• Ocean and Polar Research
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• v.42 no.2
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• pp.97-113
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• 2020

In-situ observations were carried out in April 2015 to investigate the occurrence of water temperature inversion in a region west of Jeju Island. Analysis of in-situ in the western part of Jeju island showed that cold water moved to the southeast from the surface to the middle layer and warm water moved from the middle to the lower layer of the northwest direction. The water temperature inversion occurred at 84 stations (63.1%) out of 133 stations. At the boundary of the water temperature inversion layer, it was formed in the middle layer and disappeared. In the strongly appearing, it started from the middle layer to the lower layer. The shape of the water temperature inversion layer was different. As a result of horizontal water temperature slope analysis of the water temperature inversion zone, maximum 0.23℃/km was obtained and the mean was 0.06℃/km. The role of water temperature inversion as an indicator to determine the formation of water front. As a result of the water mass analysis, Jeju Warm Current Water and Tsushima Warm Current Water of high temperature and high salt intruded from the middle to the bottom. In the middle layer occurred as the Yellow Sea Cold Water of low water temperature and low salinity expanded.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.115-118
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• 2005

Leakage of waterworks pipe line net cause loss of water resources, additional foundation of pressurization facilities from pressure loss and soil weakening near leaked pipe line, etc. This is difficult to maintain and manage waterworks pipe line net and to cause serious economic loss. Rate of accounted water is better by monitoring always water pressure and flux, etc. from isolated region, positively dealing with leakage accident and preventing leakage from occurring. Actually after isolating region, average rate of accounted water in this region is 88.94% by continuously monitering control of water pressure and inflow rate. It is about 9.44% more than that of Busan metropolitan city in 2003, 79.5%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.334-337
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• 2003

The results of this numerical model is usable to analysis for the phenomena of precipitation during the periods of a rainy season in the Northeastern Asia. Case l(start of rainy season) dominates over precipitation by the processing of convection from the equator region through the East China region, and then the most of water vapor is transported by the processing of advection from the India-monsoon region to this study region. Case 2(heavy rainy season) faints precipitation by the processing of convection in the Korean peninsula, but dominates precipitation by the processing of microphysics. the water vapor originates from the India-monsoon region.

• Ocean and Polar Research
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• v.27 no.4
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• pp.433-441
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• 2005

To investigate the characteristics of tidal currents and water circulation in the coastal waters off the Taean Peninsula, tidal currents and sea levels were measured at the study area from 1998 to 2004. In the central waterway to the south of Changan Sand Ridge, mean speed of tidal currents and residual currents were 74.0cm/s, 17.8cm/s respectively; the dominant residual currents flowed northeastward, and the amplitudes of semi-diurnal components $(M_2,\;S_2)$ were larger than diurnal components $(O_1,\;K_1)$. The flood and ebb tidal currents were northeastward and southwestward, respectively, and each period was about 6 hours for them, which was consistent with the period of sea levels at the study area. In the coastal region near Hakampo, Taean, mean velocities of tidal currents and residual currents were 46.1cm/s, 30.8cm/s respectively, and the dominant residual currents flowed southwestward. The amplitudes of shallow water constituents $(M_4,\;MS_4)$ were relatively laige, which were weaker to the northeastern coastal region off Mineodo. The northeastward flow continued for about $2{\sim}3$ hours, while the southwestward flow continued for about $9{\sim}10$ hours near Hakampo during the tidal period. Tidal currents flowed northeastward in the central area of the waterway during the period from the Low Water Level (LWL) to the High Water Level (HWL). While the currents in the coastal region flowed northeastward for the first 3 hours after the LWL, southwestward counter-currents flowed between 3 and 6 hours after the LWL. During the period from the HWL to the LWL, the dominant currents flowed southwestward in the study area except to the northeastern coastal region off Mineodo. Along the shorelines, the counter-currents flowed northward between 4 and 6 hours after the HWL. It seems that the counter-currents near the coastal region are caused by the topography and the geography of the shorelines at the study area.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.163-170
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• 1998

The influence of the dam-reservoir interaction on the seismic response of dams is studied. The impounded water is assumed to be inviscid and compressible ideal fluid. Material damping is introduce to simulate the energy loss of wave propagation in the water. The irregular region of the impounded water adjacent to the dam is modeled by boundary element method. The regular region extending to infinity is modeled by the transmitting boundary. The dam body is assumed to behave elastically and modeled by finite element method. The coupled equation of motion is obtained by substructure method.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.787-794
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• 2018

