• Ocean and Polar Research
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• v.30 no.1
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• pp.33-46
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• 2008

In order to investigate seasonal variations of the physical environments in the region of Jinhae Bay-Nakdongpo, we carried out hydrographic surveys from November 2000 to November 2001. Horizontal and vertical distribution of salinity and temperature shows large seasonal variations. Water column is well mixed in winter and stratified in summer. Low-salinity water is distributed in the form of patches because of the drainage control at the Nakdong River. Seasonal variations in the sea near Gadeok-Sudo are affected by topography, river discharge and tidal current. Currents have been measured using a bottom mounted ADCP and DCM12 between November 2000 and August 2001 in the Gadeok-Sudo. The current in the Gadeok-Sudo shows a distinct two-layer structure with reversed current. Low-pass filtered time series of wind, sea elevation and current are coherent for the period of 1-2 days and are attributed to Ekman-like dynamics. Spatial and temporal circulation pattern shows a slight different. The subtidal current in Jinhae Bay goes northward, however is reversed in the Gadeok-Sudo mouth.

• Economic and Environmental Geology
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• v.33 no.4
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• pp.261-271
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• 2000

In order to evaluate the environmental impact of U anormaly in the drainage system around the Shinbo talc mine area, U contents, their distribution patterns, bioaccumulation and a-radioactivity in stream water, stream sediments and aquatic organisms were investigated. The U contents of stream water attenuated with increasing distance from the mine area. The same attenuation pattern is shown in stream sediments from mine to 0.75 km downstream, although these contain highly enriched U contents (24~83 mg/kg) comparing with the international average concentration of surface soils (0.79~11 mg/kg). However, U content increases abruptly in sediment at 1.5 km downstream, probably due to detrital migration and rediposition of U enriched sediments. Futhermore, enriched U in downstream sediments occur in high proportions of carbonate and Fe-Mn oxide bounded forms, which show high potential of a secondary pollution source. For aquatic organisms, bio accumulation degree of U are in the order: aquatic larvae>black snail>mountain frog>crawfish. Cultured trout by the U enrich groundwater (387 ${\mu}g$/l) shows U accumulation in the part of branchia (CRs 5.25) and bones (CRs 11.2) but not in flesh (CRs 0.03). Total a-radioactivity have been measured in the level as 0.47 nCi/l for groundwater, 2.94~18 nCi/kg${\cdot}$DW for organisms and 93~328 nCi/kg${\cdot}$DW for sediments.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2011.11a
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• pp.7-10
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• 2011

The semi-arid and arid regions comprise almost 40 percent of the world's land surface. The low and erratic precipitation pattern is the single most significant contributor for limiting crop production in such regions where rainfall is the source for surface, soil and ground water. In a changing climate, the semi-arid and arid regions would increasingly face the challenge of water scarcity. According to the relevant literature; under the assumption of a doubling of the current atmospheric CO2 concentration, irrigation demand was estimated to increase for wheat and to decrease for second crop maize in a Mediterranean environment of Turkey in the 2070s. Crop evapotranspiration would decrease due to stomata closure. Reference evapotranspiration and potential soil evaporation were projected to increase by 8.0 and 7.3%, respectively, whereas actual soil evaporation was predicted to decrease by 16.5%. Drainage losses below 90 cm soil depth were found to decrease mainly due to lesser rainfall amount in the future.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.576-582
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• 2013

Typical highway infrastructure systems include roadway pavement, drainage systems, tunneling, and other hardware components such as guardrails, traffic signs, and lighting. Tunnels in a highway system have provided significant advantages to overcoming various natural challenges including crossing underneath bodies of water or through mountainous areas. While only a few tunnel failure cases have been reported, the failure rate is likely to increase as these assets age and because agencies have not emphasized tunneling asset management. A tunnel system undergoes a deterioration life cycle pattern that is similar to other infrastructure systems. There are very few agencies in the United States implementing comprehensive tunnel asset management programs. While current tunnel asset management programs focus on inspection, maintenance, and operation safety, there is an increasing need for the development of a comprehensive life cycle tunnel asset management program. This paper describes a conceptual framework for a comprehensive tunnel asset management program. The framework consists of three basic phases including a strategic plan, a tactical plan, and an operational plan to provide better information to the decision makers. The strategic plan is a basic long term approach of tunnel asset management. The tactical plan determines specific objectives and the operational plan actually applies asset management objectives in practice. The information includes operational condition, structural condition, efficiency of the system, emergency response, and life cycle cost analysis for tunnel capital improvement project planning.

