• Economic and Environmental Geology
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• v.50 no.6
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• pp.477-486
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• 2017

In this study, we analyze precise seabed geomorphology and conditions for comparing the nearshore areas of the Dongdo(East Island) and the Seodo(West Island) using detailed bathymetry data and seafloor backscattering images, in Dokdo, the East Sea. We have been obtained the detailed bathymetry data and the seafloor backscattering data. The survey range is about $250m{\times}250m$ including land of islets to the nearshore areas of the southern part of the Dongdo and the Seodo. As a result of bathymetry survey, the southern area of the Dongdo(~50 m) is deeper than the Seodo(~30 m) in the water depth. The survey areas are consist of extended bedrocks from land of the Dongdo and the Seodo. The underwater rock region of the Seodo is larger than the Dongdo. In spite of similar extended rocks features from islets, there are some distinctive seabed characteristics between the southern nearshore areas of the Dongdo and the Seodo. The Talus-shaped seafloor environment formed by gravel and underwater rocks originating from the land of the Dongdo is up to about 15 m depth. And the boundary line of between extended bedrocks and seabottom is unclear in the southern nearshore of the Dongdo. On the other hand, the southern coast of the Seodo is characterized by relatively large scale underwater rocks and evenly distributed sediments, which clearly distinguish the boundary of between extended bedrocks and seafloor. This is because the tuff layers exposed to the coastal cliffs of the Dongdo are weak against weathering and erosion. It is considered that there are more influences of the clastic sediments carried from the land of the Dongdo compared with the Seodo. Particularly, the land of the Dongdo has been undergoing construction activities. And also a highly unstable ground such as faults, joints and cracks appears in the Dongdo. In previous study, there are dissimilar features of the massive tuff breccia formations of the Dongdo and the Seodo. These conditions are thought to have influenced the different seabed characteristics in the southern nearshore areas of the Dongdo and the Seodo.

• Korean Journal of Environment and Ecology
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• v.35 no.2
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• pp.135-153
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• 2021

The demilitarized zone (DMZ) is a border barrier with 248 kilometers in length and about 4 kilometers in width crossing east to west to divide the Korean Peninsula about in half. The boundary at 2 kilometers to the south is called the southern limit line. The DMZ has formed a unique ecosystem through a natural ecological succession after the Armistice Agreement and has high conservation value. However, the use of facilities for the military operation and the unchecked weeding often damage the areas in the vicinities of the southern limit line's iron-railing. This study aimed to prepare basic data for the restoration of damaged barren vegetation. As a result of classifying vegetation communities based on indicator species, 10 communities were identified as follows: Duchesnea indica Community, Hosta longipes Community, Sedum kamtschaticum-Sedum sarmentosum Community, Potentilla anemonefolia Community, Potentilla fragarioides var. major Community, Prunella vulgaris var. lilacina Community, Dendranthema zawadskii var. latilobum-Carex lanceolata Community, Dendranthema zawadskii Community, Plantago asiatica-Trifolium repens Community, and Ixeris stolonifera-Kummerowia striata Community. Highly adaptable species can characterize vegetation in barren areas to environment disturbances because artificial disturbances such as soil erosion, soil compaction, topography change, and forest fires caused by military activities frequently occur in the barren areas within the southern limit line. Most of the dominant species in the communities are composed of plants that are commonly found in the roads, roadsides, bare soil, damaged areas, and grasslands throughout South Korea. Currently, the vegetation in barren areas in the vicinities of the DMZ is in the early ecological succession form that develops from bare soil to herbaceous vegetation. Since dominant species distributed in barren land can grow naturally without special maintenance and management, the data can be useful for future restoration material development or species selection.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.4
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• pp.320-334
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• 2000

