• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.255-261
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• 2016

The present study was conducted to characterize physiological responses of aerial part according to soil water stresses in 'Mihong' peach trees. Discolorations, wilting and falling of leaves were observed in chronological order as response for waterlogging and no irrigation and the phenomena started from basal to end of shoots. Shoot growth in elongation and thickness decreased and fallen leaves were severe in waterlogged trees. Function of water uptake by roots and photosynthesis and leaf respiration decreased by waterlogging. Leaf chlorophyll contents decreased in both treatments. In waterlogging treatment, decrease of chlorophyll was observed in normal leaves with waterlogging using light microscopy. Starch content was lower in both treatment and carbohydrate content was lower in root with waterlogging. These results demonstrated that waterlogging weakened the function of soil water uptake and movement and decreased photosynthesis and fallen leaves. Finally the peach trees would wither or suffer low temperature damage through the shortage of reserve accumulations. We suggested that waterlogging damage in peach trees could be reduced to take notice of irrigation and install drainage facility to improve soil condition.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.126-138
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• 1996

The characteristics of rapid development of the low pressure system over the East Sea from 06 to 08 Nov., 1995 has been analyzed in detail by the synoptic numerical products and satellite observations. The Low system was initially triggered the development of the baroclinic leaf cloud over the border of the northern part of Korea and China and moved eastward and then developed explosively com-ma or lambda type cloud system over the East Sea. To forecast well the general development and movement of the coastal winter cyclone over the East Sea popularly in a numerical simulation by several scientists, the large baroclinicity, continuous support of water vapor, and sequential cold outbreak over the warm sea surface have been more commonly concerned about. The cyclone which the central surface pressure was dropped 40hPa within 24 hours has often accompanied strong wind and heavy snow- or rain-fall in the winter season. In all successive observations with 12-hourly satellite imagery and analyzed meteorological variables in this period, the centers of the sea-level pressure and 500hPa geopotential height associated with this cyclone were typically illustrated by moving farther eastward using GMS combined enhanced IR images. The maxi-mum wind sustained by this system with the intensity and central pressure of tropical storm was about 60 knots with the center pressure drop of 44hPa/day similar to the North American cyclonic bomb and Atlantic storm.

• Journal of Biosystems Engineering
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• v.13 no.3
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• pp.32-43
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• 1988

This study was attempted to investigate the pneumatic separation on separating unit of a combine harvester. The aerodynamic characteristics of threshed materials were analyzed by experiments. The air velocity distribution within the separation chamber was measured for various speeds of the winnower and suction fans to find out the operational and design conditions of the separating unit which would serve for reducing the grain loss from chaff outlet. The results of study arc summarized as follows: 1. Based on the separation curve of threshed materials analyzed, it was shown that three different kind. of materials-kernels, straw chaff, and leaf chaff were as a whole able to be separated pneumatically, regardless of varieties. However, a small amount of the separation grain loss may be expected to occur if the complete separation between kernels and straw chaff would be undertaken because some portion of their separation curve were overlapping. 2. The analysis of air velocity distribution showed that the separation chamber may be divided into two regions, the discharging and separating. The air velocity of the discharging region was 5-15 m/s and that of the separating region 2-5 m/s. 3. The air movement of the separation chamber may be a turbulence flow, being its speed became greater as it moves from the left to the right section of the separation chamber. The equi-speed line. of air flow had a steep gradient in between the discharging and the separation regions. The air velocity in the discharging region was much higher than the terminal velocity of kernels, because of which those kernels appearing in the region could be possibly exhausted as the grain loss from the chaff outlet. 4. The motion trajectory of threshed material in the separating region was dominantly affected by the winnower fan, on the other hand, its motion in the discharging region was affected by suction fan. 5. The grain loss from the chaff outlet was affected greatly by the winnower fan and the trace of kernel movement. It was observed that the optimum working speed to give minimum grain loss from chaff outlet for the combine tested should be maintained at 950~1,150 rpm for the winnower fan and 1,850 rpm for the suction fan. 6. It was shown that a large portion of grain loss from chaff outlet may occur when the kernels may bump against a portion of separation chamber wall and those kernels thus scattered into the discharging region were sucked by the suction fan. It was accordingly recommended that a new design of the wall of separation chamber so as to bump down kernels may be necessary to reduce grain loss from the chaff outlet.

