• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.839-850
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• 2018

The flood damage in urban areas due to torrential rain is increasing with urbanization. For this reason, accurate and rapid flooding forecasting and expected inundation maps are needed. Predicting the extent of flooding for certain rainfalls is a very important issue in preparing flood in advance. Recently, government agencies are trying to provide expected inundation maps to the public. However, there is a lack of quantifying the extent of inundation caused by a particular rainfall scenario and the real-time prediction method for flood extent within a short time. Therefore the real-time prediction of flood extent is needed based on rainfall-runoff-inundation analysis. One/two dimensional model are continued to analyize drainage network, manhole overflow and inundation propagation by rainfall condition. By applying the various rainfall scenarios considering rainfall duration/distribution and return periods, the inundation volume and depth can be estimated and stored on a database. The Rainfall-Duration-Flooding Quantity (RDF) relationship curve based on the hydraulic analysis results and the Self-Organizing Map (SOM) that conducts unsupervised learning are applied to predict flooded area with particular rainfall condition. The validity of the proposed methodology was examined by comparing the results of the expected flood map with the 2-dimensional hydraulic model. Based on the result of the study, it is judged that this methodology will be useful to provide an unknown flood map according to medium-sized rainfall or frequency scenario. Furthermore, it will be used as a fundamental data for flood forecast by establishing the RDF curve which the relationship of rainfall-outflow-flood is considered and the database of expected inundation maps.

• Journal of Korea Water Resources Association
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• v.52 no.3
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• pp.219-226
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• 2019

Recently, research about Low-Impact Development (LID) techniques has been expanded due to problems with the effects of climate change and urbanization that have been increasing. LID technology is used to control flood damage environmentally to reduce runoff and is reduce runoff on city also restore into previous water circulation system from present developed city. However, studies about quantitative data of LID techniques are insufficient. Therefore in this study, the Curve Number (CN) was calculated with the Planter Box, which is storage type LID technology to conduct the water circulation (infiltration, runoff, overflow) analysis. Rainfall intensity scenario (60.4 mm/hr, 83.1 mm/hr, 97.4 mm/hr, 108.2 mm/hr) about water circulation analysis of Planter Box is selected on the basis of probable rainfall intensity table. According to the experimental results, the storage rate of rainwater in Building Planter Box and Street Planter Box was 43.5% to 52.9% and 33.4% to 39%, respectively. In addition, CN value is estimated to 83 at the Planter box and the runoff reduction effect by applying Horton's infiltration capacity curve showed on 51% to 98%.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.221-221
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• 2015

Sustainable use of water resource and conservation of water quality are essential problems in the world. Especially, problems of water quality are serious one for human health as well as ecological system of all creatures on the earth. Recently, the importance of total effluent load as well as the concentrations of pollutant materials has been recognized not only for the conservation of water quality but also for sustainable water use in watersheds. However, the measurement or estimation of total effluent load from non-point source area such as farm lands or forests may be more difficult because both of concentration and discharge of the water are greatly changed depending on various factors especially metrological conditions such as rainfall, while the measurement from a point source area may be easy because the concentration of pollutant materials and amount of discharge water are relatively steady. Therefore, the total effluent load from a non-point source is often estimated by statistical relationships between concentration and discharge, which is called as L-Q equation. However, a lot of work and time are required to collect and analyze water samples and to get the accurate relationship or regressive equation. So, we proposed a new system for direct measurement of total effluent load of water quality from non-point source areas to solve the problem. In this system, the overflow depth at a hydraulic weir is measured with a pressure gage every hourly interval to calculate the amount of hourly discharge at first. Then, the operating time of a small electric pump to collect an amount of water which is proportional to the discharge is calculated to intake the water into a storage tank. The stored water is taken out a few days later in a case of storm event or several weeks later in a case of non-rainfall event and the concentrations of water quality such as total nitrogen and phosphorous are analyzed in a laboratory. Finally, total load of the water quality can be calculated by multiplying the concentration by the total volume of discharge. The system was installed in a small experimental forestry watershed to check the performance and know the total load of water quality from the forest. It was found that the system to collect a proportional amount of water to actual discharge operated perfectly and a total load of water quality was analyzed accurately. As the result, it was expected that the system will be very available to know the total load from a non-point source area.

