간행물
한국지구과학회지 KCI 등재 The Journal of The Korean Earth Science Society
- 발행기관 한국지구과학회
- 자료유형 학술지
- 간기 격월간
- ISSN 1225-6692 (Print)2287-4518 (Online)
- 수록기간 1979 ~ 2024
- 주제분류 자연과학 > 지구과학 자연과학 분류의 다른 간행물
- 십진분류KDC 450DDC 550
권호리스트/논문검색
제12권 제1호 (1991년 3월) 6건
1.
1991.03
구독 인증기관 무료, 개인회원 유료
The Kongju basin of Cretaceous sedimentary rocks, which is located in the area between Ogcheon fold belt and Gyeonggi massif, is developed by the strike-slip fault and shows elongated rhombic shape trending roughly NE and SW with about 4㎞ in width and 25㎞ in length. Two stripes of ductile shear zone are traced in basement rocks along the boundary of basin. The shear sense of ductile shear zone is suggested to be sinistral. The Cretaceous sedimentary rocks within the Kongju Basin also exhibit deformed state in terms of developments of en-echelon arrayed folds, faults and various kinds of joint systems. The majority of joints is occupied by the fractures whose strikes are approximately normal to the directions of en-echelon arrayed fold axes. The shortening(α^(-1)) of fold system is most pronounced at the central part of the basin and gradually decreases toward both ends of the basin. Both of the strikes of fold axial planes and the azimuths of fold axes change discontinuously to form sigmoidal style of en-echelon arrayed folds. The en-echelon arrayed folds, all plunged towards SW direction, indicate that upper layers of the sedimentary rocks are more distributed in the SW area of the basin than in its NE area. The gravity anomaly around the Kongju basin shows 12∼17 mgal in the outer metamorphic zone and 8∼10 mgal in the basin; and its minimum value occurs in NE-SW direction along the western boundary of the sedimentary basin. The electric resistivity study on both boundaries of the basin shows 200∼300Ω-m in the boundary zone, 500∼600Ω-m in sedimentary rocks, and 1000Ω-m or more in the granite-gneiss region. These values indicate that the east boundary be gentle slope and the west one be steep fracture zone. 'These patterns of geophysical data implicates that the Kongju sedimentary basin should be dipping down to the west.
4,500원
2.
1991.03
구독 인증기관 무료, 개인회원 유료
A slope stability analysis has been done on Daesungri area by a computer program using limit equilibrium (Sarma method,1979). For this study, the authors modified the iteration technique and menu system of the algorithm which has been suggested by Hoek(1986). Sarma method is known as a suitable tool for evaluation of slope failure taking into account the kinematics of sliding blocks, and can be used for analysis of slopes of complex profiles such as circular, non-circular, planar sliding surfaces or any combination of these. The insertion of iteration technique and hydrodynamics in this method is very efficient, and gives an accurate estimate of static factor of safety. The analysis allows to specify different shear strength for each slice side and base, and therefore the submergence of any part of slopes is automatically analysed by taking the coordinates of phreatic surface. This program in combination with those stereographic technique developed by Appfied Geology Division of KIER(Korea Institute of Energy and Resources) in 1988 can be expected to give a useful result into evaluation of slope stability
4,200원
3.
