• Economic and Environmental Geology
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• v.41 no.6
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• pp.685-693
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• 2008

The rates of oxidative degradation of perchloroethene (PCE) and trichloroethene (TCE) using $KMnO_4$ solution were evaluated under the flow condition using a bench-scale transport experimental setup. Parameters which are considered to affect the reaction rates tested in this study were the contact time (or retention time), and the concentration of oxidizing agent. A glass column packed with coarse sand was used for simulating the aquifer condition. Contact time between reactants was controlled by changing the flow rate of the solution through the column. The inflow concentrations of PCE and TCE were controlled constant within the range of $0.11{\sim}0.21\;mM$ and $1.3{\sim}1.5\;mM$, respectively. And the contact time was $14{\sim}125$ min for PCE and $15{\sim}36$ min for TCE. The $KMnO_4$ concentration was controlled constant during experiment in the range of $0.6{\sim}2.5\;mM$. It was found that the reduction of PCE and TCE concentrations were inversely proportional to the contact time. The exact reaction order for the PCE and TCE degradation reaction could not be determined under the experimental condition used in this study. However, the estimated reaction rate constants assuming pseudo-1st order reaction agree with those reported based on batch studies. TCE degradation rate was proportional to $KMnO_4$ concentration. This was considered to be the result of using high inflow concentrations of reactant, which might be the case at the vicinity of the source zones in aquifer. The results of this study, performed using a dynamic flow system, are expected to provide useful information for designing and implementing a field scale oxidative removal process for PCE/TCE-contaminated sites.

• Research in Plant Disease
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• v.15 no.3
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• pp.187-192
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• 2009

Pepper powdery mildew, Leveillula taurica is one of the most important pathogens of pepper in the greenhouses and fields in Korea and is becoming a worldwide disease. These experiments were carried out to investigate the optimal germination, disease development conditions, disease incidence and effective inoculation methods of pepper powdery mildew. The incidence of powdery mildew was investigated throughout the country based on the major pepper growing areas in 2009. The average rate of infected leaves ranged from 15.3% to 81.8% in greenhouses and fields. Powdery mildew incidences were more severe in greenhouses than those of fields. The optimal temperature for conidial germination was $25^{\circ}C$ and showed the highest germination at 6 hs after treatment. The range of temperature for germination was $10^{\circ}C$ to $35^{\circ}C$. Temperature of greater than $30^{\circ}C$ and below $20^{\circ}C$ affected the abnormal germination and germ tube elongation. The optimal relative humidity for germination and germ tube elongation was 85% and germination increased as relative humidity increased. Disease development started 8 days after inoculation and showed the highest disease severity at 15 days in greenhouse and field regardless of varieties. Among three different inoculation methods tested the spore dropping method was better than touching with infected leaves and spraying with spore suspension. However, the method has limitation in mass inoculation due to the amount of time consumed.

• Korean Journal of Remote Sensing
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• v.33 no.5_3
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• pp.855-866
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• 2017

Several research cases using remote sensing methods to analyze changes of storage and dynamics of groundwater aquifer were reviewed in this paper. The status of groundwater storage, in an area with regional scale, could be qualitatively inferred from geological feature, surface water altimetry and topography, distribution of vegetation, and difference between precipitation and evapotranspiration. These qualitative indicators could be measured by geological lineament analysis, airborne magnetic survey, DEM analysis, LAI and NDVI calculation, and surface energy balance modeling. It is certain that GRACE and InSAR have received remarkable attentions as direct utilization from satellite data for quantification of groundwater storage and dynamics. GRACE, composed of twin satellites having acceleration sensors, could detect global or regional microgravity changes and transform them into mass changes of water on surface and inside of the Earth. Numerous studies in terms of groundwater storage using GRACE sensor data were performed with several merits such that (1) there is no requirement of sensor data, (2) auxiliary data for quantification of groundwater can be entirely obtained from another satellite sensors, and (3) algorithms for processing measured data have continuously progressed from designated data management center. The limitations of GRACE for groundwater storage measurement could be defined as follows: (1) In an area with small scale, mass change quantification of groundwater might be inaccurate due to detection limit of the acceleration sensor, and (2) the results would be overestimated in case of combination between sensor and field survey data. InSAR can quantify the dynamic characteristics of aquifer by measuring vertical micro displacement, using linear proportional relation between groundwater head and vertical surface movement. However, InSAR data might now constrain their application to arid or semi-arid area whose land cover appear to be simple, and are hard to apply to the area with the anticipation of loss of coherence with surface. Development of GRACE and InSAR sensor data preprocessing algorithms optimized to topography, geology, and natural conditions of Korea should be prioritized to regionally quantify the mass change and dynamics of the groundwater resources of Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.16-26
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• 2000

