• Journal of the Korean Geographical Society
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• v.38 no.3
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• pp.389-399
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• 2003

CRN (Cosmogenic radionuclide) methodology has been a versatile tool applicable to a wide range of geomorphology. This study was underiaken to ascertain the rate of erosion and exposure age of mountain-top detritus (tors and block streams) on Mt. Maneo by employing the concentrations of in-situ produced cosmogenic $^{10}$ Be and $^{26}$ Al from bedrock surfaces that are exposed to cosmic rays. The results suggest that tors on the summit were positioned here during the glacial period but no later than 65ka and block streams have been stabilized also since the last glacial period but no later than 38ka. The tors on the summit have been eroded at a slower rate (9m/Ma) than blocks on the hillslope (15m/Ma) since the initial abrupt exposure of each landform to cosmic rays, suggesting that there is a slight difference in the rate of erosion between the summit and the hillslope, and that the local relief between the two areas has been increased. When the $^{26}$ Al/$^{10}$ Be-$^{10}$ Be concentrations from samples are plotted in Lal's steady-state erosion island, one sample (from a for) has complex exposure histories, which can be explained by the occurrence of multiple chipping event of 5cm to 60cm in length on the surface of the rock.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.35-57
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• 2011

Minor erosional forms in the bedrock river, like potholes, are not just research subject for the professional geomorphologis. In addition, these features attract general public and make them understand the social contribution and importance of geomorphologic research activities. In this paper, the studies on bedrock minor forms in Korea was reviewed. For further researches, some of major erosional processes and minor forms in bedrock rivers were discussed in detail. Cavitation, plucking, hydro-wedging, and abrasion by passing sediment particles are the major processes to create the longitudinal or transverse minor forms like pothole, furrows, flutes, and runnels. Especially the definition of furrows and runnels are explained to prevent the confusion with pothole, weathering pits and grooves. To make a progress in research on bedrock minor forms the quantitative relationship between the variables should be studied. New techniques for scientific estimation of erosion rates and exposure ages of bedrock surfaces should be used in this field.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.153-163
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• 2020

Mineral and geochemical analysis were conducted on two sections (~3.5 m) of red-brown claysilt sediments covering the gneiss and granite weathering zones in Suwon-si for establishing Quaternary paleoenvironmental changes in Korea. The sections were divided into four sedimentary layers (Unit 1-4) by vertical changes in mineral composition and chemical composition. The lowermost unit 1 was a sandy sediment with a high K-feldspar content with a significant contribution of weathered bedrock. Unit 2 was a transition layer showing intermediate characteristics. Unit 3 was a reddish brown clay-silt sediment, with a total clay content of 58% on average, and the main clay minerals were illite-smectite mixed layer minerals and hydroxy-interlayered vermiculite/smectite. Unit 3 contained almost no plagioclase, while the content of kaolin minerals derived by the plagioclase weathering was higher than in the other layers. Unit 4 had similar mineral composition and chemical properties to Unit 3, but had a higher content of plagioclase and chlorite and lower content of kaolin minerals. The chemical compositions of the sections were compared with those in other regions of Korea, suggesting the eolian origin of Units 3 and 4. The paleoenvironmental change in the sedimentary section of this region was interpreted as follows. Weathered products of gneiss and granite, which are bedrocks of this region, were eroded and deposited as sandy sediments in the periphery to form the lower layers (Unit 1, 2), followed by the deposition of the claysilty rich eolian sediments (Unit 3) during the glacial. Unit 3 was chemically weathered during the warm humid climate during the last interglacial, developing a reddish brown color. After that, a eolian sediment layer (Unit 4) was deposited during the last glacial.

• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.300-312
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• 2004

The geomorphological environment of Suwon Basin consists of two great elements: mountains which surround the basin and plains and low relief hills by differential erosion of granitic area. Nothern and eastern parts of the basin surround with gneissic mountains(Mt. Kwangkyo), southern and western parts of the basin with granitic mountains(Mt. Chilbo, etc). The basin developed on granitic saprolites is composed of two types of sub-order geomorphic elements: flood plains alongside four river(Whangkuji-chon, Seoho-chon, Suwon-chon, Wonchonri-chon) and aligned hills and mounts between the river side plains. While the low down lands provided the spatial condition for the extention of downtown of Suwon, the gneissic mountains have played the positive roles by high ecological dam effects with stable supply of water and purification of air, etc.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.133-133
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• 2023

