• The Journal of Engineering Geology
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• v.25 no.2
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• pp.201-213
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• 2015

Site effects resulting in the amplification of earthquake ground motion are strongly influenced not only by the subsurface soil conditions and structure, but also by the surface topography. Yet, over the last several decades, most studies of site-specific seismic responses in Korea have focused primarily on the seismic amplification associated with geologic and soil conditions. For example, the effects of local geology are now well established and have been incorporated into current Korean seismic design codes, whereas topographic effects have not been considered. To help address this shortcoming, two-dimensional (2D) seismic site response analyses, using finite element (FE) ground modeling with three different slope angles, were performed in order to assess the site effects of surface topography. We then compared our results, specifically peak ground acceleration (PGA) and acceleration response spectrum, to those of one-dimensional (1D) FE model analyses conducted alongside our study. Throughout much of the upper slope region, PGAs and spectral accelerations are larger in the 2D analyses than in the 1D analyses as a result of the topographic effect.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.202-202
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• 2011

상습침수지역 산사태위험지역 등 지형적인 여건 등으로 인해 재해가 발생할 우려가 있는 지역을 관리하기 위하여 "자연재해대책법"에 의해 지정되는 지구를 자연재해위험지구라 하며 특히 집중호우에 의한 도심지 주변 상습침수지역에 대한 체계적인 연구와 해석방법이 요구되는 실정이다. 이에 본 연구에서는 강원도 삼척시의 상습침수지역인 오십천 주변 자원동일대를 대상으로 수문학적 인자인 강우자료와 지형자료를 조사하고 도시유역 유출해석모형인 XP-SWMM을 적용하여 유출부에서의 본류수심을 고려한 재해위험지역의 하천범람과 내수침수 범위를 산정하였다. 연구지역은 GIS 프로그램인 ArcView를 이용하여 총 16개의 소유역으로 구분하고 총 노드 75개 총 링크 74개를 생성하고 분석하였다. 그 결과 2002년, 2003년의 태풍발생에 의해 침수된 지역의 특성을 하류지역의 경우 잘 반영하였으며 상류지역의 경우는 얕은 침수심을 갖으며 좀 더 넓게 침수피해가 발생하는 것으로 분석되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.112-112
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• 2015

우리나라는 산지가 국토의 64%이상으로 토석류 등 지반재해의 위험성에 노출되어 있다. 2011년 7월 우면산 토석류, 춘천시 펜션 토석류 등 규모가 큰 토석류 재해가 일어나며 문제가 되고 있다. 이에 본 연구에서는 토석류 피해지역을 연구지역으로 선정하고 지상 LiDAR스캔을 통한 현장조사로 연구지역과 유사한 매개변수 값을 산정하고 정밀도가 높은 지형자료를 생성하여 토석류 해석에 대한 정확도를 높혔다. 토석류 해석프로그램은 국내에서 토석류 해석에 많이 사용되는 FLO-2D와 아직 국내에서는 사용 빈도가 높지는 않지만 국외 연구사례에서 사용 빈도가 높은 모델 중 RAMMS 모형을 선정하여 토석류 피해가 발생한 동일 지역에 두 모형을 적용하고 그 적용성을 검토하였다.

• Journal of the Korean Geographical Society
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• v.31 no.2
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• pp.106-127
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• 1996

In Korea, modern geomorphology has developed as one of main subjects in geography, such as in Europe. Geomorphology is one of the most advanced specialties in the geography dicipline, since foundation of Korean Geographical Society in 1945. Untill 1960's study, first generation of the Korean geomorphologists trained the younger ones, together with energetic research activities. Their great works in education and research established the base of ulterier development of the geomorphology in Korea. Since 1970s, research manpower and quality has incresed rapidly, partly due to the various international activities and cooperations of Korean geomorphologists. Owing to above development, Korean geomorphologist was able to found "The Geomorphological Association of Korea" in 1990 and publish "Journal of GAK", since 1994. Furthermore, geomorphologists are playing important roles in interdisciplinary academic societies, such as "The Korean Quaternary Assocition". Still 1960s, our research had focused on the identification and interpretation of erosional surfaces in Korea Peninsular. Of course, W.M. Davis's "Geographical Cycle Theory" and L.C. King's "Pedimentation Theory" had a great influence on the Koerans' works. After 1970s, the study of erosional surface played the important role in setting up the morphoclimatic viewpoint and methodology. Research scope tend to be notably broad and various than it was untill 1960's. Disposotion of the scientific methods and techniques become more and more apparent. These trends of research has settled precise descreption and interpretation of actual landforms, based on the careful field works, scientific measuring, and analisis, rather than methodology focused on the particular master theories. Recent geomorphological researches show the scope from climatic geomorphology and Quaternary geomorphology to granite and limestone weathering, pedo-geomorphogenic environment and periglacial landforms, focused on the small-to-medium scales. And then there have been new trying to interprete erosional surfaces such as hillslopes and terraces. Also, studies of coastal and plain landforms have been successfully developed. Recent new trends show the quantitative and analytic modelling using field measurement and laboratory work, and study on the human impacts on the natural landforms.y on the human impacts on the natural landforms.

