• Korean Journal of Environmental Agriculture
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• v.15 no.2
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• pp.217-222
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• 1996

A green-house experiment was conducted to know the performance of Chinese cabbage and radish applied with simulated acid rain(SAR) on the leaf and/or soil. The pHs of SAR and normal water were 2.7 and 6.0, respectively. The pHs of SAR and normal water applied on leaf/soil were 6.0/6.0, 6.0/2.7, 2.7/6.0, and 2.7/2.7 and they were applied fifteen times at the two- or three-day intervals with 10mm at a time. Leaf application of SAR caused brown spots in both crops, while no such symptoms were observed in soil application. SAR applied on the leaf or soil increased chlorophyll content significantly in Chinese cabbage, but slightly in radish. Leaf or soil application of SAR did not affect N, P, and K concentrations in both crops. The sulfur content in radish leaf increased by leaf or soil application of SAR, while in the root it increased by soil application only. Yield of Chinese cabbage was not affected by SAR, while both leaf and root yields of radish were significantly reduced by leaf application of SAR compared with soil application.

• Korean Journal of Environmental Agriculture
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• v.15 no.4
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• pp.419-424
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• 1996

A green house experiment was conducted to investigate the performance of Chinese cabbage and radish and changes in soil chemical properties after application of different amounts of simulated acid rain (SAR). About 10mm of normal water (pH 6.0), 5mm of SAR followed by 5mm of normal water, and 10mm of SAR were applied 24 times at the two-day intervals. The results obtained are summarized as follows : 1. Visible symptoms were dark brown, red brown, or grey brown leaf spots, reduced leaf size, or some times wrinked leaves in both crops. The visible symptoms started after the third application of SAR. The degree of damages was greater as the amounts and the number of times of SAR application increased. 2. Chlorophyll contents of SAR applied leaves decreased as the amounts of SAR application increased. 3. As the amounts of SAR increased, length, diameter, and fresh weight of Chinese cabbage heads and radish roots decreased. 4. In both crops sulfur content increased, while calcium content decreased as the amounts of SAR increased. Contents of N, P, K, and Mg were not significnatly affected by the amounts of SAR. 5. SAR decreased soil pH and exchangeable cations (Ca, Mg, K), while increased soil sulfur content.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.323-328
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• 1997

Runoff of phorate, soil insecticide, were measured under simulated rainfall conditions in field using small test plot$(120\;cm{\times}120\;cm)$ at the loam area and loamy sand area. Fish acute toxicity tests were performed with runoff water to elucidate its toxicological effect on organisms in ecosystem. The average concentrations of phorate in runoff water from loam and loamy sand soil were 11.3 ppb and 4.8 ppb, respectively. However, there was no significant concentration difference between the heavy and the light rain. With loam soil, average runoff rates were 1.31 and 0.18%, while with loamy sand soil those were 0.48 and 0.012% under the heavy and the light rain conditions, respectively. Total average runoff rate was 0.50%. With killifish, no mortality was observed in runoff water from loamy sand soil, whereas half of the population was dead in runoff water from loam soil when it was diluted to 54.4% content.

• Journal of Korea Water Resources Association
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• v.44 no.9
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• pp.721-730
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• 2011

The objective of this study is to assess the availability of streamflow simulation using Radar-AWS Rain rate (RAR) data which is produced by KMA on real-time. Chuncheon dam upstream basin is selected as study area and total area is 4859.73 $km^2$. Mean Areal Precipitation (MAP) using AWS and RAR are calculated on 5 subbasin. The correlationship of hourly MAPs between AWS and RAR is weak on ungauged subbasins but that is relatively high on gauged ones. We evaluated the simulated discharge using the MAPs derived from two data types during flood season from 2006 to 2009. The simulated discharges using AWS on Chuncheon dam (gauged basin) are well fitted with measured ones. In some cases, however, discharges using AWS on Hwacheon dam and Pyeonghwa dam with some ungauged subbasins are overestimated on the other hand, ones using RAR in the same case are well fitted with measured ones. The hourly RAR data is useful for the real-time river forecast on the ungauged basin in view of the results.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.335-340
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• 1996

