• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.1-12
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• 2008

Remote sensing using multispectral radiometry may be a useful tool to detect drought stress in turf. The objective of this research was to investigate the correlation between drought stress and multispectral reflectance (MSR) from the turf canopy. St. Augustinegrass (Stenotaphrum secundatum[Walt.] Kuntze.) cultivars 'Floratam' and 'Palmetto', 'SeaIsle 1' seashore paspalum Paspalum vaginatum Swartz.), 'Empire' zoysiagrass (Zoysia japonica Steud.), and 'Pensacola' bahiagrass (Paspalum notatumFlugge) were established in lysimeters in the University of Florida Envirotron greenhouse facility in Gainesville. Irrigation was applied at 100%, 80%, 60%, or 40% of evapotranspiration (ET). Weekly evaluations included: a) shoot quality, leaf rolling, leaf firing b) soil moisture, chlorophyll content index; c) photosynthesis and d) multispectral reflectance. All the measurements were correlated with MSR data. Drought stress affected the infrared spectral region more than the visible spectral region. Reflectance sensitivity to water content of leaves was higher in the infrared spectral region than in the visible spectral region. Grasses irrigated at 100% and 80% of ET had no differences in normalized difference vegetation indices (NDVI), leaf area index (LAI), and stress indices. Grasses irrigated at 60% and 40% of ET had differences in NDVI, LAI, and stress indices. All measured wavelengths except 710nm were highly correlated (P < 0.0001) with turf visual quality, leaf firing, leaf rolling, soil moisture, chlorophyll content index, and photosynthesis. MSR could detect drought stress from the turf canopy.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.4
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• pp.343-348
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• 2014

We developed a simple model to predict emergence time and emergence rate of southern type garlic using the daily mean temperature. Emergence rate of garlic was decreased and emergence time was delayed on higher temperature than optimum temperature of $12.7^{\circ}C$. In the model, firstly daily emergence rate was calculated using a beta function to input daily mean temperature, then the percentage of garlic emergence was calculated using a nonlinear model with accumulated emergence rate. The model was good to describe the experimental data of growth cabinet. Also it can explain well the experimental data using temperature gradient tunnel, designed for verification of model performance. But there are 5 days of deviation between estimated and measured time of garlic emergence on the field experiment. More research is needed to develop an advanced model considering other factors, such as soil moisture.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.127-134
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• 2018

This study evaluated the effects of high air temperature and waterlogging duration on growth and yield of Kimchi cabbage. Air temperature treatments were applied with ventilation; optimal (set $20^{\circ}C$) and delayed ($30^{\circ}C$) in the greenhouses. The waterlogging treatment levels were implicated 0, 12, 24, 48, and 72 hours, respectively. The growth of Kimchi cabbage was significantly affected by waterlogging duration. The head weight decreased by combining severe waterlogging and high air temperature. Net photosynthetic rate under the combination of non-waterlogging and optimal air temperature was $22.6{\mu}mol\;CO_2{\cdot}m^{-2}{\cdot}s^{-1}$, which was the greatest, while that of 72 hours-waterlogging was rapidly decreased. The percentage of formality with 0, 12, and 24 hours-waterlogging was over 88%, however, those of 72 hours-waterlogging with optimal and delayed ventilation were 64 and 68%, respectively, which were dramatically reduced. The yields were more affected by waterlogging duration than air temperature treatment because of deducting as increased waterlogging periods. These results indicate that waterlogging treatment reduced the yield and quality of Kimchi cabbage, thus it will be feasible to enhance the harvest time when severe waterlogging in the field.

