• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5417-5422
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• 2013

This research was performed in order to improve the goodness of fit of paddy rice production forecasting using MODIS images and to find out appropriate explanatory variables in the forecasting model. The aim of this paper is to review the use of satellite images for the survey of paddy rice production in Korea. Many developed countries, including the United States, Australia, and Japan, have been using satellite images to produce agricultural statistics such as crop production, cultivated acreage, etc. The survey accuracy of crop production by using satellite images, however, is not satisfied in practical use. In this paper, we reviewed several methods to increase the survey accuracy of rice production statistics, gained from satellite images. Rice was selected for this study because its cultivated area and production amount could be more easily identified than other crops by using satellite images. The MODIS images were used because they involved more appropriate images to estimate and analyze rice production. This study estimated yield functions by using the NDVIs, gained from paddy rice yields and annual average isothermal lines, and the meteorological variables such as sunshine hours, rainfall, and temperature during ripening stage. As a result of yield function estimation, the goodness of fit(R-squared) for the models was shown from 0.768 to 0.891. In this study, it is noteworthy academically and practically that vegetation index(NDVIs) identified by annual average isothermal lines and meteorological variables are very useful for estimating yield functions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.17-25
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• 2017

Owing to recent climate change, the scale of rainfall tends to increase gradually and the risk of flooding has increased. Therefore, the importance of improving the levee management and disaster response is increasing. Levee management in Korea is carried out at the level of damage recovery after the occurrence of damage. Therefore, it is necessary to develop a technology for predicting and managing the levee safety with proactive river management. In this study, a method to estimate the safety against erosion and overflow was suggested. A map of levee safety that can be used as basic data is presented by displaying the levee safety on the map. The levee erosion safety was calculated as the ratio of the internal and external force for each shore type. The levee overflow safety was calculated as the ratio of the maximum conveyance and design flood. The maximum conveyance was a discharge when the level of the river was equal to the level of the levee crown. The levee safety was classified into 5 grades: very safe, safe, normal, dangerous, and very dangerous. As a research area from downstream of Nam River Dam to Nakdong River Junction, the levee safety against erosion and overflow was estimated for all levees and all cross-sections of the river. The levee safety was displayed on a map using GIS. Through the levee safety map as a result of this study, the levee safety can be observed intuitively. Using the levee safety map, a maintenance plan for a river can be easy to build. This levee safety map can be used to help determine the priority of investment for efficient budget used.

• Atmosphere
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• v.20 no.3
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• pp.239-246
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• 2010

In this study, the climatological characteristics of the landfall typhoons on North Korea are surveyed to estimate the frequency, the intensity, the track, and their damage. The data for the period of 1951-2008 are used from both RSMC (Regional Specialized Meteorological Center) Tokyo Typhoon Center and NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research), EM-DAT (Emergency Events Database). There are the ten highest frequencies from 1961 to 1965 and is one frequency for the period of both 1966-1979 and 1976-1980 respectively. Even if a clear trend on the frequency of typhoon is not defined, it is noticeable the intensity has been weak since the frequency of TS (Tropical Storm) decreased. In order to figure out both the characteristic of intensity and the relation between the typhoon track and the expansion of North Pacific High (NPH), Typhoon's tracks are classified into three types as follows: (I) landing on the west coast of North Korea through the mainland of China, (II) landing on the west coast of North Korea, (III) landing on a central/eastern part of the Korean peninsula through South Korea. More often than not, the characteristic of Type (I) is the case of a landfall after it becomes extratropical cyclone. Type(II) and Type(III) show a landfall as TS grade, by comparision. On the relation between the typhoon's track and the expansion of NPH analyzed, Type (I) shows the westward expansion while both Type (II) and Type (III) show the northward expansion and development of NPH. This means the intensity of a typhoon landfall on North Korea is variable depending on the development of NPH. Finally, only two cases are found among total five cases in EM-DAT, reportedly that North Korea was damaged. And therefore, the damage by the wind of Prapiroon (the $12^{th}$ typhoon, 2000) and heavy rainfall with Rusa (the $15^{th}$ typhoon, 2002) landing on North Korea was analyzed. Moreover, it is estimated both Prapiroon and Rusa have done badly damaged to North Korea as the economical losses of as much as six billion and five hundred-thousand US dollar, respectively.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.139-144
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• 2006

