• Journal of Soil and Groundwater Environment
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• v.20 no.5
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• pp.26-33
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• 2015

Batch experiments were performed to investigate the feasibility of a surfactant-enhanced soil washing process for soils heavily contaminated with crude oil in Kuwait. TPH concentration of the contaminated soil was 223,754 mg/kg, sampled from the bottom of a vaporized oil extraction pond in the Burgan reservoir field. Commercialized eight nonionic surfactants (Tween and Tergitol series) were used to measure the aqueous solubility for the crude oil. Among them, two Tergitol surfactants were used to evaluate the TPH removal efficiency of the surfactant-enhanced soil washing for heavily contaminated Kuwait soil. The solubility of the crude oil in surfactant solution was in the order Tergitol 15-S-7 > Tergitol 15-S-9 > Tergitol 15-S-12 > Tween-80 > Tween-20 > Tween-60, which showed that the crude oil solubilities of the Tergitol series were higher than those of the Tween series. The TPH removal efficiencies of 2% and 5% Tergitol 15-S-9 solution were 59% and 65%, respectively. Because the residual TPH concentration in the washed soil was still higher than the clean-up level (10,000 mg/kg), the soil washing process was repeated five times. After the fifth washing, the residual TPH concentration in the soil went down to 7,680 mg/kg and its removal efficiency was 97%.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.1
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• pp.71-79
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• 2014

In this study, an experiment with large-scale model was performed according to raising the embankment in order to investigate the behavior of failure for embankment and spillway transitional zone due to overtopping. The pore water pressure, earth pressure, settlement and failure pattern by a rapid drawdown and overtopping were compared and analyzed. The pore water pressure and earth pressure at spillway transitional zone by overtopping increased a rapidly with the expansion of seepage erosion, but the crest showed a smally change due to effect of the inclined core type. And it is considered an useful data that can accurately estimate the possibility of failure of the reservoirs. A settlement at overtopping decreased a rapidly due to failure of crest. The relative settlement difference due to change of the water level at the upstream and downstream slope cause increase largely crack of crest. The behavior of failure by overtopping was gradually enlarged towards reservoirs crest from the bottom of the spillway transition zone, the inclined core after the raising the embankment was influenced significantly to prevent the seepage erosion.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1045-1052
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• 2009

A calculation model is developed to predict the transient free surface flow on the containment floor following a loss-of-coolant accident (LOCA) of pressurized water reactors (PWR) for the use of debris transport evaluation. The model solves the two-dimensional Shallow Water Equation (SWE) using a finite volume method (FVM) with unstructured triangular meshes. The numerical scheme is based on a fully explicit predictor-corrector method to achieve a fast-running capability and numerical accuracy. The Harten-Lax-van Leer (HLL) scheme is used to reserve a shock-capturing capability in determining the convective flux term at the cell interface where the dry-to-wet changing proceeds. An experiment simulating a sudden break of a water reservoir with L-shape open channel is calculated for validation of the present model. It is shown that the present model agrees well with the experiment data, thus it can be justified for the free surface flow with accuracy. From the calculation of flow field over the simplified containment floor of APR1400, the important phenomena of free surface flow including propagations and interactions of waves generated by local water level distribution and reflection with a solid wall are found and the transient flow rates entering the Holdup Volume Tank (HVT) are obtained within a practical computational resource.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.953-963
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• 2013

Reliable long-term streamflow forecasting is invaluable for water resource planning and management which allocates water supply according to the demand of water users. Forecasting of seasonal inflow to Andong dam is performed and assessed using statistical methods based on hydrometeorological data. Predictors which is used to forecast seasonal inflow to Andong dam are selected from southern oscillation index, sea surface temperature, and 500 hPa geopotential height data in northern hemisphere. Predictors are selected by the following procedure. Primary predictors sets are obtained, and then final predictors are determined from the sets. The primary predictor sets for each season are identified using cross correlation and mutual information. The final predictors are identified using partial cross correlation and partial mutual information. In each season, there are three selected predictors. The values are determined using bootstrapping technique considering a specific significance level for predictor selection. Seasonal inflow forecasting is performed by multiple linear regression analysis using the selected predictors for each season, and the results of forecast using cross validation are assessed. Multiple linear regression analysis is performed using SAS. The results of multiple linear regression analysis are assessed by mean squared error and mean absolute error. And contingency table is established and assessed by Heidke skill score. The assessment reveals that the forecasts by multiple linear regression analysis are better than the reference forecasts.

• Geomechanics and Engineering
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• v.15 no.4
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• pp.965-972
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• 2018

In deep braced excavations, struts and walers play an essential role in the whole supporting system. For multi-level strut systems, accidental strut failure is possible. Once a single strut fails, it is possible for the loads carried from the previous failed strut to be transferred to the adjacent struts and therefore cause one or more struts to fail. Consequently, progressive collapse may occur and cause the whole excavation system to fail. One of the reasons for the Nicoll Highway Collapse was attributed to the failure of the struts and walers. Consequently, for the design of braced excavation systems in Singapore, one of the requirements by the building authorities is to perform one-strut failure analyses, in order to ensure that there is no progressive collapse when one strut was damaged due to a construction accident. Therefore, plane strain 2D and three-dimensional (3D) finite element analyses of one-strut failure of the braced excavation system were carried out in this study to investigate the effects of one-strut failure on the adjacent struts.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1997.11a
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• pp.97-142
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• 1997

