• Korean Journal of Agricultural Science
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• v.26 no.2
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• pp.77-93
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• 1999

This study is aiming at identifying the foreward and backward lingkage effects of the farm land base development project. Korean Government has continuously carried out farmland base development projets including the integrated agricultural development projects. large and medium scale irrigation projects and the comprehensive development of the four big river basin including tidal land reclamation and estuary dam construction for the all weather farming since 1962. the starting year of the five year economic development plans. Consequently the irrigation rate of paddy fields in Korea reached to 75% in 1998 and to escalate the irrigation rate, the Government had procured heavy investment fund from IBRD. IMF and OECF etc. To cope with the agricultural problems like trade liberalization in accordance with WTO policy, the government has tried to solve such problems as new farmland base development policy, preservation of the farmland and expansion of farmland to meet self-sufficiency of foods in the future. Especially, farmland base development projects have been challanged to environmental and ecological problems in evaluating economic benefits and costs where the value of non-market goods have not been included in those. Up to data, in evaluating benefits and costs of the projects, farmland base development projects have been confined to direct incremental value of farm products and it's related costs. Therefore the projects'efficiency as a decision making criteria has shown the low level of economic efficiencies. In estimating economic efficiencies including Leontiefs input-output analysis of the projects could not be founded in Korea at present. Accordingly this study is aimed at achieving and identifying the following objectives. (1) To identify the problems related to the financial supports of the Government in implementing the proposed projects. (2) To estimated backward and foreward linkage effects of the proposed project from the view point of national economy as a whole. To achieve the objectives, Hwangrak benefited area with reservoir which is located in Seosan-haemi Disticts, Chungnam Province were selected as a case study. The main results of the study are summarized as follows : a. The present value of investment and O & M cost were amounted to 3,510million won and the present value of the value added in related industries was estimated at 5.913million won for the period of economic life of 70 years. b. The total discounted value of farm products in the concerned industries derived by the project was estimated at 10,495million won and the foreward and backward linkage effects of the project were amounted to 6,760 and 5,126million won respectively. c. The total number of employment opportunities derived from the related industries for the period of project life were 3,136 man/year. d. Farmland base development projects were showed that the backward linkage effects estimated by index of the sensitivity dispersion were larger than the forward linkage effect estimated by index of the power of dispersion. On the other hand, the forward linkage effect of rice production value during project life was larger than the backward linkage effect e. The rate of creation of new job opportunity by means of implementing civil engineering works were shown high in itself rather than any other fields. and the linkage effects of production of the project investment were mainly derived from the metal and non-metal fields. f. According to the industrial linkage effect analysis, farmland base development projects were identified economically feasible from the view point of national economy as a whole even though the economic efficiencies of the project was outstandingly decreased owing to delaying construction period and increasing project costs.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.535-544
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• 2021

Agricultural water occupies 48% of water demand, and management of agricultural reservoirs is essential for water resources management within agricultural basins. For more efficient use of agricultural water, monitoring the distribution of water resources in agricultural reservoirs and agricultural basins is required. Therefore, in this study, three threshold determination methods (i.e., fixed threshold, Otsu threshold, Kittler-Illingworth (KI) threshold) were compared to detect terrestrial water bodies using Sentinel-1 images for 3 years from 2018 to 2020. The purpose of this study was to evaluate methods for determining threshold values to more accurately estimate the reservoir area. In addition, by analyzing the relationship between the water surface and water storage at the Edong, Gosam, and Giheung reservoirs, water storage based on the SAR image was estimated and validated with observations. The thresholding method for detecting a waterbody was found to be the most accurate in the case of the KI threshold, and the water storage estimated by the KI threshold indicated a very high agreement (r = 0.9235, KGE' = 0.8691). Although the seasonal error characteristics were not observed, the problem of underestimation at high water levels may occur; the relationship between the water surface and the water storage could change rapidly. Therefore, it is necessary to understand the relationship between the water surface area and water storage through ground observation data for a more accurate estimation of water storage. If the use of SAR data through water resources satellites becomes possible in the future, based on the results of this study, it is judged that it will be beneficial for monitoring water storage and managing drought.

