• 한국생태학회:학술대회논문집
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• 2002.08a
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• pp.83-91
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• 2002

The Red Queen hypothesis for the advantage of sex predicts that pathogens will evolve by increasing fitness with frequent encounters with specific host genotypes. In this study, BMV population size, measured as an indicator of fitness, was investigated during repeated passages through the same, or different host genotypes of the crop host, Hordeum vulgare (barley). Overall, mean BMV concentration within individual hosts was significantly higher in genetically homogeneous compared to heterogeneous host passage lines. In addition, BMV populations, passaged through a specific host variety, showed higher growth in that host variety compared to BMV passaged through varying varieties. These results supports the Red Queen hypothesis. However, the decrease in viral populations during passages contradicts the Red Queen. Nevertheless, the results found here show that even under simplified conditions, pathogens do not evolve in simple, predictable ways. Constraints on pathogen evolution may lead to counterintuitive results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.3 s.258
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• pp.373-379
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• 2007

In this study, we observe the application of shape memory alloy(SMA) into smart structures for repeatable actuation, because SMA changes its material properties and characteristics progressively under cyclic loading conditions and finally reaches stable path(state) after a certain number of stress/temperature loading-unloading cycles, so called 'training'. In this paper, SMA wires that have been in a stable state through the training are used. Stress-strain curve of the SMA wire at different temperature levels are measured. In addition, we observe other important effects such as the rate effect according to strain rates for rapid actuation response. The current work presents the experimental test using SMA wire after training completion by mechanical cycling. Through these tests, we measure the characteristics of SMA. With the estimated SMA properties and effects, we compare the experimental results with the simulation results based on the SMA constitutive equations.

• Mycobiology
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• v.29 no.1
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• pp.43-47
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• 2001

Genetic diversity of 21 Korean Phytophthora capsici isolates was analyzed by using several molecular markers such as random amplified polymorphic DNA(RAPD), M-13, microsatellite and random amplified microsatellite sequences(RAMS). The overall average similarity coefficient among the isolates was 86% based on the combined data obtained by the molecular markers. No molecular markers were found to be associated with hosts or geographic regions. In addition to RAPD, analysis based on repeated sequences such as $(GTG)_5$, M-13 and RAMS could be used to assess population structure of P. capsici.

• Toxicological Research
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• v.19 no.4
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• pp.311-314
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• 2003

This study was performed to investigate the effects of glycine on the development of tolerance to and physical dependence on morphine. Repeated administration of morphine (10 mg/kg) developed tolerance and physical dependence. Glycine (100, 200 and 400 mg/kg) was administered intraperitoneally (i.p.) to mice for 7 days prior to the morphine injection. Analgesic effects were estimated by the tail flick methods. The inhibitory degree of the development of morphine-induced analgsic tolerance by i.p. administration of glycine was evidenced by the increase in analgesic response to morphine. Glycine inhibited the development of tolerance to morphine. In addition, we separately measured jumping response as the naloxone-precipitated withdrawal sign in mice that had received the same morphine. Glycine reduced the number of jumping behaviors in morphine dependent mice. These results suggest that glycine might be useful the prevention or treatment of morphine tolerance and physical dependence.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.171-174
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• 2005

Suspected carcinogen, TCE and PCE, are the most common groundwater pollutants extensively used as a solvent and degreaser. In this study, oxygenases were immobilized in Ca-alginate and chitosan bead. TCE degradation by the immoblized enzyme beads were measured for various size, enzyme addition volume and TCE contact time. The degradation was decreased as increasing the bead size. For overnight , more than 20% of TCE was degraded. The variation of enzyme activity was tested for the repeated use of enzyme beads.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.649-656
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• 2008

Springback is one of factors affecting precision in metal forming. Its effect is particularly prominent in bending process. In this study, bending and forging process are used in order to manufacture a micro spring with two bending region from $60{\mu}m$ diameter wire. Springback in the process lowers the precision of the micro spring. Overbending for springback compensation has wide usage in a general way. However, this method requires repeated modifications of press dies until the tolerance is allowable, which causes that production cost and time increase. In this paper, we analyzed the mechanism of springback in the forming process of the micro spring using finite element method. In addition, a simple method to control springback without modifying dies was proposed by performing numerical analysis with various parameters.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2003.04a
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• pp.180-187
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• 2003

The lignin-degrading fungus Trichophyton sp. LKY-7 was immobilized in ca-alginate beads for laccase production and PCP remediation. The immobilized Trichopphyton sp. LKY-7 enabled the repeated use of this fungus for laccase production and produced high amount of laccase throughout 5 cycles incubation. As a laccase inducer oak wood meal(Quercus variabilis) seemed to be effective laccase inducer for Trichophyton sp. LKY-7, and the optimum addition amount was 1%(W/W) in glucose-peptone medium. Biotransformation of pentachlorophenol by immobilized Trichophyton sp. LKY-7 reached an efficency of up to 90% without toxic inhibition. Immobilized Trichophyton sp. LKY-7 might thus be applicable for semicontinuous laccase production and bioremediation to serve inoculum for reactor system.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.326-330
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• 2009

In this study, coarse-grained geomaterials were mixed with cementing binder. To do that, typical soils from road construction sites were selected to assess the strength and stiffness characteristics of cemented geomaterials mixed with cement and recycled fly ash. Mechanistic evaluation on these samples was performed depending on the various binder contents. Increasing cementing content tend to increase the resilient modulus under repeated loadings and unconfined strength respectively. In addition, the toughness of cemented geomaterials was also estimated in order to check the ability to resisting fatigue failure.

• Proceedings of the Safety Management and Science Conference
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• 2012.04a
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• pp.293-300
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• 2012

Reliability measures of questionnaire and ${\chi}^2$ contingency tests of categorized responses are most practical tools to analyze the characteristics of subjects of survey study. This research evaluates the Cronbaha's reliability measures by using Repeated Measure Design (RMD) with illustrated MINITAB examples. In addition, ${\chi}^2$ statistics of each cell of categorized tables can be effectively interpreted with the symmetric plot of correspondence analysis. The practical example is also discussed to provide comprehensive understanding of topic.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.299-303
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• 2011

This paper proposes a novel sensorless maximum power point tracking (11PPT) algorithm for PV systems. The method is based on dividing the operating time into several intervals in which the PV terminals are short circuited in one interval and the calculated short-current of the PV is obtained and used to determine the optimum operating point where the maximum output power can be obtained. The proposed MPPT algorithm has been introduced into a current-controlled boost converter whose duty ratio is controlled to the maintain MPP condition. The same sequence is then repeated regularly capturing the PV maximum power. The main advantage of this method is eliminating the current sensor. Meanwhile, this MPPT algorithm reduces the power oscillations around the peak power point which occurs with perturbation and observation algorithms. In addition, the total cost will decrease by removing the current sensor from the PV side. Finally, simulation results confirm the accuracy of the proposed method.