• Management & Information Systems Review
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• v.38 no.1
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• pp.63-81
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• 2019

In order to overcome the disadvantages of banner ad, pop-up ad, interstitial ad, which are existing web advertisement forms, native ad is actively utilized. Native advertising is considered to be a useful advertising technique in that it can reduce users' rejection and attract attention. However, in recent years, there have been a lot of fake news and fake contents that have turned articles or video contents into advertisements. The purpose of this study is to understand how firms can coordinate and control native advertisements in a rational way. For this analysis, we conducted a survey of 308 social media users using quota sampling method. As a result of the verification, it was found that the more negative the perception of the evaluation of the advertisement, the less the level of persuasion about the advertisement and the negative impact on the website where the advertisement is exposed. In addition, this study examined the influence of the negative stimulus factors on the qualitative performance of the firm. As a result, it was found that source non-expert had the highest effect on skepticism on ad. Also, platform overflow has a direct effect on the evaluation of the website as well as the negative evaluation of the advertisement. Moreover, this study provides concrete implications for the subdivision market by verifying the differences between the paths according to the level of website involvement.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.181-190
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• 2019

Recently, Low impact development techniques, a form of nature-based solutions (NBS), were seen cost-efficient alternatives that can be utilized as alternatives for conventional stormwater management practices. This study evaluated the effectiveness of an infiltration trench (IT) and a small constructed wetland (SCW) in treating urban stormwater runoff. Long-term monitoring data were observed to assess the seasonal performance and cite the advantages and disadvantages of utilizing the facilities. Analyses revealed that the IT has reduced performance during the summer season due to higher runoff volumes that exceeded the facility's storage volume capacity and caused the facility to overflow. On the other hand, the pollutant removal efficiency of the SCW was impacted by the winter season as a result of dormant biological activities. Sediment data also indicated that fine and medium sand particles mostly constituted the trapped sediments in the pretreatment and media zones. Sediments in SCW exhibited a lower COD and TN load due to the phytoremediation and microbiological degradation capabilities of the system. This study presented brief comparison LID facilities equipped with pre-treatment zones. The identified factors that can potentially affect the performance of the systems were also beneficial in establishing metrics on the utilization of similar types of nature-based stormwater management practices.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.313-323
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• 2019

Deep Tunnel system is a large-scale urban flood control facility installed underground in order to reinforce the lack of drainage systems in developed cities. In a structure like a deep tunnel system, the undular bore generated in the downstream causes a problem in the hydraulic stability of the tunnel. In this study, to investigate the influence of the undular bore on the hydraulic stability at the "Shinwol rainwater storage and drainage system", under construction for the first time in the country, a hydraulic model experiment was conducted on various flooding inflow scenarios. As a result of the hydraulic model experiment carried out in this study, the undular bore generated downstream is trapped in the pipe while moving to upstream, pushes the compressed air. It is judged that overflow occurred by choking the vertical drop shaft in the process when this compressed air is being exhaust through the upstream vertical drop shaft and blocking flood inflow. In addition, the analysis of velocity of undular bore shows that the undular bore transfers energy, and at this time, the pressure rose in the pipe and the velocity increment occurred of the undular bore. Further studies are needed to predict the size and velocity of undular bore, which plays an important role in the hydraulic stability of the tunnel in the deep tunnel system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.3
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• pp.381-389
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• 2019

It is important to estimate flood overflow because adverse weather phenomena are frequently occurring in recent years. In order to cope with such abnormal floods, it is essential to perform flood inundation simulations for constructing flood inundation maps as nonstructural countermeasures. However, there is no quantitative evaluation method and criterion for flood inundation prediction. In this study, the Receiver Operation Characteristics (ROC) and Lee Sallee Shape Index (LSSI) were employed to quantitatively evaluate the accuracy of flood inundation maps for 10 administrative districts. Comparing predicted inundation maps with actual inundation trace maps, the ROC score was 0.631 and the LSSI was 25.16 %. Using the ROC and the LSSI, we proposed an evaluation criterion for flood inundation map. The average score was set as an intermediate score and distributed into 5 intervals. The validity of the evaluation criterion was investigated by applying to the XP-SWMM model, which has been verified and corrected. The ROC analysis result was 0.8496 and the LSSI was 51.92 %. It is considered that the proposed evaluation criteria can be applied to flood inundation maps.

