• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.230-230
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• 2017

About 200 rice varieties for irrigated and rainfed lowland ecosystems were released in the Philippines, which were bred for improving yield under favorable conditions. Root plasticity plays key roles in maintaining crop productivity under abiotic stressed conditions. We hypothesized that some of these varieties possess root plasticity traits in response to water stressed conditions. This study aimed to evaluate the root system development and dry matter production of 14 randomly selected rice varieties (6 irrigated lowland and 9 rainfed varieties) under progressive drought (PDR) and soil moisture fluctuations (SMF) stress conditions. Two experiments were done in rootbox and line source sprinkler systems (LSS). Each of the varieties was subjected to well-watered (WW), PDR and SMF conditions during vegetative stage in rootbox system while the same genotypes were subjected to different intensities of drought stress under LSS. Under rootbox system, PDR and SMF significantly reduced shoot dry matter production in all varieties relative to their WW controls. Among varieties, NSIC Rc238 (irrigated lowland) showed the least reduction in shoot dry weight (SDW) in both PDR (by 11.8%) and SMF (by 26.9%) conditions. Less reductions in SDW of NSICRc238 were partially attributed to the promotion of L-type lateral roots, thus increasing total lateral root length by 24.2% and 30.7% under PDR and SMF, respectively. In LSS, SDW of NSIC Rc238 under mild drought stress (16-21% soil moisture content (SMC) had 31.8% reduction relative to its WW control (${\geq}22%SMC$) and had lower sensitivity drought index. Compared with the IR64 susceptible check and NSIC Rc9 tolerant check, NSIC Rc238 had higher SDW by 90.8% and 38.6%, respectively. Furthermore, no rainfed lowland varieties included in the experiment performed well under different water stress treatments. The results implied that some other irrigated lowland rice varieties may also possess drought dehydration avoidance root plasticity traits under water-stressed growing environments.

• The Journal of Industrial Distribution & Business
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• v.11 no.3
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• pp.39-50
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• 2020

Purpose: Agriculture, which is heavily influenced by climate conditions, is one of the industries most affected by climate change. In this respect, various studies on the impact of climate change on the agricultural market have been conducted. Since climate change is a long-term phenomenon for more than a decade, long-term projections of agricultural prices as well as climate variables are needed to properly analyze the impact of climate change on the agricultural market. However, these long-term price projections are often major constraints on studies of climate changes. The purpose of this study is to analyze the impacts of climate changes on the Korean onion market using ex-post analysis approach in order to avoid the difficulties of long-term price projections. Research design, data and methodology: This study develops an annual dynamic partial equilibrium model of Korean onion market. The behavioral equations of the model were estimated by OLS based on the annual data from 1988 to 2018. The modelling system is first simulated to have actual onion market conditions from 2014 to 2018 as a baseline and then compared it to the scenario assuming the climatic conditions under RCP8.5 over the same period. Scenario analyses were simulated by both comparative static and dynamic approach to evaluate the differences between the two approaches. Results: According to the empirical results, if the climate conditions under RCP8.5 were applied from 2014 to 2018, the yield of onion would increase by about 4%, and the price of onion would decrease from 3.7% to 17.4%. In addition, the average price fluctuation rate over the five years under RCP8.5 climate conditions is 56%, which is more volatile than 46% under actual climate conditions. Empirical results also show that the price decreases have been alleviated in dynamic model compared with comparative static model. Conclusions: Empirical results show that climate change is expected to increase onion yields and reduce onion prices. Therefore, the appropriate countermeasures against climate change in Korean onion market should be found in the stabilization of supply and demand for price stabilization rather than technical aspects such as the development of new varieties to increase productivity.

• Computational Structural Engineering
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• v.5 no.4
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• pp.133-142
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• 1992

An analytical model was developed for predicting the pullout behavior of straight beam longitudinal bars anchored at exterior beam-column connections. The model incorporates a local bond constitutive simulation capable of considering the effects of anchored bar diameter, yield strength and the spacing, concrete compressive strength, and column pressure on the bond characteristics of deformed bars in confined conditions of exterior joints. The analytical techniques adopted in this study were shown to satisfactorily predict the results of pullout tests on straight bars embedded in confined concrete specimens. An evaluation of the ACI-ASCE Committee 352 development length requirements in exterior joint conditions was made using the developed analytical approach. The results of this analytical evaluation are indicative of the conservatism of the current development length requirements in the confined conditions of exterior joints.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.129-132
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• 2000

The main objectives of the study were to find optimum fermentation conditions of Propionibacterium acidipropionici for the production of organic acids. Three strains of Propionibacterium acidipropionici were selected for batch fermentation. Nutrients and environmental conditions on cell growth were defined by series of experiments. The optimum conditions of peptone, yeast extract, pH were determined to be 1.5%, 0.75%, $5.5{\sim}7.5$, respectively. Among the straines of P. acidipropionici selected for the experiment, ATCC4965 was the best in terms of total productivity and cell yield, which values were 0.29g total acids/L/h and 0.26 g dry cell/g glucose, respectively.

