• Journal of the Korean Geographical Society
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• v.30 no.2
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• pp.103-119
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• 1995

This Paper aims to compare the lower marine terraces distributed from Muckho to Gangneung in the mid-eastern coast of Korean peninsula by the geomorphic method of using characteristies of terrace features and terrace deposits, paleosol, and fossil cryogenic structures, and to estimate the age of the lower marine terraces on the basis of the comparisons of those with the characteristics of thalassostatic terrace in adjacent rivers. The 1ower marine terraces in this area can be classified into two levels, i.e., lower marine terrace I and II surfaces, in desending order, according to the difference of former shoreline altitude. The former shoreline heights of the lowerm marine terrace I and II surfaces are 18m and 10m, respectiveiy. The width of the I surface is broader and distributed more continuousiy than that of II surface. Daejin I surface in Muckho coast, and Myeongju and Anin terrace in Gangneung coast could be classified into the lower marine terrace I surface, and Daejin II surfaCe into II surface. The Surface of ancient shore platform of the lower marine terrace I and II surfaces were weathered, and the color of the terrace deposit ranges from red to reddish brown. And this terrace deposit is covered with slope deposit of Last Glacial or fossil periglacial structures (platy structure and vecicle) of Last Glacial are formed in terrace deposit. These facts indicate that the lower marine terrace I and II surfaces had been formed before the Last Glacial, and then affected by chemical weathering under warm environment, finally followed by cold period. But the deposit of the lower marine terrace I surface is more weathered than that of II surface. And pseudogleyed red soil, which is developed in I but not in II surface, could be judged to have been formed in the Last Interglacial culmination stage (Oxygen isotope stage 5e). Therefore, in terms of the degree of weathering of the terrace deposit and the existence of pseudogleyed red soil, the age of both terrace is thought to be a little different. And the characteristics of the above mentioned II surface are accord with those of thalassostatic terrace formed in middle or late period of the Last Interglacial (5e or 5a). Thus on the basis of above all points, the lower marine terrace I and II surfaces in this area could be seen to have formed in the Last Interglacial culmination stage and middle or late period of the Last Interglacial, respectively. Because the lower mamine terrace I surface is broadry distributed in the eastern coast of Korea nPeninsula, the surface could be used to be a key surface in studying Quaternary marine terraces.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.151-164
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• 2022

According to the records of historical and instrumental earthquakes, the southeastern part of the Korean Peninsula is considered the highest seismic activity area. Owing to recent reports of numerous Quaternary faults along the Yangsan and Ulsan fault zones, paleoseismological studies are being actively conducted in these areas. The study area is located in the central part of the Ulsan fault zone, where the largest number of active faults have been reported. Based on lineament and geomorphic analysis using LiDAR images and aerial photographs, fault-related landforms showing topographic relief were observed and a trench survey was conducted. The trench length 20 m, width 5 m, depth 5 m is located approximately 300 m away to the northeast from the previously reported Malbang fault. From the trench section, we interpreted the geometric and kinematic characteristics of the fault based on the deformed features of the Quaternary sedimentary layers. The attitude of the reverse fault, N26°W/33°NE, is similar to those of the reported faults distributed along the Ulsan fault zone. Although a single apparent displacement of approximately 40 cm has been observed, the true displacement could not be calculated due to the absence of the slickenline on the fault plane. Based on the geochronological results of the cryogenic structure proposed in a previous study, the most recent faulting event has been estimated as being earlier than the late Wurm glaciation. We interpreted the thrust fault system of the study area as an imbrication structure based on the previous studies and the fault geometry obtained in this additional trench. Although several previous investigations including many trench surveys have been conducted, they found limited success in obtaining the information on fault parameters, which could be due to complex characteristics of the reverse fault system. Additional paleoseismic studies will contribute to solving the mentioned problems and the comprehensive fault evolution.

• Korean Journal of Environment and Ecology
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• v.32 no.5
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• pp.486-496
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• 2018

In this study, we have selected Larix kaempferi as a study area in Woraksan National Park for understanding the ion index according to the difference of topography in national parks. We measured the weather and ion at two fixed points, ridge and valley, where the Larix kaempferi dominates in the same ecological structure in Woraksan National Park. The weather measurement results showed the average, maximum, and minimum temperatures of $28.22^{\circ}C$, $29.9^{\circ}C$, and $26.4^{\circ}C$, respectively at the ridge. The average, maximum, and minimum temperatures at the valley were $27.08^{\circ}C$, $27.8^{\circ}C$, and $25.5^{\circ}C$, respectively. The average, maximum, and minimum relatively humidities at the ridge were 67.02%, 75.25%, and 61.95%, respectively. he average, maximum, and minimum relatively humidities at the valley were 69.74%, 76.8%, and 63.75%, respectively. The average, maximum, and minimum amounts of positive ions generated in the ridge was $698.40{\pm}59.80ea/cm^3$, $885.88ea/cm^3$, and $597.88ea/cm^3$, respectively. The average, maximum, and minimum amounts of negative ions generated in the ridge were $736.07{\pm}83.89ea/cm^3$, $934.53ea/cm^3$, and $599.32ea/cm^3$, respectively. The ion index is calculated to be 1.06. The average, maximum, and minimum amounts of positive ions generated in the valley were $1,732.49{\pm}354.08ea/cm^3$, $2,652.10ea/cm^3$, and $1,110.92ea/cm^3$, respectively. The average, maximum, and minimum amounts of negative ions generated in the valley were $1,990.47{\pm}433.57ea/cm^3$, $3,126.75ea/cm^3$, and the minimum value was $1,352.17ea/cm^3$. The ion index is calculated to be 1.16. The difference in the amount of negative ions generated in ridge and valley was $1089.26ea/cm^3$, and the difference of the calculated ion index between the ridge portion and the valley portion was 0.10. The results of this study were provided as the reference weather data of national parks for health management.

