• Economic and Environmental Geology
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• v.53 no.5
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• pp.597-608
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• 2020

Even after the Gyeongju earthquake and the Pohang earthquake, hundreds of aftershocks and micro-earthquakes are still occurring in the southeastern part of the Korean Peninsula. These phenomena mean that the stress is constantly working, implying that another huge earthquake may occur in the future. Therefore, the gravity field interpretation method was used to analyze the deep geological structure of the Pohang-Ulsan region in the southeastern Korean Peninsula. First, a gravity survey was performed to collect the insufficient data and to calculate the detailed Bouguer gravity anomaly in the study area. Based on the gravity anomaly data, the location, direction, and maximum depth of deep fault lines were analyzed using the inversion methods "Curvature analysis" and "Euler deconvolution method". As a result, it is interpreted that at least six fault lines(C1~C6) exist in deep depth. The deep fault line C1 is well correlated to the Yeonil Tectonic Line(YTL), suggesting that YTL is extended up to about 4000m deep. The deep fault line C2 consists of several segment faults and well correlated to the fault lines on the surface. Inferred fault lines C3, C4, and C5 have an NW-SE direction, which is parallel to the Ulsan fault. The deep fault line C6 has the direction of NE-SW, and it is interpreted that the eastern boundary fault of Eoil Basin is extended to the deep. Comparing the inferred fault lines with the distribution of micro-earthquakes, the location of the deep fault line C1 is well correlated to the hypocenter of micro-earthquakes. This implies that faults in deep depth are related to the recent earthquakes in the southeastern Korean Peninsula.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.6
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• pp.417-424
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• 1990

Effect of physical processes on the surface distributions of chlorophyll-a and nutrients was investigated in the southern sea of Korea during summer season. The northwestern area of Cheju Island had higher concentrations of the chlorophyll-a and nutrients than its southeastern area. A nutrient-rich patch was observed in the western area of Cheju Island and the northern area of $34^{\circ}N$ respectively. It seems that the patch in the western area of Cheju Island is formed by horizontal extension of the low-saline Coastal Water of China Contiental(CWCC), while the patch in the northern area of $34^{\circ}N$ by vertical mixing. Also, the high chlorophyll-a in the vicinity of Cheju Island appears to be ascribed to sufficient supply of nutrient from bottom water by coastal upwelling.

• Economic and Environmental Geology
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• v.18 no.4
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• pp.381-397
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• 1985

A petrological study has been done in the pyeongchang-Jaecheon area which is a northwestern part of the basement of Ogcheon zone for the purpose of comparison of the area to the Nogjeon-Yeongchun area which is the antipodal basement of the zone in the petrological and geotectonical view points. The major units of the area are Precambrian granitic gneissic complex, banded gneiss, linea ted leucocratic gneiss and pegmatitic leucogranitic gneiss in the west, elongated exposure of quartz schist (or partly quartzite) and phyllite, named as Jungdaegal-bong Group correlated to the lower sequence of Joseon Group, in the middle, and limestone and calcic dolomite, Iptanri Formation, correlated to the middle of Joseon Group in the east. Igneous plutons are distributed in the areas of gneissic complex and limestone formation as well as in the Eosangcheon and Daedaeri areas in the southeastern out of the area. Present study reveals that the gneissic complex are the products of granitization to metamorphism of amphibolite facies in the order of above mentioned from the metasediments of schists and calcareous rocks. A notable characteristics of the phyllite of Jungdaegal-bong Group is the presence of syntectonically segregated quartz rods in the forms of lens, swirl or boudinage in evenly distributed in the phyllitic to chloritic matrix. Igneous rocks range in composition from gabbro through diorite, granodiorite, to schistosed and porphyritic granites in stock and dike. The orogenic movement of the Ogcheon zone initiated in the middle Proterozoic time, pre-sedimentation of Ogcheon Group and superposed the granitization in Permian, Jurassic Daebo orogeny with granitic batholiths and stocks, and Cretaceous plutonic intrusion.

• Journal of Urban Science
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• v.9 no.2
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• pp.21-30
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• 2020

The purpose of this study is to present a plan to distinguish 229 local governments nationwide by taking into account various characteristics such as population, employment, housing, and industry of the region for customized urban policies in the era of metropolitan areas. The National Statistical Portal (KOSIS) collected and standardized data related to population, housing, industry, and finance by region from 2000 to 2015 for the classification of regional types necessary for customized urban policies, and this was used to classify them into regional types that considered population, employment, housing and industry. The summary of the analysis results is as follows. First, as a result of the regional type classification, 10 key employment sites (4.4%), 5 employment centers (2.2%), 38 residential centers (16.6%), 20 growth areas (8.7%), 26 industrial cities (11.4%), 35 low-fertile farming and fishing villages (15.3%) and 95 stagnant areas (41.5%). Second, the Seoul metropolitan area is the most diverse type of metropolitan area in the country, with most of its core employment sites inside Seoul, residential centers inside and outside Seoul, and growth areas in the southeastern part of the country (Busan, Ulsan, and Gyeongsangnam-do) are mixed with industrial and growth areas centered around Busan, Ulsan and surrounding areas, while the rest of the local governments are found to be low-fertile farming villages or stagnant areas. Daegu (Daegu, Gyeongbuk) is an industrial city in Daegu, and the rest of the local governments are either low-density farming and fishing villages or stagnant areas. The Honam region (Gwangju and Jeolla) was found to be a low-mill farming and fishing village or stagnant area except for Gwangju, while the Chungcheong region (Daejeon, Sejong, and Chungcheong) was seen as a growth area with areas adjacent to Daejeon, Sejong, and the Seoul metropolitan area, and some industrial cities were included. Finally, the Gangwon area was mostly classified as low-density farming and fishing villages and stagnant areas.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.674-677
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• 2005