Chestnut trees have been severely damaged by the various cankers in Korea. Field surveys for elucidating the relationships between disease occurrence and environmental factors, i.e., tree age, temperature, rainfall precipitation, direction, degree of slope, chemical properties of soils, and so on, were carried out in the chestnut tree plantations located at Gyeongnam, Jeonnam, Chungnam, and Gyeonggi-Do Province. Totally, one thousand and one hundred thirty seven trees from 36 experiment plots were investigated. Trees infected by at least one of the canker fungi were estimated up to 66%. The most severely infested area was Sunchon in Jeonnam Province with the rate of 80%, while the most lightly infested area was Kongju in Chungnam Province with 39%. Disease occurrence was found to be highly correlated with tree age. The disease occurred most frequently on trees ranged from 7 to 12 years old, while it was relatively low on trees below 5 years old or above 25 years old. Canker positions on the tree formed by the pathogenic fungi were most often at 1.6-2.0m above the ground. Over five hundreds bark samples from the canker area on the tree were collected and the pathogenic fungi were isolated. The most commonly isolated fungus was identified as Cryphonectria parasitica, the chestnut blight fungus.

• Journal of Korea Water Resources Association
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• v.49 no.7
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• pp.579-588
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• 2016

Changes in precipitation due to climate change is made to induce the local and intensive rainfall, it is increasing damage caused by inland inundation. Therefore, it requires a technique for predicting damage caused by flooding. In this study, in order to determine whether this flood inundated by any route when the levee was destroyed, Which can simulate the path of the flood inundation model was developed for the SIMOD (Simplified Inundation MODel). Multi Direction Method (MDM) for differential distributing the adjacent cells by using the slope and Flat-Water Assumption (FWA)-If more than one level higher in the cell adjacent to the cell level is the lowest altitude that increases the water level is equal to the adjacent cells- were applied For the evaluation of the model by setting the flooding scenarios were estimated hourly range from the target area. SIMOD model can significantly reduce simulation time because they use a simple input data of topography (DEM) and inflow flood. Since it is possible to predict results within minutes, if you can only identify inflow flood through the runoff model or levee collapse model. Therefore, it could be used to establish an evacuation plan due to flooding, such as EAP (Emergency Action Plan).

• Journal of Wetlands Research
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• v.14 no.2
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• pp.223-235
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• 2012

In this paper, field study results about accumulation of sediments and its property in the forebay of wetland aiming at stormwater from rural area wherein intensive cow feeding lots are operated are provided. In addition, some design aspects are discussed. Amount of sediment generation in the longitudinal direction of forebay was found to be affected by hydrological factors such as rainfall depth and intensity. Nutrient contents in the sediments of this wetland were 10 times higher than those in stormwater wetland in rural area without animal-feeding lot. Total-Pb and As contents show similar level to values from the soils of surrounding watershed, but Total-Cu content was higher due to the animal feeding lots. Yearly amount of sediment generation, its depth and volume were estimated to 13tons, 23cm, and $65m^3$. Based on these results and recommended guideline by Korean Ministry of Environment, dredging frequency was found to be about 2.7years. The shape of forebay has to be carefully designed to deal with a great change in flow rate. According to the results of sediment depth analysis, instead of the present rectangular, wedge-shape forebay is more desirable in handling scouring caused by high flows.

• Journal of Korea Water Resources Association
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• v.49 no.2
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• pp.107-119
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• 2016

Since future climate scenarios indicate that extreme precipitation events will intensity, probable maximum precipitations (PMPs) without being taken climate change into account are very likely to be underestimated. In this study future PMPs in accordance with the variation of future rainfall are estimated. The hydro-meteorologic method is used to calculate PMPs. The orographic transposition factor is applied in place of the conventional terrain impact factor which has been used in previous PMPs estimation reports. Future DADs are indirectly obtained by using bias-correction and moving-averaged changing factor method based on daily precipitation projection under KMA RCM (HEDGEM3-RA) RCP 8.5 climate change scenario. As a result, future PMPs were found to increase and the spatially-averaged annual PMPs increase rate in 4-hour and $25km^2$ was projected to be 3 mm by 2045. In addition, the increased rate of future PMPs is growing increasingly in the future, but it is thought that the uncertainty of estimating PMPs caused by future precipitation projections is also increased in the distant future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.3
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• pp.117-127
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• 2020

