• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1305-1310
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• 2005

As a way to the optimum design of the collector well lateral in riverbed filtration, experiments were performed using sand tanks which were connected to form a model lateral system. Measured were the residual hydraulic heads along the laterals, the discharge rates at each sand tank and the production rates at the collector well while the model laterals were operated with various scenarios of changing parameters including water level of the collector well, the lateral diameter and length, and the hydraulic conductivity of the sand. Results showed that riverbed filtration could be more efficient when the resistance in the lateral was weak compared with the resistance in the sand, which was indicated by the more flattened distribution of the residual hydraulic heads along the lateral. Results also showed that the discharge rate increased exponentially with the approach to the collector well, and that the exponent increased as the lateral diameter decreased and/or the hydraulic conductivity of the sand increased. It was also seen that the well production increased with the increase in the lateral length and diameter although the marginal productivity decreased. It could be concluded that the axial flow velocity in the lateral was an important factor governing the efficiency of a lateral in riverbed filtration and that the maximum entrance velocity to the collector well, over which the efficiency decreased drastically, was about 1 m/sec under the conditions of this study.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.392-400
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• 1993

The present study was accomplished to understand the occurrence and time serial variations of oxygen-deficient watermass in wonmun Bay from 1989 to 1991. From the results of this work, oxygen-deficient water was periodically observed in bottom layer and in Summer in this region. The stratification of water began to develop in Spring and the strong formation of oxygen-deficient water showed in Summer but it gradually disappeared in Autumn. It seems that the occurring and continuing period of very low dissolved oxygen watermass is intensively controlled by meteorological conditions and vortical stratification of water column. On formation of oxygen-deficient watermass, high nutrient concentrations in the bottom layer appear to be due to release of nutrients from bottom sediment. The dissolved inorganic phosphate versus AOU shows two linear curves according to the level of AOU. In the relationships between phosphate and AOU, the gradient of a linear curve over approximately 5mg-AOU/l was significantly large, presumably indicating dissolution of phosphate from the sediment.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.08a
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• pp.25-48
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• 2004

Structures show the phehomena of deformation and lowering of function with time-lapse by artificial environments and changes of geotechnical conditions or accumulation of initial deformation elements. This study aims the structural assessment of cultural property, Chum-Sung-Dae, located in Kyeongju city, Korea. It was built about 1,300 years ago, and has undergone deformation and ground-subsidence with time-lapse. Non-destructive evaluation techniques were applied to the Chum-Sung-Dae, to protect it from survey Because of this reason, 3D precise laser scanning surveying system was applied to measure the exact size of Chum-Sung-Dae, displacement and declining angles. Geophysical exploration also was applied to study the subsurface distribution of geotechnical parameters or physical properties. Natural frequencies were measured from real and model of Chum-Sung-Dae to study the dynamic characteristics of vibration and/or earthquake load and stiffness of structures.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.371-379
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• 2004

Soil investigation data at 7 different locations around Honam costal region were analyzed and experimental correlations between soil properties and parameters of soft clay were presented. Most soils were classified as CL and CH by the Unified Soil Classification System and were unstable structurally because the water contents were generally greater than the liquid limits. The compression index has good correlations with water content, liquid limit and initial void ratio. The trend of these correlations were similar to the Skempton equation Cc = 0.009(LL -10) and other studies for Korean soft clays but the constants were small different. The slope of these correlations for Honam costal region were slightly greater than those for Kyunggi costal region and Kyungnam costal region. The correlation coefficient (R) between the liquid limit and the plastic index is 0.93. It is seen that not only the water content and the liquid limit but also the water content and the initial void ratio are correlate, therefore the experimental equations were presented for the practical purpose.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.305-310
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• 1983

Spatial variability of infiltration rates of 96 samples from Hwadong SiCL was studied by using geostatistical concepts. The measurement was made at the nodes of the regular grid consisting of 12 rows and 8 columns. Sample spacing within rows and columns was 3 and 2 meters, respectively. This study illustrated the use of variogram as a tool to identify the degree of dependency of the infiltration rate on the distance between pairs of measurements and how to take advantage of this dependency. Fractile diagram showed that the distribution of observation was approximately normal. The range of the variogram was about 7.4 meters. The minimum number of samples necessary to reproduce the results similar to the 96 measured values was 8 to 10. Coefficients of theoretical variogram function for computing kriged values and kriged varionces of nuogget effect, slope, and range were 0.444 cm/day, 0.003 cm/day, and 7.4 m, respectively.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.21-26
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• 1999

To investigate the combined effect of radiation and pesticide on Tradescantia somatic cell mutations, potted plants of Tradescantia 4430 on which parathion had been sprayed evenly 24 hours before irradiation. Radiation doses were 0.3, 0.5, 1.0 and 2.0 Gy of gamma-ray. The plants irradiated only with the gamma-ray radiation were used as control groups (CT). Pink mutation frequency increased linearly proportional to the radiation dose and the peak interval of elevated mutation frequencies appeared during 7 ~ 11 days after irradiation in both CT and Pa +${\gamma}$ groups. The slope of dose -response curve in CT was 5.99 ($r^2$= 0.988), while it was 3.43 (r$x^-2$=0.981) in Pa+${\gamma}$. It seemed that parathion pretreatment had a protective effect against radiation-induced cell damages since it decreased the slope value by 43%. It is suggested that an adaptive response or radiomodification could be induced in irradiated stamen hair cells by parathion pretreatment.