The characteristics of geothermal resources in Korea was roughly estimated using hot springs, 580 geothermal gradients and 338 heat flow data. In the aspect of hot springs with geologic structure, location of hot springs coincide with fault zone, especially younger age of Cretaceous to Tertiary. In the aspect of geothermal gradients, Pohang area shows the highest geothermal gradient anomaly, which is covered with unconsol idated rock of low thermal conductivity preserving the residual heat from igneous activity or radioactivity elements decay. In the aspect of heat flow density, high anomaly can be found along the zone connecting Uljin-Pohang-Busan on the southeastern part of Korean peninsula at which big fault zone as Yangsan fault is well developed.

• Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.111-117
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• 2011

The population dynamics of Pandalus gracilis was investigated in the southeastern coastal area of Korea between May 1998 and April 2000. Of the 4,127 specimens, 57% were identified as females, 39% as males, and 4% as transitional hermaphrodites. The number of females was greater than that of males and transexuals. A significant correlation was observed between the number of transitional hermaphrodites and ambient seawater temperature. Growth parameters were estimated using the modified von Bertalanffy growth function model incorporating seasonal variation in growth using the program ELEFAN. Females grew faster and reached a larger size-at-age than males (K=0.65/y and $L_{\infty}$=17.86 mm carapace length [CL] for females; K=0.51/y and $L_{\infty}$=14.70 mm CL for males). Mean size and age (95% confidence limits) at sex transition, calculated from growth parameters, were 7.07 mm carapace length and 1.05 years, respectively. The reproductive strategies of pandalid shrimps are discussed in terms of the type of sex transition.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.417-419
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• 2005

This paper presents the effects and the regional power distribution of an increase or a decrease of a power reserve by load flow calculations under seasonal load patterns of each country for the future power shortages faced by the metropolitan areas or by the southeastern area of the South Korea in North-East Asia. In these connections, the types of a power transmission for interconnection consist of the 765kV HVAC and the HVDC. In this paper, the various cases of the power system interconnections in Far-East Asia are presented, and the resulting interconnected power systems are simulated by means of a power flow analysis performed with the PSS/E 28 version tool. The power flow map is drawn from data simulated and the comparative study is done. In this future, a power flow analysis will be considered to reflect the effects of seasonal power exchanges And the plan of assumed scenarios will be considered with maximum or minimum power exchanges during summer or winter in North-East Asia countries.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.11-18
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• 2002

The Ulsan fault with NNW-SSE strike is a very wide and long lineament about 50km along Gyeungju-Ulsan line in the southeastern part of Korea. According to previous studies the Ulsan fault was not considered as a fault but only long lineament since no displacement was found along the lineament. Recently several Quaternary faults were reported in the northeastern part of lineament, which implies the neotectonic movement in this area. We analysed drainage pattern and stream gradient using the DEM (Digital Elevation Model) data for both side of Ulsan fault line to check the recent topographic changes which indicate neotectonic movement. The result shows that stream index in the eastern part of Ulsan fault is higher than the one in the western part. This means that recent tectonic movement is more active in the eastern part of Ulsan fault.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.497-500
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• 2003

If ground water levels of a confined fractured rock aquifer fluctuate with sea tides, individual values of hydrogeologic parameters can be determined. Tidal efficiency and time lag are first calculated from the water level data recorded at an observation device situated inland from the sea. The tidal efficiency factor of the aquifer at the seacoast is then determined from the observation in monitoring wells and used to calculate storage coefficient. Tidal efficiency factor and the tidal time lag are utilized to calculate storage coefficient and the results are compared. This method is tested in the southeastern coastal area of Busan, Korea. This is a simple and inexpensive way to test confined aquifer but the analysis should be performed according to the coastal environment.

• 한국해양학회지
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• v.19 no.1
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• pp.24-30
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• 1984

A numerical experiment was carried out on thee wind-induced coastal upwelling along the east coast of Korea. Only the variability in coastline geometry is considered and an attempt is made to correlate it with the observation previously performed. In order to approximate the coastline geometry as closely as possible, the finite element method with linear triangular grid is employed. Among several fixed locations of upwelling center found in the model, the one in the southeastern coastal area seems to be just what has been observed most frequently.