• Journal of Korea Water Resources Association
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• v.45 no.12
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• pp.1259-1273
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• 2012

In this study, a watershed-based surface water and groundwater integrated model, SWAT-MODFLOW was used to quantify the stream flow depletion due to groundwater pumping for the Sinduncheon watershed. Complex water use conditions such as water taken from a stream, sewage disposal release, irrigation from agricultural reservoir, groundwater pumping were considered for simulations. In particular, the model was revised to reflect the effects of reservoir operation and return flow from the used groundwater on streamflow variation. The simulated results showed that the groundwater pumping at current status has induced the decrease of more than 10% in annual average streamflow and 40% in drought flow at the outlet of the Sinduncheon watershed, The simulated results also revealed that the vast water withdrawals at green house areas during winter season have dramatically changed streamflow from April to June. The streamflow depletion was mainly attributed to pumping wells located within the distance of 300 m from the stream for Sinduncheon watershed.

• Journal of Korea Water Resources Association
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• v.50 no.3
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• pp.211-221
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• 2017

In statistical hydrology, various extreme distributions such as the generalized extreme value (GEV), generalized logistic (GLO) and Gumbel (GUM) models have been widely used to analyze the extreme events. In the case of rainfall events in South Korea, the GEV and Gumbel distributions are known to be appropriate among various extreme distribution models. However, the proper probability distribution model may be different depending on the type of extreme events, rainfall duration, region, and statistical characteristics of extreme events. In this regard, it is necessary to apply a wide range of statistical properties that can be represented by the distribution model because it has two shape parameters. In this study, the statistical applicability of rainfall data is analyzed using the Burr XII distribution and the dimensionless L-moment ratio for 620 stations in South Korea. For this purpose, L-skewness and L-kurtosis of the Burr XII distribution are derived and L-moment ratio diagram is drawn and then the applicability of 620 stations was analyzed. As a result, it is found that the Burr XII distribution for the stations of the Han River basin in which L-skewness is relatively larger than L-kurtosis is appropriate, It is possibility of replacing the distribution of commonly used Gumbel or GEV distributions. Therefore, the Burr XII model can be replaced as an appropriate probability model in this basin.

• Journal of Korea Water Resources Association
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• v.50 no.11
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• pp.769-779
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• 2017

As the occurrence of drought is recently on the rise, the reliable drought forecasting is required for developing the drought mitigation and proactive management of water resources. This study developed a probabilistic hydrological drought forecasting method using the Bayesian Networks and drought propagation relationship to estimate future drought with the forecast uncertainty, named as the Propagated Bayesian Networks Drought Forecasting (PBNDF) model. The proposed PBNDF model was composed with 4 nodes of past, current, multi-model ensemble (MME) forecasted information and the drought propagation relationship. Using Palmer Hydrological Drought Index (PHDI), the PBNDF model was applied to forecast the hydrological drought condition at 10 gauging stations in Nakdong River basin. The receiver operating characteristics (ROC) curve analysis was applied to measure the forecast skill of the forecast mean values. The root mean squared error (RMSE) and skill score (SS) were employed to compare the forecast performance with previously developed forecast models (persistence forecast, Bayesian network drought forecast). We found that the forecast skill of PBNDF model showed better performance with low RMSE and high SS of 0.1~0.15. The overall results mean the PBNDF model had good potential in probabilistic drought forecasting.

• Journal of Sericultural and Entomological Science
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• v.52 no.2
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• pp.123-128
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• 2014

We carried out an ecological survey for Ceratovacuna japonica, which lives in bamboos, at the experimental field of National Academy of Agricultural Science, Suwon and the several natural fields in Korea from 2010 to 2011. The releasing methods of C. japonica on Pseudosasa japonica was more effective at the brushing-off method than the pining-attached method. The successful rate of releasing was the highest at green house than others such as at outdoor, vinyl green house and in a insects net conditions. The survival limit of C. japonica was closely associated with the lowest temperature ($-10^{\circ}C$) of vegetative limit of P. japonica for over wintering because of two fields of Ilsan lake park and Guri ecological park showed falling down below $-15^{\circ}C$ two times in January. It provides for a reasonable distribution information of C. japonica that is restricted to south of Han River. However, the middle of Korea has rarely fallen down below $-10^{\circ}C$. Therefore, we consider that a successful rearing of C. japonica may be the most suitable in green house condition to overcome winter period.

• Tunnel and Underground Space
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• v.22 no.4
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• pp.227-242
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• 2012

Youngju multipurpose dam is planned to minimizing the damage by flood and obtaining the water for industrial use in Nakdong river region. Faults in rock mass have strong influences on the behaviors of dam structure. Thus, it is very important to analyse for the characteristics of fault rocks in dam design. However, due to the limitation of geotechnical investigation in design stages, engineers have to carry out the additional geological survey including directional boring to find the distribution of faults and the engineering properties of faults for stability of dam. Especially, the selection of location of dam and type of dam considering fault zone must be analyzed through various experimental and numerical analysis. In this study, various geological survey and field tests were carried out to analyse the characteristics of the large fault zone through the complex dam is designed in foundation region. Also, the distribution of structural geology, the shape of faults and the mechanical properties of fault rock were studied for the reasonable design of the location and type of dam for long-term stability of the complex dam.