• 한국해양학회지
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• v.30 no.3
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• pp.184-196
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• 1995

The line-SW is located in the mouth of Gomso Bay (20 Km long and 5-8 Km wide),west coast of Korea. This area is composed of sand flat, mud flat, sand shoal and chenier, The difference of physical, geological and geomorphic conditions in subenvironments of the bay may control and produce distingtive foraminiferal populations and assemblages. This study investigates whether five a priori subenvironments (five local zonations) in Gomso-Bay tidal flat can be distinguished from each other on the basis of total (living plus dead) foraminiferal assemblages. Seventy-four species (67 benthic; 7 planktonic) were recorded in total assemblages of surface sediments from 10 stations. Ammonia beccarii tepida, Discorbis candeiana, Elphidium etigoense and Eponides nipponicus were most dominant species in living and total assemblages. The relative abundance (%) of living population was high at upper flat and decreased from upper to lower flat. The low percentages of living populations in middle to lower flat are probably influenced by the decreasing reproduction of foraminifera caused by high energy condition and addition of dead species from offshore. The occurence of planktonic foraminifera in middle to lower flat (5.3∼6.6%) indicates introduction of planktonic foraminifera from offshore by storm and/or tidal current. The relatively high numbers of species in lower middle to lower flat are probably caused by a mixing of faunas from these areas and offshore. The high numbers of total individuals per 50 ml of sediment in upper flat indicate that this area is a relatively stable environment where waves and currents are protected by the chenier. Five biofacies of the total foraminiferal assemblages were established on the basis of dominant species (those representing more than 20% of the total assemblages in any station) in the five a priori subenvironments recognized along the Line-SW transect in Gomso-Bay tidal flat. Five biofacies are potentially useful in paleoenvironmental interpretation in late Quaternary Gomso-Bay tidal deposits.

• 한국해양학회지
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• v.30 no.4
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• pp.320-331
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• 1995

The closely spaced cores were analyzed to find detailed reconstruction of paleoenvironments and sealable changes along the Delaware Bay coast. Three areas, Kitts Hummock Beach mars, the St. Jones River marsh, and Bowers marsh near the St. Jones River's mouth, were chosen because these areas are compose of their own geomorphic characteristics and sea-level history. since significance of the stratigraphic correlations was to determine sedimentary fancies and paleoenvironments, multidisciplinary methods such as lithological description, grain-size analysis, organic/inorganic content, water content, mineral composition, botanical analysis, micropaleontological analysis, and /SUP 14/C datings were performed. Five major divisions of marsh environments were recognized in the stratigraphic sections: freshwater marsh, initialfreshwater marsh, slightly brackish marsh, brackish marsh, and salt marsh. Most of the lower part in the stratigraphic sections show freshwater marsh. On the top of this, either brackish marsh or tidal flat/tidal stream was recorded. The pro-Holocene sediments consist of sand, mud, and sandy mud, The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene sediments consist of sand, mud, and sandy mud. The pre-Holocene configuration played an important role for developing the Holocene Paleoenvironmental changes. The irregular configuration of the pre-Holocene surface within short distances permitted the concurrent development of variable environments such as freshwater marsh, brackish marsh or salt marsh at similar elevations. The freshwater marsh in this case was formed in the areas of isolation, so saline-water cannot encroach upon these areas. This complex development of paleoenvironments leads to a difficulty in stratigraphic correlation and interpretation of local relative sea-level changes. The deposition of subsurface sediments was affected by sediment supply, compaction, fluvial activity, biological competition, local tectonics and isostacy, climate and local relative sea-level changes. It was interpreted that the positions in the changes from freshwater environments to brackish environments or ice versa are the turning points of transgressions and regressions. Therefore, multiple transgressions and regressions were identified in the stratigraphic sections of the study area.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.1-22
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• 2012

The classification scheme of estuaries can be divided into two categories: qualitative classification based on geomorphic characteristics and quantitative classification based upon the physical properties of water body. While simple and intuitive scheme of the former is difficult to quantify, the latter is not easy to apply due to the lack of data. A classification scheme based on morphological convergence is very promising because it only requires easily accessible data such as width and depth of channels, as well as it can characterize estuaries in terms of tidal propagation. Thus, this paper examines the classification scheme based on estuarine morphological convergence using depth and width data obtained from 19 major Korean estuaries. Morphological convergence for each estuary was estimated with the estuarine length, width and depth data to get the convergence parameters, which includes the degree of funneling ${\nu}$ and the dimensionless estuarine length $y_0$. The transfer function ${\xi}({\nu},ky)$ is then deduced analytically from 1D depth-integrated hydrodynamic momentum equation and continuity equation for estuarine shapes. Tidal response of each estuary is finally calculated using ${\nu}$, $y_0$ and ${\xi}({\nu},ky)$ for comparison and classification. The 19 Korean estuaries were classified into three groups: tidal amplitude-dominated estuaries with standing wave-like tidal response (group 1), current-dominated estuaries with progressive wave-like tidal response (group 2), and the intermediate group (group 3) between groups 1 and 2. The sensitivity analysis revealed that uncertainties in determining the estuarine length can have a critical effect upon the results of classification, which indicates that the reasonable determination of the estuarine length is of critical importance. Once the estuarine length is feasibly determined, depth-convergence can be neglected without any negative effect on the classification scheme, which has an important ramification on the wide applicability of the classification scheme.