• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.283-287
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• 2005

The slow evolution of global magnetic fields and other dynamical processes in atmospheres of CP magnetic stars lead to the development of induced electric currents in all conductive atmospheric layers. The Lorentz force, which results from the interaction between a magnetic field and the induced currents, may modify the atmospheric structure and provide insight into the formation and evolution of stellar magnetic fields. This modification of the pressure-temperature structure influences the formation of absorption spectral features producing characteristic rotational variability of some spectral lines, especially the Balmer lines (Valyavin et al., 2004 and references therein). In order to study these theoretical predictions we began systematic spectroscopic survey of Balmer line variability in spectra of brightest CP magnetic stars. Here we present the first results of the program. A0p star $\Theta$ Aur revealed significant variability of the Balmer profiles during the star's rotation. Character of this variablity corresponds to that classified by Kroll (1989) as a result of an impact of significant Lorentz force. From the obtained data we estimate that amplitudes of the variation at H$\alpha$, H$\beta$, H$\gamma$ and H$\delta$ profiles reach up to $2.4\%$during full rotation cycle of the star. Using computation of our model atmospheres (Valyavin et al., 2004) we interpret these data within the framework of the simplest model of the evolution of global magnetic fields in chemically peculiar stars. Assuming that the field is represented by a dipole, we estimate the characteristic e.m.f. induced by the field decay electric current (and the Lorentz force as the result) on the order of $E {\~} 10^{-11}$ cgs units, which may indicate very fast (< < $10^{10}$ years) evolution rate of the field. This result strongly contradicts the theoretical point of view that global stellar magnetic fields of CP stars are fossil and their the characteristic decay time of about $10^{10}$ yr. Alternatively, we briefly discuss concurring effects (like the ambipolar diffusion) which may also lead to significant atmospheric currents producing the observable Lorentz force.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.9 s.240
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• pp.1022-1031
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• 2005

Temporal behavior of the laser induced incandescence (LII) signal is often used for soot particle sizing, which is possible because the cooling behavior of a laser heated particle is dependent on the particle size. In present study, LII signals of soot particles are modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. The objective of this study is to obtain an appropriate calibration curve for determining primary particle size by comparing the gated signal ratio and double-exponential curve fitting methods. Not only the effects of laser fluence and gas temperature on the cooling behavior but also heat transfer mechanisms of heated soot particle have been investigated. The second-order exponential curve fitting showed better agreements with the LII signals than the gated signal ratio method which was based on the lust-order exponential curve fit. And the temporal decay rate of the LII signal and primary particle size showed nearly linear relationship, which was little dependent on the laser fluence. And it also could be reconfirmed that vaporization was dominant process of heat loss during first loons after laser pulse, then heat conduction played most important role while thermal radiation had little influence all the time.

• The Korean Journal of Physiology
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• v.7 no.1
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• pp.23-31
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• 1973

Numerous factors concern with the absorption of substances through the membrane of the gastrointestinal tract. To simplify the experimental condition, present work has been restricted to observe the disappearance rate of substance from the intestinal loop which was made in the jejunum, 70 cm apart from the pylorus of the adult rabbit. The purpose of the study is to clarify the absorption of urea through the jejunal wall is solely attributable to the concentration difference between the luminal fluid and plasma, and to observe the effect of adding red pepper upon the rate of absorption. The rabbits were anesthetized with nembutal, 35mg/kg I.V. Jejunal loop was made by ligating at 2 spots, 70 cm and 80cm apart from the pylorus. After rinsing with normal saline solution through the polyethylene tubing inserted from the end of the loop, 8 ml of test solution was placed through the same tubing. The test solution contained 200 mg% of urea and 150mg% of polyethylene glycol(M.W. 4,000) in normal saline solution. Right after placing the test solution the first specimen was taken through the tubing, and successive samplings were performed at 5, 10, 20, and 30 minutes. Logarithm of the difference of urea concentration between the luminal fluid and plasma was plotted against time elapsed after the onset of the experiment. If straight line is revealed, it would verify the nature of transport mechanism as diffusion, obeying the Fick's principle. The concentration of polyethylene glycol (PEG) was also measured in order to examine the change in the volume. PEG was used as the marker substance because it is not absorbable in the intestinal tract. Consequently the concentration of PEG relates inversely to the volume of the loop. Instantaneous concentration of urea in the loop times the volume will give the amount of urea remaining in the luminal fluid. The change in the amount of any substance is directly relate to the volume of the compartment and differs from the change in the concentration which is independent of the volume. After completion of the experiment without red pepper, it was added in the test solution and was centrifuged after thorough mixing. Supernatant of the mixture was placed in the loop and similar sampling were performed with the same time intervals that of previous run in order to observe the effects of the red pepper on the passive transport of the water soluble small substance, urea. The results obtained were as follows: 1. Logarithm of the concentration difference of urea between the luminal fluid and plasma was diminished exponentially as time elapsed. The decay constant in the experiment without red pepper was 0.0563/min. By adding red pepper in the test solution as much as the concentration rose to 4,000 mg% and 8,000 mg%, the decay constants were lowered to 0.0493/min and to 0.0506/min, respectively. The time interval by which the concentration difference dropped to one half of the initial value was prolonged. Without red pepper the half concentration time was 13.30 minutes, and by adding extract of red pepper, 15.31 minutes and 15.71 minutes were revealed. 2. The profile of the diminishing rate of tile amount of urea was quite different from that of the concentration because of the change in the volume of the loop during the observed period. 3. By adding the extract of red pepper, it slowed down the rate of absorption of urea in the intestinal loop, suggesting an increase in the diffusional barrier. 4. Larger dosage of red pepper brought an increase in the secretion of intestinal fluid with concomitant expansion of the luminal volume, and the retardation of the absorption of urea was noticed. This effect was largely dependent on the sensitivity of the individual animal to the red pepper, extract. The amount of urea remained after 10 minutes interval was 55.5% of the initial amount in the experiment without red pepper. On the other hand it was not consistent after administration of red pepper, showing 50.6% and 66.5% of the initial figures by adding 400 mg and 800 mg of red pepper in the test solution, respectively. It was postulated that symptom of diarrhea often encountered by taking a hot (red pepper) food might be attributable to the increase of secretion and the retardation of absorption in the intestinal tract.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.3
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• pp.128-134
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• 2016