The Seoguipo Formation occurs only in a small exposure along the coast of the Seoguipo City, but in the subsurface, underlies tile western part of the Bugcheon-Pyoseon Line in the northeastern part of tile island. The Bugcheon-Pyoseon Line is presumed to be a facies boundary that reflects tile distribution of hyaloclastites resulted from submarine volcanic activity. The Seoguipo Formation is distributed in the subsurface along the part which is lower than 400m in average altitude, and occurs at El. -5.76∼-46.63m in tile southern area, El. -41.89∼-57.97m in the western area, El. -13.15∼-50.59m in the northern area. Therefore, the southern area was uplifted after the deposition of the Seoguipo Formation. In the subsurface, the vertical depth of the volcanic rocks of the Cheju Volcanic Edifice is El. -40.6m in the southern area, El. -111.3m in the western area, El. -81.5m in the northern area and El. -134.7m in the eastern area. The unconsolidated U Formation, which is, overlying the basement and about 70∼250m thickness underlies the whole island. There is a positive correlation between tile groundwater level and the depth of the subsurface distribution of the Seoguipo Formation. Consequently, it is conformed that the subsurface distribution of the Seoguipo Formation plays important role for controlling the characteristics of the reservoir of tile groundwater in Cheju Island.

• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.8-15
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• 2005

Wave energy has been considered to be one of the most promising energy resources for the future, as it is pollution-free and an abundant natural resource. However, since it has drawbacks of non-stationary energy density, it is necessary to change the wave energy into a simple concentrated energy. Progressive waves in a coastal area can be amplified, swashed, and overtopped by a wave overtopping control structure. By conserving the quantity of overflow in a reservoir, the kinetic energy of the waves can be converted to the potential energy with a hydraulic head above the mean sea level. The potential energy in the form of a hydraulic head can be utilized to produce electric power, similar to hydro-electric power generation. This study aims to find the most optimal shape of wave overtopping structure for maximum overtopping volume of sea water; for this purpose, we carried out the wave overtopping experiment in a wave tank, under both regular and irregular wave conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.107-114
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• 1992

With the increasing of impervious area and shortening of travel time, the risk of flooding in urban area becomes a serious problem in Seoul metropolitan area, and its alternatives are needed. In this study, one of urban flood alternatives, a fuzzy control technique is applied in pumping station to test its drainage capacity of inland inflow, and compared with existing pumping criteria (controled by water level). Three design rainfalls(10, 30, and 50 year) are applied to ILLUDAS model to calculate inflow in detention reservoir. To check the efficiency of fuzzy control, two fuzzy rules are used in the operation of pumping station. In these results, fuzzy control rules, based on the experiences of experts, show applicability in practice and effectiveness in inland flooding prevention.

• Water for future
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• v.9 no.1
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• pp.86-100
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• 1976

To study influences on the downstream, and the Gunsan harbor by setting up estuary of the Gumgang, available data which were collected from the measuring stations which were established within the river basin of which results attained are as follows: 1. The discharge can be calculated as the relationship between the discharge and precipitation in the basin is $R=4{\times}10^{-4}p^2$ or R=P-600 2. The discharge flow in to small resevoirs in the basin can be estimated as $QR=QS\frac{PR-600}{PS-600}(\frac{AR}{AS})$ 3. This daily average discharge at Kongju is 31% less than the during maximum probable discharge and that in Okcheon is 48% less than the daily maximum probable flood. 4. The maximum probable flood from the small stream in the basin can be estimated by a $Q=82.45A^{0{\cdot}464}$ 5. Sediments can be computed with Qs (suspended load)=1.41 $Q^{1{\cdot}42}$ and Qb (bed load)=165.2 $Q^{0{\cdot}705}$. 6. By setting up the specific estuary the tidal movement will be reduced to 93.6% on the average and the sedimentation is reduced to 96.0%. Upon review of overall analysis, the dead wate level of estuary of Gumgang will completely sedimented in next 30 years, therefore, the dredging work at Gunsan harbor is reduced to 73.6%, it is considered that life length will be extended about 52years taking account the existing condition.

• Journal of Plant Biology
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• v.38 no.1
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• pp.39-45
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• 1995

Glycine soja Sieb. et Zucc., a predominantly selfing annual, has been served as a reservoir of germplasm for soybean, G. max (L.) Merr., cultivar improvement. This study describes the levels and distribution of genetic variation within and among 22 Korean populations of G. soja using starch gel electrophoresis. The species maintains very similar levels of genetic variability within populations observed in most other annuals. At the population level, the mean percent of polymorphic loci (P) was 32.6%, mean number of allele per locus (A) was 1.32, and mean expected heterozygosity (He) was 0.112. In addition, total genetic diversity (HT) calculated only for polymorphic loci was 0.347. However, significant differences in allele frequencies among populations were found for all loci (P<0.001 in each case) and, on average, about 70% of the total variation in the species is common to all populations. Indirects estimate of the number of migrants per generation (Nm=0.58, calculated from mean GST) indicates that gene flow is low among Korean populations of the species. In addition, analysis of fixation indices revealed a substantial heterozygote deficiency in most populations and at all loci. This indicates that most populations sampled may have been substructed largely due to inbreeding (predominantly selfing) and restricted gene flow, coupled with founder effect and genetic drift. Considering a high genetic divergence among populations, it is recommended that several Korean populations of the species should be preserved, especially such as populations in the eastern and southeastern Korean peninsula with high variation.