1991.03
구독 인증기관 무료, 개인회원 유료
Enlightenment of the Characteristics of the Yellow Sea Bottom Cold Water and Its Southward Extension
Based on a precise analysis of the long-term(1971-1984) hydrographic and wintertime air temperature data gathered in the middle and southern yellow Sea, and together with other supplimentary data from Gteratures, water characteristics of the Yellow Sea Bottom Cold Water(YSBCW) and its southward extension are reexamined ; the influence of the wintertime air temperature on the YSBCW temperature and on its spatial distribution also discussed. It was found that the hitherto defined water characteristics (T, S) of the YSBCW restrict especially the upper limit of salinity to too lower values compared to the real situation, so they are not adequate to describe the spatial distribution of the water and its southward extension phenomenon. From the present study, the southward extention of the YSBCW through the cold water through west off Chejudo from spring to summer is found highly possible ; it is strongest is April and it can be detected until August. In consequence of such a southward advection of the bottom cold water, the water temperature at 50m depth in the cold water through west off Chejudo shows its lowest values in April, with a mean temperature increase by 0.4℃ only from April to August(compared to 4℃ increase near the axis of the Yellow Sea embayment). The frequently observed cold water mass from the west to the southwest(near 32°N, 126°E)off the island during spring and summer is connected with and influenced profoundly by the bottom cold water from the southern Yellow Sea, showing almost same water. characteristics as those of the latter ; it preserves quite well its wintertime water characteristics until summer. Therefore it seems to be quite reasonable to include this cold water mass(found west to southwest off Chejudo) in the definition of the YSBCW. Here, we have suggested a new definition of the YSBCW : T$lt;12℃, 32.2$lt;S$lt;33.5‰ With this new definition, the spatial distribution of the YSBCW from the offshore of the Shandong peninsula to the southwestern area off Chejudo as well as its southward extension from spring to summer can be adequately described. The wintertime air temperature is one of the most important meteorological factors, controlling the summertime water temperature of the YSBCW and its spatial distribution. In other words, the bottom cold water formed during a severe cold winter exhibits in summer lower temperatures and also wider spatial distribution toward the coasts and to the south than that formed during a mild winter.
4,500원
4.
1991.03
구독 인증기관 무료, 개인회원 유료
Seawater temperature, salinity, dissolved oxygen, nutrients and chlorophyll-a have been studied around Hamduck in the northern part of Cheju Island during July, 1989-July, 1990. In the surface water ranges of water temperature, salinity, dissolved oxygen, nitrate, phospate, silicate and chlorophyll-a have been 13.7-26.5℃, 28.51-34.37‰, 4.47-7.14㎖/ℓ, ND-15.42㎍-at/ℓ, ND-1.47㎍-at/ℓ, 2.33-24.1㎍-at/ℓ, and 0.02-2.24㎎/㎥, respectively. Yearly mean values of the near surface waters(0m-10m)at station 6 show high temperature, nitrate, chlorophyll-a, while the values of dissolved oxygen, phosphate, and silicate were low compared with the other stations. The vertical profiles are likely to show the possibility of upwelling in October and tidal front in July, suggesting high productivity of phytoplankton around St.6. N1P ratio varies from 35 inshore to 15 offshore and from 45 in July to 15 in Ferbruary. These variation patterns are similar to those of water temperature.
4,000원
5.
1991.03
구독 인증기관 무료, 개인회원 유료
A two-dimensional land and sea breeze model has been used for the investigation of the circulation over Cheju Island. The model which has different diffusion coefficients for the heat and for the momentum transfer is subdivided into two layers: the surface layer and Ekman layer. A Z^* coordinate system and non-uniform mesh have been applied for the model simulation. From the model simulation, we were able to conclude that low-level wind was much stronger over Cheju city than over Seoguipo city during sea breeze, and vice versa during land breeze. The sea breeze circulation was distinctive over Seoguipo area, and weak land breeze circulation was seen over Cheju area. Meanwhile sea breeze and land breeze circulations over Cheju and Seoguipo area, respectively, were not found in the model simulation.
4,500원
6.
1991.03
구독 인증기관 무료, 개인회원 유료
Synthetic amethyst grown from hydrothermal method and subsequently irradiated with gamma ray was investigated by polarizing microscopy, emission spectroscopy, atomic absorption spectroscopy, X-ray diffraction electron microscopy, infrared absorption spectroscopy, heating and freezing microscopy, density balance, and optical refractometry. Natural amethysts collected from Sokrisan, Eonyang, and Brazil were also studied to compare their mineralogical and gemmological properties with those of the synthetic counterpart. Synthetic and natural amethysts show exactly or nearly identical properties in specific gravity, refractive index, crystal structure, and chemical composition. In contrast, UV-visible spectrometry and I. R. spectrometry data, solid and fluid inclusion features, and color distribution differ considerably which may be used in differentiating the synthetic from its natural equivalents.
4,000원