Deep-sea surface sediment were analyzed for their geotechnical properties, and the sediment samples were collected with a multiple-corer from 31 stations along the track line (131$^{\circ}$30'W, 5-12$^{\circ}$N) in the northeast equatorial Paciflc. Most of the sediments from the northern part (8-12$^{\circ}$N) showed typical properties of siliceous sediments, whereas the southern part (5-6$^{\circ}$N) showed calcareous characteristics due to high biogenic carbonate productivity in the surface waters, where its water depth was shallower than the carbonate compensation depth (CCD: 4,400 m). Geotechnical properties changed sharply at the boundary of 7$^{\circ}$N. Calcareous sediments from the southern part had low water contents, low porosity, low shear strength, high bulk density and high specific grain density, whereas siliceous sediments from the northern part attained high water content, high porosity, high shear strength, low bulk density and low specific grain density. Higher sediment activities were observed in the northern sediment samples than the southern sediment samples. The core samples of the northern sediments were divided into a semi-liquid upper layer and a consolidated lower layer with a boundary at 5-8 cm. These sediment samples showed a rapid increasing pattern along the downcore in original shear strength when an opposite trend was observed in the southern samples. The results showed that sediment variabilities in geotechnical properties between the northern and southern parts such as productivities of surface water, grain solubility due to water depth variation, sedimentation rate, erosion and redistribution of sediment, and combined sedimentary processes were distinctly different along the latitude.

• Journal of Environmental Science International
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• v.20 no.2
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• pp.275-289
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• 2011

In order to clarify the relation between sea breeze penetration and Planetary Boundary Layer development in southeastern part of the Korean Peninsula, several numerical assessments were carried out using atmospheric numerical model WRF(Weather Research and Forecasting). Compared with onset time of sea breeze at eastern coast area(Uljin), the time at southern coast region(Masan) with complex costal line tend to delay for several hours. The penetration patterns of sea breeze between two coastal regions are some different due to the shape of their coastal line and back ground topography. Intensified valley wind due to high topography of lee side of Uljin can help penetration of sea breeze at early time. So penetration of sea breeze at early time often prevent PBL to develop at Uljin and lower PBL height last for a day time. But because of late penetration of sea breeze at Masna, PBL Height dramatically decrease after 1500LST. The distribution of front genesis function based on the heat and momentum variation are explained obviously the sea breeze penetration patterns and agreed well with the PBL height distribution.

• Geophysics and Geophysical Exploration
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• v.19 no.2
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• pp.97-104
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• 2016

Small to large earthquakes have been reported in Gyeongju and its vicinity in southeast Korea during historical period as well as instrumental observation period. We identified and located more than 300 earthquakes that occurred between January 2010 and December 2014 in a $20km{\times}30km$ area, but were unreported because of their small magnitudes. We used the Joint Hypocenter Determination (JHD) method to minimize the influence of the differences between the actual earth structure and 1-D velocity model for earthquake locations. The potential relationship between the previously reported Quaternary faults and the earthquake hypocenters was investigated. Many micro-earthquakes were found to be located in the southern segment of the Yeonil Tectonic Line, the Seokup fault, and the Waup basin boundary faults.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.434-449
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• 2019

In this study, we develop a new cross-shore sediment module which takes the effect of infra-gravity waves of bound mode, and boundary layer streaming on the sediment transport into account besides the well-known asymmetry and under-tow. In doing so, the effect of individual random waves occurring during the unit observation period of 1 hr on sediment transport is also fully taken into account. To demonstrate how the individual random waves would affect the sediment transport, we numerically simulate the non-linear shoaling process of random wavers over the beach of uniform slope. Numerical results show that with the consistent frequency Boussinesq Eq. the application of which is lately extended to surf zone, we could simulate the saw-tooth profile observed without exception over the surf zone, infra-gravity waves of bound mode, and boundary-layer streaming accurately enough. It is also shown that when yearly highest random waves are modeled by the equivalent nonlinear uniform waves, the maximum cross-shore transport rate well exceeds the one where the randomness is fully taken into account as much as three times. Besides, in order to optimize the free parameter K involved in the long-shore sediment module, we carry out the numerical simulation to trace the yearly shoreline change of Mang-Bang beach from 2017.4.26 to 2018.4.20 as well, and proceeds to optimize the K by comparing the traced shoreline change with the measured one. Numerical results show that the optimized K for Mang-Bang beach would be 0.17. With K = 0.17, via yearly grand circulation process comprising severe erosion by consecutively occurring yearly highest waves at the end of October, and gradual recovery over the winter and spring by swell, the advance of shore-line at the northern and southern ends of Mang-Bang beach by 18 m, and the retreat of shore-line by 2.4 m at the middle of Mang-Bang beach can be successfully duplicated in the numerical simulation.