A green house experiment was conducted to investigate the growth of Chinese cabbage, radish and soybean and change in the chemical properties of the soil after the 10mm application of the simulated acid rain(SAR) of pH 2.7 in the form of sprinkle and mist. It was applied 30 times for Chinese cabbage and radish and 62 times for soybean at the two-day intervals. The results obtained are summarized as follows: 1. Visual damages caused by SAR were dark-brown or red brown leaf spots in Chinese cabbage, and dark-brown and wrinkled leaf margins in radish and soybean. 2. The degree of visual damages became severer as the number of SAR applications increased and it was severer with mist than with sprinkle of SAR. 3. Chlorophyll content was reduced by SAR, but it was not affected by the form of SAR application(sprinkle or mist) in all crops, although it was slightly lower with mist than with sprinkle of SAR. 4. Fresh weight of Chinese cabbage heads and radish roots and grain yield of soybean were reduced by SAR, and were not affected by the form of SAR application. 5. Contents of K, Ca, and Mg in leaves were reduced, while S content increased by SAR in all crops. The forms of SAR application did not affect contents of mineral nutrients in all crops. 6. SAR decreased soil pH and the contents Ca, Mg, and K of soil, while increased $SO_4$ content. However, the contents of soil organic matter, N, and P were not affected by SAR. Forms of SAR application did not affect soil chemical properties either.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.341-347
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• 1996

A green-house experiment was conducted to investigate the growth of Chinese cabbage, radish, and soybean and changes in soil chemical properties after application of 5 and 10mm of pH 2.7 simulated acid rain(SAR) followed by 0, 5, and 10mm of pH 6.0 normal water at the three-day intervals 20 times for Chinese cabbage and radish and 42 times for soybean. The results obtained are summarized as follows: 1. Visual damages by SAR were white-yellow leaf spots, dark brown or light green leaf color, and wrinkled leaf margins in all crops. The degree of visual damages was severer at 10mm than at 5mm SAR and it was reduced as the amounts of normal water increased after SAR application. 2. Chlorophyll content was higher at 10mm than at 5mm SAR application and increased as the amounts of normal water increased after SAR application in all crops. 3. Fresh weights of Chinese cabbage heads and radish roots and grain yield of soybean were higher at 10mm than at 5mm SAR, while they increased as the amounts of normal water increased at the same SAR level. 4. Changes in the mineral contents of plants were not consistent, while S content in radish and soybean increased as the amounts of SAR increased. 5. SAR lowered soil pH, while it increased soil N and S contents. Contents of soil organic matter, P, and exchangeable Ca, Mg, and K were not affected by the amounts of SAR.

• Atmosphere
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• v.34 no.3
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• pp.305-317
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• 2024

The study examines the effects of parameters that define the characteristics of raindrops on the simulated precipitation during the summer season over Korea using the Weather Research and Forecasting (WRF) Double-Moment 6-class (WDM6) cloud microphysics scheme. Prescribed parameters, defining the characteristics of hydrometeors in the WDM6 scheme such as a_R, b_R, and f_R in the fall velocity (V_R) - diameter (D_R) relationship and shape parameter (𝜇_R) in the number concentration (N_R) - D_R relationship, presents different values compared to the observed data from Two-Dimensional Video Disdrometer (2DVD) at Boseong standard meteorological observatory during 2018~2019. Three experiments were designed for the heavy rainfall event on August 8, 2022 using WRF version 4.3. These include the control (CNTL) experiment with original parameters in the WDM6 scheme; the MUR experiment, adopting the 50th percentile observation value for 𝜇_R; and the MEDI experiment, which uses the same 𝜇_R as MUR, but also includes fitted values for a_R, b_R, and f_R from the 50th percentile of the observed V_R - D_R relationship. Both sensitivity experiments show improved precipitation simulation compared to the CNTL by reducing the bias and increasing the probability of detection and equitable threat scores. In these experiments, the raindrop mixing ratio increases and its number concentration decreases in the lower atmosphere. The microphysics budget analysis shows that the increase in the rain mixing ratio is due to enhanced source processes such as graupel melting, vapor condensation, and accretion between cloud water and rain. Our study also emphasizes that applying the solely observed 𝜇_R produces more positive impact in the precipitation simulation.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.76-83
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• 2016

