• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.393-400
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• 2011

The mass transport is very complicated at the area which has the macro tide and complex geometry such as Gyeonggi bay. Especially, the long period current has a strong influence on the estuarine ecosystem and the long-term distribution of substances. The long period current is caused by several external forcing, whose unique characteristic varies spatially and temporally. The variation characteristics of long period current is analysed and its generation mechanism is studied. The tidal nonlinear constituents such as overtide and compound tide are generated due to nonlinear interaction and it causes mean sea level setup. The tidal wave propagating up into estuary is transformed rapidly by decrease of cross-sectional area and depth. Therefore the mean sea level is getting rise toward upriver. The high and low tide level is similar between down-river(Incheon) and up-river(Ganghwa) during neap tide when the tidal deformation is decreased. The tidal phase difference between two tidal stations causes a periodic fluctuation of sea level difference. The low water level of Ganghwa station during spring tide does not descend under EL(-)2.5 m, but the low water level of Incheon fall down under EL(-)4.0 m. The variation of tidal range and its sea level are increased during spring tide. It is found that the long period current $M_{sf}$ is quite similar to that of sea level difference between the two tidal stations. It means that the sea surface inclination caused by the spatial difference of tidal deformation is important forcing for the generation of long period current.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.3
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• pp.89-101
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• 2015

Outbreaks of highly pathogenic avian influenza(HPAI) subtype H5N8 have occurred in Korea, January 2014 and it continued more than a year until 2015. And more than 5 million heads of poultry hads been damaged in 196 farms until May 2014. So, we studied the spatial, temporal and spatio-temporal patterns of the HPAI epidemics for understanding the propagation and diffusion characteristics of the 2014 HPAI. The results are expressed using GIS. Throughout the study period three epidemic waves occurred over the time. And outbreaks made three clusters in space. First spatial cluster is adjacent areas of province of Chungcheongbuk-do, Chungcheongnam-do and Gyeonggi -do. Second is Jeonlabuk-do Gomso Bay area. And the last is Naju and Yeongam in Jeollanam-do. Also, most of spatio-temporal clusters were formed in spatially high clustered areas. Especially, in Gomso Bay area space density and spatio-temporal density were concurrent. It means that the effective prevention activity for HPAI was carried out. But there are some exceptional areas such as Chungcheongbuk-do, Chungcheongnam-do, Gyeonggi-do adjacent area. In these areas the outbreak density was high in space but the spatio-temporal cluster was not formed. It means that the HPAI virus was continuing inflow over a long period.

• The Journal of Engineering Geology
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• v.24 no.1
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• pp.9-21
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• 2014

We examined high-resolution seismic data, side scan sonar data, surface sediments, and vibrocore samples from a sand ridge off the western part of Dukjuk-Do in Gyeonggi Bay, with the aim of interpretation of seismic stratigraphy and sedimentary environment. Based on the seismic data, the deposited sands are divided into three sedimentary units. 14C age data indicate that the top sequence (sequence I) formed at 5000-6000 yr BP, when a transgression resulted in strong shifting tides. Analyses of the vibrocore samples indicate that sequence II is a paleo-mudflat layer of intertidal sediments dominated by mud. Sequence III consists of terrestrial sediments that are presumed to have been deposited at the end of the Pleistocene, unconformably overlying the acoustic bedrock and Mesozoic granite. The side scan sonar data indicate that sand waves were formed on the seabed on top of the sand ridge. Generally, this is the direction of $N20^{\circ}E$, which coincides with the direction of tidal flow. Sand ripples occur away from the top of the sand ridge and are distributed homogeneously across a sandy slope. Vibrocore analyses indicate that the surface sediments and core sediments (samples VC-1, -2, and -3) are homogeneous, without any internal structures, and are characterized by a mixture of medium and fine sand (1-$2{\phi}$), respectively.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.1
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• pp.13-29
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• 2021

A 3-D hydrodynamic model is applied in the Han River Estuary system, Gyeonggi Bay, to understand the mechanisms of salt transport. The model run is conducted for 245 days (January 20 to September 20, 2020), including dry and wet seasons. The reproducibility of the model about variation of current velocity and salinity is validated by comparing model results with observation data. The salt transport (FS) is calculated for the northern and southern part of Yeomha channel where salt exchange is active. To analyze the mechanisms of salt transport, FS is decomposed into three components, i.e. advective salt transport derived from river flow (QfS0), diffusive salt transport due to lateral and vertical shear velocity (FE), and tidal oscillatory salt transport due to phase lag between current velocity and salinity (FT). According to the monthly average salt transport, the salt in both dry and wet seasons enters through the southern channel of Ganghwa-do by FT. On the other hand, the salt exits through the eastern channel of Yeongjong-do by QfS0. The salt at Han River Estuary enters towards the upper Han River by FT in dry season, whereas that exits to the open sea by QfS0 in wet season. As a result, mechanisms of salt transport in the Han River Estuary depend on the interaction between QfS0 causing transport to open sea and FT causing transport to the upper Han River.

