• Korean Journal of Remote Sensing
• /
• v.37 no.6_1
• /
• pp.1589-1597
• /
• 2021

Submarine groundwater discharge (SGD) in coastal areas is gaining importance as a major transport route that bring nutrients and trace metals into the ocean. This paper describes the analysis of the seasonal changes and spatiotemporal characteristicsthrough the modeling monthly SGD for 35 years from 1986 to 2020 for the Nakdong river basin. In this study, we extracted 210 watersheds and SGD estimation points using the SRTM (Shuttle Radar Topography Mission) DEM (Digital Elevation Model). The average annual SGD of the Nakdong River basin was estimated to be 466.7 m²/yr from the FLDAS (Famine Early Warning Systems Network Land Data Assimilation System) recharge data of 10 km which is the highest resolution global model applicable to Korea. There was no significant time-series variation of SGD in the Nakdong river basin, but the concentrated period of SGD was expanded from summer to autumn. In addition, it was confirmed that there is a large amount of SGD regardless of the season in coastal area nearby large rivers, and the trend has slightly increased since the 1980s. The characteristics are considered to be related to the change in the major precipitation period in the study area, and spatially it is due to the high baseflow-groundwater in the vicinity of large rivers. This study is a precedentstudy that presents a modeling technique to explore the characteristics of SGD in Korea, and is expected to be useful as foundational information for coastal management and evaluating the impact of SGD to the ocean.

• The Journal of the Korea Contents Association
• /
• v.9 no.12
• /
• pp.448-458
• /
• 2009

This study suggested speech generation device(SGD) program to materialize the proper communication aids which address to language abilities by students with cerebral palsy in the stage of word recognition achievement. This SGD program aim at function of learning mediation and communication expression by synchronization not restrict aim of AAC aids' employment to the only function of communication expression. And this SGD was designed to evaluate language abilities of student with cerebral palsy through analysis of the date offered at this program, and then might utilize to set learning goals and objects, modify teaching contents. This SGD program have a meaning on contribution to possible teaching the user AAC aids, students with cerebral palsy by whole language approach in natural environment but in artificial situation at script.

• The Journal of the Acoustical Society of Korea
• /
• v.39 no.6
• /
• pp.505-514
• /
• 2020

Since a large amount of training data is typically needed to train Deep Neural Networks (DNNs), a parallel training approach is required to train the DNNs. The Stochastic Gradient Descent (SGD) algorithm is one of the most widely used methods to train the DNNs. However, since the SGD is an inherently sequential process, it requires some sort of approximation schemes to parallelize the SGD algorithm. In this paper, we review various efforts on parallelizing the SGD algorithm, and analyze the computational overhead, communication overhead, and the effects of the approximations.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.15 no.4
• /
• pp.192-202
• /
• 2010

Submarine groundwater discharge (SGD) has been recognized as a provider for freshwater, nutrients, and dissolved constituents from continents to the oceans and paid more attention with regard to the mass balance of water or dissolved constituents on local and global scales. The submarine discharge of fresh groundwater (fresh SGD) through seepage or springs in coastal ocean may be especially important in aspects of water resource and marine environment managements in the future. Based on the worldwide compilations of observed fresh SGD, our review reveals that fresh SGD occurs in various marine environments along most shoreline of the world and the global estimates of fresh SGD were approximately 0.01-17% of surface runoff. In addition, the input of fresh SGD calculated and investigated in this study were about 50%, 57%, 89%, and 420% of total river discharge in Jeju Island, Yeongil Bay, Masan Bay, and Yeoja Bay, respectively. These inputs from fresh SGD along the shoreline of Korea Peninsula are much higher than those of the whole world, greatly vary with the region. However, since these estimates are based on the water balance method mainly used in coastal ocean, we have to perform continuous monitoring of various parameters, such as precipitation, tide, evapotanspiration and water residence time, which have an impact on the water balance in a lot of areas for evaluating the precise input of fresh SGD. In addition, since the method estimating the input of fresh SGD has brought up many problems, it is required to make an intercomparison between various methods such as hydrogeological assumption, numerical modeling, and seepage meter.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.8
• /
• pp.861-866
• /
• 2015

This study was aimed to detect area of Submaine Groundwater Discharged(: SGD) around Jeju island using by remote sensing. Sea Surface Temperature(SST) was identified using IR camera on Unmaned Aerial Vehicle(UAV) at Gimnyeong port in study area. Then SGD location was detected by comparing range of SGD temperature. Generally, range of SGD temperature is distributed 15 to 17 like underground water. The result, SGD location was detected by SST distribution of Gimnyeong port recorded by IR camera in the southwest of study area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.17 no.4
• /
• pp.252-261
• /
• 2012