• The Plant Pathology Journal
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• v.21 no.2
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• pp.142-148
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• 2005

Whereas most of isolates of Cucumber mosaic virus(CMV) can induce green mosaic systemic symptoms on zucchini squash, foliar symptoms of a pepper isolate of CMV (Pf-CMV)-infected zucchini squash revealed systemic chlorotic spots. To assess this biological property, infectious full-length cDNA clones of Pf-CMV were constructed using long-template RT-PCR. The complete nucleotide sequences of RNA2 and RNA3 of Pf-CMV were determined from the infectious fulllength cDNA clones, respectively. RNA 2 and RNA3 of Pf-CMV contain 3,070 nucleotides and 2,213 nucleotides, respectively. Overall sequence homology of two RNAs revealed high similarity (90%) between CMV strains, and 60% similarity to those of Tomato aspermy virus and Peanut stunt virus strains. By sequence analysis with known representative strains of CMV, Pf- CMV belongs to a typical member of CMV subgroup IA. The virus has high evolutionary relationship with Fny-CMV, but the pathology of Pf-CMV in zucchini squash was quite different from that of Fny-CMV. The pesudorecombinant virus, F1P2P3, induced chlorotic spot leaf symptom and timing of systemic symptom in squash plants, similar to the plants infected by Pf-CMV. No systemic symptoms were observed when Pf-CMVinoculated cotyledons were removed at 5 days postinoculation (dpi) while Fny-CMV showed systemic symptom at 2 dpi. These results suggest that the pepper isolate of CMV possesses unique pathological properties distinguishable to other isolates of CMVs in zucchini squash.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.2
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• pp.77-82
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• 1998

Aerenchyma development in rice (Oryza sativa L.) roots is quite important for adaptation to waterlogged or reduced soil conditions. Anatomical observations were carried out to clarify the development of schizogenous and lysigenous aerenchyma in elongating crown roots of rice. The crown roots of 3rd and 4th phytomer were taken from rice plants of the 8th leaf stage grown by hydroponic culture. The schizogenous intercellular spaces in the cortex of crown root tip were observed using a light microscope with semi ultra-thin sections and the lysigenous aerenchyma in mature tissue of crown root were observed using a cryo scanning electron microscope (cryo-SEM) with freezing fracture method. The schizogenous intercellular spaces in the root tip exist obviously in the middle portion of cortical cell layers close to the root-root cap junction, but not in root cap, stele and outer cell layers of cortex. The air spaces were formed at the junction of four neighbouring cells of inner cortex in the transverse sections, and between longitudinal cell layer connected along the root axis. Although many of those spaces were filled with liquid, some spaces seem to exist as air spaces. The lysigenous aerenchyma in the cortex, which hardly filled with liquid, emerged at 3-4 cm segment from the root tip and increased toward the basal region of root axis. The developing process of lysigenous aerenchyma was primarily separation of a radial row of cells caused by the shrinking and collapsing of cortical cells and then formation of septa along the radial cell rows by the fusion of cell wall with each other. These results suggest that the schizogenous and lysigenous aerenchyma playa role as a passage for the movement of oxygen into the root tip region where oxygen is required for respiration.

• Korean journal of applied entomology
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• v.22 no.2 s.55
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• pp.147-159
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• 1983

In general, herbicides have been classified according to selectivity, mobility. time of application, methods of application, mode of action and chemical property and structure. However, there was no generally accepted classification system for practical use in the field. The primary processes affected by the majority of herbicides are the growth process through cell elongation and/or cell division, the photosynthetic process specifically the light reaction, the oxidative phosphorylation and the integrity of the membrane systems. The usual approach in the study of the mechanism by which herbicides kill or inhibit the growth of plants is to initially determine the morphological phototoxicity systems, The mechanism by which a herbicide kills a plant or suppresses its development is actually the resultant effect of primary and secondary(or side) effects. In most instances, the death of the plant is due to the secondary effects. To induce the desired response, a herbicide must be able to gain entry into the plants and once inside, to be transported within the plant to its site(s) of activity in concentrations great enough. Obstacles to the entry and movement of herbicides in plants are generally classified by leaf and soil obstacles, translocation obstacles and biochemical obstacles, and these obstacles are also strongly influenced by plant species and by environmental factors such as light, temperature, rainfall and relative humidity. And hence, in most instances, results obtained from laboratory or greenhous vary from those of field experiment. Author attempted to classify herbicides from the field experiment using the two-dimensional ordination analysis to obtain practical information for selecting effective herbicides or to choose effective herbicide combinations for increasing herbicidal efficacy or reducing the chemical cost. Based on this two-dimensional diagram, desired herbicides or combinations were selected and further investigated for the interaction effects whether these combinations are synergistic, additive or antagonistic. From the results, it was concluded that these new approach could possibly be give more comprehensive informations about effective use of herbicide than any other systems.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.68-72
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• 2002