• The Korean Journal of Ecology
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• v.26 no.5
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• pp.281-287
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• 2003

We present the first analysis of moor vegetation on the Moojechi of Ulsan including syntaxonomy and syndynamics. We classified plant communities according to the Braun-Blanquet approach. In order to better understand ecological alteration processes and changing species compositions along successional gradients we also examined synecological differences using Principal Coordinate Analysis(PCoA) in terms of moisture gradient, species richness, and community structure. Classification resulted in one association and five plant communities occupying distinct moor habitats: Hypericum laxum-Eleocharis acicularis for. longiseta community, Drosera rotundifolia-Eleocharis congesta community, Platanthero-Molinietum japonicae ass. nova hoc loco, Molinia japonica-Alnus japonica community, Miscanthus sinensis-Pinus densiflora community, and Convallaria keiskei-Quercus serrata community. Due to synecological correspondences and floristic similarities in supraregional perspective, Platanthero-Molinietum can be assigned to existing higher syntaxonomic units of Molinion and Molinietalia in Braun-Blanquet system, established in Japan. We propose to extend their range and designate the new class Molinietea japonicae representative to the intermediate moor (Zwischenmoor) vegetation in Northeast Asia. PCoA resulted in four types showing a sequencess of succession: Needle spike-rush type, moor-grass type (incl. alder forest type), eulalia type, and oak forest type. A combination of edaphic conditions (soil eutrphication and soil moisture) and hydrologic patterns of moor ecosystem related to topography, occurring as result of external geophysical forces, controls inter alia spatial patterns and floristic compositions of moor plant communities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.655-668
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• 1994

Conventional deodorization filters using soil and compost reach the capacity limitation of deodorization in short period, because its removal mechanism primarily depends on adsorption. Therefore, in this study the experiment was performed on the removal of ammonia which is a strong inorganic malodor, frequently emitted from night soil treatment plants and sewage treatment plants, by seeding activated sludges on the bio-peat containing higher organic contents, water conservation capacity, permeability and lower pressure drop. As a result, in raw peat filter natural ammonia outlet was observed in consequence of pH increase resulted from ammonia ionizing in liquid phase. Ammonia removal mechanism primarily depended on the adsorption onto the anion colloidal substances in peat. In peat bio-filter, theoretical ammonium salts ratio was higher than that of raw peat, resulted from slight pH increase by microorganism activity, however, the experimetal value of ammonia-nitrogen accumulated in bio-peat was lower than that of raw peat because of nitrification by nitrifying bacteria. In the initial reaction period, adsorption was predominant in the ammonia removal mechanism, but nitrification was conspicuous after the middle period. Mass balance of nitrogen was established using experimental data of input $NH_3$ loading, output $NH_3$ loading, $NH_4{^+}$-N, $NO_x$-N, and Org-N. The critical time of unsteady state, which is the maximum activating point of microorganism in bio-filter, was determined using experimental data, and the ammonia adsorption curve was computed using regression analysis. On the basis of the results obtained by above analysis, the delay days for the saturation of adsoption capacity in peat bio-filter was calculated.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.2
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• pp.227-235
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• 1993

This study was carried out to evaluate the possibility of composting for organic solid waste from restaurants and domestics. Small three vessels were prepared which were conditioned to semianaerobic, convectional and air-blowed type. During the experiment period for 4 months, the values of volatile solid(VS) %, moisture % and carbon/nitrogen (C/N) ratio of the wastes in the vessels were stabilized, 80 % to 40-50 %, 80 % to 48-55 % and 18 to 8-10, respectively. On the basis of VS % and C/N ratio, the reactions were more adaptable to 2nd order formula than to 1st order one, Reaction rate constant of the 3 vessels were estimated, $4.96{\times}10^{-5}(day^{-1})$ in the semianaerobic type, $5.82{\times}10^{-5}(day^{-1})$ in the convectional type and $8.42{\times}10^{-5}(day^{-1})$ in the air-blowed type on VS. Compared reaction rate constants(k), it can be said that composting period shorten if air is supplied artificially and that vessels simular to those of this study are useful for household organic waste at the backyards.