• Korean Journal of Heritage: History & Science
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• v.51 no.3
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• pp.72-87
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• 2018

This study highlights a drainage gate and a ditch, which existed around the whole area of the western shore of Wolji Pond(月池) and focuses on a possible connection between the drainage facility on the western shore and the historical drainage system of Wolji Pond. Specifically, it primarily considered locations and the form of a drainage gate, the relationship between northwestern ditch of Wolji Pond and the drainage gate, and the establishment period and the character of the drainage facility on the western shore. The drainage gate found in excavation in 1975 is determined as the same facility as Surakgu(水落口) recorded on an actual measurement drawing, 1922. Therefore, it is highly probable that there were already the drainage facility in the western shore of Wolji Pond before the 1920s. The drainage gate constructed by processing rectangular stones has four drainage holes for controlling water level. The way of the drainage through the drainage holes is the same as that of the northern shore of Wolji Pond. From a cadastral map drawn in 1913, it is found that the ditch existed in northwest of Wolji Pond. The ditch was proximate to the drainage gate and shared the same axes. Hence, the ditch and the drainage gate are determined as a organic facility connected to the drainage system of Wolji Pond. In particular, the ditch existed in northwest of Wolji Pond is the basis for judging that the drainage facility in the western shore were established before the 1910s. Water flowed in through drainage holes of the drainage gate is drained into the northwest of Wolji Pond, through the ditch. The establishment period and the intention of the drainage facility on the western shore can be interpreted in two aspects. First, they might be 'a agricultural irrigation facility in the Joseon era', given that Wolji Pond was recorded as a agricultural reservoir, and that the whole northwestern area of Wolji Pond was used as farm land areas. Second, they might be 'a drainage facility for controlling the water level in creating Wolji Pond', given that the drainage gate was annexed to the lower shore forming the waterline of Wolji Pond, and that the hight of drainage holes on top of the drainage gate was similar to the full water level of Wolji Pond. Considering the related grounds and circumstance, the latter possibility is high.

• Korean Journal of Ecology and Environment
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• v.55 no.3
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• pp.201-211
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• 2022

The macroinvertebrate community in the Singal reservoir, Yedang and Juam lake was investigated three times from April 2021 to October 2021. Each lake was investigated by dividing it into inflow, middle-flow, and outflow. Additionally, sampling was conducted again by dividing it into the edge and center parts at each inflow, middle-flow, and outflow. Eight families of benthic macroinvertebrates were collected except for chironomids in the sampling sites. Dominant macroinvertebrates were investigated as chironomids, and Tubificidae was sub-dominant organisms. The density of macroinvertebrate community was higher in the edge area than in the center bottom of the lakes. The density of chironomids was low when the water level was high but was high when the water level was low. In the edge area of the middle-flow in Singal reservoir, the density of chironomids was 1,208 ind. m^-2 in April when the water level was high, but it increased to 1,401 ind. m^-2 in July when the water level was low. Similarly, the density of chironomids at the outflow of Yedang lake was high (1,990 ind. m^-2) in July when the water level was low. The density of chironomids also decreased along with the increasing water level at all edge areas of Juam lake. These results indicated that it will be necessary to consider the water level when studying macroinvertebrate communities in the lake.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.245-265
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• 2019

