• Proceedings of the KSME Conference
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.949-955
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• 2000

Numerical study with detailed chemistry has been conducted to investigate the NOx formation and structure in $CH_4/Air-CO_2$ counterflow diffusion flames. The importance of radiation effect is identified and the role of $CO_2$ addition is addressed to thermal and chemical reaction effects, which can be precisely specified through the introduction of an imaginary species. Also NO separation technique is utilized to distinguish the contribution of thermal and prompt NO formation mechanisms. The results are as follows : The radiation effect is dominant at low strain rates and it is intensified by $CO_2$ addition. Thermal effect mainly contributes to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. It is noted that flame structure is changed considerably due to the addition of $CO_2$ in such a manner that the path of methane oxidation prefers to take $CH_4 {\rightarrow}CH_3{\rightarrow}C_2H_6{\rightarrow}C_2H_5$ instead of $CH_4 {\rightarrow}CH_3{\rightarrow}CH_2{\rightarrow}CH$. At low strain rate(a=10) the reduction of thermal NO is dominant with respect to reduction rate, but that of prompt NO is dominant with respect to total amount.

• Korean Journal of Animal Reproduction
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• 제14권3호
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• pp.223-230
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• 1990

This experiment was carried out to investigate in vitro maturation rate of pig follicular oocytes cultured from 30 to 48hr in TCM 199 supplemented with gonadotropins(FSH, LH) and estradiol-17$\beta$ and in vitro fertilization with ejaculated sperm preincubated in BO medium containing 2mM caffein and development of IVF oocytes. The results obtained in this experiments were as follows ; 1. In addition of hormones, in vitro maturation rate of follicular oocyte increased gradually from 36hr and 74.47% at 48hr in addition of hormones, but there was no differences among in vitro maturation rates after 36hr of culture. 2. Penetration rate of pig oocytes matured in FSH＋LH＋E2 and FSH＋E2 was 71.8%, 71.0% and significantly increased by the addition of hormones. 3. Percentage of developed oocytes was 44.4% for oocytes matured in FSH＋LH＋E2-added medium and 48.7% for oocytes matured in FSH＋E2-added medium, respectively. 4. Two to 16 cells stage embryos were obtained only when pig oocytes matuerd in vitro in hormones-added medium and 72hr after IVF. 5. From present results, it is concluded that gonadotropins and estradiol17$\beta$ can enhance in vitro fertilization and subsequent development as well as in vitro maturation pig follicular oocytes.

• Journal of the Korean Chemical Society
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• 제36권2호
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• pp.287-292
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• 1992

The rate constants of the nucleophilic addition reaction of amines (piperidine and diethylamine) to phenylvinylketone in various solvents have been determined by UV spectrophotometry at $25^{\circ}C$. On the basis of the high sensitivity of the rate to the polarity of the medium, it may be concluded that the reaction intermediate has zwitterionic character. The effect of the solvents on the rate of the bimolecular nucleophilic addition reaction is described well by the Kirkwood equation: The transition state of the reaction has a cyclic structure formed through an intramolecular hydrogen bond. The addition reaction of primary and secondary amines to phenylvinylketone in all solvents take place considerably faster than that of tertiary amine and this results also can be explained by the intermediate products in the reaction have a cyclic structure formed through an intramolecular hydrogen bond for the primary and secondary amines but not for the tertiary amine.

• Journal of the Korean Ceramic Society
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• 제34권8호
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• pp.861-869
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• 1997

In order to investigate the reaction in the system of anhydrite II-blast furnace slag, the paste hydration which made up with a liquid/solid ratio of 0.45 for 1, 3, 7, 14, 28days by the addition of accelerators to 10~30wt.% slag with natural gypsum calcined for 1hour at 500/$700^{\circ}C$ was studied by combined water determination, XRD, DTA, DSC and SEM. As a result of this experiment, it was found that hydration rate was faster in the system calcined at 50$0^{\circ}C$. Therefore the anhydrite was converted to calcium sulfate dihydrate in the hydration for 1day but the slag was not almost reacted. For the gypsum calcined at $700^{\circ}C$, the hydraton rate in the system of K2SO4 addition was faster than others in the earier period, but the activated effect of the system of Al2(SO4)3 addition was regarded as the highest over 3days. As the amount of slag was increased, they dydration rate was delayed and ettringite was observed in the case of K2SO4 system. However both Al2(SO4)3 and AlK(SO4)2 systems showed calcium sulfate dhydrate only as hydrated products.