• Journal of the Korean Institute of Rural Architecture
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• v.10 no.2
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• pp.61-70
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• 2008

The purpose of this study is to give some suggestions for the legal supplement of the regulation on the balcony expansion for the optimal use of apartment balcony. For the purpose, this study focused on the characteristics of spaces expanded to the balcony, in the plans supplied after the legalization of balcony expansion, comparing them by their location; the metropolitan area of Seoul Gyeonggi and the districts of the other areas. The 168 plans of apartments in the supplied by top 10 constructors in the metropolitan areas of Seoul and Gyeonggi, together with the 92 plans in the other smaller districts in 2006 to 2007 were analyzed with the tools of frequency and chi-square analysis. The result is as follows. (1) The region showed no difference in the plans of balcony; whereas the size, the position and access of the shelter explained some differences of balcony plan. (2) In wider plans, balconies were placed in all sides of plan-front, rear and side, and were remodeled to expand facing rooms. (3) The balcony expansion tended to increase the number of bays. (4) In almost cases, the living rooms were expanded to balcony. In smaller plans, the balconies were remodeled to supply supplementary kitchen space, splitting it from laundry. (5) The shelters were placed at the rear or side of plans, but the shelter facing room could be dangerous in case of fire. The balcony expansion, despite of legalization spirit to adopt diverse use of additional spaces for residents' needs, was only a tool for the space expansion. The amendment of the regulation is needed to accommodate these findings that the balconies should be identified by their function, that the front corridor-type balcony should be limited in length and magnitude, and that the shelter should be positioned with easy access.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5826-5834
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• 2014

This paper examined the changes in flow patterns due to a blockage of tidal currents in the sea areas between Incheon North Port and Yeomha Channel when it would be influenced by the construction of the Incheon North Port Yeongjongdo dredged soil dumping ground and Incheon Bay tidal power plant. The numerical simulation was performed for three cases: before and after constructing the Incheon North Port Yeongjongdo dredged soil dumping ground and after the construction of the sea-dyke on the east side of the Incheon Bay tidal power plant. The simulation results showed that the tidal directions and currents velocity were similar before and after the construction of the Yeongjongdo dredged soil dumping ground. After the construction of the East Sea-dyke of Incheon tide power plant, however, the tidal currents patterns changed significantly due to flow blockage toward Gyeonggi Bay. The main flow was formed in the north-south direction, and the tidal currents velocity increased slightly on the downstream areas (A,B,C) of Hodo, which is the entrance of the Ara Waterway. The tidal currents at the mouth(D) of Yeomha Channel decreased significantly. The tidal currents of the west side of Se-eodo and the east side of the sea-dyke were rotary currents. The results of this study will provide basic data for the environmental impact assessment and the operation of the Gyeongin Ara Waterway.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.195-205
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• 2020

Oceanic conditions in walleye pollock habitat in the East Sea have shown decadal fluctuations between warm and cold periods in turn. Specifically, sea surface temperature (SST) has shown a dramatic increase between the late 1980s and the middle 2000s, and abrupt decreasing patterns after the late 2000s. Oceanic conditions in the Dong-han Bay (spawning ground) and middle eastern coastal waters (fishing ground), however, indicated different fluctuation trends in SST, increasing in the Dong-han Bay after the late 1980s, and decreasing after the late 2000s. These fluctuation patterns were especially clear in February and March. Sea surface temperature in the middle eastern coastal waters of Korea soared continuously after the late 1980s, but did not show a distinct decreasing pattern after the late 2000s compared with Dong han Bay, except for February SST values. These long term water temperature changes in both walleye pollock spawning and fishing ground are related to variation in walleye pollock landings. Especially, abrupt changes in spawning ground SST can be one of the factors influencing survival in the early ontogenesis of walleye pollock, including egg and yolk larval stages. During the 1980s, the area of suitable spawning temperature (2-5℃) was wider, and the length of Walleye pollock egg and larval stages greater compared with past and present oceanographic environments. However, such patterns did not correspond with the optimal spawning temperature range and greater length of development of walleye pollock during the late 1980s likely triggering a decline in pollock stock. In conclusion, it has been supposed that the dramatic decrease in walleye pollock landings in the East Sea since the late 1980s was caused by increasing water temperature leading to both early mortality and unsuitable spawning conditions.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.355-364
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• 2022