Biotope, which represents the characteristic habitats of living organisms, need to be identified as essential for the efficient creation and sustainable management of urban ecosystems. This study was carried out to provide the basic information for ecological urban planning by analyzing types and attributes of the biotop established throughout the whole area of the Pohang city, a representative industrial city in Korea. The biotop established in Pohang city is composed of 12 types including forests (coniferous, deciduous, and mixed forests), agricultural fields (rice paddy and upland field), green facilities, river, reservoir, bare ground, residential area, public facilities, commercial area, industrial area, roads, and schools. As a result of analyzing the properties according to biotop types, industrial, commercial and residential areas, which represent urban areas, was dominated by introduced vegetation. Moreover the introduced vegetation is usually composed of exotic plants or modified forms for landscape architecture and horticulture rather than native plants, which reflects ecological property of both region and site. As the distance from the urban center increases, the agricultural field showed a form of typical farmland, whereas the closer it is, the more form of greenhouse farming. Natural green spaces were divided into riparian vegetation established along the stream and forest vegetation. Forest vegetation is consisted of secondary forests (seven communities) and plantations (three communities). The urban landscape of Pohang city is dominated by the industrial area. Among them, the steel industry, which occurs large amounts of heat pollution and carbon dioxide, occupies a large proportion. On the other hand, green space is very insufficient in quantity and inferior in quality. This study proposed several restoration plans and further, a green network, which ties the existing green spaces and the green space to be restored as a strategy to improve the environmental quality in this area.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.313-321
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• 2012

To analyze the bird communities by the land use type, we surveyed 43 plots in Siheung City, Korea from Mar. 2009 to Feb. 2010 and classified the community by TWINSPAN and DCA. Classification result by TWINSPAN was classified into 4 communities. In the first division, waterbirds, such as spot-billed duck(Anas poecilorhyncha) and great egret(Egretta alba) operated as the differential species. In the second and third division, little grebe(Tachybaptus ruficollis) and eurasian sparrow(Passer montanus) were operated as the differential species. The relationship between land use types and classified bird communities, all plots of community I were located in the forest. Community II plots were contained all urban and several semi-natural land use types. Community III contains stream and rice paddy. Plots in the reservoir were classified community IV. The stream and rice paddy were classified into different communities, which were colsely related with the size of wetland paddy. Community III had the highest species diversity index and community II had lowest. Community III also had the highest maximum species diversity index and evenness index. The result of this study, small stream and small rice paddy located within the city have insignificant characteristics as the habitat for birds. Management size of semi-natural land use for wildbird habitat in the urban area should be considered for showing their habitat characteristics. If the classification of biotope type based on the scale of rice paddy and urban park and the type of landuse type in the riverside then we should be consider the standard of minium area.

• Journal of fish pathology
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• v.20 no.3
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• pp.201-209
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• 2007

Viral hemorrhagic septicemia (VHS) is one of the most serious viral disease of farmed rainbow trout and some marine fishes in Europe and North America. It has been reported in various marine fish species of Asian countries and induced cause mass mortality in Japanese flounder (Paralichthys olivaceus) culturing in Korea. The aims of this study were to monitor VHSV in wild marine fishes and to give critical information for controling the disease through prophylactic methods. Prevalence of the viral disease, geological distribution and reservoir of the virus were investigated using wild marine fishes captured in southern coast and east china sea for two years. (Reverse Transcriptase Polymerase Chain Reaction) RT-PCR results showed that VHSV were detected in 17 (10.6%) out of 160 fish. G gene sequences of viral strains isolated in this study were closely related to that of a reference strain, KVHS01-1, belonging to VHSV genotype Ⅰ. The results suggest that some of wild marine fishes are VHSV carriers and may spread the pathogen directly to fish farmed in coastal area.

• Journal of fish pathology
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• v.20 no.3
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• pp.211-220
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• 2007

Red sea bream iridovirus disease (RSIVD) cause massive economic losses in marine aquaculture industry in Korea. The causative agent of this disease (RSIV) infects a wide range of fish species. The aims of this study were to monitor RSIV in wild marine fishes and to give critical information for controling the disease through prophylactic methods. Prevalence of the viral disease, geological distribution and reservoir of the virus were investigated using wild marine fishes captured in southern coast and east china sea for two years. (Polymerase Chain Reaction) PCR results showed that RSIV were detected in 39 (24.3%) out of 160 fish. MCP gene sequences of viral strains isolated in this study were closely related to that of a reference strain, red seabream-K, belonging to Megalocytivirus subgroup Ⅲ. The results suggest that some of wild marine fishes are RSIV carriers and may spread the pathogen directly to fish farmed in coastal area.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.100-101
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• 2004

