• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.10
• /
• pp.668-676
• /
• 2018

Most reservoirs in Korea have a low water depth and are small in size. Water pollution of the reservoir is serious because of the organic matter flowing from livestock wastewater, domestic sewage, and farmland. In this study, an attempt was made to improve the water purification effect by replacing the secondary dam installed in the depression area of the agricultural reservoir with the riprap dam. To evaluate the long-term performance, a riprap dam was installed in a reservoir in Gyeonggi province and water purification effect for 36 months was measured. The field test results showed that COD was 14.6%, SS 38.6%, T-N 9.5%, and T-P 11.2%. The concentrations in the influent water exhibited a significant change according to season, and the water purification effect increased with increasing concentration of influent water. The pollutant flowing into the lake from the depression area can be blocked effectively if the secondary riprap dam for water purification is installed in the agricultural reservoir.

• Journal of Korean Society for Geospatial Information Science
• /
• v.20 no.2
• /
• pp.15-22
• /
• 2012

The variation in the wind speed with height above ground is called the wind shear profile. In the field of wind resource assessment, analysts typically use one of two mathematical relations to characterize the measured wind shear profile: the logarithmic profile (log law) and the power law profile (power law). The logarithmic law uses the surface roughness as a parameter, and the power law uses the power law exponent as a parameter. The shape of the wind shear profile typically depends on several factors, most notably the roughness of the surrounding terrain and the stability of the atmosphere. Since the atmospheric stability changes with season, time of day, and meteorological conditions, the surface roughness and the power law exponent also tends to change in time. For this study, Using the observed data from Met-mast, located in Pyeongdae, Handong in Jeju. we used the matlab and windograper to calculate roughness length and the law exponents. These calculations are similar to reference the data, but they have different ranges. In the ocean case, each reference data and calculated data was the same, but the crop area is higher than the earlier studies. In addition, the agricultural village is lower than the earlier studies.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.3
• /
• pp.266-273
• /
• 2007

The change patterns of the water quanity, water quality(WQ, exclusively COD in this study) and monthly / annual pollutant loads(PL) estimated using the daily effluent discharges and WQ measurement data are analyzed in the Nakdong river estuarine seadike. The contribution factor defined by the ratio of the water quantity range and WQ range shows that the PL pattern in this estuary is classified as the strongly flow(water quantity)-dominated situation. The estimated PL(EPL)s with respect to the increasing sampling periods, e.g., 2-days, 5-days, 7-days, and so on, show that the mean values of the EPLs remain nearly same, whereas the standard deviations of the EPLs have an obvious increasing trend. The PL values using the monthly-averaged water quantity and WQ measurement data could have approximately 100% estimation error in annual mean and $300\sim400%$ estimation errors in summer season because its confidence level is relatively low. It is recommended that the PL should be estimated using at least $10\sim20$ day interval data sets and also the water quantity(river discharges) and WQ should be measured at the intervals of at least 1 day interval and 5 to 7 days, respectively in summer.

• Journal of Korean Society for Geospatial Information Science
• /
• v.16 no.1
• /
• pp.23-32
• /
• 2008

According to recent frequent local flash flood due to climate change, the very short-term rainfall forecast using remotely sensed rainfall like radar is necessary to establish. This research is to evaluate the feasibility of GIS-based distributed model coupled with radar rainfall, which can express temporal and spatial distribution, for multipurpose dam operation during flood season. $Vflo^{TM}$ model was used as physically based distributed hydrologic model. The study area was Yongdam dam basin ($930\;km^2$) and the 3 storm events of local convective rainfall in August 2005, and the typhoon.Ewiniar.and.Bilis.collected from Jindo radar was adopted for runoff simulation. Distributed rainfall consistent with hydrologic model grid resolution was generated by using K-RainVieux, pre-processor program for radar rainfall. The local bias correction for original radar rainfall shows reasonable results of which the percent error from the gauge observation is less than 2% and the bias value is $0.886{\sim}0.908$. The parameters for the $Vflo^{TM}$ were estimated from basic GIS data such as DEM, land cover and soil map. As a result of the 3 events of multiple peak hydrographs, the bias of total accumulated runoff and peak flow is less than 20%, which can provide a reasonable base for building operational real-time short-term rainfall-runoff forecast system.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.3
• /
• pp.337-352
• /
• 2023

In general, Rainfall-Runoff model parameter set is optimized using the entire data to calculate unique parameter set. However, Korea has a large precipitation deviation according to the season, and it is expected to even worsen due to climate change. Therefore, the need for hydrological data considering seasonal characteristics. In this study, we conducted regional sensitivity analysis(RSA) using the conceptual Rainfall-Runoff model, GR4J aimed at the Soyanggang dam basin, and clustered combining the RSA results with hydrometeorological data using Self-Organizing map(SOM). In order to consider the climate characteristics in parameter estimation, the data was divided based on clustering, and a calibration approach of the Rainfall-Runoff model was developed by comparing the objective functions of the Global Optimization method. The performance of calibration was evaluated by statistical techniques. As a result, it was confirmed that the model performance during the Cold period(November~April) with a relatively low flow rate was improved. This is expected to improve the performance and predictability of the hydrological model for areas that have a large precipitation deviation such as Monsoon climate.