The Early Warning System for agrometeorological hazard of the Rural Development Administration (Korea) forecasts detailed weather for each farm based on the meteorological information provided by the Korea Meteorological Administration, and estimates the growth of crops and predicts a meteorological hazard that can occur during the growing period by using the estimated detailed meteorological information. For verification of early warning system, automated weather observation network was constructed in the study area. Moreover, a real-time web display system was built to deliver near real-time weather data collected from the observation network. The meteorological observation system collected diverse meteorological variables including temperature, humidity, solar radiation, rainfall, soil moisture, sunshine duration, wind velocity, and wind direction. These elements were collected every minute and transmitted to the server every ten minutes. The data display system is composed of three phases: the first phase builds a database of meteorological data collected from the meteorological observation system every minute; the second phase statistically analyzes the collected meteorological data at ten-minutes, one-hour, or one-day time step; and the third phase displays the collected and analyzed meteorological data on the web. The meteorological data collected in the database can be inquired through the webpage for all data points or one data point in the unit of one minute, ten minutes, one hour, or one day. Moreover, the data can be downloaded in CSV format.

• Journal of Environmental Impact Assessment
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• v.27 no.3
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• pp.251-266
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• 2018

This study predicted the effect of operation pattern of flood control dam on water quality. Flood control dam temporarily impound floodwaters and then release them under control to the river below the dam preventing the river ecosystem from the extreme flood. The Hydrological Simulation Program Fortran (HSPF) and the Environmental Fluid Dynamics Code (EFDC) were adapted to predict the water quality before and after the dam construction in the proposed reservoir. The non-point pollutant delivery load from the river basin was estimated using the HSPF, and the EFDC was used to predict the water quality using the provided watershed boundary conditions from the HSPF. As a result of water quality simulation, it is predicted that the water quality will be improved due to the decrease of pollution source due to submergence after dam construction and temporary storage during rainfall. There would be no major water quality issues such as the eutrophication in the reservoir since the dam would impound the floodwater for a short time (2~3 days). In the environmental impact assessment stage of a planned dam, there may be some limitations to the exact simulation because the model can not be sufficiently calibrated. However, if the reliability of the model is improved through the acquisition of actual data in the future, it will be possible to examine the influence of the water environment according to various operating conditions in the environmental impact assessment of the new flood control dam.

• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.621-635
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• 1998

The feasibility of cloud seeding in Korea is presented from analyses of precipitation, cloud amount, satellite data, and upper air data. The daily mean precipitation over Dae-Kwan-Ryong is the largest(~4.5 mm/day), while the intensity of precipitation (amount of yearly rainfall divided by the frequency of rain days) over Southern area is above 14 mm/day, which shows the largest in Korea. Both the daily mean and the intensity of precipitation over Andong area are the smallest with values of ~2.7 mm/day and ~11 mm/day, respectively. In the meanwhile, the occurrence frequency of appropriate cloud top temperature (-10'~-30') for cloud seeding over the region has a large value (~130 days/year). The precipitation patterns of the region vary with wind direction and intensity calculated from 43 AWSs(Automatic Weather Station) and the additional 7 rain guages which were installed along Northern and Southern part of the Sobaek mountain. The Sc(Stratocumulus) cloud type over Andong is frequently observed, and Cirrus and Altostratus next. From the results, it is estimated that the feasibility of cloud seeding over the area would be high if a proper strategy of cloud seeding is set up. LCL (Lifting Condensation Level) and CCL (Convective Condensation Level) have the most frequency in 1000-950 hPa being occupied 4/9 of total analysis period and in 400-500 hPa, respectively, with both small variations from season to season. The correlation between vapor mixing ratio and CCL is the highest in Summer and the lowest in Winter. It means that the height of cumulus in Summer is high with an abundant water vapor but vice versa in Winter, and that the strategy of cloud seeding should be different with seasons.