• Water for future
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• v.27 no.4
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• pp.85-94
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• 1994

A Sensitivity analysis on the model parameters involved in the Clark watershed routing method is made to demonstrate the effect of each parameter on the magnitude of 50-year design flood for small urban streams. As for the rainfall parameter the time distribution pattern of design storm was selected. For short duration storms Huff, Yen & Chow and Japanese Central type distributions were selected and the Mononobe distribution of 24-hour design storm was also selected and tested for Clark method application. The effect of SCS runoff curve number for effective rainfall and the methods of subbasin division for time-area curve were also tested. The routing parameter, i.e. the storage constant(K), was found to be the dominating parameter once design storm is selected. A multiple regression formula for K correlated with the drainage area and main channel slope of the basin is proposed for the use in urban stream practice for the determination of design flood by Clark method.

• Food Science and Preservation
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• v.19 no.1
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• pp.54-61
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• 2012

According to lifestyle changes, the consumers' concern about food also shifts from calories and nutrition to health and convenience. Fresh-cut produce is one of the new turns in the consumption pattern of fruits and vegetables. The increasing demand for it requires processors to make them stable in quality and safe from microorganisms. The results of the evaluation of the production process and hygienic management of fresh-cut lettuce revealed that the facilities used, such as the drainage holes, floors, and door knobs, were severely contaminated with microbes, and that the work equipment, workbenches, landing nets, and centrifuges were highly contaminated. Accordingly, improved production processes and management systems are necessary, as is the implementation of a quality control system from the stage of raw-material purchase to the distribution stage.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.633-642
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• 2004

This study tries to generalize the stream network by constructing rule-based modelling. A study on the map generalization tends to be concentrated on development of algorithms for modification of linear features and evaluations to the limited cartographic elements. Rule-based modelling can help to improve previous algorithms by application of generalization process with the results that analyzing mapping principles and spatial distribution patterns of geographical phenomena. Rule-based modelling can be applied to generalize various cartographic elements, and make an effective on multi-scaling mapping in the digital environments. In this research, nile-based modelling for stream network is composed of generalization rule, algorithm for centerline extraction and linear features. Before generalization, drainage pattern was analyzed by the connectivity with lake to minimize logical errors. As a result, 17 streams with centerline are extracted from 108 double-lined streams. Total length of stream networks is reduced as 17% in 1:25,000 scale, and as 29% in 1:50,000. Simoo algorithm, which is developed to generalize linear features, is compared to Douglas-Peucker(D-P) algorithm. D-P made linear features rough due to the increase of data point distance and widening of external angle. But in Simoo, linear features are smoothed with the decrease of scale.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.1
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• pp.13-20
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• 2012

In this study, the change pattern of hydrological response function as development has been observed. The target watershed was selected Tanbu sub-Basin in the Bocheong Basin. The applied channel networks are composed of 10 cases that are channel networks by strahler's ordering scheme and cases of all grids channel or the hillslope in basin. To each case of grid in basin, channel and hillslope drainage path lengths to outlet of basin are calculated, and hydrological response function was calculated by Nash Model. As results of this analysis, the peak discharge of hydrological response function is increased and peak time is shortened as development of channel networks. And based on statistical characteristics of hydrological response function, mean (lag time) and variance of travel time are reduced exponentially.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.81-89
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• 2001

In order to know relationships between green euglenoids and environmental factors, the species composition and density were assessed for 12 months together with environmental variables in the Jeonjucheon urban drainage, Korea. Nitrate was a high of 3.22 mg/1 in June and phosphate concentration was over 0.71 mg/l in the winter. The euglenoids totaled 5 genera and 71 species throughout the year, increasing in the early summer (35 to 42 texa) and decreasing in the winter (below 20 taxa). The number of green euglenoids positively correlated with surface water temperature. the total density of the green euglenoids showed a typical bimodal pattern, being maximal in the winter (5,394 cells/ml in June). The winter peak was a result of active growths of Euglena caudata, E. geniculata and E. viridis, however, each of which positively correlated with the phosphate. The early summer peak was attributed to Euglena deses, Lepocinclis ovum, and Phacus trypanon, each of which positively correlated with the ammonium and nitrate. The complete bimodal spectrum of species number and density of green euglenoids provides a sensitive image in detecting the changes of environmental variables in polluted waters such as Jeonjucheon.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.1
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• pp.49-60
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• 2004

Northern Gyeonggi Province(NGP), consisting of 3 counties, is the northernmost region in South Korea adjacent to the de-militarized zone with North Korea. To supplement insufficient spatial coverage of official climate data and climate atlases based on those data, high-resolution digital climate models(DCM) were prepared to support weather- related activities of residents in NGP Monthly climate data from 51 synoptic stations across both North and South Korea were collected for 1981-2000. A digital elevation model(DEM) for this region with 30m cell spacing was used with the climate data for spatially interpolating daily maximum and minimum temperatures, solar irradiance, and precipitation based on relevant topoclimatological models. For daily minimum temperature, a spatial interpolation scheme accommodating the potential influences of cold air accumulation and the temperature inversion was used. For daily maximum temperature estimation, a spatial interpolation model loaded with the overheating index was used. Daily solar irradiances over sloping surfaces were estimated from nearby synoptic station data weighted by potential relative radiation, which is the hourly sum of relative solar intensity. Precipitation was assumed to increase with the difference between virtual terrain elevation and the DEM multiplied by an observed rate. Validations were carried out by installing an observation network specifically for making comparisons with the spatially estimated temperature pattern. Freezing risk in January was estimated for major fruit tree species based on the DCMs under the recurrence intervals of 10, 30, and 100 years, respectively. Frost risks at bud-burst and blossom of tree flowers were also estimated for the same resolution as the DCMs.