• Journal of the Korean earth science society
• /
• v.32 no.7
• /
• pp.770-783
• /
• 2011

In this study, we performed a downscaling of an ECHAM5 simulated dataset for the current and future climate produced under the Special Report on Emission Scenarios A1B (SRES A1B) by utilizing the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM). The current climate simulation was performed for the period 1980-2000 and the future climate run for the period 2040-2070 for the COordinated Regional climate Downscaling EXperiment (CORDEX)'s East Asia domain. The RSM is properly able to reproduce the climatological fields from the evaluation of the current climate simulation. Future climatological precipitation during the summer season is increased over the tropical Oceans, the maritime-continent, and Japan. In winter, on the other hand, precipitation is increased over the tropical Indian Ocean, the maritime-continents and the Western North Pacific, and decreased over the eastern tropical Indian Ocean. For the East Asia region few significant changes are detected in the precipitation climatological field. However, summer rainfall shows increasing trend after 2050 over the region. The future climate ground temperature shows a clear increasing trend in comparison with the current climate. In response to global warming, atmospheric warming is clearly detected, which strengthens the upper level trough.

• Solar Energy
• /
• v.13 no.2_3
• /
• pp.65-78
• /
• 1993

An overdose of fossil fuel for greenhouse heating causes not only the high cost and low quality of agricultural products, but also the environmental pollution of farm village. To solve these problems it is desirable to maximize the solar energy utilization for the heating of greenhouse in winter season. In this study phase change materials were selected to store solar energy concentratively for heating the greenhouse and their characteristics of thermal energy storage were analyzed. The results were summarized as follows. The organic $C_{28}H_{58}$, and the inorganic $CH_3COONa{\cdot}3H_2O\;and\;Na_2SO_4{\cdot}10H_2O$ were selected as low temperature latent heat storage materials. The equation of critical radius was derived to define the generating mechanism of the maximum latent heat of phase change materials. The melting point of $C_{28}H_{58}$ was $62^{\circ}C$, and the latent heat was $50.0{\sim}52.0kcal/kg$. The specific heat of liquid and solid phase was $0.54{\sim}0.69kcal/kg^{\circ}C$ and $0.57{\sim}0.75kcal/kg^{\circ}C$ respectively. The melting point of $CH_3COONa{\cdot}3H_2O$ was $61{\sim}62^{\circ}C$, the latent heat was $64.9{\sim}65.8$ kcal/kg and the specific heat of liquid and solid phase was respectively $0.83kcal/kg^{\circ}C$ and $0.51{\sim}0.52kcal/kg^{\circ}C$. The melting point of $Na_2SO_4{\cdot}10H_2O$ was $30{\sim}30.9^{\circ}C$, the latent heat was 53.0 kcal/kg and the specific heat of liquid and solid phase was respectively $0.78{\sim}0.89kcal/kg^{\circ}C$ and $0.50{\sim}0.7kcal/kg^{\circ}C$ When the urea of 21.85% was added to control the melting point of $Na_2SO_4{\cdot}10H_2O$ and the phase change cycles were repeated from 0 to 600, the melting point was $16.7{\sim}16.0^{\circ}C$ and the latent heat was $36.0{\sim}28.0kcal/kg^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.8 no.2
• /
• pp.90-100
• /
• 1975

The estimation of the pre-processing condition of oyster is of great importance for distributors and processors. This study was attempted to establish the basic data for evaluating the processing suitability of oyster, which is the most important shellfish for domestic use and export. The data were analysed by measuring the condition index, chemical composition and heavy metal content of oysters. In order to eliminate the manual work that has to be done on a tightly closed oyster shell and avoid shrinkage in the oyster meat which is attendant on the steaming process, chemical means to open oyster were examined. finding the method of pretreatment of polyphosphate for frozen oysters were attempted to improve the product quality. The prevention of undesirable color change of the canned oyster meat is another problem to solve. The important results are as follows : 1. The ratio of meat volume and meat weight to the holding capacity by shells may be useful as an index to measure the condition index of oysters. 2. As a whole, monthly changes of moisture and fat content in oysters were reversely correlated. Protein content slightly decreased from April and rapidly decreased in July, and again rapidly increased in August but from September to November decreased slightly. In April, the content of glycogen was 4 percent. From this period to September, glycogen was rapidly decreased. From July to September, it was only 0. 7 to 1 percent but increased from October. There were little seasonal changes in pH value. The pH value of oyster meat was 6.0 to 6.2. The crude ash content was slightly decreased from June to August. 3. The range of monthly change of heavy metal content are as follows: Total mercury was 0 to 0.019 ppm, cadmium was 0.026 to 0.053 ppm, copper was 0.111 to 0.594 ppm, and lead_was 0.061 to 0.581 ppm. 4. By the results of condition index, chemical composition and heavy metal content of oysters, the suitable harvest season as raw materials for processing was the end of December to the end of May of next year. 5. The pretreatment of 10 percent polyphosphate in 5 percent salt solution of oyster meat appeared effective to reduce thawing drip during cold storage. 6. The pretreatment of $Na_2EDTA$ and BHA did not show the color prevention effect to the canned oyster meat during storage. 7. Magnesium chloride affected to open the valves of oysters.