• Ecology and Resilient Infrastructure
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• v.8 no.4
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• pp.223-232
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• 2021

In general, stormwater flows to the road surface, especially in urban areas, and it is discharged through the drainage grate inlets on roads. The appropriate evaluation of the road drainage capacity is essential not only in the design of roads and inlets but also in the design of sewer systems. However, the method of road surface flow analysis that reflects the topographical and hydraulic conditions might not be fully developed. Therefore, the enhanced method of road surface flow analysis should be presented by investigating the existing analysis method such as the flow analysis module (uniform; varied) and the flow travel time (critical; fixed). In this study, the algorithm based on varied and uniform flow analysis was developed to analyze the flow pattern of road surface. The numerical analysis applied the uniform and varied flow analysis module and travel time as parameters were conducted to estimate the characteristics of rainfall-runoff in various road conditions using the developed algorithm. The width of the road (two-lane (6 m)) and the slope of the road (longitudinal slope of road 1 - 10%, transverse slope of road 2%, and transverse slope of gutter 2 - 10%) was considered. In addition, the flow of the road surface is collected from the gutter along the road slope and drained through the gutter in the downstream part, and the width of the gutter was selected to be 0.5 m. The simulation results were revealed that the runoff characteristics were affected by the road slope conditions, and it was found that the varied flow analysis module adequately reflected the gutter flow which is changed along the downstream caused by collecting of road surface flow at the gutter. The varied flow analysis module simulated 11.80% longer flow travel time on average (max. 23.66%) and 4.73% larger total road surface discharge on average (max. 9.50%) than the uniform flow analysis module. In order to accurately estimate the amount of runoff from the road, it was appropriate to perform flow analysis by applying the critical duration and the varied flow analysis module. The developed algorithm was expected to be able to be used in the design of road drainage because it was accurately simulated the runoff characteristics on the road surface.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.309-315
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• 2009

Maintenance of adequate soil water content during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement for precision irrigation would allow efficient supply of water to crops, thereby resulting in minimization of water drainage and contamination of ground water. This research reports on the characterization of spatial and temporal variations in water contents through three different textured soils, such as loam, sandy loam, and loamy sand, when water is applied on the soil surface using an one-line drip irrigation system and the soils are dried after the irrigation stops, respectively. Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30cm depths. Spatial variability in water content for each soil type was strongly influenced by soil textural class. There were big differences in wetting pattern and the rate of downward movement between loam and sandy loam soils, showing that the loam soil had a wider wetting pattern and a slower rate of downward movement than did the sandy loam soil. The wetting pattern in loamy sand soil was not apparent due to a low variability in water content (< 10%) by a lower-water holding capacity as compared to those measured in the loam and sandy loam soils, implying that the rate of water drainage below a depth of 30cm was high. When soils were dried, there were highly exponential relationships between water content and time elapsed after irrigation stops ($r^2$${\geq}$0.98). It was estimated that equilibrium moisture contents for loam, sandy loam, and loamy sand soils would be 17.6%, 6.2%, and 4.2%, respectively.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.4
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• pp.176-184
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• 2011

Cold air on sloping surfaces flows down to the valley bottom in mountainous terrain at calm and clear nights. Based on the assumption that the cold air flow may be the same as the water flow, current models estimate temperature drop by regarding the cold air accumulation at a given location as the water-like free drainage. At a closed catchment whose outlet is blocked by man-made obstacles such as banks and roads, however, the water-like free drainage assumption is no longer valid because the cold air accumulates from the bottom first. We developed an empirical model to estimate quantitatively the effect of cold pool on nocturnal temperature in a closed catchment. In our model, a closed catchment is treated like a "vessel", and a digital elevation model (DEM) was used to calculate the maximum capacity of the cold pool formed in a closed catchment. We introduce a topographical variable named "shape factor", which is the ratio of the cold air accumulation potential across the whole catchment area to the maximum capacity of the cold pool to describe the relative size of temperature drop at a wider range of catchment shapes. The shape factor is then used to simulate the density profile of cold pool formed in a given catchment based on a hypsometric equation. The cold lake module was incorporated with the existing model (i.e., Chung et al., 2006), generating a new model and predicting distribution of minimum temperature over closed catchments. We applied this model to Akyang valley (i.e., a typical closed catchment of 53 $km^2$ area) in the southern skirt of Mt. Jiri National Park where 12 automated weather stations (AWS) are operational. The performance of the model was evaluated based on the feasibility of delineating the temperature pattern accurately at cold pool forming at night. Overall, the model's ability of simulating the spatial pattern of lower temperature were improved especially at the valley bottom, showing a similar pattern of the estimated temperature with that of thermal images obtained across the valley at dawn (0520 to 0600 local standard time) of 17 May 2011. Error in temperature estimation, calculated with the root mean square error using the 10 low-lying AWSs, was substantially decreased from $1.30^{\circ}C$ with the existing model to $0.71^{\circ}C$ with the new model. These results suggest the feasibility of the new method in predicting the site-specific freeze and frost warning at a closed catchment.

