• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권9호
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• pp.467-475
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• 1999

This paper presents an analysis method of a forward converter, using both the finite element method considering the external circuit and a state variables equation. The converter operates at 50kHz and its one period is divided into two modes for the simplicity of the analysis. In the first mode, the switching transistor turns on and an input power is transferred into the load by the electromagnetic conversion action of a ferrite transformer. In the second mode, the switching transistor turns off and the stored energy in an inductor is delivered to the load, and the transformer core is demagnetized by the reset winding current. In this paper, time-stepping finite element method taking into account the on-state electrical circuit of the converter in used to analyze both the electrical circuit and electromagnetic field of the magnetic device during the first mode and the demagnetization period of the transformer core. Then a state variables equation for the circuit which the inductor current flows is constituted and solved during the second mode. As a result, the simulation results have been good agreement with the results obtained form experiment.

• 대한약리학회지
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• 제10권2호
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• pp.63-74
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• 1974

This study was carried out to observe the direct effect of hydrocortisone on renal function by infusing it into a renal artery. Hydrocortisone (5mg/kg) or saline (0.5 ml/kg) was infused directly into the left renal artery of the rabbit, the right kidney was left intact to serve as a control for general action of acetazolamide (10 mg/kg) or aminophylline (10 mg/kg), which was administered intravenously 30 minutes after the direct infusion of pretreated drugs (hydrocortisone or saline). The changes of urine volume, pH, urinary excretion rates of $Na^+,\;K^+\;and\;Cl^-$, and the clearances of inulin and PAH were measured at an interval of 10 minutes for half an hour after the direct infusion of hydrocortisone or saline, and for one hour after intravenous administration of acetazolamide or aminophylline. The results of the experiment were as follows: 1. Significant changes in urine volume and urinary electrolytes (excreted rates of $Na^+,\;K^+\;and\;Cl^-$) were observed in the hydrocortisone-infused group 10 minutes after the administration of acetazolamide, compared with the saline-infused group. Especially, the effect was more potent on the infused (left) side than on the contralateral (right) side. 2. Significant changes in urine volume and urinary electrolytes were also observed in all the aminophylline-treated groups, but no remarkable difference was noticed between the hydrocortisone-infused group and the saline-infused group, nor between the left and right sides. 3. No signicant changes in the clearances of inulin and PAH were in the infused (left) side of all the experimental groups, as compared with the contralateral (right) side. From the above results, it is obvious that hydrocortisone infused into a renal artery exerts diuretic action when administered in combination with acetazolamide, and the mechanism of action rests not on its hemodynamic change for renal blood flow, but on the potentiation of carbonic anhydrase inhibiting action. However, the exact mode of action remains yet to be clarified.

• Preventive Nutrition and Food Science
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• 제12권4호
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• pp.259-266
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• 2007

It has been proposed that the mode of action of nisin against vegetative cells and spores of Clostridium botulinum is different. However, clear explanation is not available. Therefore, nisin action against vegetative cells and spores of C. botulinum was investigated in this study. Nisin was added at various stages of spore-to-vegetative cell transition and changes to sensitivity to the bacteriocin were observed. Different nisin preparation (Nisaplin or pure nisin) was compared for their activity against different stages of spore transformation of C. botulinum ATCC 25763. Germination was measured by determining loss of heat resistance and observing phase darkening of spores under phase-contrast microscope. Nisin acted bactericidally against vegetative cells, but acted sporostatically against spores of C. botulinum under the same concentration. This bactericidal and sporostatic action of nisin was dependent on the concentration of nisin used. Presence of nisin during spore activation by heat increased subsequent phase darkening and germination rates. However, nisin inhibited the germination and the outgrowth, when it was added after heat activation stage. Findings from this study suggest that the time of addition of nisin is very important for the effective control of spores during the heating process of foods. In addition, it may be possible to apply nisin at the stage of processing that coincides with the most sensitive stage of spore transformation.

• 농약과학회지
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• 제2권3호
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• pp.1-20
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• 1998

Chlorsulfuron, one of sulfonylurea herbicides acts through inhibition of acetolactate syuthase (EC 4.1.3.18; ALS, also known as acetohydroxyacid synthase) in the branched-chain amino acid biosynthesis process. After chlorsulfuron-ALS interaction, many physiological and metabolic disruptions occur in plants. However, it is not clear how this chlorsulfuron-ALS interaction affects those physiological and metabolic processes and how this interaction leads subsequently to plant death. Several researchers suggested that the death of chlorsulfuron-treated plants might be due to a shortage of the branched-chain amino acids, an accumulation of toxic metabolites, and/or a depletion of photoassimilates. It remains as a mystery presently, however, if such changes result in the plant death. In this review, we discussed how the chlorsulfuran-ALS interaction leads to physiological and metabolic disruptions in plants.

• Journal of Photoscience
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• 제8권2호
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• pp.61-66
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• 2001

Using maize green- and white-leaf tissue, we have examined the effect of various chemicals on cytoplasmic leakage with respect to the light requirement or chloroplast targeting for their activities. Oxyfluorfen, oxadiazon, diuron, and paraquat, which are known as representative herbicides acting on plant chloroplasts, caused the electrolyte leakage only in the green tissues, whereas 2, 4-dinitrophenol, rose bengal (singlet oxygen producing chemical) and methyl-jasmoante (senscence-stimulating chemical) play a role both in green- and white-tissue. Benzoyl(a) pyrene, generating superoxide radical upon light illumination, functions only in white tissues. Tralkoxydim, metsulfuron-methyl and norflurazon showed no effect in two tested plant samples. In terms of light requirement in electrolyte leakage activity, diuron, oxyfluorfen, oxadiazon, rose bengal, and benzoyl(a) pyrene absolutely require the light for their functions, but other chemicals did not. based on these results, we could classify into four different response types according to whether chemicals require light or chlroplasts for their action. This classification is likely to be applied to simply and rapidly identify the requirement of light and chlroplasts for the actions of chemicals, thereby it makes easy to characterize many new herbicides that their action mechanisms are unclear, and to elucidate the mode of action of them.