• (The)Korea Educational Review
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• v.17 no.3
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• pp.175-240
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• 2011

The purpose of this study is to understand how the perception and attitude in children's education have changed over the 20th century in South Korea by searching the newspaper articles. The modernization in 20th century brought radical changes in every aspect of Korean society including education. As an educational attitude and policies from the government changed, so did the tones reflected in the newspaper articles. To sum up, there were four (4) principal changes found from this study as follows;Firstly, parental involvement and role as an educator became more important in Korean society and huge generation gap arose in attitudes towards children's education and custody. Secondly, the traditional gender-based roles of mothers' with image of love and fathers' with strength disappeared and mothers' responsibility of children's education were more emphasized during 20th century. Meanwhile, today's society is calling for an immediate return of fathers' involvement and commitment to children's education in the household. Thirdly, as the overflow of information and knowledge in 20th society caused an excessive interest in children's education, there were rising demands for establishing proper views and ideas on children's education. Lastly, the responsibilities of children's education which had been laid on household was expanded to public and government, which can be seen from the fact that an educational support from the government was extended to the children of overseas Korean as well as those residing in Korea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.80-86
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• 2024

Large-scale earthquakes are occurring globally, especially in the South Asian crust, which is experiencing a state of tension in the aftermath of the 2011 East Japan Earthquake. Uncertainty and fear regarding the possibility of further seismic activity in the near future have been on the rise in the region. The National Disaster Management Research Institute has previously studied and analyzed the overflow characteristics of a tsunami and the rate of flood forecasting through tsunami numerical simulations of the East Sea of South Korea. However, there is currently a significant lack of research on the Southern Coast tsunamis compared to the East Coast. On the Southern Coast, the tidal difference is between 1~4 m, and the impact of the tides is hard to ignore. Therefore, it is necessary to analyze the impact of the tide propagation characteristics on the tsunami. Occurrence regions that may cradle tsunamis that affect the southern coast region are the Ryukyu Island and Nankai Trough, which are active seafloor fault zones. The Southern Coast has not experienced direct damage from tsunamis before, but since the possibility is always present, further research is required to prepare precautionary measures in the face of a potential event. Therefore, this study numerically simulated a hypothetical tsunami scenario that could impact the southern coast of South Korea. In addition, the tidal wave propagation characteristics that emerge at the shore due to tide and tsunami interactions will be analyzed. This study will be used to prepare for tsunamis that might occur on the southern coast through tsunami hazard and risk analysis.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.2
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• pp.125-132
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• 1990

The authors carried out an experiment to investigate the responsive behavior of sea eel, Astroconger myriaster(BREVOORT) to chemical stimuli. The experimental tank was made in doughnut type by using FRP plates. The channel of tank was divided into three concentric troughs by using perforated plastic plates. The inside trough was used as influent part, the outside one as effluent part, and the middle one as the testing trough in which testing fish may be swimmable. The influent part was radially portioned into 12 sections so as to be 30 degrees of central angle. But a basin of any section in testing trough was diverged in the range of 45 degrees of central angle. The the testing trough are radially divided into eight zones. Water is supplied at the rate of 6.3l per minute from the central water tank set as high as 50cm in the center of doughnut, passed across the influent part, testing trough, effluent part and finally discharged by overflow pipes. The chemical substance to stimulate the sea eel was extracted from mackerel, shad and krill which are used as bait for fishing. The chemical substance was injected into any one of 12 hoses which supplies water from central water tank to the influent part at the rate of 2ml per minute. Sea eels used for the experiment were caught by pot in the coast of Chung-mu and accustomed to the tanks for 5 days before applying them to the experiment. The result obtained are as follows: 1. The rate of time length of sea eel's staying in the stimulated zone, as the extracts of mackerel, shad and krill were given to it, was observed as 7.9%, 30.9% and 11.4% respectively. It means that the extract from shad was the most effective of three in attracting sea eel. 2. To compare the effect of freshness of bait fish, the extracts were prepared from shad just killed, form the 24 hour-lapsed one and from the 48 hour-lasped one after killed. The rate of time length of sea eel's staying in the stimulated zone was 30.9%, 17.1% and 11.3% respectively. It means that the freshness is much effective in attracting olfactory fishes like sea eel.