• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.211-216
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• 1986

To establish a suitability grouping system of paddy soils for double or multiple cropping with rice which is intensively practiced in the southern parts of Korea, a few basic experiments were carried out for two years. The results are summarized as follows; 1. The potential productivities of the paddy soils which were tested without any fertilizer in the pots of subsoil samples by the double cropping of rice and other upland crops were resulted that the soils of "Moderately well drained" fine silty textured were the highest while the soils of "Poorly drained" sandy were the lowest, and the productivities could be clearly comparable according to the differences of soil conditions. 2. The decomposability of organic matter also was higher in the soils of "Moderately well drained" than the "Imperfectly drained". The coarse loamy and coarse silty textured soils were high in the upland condition and in the early stages of submerging while the fine loamy and fine silty textured soils were high at the late stage of submerging in the rates of organic matter decomposition. 3. The days to be reached to tillable condition after rainfall in fine loamy textured soils were about 5 days earlier than the clayey soils. The period of tillable condition of fine clayey soils with "Moderately well drained" was the longest and that of the fine loamy textured soils was the shortest. But the soils with "Imperfectly drained" were not clear among soil textural classes. 4. The lower the ground water table the higher was the productivity indices. The variation of ground water table in the medium textured soils was higher than the both of coarse and fine textured soils among "Moderately well drained". But it was observed the opposite in the soils of "Imperfectly drained".

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.4
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• pp.277-283
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• 2018

The crop growth model has been widely used for climate change impact assessment. Crop growth model require genetic coefficients for simulating growth and yield. In order to determine the genetic coefficients, regional growth monitoring data or yield trial data of crops has been used to calibrate crop growth model. The aim of this study is to verify that yield trial data of corn is appropriate to calibrate genetic coefficients of CERES-MAIZE. Field experiment sites were Suwon, Jinju, Daegu and Changwon. The distance from the weather station to the experimental field were from 1.3km to 27km. Genetic coefficients calibrated by yield trial data showed good performance in silking day. The genetic coefficients associated with silking are determined only by temperature. In CERES-MAIZE model, precipitation or irrigation does not have a significant effect on phenology related genetic coefficients. Although the effective distance of the temperature could vary depending on the terrain, reliable genetic coefficients were obtained in this study even when a weather observation site was within a maximum of 27 km. Therefore, it is possible to estimate the genetic coefficients by yield trial data in study area. However, the yield-related genetic coefficients did not show good results. These results were caused by simulating the water stress without accurate information on irrigation or rainfall. The yield trial reports have not had accurate information on irrigation timing and volume. In order to obtain significant precipitation data, the distance between experimental field and weather station should be closer to that of the temperature measurement. However, the experimental fields in this study was not close enough to the weather station. Therefore, When determining the genetic coefficients of regional corn yield trial data, it may be appropriate to calibrate only genetic coefficients related to phenology.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.22-32
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• 1985

Optimum pasture management during the summer season is an important factor to maintain good regrowth and persistence of pasture in Korea. This experiment was carried out to investigate the effects of the cutting management on the dead plant, weed appearance, regrowth and carbohydrate reserves in stubble, and dry matter yield of tall fescue dominated pasture during the mid summer season. For the test, a split plot design with 4 replications was treated with 2 different the third cutting times (July 12 and Aug. 4) as the mainplots, and 3 different cutting heights (3, 6 and 9 cm) at the third cut as the subplots, and the experiment was done at the experimental field of the Livestock Experiment Station, in Suweon, 1984. The results obtained are summarized as follows: 1. Considering the meteorological conditions during the experimental period, the temperature was a little higher by $2^{\circ}C$ than that of average year, especially the first and second decade of August were high. And the precipitation of 1984 tended to be low when compared with the average year. 2. Temperature of soil surface and underground tended to increase by $1-3^{\circ}C$ as the stubble height was low during the summer season. 3. Regrowth leaf length and leaf area after the third cut increased significantly with the high cutting height at the third cut. 4. A significant higher total nonstructural carbohydrate (TNC) content in stubble after the third cut was observed in the high stubble cut on July 12. The results indicate that the high stubble height reserves more carbohydrates for early regrowth stage after the third cut when compared with the low stubble. On Aug. 4, however, the recovery of TNC contents after the third cut was not effective due to high temperature and rainfall. 5. The percentage of dead plant after the third cut was found to be high with the low cutting height during the mid summer season (p<0.05). 6. With the low stubble height on July 12 cut, it was appeared that the percentage of weed was significantly increased (p<0.05), and main weeds appeared after the third cut were Echinochloa crusgalli>Digitaria sanguinalis>Cyperus iria>Rumex crispus, and so on. In case of cut on Aug. 4, weed appearance was no difference at three cutting heights. 7. Dry matter yield at the third cut was increased in the plot of cutting on Aug. 4 and stubble height (p<0.05). However, yields at the fourth and fifth cut were increased with high stubble height (p<0.05), regardless of harvest time. 8. In total dry matter yield after the third cut, there was no significant difference between the cutting time and forage yield. However, total yield on July 12 was increased with the high stubble height (p<0.05). 9. From the above results, it is suggested that the 9 cm cutting height during the mid summer season is the most effective for good regrowth, weed control and forage yield of tall fescue dominated pasture.