• Journal of Fisheries and Marine Sciences Education
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• v.8 no.1
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• pp.41-47
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• 1996

The fishing experiment was carried out in order to analyses the mesh selectivity for trawl cod - end in the Southern Korean Sea and East China Sea from June,1991 through December, 1992. The mesh selectivity was examined for the five kinds with opening mesh size, of which having mesh s izes 51.2mm, 70.2mm, 77.6mm, 88.0mm and 111.2mm. In this report, mesh selectivity were taken analyses trawl cod - end for Priacanthus macracanthus. The main results obtained were as follows : 1. The relation equations between total length(TL) and body height(BH), body girth(BG) and body weight(BW) were BH=0.256 TL+2.963, BG=0.620 TL+8.650 and $BW=7.34{\times}10^{-5}TL^{2.6956}$, respectively. 2. 50% selection length and selection factor of trial cod - end with opening mesh size having 51.2mm, 70.2mm, 77.6mm, 88.0mm were 94.8mm, 1.85 ; 159mm, 2.27 ; 204mm, 2.09 ; 217.3mm, 2.18, respectively. 3. Range of opening mesh size from 51.2mm to 88.0mm, parameters of master curve were slope 2.70, intercept - 5.7 and selection factor 2.11.

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.837-847
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• 2017

Land Surface Model (LSM) was developed for the Soyang river basin located in Korean Peninsula to clarify the spatio-temporal variability of hydrological weather parameters. Variable Infiltration Capacity (VIC) model was used as a LSM. The spatial resolution of the model was 10 km and the time resolution was 1 day. Based on the daily flow data from 2007 to 2010, the 7 parameters of the model were calibrated using the Isolated Particle Swarm Optimization algorithm and the model was verified using the daily flow data from 2011 to 2014. The model showed a Nash-Sutcliffe Coefficient of 0.90 and a correlation coefficient of 0.95 for both calibration and validation periods. The hydrometeorological variables estimated for the Soyang river basin reflected well the seasonal characteristics of summer rainfall concentration, the change of short and shortwave radiation due to temperature change, the change of surface temperature, the evaporation and vegetation increase in the cover layer, and the corresponding change in total evapotranspiration. The model soil moisture data was compared with in-situ soil moisture data. The slope of the trend line relating the two data was 1.087 and correlation coefficient was 0.723 for the Spring, Summer and Fall season. The result of this study suggests that the LSM can be used as a powerful tool in developing precise and efficient water resources plans by providing accurate understanding on the spatio-temporal variation of hydrometeorological variables.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.105-114
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• 2004

Consolidation characteristics have been investigated by using Rowe cell consolidation tester for dredged soil, which is more than two times as much as the liquid limit. To examine the effects of variation of water content on consolidation characteristic, tests were carried out varying the initial water content from $100\%\;to\;150\%.$ The results were compared with the consolidation characteristics of remolded clay. The test results showed that the hither the initial water content of dredged clay was, the more noticeable the non-linear behavior of e-log P curves occurred. The variation of the gradient was apparent to load stage 40kPa and became less apparent after load stage 80kPa on the e-log P curves. Ratio of compression index stayed within the range suggested by Mesri and variation of initial water content has hardly influenced the coefficient of consolidation. On the contrary, it was found that the magnitude of consolidation load affects the vertical coefficient of consolidation. The variation of stratum thickness during consolidation processing needs to be taken into consideration since hydraulic fill would go through a much larger scale strain than land soil when it is subject to a load. In this study, the consolidation period considering the variation of stratum thickness was analyzed and the results were compared with those of existing consolidation studies which did not consider the variation of stratum thickness. According to the results of the study, the consolidation period of the ground with a larger strain was calculated more close to observed value in case of Mikasa theory which takes the variation of stratum thickness into consideration.

• Journal of the Korean Society for Railway
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• v.18 no.1
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• pp.8-14
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• 2015

This paper describes a prediction method for micro-pressure wave emitted from a tunnel on the Kyung-bu high-speed railway. Pressure and micro-pressure wave were measured simultaneously to obtain some constants for the prediction method. The change of a micro-pressure wave were analyzed according to the speed of the train, the track bed type, and the distance from a tunnel portal. At a train speed of 300km/h, the micro-pressure wave of 4.0km long ballast track tunnel is about 7.5Pa; that of 3.3km long slab track tunnel is about 14.3Pa The strength of the micro-pressure wave decreases in inverse proportion to the distance and becomes about 0.5~1.0Pa at a point of 100m from the tunnel exit. Micro-pressure waves were predicted using the formula with the obtained the constants. Using a comparison between the predicted data and field measurement data, it was confirmed that micro-pressure wave can be predicted easily through the prediction formula.