• 한국해양학회지
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• v.24 no.4
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• pp.184-193
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• 1989

An investigation on the soft-bottom macrobenthic community in the inner Kyeonggi Bay was conducted in July, October of 1987 and February, May of 1988. The benthic fauna comprised a total of 87 species and showed mean density of 550 indiv./$m^2$. Major faunal groups are polychaetes, molluks, and crustaceans, corresponding to 64.7%, 17.4%, and 15.2% in total abundance respectively. The most abundant species was Tharyx sp. (10.9%), and followed by Mactra veneriformis (10.5%), Mediomastus sp. (8.6%), and Glycinde sp. (8.0%) etc.. The important species in the intertidal zone were Mactra veneriformis, Hinia festiva, and Nephtys californiensis, whereas those in subtidal channel region were Tharyx sp., mediomastus sp., Sternaspis scutata, and Nephtys polybranchia. The study area could be divided into 4 station groups based on the species composition; two groups within interidal flat and two in channel regions. Each station group sustained its specific benthic faunal assemblage; Mactra-Hinia, Aricidea-Haploscoloplos assemblages in the intertidal flat and Harpiniopsis-Urothoe, Mediomastus-Sternaspis assemblages in the subtidal channel region. The Mediomastus-Sternaspis assemblage showed the highest species number and population density, and also did the highest diversity and evenness indices. The Harpiniopsis-Urothoe assemblage showed the poor species composition and abundance, and so recorded the highest dominance index. Two assemblages in the intertidal flat had the intermediate values in all the biological parameters. The northern channel region of zone S-2 showed the high abundance in species composition, which seems to be caused by the heterogeneous sediment and the organic enrichment from the Han River and the Incheon industrial complex.

• Korean Journal of Ecology and Environment
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• v.35 no.4 s.100
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• pp.295-305
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• 2002

Benthic macro- invertebrates were collected in a 200 m reach located in the $3^{rd}$ order Yangjae Stream, a tributary of the Han River, Seoul, from April 1996 to March 1998. Although species richness was relatively low due to organic pollution, community abundance patterns appeared to be different depending upon location of the sampling sites. At the sample sites in the straight zone with high water velocity and large substrates, species richness was high and species relatively less-tolerant to organic pollution was additionally present. At the sample sites in the pool zone with lower velocity and high sedimentation, species richness was low and a few tolerant species to organic pollution were abundantly collected. The principle component analysis indicated that some sample sites in the straight zone appeared to be related to water velocity and shear velocity, and associated with diverse taxa less tolerant to organic pollution. Additionally the sample site transplanted with large substrates was associated wit]h hydraulic characters such as substrate diversity and roughness, and was related to species indicating partial recovery of water. The sample sites located at the pool zone tended to be associated with organic matter that had sedimented on to the substrates and the taxa tolerant to organic pollution, including Oligochaeta and Chironomus.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.459-467
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• 2007

The effects of turbid water on fish community was investigated in a clear reference stream (the Bongsan Steam) and a turbid stream (the Daegi Stream) located in the upstream region of the South Han River, Korea. The stress index (SI) of suspended solids (SS) were calculated during a rain event concentration by the equation SI=LN (SS${\times}$duration). EMC of SS was $1{\sim}13$ mg $L^{-1}$ in the clear stream with a mean SI of 5.2, while SS was $97{\sim}1,150$ mg $L^{-1}$ in the turbid stream with a mean SI of 10.3. Even though the number of species was not much different, the dominant species of the two steams were distinctly different. The reference stream was dominated by upstream species such as Rhynchocypris kumgangensis, Brachymystax lenok tsinlingensis, and Cottus poecilopus which are typical upstream community. Whereas the turbid streams was dominated by Rhynchocypris kumgangensis, Zacco koreanus, and Orthrias nudus which are representatives of middle reache community. Fish density was four times higher in the clear steam than the turbid stream. In the similarity analysis of fish communities the community of the turbid stream showed large dissimilarity with other communities in other streams of similar size. In conclusion, although turbidity might be at the sublethal concentration, fish communities are under stress in some turbid streams of Korea that is strong enough to induce community change. It can be an example of a chronic ecological toxicity of turbidity at the community level.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.277-291
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• 2020

Shield TBM is a tunnelling method that has a wider range of applications in the poor ground condition compared to conventional tunnels (Drill and Blast). Currently, a 13.3 m large-diameter slurry shield TBM is preparing for construction to pass under the Han River. Shield TBM is divided into slurry and EPB shield TBM, and management items during construction are different depending on each characteristic. In this paper, the equipment type, origin, application case and trouble case were analyzed for slurry shield TBM, which is mainly constructed in soft ground. In addition, 2D and 3D model tests were conducted on the condition of soil depth for the possibility of slurry leakage into front of the equipment, with appropriate chamber pressure. Based on this paper, it proposed to provide basic and reference data for proper excavation surface pressure and chamber pressure during construction of slurry shield TBM under soft ground conditions, and proposed measures to minimize stability and environmental decline due to slurry ejection.

• Korean Journal of Remote Sensing
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• v.22 no.4
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• pp.243-253
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• 2006

As the ocean and beaches have suffered from the losses of sand, it is necessary to monitor the zones that are prone to erosion continuously with the object of the long-term management. However, each ward offices are busy trying to supply sand without analyzing the marine and beach topographic changes. Therefore a long term effect of erosion has not been shown. In this study, we proposed methods to collect accurate spatial data of the oceans and beaches through sounding and GPS surveys, and detected and analyzed topographic changes quantitatively and qualitatively, by using an integrated RS and GIS techniques. The result of this study revealed that the marine topography has been eroded for 25 years, because of the straight construction of the river and the vast development of urban features, in addition with change of the mean depth 0.40 m, the water surface area 11,028 $m^2$, and submarine volume 2,207,884 $m^3$. The beach topography has accreted for 5 years and the change of the mean elevation is 0.27m, the area 6,501 $m^2$, and volume 25,667 $m^3$, because of the installation of geogrids and the seasonal effect. We conducted monitoring works on the topographic survey of the ocean and beaches and analyzed the present condition of the coastal erosions. Therefore, it is estimated that necessary information on the supply of sand, the safe marine leisure and the management of bating place could be provided.