• Korean Journal of Heritage: History & Science
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• v.52 no.1
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• pp.258-271
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• 2019

Recent changes in inter-Korean relations have encouraged South Korean archaeologists' interest in northern cultural heritage and their desire to conduct research. However, it is doubtful how much the South Korea really knows about the cultural ruins in North Korea and the cultural ruins to be found in the DMZ. In Korea, research data on the Japanese colonial period is scattered amongst national institutions and it is not possible to to collect, identify and document the data available in each institution. Typically, the data of Keiichi Ogawa(小川敬吉) is difficult to understand in its printed from. In addition, Ogawa has collected data from several national government agencies, and work is underway to collect architectural data and construct digital archives. This situation will not occur if we publish the data collected so far in digital form. Therefore, there is an urgent need to fully disclose the data related to Cheolwon which is owned by national institutions. If this data is analyzed, sufficient archaeological information can be obtained without excavation. On the other hand, one must wonder if the whole landscape of Cheolwon castle of Taebongguk cand be understood by investigating the interior of Cheolwon castle. This effort should be preceded by a survey on the ruins and the remains of the southern part of the southern boundary line. Rapid development and large-scale arrangement of cultivated land are likely to make it difficult to restore the external landscape related to the tillage demand that is required by the current situation. In the process of restoration of the actual Gyeongwon Line, it has been confirmed that serious irregularity has caused damage and the landscape has been transformed. In order to minimize these risks, it is urgent that we investigate the relics scattered in the southern part of the country, and not devote ourselves to the investigation of Cheolwon. In this regard, how much military, roads, excavation and archaeologists are prepared, centered on Cheolwon and scenery is an important question. I am curious as to how much preparation is provided to the Chulwon-gun and Gangwon-do in terms of administrative assistance, and how much archaeologists and excavation agencies are aware of the archaeological information of the inside and the southern part of the DMZ. Furthermore, how long have people been aware of the archaeological remains on the North Korean side? In order for da iscussion on Cheolwon and scenery to progress, it is necessary to carry out a precise investigation and accumulation of data on the remains in South Korea.

• Ocean and Polar Research
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• v.36 no.3
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• pp.255-276
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• 2014

The dispute between China and Japan regarding $Di\grave{a}oy\acute{u}t\acute{a}i$ is believed to be quite similar to the controversy surrounding Dokdo in terms of historical and post-war processes except for the point that the phenomena of occupation is different with regard to Dokdo. China's claim to $Di\grave{a}oy\acute{u}t\acute{a}i$ is based on historical title and continuous use while the basis of Japan's claim is summarized as preoccupancy of ownerless land. Even though Japan acknowledges that China discovered $Di\grave{a}oy\acute{u}t\acute{a}i$, Japan claims that the act to establish sovereignty over the island from the standpoint of International Law was not taken by China. However, at that time, effective occupation was not an essential prerequisite for the acquisition of a territory. That is to say, from a legal perspective, the legal right for an area could be established based on the discovery of the land, and so it is thought that Japan is applying the current criteria of International Law in a manner that is inappropriate. When we review the post-war process, the San Francisco Peace Treaty does not directly mention $Di\grave{a}oy\acute{u}t\acute{a}i$. But based on the said treaty, we can note that Japan gave up all rights for the southern area that is north of the boundary line that equates to latitude $29^{\circ}$ and that includes the Ryuku Islands and $Di\grave{a}oy\acute{u}t\acute{a}i$. Of course, the provisions for the territory in the San Francisco Peace Treaty and its disposal are not the final factor for the judgment regarding dominium of $Di\grave{a}oy\acute{u}t\acute{a}i$. However, it seems clear that Japan's attitude and interpretation regarding the issues of $Di\grave{a}oy\acute{u}t\acute{a}i$, the Kuril Islands and Dokdo is problematic.

