• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.1
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• pp.13-21
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• 2008

Water losses in irrigation canals are mainly estimated as the sum of conveyance and delivery water loss. The losses occur via the evaporation, infiltration, gate operation and water distribution processing. Recently, the study regarding these water losses are not satisfactory enough, also delivery water loss has not been mainly considered on field design. The objective of this study is to investigate and analyze the volume of water loss in irrigation canals considering condition of actual farm land. A field measurement was performed at four research sites, which are managed by Korea Rural Community & Agriculture Corporation, to evaluate conveyance and delivery water loss for 2 years. The measurement was performed by canal type, size and designed flow using the inflow-outflow method at a major points such as start and end of each canal, derivation point of canal and inlet of paddy fields. Results of this study showed that water loss ratio in lateral canals was bigger than that of main canal unlike current design standard and the loss decrease as flow increase. The total of water loss ratio including conveyance and delivery water loss in several irrigation canals ranged between 33.25 and 45.0%.

• Journal of Korea Water Resources Association
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• v.45 no.6
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• pp.597-606
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• 2012

With the availability of multi-scale hydrologic data in public domain depending on DEM size, there is a need for a modeling framework that is capable of using these data to simulate hydrologic processes at multiple scales for different topographic and climate conditions for distributed hydrologic model. To address this need, an object-oriented approach, called Geographic and Hydrologic Information System Modeling Objects (GHISMO), is developed. Main hydrologic approaches in GHISMO are storage-release for direct runoff and SCS curve number method for infiltration part. This paper presents conceptual and structural framework of storage-release concept including its application to two watersheds will be presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1167-1172
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• 2004

Recently, runoff characteristics of urban area are changing because of the increase of impervious area by rapid increasing of population and industrialization, urbanization. It needs to extract the accurate topological and hydrological parameters of watersheds in order to manage water resource efficiently. In this paper, rainfall-runoff analysis in An-Yang stream basin was made using GIS(Geographic Information System) and XP-SWMM(Export Stormwater and Wastewater Management Model). The basin was divided into 13 sub-basins using GIS. The area, slope, width of each subcatchment and length, slop of each stream reach were acquired from topographic maps, and imperviousness rate, land use types, infiltration capacities of each subcatchment from land use maps and soil maps using GIS. We gave th runoff management method of urbanization area us ing XP-SWMM.

• Journal of Soil and Groundwater Environment
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• v.15 no.6
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• pp.1-8
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• 2010

The groundwater level distribution and characteristics of responses to rainfall were examined in the Haean basin of Yangu that has a single stream exit to the east. The groundwater levels showed a circular or elliptical distribution converging the center of the basin with different hydraulic gradients in the north and south regions. The waterlevel elevations exhibited a perfect correlation with topographic elevation ($r^2=0.99$) while the depth to water showed a rather weak correlation ($r^2=0.49$). The water table fluctuation (WTF) method yielded recharge ratios of 6.1~12.65% ($S_y=0.02$) and 15.2~28.5% ($S_y=0.05$). The waterlevels of HG3 well, which is much proximal to a stream, were weakly auto-correlated but they were highly sensitive to direct infiltration from the rainfall event. The shorter regulation times of the HG3 represented a quicker dissipation of the input stress (rainfall).

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.591-600
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• 1997

Al2O3/Al composites were produced by displacement reaction method, which was carried out by immersing the sintered silica preform, which was prepared from fused silica powder, in molten aluminum. Because the molten aluminum did not penetrate into the silica preform with higher than 20% of porosity when the displacement reaction was accomplished at 100$0^{\circ}C$ for 10 hours in air atmosphere, the optimum range of sintering temperature of silica preform was from 135$0^{\circ}C$ to 140$0^{\circ}C$. The microstructure of this Al2O3/Al composites showed three-dimentionally co-continuous alumina, which provides wear resistance and high stiffness, and aluminium which acts as a toughnening phase. The grain size of the alumina in composites did not change with the particle size of the silica preform. The exact shape of the preform was retained and a net-shaped composite was produced. The representative Al2O3/Al composite prepared in this study showed 3.30mg/㎤ of bulk density, 350-430 MPa of flexural strength, 7.0 MPa.m1/2 of fracture toughness, and good machinability.

• Korean Journal of Bronchoesophagology
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• v.17 no.1
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• pp.23-28
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• 2011

Diagnosis of early esophageal cancer has become more frequent as a result of improved endoscopic technology, surveillance programmes, and increasing experience and awareness on the part of endoscopists. In early esophageal cancer, squamous cell carcinoma and early adenocarcinoma must be managed differently because they have different origins, pathogenesis. and clinical characteristics. The current treatment options vary widely, from extended resection with lymphadenectomy to endoscopic mucosal resection (EMR) or ablation. None of these treatment options can be recommended universally. Instead, an individualized strategy should be based on the depth of tumor infiltration into the mucosa or submucosa, the presence or absence of lymph node metastases, the multicentricity of tumor growth, the length of the segment of intestinal metaplasia, and comorbidities of the patient. EMR has become increasingly important, both as a diagnostic tool for the staging of esophageal carcinomas and as a method of carrying out definitive treatment when the cancer meets certain criteria in which the risk of lymph-node metastasis is negligible. EMR may be sufficient in a subset of patients who have m1 or m2 squamous cell carcinoma and in patients who have isolated foci of high-grade intraepithelial neoplasia or mucosal cancer.

