• 한국동물위생학회지
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• 제30권3호
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• pp.291-304
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• 2007

Mutants of an obligate aerobic bacterium, Vitreoscilla, that have deficiency in heat-labile catalase-peroxidase hydroperoxidase I (HPI) were created by EMS treatment. The catalase-peroxidase HPI-deficient mutant showed substantially lower peroxidase activity in exponential and mid-stationary phase compared with the wild type strain. In late stationary phase, the mutant exhibited no peroxidase activity. Peroxidase deficiency in the mutant was revealed by polyacrylamide gels stained for peroxidase activity. Characteristically, catalase levels in the mutant increased about 14- and 8-fold during growth in the exponential and stationary phases, respectively, compared to those in the wild type, suggesting a compensatory effect for protection from $H_2O_2$ toxicity. The mutant showed differences in physiology from the wild type: retardation in growth rate and decrease in oxygen consumption. Both the wild type and the catalase-peroxidase HPI-deficient mutant of Vitreoscilla had lower growth rates in media containing increasing $H_2O_2$ concentrations. However, the mutant exhibited an additionally decreased growth rate after 6 to 8 h of growth compared to the wild type. The wild type was resistent up to 20 mM $H_2O_2$, whereas the mutant was very sensitive to high concentrations of exogenous $H_2O_2$. Although elevated catalase levels would provide protection of the bacteria from the deleterious effect of $H_2O_2$, it did not appear to be complete. Cell-free extracts of the mutant showed decreased NADH oxidation rates and higher accumulation of $H_2O_2$ during this oxidation. These results may account for the impaired growth and earlier onset of death phase by the catalase-peroxidase HPI-deficient mutant of Vitreoscilla.

• ALGAE
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• 제21권2호
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• pp.253-259
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• 2006

Organic substances are released from phytoplankton cells during all phases of growth. The type and amounts of organic substance excreted and the effects of nutrient limitation are often highly species-specific. Dinoflagellate, Cochlodinium polykrikoides grown in batch culture produced an exopolysaccharide. Exopolysaccharide and intracellular polysaccharide concentrations increased as C. polykrikoides cultures progressed from exponential phase, through stationary phase, to declining phase. In the exponential phase, the concentration of exopolysaccharide was relatively low, but in the stationary phase, it showed a rapid increase which seemed to coincide with the depletion of nitrate from the medium. Of the 20 amino acids analyzed, proline dominated in the organic matter of all cultures ranging from 48.2 to 79.9 nmol L–1, and constituting the 20-90% of total amino acids, and followed by histamine varying from 0.7 to 47.5 nmol L–1. Leucine and cysteine were also abundant in the stationary phase. The release rates of exopolysaccharide and intracellualr polysaccharide were higher the end of stationary phase than in the exponential phase. Exopolysaccharide concentration per cell was more than two times higher during the end of stationary phase than that in exponential phase. C. polykrikoides produced extracellular polysaccharide at a rate of 47.04 pg cell–1 day–1.

• 응용통계연구
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• 제34권4호
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• pp.611-622
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• 2021

본 논문에서는 변동성의 비대칭성과 비정상성을 동시에 고려하고 있다. 다양한 변동성 모형을 분석하고 있으며 모수적-붓스트랩을 통한 예측분포를 이용하여 변동성 모형의 예측 성능을 비교하고 있다. 오차항 분포로서 표준정규분포 및 표준화 t-분포를 고려하였으며 1-시차 후 예측과 2-시차 후 예측을 미국의 다우지수 사례를 통해 설명하였다.

• 대한기계학회논문집
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• 제18권4호
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• pp.826-834
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• 1994

The purpose of this study is to identify torque characteristics in capacitor type electric motors and to illustrate the effects of several design parameters on the fluctuating components of the motor torque. To do this, two revolving field theory and stationary reference frame theory were applied to derive governing equations for the torque generated by motor. For simulation studies, parameters of the motor components were measured under the conditions of no loading and locking. Based on these, effects of several design variables on the torque characteristics were analyzed and compared with the actual measurements, which were estimated indirectly by measuring the stator voltage and current. Then, some illustrative improvements in design are suggested by taking Taguchi method.

• 대한산업공학회지
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• 제32권2호
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• pp.133-140
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• 2006

Large signal type data sets are difficult to classify, especially if the data sets are non-stationary. In this paper, large signal type and non-stationary data sets are wavelet transformed so that distinct features of the data are extracted in wavelet domain rather than time domain. For the classification of the data, a few wavelet coefficients representing class properties are employed for statistical classification methods : Linear Discriminant Analysis, Quadratic Discriminant Analysis, Neural Network etc. The application of our wavelet-based feature selection method to a mass spectrometry data set for ovarian cancer diagnosis resulted in 100% classification accuracy.

• East Asian mathematical journal
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• 제13권1호
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• pp.23-32
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• 1997

• 전기저널
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• 1호통권121호
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• pp.14-18
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• 1987

• Bulletin of the Korean Chemical Society
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• 제16권8호
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• pp.764-768
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• 1995

• Journal of Biosystems Engineering
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• 제34권3호
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• pp.167-174
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• 2009

This study was conducted to develop an agaricus bisporus washing machine which uses compressed air to remove foreign materials attached on the surface of agaricus bisporus. A prototype of the washing machine was constructed, and performance of removing foreign materials was tested. Research results are as follows: 1. Several transferring methods including PE roller rotation, brush roller rotation, PE screw rotation, vibration plate, and belt conveyor were evaluated. Roller, screw, and vibration methods caused damages on the surface of the products, but belt conveyor method caused the least damages. 2. For air jet, a stationary nozzle type and a rotational type were evaluated. The best air jet nozzle was the jet-type nozzle, and the rotational type was more effective than stationary type nozzle. 3. With the conveyer belt, box type moving method and the rotational air jet nozzle, the washing machine showed the best performance when higher than 5.4${\times}$105 Pa of air jet pressure and lower than 0.047 m/s of moving speed was used. Working performance of the system was 650 kg/h, and the damaging rate was 1.2 %.

• 대한기계학회논문집B
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• 제30권9호
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• pp.873-881
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• 2006

The present study investigates the pressure drop characteristics in rotating two-pass ducts. The duct has an aspect ratio (W/H) of 0.5 and a hydraulic diameter $(D_h)$ of 26.67mm. Rib turbulators are attached crossly in the four different arrangements on the leading and trailing surfaces of the test ducts. The ribs have a rectangular cross section of $2mm(e){\times}3mm(w)$ and an attack angle of $70^{\circ}C$. The pitch-to-rib height ratio (pie) is 7.5, and the rib height-to-hydraulic diameter ratio $(e/D_h)$ is 0.075. The results show that the highest pressure drop among each region appears in the turning region for the stationary case, but appears in the upstream region of the second pass for the rotating case. Effects of cross rib arrangements are almost the same in the first pass for the stationary and rotating cases. In the second pass, however, heat transfer and pressure drop are high for the cases with cross NN or PP type ribs in the stationary ducts. In the rotating ducts, they are high for the cases with cross NP or PP type ribs.