• Journal of Korea Water Resources Association
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• v.49 no.1
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• pp.19-28
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• 2016

The objective of this study is the generation of the gridded flash flood index using the gridded hydrologic components of TOPLATS land surface model and statistic flash flood index model. The accuracy of this method is also examined in this study. The study area is the national capital region of Korea, and 38 flash flood damages had occurred from 2009 to 2012. The spatio-temporal resolutions of land surface model are 1 h and 1 km, respectively. The gridded meteorological data are generated using the inverse distance weight method with automatic weather stations (AWSs) of Korea Meteorological Administration (KMA). The hydrological components (e.g., surface runoff, soil water contents, and water table depth) of cells corresponding to the positions of 38 flood damages reasonably respond to the cell based hourly rainfalls. Under the total rainfall condition, the gridded flash flood index shows 71% to 87% from 4 h to 6 h in the lead time based on the rescue request time and 42% to 52% of accuracy at 0 h which means that the time period of the lead time is in a limited rescue request time. From these results, it is known that the gridded flash flood index using the cell based hydrological components from land surface model and the statistic flash flood index model have a capability to predict flash flood in the mountainous area.

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.320-324
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• 2017

Development of modern agricultural machinery and accompanying agricultural development cause soil compaction and reduce growth by stressing roots. Kalanchoe pinnata was used to investigate the impact of stress on rooting and changes in plant growth and reproduction. K. pinnata forms somatic embryos capable of asexual reproduction at the edge of leaves. Impact of root pressurization of K. pinnata on somatic embryogenesis and organ differentiation according to external stress factors was investigated by using a high concentration of agar and this phenomenon was studied histologically. Agar concentration in culture media ranged from 0.5%-1.5% to induce a compression effect on roots. The stem and leaf of K. pinnata were subjected to a microtechnique process to study changes in tissue. In vivo, K. pinnata produced 2nd and 3rd plantlets at edges of leaves from lack of water and excessive lighting conditions. In in vitro culture studies, the lower the concentration of agar, the higher the population and the higher the biomass, but plantlet did not occur in leaf bends. Conversely, as concentration of agar increased, increase in the number of individuals was low. Plantlet development occurred only in agar 1.5% medium. The difference in agar concentration was a stressor in the root of K. pinnata, and thus the pattern of asexual reproduction changed from the division method in root to a plantlet generation in leaf. This suggests root pressurization may act as stress and change in the plant reproduction pattern.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.25-33
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• 2020

To improvement the swelling characteristics of the existing cutoff wall against the moisture, the permeability of the sand, calcium bentonite and solidifier mixture according to the contact with trichloroethylene (TCE) was evaluated. Characteristics analysis and the permeability test of the research materials were performed. The permeability was decreased as the mixing ratio of the calcium bentonite was increased and it was increased as the mixing ratio of the solidifier was increased. In conclusion, when mixing 15% of calcium bentonite and more than 30% of solidifier, the permeability coefficient in the underground water movement was analyzed as more than α × 10^-4 cm/sec showing that it does not block the underground water movement. In addition, as the permeability coefficient of mixtures after TCE reaction was analyzed as less than α ×10^-7 cm/sec, it satisfied the condition of blocking layer (less than 1.0 × 10^-6 cm/sec). Therefore, the calcium bentonite and solidifier can be utilized as barrier that showing the characteristic of percolation ability conversion in soil and underground water contaminated with TCE.

• Korean Journal of Agricultural Science
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• v.2 no.1
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• pp.179-185
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• 1975

This trial was conducted for the selection of drought registance strains and other main characters of orchard grass. Some preliminary results obtained are as follows : 1. The initial growth of orchard grass in sufficient soil moisture condition showed highly significant differences among the varieties. Turkey's D=0.84. However, in proceeding the growth, the grass height among the varieties showed non-significant. 2. Addition of nitrogen fertilizer before first flowering tended to increase the grass height occationally significantly, compared to the control. 3. The survived varieties on the drought soil moisture condition had more numbers of tillering than the wilted significantly except some varieties. However, in grass height between the survival and the wilted, almost varieties showed non-significant differences. 4. In the varierties of Metia, Phyllox and Dorise, all individuals were survived in drought soil moisture condition and showed almost the same growth responces with willted ones comparatively. The plant height and the numbers of tillering of these 3 varieties were as follows: Merita; 26.4 cm 24.2 ea, Phyllox; 31.4 cm 24.6 ea. Dorise; 26.8 cm 35.6 ea.