• Economic and Environmental Geology
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• v.36 no.4
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• pp.275-284
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• 2003

We collected the samples of stream sediments from primary channels in order to establish natural background of major and minor elements for geologic units in the Gurye area. Stream sediments samples having no possibility of contamination effect and representing drainage basins composed of uniform geology, were collected from April to May in 1999, the chemical analysis of which was carried out. The tolerable level was used to investigate the enrichment degree of harmful elements. The contents of Ni and Cr exceeded the tolerance level in some sections. The tolerance level excess of those elements was regarded as the effect of the metamorphic rock which constituted the bed rock of the area. In order to identify the comprehensive enrichment pattern, the tolerable level was used in calculating the enrichment index. The enrichment index of harmful heavy metals showed that Granite gneiss area is 0.39, Porphyroblastic granite gneiss area 0.32, Biotite gneiss area 0.42, Migmatitic gneiss area 0.41, Tuff area 0.30, Andesite area 0.46, Conglomerate area 0.42, and Granite area 0.26. Those results showed that natural background of Gurye area had not been exposed to harmful heavy metal elements.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.962-964
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• 2003

In 2002 Thailand was faced with severe flooding in the North, Northeast and Central parts of the country caused by heavy rainfall of the monsoonal depression which brought about significant damages. According to the report by the Ministry of Interior and the Ministry of Agricultural and Co-operatives, the total damages were estimated to be about 6 billion bath. More than 850,000 farmers and 10 million livestock were effected. An area of 1,450,000 ha of farmland in 59 Provinces were put under water for a prolonged period. Satellite imageries were employed for mapping and monitoring the flood-inundated areas, flood damage assessment, flood hazard zoning and post-flood survey of river configuration and protection works. By integrating satellite data with other updated spatial and non-spatial data, likely flood zones can be predicted beforehand. Some examples of satellite data application to flood dis aster mitigation in Thailand during 2002 using mostly Radarsat-1 data and Landsat-7 data were illustrated and discussed in the paper. The results showed that satellite data can clearly identify and give information on the status, flooding period, boundary and damage of flooding. For comprehensive flood mitigation planning, other geo-informatic data, such as the elevation of topography, hydrological data need to be integrated. Ground truth data of the watershed area, including the water level, velocity, drainage pattern and direction were also useful for flood forecasting in the future.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.59-66
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• 2014

This paper presents the pullout behavior of suction pile using finite difference method; and the commercial software, FLAC3D, was employed for the numerical analyses. The ultimate pullout capacity of suction pile was predicted using conventional equations, and the results were compared with the results from numerical analyses with varying pile diameter, pile length, and the undrained shear strength of clays. Based on the results from 24 analyses, it was found that the failure pattern depends not only on the drainage condition of suction pile, but also on the pile dimensions and the material properties of surrounding soils. The developed side shear (DSS) along the internal surface of the suction pile was collected from numerical analyses, which was used to classify the failure type between sliding failure and tensile failure. Regardless of the external DSS, the high internal DSS tends to result in sliding failure in the numerical analyses, which conforms well to the estimation from conventional equations.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.4
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• pp.229-237
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• 2022

The sewer capacity design have been based on the Huff model or the rational equation in South Korea and often failed to determine optimal capacity, resulting in frequent urban flooding or over-sizing. A time distribution of rainfall (i.e., Huff or ABM method) could be used instead of a rainfall hyetograph obtained from statistical analysis of previous rainfalls. In this study, the Huff method and the ABM method, which predict the time distribution of rain intensity, which are widely used to calculate sewage pipe drainage capacity using the SWMM, were compared with the standard rainfall intensity hyetograph of Seoul. If the rainfall duration was 30 minutes to 180 minutes, the rainfall intensity value calculated by the Huff model tended to be less than the rainfall intensity value of the standard rainfall intensity in the initial 5-10 minutes. As a result, more than 10% to 30% of under-design would be made. In addition, the rainfall intensity value calculated by the Huff model from the section excluding the initial 5-10 minutes of rainfall to the rainfall duration was calculated larger than the value using the standard rainfall intensity equation, which would result in an over-design of 10% to 30%. In the case of a relatively long rainfall duration of 360 minutes (6 hours) to 1,440 minutes (24 hours), it showed an lower rainfall intensity of 60 to 90% in the early stages of rainfall, but the problem of under-design had been solved as the rainfall duration time had elapsed. On the other hand, in the alternating block method (ABM) method, it was found that the rainfall intensity at the entire period at each assumed rainfall duration accurately matched the standard rainfall intensity hyetograph of Seoul.