The various natural disasters such as floods and localized heavy rains are increasing due to the global warming. If a natural disaster can be detected and analyzed in advance and more effectively, it can prevent enormous damage of natural disasters. Recent development in visual sensor technologies has encouraged various studies on monitoring environments including rivers. In this paper, we propose a method to detect water regions from river images which can be exploited for river surveillance systems using video sensor networks. In the proposed method, we first segment a river image finely using the minimum spanning tree algorithm. Then, the seed regions for the river region and the background region are set by using the preliminary information, and each seed region is expanded by merging similar regions to segment the water region from the image. Experimental results show that the proposed method separates the water region from a river image easier and accurately.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1516-1524
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• 2020

Climate change is expected to affect not only availability and quality of water, the valuable resource of human life on Earth, but also ultimately public health issue. A six-year monitoring (total 20 times) of Escherichia coli O157, Salmonella enterica, Legionella pneumophila, Shigella sonnei, Campylobacter jejuni, and Vibrio cholerae was conducted at five raw water sampling sites including two lakes, Hyundo region (Geum River) and two locations near Water Intake Plants of Han River (Guui region) and Nakdong River (Moolgeum region). A total 100 samples of 40 L water were tested. Most of the targeted bacteria were found in 77% of the samples and at least one of the target bacteria was detected (65%). Among all the detected bacteria, E. coli O157 were the most prevalent with a detection frequency of 22%, while S. sonnei was the least prevalent with a detection frequency of 2%. Nearly all the bacteria (except for S. sonnei) were present in samples from Lake Soyang, Lake Juam, and the Moolgeum region in Nakdong River, while C. jejuni was detected in those from the Guui region in Han River. During the six-year sampling period, individual targeted noxious bacteria in water samples exhibited seasonal patterns in their occurrence that were different from the indicator bacteria levels in the water samples. The fact that they were detected in the five Korea's representative water environments make it necessary to establish the chemical and biological analysis for noxious bacteria and sophisticated management systems in response to climate change.

• Journal of the Korean association of regional geographers
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• v.7 no.4
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• pp.146-164
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• 2001

The purpose of this paper is to outline a research agenda for the evaluation of the sustainability of freshwater policies, especially as they relate to large cities in the Asia-Pacific region, and to co-work a comparative study on the cases of Seoul and Sydney on the basis of the research agenda. The overall long-tenn aim of the present research is to develop a framework for sustainable urban freshwater policy in the Asia-Pacific region. The nature of freshwater policies for a sample of 16 large cities in the Asia-Pacific region will be critically evaluated for 5 years in the future. For the purposes of this research agenda, four main types of urban water conflict have been evaluated - jurisdictional conflicts, conflicts related to accessibility, sectoral conflicts and environmental conflicts. Of course, in reality, aspects of these four types of conflict invariably overlap. In the case study, the environmental conflict over fresh water of Seoul can be seen as a jurisdictional, sectoral and accessibility-related conflict between the central government and Seoul local government which want to regulate the lan-use with the water conservation zone around the Paldang Dam located at a upstream of the Han River on the hand, and the Yangpyong local governmant and its population within the conservation zone which have struggled against such a regulation, on the other. In the case study on the Sydeny water crisis in 1998, the environmental conflict over fresh water of Sydney in Australia can be seen as a jurisdictional conflict between the State government and the Sydney local government and the corporatized Sydney Water which have been responsible to supply fresh water on the one hand, and the Sydney population who have been suffered from the contaminated water, on the other. Over the past ten years, both globally and in the Asia-Pacific region, including in S. Korea and Australia, the concept of sustainable development has taken on a growing role in the determination of environmental policy. The balance for sustainable policy would be between the requirement to augment water supply to cope with projected future demands and the need to improve efficiency of water use.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.969-970
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• 2005

• Water Engineering Research
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• v.5 no.3
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• pp.123-131
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• 2004

This paper describes the use of spatial interpolation for estimating seasonal crop potential evapotranspiration (PET) and irrigation water requirement in unmeasured evaporation gage stations within Edwards Aquifer, Texas using GIS. The Edwards Aquifer area has insufficient data with short observed records and rare gage stations, then, the investigation of data for determining of irrigation water requirement is difficult. This research shows that spatial interpolation techniques can be used for creating more accurate PET data in unmeasured region, because PET data are important parameter to estimate irrigation water requirement. Recently, many researchers are investigating intensively these techniques based upon mathematical and statistical theories. Especially, three techniques have well been used: Inverse Distance Weighting (IDW), spline, and kriging (simple, ordinary and universal). In conclusion, the result of this study (Table 1) shows the kriging interpolation technique is found to be the best method for prediction of unmeasured PET in Edwards aquifer, Texas.