An analysis of the main factors and its degree of impact on power production is performed against the landfill gas power plant in S landfill site. The number of normal operation (50 MWh & 24 hr) days was 70.9% to the total number of operation days from 2007 to 2014, and the percentage of the actual power production was 79.3% of 3,428,400 MW which is the theoretical maximum estimation. The ratio of factors that accounted for the efficiency of power production are: 44.0% of repairing of the defect and regular servicing, 37.4% of cut-down operation due to hydrogen sulfide, and 18.6% of air pre-heater washing, respectively. Yet, considering that the cut-down operation due to hydrogen sulfide was carried out for only two years, the high concentration of hydrogen sulfide was the most influential factors on landfill gas power production. The long-term power production was analyzed as 35.9 MWh in 2018, and the constant drop is anticipated, resulting in 16.6 MWh by 2028, and under 8.4 MWh in 2038.

• Journal of Korean Society of Forest Science
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• v.80 no.3
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• pp.303-310
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• 1991

Seasonal patterns of decomposition and nutrient release from the needle litter were examined using litter-bags in coastal Pinus thunbergii forests in nothern Kyushu, Japan. Dry matter losses from decomposing needle litter were smillar in all standsover a experimental period. Mass loss in dry weight is lost rapidly during the first year, and thereafter the rate of loss slows. Litter lost approximately 40% of initial mass in 1 yr. The predicted decay constant, k values ranged from 0.5 to 0.6 Decomposition half-times($t_{0.50}$) ranged from 1.1 to 1.4 year. In the decomposing needle litter, the concentrations of N and P generally increased with time while the concentration of K decreased. A decrease in absolute amount was noted for K during decomposition while in an increase was found for N. The order of mobility of elements was K>P>N. Mineralization phase of N had not appeared during the experiment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6B
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• pp.399-406
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• 2012

The objective of this research is to develop greenhouse gas generation models and estimation method of their parameters for solid waste landfills. Two models obtained by differentiating the Modified Gompertz and Logistic models were employed to evaluate two parameters of a first-order decay model, methane generation potential ($L_0$) and methane generation rate constant (k). The parameters were determined by the statistical comparison of predicted gas generation rate data using the two models and actual landfill gas collection data. The values of r-square obtained from regression analysis between two data showed that one model by differentiating the Modified Gompetz was 0.92 and the other model by differentiating the Logistic was 0.94. From this result, the estimation methods showed that $L_0$ and k values can be determined by regression analysis if landfill gas collection data are available. Also, new models based on two models obtained by differentiating the Modified Gompertz and Logistic models were developed to predict greenhouse gas generation from solid waste landfills that actual landfill generation data could not be available. They showed better prediction than LandGEM model. Frequency distribution of the ratio of Qcs (LFG collection system) to Q (prediction value) was used to evaluate the accuracy of the models. The new models showed higher accuracy than LandGEM model. Thus, it is concluded that the models developed in this research are suitable for the prediction of greenhouse gas generation from solid waste landfills.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.460-465
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• 2007