Many researches in Korea have been performed to understand the pollution of stream waters by acid mine drainage. However, few studies have been conducted regarding the effect of particulate and colloidal fractions on the transport of trace metals. To estimate harmful effects of trace metals, it is important to evaluate the particulate and colloidal metals as well as dissolved metals, because particulate and colloidal fractions of trace metals play an important role in transport of trace metals and may adversely affect habitats and organisms in riverine system. Colloids are solids with effective diameters in size range from 0.001 $\mu$m to 1 $\mu$m. According to Jone et al. (1974), metals in surface water, like Al, Fe, and Mn, require filtration with pore-size membranes smaller than 0.45 $\mu$m to define dissolved concentrations. The main objective of this study is to understand the effects of particulate, colloidal, and truly dissolved fractions on the transport and fate of trace metals in acid mine drainage. This study was conducted for the Onjeong creek in the Uljin mine area. Sampling was carried out in 13 sites, spatially covering the area from mine dumps to the downstream Onjeong reservoir. To examine the metal partitioning between particulate, colloidal, and truly dissolved fraction, we used successive filtration techniques consisting of conventional method (using 0.45 $\mu$m membranes) and tangential-flow ultrafiltration (using 0.001 $\mu$mm membranes). Ultrafiltration may seperate much smaller particles from aqueous phase (Josephson, 1984; Hernandez and Stallard, 1988). The analysis of metals were performed by inductively coupled plasma - atomic emission spectrometer (ICP-AES: model Perkin Elmer OPTIMA3000XL). Anions such as SO$_4$, Cl and NO$_3$ were measured with ion chromatograph (IC: model Dionex 120). Sample analysis is still in progress. The preliminary data show that the studied creek is severely polluted by Al, Fe, Mn, Pb and Zn. Toward upstream sites with relatively lower pH, less than 50% of Al and Fe occur in the sorbed form on particles or colloids, whereas more than 80% of Al and Fe occur in the sorbed form in downstream sites or tributaries with relatively higher pH. Less than 30% of Zn is present in particle or colloidal forms in the whole range of creek. Truly dissolved fraction of trace metals is negatively correlated with pH. The Kd values for Al, Fe and Zn consistently increase with increasing pH and decrease with increasing particle concentration.

• Journal of Wetlands Research
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• v.15 no.2
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• pp.223-231
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• 2013

Excessive precipitation, drought, heat waves, strong typhoons and rising sea levels are just some of the common indicators of climate change. In the Philippines, excessive precipitation never failed to devastate and drown the streets of Metro Manila, a highly urbanized and flood-prone area; such problems are expected to occur frequently. Moreover, the water supply of Metro Manila is dependent only to Angat Reservoir. Rainwater harvesting can serve as an alternative source of raw water and it can mitigate the effects of flooding. The harvested rainwater can be used for: potable consumption if filtered and disinfected; and non-potable consumptions (e.g., irrigation, flushing toilets, carwash, gardening, etc.) if used untreated. The rainfall data were gathered from all 5 rainfall stations located in Metro Manila namely: Science Garden, Port Area, Polo, Nangka and Napindan rain gauge stations. To be able to determine the potential volume of rainwater harvested and the potentiality of rainwater harvesting system as an alternate source of raw water; in this study, three different climatic conditions were considered, the dry, median and wet rainfall years. The frequent occurrence of cyclonic events in the Philippines brought significant amount of rainwater that causes flooding in the highly urbanized region of Metro Manila. Based from the results of this study, the utilization of rainwater harvesting system can serve as an alternative source of non-potable water for the community; and could also reduce the amount of surface runoff that could result to extreme flooding.