In this study a tendency of abnormal sea surface temperature (SST) occurrence in the seas around South Korea is analyzed from daily SST data from satellite and 14 buoys from August 2020 to July 2021. As thresholds 28℃ and 4℃ are used to determine marine heatwaves(MHWs) and abnormal low water temperature (ALWT), respectively, because those values are adopted by the National Institute of Fisheries Science for the breaking news of abnormal temperature. In order to calculate frequency of abnormal SST occurrence spatially by using satellite SST, research area was divided into six areas of coast and three open seas. ALWT dominantly appeared over a wide area (7,745 km²) in Gyeonggi Bay for total 94 days and it was also confirmed from buoy temperature showing an occurrence number of 47 days. MHWs tended to be high in frequency in the coastal areas of Chungcheongdo and Jeollabukdo and the south coastal areas while in case of buoy temperature Jupo was the place of high frequency (32 days). This difference was supposed to be due to the low accuracy of satellite SST at the coasts. MHWs are also dominant in offshore waters around Korean Peninsula. Although detecting abnormal SST by using satellite SST has advantage of understanding occurrence from a spatial point of view, we also need to perform detection using buoys to increase detection accuracy along the coast.

• Journal of the Korean Geographical Society
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• v.38 no.5
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• pp.686-700
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• 2003

In Korea, aside from their official administrative names, aliases of each province or some regions are widely used not only today but also during the Joseon period when the provincial system as local administrative system was firmly implemented. Of aliases, the most representative were Giho, Gwandong, Hoseo, Haeseo, Honam, Yaeongnam, Gwanseo, and Gwanbuk representing the eight provinces (precisely, Gyeonggi and seven provinces) of Chosun Dynasty, as well as Yeongdong and Yeongseo that represent the east and the west of Gangwon-do. These aliases are mostly based on topographical features and physiographical elements, and compared to the official names of eight provinces which depended solely on city names. Of aliases, some appeared in literature during 13-l4th centuries, and all provincial aliases seem to have been widely used after the late 15th century. Aliases continued to be used for 500 to over 700 years. Aliases of eight provinces, geographically, played not lesser role than their official names. Aliases of the eight provinces and regions during the Chosun Dynasty that have been handed down are considered as holding their places' cultural and historical backgrounds, and have become important enough to be accepted as a unit of geographical regional division. The origin and meaning of aliases of each province have been partially disclosed to the geographical circle and the general public. However, the details should be reviewed. First of all, Gwan in Gwanbuk, Gwanseo and Gwandong, as well as Yeong in Yeongnam, Yeongdong and Yeongseo, are each considered as meaning Sobaek Mountain Range and Taebaek Mountain Range with many borderline areas (borders) and military strategic hubs. Also, Ho in Honam, Hoseo, and Giho, are considered as based on the Geum River and Eurimji, and Haeseo are considered as meaning the west of the Gyeonggi Bay, and having relevancy with the first letters of Haeju and Seoha (Pungcheon).

• Journal of Environmental Impact Assessment
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• v.19 no.3
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• pp.357-365
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• 2010

This study evaluated current status of marine sand mining and related assessment systems in Korea for supporting effective policy development. The estimated total deposit of sand was ca. 10 billion $m^3$, while the estimated minable amount was ca. 5.5 billion $m^3$, in which marine sand accounted for 21%. The proportion of marine sand to the total mined aggregates has steadily increased by 15% in 1992 to 28% in 2002, but recently slightly decreased. Marine sand mining is regulated under a consultation system on the coastal development according to the "Marine Environmental Management Act". During 2002-2009, a total of 184 million $m^3$ of marine sand was mined, and the annual amount ranged from 17,440,000-33,698,000 $m^3$ the coastal area accounted for 64.5% and the Exclusive Economic Zones (EEZs) 35.5%. In the coastal area, the major area supplying the marine sand was Gyeonggi Bay (>62%) followed by some southwestern coastal areas. The South and the West EEZ explained 23.9% and 11.6% of the total mined sand. The extent of marine sand mining in Korea was evaluated to be greater compared with other countries. Large-scale concentrated and repeated sand mining can damage environmental changes and ecology with long-term accumulated impacts.