• Journal of the Korean earth science society
• /
• v.39 no.5
• /
• pp.419-435
• /
• 2018

The purpose of this study is to understand meteorological and climatological factors that have influence on the garlic product in Seosan and Taean, and to analyze the economic value according to the use of climatical information data for garlic farmers. The climatological characteristics and trends in this area are analyzed using the meteorological data at the Seosan local meteorological agency from 1984 to 2013, the national statistical data for the product of garlic from 1989 to 2013, and the scenario data for climate change (RCP 4.5 and 8.5) for the period from 2001 to 2100. The results are as follows. First, the condition of lower temperature for garlic growth in winter season is satisfied with the mean air temperature. The wind speed are lower and stronger in Seosan and Taean than other garlic area. The suitable condition for the growth of northern type of garlic shows the decreasing trend in the accumulated precipitation in May. However, the area of growing the northern type garlic in the future is likely diminished because mean air temperature, accumulated precipitation, and mean wind speed are strong in the harvest time of garlic. Second, the seedtime of the northern and southern type of garlic using climate change scenarios (RCP 4.5, 8.5) in Seosan and Taean is getting late as time passes. and the harvest time gets faster, which indicates s that the period of garlic cultivation becomes shorter from 50 days to around 90 in the next 100 years. Third, the beginning days of white rot and delia platura of garlic are estimated by applying to the meteorological algorithm using mean air temperature and soil humidity. Especially, the beginning day of white rot garlic is shown to be faster according to the scenarios of RCP 4.5 and RCP 8.5. Fourth, the product of garlic (kg/10a) shows a high correlation with the minimum air temperature of a wintering time, the mean wind speed of a wintering time, the accumulated precipitation of a corpulent time, and the mean relative humidity of corpulent time of garlic. On the other hand, the analysis of garlic product when using the meteorological information data in cultivating garlic in Seosan and Taean reveals that the economic value increases up to 9% in total.

• Korean Journal of Remote Sensing
• /
• v.14 no.3
• /
• pp.296-306
• /
• 1998

Airborne MSS data is regarded as a potentially effective data source for the measurement of water quality and for the environmental change of water bodies. In this study, we measured the radiance reflectance by using multi-spectral image of low resolution camera(LRC) which will be reached in the multi-purpose satellite(KOMPSAT) to use the data in analyzing water pollution. We also investigated the possibility of extraction of water quality factors in water bodies by using high resolution remote sensing data such as Airborne MSS. Especially, we tried to extract environmental factors related with eutrophication such as chlorophyll-a, suspended sediments and turbidity, and also tried to develop the process technique and the radiance feature of reflectance related with eutrophication. Although it was difficult to explicitly correlate Airborne MSS data with water quality factors due to the insufficient number of ground truth data. The results were summarized as follows: First, the spectrum of sun's rays which reaches the surface of the earth was consistent with visible bands of 0.4${\mu}{\textrm}{m}$~0.7${\mu}{\textrm}{m}$ and about 50% of total quantity of radiation could be found. The spectrum was reached highest at around 0.5${\mu}{\textrm}{m}$ of green spectral band in visible bands. Second, as a result of the radiance reflectance Chlorophyll-a represented high mainly around 0.52${\mu}{\textrm}{m}$ of green spectral band, and suspended sediments and turbidity represented high at 0.8${\mu}{\textrm}{m}$ and at 0.57${\mu}{\textrm}{m}$, respectively. Finally, as a result of the water quality analysis by using Airborne MSS, Chlorophyll-a could have a distribution image after carrying out ratio of B3 and B5 to B7. Band 7 was useful for making the distribution image of suspended sediments. When we carried out PCA, suspended sediments and turbidity had distributions at PC 1 and PC 4 which are similar to the ground data. Above results can be changed according to the change of season and time. Therefore, in order to analyze the environmental factors of water quality by using LRC data more exactly, we need to investigate the ground data and the radiance feature of reflectance of water bodies constantly. For further studies, we will constantly analyze the radiance feature of the surface of water in wafter bodies by measuring the on-the-spot radiance reflectance and using low resolution satellite image(SeaWiFS). We will also gather the data of water quality analysis in water bodies and analyze the pattern of water pollution.