• Journal of Korean Society of Forest Science
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• v.5 no.1
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• pp.22-26
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• 1966

As a series of studies on the behaviour of Pine gallmidge (Theccdiplosis japonensis Uehida ei Inoaye), the season of the larval hibernation in winter as well as the season of the attack of adults on pine needles in the vicinity of Seoul were observed, and following results were obtained. 1. The larvae get out of the galls and fall into the ground for the hibernation commencing from the end of September and finishing by the end of January of the next year. 2. About 76% of the whole larvae fell down during the month of November. 3. The frequency and the duration of raining mainly influenced the larval falling into the ground but temperature, humidity and the quantity of rainfall was not likely influence upon it. 4. As many as 47,000 larvae were counted per 1.5 square meter of the ground under the crown of the damaged trees. 5. When pine needles were isolated by fine linen-net-bag to keep the needles from the oviposition of the adults of the insect, at six different season; -i.e. 30th, May, 6th, 10th, 15th, 25th, and 30th June, the percentages of the damage were 80%, 50%, 36%, 19%, 20% and 1% respectively, while the damage of the control was 91%.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.69-79
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• 2013

This paper presents a two-stage geostatistical integration approach that aims at downscaling of coarse scale remote sensing data. First, downscaling of the coarse scale sedoncary data is implemented using area-to-point kriging, and this result will be used as trend components on the next integration stage. Then simple kriging with local varying means that integrates sparse precise observation data with the downscaled data is applied to generate thematic information at a finer scale. The presented approach can not only account for the statistical relationships between precise observation and secondary data acquired at the different scales, but also to calibrate the errors in the secondary data through the integration with precise observation data. An experiment for precipitation mapping with weather station data and TRMM (Tropical Rainfall Measuring Mission) data acquired at a coarse scale is carried out to illustrate the applicability of the presented approach. From the experiment, the geostatistical downscaling approach applied in this paper could generate detailed thematic information at various finer target scales that reproduced the original TRMM precipitation values when upscaled. And the integration of the downscaled secondary information with precise observation data showed better prediction capability than that of a conventional univariate kriging algorithm. Thus, it is expected that the presented approach would be effectively used for downscaling of coarse scale data with various data acquired at different scales.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.575-585
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• 1997

A daily runoff system was constructed to support decision making for water use in the downstream region of multipurpose dams in the Han River. The daily runoff system used the modified model from NWSRFS by Tabios III et al. (1986), and potential evapotranspiration was computed from Penman equation. DWOPER was used for channel routing. While the North Han River is the main river reach in the channel routing system, the South Han River and the Soyang River became tributaries. The rainfall-runoff model was calibrated and verified for five subbasins. Daily runoffs were simulated with the hydrometeorological data in 1986 and1990. The simulations were performed from April to November, and the sum of computed discharges for seven or thirty days were compared with actual releases of the downstream dams. It showed the average absolute errors of 8.7 ~31.6%. The sum of total discharges were 10% or less. While stage errors were produced by 0.5 m or less at Yoju station in the ease of simulation from April to August in 1986, the errors kept under 0.2 m since September. In the simulation for 1990, we compared two simulation results. One is produced from real internal and downstream boundary conditions and the other is one from internal and downstream boundary conditions fixed arbitrarily. The two cases showed similar results.