풍화작용에 의해 생성된 유사는 자연 매체에 의해 이동하고 하천에 도달하기 이전이나 이후 퇴적되며, 해당 과정 중에서 하상변동, 홍수위 상승, 제방 안정성, 두부 침식, 생태환경 변화, 수질문제 등 다양한 침식과 퇴적 관련 문제들이 발생한다. 이러한 유사 문제의 해결과 지속적인 하천관리를 위해서는 유사의 생성, 이송, 그리고 퇴적 과정에 대한 충분한 이해와 정량적인 유사량을 파악하는 것이 필수적이다. 다양한 연구들을 통해서 유사량을 정량적으로 파악하기 위해 여러 종류의 모델과 공식들이 제안 되어져 왔다. 그 중 경험적 모델의 경우 실제로 관측된 값을 기반으로 하며, 복잡한 계산이나 요구하는 자료가 다른 종류의 모델들 보다 적어 쉽게 접근이 가능하다. 이러한 경험적 모델은 유사에 영향을 주는 인자를 규명하거나 특정 유역이나 지역에서 이송 및 퇴적 되는 유사의 출처와 특성을 규명하는 초기 단계에서 유용하게 이용된다. 국내 하천의 경우 여름에 강우가 집중되고 대부분의 국토가 산지로 이루어져있어 상류에서 침식이 주로 발생한다. 또한, 본류 및 하류 지역의 하천은 유사의 퇴적이 주로 일어나서 하천의 형태와 물길이 형성된 충적 하천 형태로 발전 되어있기 때문에 국내 하천에서는 전반적으로 국부적이며 다양한 형태의 유사 관련 문제가 발생한다. 국내 하천에서 발생하는 유사 관련 문제를 해결하기 위해 국내 하천의 유사량을 추정하는 다양한 경험적 모델들이 지속적으로 개발되어왔다. 하지만 과거에 개발된 모델들의 경우 계측 자료가 충분하지 않은 시기에 개발 되었으며, 현재에는 활용하기 불가능하다. 본 연구에서는 국내 하천의 비유사량을 예측하는 동시에 국내 하천의 유사 특성을 이해하기 위해 과거에 국내 하천을 대상으로 비유사량을 추정하기 위해 개발되었던 경험적 모델을 개선하였다. 본 연구를 통해 기존 경험 모델의 경우 주기적인 업데이트가 필요함을 확인하였으며, 개발된 모델의 경우 국내 하천 유사 관리를 위해 미래 유사량 예측하는 등 다양한 방면으로 활용 관리가 가능할 것으로 보인다.

• Journal of the Mineralogical Society of Korea
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• v.18 no.2
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• pp.135-144
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• 2005

In the high-Ca limestone zone of the Pungchon Formation of the Lower Chosun Supergroup, cryptocrystalline alterations with reddish brown color occur as fissure-fillings or coatings, which was originated from the upper formation, i. e., the Hwajeol Formation. The precipitates result in degradation and contamination of the high-Ca limestone ore in grade and quality, showing characteristic occurrence and mineral composition typical of suggesting a supergene origin. Chalcedonic quartz, kaolinite, illite, goethite and hematite are constituting a characteristic authigenic mineral assemblage and, in places, smectite is less commonly included in the weathering product. In addition to these authigenic phases, some detrital minerals such as mica and orthoclase constituting relatively coarser grains are also rarely present in the supergene alterations. A rather complex clay facies consisting of kaolinite, illite and smectite in the alterations seems to correspond to the typical clay composition of the reported residual pedogenic soils by limestone weathering. The cryptocrystalline weathering product is partly altered to stilbite, a characteristic hydrothermal zeolite, in places, by the hydrothermal contact of late stage. The time of formation and infiltration of the supergene alterations seems to correspond to the stage just after the epithermal alteration of the Pungchon Limestone, i. e., an early Jurassic age. The supergene alteration, which may imply the stage of uplifting, weathering and erosion of the Chosun Supergroup, appears to have undergone at an oxygen-rich environment in descending water of meteoric origin by means of a chemical leaching and diffusion.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2004.06a
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• pp.73-76
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• 2004

인류 문화 발달에 있어 언어의 발달과 함께 이루어진 가장 초기 단계의 의사소통 수단은 몸짓이며, 또 다른 정보 교류 방법은 그림이다. 그런 점에서 구석기 시대의 동굴 암각화에서 볼 수 있는 들소, 사슴, 큰 새 등은 단순히 대상물을 묘사한 개별적 그림으로 가정하기 보다는 오히려 종교적 제의 양상을 알려주는 상징으로 이해하는 것이 바람직하다. 그러나 잦은 풍화 작용과 침식 작용으로 인하여 암각화의 인식에는 한계가 있다. 이에 디지털영상처리 기법을 기반으로 인간시각에 더 잘 보이도록 영상을 향상시키면서 더 짧은 연구기간에 더 않은 암각화를 올바로 인식하고, 더 정확하게 문명의 흐름을 밝혀 낼 수 있다. 본 논문에서 디지털 영상처리 기법을 신축적으로 적용시켜 암각화 인식에 거슬리는 불필요한 영상 잡음들을 제거하고 영상을 더 선명하게 보이게 하는 알고리듬을 제안한다.