• Research in Plant Disease
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• v.9 no.3
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• pp.166-169
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• 2003

Occurrence of cercospora leaf spot by Cercospora capsici is assamed to remarkbly cause the yield reduction through the leaf spot, yellowing of leaves and early defoliation in pepper cultivation. To develop resistant cultivar, optimal screening conditions of pepper against cercospora leaf spot were studied. Optimal screening conditions were 3.4 ${\times}$ $10^5$ conidia/ml conidial suspension were sprayed on to the leaves of 30~40 days old pepper seedlings, incubated at 15~$20^{\circ}C$/20~$25^{\circ}C$(day/night) and examined 20 days after inoculation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.4
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• pp.378-386
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• 2017

Friction stir welding was performed using six welding conditions to evaluate the mechanical properties and microstructure of the welded zone based on its temperature change in the extruded plate of magnesium alloy AZ61. The welded zone temperature was measured using a thermocouple, and the maximum temperature ranges for the advancing and retreating sides were approximately $210-315^{\circ}C$ and $254-339^{\circ}C$, respectively. Depending on the welding conditions, a temperature difference of more than $100^{\circ}C$ was observed. In addition, the maximum yield strength and maximum tensile strength of the welded component was 84.4% and 96.9%, respectively, of those of the base material. For the temperatures exceeding $300^{\circ}C$, oxidation defects occurred in the weld zone, which decreased the mechanical strength of the weld zone. The microstructure and texture confirmed that fracture occurred because of the grain size deviation of the welding tool and the severe anisotropy of the texture of the welded joints.

• Microbiology and Biotechnology Letters
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• v.10 no.1
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• pp.45-52
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• 1982

A fungus with the highest protopectinase productivity was selected among 205 strains isolated from the soil and identified as a Verticillium sp. The Verticillium sp. was cultivated on wheat bran and the crude extruct of its culture medium showed the highest protopectinase activity on the following conditions: 3 days of cultivation time, 27$^{\circ}C$ of cultivation temperature, 1.2 $m\ell$/g wheat bran of water content, and reinforcement of ammonium nitrate and calcium chloride at the concentration of 0.5 and 0.02%, respectively. The optimum conditions for pectin production from Citrus peel pulp by the protopectinase were consequently obtained as follows: 20$m\ell$/g of liquid volume-to-pulp weight ratio, 4$0^{\circ}C$ of reaction temperature, and 4 of reaction pH. The higher the enzyme concentration, the better the yield of pectin and the shorter the reaction time. Total 45.6mg of pectin/g peel was produced by 1 hour reaction at the enzyme concentration of 10.5 units/$m\ell$. Molecular weight of the pectin produced by the enzyme was estimated to be about 62,000 by Smit and Bryant's method.

• Journal of Microbiology and Biotechnology
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• v.19 no.3
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• pp.299-306
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• 2009

Dissolved oxygen (DO) has a significant effect on the molecular weight of hyaluronic acid (HA) during the fermentation of Streptococcus zooepidemicus. Therefore, to further investigate the effect of DO on the yield and molecular weight of HA, this study compared the metabolic flux distribution of S. zooepidemicus under aerobic conditions at various DO levels. The metabolic flux analysis demonstrated that the HA synthesis pathway, considered a dependent network, was little affected by the DO level. In contrast, the fluxes of lactate and acetate were greatly influenced, and more ATP was generated concomitant with acetate at a high DO level. Furthermore, the has gene expression and HA synthase activity were both repressed under anaerobic conditions, yet not obviously affected under aerobic conditions at various DO levels. Therefore, it was concluded that the HA molecular weight would seem to depend on the concomitant effect of the generation of ATP and reactive oxygen species. It is expected that this work will contribute to a better understanding of the effect of the DO level on the mechanism of the elongation of HA chains.

• Analytical Science and Technology
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• v.5 no.4
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• pp.373-379
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• 1992

The pyrolysis conditions for the thermal isomerization products of pinane were carried out by the furnace type pyrolyzer and the curie-point pyrolyzer equipped with gas chromatograph and mass spectrometer. It was confirmed that curie-point type is much better furnace type, and high yield (70%) of citronellene was obtained from pinane as the main isomerization product under the best conditions by curie-point type. The optimum conditions of pyrolysis are $590^{\circ}C$ for 4 sec. and the major products were indentified as citronellene, m-Menth-6-ene, m-Menth-1-ene and 1-Methyl-4-(1-methylethylidiene) cyclohexane.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.406-412
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• 1998

Such extraction conditions as the kinds of solvent, extracting temperature, extracting time, ratio of material to solvent and particle size of material, were studied to maximize the extraction of oleoresin from chipi. Larger amount of soluble solids were extracted from seeds with nonpolar solvents (hexane, pentane, ether) for extraction, because the seeds contained large amount of crude fats and monoterpene(limonene) volatile compounds. Larger amount of soluble solids were extracted from peel with polar solvents(methanol, ethanol) of extraction because of large amount of water soluble colors, sugars and oxygenated terpene bolatile compounds in the peel. The application of the solvents in intermediate polarity (dichloromethane, acetone) resulted in more effective extraction of soluble solid and volatile compounds. Expecially, dichloromethane was an excellent solvent in extraction of volatile compounds. In the concern of volatile compound recovery yield, the optimum extraction conditions, such as temperature, time, mixing ratio of material to dichloromethane and mean particle size, were $25^{\circ}C$, 10min, 1:10(w/v), 355~250${\mu}{\textrm}{m}$ for chopi peels and 3$0^{\circ}C$, 10min, 1:8(w/v), 355~250${\mu}{\textrm}{m}$ for chopi seeds, respectively.