Physical characteristics and nutrient distributions in seawater were investigated to understand the mechanism of red tide outbreak in coastal waters off Kohung area. To identify any physical and chemical differences before, during and after the red tide outbreaks, 6 times of field observations have been carried out from May to October, 1997. We found that major environmental properties of the seawater in the study area were determined not by the local meteoric conditions or nearby-land influences, but by the intrusion of seawater from offshore. In particular, extreme environmental variations in seawater were found during the period of red tide outbreak from August to September. Before the red tide outbreak, high concentrations of DIN(Dissolved Inorganic Nitrogen)were found in seawater, but they decreased during the outbreak. Whereas no significant variations of DIP(Dissolved Inorganic Phosphate) were found. For the water mass in the semienclosed northern part of the study area, local nutrient sources originated from nearby-lands were estimated to cover 70% of total DIN input, but the rest part of the water mass in the study area, sporadic intrusion of offshore water mass could account for the major source of DIN supply. An offshore water mass influenced by Yangtze river effluent was suggested as one of the candidates with its high nitrate contents, high seawater temperature and low salinity. A red tide related phytoplankton, Gyrodinium impudicum, was found in seawater on the 21th day of August and, on the same day, a unique water mass with high temperature and extremely low salinity suddenly appeared in the study area. On the 22th day of September, after one and half month duration of red tide we found that red tide had disappeared simultaneously with the intrusion of new water mass with different characteristics.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.294-307
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• 2011

This experiment carried out to confirm characteristics of macrogranule (GG) for herbicidal efficacy by using remote-controlled aerial application (RCAA) to control annual and perennial weeds in rice paddy field, application methods, and application times of formulation types. Particle of 500 g GG having average diameter of 2.5~3 mm was over 85 percent, the bulk density of the particle was $0.2\sim0.4g\;mL^{-1}$ and the particle was water floating granule. Active ingredients and external form of halosulfuronmethyl+mefenacet GG remained stable under condition of storage stability test. The disintegration time of the GG was faster as the water temperature was increased. But disintegration time was not affected by pH on the water conditions. By using hand, spoon and power applicator, drift distances of GG were 4~5m, 7 m and 10~12 m, respectively. GG showed good herbicidal efficacy and plant safety in all of the application methods such as, using hand, spoon, power applicator and RCAA. Application times of GG, GR, SC and TB by hand in $4,000m^2$ were 38 min. 4 sec, 42 min. 20 sec, 38 min. 10 sec and 21 min. 4 sec, respectively, but application time of GG by using RCAA was 1 min 32 sec. According to appearance and characteristics of formulation types, suspension concentrate (SC) and GG were possible formulation types for RCAA.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.1
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• pp.38-43
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• 1986