Endosulfan-${\alpha}$ endosulfan-${\beta}$ and endosulfan-sulfate, which are classified as pesticides, were degraded by use of UV energy and ultrasonic irradiation. The degradation residuals were analysed by gas chromatography with an electron capture detector and TOC (total oragnic carbon) analysis. The reactions were conducted in a quartz annular reactor equipped with a low pressure mercury multilamp (8Wx2) and a sonic generator. All the aqueous solutions were concentrated as 10 mg/L initially. Endosulfans were degraded each to result in 48.2% (${\alpha}$), 50.0% (${\beta}$) and 76.5% (sulfate) of removal efficiency by UV energy, and 66.9% (${\alpha}$), 55.8% (${\beta}$) and 72.7% (sulfate) by ultrasonic irradiation, respectively. In contrast to the results of the single-component solutions, degradation of the endosulfan-sulfate was greatly suppressed to result in the lowest degradation rate and removal efficiency in the three-component solutions. This finding suggests that there should be a reversible reaction with a substantially low equilibrium constant between endosulfan-${\alpha}$ or -${\beta}$ and -sulfate in the coexistence of the three endosulfans. TOC data showed the endosulfans were decomposed by 20%~40% toward complete mineralization, producing a quantity of intermediates induced by the radical reactions. We found that all the decay reactions considered in this study nicely fell into pseudo first-order rate.

• Journal of the Korean Chemical Society
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• v.39 no.4
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• pp.237-243
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• 1995

The measurments of neutral semiquinone radicals, which were formed from the laser flash photolysis of anthraquinone (AQ) in the mixed solvents were carried out by the time resolved electron spin resonance (trESR) spectroscopy. The chemically induced dynamic electron polarization (CIDEP) spectra of the neutral semiquinone radical (AQH${\cdot}$) and semiquinone radical anion (AQ${\cdot}$-) were successively detected in the laser flash photolysis of AQ in the mixtures of 2-propanol (PrOH) and triethylamine (TEA). The neutral semiquinone radical was short-lived with the half-life of 0.8 ${\mu}sec$, whereas the semiquinone radical anion was relatively stable and then its cwESR could be observed. The rate constant of the spin-depolarization of semiquinone radical anion was $2.6{\times}10^5 sec^{-1}$ and the decay of the radical anion was the first order reaction with the rate constant of $3.0{\times}10^2\; sec^{-1}$. No CIDEP of semiquinone radical anion was observed in the mixture of PrOH and the lower concentration of TEA than 2 percent. The CIDEP spectrum of the neutral semiquinone radical was detected in the mixture of benzene and TEA with the half-life of 3.0 ${\mu}sec$. The neutral semiquinone radical could not be detected by cwESR. Neither CIDEP nor ESR absorption could be observed in PrOH, TEA or benzene only.

• Korean Journal of Environmental Agriculture
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• v.34 no.2
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• pp.120-127
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• 2015

BACKGROUND: Supervised residue trials were conducted to establish pre-harvest residue limit(PHRL), a criterion to ensure the safety of the pesticide residue in the crop harvest, of amisulbrom for winter-grown cabbage in two fields. Following to application of amisulbrom on the crop, time-course study was carried out to obtain the amisulbrom dissipation of statistical significance which enabled to calculate the predicted values of PHRL. METHOD AND RESULTS: During cultivation under greenhouse condition, samples of winter-grown cabbage were collected at 0, 1, 3, 5, 7 and 10 days after amisulbrom application, and subjected to residue analysis. Analytical method was validated by recoveries ranging 93.7~100.0% as well as limit of quantitation(LOQ) of 0.04 mg/kg. Amisulbrom residues in winter-grown cabbage gradually decreased as time elapsed. The dissipation rate of the residue would be affected by intrinsic degradation along with dilution by the cabbage growth. The decay pattern was well fitted by the simple first-order kinetics. CONCLUSION: Biological half-lives of amisulbrom in winter-grown cabbage ranged 3.7~4.1 days in two field conditions. Based on the regression of amisulbrom dissipation, PHRLs of amisulbrom in winter-grown cabbage were recommended as 8.86~9.47 and 4.21~4.35 mg/kg for 10 and 5 days before harvest, respectively.

• Horticultural Science & Technology
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• v.34 no.4
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• pp.644-654
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• 2016

Supervised residue trials for mandipropamid in Korean cabbage(Brassica campestris L.) were conducted to establish its pre-harvest residue limit (PHRL), a criterion to ensure the safety of the terminal pesticide residue during cabbage production. Tissues of Korean cabbage were collected at 0, 1, 3, 5, 7, and 10 days after mandipropamid application and subjected to residue analysis. The analytical method was validated by recoveries ranging from 88.2-92.2% at two levels (0.4 and $2.0mg{\cdot}kg^{-1}$), and a limit of quantitation (LOQ) of $0.04mg{\cdot}kg^{-1}$. Mandipropamid residues in Korean cabbage gradually decreased over time. The dissipation rate of the residue would be affected by intrinsic degradation of the compound along with dilution resulting from the fast growth of Korean cabbage. The decay pattern was well fitted by simple first-order kinetics. Biological half-lives of mandipropamid in Korean cabbage ranged from 3.9-4.0 days in two field conditions. Calculated by the regression curve of mandipropamid dissipation, the PHRLs of mandipropamid in Korean cabbage were recommended as 11.07-12.19 and $5.76-6.05mg{\cdot}kg^{-1}$ for 10 and 5 days prior to harvest, respectively.