• Journal of the Korean Geographical Society
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• v.46 no.6
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• pp.673-692
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• 2011

Advances in computer technology have enabled us to develop and use numerical landscape evolution models (NLEMs) for exploring the dynamics of geomorphic system from a variety of viewpoints which previously could have not been taken. However, as of yet there have been no trials using or developing NLEMs in Korea. The purpose of this research is to develop a 2 dimensional NLEM on a geological time scale and evaluate its usefulness. The newly developed NLEM (ND-NLEM) treats bedrock weathering as one of the major geomorphic processes and attempts to simulate the thickness of soil. As such it is possible to model the weathering-limited as well as the transport-limited environment on hillslopes. Moreover the ND-NLEM includes not only slow and continuous mass transport like soil creep, but also rapid and discrete mass transport like landslides. Bedrock incision is simulated in the ND-NLEM where fluvial transport capacity is large enough to move all channel bed loads, such that ND-NLEM can model the detachment-limited environment. Furthermore the ND-NLEM adopts the D-infinity algorithm when routing flows in the model domain, so it reduces distortion due to the use of the steepest descent slope flow direction algorithm. In the experiments to evaluate the usefulness of the ND-NLEM, characteristics of the channel network observed from the model results were similar to those of the case study area for comparison, and the hypsometry curve log during the experiment showed rational evidence of landscape evolution. Therefore, the ND-NLEM is shown to be useful for simulating landscape evolution on a geological time scale.

• Economic and Environmental Geology
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• v.55 no.5
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• pp.541-550
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• 2022

A pre-existing landform is created by weathering and erosion along the bedrock fault and the weak zone. A neotectonic landform is formed by neotectonic movements such as earthquakes, volcanoes, and Quaternary faults. It is difficult to clearly distinguish the landform in the actual field because the influence of the tectonic activity in the Korean Peninsula is relatively small, and the magnitude of surface processes (e.g., erosion and weathering) is intense. Thus, to better understand the impact of tectonic activity and distinguish between pre-existing landforms and neotectonic landforms, it is necessary to understand the development process of pre-existing landforms depending on the bedrock characteristics. This study used a two-dimensional numerical landscape evolution model (LEM) to study the spatio-temporal development of landscape according to the different erodibility under the same factors of climate and the uplift rate. We used hill-slope indices (i.e., relief, mean elevation, and slope) and channels (i.e., longitudinal profile, normalized channel steepness index, and stream order) to distinguish the difference according to different bedrocks. As a result of the analysis, the terrain with high erosion potential shows low mean elevation, gentle slope, low stream order, and channel steepness index. However, the value of the landscape with low erosion potential differs from that with high erodibility. In addition, a knickpoint came out at the boundary of the bedrock. When researching the actual topography, the location around the border of difference in bedrock has only been considered a pre-existing factor. This study suggested that differences in bedrock and various topographic indices should be comprehensively considered to classify pre-existing and active tectonic topography.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.514-527
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• 2004

We investigated the distribution and geomorphic development of alluvial fans at Cheongdo- and Hweyang-eup(town) in the Cheongdo Basin, Gyeongsangbuk-do(Province) of Korea. The alluvial fans of study area are formed confluently to the E-W direction at the northern slope of the Mt. Namsan(840 m). They are classified into Higher surface, Middle surface, and Lower surface according to a relative height to a river bed. And the older alluvial fan is, the deeper gravel in the stream deposits is weathered. The magnitude of each surface composing of confluent fans is related to that of the drainage basin. So called fan-basin system of magnitude on the study area is on the positive(+) relation in the study area. The large fans over 1km in radius are found on the basin of andesite rock which is resistant to the weathering and erosion. Moreover there is no tectonic movement in the basin. It means the most important element influenced on the fan formation is not tectonic movement, but the Quaternary climatic change, which is the periglacial climate alternating glacial and interglacial stages during the Quaternary. Therefore alluvial fans would distribute in Korea overall influenced by the Quaternary climatic change.