This field experiment was conducted to determine the effects of shading degrees (0 : full sunlight, 25, 50 and 75%) on the early growth characteristics and winter survival of grasses. For the test different artificial shading houses were established and pasture species used were orchardgrass, timothy and perennial ryegrass. The experiment was performed at Livestock Experiment Station in Suweon, and sowing date was Aug. 25, 1984. The results are summarized as follows : 1. Generally, root length, new root length, number of new root and tillers of grasses were increased at 0% (full sunlight) of shading, followed by 25, 50 and 75% of shading degrees, in that order. Plant length and leaf elongation, however were increased at 50% of shading, followed by 75, 25 and 0%. 2. The percentage of winter killing of grasses was significantly (P<0.05) increased as the shading degrees increased. Also the percentages of winter killing were 10.1% in orchardgrass, 9.5% in timothy and 14.2% in perennial ryegrass, respectively. 3. A significant negative correlations were observed in the relationship between winter killing and tillers, new root length and number of new root of grasses. However, there were positive correlations between winter killing and plant length or leaf elongation under shading conditions. 4. As the shading degrees are increased by 0, 25, 50 and 75%, the NAR of grasses was tended to be decrease to 10.98, 11.52, 9.81 and 6.12 g/$m^2$/day, in that order. Also there was a negative correlation (r=-0.5943*) between winter killing and NAR of grasses, and NAR of orchardgrass, timothy and perennial ryegrass were 8.58, 8.53 and 11.71 g/$m^2$/day, respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.106-116
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• 2001

A serious of studies on the fishing gear and system of the East Sea trawl fishery was carried out to improve the fishing efficiency and the working conditions. As the first step of these studies, the fishing gear and system of the traditional East Sea trawl were checked in order to solve the some problems, such as the poor sheering efficiency of net mouth, the inconvenient fishing system of the side trawl and etc. And then the fishing system was reorganized from the side trawl into the stern trawl by setting up the net drum system on the stern deck, and introduction of two types of new designed nets, one for mainly the midwater trawl and the other for the bottom trawl. The results of the field experiment on the modified system and nets can be summarized as follows : 1. the modified system was well worked and could save the man-labour by about 80%. 2. The sheering efficiency of the improved net, A type was improved to 20 m height and 30 m width in the net mouth, and that of B type net, to 10 m height and 33 m width, compared with 1.5 m height and 15 m width in the traditional net. 3. Catch efficiency of pink shrimp in A or B type net was better about 3 or 5 times than that of traditional net, and in B net, for herring and other bottom fishes is better about 2 times than that of the traditional net.

• Research in Plant Disease
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• v.7 no.3
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• pp.155-163
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• 2001

Two attenuated Cucumber mosaic virus (CMV) isolates, Paf-CMV and Rs2-CMV that had been selected from CMV isolates associated with satellite RNA (satRNA) were tested for cross-protection effect in pepper plants. The viruses selected as attenuated strains appeared to be identical serologically and physically to the challenge virus (Mf-CMV), but they were lower in the dilution end-point of infectivity of crude sap than Mf-CMV When symptoms were observed in several indicator plants after inoculation, Paf-CMV and Rs2-CMV were symptomless or showed mild mosaic symptoms while another satRNA isolate Ap-CMV developed severe mosaic symptoms on the leaves as Mf-CMV. The nucleotide sequences of the satRNAs were determined by sequencing full-length cDNA clones. Paf-, Rs2- and Ap-satRNAs were 386, 335, and 347 nucleotides long, respectively, The sequences were then compared with the other known Y-satRNA, revealing that nucleotide sequences of the satRNAs consisted of 5'- and 3'-terminal conserved regions. However variations occurred on the middle regions of the sequences, especially those related to symptom interference, showing significant differences between Paf-satRNA and other isolates. Infectious transcripts of Paf-satRNA and Rs2-satRNA induced mild mosaic symptoms in pepper plants when supported by genomic RNAs of Mf-CMV. Under greenhouse conditions, Paf-CMV and Rs2-CMV were tested for cross-protection effect in pepper and tobacco (Nicotiana tabacum cv, Xanthi nc) plants against Mf-CMV. No symptoms were developed on the plants vaccinated with Paf-CMV until 3 weeks after inoculation with the virulent strain; however another attenuated isolate, Rs2-CMV, showed less effectiveness in cross-protection. Depending on the concentration of the challenged virus, symptoms sometimes appeared later in the upper leaves. However, in plants challenged with low concentrations (below 0.2 mg/ml) of the challenge inoculum, symptoms caused by the virulent strain did not develop on the plants vaccinated with Paf-CMV. In the field experiments, the number of pepper plants with severe mosaic symptoms in the control plots was progressively increased after transplanting and reached approximately 50% after 50 days. On the other hand, the incidence of mosaic disease appeared very low on the plants that had received the protective inoculation with Paf-CMV.