• Korean Journal of Veterinary Research
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• v.44 no.3
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• pp.329-334
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• 2004

Ischemia/reperfusion(I/R) injury of the rat testis causes germ cell death and infiltration of inflammatory cells. To investigate the mechanism of germ cell death in torsion of the rat testis, apoptosis and macrophage activation were studied using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling(TUNEL) method and immunohistochemistry in the testes of Sprague-Dawley rats subjected to 1.5 h of ischemia, followed by 0, 1, 3, 6, 12, 24, 48 and 96 h of reperfusion. Apoptotic, TUNEL-positive cells were found at the base of the seminiferous epithelia after I/R. TUNEL-positive cells were significantly increased 6 h after repair of the torsion, and there was a significant peak in apoptosis 24 h after reperfusion, as compared with normal or sham-operated controls. In contrast, histological evidence of germ cell necrosis in the seminiferous tubules was first visible 24 h after reperfusion. In the testis of sham-operated rats, ED2-positive resident macrophages were found diffusely in the interstitial space, while ED1-positive monocyte-like macrophages were rarely found. After I/R, ED1-positive cells were significantly increased beginning 12 h after reperfusion, while ED2-positive immunoreactivity did not change during the experimental period. Together, the results of this study confirmed that increased numbers of ED1-positive macrophages, but not resident ED2-positive macrophages, infiltrated the interstitial space surrounding damaged tubules and induced germcell death.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1033-1039
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• 2004

The methodology developed by Soil Conservation Service for determination of runoff value from precipitation is applied to estimate the precipitation recharge in the Pyungchang river basin. Two small areas of the basin are selected for this study. The CN values are determined by considering the type of soil, soil cover and land use with the digital map of 1:25,000. Forest covers more than $94{\%}$ of the study area.. The CN values for the study area vary between 47 in the forest area and 94 in the bare soil under AMC 2 condition. The precipitation recharge rate is calculated for the year when the precipitation data is available since 1990. To obtain the infiltration rate, the index of CN and five day antecedent moisture conditions are applied to each precipitation event during the study period. As a result of estimation, the value of precipitation recharge ratio in the study area vary between $15.2{\%}\;and\;35.7{\%}$ for the total precipitation of the year. The average annual precipitation recharge rate is $26.4{\%}\;and\;26.8{\%}$, meaning 377.9mm/year and 397.5mm/year in each basin.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.11-19
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• 2011

PADDIMOD2 was deloped to estimate nonpoint source pollution from paddy rice fields. The PADDIMOD2 was enhanced to estimate runoff and pollutant load during non-growing as well as growing season and to be easily used for public by development of Excel based system. Nutrient concentration and hydrology were based on Dirac delta function and continuous source function, and tank model for growing season and Event Mean Concentrations (EMCs) and SCS-Curve Number method for non-growing season. The PADDIMOD2 consists of three main component (input data, parameters data, and output data) by including eight Excel spread sheets. As a result of model application, total precipitation and irrigation were 1,051.7 mm and 439.2 mm, respectivley and surface runoff and water loss including infiltration and evapotranspiration were 463.0 mm and 947.9 mm, respectively. Annual nutrient loadings of T-N and T-P from study area were 6.7 kg/$km^2$/day and 0.5 kg/$km^2$/day, respectively. Development of PADDIMOD2 was focused on minimizing input data and maximizing user friendly system and is expected to be useful tool to evaluate various non-structure BMPs and estimate unit load from paddy rice fields for application at Korean TMDL.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.378-383
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• 2013

Continuous fiber-reinforced ceramic matrix composites (CFCCs) have a complex distribution of porosity, consisting of interfiber micro pores and interbundle/interply macro pores. Owing to the complex geometry of the pores and fiber architecture, it is difficult to obtain representative microstructural features throughout the specimen volume with conventional, destructive ceramographic approaches. In this study, we introduce X-ray computed microtomography (X-ray ${\mu}CT$) to nondestructively analyze the microstructures of disk shaped and tubular $SiC_f$/SiC composites fabricated by the chemical vapor infiltration (CVI) method. The disk specimen made by stacking plain-woven SiC fabrics exhibited periodic, large fluctuation of porosity in the stacking direction but much less variation of porosity perpendicular to the fabric planes. The X-ray ${\mu}CT$ evaluation of the microstructure was also effectively utilized to improve the fabrication process of the triple-layered tubular SiC composite.