001

Decomposition of trichloroethlyene(TCE) in electron beam irradiation was examined on order to obtain information on the treatment of VOC in air. Air containing vaporized TCE has been studied in a flow reactor with different reaction environments, at various initial TCE concentration and in the presence and absence of water vapor. Maximum decomposition was observed in oxygen reaction environment and the degree of decomposition was about 99% at 20kGy for 2,000ppm initial TCE. The concentration of TCE exponentially decreased with dose in air and pure oxygen. The effect of water vapor on TCE decomposition efficiency was examined. The decomposition rate of TCE in the presence of water vapor (5,600 ppm) was approximately 10% higher than that in the absence of water vapor. Dichloroacetic acid, dichloroacethyl chloride and dichloroethyl ester acid were identified as primary products of this reaction adn were decomposed and oxidized to yield CO and $CO_2$. Perchloroethylene, hexachloroethane, chloroform and carbon tetrachloride were also observed as highly chlorinat-ed by products.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.182-187
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• 2001

This paper examines the effects on human reaction time and mental fatigue of changes in the intensity of physical activity. A treadmill-equipped instrument and perception tester were used to attain several levels of physical activity. In this paper, in order to determine the individual levels of physical activity of subjects, Borg-RPE scale, Heart Rate(HR) and Respiratory Quotient(RQ) were used. Also, a reaction test in whole-body activity on treadmill-equipped instrument and an addition test as an indicator of mental fatigue were performed. In the above experiments, the scores obtained in addition test administered before and after Physical activity at each intensity level used. Restricted within the limits of this paper, the results of these tests showed that mental fatigue decreased after physical activity.

• YAKHAK HOEJI
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• v.39 no.1
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• pp.48-54
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• 1995

Coupling of tetracycline(Tc) to dithiocarbamate chitosan(DTCC) via chelate bond was investigated varying reaction time, concentration, temperature, pH, and Ca(II)/Tc ratio. The amount of Tc bound to matrix increased to give a maximum and decreased as the reaction proceeded. The degree and rate of dissociation of Tc complex were affected by the reaction temperature, and pH. By running the reaction at low temperature and pH, the degree of dissociation was greatly diminished. Properties of drug-release from DTCC-Ca(II)-Tc complex were studied by batch- and flow-method and release of Tc and CA(II) by flow method followed nearly zero-order. DTCC-Ca(II)-Tc showed very prolonged antimicrobial activity compared to that of free Tc.

• Bulletin of the Korean Chemical Society
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• v.21 no.12
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• pp.1233-1238
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• 2000

$Mo/{\gamma}-Al_2O_3catalysts$ modified with Fe, Co, and Ni were prepared by impregnation method and catalytic activity for water gas shift reaction was examined. The optimum amount of Mo loaded for the reaction was 10 wt% $MoO_3$ to ${\gamma}-Al_2O_3.$ The catalytic activity of $MoO_3/{\gamma}-Al_2O_3was$ increased by modifying with Fe, Co, and Ni in the order of Co${\thickapprox}$ Ni > Fe. The optimum amounts of Co and Ni added were 3 wt% based on CoO and NiO to 10 wt% $MoO_3/{\gamma}-Al_2O_3$, restectively. The TPR (temperature-programmed reduction) analysis revealed that the addition of Co and Ni enganced the reducibility of the catalysts. The results of both catalytic activity and TPR experiments strongly suggest that the redox property of the catalyst is an important factor in water gas shift reaction on the sulfided Mo catalysts, which could be an evidence of oxy-sulfide redox mechanism.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.189-195
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• 2007

The purpose of this study was to analyze the effects of shoes with curved out-sole on the pressure, reaction force(sum of pressure) on foot and relations between the rolling speeds and pronation of foot. The foot pressure, reaction force and pressure center on the foot surface of shoe were measured with NOVEL padar system, and 3 type shoes were used to compare the position and speed of pressure center and the foot reaction force, which were s(target) shoe with soft cushions in middle part of out-sole and curved out-sole, m shoes with two type- soft, hard, hardness out-sole and curved out-sole and n shoes with flat out-sole. The subjects were 13 female university students, had weared the 3 type shoes for 6 weeks on two-weeks shifts for adaptation before experiment and put on 3-type shoes repeatedly and randomly and walked on treadmill with 3.5km/h and 80 steps/min. The data were captured with 30Hz and readjusted with 5kgf threshold reaction force. The results can be summarized as follow. 1. There were no difference in maximum reaction force on initial contact period and total foot impact, but statistical difference in maximum reaction force on takeoff period : s, m, n in ascending order. 2. There were some difference in rolling speeds for support periods. At initial contact, the rolling speed of s shoes was fastest but at periods between first and second maximum reaction force, that of m shoes fastest. 3. There was a negative relation between rolling speeds and the length of lever arm on initial reaction force related to pronation. It seems shoes with various curved shapes and hardness could make effects on the rolling features and the rolling speed also have some relationships with walking efficiency, absortion of impact and pronation.

• Elastomers and Composites
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• v.12 no.1
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• pp.27-32
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• 1977

The kinetics of azo-coupling reaction of N-acetyl-H-acid (1-acetamino-8-hydroxynaphthalene-3, 6-disulfonic acid) with several heterocyclic diasonium compounds such as diazotiged 3-aminopyridine, 3-aminoquinoline, 8-aminoauinoline and aniline was studied. It was found that reactions proceeded at remarkably different rate. Reaction rate was in increasing order; 3-aminopyridine, 3-aminoquinoline, 8-aminoauinoline and aniline. And the activation energies were 9.62, 10.10, 10.39, 10.70 Kcal/mole, respectively. Especially, the rate constant of 3-aminopyridine was 100 times larger than that of benzene diasonium compound even in strong acidity. Hammett plot was also made of the rate constants obtained against the heterocyclic substituent constants reported in the literature. A good linear relationship was obtained and the reaction constant of N-acetyl H-acid was calculated to be 3.14.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.118-123
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• 1991

Potentially dangerous nitrosamines have been shown to result from the reaction of sodium nitrogusside with several drugs under physiological conditions (pH 7.3 and $37^\circ{C})$. In each case the products were identical to those produced upon reaction with nitrous acid at much lower pH values. Reaction rates were shown to reflect a first order dependence on both amine and nitroprusside concentrations and to increase at higher pH values, approximately in proportion to concentrations of unprotonated amine. Fast reactions of sodium nitroprusside with reduced glutathione, cysteine, and ascorbate suppress but do not prevent the conversion of amines into N-nitrosamines. These results show sodium nitroprusside to be very potent nitrosating agent under physiological conditions and suggested nitrosamines may be formed during its normal pharmacological administration.