• Magazine of the Korean Society of Agricultural Engineers
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• 제42권2호
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• pp.93-98
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• 2000

This study is performed to evalute experimentally the nondestructive properties on the concrete that is treated with crushed oyster shell powder of 0.15m or smaller in diameter. The ultrsonic pulse velocity of crushed oyster shell concrete(COSC) is in the range of 4.110-4.267m/s, and the dynamic modulus of elasticity of COSC range from 288$\times$10$^3$ to 318 $\times$10$^3$kgf/$\textrm{cm}^2$. The ultrasonic pulse velocity and dynamic modulus of elasticity are similar to those of normal portland cement concrete. The highest ultrasonic pulse velocity and dynamic modulus of COSC are measured at the 2.5% addition rate by weight of crushed oyster shell powder. The acid-resistance in increased of the content of crushed oyster shell powder. The acid-resistance of COSC with 15% addition rate by weight of crushed oyster shell power is 1.6 times greater than that of normal portland cement concrete. It is concluded that the addition of crushed oyster shell powder to normal portland cement concrete contributed to improve the nondestructive properties of concrete.

• Journal of the Korean Chemical Society
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• 제33권1호
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• pp.127-134
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• 1989

The rate constants of the nucleophilic addition reaction of 3-mercaptopropionic acid to the ${\beta},\;{\beta}$-diethoxycarbonylstryene derivatives (H, p-OCH$_3$, 3,4,5-(OCH$_3)_3$, 3,4-methylenedioxy) were determined by ultraviolet spectrophotometry, and rate equation which could be applied over a wide pH range was obtained. On the basis of pH-rate profile and the presence of general base catalysis, a plausible mechanism of this addition reaction was propound:Below pH 6.0 the reaction was initiated by the addition of neutral 3-mercaptopropionic acid molecule, and in the range of pH 6.0∼8.0, a neutral 3-mercaptopropionic acid molecule and a sulfide anion competitively attacked to the double bond. Above pH 8.0, the reaction proceeded through the addition of a sulfide anion.

• Korean journal of food and cookery science
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• 제13권3호
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• pp.348-355
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• 1997

As a trial to expand the use of oligosaccharide, tomato jams were made with various kinds and addition rate levels of oligosaccharide and their quality characteristics were evaluated by instrumental analyses and sensory evaluation. As the addition rate of oligosaccharides increased, 1. the sweetness of tomato jams decreased compared to those of control containing sugar, 2. the lightness and yellowness were increased, however, the redness was decreased, 3. the hardness and adhesiveness of tomato jams containing liquid type oligosacchairdes were lower and those of powder type were higher than control. The springiness of the samples containing oligosaccharide was lower than that of control, however, there was no significant difference in cohesiveness. In sensory evaluation, tomato jams containing oligosaccharides were generally similar or better than control. Color, viscosity, flavor and overall acceptability of the samples containing powder type oligosaccharide were higher than those of liquid type. Tomato jams containing 15% powder type oligosaccharide and 35% sugar showed the highest overall acceptability.

• Journal of Magnetics
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• 제14권4호
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• pp.150-154
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• 2009

The effect of Ga and, Nb addition on the kinetics and mechanism of the disproportionation of a Nd-Fe-B alloy were investigated by isothermal thermopiezic analysis (TPA) using $Nd_{12.5}Fe_{(81.1-(x+y))}B_{6.4}Ga_xNb_y$ (x=0 and 0.3, y= 0 and 0.2) alloys. The addition of Ga and Nb retarded the disproportionation kinetics of the Nd-Fe-B alloy significantly, and increased the activation energy of the disproportionation reaction. The disproportionation kinetics of the $Nd_{12.5}Fe_{(81.1-(x+y))}B_{6.4}Ga_xNb_y$ alloys measured under an initial hydrogen pressure of 0.02 MPa were fitted to a parabolic rate law. This suggested that during the disproportionation of $Nd_{12.5}Fe_{(81.1-(x+y))}B_{6.4}Ga_xNb_y$ alloys with an initial hydrogen pressure of 0.02 MPa, a continuous disproportionation product is formed and the overall reaction rate is limited by the diffusion of hydrogen atoms (or ions).

• Journal of Korean Society of Transportation
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• 제10권2호
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• pp.5-24
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• 1992

This research presets the method of determining basic capacity of signalized intersection using the concept of ideal saturation flow rate. Vehicle discharge rates during green time were collected and studied as part of the preparation of Korean Highway Capacity Manual. From the result of this study the ideal saturation flow rate and saturation queue position were determined. In addition, based on the ideal saturation flow rate two geometric adjustment factors(lane width and grade adjustment factors) were studied. The results were presented in this paper.

• Journal of the Korean Society of Safety
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• 제16권4호
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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.