• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.214-227
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• 2018

An object oriented crop model was developed to perform crop growth simulation taking into account complex interaction between biotic and abiotic factors in an agricultural ecosystem. A set of classes including Atmosphere class, Plant class, Soil class, and Grower class were designed to represent weather, crop, soil, and crop management, respectively. Objects, which are instance of class, were linked to construct an integrated system for crop growth simulation. In a case study, yield of corn and soybean, which was obtained at an experiment farm in Rural Development Administration from 1984 to 1986, were compared with yield simulated using the integrated system. The integrated system had relatively low error rate of corn yield, e.g., <4%, under sole and intercropping conditions. In contrast, the system had a relatively large underestimation error for above ground biomass except for grain compared with those observed for corn and soybean. For example, estimates of biomass of corn leaf and stem was 31% lower than those of observed values. Although the integrated system consisted of simple models, the system was capable of simulating crop yield under an intercropping condition. This result suggested that an existing process-based model would be used to have more realistic simulation of crop growth once it is reengineered to be compatible to the integration system, which merits further studies for crop model improvement and implementation in object oriented paradigm.

• Research in Plant Disease
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• v.16 no.2
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• pp.183-190
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• 2010

During the period from 1999 to 2008, we surveyed the major diseases incidence of rice in Korea. Leaf blast showed 0.85% of the diseased leaf area in 2000 and then consistently decreased to 0.02% by 2008. However, panicle blast irregularly appeared by the years depending on weather conditions for disease development from heading to milk stage of rice. Diseased lesion height of sheath blight had the lowest (10.1%) incidence in 2001 and the highest (21.4%) incidence in 2007. A negative corelation ($r=-0.88^*$) was measured between diseased lesion height of sheat blight and sunshine hours from mid- to late August. In Chunbuk, Gyeongbuk, and Gyeongnam provinces, brown spot occurrence declined since 2001, however, in Chungnam, Jeonbuk, and Jeonnam provinces, it increased since 2005. False smut drastically decreased after showing the highest incidence of 7.59% in panicles in 2000. The correlation coefficient between diseased panicles of false smut and rainfall during the late August was calculated as $0.94^{**}$. Bacterial leaf blight severely increased in the chronically infested fields in Jeonnam, Jeonbuk, Gyeongnam, and Chungnam province since 2003.

• International Journal of Highway Engineering
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• v.12 no.2
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• pp.71-79
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• 2010

The influence of fines of the frost susceptibility of subgrade soils were established by laboratory freezing system test simulating closely the thermal conditions in the field. During the winter season, the climate is heavily influenced by the cold and dry continental high pressure. Because of siberian air mass, the temperature of January is $-6{\sim}-7^{\circ}C$ on average. This chilly weather generate the frost heaving by freezing the moisture of soil and damage potential of the road structure. In the freezing soil, the ice lenses increase the freeze portion of soil by absorbing the ground water with capillary action. However, the capillary characteristics differ from the sort of soil on the state of freezing condition. In the current design codes for anti-freezing layer, the thickness of anti freezing layer is calculated by freezing depth against the temperature condition. Therefore, they have a tendency of over-design and uniform thickness without the considerations of thermal stability, bearing capacity and frost susceptibility of materials. So, it is essential for studying the appropriateness and bearing capacity besides the seasonal and mechanical properties of pavement materials to take a appropriate and reasonable design of the road structure. In this Paper, the evaluation of frost susceptibility was conducted by means of the mechanical property test and laboratory freezing system apparatus. The temperature, heaving amount, heaving pressure and unfrozen water contents of soil samples, the subgrade soils of highway construction site, were measured to determine the frost susceptibility.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.19-27
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• 2013