• Economic and Environmental Geology
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• v.15 no.2
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• pp.65-88
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• 1982

In the last ten years, marine geological and geophysical survey and research were conducted by Japanese, Russian and American scientists in the East Sea of Korea (Japan Sea). Many research results were published. However, regional research of the geology of the continental margin of the Korean Peninsula was not conducted. This study has made on attempt to classify submarine strata and stratigraphic boundaries. The study has revealed characters of submarine geology and structure. Isopach maps of each identified stratigraphic unit have been constructed as the results of this study. The study was conducted on the basis of analyses of marine seismic surveys carried out in the continental margin of the East Sea between Kangneung and Pohang. Three depositional basins were identified in the study area and they were named as, Mukho Basin, Hupo Basin and Pohang Basin. The Mukho Basin is developed in continental slope and shelf in the area between Kangneung and Samcheog. Quaternary and Pliocene sediments attain a maximum thickness of 900 m. Basement rocks are interpreted as granite and gneiss. They are correlated with granite-gneiss of the Taebaecksan Series of Pre-cambrian age and the Daebo granite of Jurassic age. The Hupo Basin is developed in the continental shelf between Uljin and Youngdeok. Quaternary and Pliocene sediments attain a maximum thickness of 600 m. Basement rocks were interpreted as granite and gneiss and they are correlated with metamorphic rocks of Pre-cambrian age and the Daebo granites, comprising the Ryongnam Massif. The Pohang Basin is developed in the area between Pohang and Gangu. This basin contains Miocene and older sediments. Basement rocks are not shown. Many faults are developed within the continental shelf and slope. These faults strike parallel with the coast line. A north-south direction is predominant in the southern study area. However, in the northern study area the faults strike north, and north-west. The faults are parallel to each other and are step faults down-thrown to the east or west, forming horst and graben structures which develop into sedimentary basins. Such faults caused the development of submarine banks along the boundary between the continental shelf and slope. This bank has acted as a barrier for deposition in the Hupo Basin. Paleozoic sedimentary rocks distributed widely in the adjacent land area are absent in the Mukho Basin. This suggests that the area of the basin was situated above the sea level until the Pliocene time. The study area contains Pliocene sediments in general. These sediments overlie the basement complex composed of metamorphic rocks, granites, Cretaceous (Kyongsang System) sedimentary rocks and Miocene sedimentary rocks. These facts lead to a conclusion that the continental shelf and slope of the study area were developed as a result of displacements along faults oriented parallel to the present coast line in the post Miocene time.

• Korean Journal of Plant Resources
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• v.29 no.1
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• pp.110-127
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• 2016

This floristic study was conducted from April to September, 2014 in 12 days. The investigated area was Mt. Segeolsan (1,261 m) which is the part of Chirisan National Park and its neighbor region, Goan-ri, Sandeuk-ri. Based on voucher specimens, flora of this area consisted of 108 families, 376 genera, 584 species, 5 subspecies, 73 varieties, and 16 forma, totally 679 taxa. 17 taxa were endemic to Korea such as Carex okamotoi Ohwi, Cimicifuga austrokoreana H.W. Lee & C.W. Park., Thalictrum rochebrunianum var. grandisepalum (H.Lév.) Nakai, Fallopia koreana B.U. Oh & J.G. Kim, Asarum patens (Yamaki) Yamaki ex Y.N. Lee, and Stewartia pseudocamellia Maxim. etc. Among these species, C. austrokoreana, T. rochebrunianum var. grandisepalum, F. koreana, A. patens are considered having a southern boundary line of distribution in the Chirisan National Park region. And so Carex okamotoi has main distribution center in the Chirisan National Park region, this study region is assumed important in phytogeography. The useful plants were 633 taxa, ethonobotanic plants were 359 taxa in this area. Invasive alien species were 61 taxa, which were naturalized rate (9.0%) and urbanized index (17.4%).