In recent, the series of extreme storm events were occurred by those continuous typhoons and the severe flood damages due to the loss of life and the destruction of property were involved. In this study, we call Mega flood for the Extreme flood occurred by these successive storm events and so we can have a hypothetical Mega flood by assuming that a extreme event can be successively occurred with a certain time interval. Inter Event Time Definition (IETD) method was used to determine the time interval between continuous events in order to simulate Mega flood. Therefore, the continuous extreme rainfall events are determined with IETD then Mega flood is simulated by the consecutive events : (1) consecutive occurrence of two historical extreme events, (2) consecutive occurrence of two design events obtained by the frequency analysis based on the historical data. We have shown that Mega floods by continuous extreme rainfall events were increased by 6-17% when we compared to typical flood by a single event. We can expect that flood damage caused by Mega flood leads to much greater than damage driven by a single rainfall event. The second increase in the flood caused by heavy rain is not much compared to the first flood caused by heavy rain. But Continuous heavy rain brings the two times of flood damage. Therefore, flood damage caused by the virtual Mega flood of is judged to be very large. Here we used the hypothetical rainfall events which can occur Mega floods and this could be used for preparing for unexpected flood disaster by simulating Mega floods defined in this study.

• Journal of Environmental Science International
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• v.26 no.5
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• pp.573-584
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• 2017

In order to simulate a typhoon precisely, the satellite observation data has been assimilated using WRF (Weather Research and Forecasting model) three-Dimensional Variational (3DVAR) data assimilation system. The observation data used in 3DVAR was GPS Radio Occultation (GPS-RO) data which is loaded on Low-Earth Orbit (LEO) satellite. The refractivity of Earth is deduced by temperature, pressure, and water vapor. GPS-RO data can be obtained with this refractivity when the satellite passes the limb position with respect to its original orbit. In this paper, two typhoon cases were simulated to examine the characteristics of data assimilation. One had been occurred in the Western Pacific from 16 to 25 October, 2015, and the other had affected Korean Peninsula from 22 to 29 August, 2012. In the simulation results, the typhoon track between background (BGR) and assimilation (3DV) run were significantly different when the track appeared to be rapidly change. The surface wind speed showed large difference for the long forecasting time because the GPS-RO data contained much information in the upper level, and it took a time to impact on the surface wind. Along with the modified typhoon track, the differences in the horizontal distribution of accumulated rain rate was remarkable with the range of -600~500 mm. During 7 days, we estimated the characteristics between daily assimilated simulation (3DV) and initial time assimilation (3DV_7). Because 3DV_7 demonstrated the accurate track of typhoon and its meteorological variables, the differences in two experiments have found to be insignificant. Using observed rain rate data at 79 surface observatories, the statistical analysis has been carried on for the evaluation of quantitative improvement. Although all experiments showed underestimated rain amount because of low model resolution (27 km), the reduced Mean Bias and Root-Mean-Square Error were found to be 2.92 mm and 4.53 mm, respectively.

• Water for future
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• v.20 no.4
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• pp.267-278
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• 1987

This study aims at the decision of geomorphologic instantaneous unit hydrograph(GIUH) model parameter fore the ungaged or the data deficiented Basin, to analyze rainfall runoff relation in river basin by applying queueing theory with geomorphologic factors.The concept of GIUH model is based upon the principle of queueing theory of rain drops which may follow many possible routes during rainfall period within watershed system to ist outlet. Overland flow and stream flow can be simulated, respectively, by linear reservoir and linear channel conceptual models. Basically, the model is a mon-lineal and time variant hydrologic system model. The techniques of applying are adopted subarea method and mean-value method, the watershed is divided according to its stream number and order. To prove it to be applicable, the GIUH model is applied to the Wi-Stream basin of Nak-Dong River(Basin area; 475.53$\textrm{km}^2$), southen part of Korea. The simulated and the observed direct runoff hydrographs are compared with the peak discharge, times to peak and coefficients of efficiency, respectively, and the results show quite satisfactory.Therefore, th GIUH model can be extensively applied for the runoff analysis in the ungaged and the data deficiented basin.