PURPOSES : This study aims to investigate the snow-melt effects of an underground electric heater's snow-melt system via a field performance test, for evaluating the suitability of the system for use on a concrete pavement. The study also investigates the effectiveness of dynamic measures for clearing snow after snowfall events. METHODS : In order to check the field applicability, in November 2010, specimens were prepared from materials used for constructing concrete pavements, and underground electric heating meshes (HOT-mesh) were buried at depths of 50 mm and 100 mm at the site of the Incheon International Airport Construction Research Institute. Further, an automatic heating control system, including a motion sensor and pavement-temperature-controlled sensor, were installed at the site; the former sensor was intended for determining snow-melt effects of the heating control system for different snowfall intensities. Pavement snow-melt effects on snowy days from December 2010 to January 2011 were examined by managing the electric heating meshes and the heating control system. In addition, data on pavement temperature changes resulting from the use of the heating meshes and heating control system and on the dependence of the correlation between the outdoor air temperature and the time taken for the required temperature rise on the depth of the heating meshes were collected and analyzed. RESULTS : The effects of the heating control system's preheat temperature and the hot meshes buried at depths of 50 mm and 100 mm on the melting of snow for snowfalls of different intensities have been verified. From the study of the time taken for the specimen's surface temperature to increase from the preheat temperature ($0^{\circ}C$) to the reference temperature ($5{\sim}8^{\circ}C$) for different snowfall intensities, the correlation between the burial depth and outdoor air temperature has been determined to be as follows: Time=15.10+1.141Depth-6.465Temp CONCLUSIONS : The following measures are suggested. For the effective use of the electric heating mesh, it should be located under a slab it may be put to practical use by positioning it under a slab. From the management aspect, the heating control system should be adjusted according to weather conditions, that is, the snowfall intensity.

• Korean Journal of Remote Sensing
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• v.34 no.2_2
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• pp.419-429
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• 2018

An unmanned autonomous maritime surface system can move the vehicle to the areas for observing the ocean accidents, disasters, and severe weather conditions. Detection and monitoring technologies have been developed by the converging of the regional and local surveillance system. Wave Glider, one of the autonomous maritime surface systems, is ocean-wave propelled autonomous surface vehicle and controlled using Iridium satellite communication. In this study, we carried out two-time Wave Glider observations for 2016 and 2017 summer in the East China Sea that the area was influenced by low-salinity water. We observed the sea surface warming effect due to the low-salinity water using the regional (satellite) and local (Wave Glider) surveillance system. We also monitored the effect of the typhoon and understood the change of the ocean-atmosphere environments in real-time. New unmanned surface system with autonomous system and high endurance structure can measure comprehensively and usefully a long observation in complicated ocean environments because of connecting with other surveillance systems.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.209-217
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• 2016

The rational method is formed area, rainfall intensity and runoff coefficient that is representation of land use or surface type. A runoff coefficient is a range for a each surface conditions. Drainage Sewer Design Guideline revised at 2011 proposes return periods 10~30 year instead of 5~10 year for increasing design flood. Ponce and ASCE refer higher values of runoff coefficient require for higher values of rainfall intensity and return period, therefore runoff coefficient had to be corrected but not. In case of park, land use and surface type are different from Korea and U.S, so impervious area ratio is different. The runoff coefficient for park is estimated considering with impervious area ratio and return period. 1,004's parks in 20 cities are randomly selected for impervious area ratio and runoff coefficient is estimated. And a proportion of 30 year return period runoff coefficient to 10 year return period with rainfall duration is calculated for 69 weather stations. The estimated runoff coefficient is 0.43~0.54 for return period 10~30 year and the difference of region and rainfall duration is not significant.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_1
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• pp.519-528
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• 2012