• The Korean Journal of Quaternary Research
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• v.13 no.1
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• pp.67-78
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• 1999

In present, the terminal area of the Nagdong River Delta consists of micro-depositional landforms with sand barrier islands, sand bars and tidal flats which are arranged parallel to the present shoreline, and have rapidly shifted toward sea during last 100 years due to human activities such as construction of estuary dam, industrial complex and residential area. To clarify the landform changes of the area, the author traced the morphologic change pattern based on interpretation of air-photos, topographic maps and old Korean traditional map, and the results are as follows ; Based on the Daedongyeojido, one of the old Korean map, published in 1861, the area including upper part of the delta was underlying by sea level except two larger sand barriers, which means the Nagdong River Delta was not completely formed as the present outline of morphology by 1860s. According to the topographic map(1 :50,000) of 1916, the delta resembled to the present morphology pattern was exposed in 1916, and at this time the area was mainly composed of one sand barrier island, four sand bars and tidal flats, which had slowly elongated southwards before construction of the Nagdong River Estuary Dam in 1987. But after 1987, the area has been rapidly and drastically shifted southwards in arrange with one chain of sand barrier islands (Elsugdo -Myeonghodo-Sinhodo ) and four chains of sand bars (first chain ; Jinwoodo -Daemadeung-Maenggeummeorideung, second chain : Jangjado-Baeghabdeung, third chain ; Saedeung-Namusitdeung, fourth : Doyodeung-Dadaedeung) parallel to shoreline. This rapid landform change of the area is now occurring, and is seemed to ascribed firstly, to the construction of the Nagdong River Estuary Dam on Elsugdo in 1987, the Sinho Industrial Complex on Sinhodo and Myeongji Residential Area on Myeonghodo in 1992, secondly, to artificial alteration of drainage channel and consequential breakdown of former energy system between riverflow and tidal-and wave-energy. From these facts, it is inferred that the landform change pattern of the area will continue until a new equilibrium between the factor available to this energy system is accomplished.

• Water for future
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• v.14 no.4
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• pp.13-18
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• 1981

The rainfall pattern analysis on time distribution characteristics of rainfall rates in important in determination of design flow for hydraulic structures, particularly in urban area drainage network system design. The historical data from about 400 storm samples during 31 years in Seoul have been used to investigate the time distribution of 5-minute rainfall in the warm season. Time distribution relations have been deveolped for heavy stroms over 20mm in total rainfall and represented by relation percentage of total storm rainfall to percentage of total storm time and grouping the data according to the quartile in which rainfall was heaviest. And also time distribution presented in probability terms to provide quantitative information on inter-strom variability. The resulted time distribution relations are applicable to construction of rainfall hyetograph of design storm for determination of design flow hydrograph and identification of rainfall pattern at given watershed area. They can be used in conjuction with informations on spatstorm models for hydrologic applications. It was found that second-quartile storms occurred most frequently and fourth-quartile storms most infrequently. The time distribution characteristics resulted in this study have been presented in graphic forms such as time distribution curves with probability in cumulative percent of storm-time and precipitation, and selected histograms for first, second, third, and fourth quartile stroms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.1
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• pp.53-62
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• 1982

An effort of preliminary type has been made to develope a practical method for the waterway area determination of a drainage outlet in rural or agricultural areas. The Seoul meteorological station was selected as tile index station, and the maximum rainfalls-duration-frequency (R-D-F) relation of short-time intense rainfalls was first established. A frequency analysis of the daily rainfalls for the 75 stations selected throughout the country resulted the 50-year daily rainfall for each station. The rainfall factor, which is defined here as the ration of 50-year daily rainfalls of individual station and the index station, was determined for the 8 climatological regions divided in this study. Following the US SCS method the runoff number of a watershed was given based on the soil type, land-use pattern, and the surface treatment. With this runoff number and the R-D-F relationship the runoff factors for the index station were computed and hence a nomogram could be drawn which makes it possible to determine the runoff factor for a given rainfall number and a rainfall of specific duration and frequency. With this done, the potential runoff of a watershed for a given rainfall duration could be calculated, based on the unit hydrograph theory, by multiplying the rainfall factor, the runoff factor, and the drainage area of the watershed under consideration. Then, the maximum runoff potential was determined by varying the rainfall duration and finding out the duration which results the peak discharge of a gived return period.