• Journal of Korea Water Resources Association
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• v.38 no.4 s.153
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• pp.301-311
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• 2005

The purpose of this study is to assess the quantitative effect of stream discharge due to land use changes. The upstream watershed of Pyeongtaek gauging station of Anseong-cheon ($592.6\;km^2$) was adopted. To accomplish the purpose, firstly, trace land use changes for the selected watershed which have some changes of land use by using Landsat images of 1986 and 1999 of the watershed and secondly, analyse the quantitative effect of stream discharge due to land use changes by applying GIS- based distributed hydrologic model KIMSTORM. The model was calibrated and verified at 2 locations (Pyeongtaek and Gongdo) by comparing observed with simulated discharge results for 7 storm events from 1998 to 2003. Model output was designed to provide information of land use impact on runoff components in the watershed and the sensitivity of impact level of each land use category on storm runoff. Land use impact was evaluated with the land use data sets for 1986 and 1999 for the same rainfall condition (160.5 mm). Area decrease of 4.8 percent of forest and 4.0 percent of paddy field during 13 years (1986 - 1999) within the watershed caused a 30.3 percent increase of peak runoff and a 9.3 percent increase of runoff volume.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.38-43
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• 2000

As the first step of a research on the establishment of control strategy for grapevine diseases and insects, the current status of pest control and yield losses by them were surveyed from grapevine growers of Korea. For insects, the most difficult to control was a grapevine stem borer and a grapevine clearwing moth was the next. On the other hand, several diseases including anthracnose, downy mildew, powdery mildew, bird's eye rot, leaf blight, were answered by the growers. The occurrence of the pests varied to the cultural practices. Yield loss was more serious in rainfall intercept culture than in plastic film house culture and diseases caused more loss in yield than insects did. However, the grapevine grower's potential for the identification of the kinds of pests was not high enough. When the pest was observed, the growers consulted mainly with local pesticide dealers or neighbouring growers and usually applied the pesticides prescribed by the dealer. More than half of the growers did not use pest control calendar, and most of the growers applied pesticides before any symptom appeared. Also, more than half of the growers applied mixture of at least more than 1 kind of pesticide and nutrients. Insecticides were applied less than 5 times during the season, but it was more than 6 times for fungicides. In the pesticide selection, the growers checked control effect first, regardless of the registration, and the pest control cost per unit area varied very much depending on the growers.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.13-21
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• 2004

Temporal changes of Chl-α, physical and chemical factors were investigated by diurnal observation at 2-hour interval at three fixed stations in the western Chinhae Bay from 12 Aug. to 13 Aug. 1999. Difference of dissolved oxygen between surface and bottom layer was maximum when the thermocline were strong. Organic distribution such as COD was affected by the growth of phytoplankton. Limitting factor was nitrogen, that is, inorganic nitrogen plays a significant role on regulating the algal growth. Surface distribution of dissolved inorganic nitrogen was very low compared to bottom layer by uptake of organisms. Maximum value of Chl-α at station C2 and C11 were observed from subsurface layer, ranges of which exceeded possibility concentration of red tide outbreak, 10 mg/㎥. On the other hand, that of C15 exist at surface layer. In this area, DIN and DIP concentrations increased by input sources such as rainfall and benthic flux before the bloom of phytoplankton. Accumulation of phytoplankton occurred at subsurface layer by the rapid uptake of DIN, especially nitrate ion, when strong thermocline existed as approach to the afternoon, which led to the increase of organics in water column and oxygen deficiency water mass at bottom layer until late at evening. Since then, DIN increases gradually as water temperature decrease to minimum. The quantitative understanding of nitrogen of fluxed to and from the various sources is necessary for environmental management.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.997-1005
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• 2013

Since the cross-sectional shape of the Nakdong river is compound type, the water stage rises up to the top of the flood plane, as the flow discharge increases during the extreme rain storm in summer. The recent increase of rainfall intensity and flood frequency results in the immersions of parks and hydrophilic facilities located in the flood plain. Therefore it is necessary to analyze the hydraulic characteristics evolved by the extreme rain storm in the flood plain. The study reach ranging from the Gangjeong Goryeong Weir and the Dalseong Weir, where several hydraulic facilities are located along the channel, was selected and numerical simulations were conducted for 42 hours including the peak flood of the typhoon Sanba. The 2-D transient model, FaSTMECH was employed and the accuracy of the model was assessed by comparing the water level between the simulation results and the measured ones at a gauging station. It showed a high correlation with $R^2$ of 0.990, AME of 0.195, and RMSE of 0.252. In addition, the inundation time, the inundation depth, the inundation velocity, and the shear stress variation in the flood plain facilities were analyzed.