• Journal of the Korean Geographical Society
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• v.42 no.3 s.120
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• pp.368-387
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• 2007

In order to explain geomorphological characteristics of the Korean Peninsula, it is necessary to understand the spatial distribution of tectonic movements and its causes. Even though geomorphological elements which might have been formed by tectonic movements(e.g. tilted overall landform, erosion surface, river terrace, marine terraces, etc.) have long been considered as main geomorphological research topics in Korea, the knowledge on the spatial distribution of tectonic movement is still limited. This research aims to identify the spatial distributions of tectonic movement via sequential analyses of Digital Elevation Model(DEM). This paper first developed a set of terrain analysis techniques derived from theoretical interrelationships between tectonic uplifts and landsurface denudation processes. The terrain analyses used in this research assume that elevations along major drainage basin divides might preserve original landsurfaces(psuedo-landsuface) that were formed by tectonic movement with relatively little influence by denudation processes. Psuedo-landsurfaces derived from a DEM show clear spatial distribution patterns with distinct directional alignments. Lines connecting psuedo-landsufaces in a certain direction are defined as psuedo-landsurface axes, which are again categorized into two groups: the first is uplift psuedo-landsurface axes that indicate the axis of landmass uplift; and the second is denudational psuedo-landsurface axes that cross step-shaped pusedo-landsurfaces formed via surface denudation. In total, 13 axes of pusedo-landsurface are identified in the Korean Peninsula, which show distinct direction, length, and relative uplift rate. Judging from the distribution of psudo-landsurfaces and their axes, it is concluded that the Korean Peninsula ran be divided into four tectonic regions, which are named as the Northern Tectonic Region, Center Tectonic Region, Southern Tectonic Region, and East Sea Tectonic Region, respectively. The Northern Tectonic Region had experienced a regional uplift centered at the Kaema plateau, and the rate of uplift gradually decreased toward southern, western and eastern directions. The Center Tectonic Region shows an arch-shaped uplift. Its uplift rate is the highest along the East Sea and the rate decreases towards the Yellow sea. The Southern Tectonic Region shows an asymmetric uplift centered a line connecting Dukyu and Jiri Mountains in the middle of the region. The eastern side of the Southern Regions shows higher uplift rate than that of the western side. The East Sea Tectonic Region includes south-eastern coastal area of the peninsula and Gilju-Myeongchun Jigudae, which shows relatively recent tectonic movements in Korea. Since this research visualizes the spatial heterogeneity of long-term tenonic movement in the Korean peninsula, this would provide valuable basic information on long-term and regional differences of geomorphological evolutionary processes and regional geomorphological differences of the Korean Peninsula.

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.27-40
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• 2017

This study tries to analyze topographic distribution and characteristics of as well as formative age and incision rate of fluvial terraces in Danyang River on western side and Geum River on eastern side of the northern Sobaek Mountains and to estimate geomorphic development during the late Quaternary in the mountains regarded as one of the uplift axes in the Korean Peninsula. OSL age dating shows that the fluvial terrace I with an altitude above riverbed of approximately 7~13 m in Danyang River has a formative age of approximately 18 ka (MIS 2) and incision rate in the river is approximately 0.156~0.194 m/ka based on the age. Altitudes above riverbed of the fluvial terrace I in Geum River range from approximately 7 to 14 m and the terrace is thought to be older than 70 ka based on age result from aeolian sediments above the terrace deposits, suggestive of an incision rate less than approximately 0.10 m/ka. These results indicate lower uplift rate in the northern Sobaek Mountains than in the Taebaek Mountains. Moreover, it can be suggested that the northern Sobaek Mountains has experienced asymmetric uplift during the late Quaternary, because the river on western side of the northern Sobaek Mountains shows greater uplift rate than the eastern side river does. Low incision rate in Geum River can be attributed to low altitude of the river basin with little difference in altitude from the base level as well as to gentle river slope due to influence of Nakdong River.

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.15-25
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• 2017