• Journal of Ginseng Research
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• 제5권1호
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• pp.56-64
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• 1981

In order to evaluate the mode of action of ginseng saponin. metabolic changes in the plasma of normal and aloxan-intoxicated rats were compared Normal groups were administered only ginseng saponin 0, 5, 50mg/kg for 16 days, but alloxan-intoxicated groups were administered alloxan 25mg/kg for 3 days in addition to ginseng saponin. (1) No significant change in the concentration of glucose, cholesterol, and triglyceride (TG) was observed in normal rats but great inhibitory effect, except elevation of TG, was observed in alloxan-intoxicated rats. However, blood urea nitrogen was elevated in both normal and alloxan- intoxicated rats by administration of ginseng saponin 50mg/kg, and it was considered to be due to the impaired kidney function caused by overdose toxicity. (2) In normal rats, COT and ALP actIn,its were not changed by administration of ginseng saponin but GPT activity was decreased significantly. In alloxan-intoxicated rats, ginseng saponin exerted inhibitory action on the elevation of COT, CPT and ALP activity. But administration of ginseng saponin Smghg was much more effective than administration of 50mg/kg. (3) There fore, we concluded that ginseng saponin has the adaptogenic activity showing little effect on normal metabolism but great preventive action on alloxan-intoxicated rats.

• Steel and Composite Structures
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• 제10권4호
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• pp.297-315
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• 2010

This paper is concerned with free vibration characteristics and natural frequency of horizontally curved composite plate girder bridges. Three-dimensional finite element models are developed for the girders using the software package LUSAS and analyses carried out on the models. The validity of the finite element models is first established through comparison with the corresponding results published by other researchers. Studies are then carried out to investigate the effects of total number of girders, number of cross-frames and curvature on the free vibration response of horizontally curved composite plate girder bridges. The results confirm the fact that bending modes are always coupled with torsional modes for horizontally curved bridge girder systems. The results show that the first bending mode is influenced by composite action between the concrete deck and steel beam at low subtended angle but, on the girders with larger subtended angle at the centre of curvature such influence is non-existence. The increase in the number of girders results in higher natural frequency but at a decreasing rate. The in-plane modes viz. longitudinal and arching modes are significantly influenced by composite action and number of girders. If no composite action is taken into account the number of girders has no significant effect for the in-plane modes.

• Journal of Applied Biological Chemistry
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• 제59권4호
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• pp.281-284
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• 2016

To handle the development of antifungal drug resistance, the development of new structural modules and new modes of action for antifungals have been highlighted recently. Here, the antifungal activity of quinonemethidal triterpenoids such as celastrol, dihydrocelastrol, iguestein, pristimerin, and tingenone isolated from Tripterygium regelii were identified (MIC $0.269-19.0{\mu}M$). C. glabrata was the most susceptible to quinonemethide among the tested fungi. Furthermore, quinonemethide suppressed cyctochrome c peroxidase expression dramatically, decreasing fungal viability caused by the accumulation of hydrogen peroxide. Thus, cyctochrome c peroxidase downregulation of quinonemethide may be a key mode of action for antifungals.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.832-837
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• 1991

After many years of proliferation, the nuclear industry is indebted for a formidable consequence, the safe management of spent fuel. Naturally, the high radioactivity involved with such process motivates the development of effective telerobotic systems. Nevertheless, the existing master-slave type of tele manipulators are limited in effectiveness by the human operator's limited sensory and manipulation capabilities. This paper presents the result of a research effort to resolve such problems by assigning the slave manipulator a certain degree of intelligence; sensing and actuation. In the presented system, a perception-action loop is achieved using ultrasonic range sensor and laser distance sensor interfaced with the PUMA 760 industrial robot system, and applied to automating impact wrenching task for unbolting the lid of nuclear spent fuel cask. The perception-action loop performs determination of the cask location, collision avoidance and centering of the impact wrench onto the bolt head. To aid the insertion task and to provide versatility a mounting module consisting of an RCC device and an automatic tool changer is designed and implemented. The performance of the developed system is tested on the model cask and the result is given.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권4호
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• pp.185-193
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• 2002

With Increasing awareness towards environment-friendly and non-toxic pesticide azadirachtin obtained from neon tree (Azadirachta indica) is gaining more and more importance. Its broad-spectrum activity, Peculiar mode of action. eco-friendly and non-toxic action towards beneficial organisms has offered many advantages over chemical pesticides. All currently use commercial formulations based on azadirachtin contains azadirachtin extracted from seeds of naturally grown whole plants which is labour intensive process depending upon many uncontrollable geographical and climatic factors. Plant tissue culture can be a potential process for the pro-duction, offering consistent, stable and controlled supply of this bioactive compound, However the research on tissue culture aspects of production are in preliminary stage and requires culture and process optimization for the development of a commercially viable process. This review states the present status and future challenges of plant tissue culture for azadirachtin production.