This study was done to implement intensity-modulated radiation therapy (IMRT) for the treatment of primary prostate cancer and to compare this technique with conventional treatment methods. A 72-year-old male patient with prostate cancer stage T2a was treated with IMRT delivered with dynamic multi-leaf collimation. Treatment was designed using an inverse planning algorithm, which accepts dose and dose-volume constraints for targets and normal structures. The IMRT plan was compared with a three-dimensional (3D) plan using the same 6 fields technique. Lower normal tissue doses and improved target coverage were achieved using IMRT at current dose levels, and facilitate dose escalation to further enhance locoregional control and organ movement during radiotherapy is an important issue of IMRT in prostate cancer.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.134-134
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• 2017

Recently, host-induced gene silencing (HIGS) system has been successfully applied into development of resistant crops against insects, fungal and viral pathogens. To test HIGS-mediated resistance in rice against rice blast fungus, Magnaporthe oryzae, we first tested possibility of movement of small non-coding RNA from rice cells to rice blast fungus. The rice blast fungus expressing GFP transgene were inoculated to transgenic rice plants ectopically expressing dsRNAi construct targeting fungal GFP gene. Expression of dsRNAi construct for GFP gene in transgenic plants significantly suppressed GFP expression in infected fungal cells indicating that small RNAs generated in plant cells can move into infected fungal cells and efficiently suppress the expression of fungal GFP gene. Consistent with these results, expression of dsRNAi constructs against 3 fungal pathogenic genes of M. oryzae in transgenic rice specifically and efficiently suppressed not only the expression of fungal pathogenic genes, but also fungal infection. The conidia of M. oryzae applied on leaf sheath of transgenic rice expressing dsRNAs against 3 fungal pathogenic genes showed abnormal development of primary hyphae and malfunction of appressorium, which is consistent with the phenotypes of corresponding fungal knock-out mutants. Taken these results together, here, we suggest a novel strategy for development of antifungal crops by means of HIGS system.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.69-79
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• 2000

Fractal geometry has become one of prospective research approaches as the complex structure of natural entities is not easily characterized by traditional Euclidean geometry. With the fractal geometry, we can better decipher the complex structure and identify natural and anthropogenic agents of landscape patterns occurring at different spatial scales. The usefulness of fractal, however, has not been fully appreciated among Korean academic societies, especially in ecological and limnological fields. We attempt to address three points in this study. First, we introduce the concept and dimension of fractal and review relevant research approaches, especially with respect to ecological and limnological phenomena. Second, we explore possible applications of fractal to some aspects of geography and land use characteristics in South Korea. For the analyses of fractal dimensions, we used data published in other studies previously and collected for this study. Data were analyzed by a perimeter/area method of fractal dimension for the spatial distribution of global solar radiation and leaf area index, and the movement of wild boars in forested landscapes of mid-eastern Korea. The same approach was also applied to the water channel of a hypothetical river and the shape of reservoirs in Yongin, Kyunggi Province. Finally, we discuss the results and key issues to consider when a fractal approach is employed in ecology and limnology.

• Journal of KIISE:Databases
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• v.31 no.2
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• pp.150-162
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• 2004

Moving objects have characteristics that they change continuously their positions over time. The movement of moving objects should be stored on trajectories for processing past queries. Moving objects databases need to provide spatio-temporal index for handling moving objects queries like combined queries. Combined queries consist of a range query selecting trajectories within a specific range and a trajectory query extracting to parts of the whole trajectory. Access methods showing good performance in range queries have a shortcoming that the cost of processing trajectory Queries is high. On the other hand, trajectory-based index schemes like the TB-tree are not suitable for range queries because of high overlaps between index nodes. This paper proposes new TR(Trajectory Riving)-tree which is revised for efficiently processing the combined queries. This index scheme has several features like the trajectory preservation, the increase of the capacity of leaf nodes, and the logical trajectory riving in order to reduce dead space and high overlap between bounding boxes of nodes. In our Performance study, the number of node access for combined queries in TR-tree is about 25% less than the STR-tree and the TB-tree.