Subi basin is located at the crestline of Taebaek mountains. This paper aims to elucidate the geomorphic development of Subi basin through the analysis of river terraces built in Wangpi-cheon and Banbyeon-cheon. Wangpi-cheon flows northeastward from Subi basin, and Banbyeon-cheon flows southward at the west of Subi basin. Absolute age of terrace is measured by means of OSL methodology, long profile of Wangpi-cheon is made up with 10m interval contour line, and the elevation above river bed of high terraces is measured at the end part of terrace. The results are as follow: Firstly, high river terraces of Subi basin, Wangpi-cheon and Banbyeon-cheon are formed about 40 kyr(MIS 3) being interstadial stage of last glacial period. Secondly, the elevation above river bed of high terraces of Wangpi-cheon and Banbyeon-cheon tends to increase toward upstream. It means that the uplift of Taebaek Mountains influences considerably the formation of their terraces. Thirdly, the elevation above river bed of high terraces at the reach from Seomchon to Suha-ri of Wangpi-cheon tends to decrease toward upstream. This section is captured from Banbyeon-cheon flowing in the opposite direction. River piracy has occurred from the time of formation of Suha-ri high terrace to the time of formation of Hantee wind gap. Finally, for fluvial system of Wangpi-cheon to establish dynamic equilibrium, topographic axis will move toward Banbyeon-cheon.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.413-422
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• 2022

Barnea manilensis is a bivalve which bores soft rocks, such as, limestone or mudstone in the low intertidal zone. They make burrows which have narrow entrances and wide interiors and live in these burrows for a lifetime. In this study, the morphology and the microstructure of the valve of rock-boring clam B. manilensis were observed using a stereoscopic microscope and FE-SEM, respectively. The chemical composition of specific part of the valve was assessed by energy dispersive X-ray spectroscopy (EDS) analysis. 3D modeling and structural dynamic analysis were used to simulate the boring behavior of B. manilensis. Microscopy results showed that the valve was asymmetric with plow-like spikes which were located on the anterior surface of the valve and were distributed in a specific direction. The anterior parts of the valve were thicker than the posterior parts. EDS results indicated that the valve mainly consisted of calcium carbonate, while metal elements, such as, Al, Si, Mn, Fe, and Mg were detected on the outer surface of the anterior spikes. It was assumed that the metal elements increased the strength of the valve, thus helping the B. manilensis to bore sediment. The simulation showed that spikes located on the anterior part of the valve received a load at all angles. It was suggested that the anterior part of the shell received the load while drilling rocks. The boring mechanism using the amorphous valve of B. manilensis is expected to be used as basic data to devise an efficient drilling mechanism.

• Journal of Oral Medicine and Pain
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• v.24 no.2
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• pp.171-179
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• 1999

The authors experienced a oral carcinoma involving the medial cortex of the right ramus of mandible and the left side of the maxilla which was metastasized from primary rectal adenocarcinoma based on the comprehensive evaluation of data obtained from (1) the past medical history of primary rectal adenocarcinoma, (2) the computerized tomographic views of the homogeneous mass on the anteromedial region of the right ramus of mandible destructing the medial cortex of the right ramus of mandible, and the irregular mass around the clivus spreading into the sphenoid sinus and destructing the left side of the maxilla ; the bone scanning of hot spots on the nasal region and the left side of maxilla ; the posteroanterior chest radiographic view of multiple nodular radiopacities on the lung, (3) the retrospective review of the sonographic view of a hypoechoic, well-demarcated, target-like mass with central hyperechoic focus on right lobe of liver in a Korean female of 49-year-old who complained the ptosis of left eyelid, the swelling on left zygomatic area, the left facial paralysis, the facial asymmetry and a round-shaped, elevated lesion with a hematoma on the mucosa covering the right ramus of mandible.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.235-253
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• 2006

We interpreted marine seismic profiles in conjunction with swath bathymetric and magnetic data to investigate rifting to breakup processes at the Korean margin leading to the separation of the Japan Arc. The Korean margin is rimmed by fundamental elements of rift architecture comprizing a seaward succession of a rift basin and an uplifted rift flank passing into the slope, typical of a passive continental margin. In the northern part, rifting occurred in the Korea Plateau, a continental fragment extended and partially segmented from the Korean Peninsula, that provided a relatively broader zone of extension resulting in a number of rifts. Two distinguished rift basins (Onnuri and Bandal Basins) in the Korea Plateau we bounded by major synthetic and smaller antithetic faults, creating wide and symmetric profiles. The large-offset border fault zones of these basins have convex dip slopes and demonstrate a zig-zag arrangement along strike. In contrast, the southern margin is engraved along its length with a single narrow rift basin (Hupo Basin) that is an elongated asymmetric half-graben. Rifting at the Korean margin was primarily controlled by normal faulting resulting from extension in the west and southeast directions orthogonal to the inferred line of breakup along the base of the slope rather than strike-slip deformation. Although rifting involved no significant volcanism, the inception of sea floor spreading documents a pronounced volcanic phase which seems to reflect slab-induced asthenospheric upwelling as well as rift-induced convection particularly in the narrow southern margin. We suggest that structural and igneous evolution of the Korean margin can be explained by the processes occurring at the passive continental margin with magmatism intensified by asthenospheric upwelling in a back-arc setting.