It was pointed out that the terrain distortion of SAR image is even worse than that of optical image although SAR imagery has the advantages of being independent of solar illumination and weather conditions. It is thus necessary to correct terrain distortion in SAR image for various application areas to integrate SAR and optical image information. There has to be a clear evaluation of terrain correction of high resolution SAR image according to the quality of DEM because the DEM of study site is generally used in the process of terrain correction. To achieve this issue, this paper compared the effects of quality of Digital Elevation Model(DEM) in the process of terrain correction of high resolution SAR images, using the DEM produced from 1:5000 topographic contour maps, LiDAR DEM, ASTER GDEM, SRTM DEM. We used TerraSAR-X and Cosmo-SkyMed, as the test data set, which are constructed on the same X-band SAR system as KOMPSAT-5. In order to evaluate quantitatively the correction results, we conducted comparative evaluation with the KOMPSAT-2 ortho image of the same region. The evaluation results showed that the DEM produced from 1:5000 topographic contour maps achieved successful results in the terrain correction of SAR image compared with the other DEM data, and the widely used SRTM DEM data in various applications was not suitable for the terrain correction of high resolution SAR images.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.61 no.1
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• pp.41-49
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• 2016

This study was conducted to evaluate maize downy mildew resistance using spreader row technique in Cambodia. A total of forty maize lines were used in this experiment. Seven Korean varieties and seven breeding lines showed high infection rates (80~100%) and highly susceptible (HS) to downy mildew disease in both spring and fall. Also most of nested association mapping (NAM) parent lines were highly susceptible (HS). Meanwhile three inbred lines, Ki3, Ki11, and CML228, showed highly resistant (HR) or resistant (R) in spring and moderately resistant (MR) in fall. These three lines were already known as resistant inbred lines against downy mildew disease. It appears that spreader row technique was suitable for selection of maize downy mildew resistance in Cambodia. The incidence of downy mildew was influenced by weather conditions, especially relative humidity and temperature. Among several inoculation methods to screen for downy mildew resistance, this spreader row technique is effectively and easily used in the field of Southeast Asia.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.2
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• pp.99-106
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• 2011

Here we reported an analyzing result for the relationship between climatic variables and rice(c.v. Odaebyeo and Ilpumbyeo) yield characteristics (including some growth characteristics) based on a long-term observed data at GARES and at KMA for rice and weather, respectively. Most of crop parameters investigated, such as heading date, culm height, panicle number $m^{-2}$, grain number $panicle^{-1}$ ripening rate, 1,000 grain weight and yield were strongly affected by wind velocity and relative humidity, as well as by daily mean air temperature, precipitation, sunshine hours and daily variations in air temperature depending on variety and crop developmental stages. Air velocity and relative humidity had not been studied as climatic variables affecting on the characteristics of rice growth and yield, however, they turned out to affect all the characteristics of rice investigated, especially ripening rate and yield, as much as any other climatic variables in this study. Air velocity appeared to affect highly the culm height and yield of Odaebyeo and ilpumbyeo. Relative humidity appeared to affect highly grain number and ripening rate of Odaebyeo and yield of Ilpumbyeo. Consequently Rice yield revealed to increase in the climatic conditions of high air velocity and low relative humidity.

• Journal of Environmental Impact Assessment
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• v.23 no.5
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• pp.406-416
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• 2014

When abnormal taste and odor were detected in the tap water of the North-Han river watershed during the dry season in late 2011, excessive nutrients with algal growth in the Lake Uiam and weather factors were considered to be among its causes. The nutrients, in particular, originated from domestic sewage in the Chuncheon area. This study was conducted to investigate relations between the algal growth in the Lake Uiam and the contribution of nutrients from public sewage treatment works (PSTWs) in Chuncheon city, and based on this to analyze the environmental impact. Nutrients in the Lake Uiam have already been accumulated to the level of eutrophication. Even in winter, the conditions in the lake such as retention time and water temperature were favorable to boost algal growth. After phosphorus treatment processes were introduced, the PSTWs in the Lake Uiam watershed were able to reduce the total phosphorus loads by 43%. The algal concentrations in the Lake Uiam also dropped by about 7%. The nitrogen treatment efficiencies in the PSTWs, on the other hand, remained almost the same after the introduction of the phosphorus treatment processes. To solve these problems more efficiently, it is necessary to develop management strategies for the upstream area of the Lake Uiam and set plans to improve nitrogen treatment operation and management for the PSTWs in Chuncheon.