• Journal of Korea Water Resources Association
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• v.51 no.6
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• pp.481-490
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• 2018

Recently, the spatiotemporal patterns of flood disasters have become more complex and unpredictable due to climate change. Flood hazard map including information on flood risk level has been widely used as an unstructured measure against flooding damages. In order to product a high-precision flood hazard map by combination of hydrologic and hydraulic modeling, huge digital information such as topography, geology, climate, landuse and various database related to social economic are required. However, in some areas, especially in developing countries, flood hazard mapping is difficult or impossible and its accuracy is insufficient because such data is lacking or inaccessible. Therefore, this study suggests a method to delineate large scale flood-prone area based on topographic factors produced by linear binary classifier and ROC (Receiver Operation Characteristics) using globally-available geographic data such as ASTER or SRTM. We applied the proposed methodology to five different countries: North Korea Bangladesh, Indonesia, Thailand and Myanmar. The results show that model performances on flood area detection ranges from 38% (Bangladesh) to 78% (Thailand). The flood-prone area detection based on the topographical factors has a great advantage in order to easily distinguish the large-scale inundation-potent area using only digital elevation model (DEM) for ungauged watersheds.

• Journal of Wetlands Research
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• v.18 no.1
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• pp.45-57
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• 2016

Levee safety is being evaluated using one of the several failure causes including overtopping, infiltration and erosion or 1D hydraulic analysis considering physical characteristics of levee in practical engineering works. However, mentioned evaluation methods are not able to consider various failure causes of levee at the same time and to get reliable results where requires the accurate topographic information. This study proposed the flood hazard index which is able to consider several hazard factors involving overtopping, infiltration and erosion risk simultaneously. The index was generated from results of 2D hydraulic analysis reflecting accurate topographic information. The study areas are the confluences of the Nakdong River and two streams(Gamcheon and Hoecheon). Levee safety was evaluated using results based on 2D hydraulic analysis considering riverbed changes of before and after dredging work in the study area. This study will contribute to estimate the reliable safety evaluation of levee where may have hazards during extreme flood events.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.2
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• pp.91-99
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• 2009

In the field of geospatial information, 3D shape information has been considered as a frame data for GIS. Many kind of physical shape information is, especially, required for the works related with space, such as planning, maintenance, management, etc. Conventional photogrammetry was implemented under the conditions with expensive metric cameras and analytical plotters operated by experts. Nowadays, however, the metric cameras and analytical plotters are replaced by low price non-metric digital cameras and personal computers by virtue of the progress in digital photogrammetry. This study aims to investigate the technology to easily and promptly produce 3D shape information required in geospatial information system using close-range photogrammetry with non-metric digital cameras. As the results of this study, 3D shape of an experimental object was made out with a common compact digital camera and only a known length of a line component in the object and the accuracy of the dimension of 3D shape was analyzed to be less than one pixel.

• Geophysics and Geophysical Exploration
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• v.13 no.2
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• pp.169-174
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• 2010

We developed a precise terrain correction program using triangular element method (TEM) for microgravity data processing. TEM calculates gravity attraction of arbitrary polyhedra whose surface is patched by triangles. We showed that TEM can calculate more precise terrain effect than conventional rectangular prism method. We tested the accuracy of TEM on the cone model which has analytic solution. Also, we tested the accuracy of TEM on the slope model, this results showed that there are big differences calculated by TEM and rectangular prsim method (RPM) on slope model. The developed terrain correction program was applied on the gravity data on the southern area near sea shore of Korean peninsula, calculated terrain effect very precisely.

• Journal of the Korean Association of Geographic Information Studies
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• v.4 no.3
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• pp.21-30
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• 2001

This research was carried out for analyzing watershed and river topography. The method based on experience and map was mainly used, but derived data are too much to effectively analyze. Therefore some researchers have introduced computer system using GIS technique and remote sensing data. This research used GIS and remote sensing technique for classifying and analyzing watershed and river topography. Also dendrochronology method was introduced for guessing the creation times of deposits. Stream order map, sub-basin delineation map, river-bed microtopograpy were produced through this research. These results may be used in planning for Donggang conservation.

• Tunnel and Underground Space
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• v.14 no.2
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• pp.142-153
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• 2004

To investigate the influence of the rock mass inhomogeneity caused by layer geometry on the regional stress distribution the cuboid models considering a homogenous rock mass, inhomogeneous rock mass with plane layers and with uneven layers were analyzed and discussed. It was confirmed that the structure and existence of layers in rock mass affected the regional stress distribution. An approach based on an inverse analysis of the measured local stresses and the 3D finite element analysis was suggested, and used to estimate the regional stress field of the homogeneous and inhomogeneous models, which consist of the surface geometry of ground and both the surface and layer geometry respectively. Additionally, the approach of the regional stress considering the layer geometry in the rock mass was verified to estimate the regional stress field for a site.