• Research in Plant Disease
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• v.14 no.3
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• pp.143-152
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• 2008

Mixed-planting of two rice cultivars, HP ('Hopyeongbyeo') and NP ('Nampyeongbyeo'), having a dissimilar susceptibility to rice blast was practiced for chemical-free control of rice blast in the field. The HP/NP combination was selected for applying under mechanized agricultural conditions. Because they have similar genetic characteristics such as seed germination and heading time, culm length, rice quality and size of rice grains except susceptibility to blast. Incidence of panicle blast was reduced 50.4 % compare with supposed blast incidence by HP/NP mixed-planting when the seeds of two cultivars were combined 1 to 1 as weight. Supposed blast incidence was estimated from reduction of rice blast caused by addition of a resistant cultivar NP. Race diversity of Magnaporthe oryzae was examined for correlation with control effect of HP/NP mixed-planting on rice blast. The population of dominant race KJ-101 was diminished and replaced with various co-existing races and eleven new races were appeared in mixed-planting plot. Total number of race isolated from mixed-planting plot was not largely different from mono-culture. However, detection frequency of the new race was increased and variation of the population size of each race was decreased in mixed-planting plots. It was shown that a biased community with a dominant race (KJ-101 or KI-181) was altered to a balanced one of coexisting races. From these results, it was supposed that the balanced diversity among co-existing races within a community might be correlated to control effect by HP/NP mixed-planting on rice blast. Further more, it should be studied that genetic characteristics of the individual race including a virulence on cv. HP and NP was examined for verifying a correlation of mixed-planting effect and race diversity.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.6
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• pp.321-327
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• 2005

Ammonia ($NH_3$) volatilization was measured from latex coated urea (LCU) and normal urea treated rice paddy under transplanting rice culture in Milyang in 2002 and 2003. The $NH_3$ volatilization from incubation experiment was significantly related with ammonium-N ($NH_4-N$) concentration and pH in the surface water. The correlation coefficients of $NH_3$ volatilization compared to the $NH_4-N$ and pH in surface water were significantly higher in urea than LCU. The $NH_3$ volatilization from both urea and LCU treatments was not increased in surface water of pH less than 8.0, while $NH_3$ volatilization increased significantly in the surface water of pH over 8.0. The results in the field experiment indicated that $NH_3$ volatilization after top-dressing of urea increased rapidly with increasing $NH_4-N$ concentration in soil and floodwater, and highest from 7 to 10 days after top-dressing. The amount of $NH_3$ volatilized from urea treatment was in the range of $4.9-8.4kg\;N\;ha^{-1}$. The variations of $NH_3$ volatilization in 2002 and 2003 were caused by changed N dynamics due to the different weather conditions such as rainfall and temperature. The amount of $NH_3$ volatilized from LCU treatment was significantly reduced compared to that of urea. The reason for the reduced $NH_3$ volatilization in LCU treatment would be due to the lower concentration of $NH_4-N$ in floodwater. The amount of $NH_3$ volatilized from LCU treated rice paddy was in the range of $1.2-1.8kg\;N\;ha^{-1}$, and the loss of N by ammonia volatilization was 2.0-2.3%. Loss of N by $NH_3$ volatilization with LCU treatment was reduced by 75-79% comparing to urea treatment.