To determine the temporal variations of submarine groundwater discharge (SGD) and SGD-driven nutrients inputs, we measured the seepage rate and the nutrient concentrations of pore water/groundwater in Bangdu Bay of Jeju Island at two and three month intervals from September 2009 to September 2010. The seepage rate of groundwater ranged from 0 to 330 cm/day (average ~170 cm/day) during the five sampling periods, which increased sharply from high tide to low tide due to changes in hydraulic pressure gradient between water table in land and water sea level in the coastal ocean by the tidal cycles. The submarine inputs of groundwater were also relatively higher in summer than in winter. The nutrient fluxes from SGD were about 90~100%, 70~95%, and 65~100% of the total input (except from open ocean waters) for dissolved inorganic nitrogen (DIN), phosphorus (DIP), and silicate (DSi), respectively, potentially supporting about 0.9~33 g $carbon/m^2/day$ of new primary production in Baugdu Bay. Thus, our study suggests that SGD-driven nutrients may play an important role in the eutrophication and biological production in the coastal ocean of Jeju Island.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.10 no.4
• /
• pp.204-212
• /
• 2005

Recognition has emerged that nutrient inputs from the submarine discharge of fresh, brackish, and marine groundwaters into the coastal ocean are comparable to the inputs via river discharge. The coastal areas of the Korea peninsula and adjacent seas exhibit particular importance in the role of submarine groundwater discharge (SGD), in terms of the magnitude of SGD and associated continental material fluxes. For example, in the southern sea of Korea, SGD transports excess nutrients into the coastal regions and thus appears to influence ecosystem changes such as the outbreak of red tides. Around volcanic island, Jeju, which is composed of high permeability rocks, the amount of SGD is higher by orders of magnitude relative to the eastern coast of North America where extensive SGD studies have been conducted. In particular, nutrient discharge through SGD exerts a significant control on coastal ecosystem changes and results in benthic eutrophication in semi-enclosed Bang-du bay, Jeju. In the entire area of the Yellow Sea, tile submarine discharge of brackish groundwater and associated nutrients are found to rival the river discharges into the Yellow Sea, including those through Yangtze River, Han River, etc. In the eastern coast of the Korea peninsula, SGD is significantly higher during summer than winter due to high hydraulic gradients and due to wide distribution of high permeability sandy zones, faults, and fractures. On the other hand, in the estuarine water, downstream construction of the dam in the Nakdong River, SGD was highest when the river discharge was lowest (but water level of the dam was highest). This suggests that even though there is no visible freshwater discharge into this estuary, the discharge of chemical species is significant through SGD. On the basis of the results obtained from the coastal areas of the Korea peninsula, SGD is considered to be an important pathway of continental contaminants influencing tidal-flat ecosystems, red tides, and coral ecology. Thus, future costal management should pay great attention to the impact of SGD on coastal pollution and eutrophication.

• Economic and Environmental Geology
• /
• v.38 no.4 s.173
• /
• pp.395-409
• /
• 2005

To explore submarine groundwater discharge (SGD) into the coastal zone of Jeju Island, the water quality analysis with seasonal remotely sensed data was carried out. If the groundwater is directly discharged into the ocean, the water quality of coastal zone is influenced. Therefore sea surface temperature (SST), the transparency, and Chlorophyll-a's concentration were analyzed for extracting the anomaly zone related with SGD using Landsat Thematic Mapper (TM) data acquired on April, August, and December. Then the spatial characteristics of springs, which located along the coastal area, were analyzed by CIS data integration based on Fuzzy logic. The integration results were compared with the anomaly zone extracted from Landsat TM data, and it is considered that springs has close relationship with SGD.

• The Journal of the Korea Contents Association
• /
• v.8 no.6
• /
• pp.74-81
• /
• 2008

Protein interaction network contains a small number of highly connected protein, denoted hub and many destitutely connected proteins. Recently, several studies described that a hub protein is more likely to be essential than a non-hub protein. This phenomenon called as a centrality-lethality rule. This nile is widely credited to exhibit the importance of hub proteins in the complex network and the significance of network architecture as well. To confirm whether the rule is accurate, we Investigated all protein interaction DBs of yeast in the public sites such as Uetz, Ito, MIPS, DIP, SGB, and BioGRID. Interestingly, the protein network shows that the rule is correct in lower scale DBs (e.g., Uetz, Ito, and DIP) but is not correct in higher scale DBs (e.g., SGD and BioGRID). We are now analyzing the features of networks obtained from the SGD and BioGRD and comparing those of network from the DIP.

• Proceedings of the Korea Contents Association Conference
• /
• 2008.05a
• /
• pp.842-845
• /
• 2008

The protein interaction network contains a small number of highly connected protein, denoted hub and many destitutely connected proteins. Recently, several studies described that a hub protein is more likely to be essential than a non-hub protein. This phenomenon called as the centrality-lethality rule. This rule is widely credited to exhibit the importance of hub proteins in the complex network and the significance of network architecture as well. To confirm whether the rule is accurate, we investigated all protein interaction DBs of yeast in the public sites such as Uetz, Ito, MIPS, DIP, SGD, and BioGRID. Interestingly, the protein network shows that the rule is correct in lower scale DBs (e.g., Uetz, Ito, and DIP) but is not correct in higher scale DBs (e.g., SGD and BioGRID). We are now analyzing the features of networks obtained from the SGD and BioGRD and comparing those of network from the DIP.