• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2003.03a
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• pp.13-30
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• 2003

In this paper, a new systematic method will be introduced, in which a Rock-mass Prediction System(RPS) predicts the geological conditions and rock mass movements before tunnel excavation and the appropriate counter-measures are taken in the expected weak zones during tunnel construction. The Rock-mass Prediction System(RPS) consists of the LIM, a horizontal core drilling and a seismic exploration method(TSP/HSP). In the Rock-mass Prediction System(RPS), the seismic exploration method (TSP/HSP) gives information on the locations of the weak zones such as major faults and voids in wide-range, and the horizontal core drillings are utilized to find exact location and widths of the faults or voids near the weak zones which was predicted by the seismic exploration method (TSP/HSP). The LIM is used to find the hardness of the rock mass and small weak zones near the excavation face. The Rock-mass Prediction System (RPS) was successfully applied to the Sol-An Tunnel and the effectiveness of the system was verified.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.3
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• pp.31-43
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• 2001

In this study, we carried out investigation and analysis on damages in tunnels on order to provide the basic information for the safety assessment of tunnels and to minimize the potential damage of the same kind as investigated. The frequencies of occurrence in terms of 4 items, i.e., service life interval, type of the damage, cause of the damage, and geological condition, were examined and summarized based on 44 foreign and domestic cases of tunnel damages. Also, we carried out a survey research of which the content included 28 questions on the tunnel safety assessment. The answers collected from domestic experts in tunneling suggested that the most probable cause of the tunnel damages was cracking in tunnels at 42~58%. They also suggested that the poor constrution work strongly caused the damages. Therefore, to ensure tunnel safety, high quality of constrution should be maintained as examined. The types of damage and their extent of influence on the overall tunnel safety are of practical importance to be used in the artficial intelligent system for tunnel safety assessment.

• Geosciences Journal
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• v.22 no.6
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• pp.871-880
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• 2018

During and shortly after the 2017 Pohang Earthquake ($M_w$ 5.4), sand blows were observed around the epicenter for the first time since the beginning of instrumental seismic recording in South Korea. We carried out field surveys plus satellite and drone imagery analyses, resulting in observation of approximately 600 sand blows on Quaternary sediment cover in this area. Most were observed within 3 km of the epicenter, with the farthest being 15 km away. In order to investigate the ground's susceptibility to liquefaction, we conducted a trench study of a 30 m-long sand blow in a rice field 1 km from the earthquake epicenter. The physical characteristics of the liquified sediments (grain size, impermeable barriers, saturation, and low overburden pressure) closely matched the optimum ground conditions for liquefaction. Additionally, we found a series of soft sediment deformation structures (SSDSs) within the trench walls, such as load structures and water-escaped structures. The latter were vertically connected to sand blows on the surface, reflecting seismogenic liquefaction involving subsurface deformation during sand blow formation. This genetic linkage suggests that SSDS research would be useful for identifying prehistoric damage-inducing earthquakes ($M_w$ > 5.0) in South Korea because SSDSs have a lower formation threshold and higher preservational potential than geomorphic markers formed by surface ruptures. Thus, future combined studies of Quaternary surface faults and SSDSs are required to provide reliable paleoseismological information in Korea.

• Korean Journal of Remote Sensing
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• v.19 no.4
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• pp.291-305
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• 2003

The cost of deploying Geological and Environmental information gathering systems, especially when such systems obtain remote sensing and photographic data through the use of commercial satellites and aircraft. Besides the high cost equipment required, adverse weather conditions can further restrict a researcher's ability to collect data anywhere and anytime. To mitigate this problem, we have developed a compact, multi-spectral automatic Aerial photographic system. This system's Multi-spectral camera is capable of the visible (RGB) and infrared (NIR) bands (3032*2008 pixel). It consists of a thermal infrared camera and automatic balance control, and can be managed by a palm-top computer. Other features includes a camera gimbal system, GPS receiver, weather sensor among others. We have evaluated the efficiency of this system in several field tests at the following locations: Kyongsang-bukdo beach, Nakdong river (at each site of mulkeum-namji and koryung-gumi), and Kyungahn River. Its tested ability in aerial photography, weather data, as well as GPS data acquisition demonstrates its flexibility as a tool for environmental data monitoring.

• Korean Journal of Remote Sensing
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• v.21 no.6
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• pp.493-503
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• 2005

In this study, the weight of evidence(WofE) technique based on GIS was applied to spatially estimate the groundwater yield characteristics at the Pocheon area In Gyunggi-do. The groundwater preservation depends on many hydro-geologic factors that include hydrologic data, land-use data, topographic data, geological map and other natural materials collected at the site, even with man-made things. All these data can be digitally processed and managed by GIS database. In the applied technique of WofE, the prior probabilities were estimated as the factors that affect the yield on lineament, geology, drainage pattern or river system density, landuse and soil. We calculated the value of the weight values, W+ and W-, of each factor and estimated the contrast value of it. Results by the groundwater yield characteristic computation using this scheme were presented feasibility map in the form of the posterior probability to the consideration of in-situ samples. It is concluded that this technique is regarded as one of the effective techniques for the feasibility mapping related to the estimation of groundwater-bearing potential zones and its spatial pattern.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.269-281
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• 2021

Land creeping is the imperceptibly slow, steady, downward movement o f slope-forming soil or rock. Because creep-related failures occur frequently on a large scale without notice, they can be hazardous to both property and human life. Korea Forest Service has operated the prevention and response system from land creeping which has been on the rise since 2018. We categorized and proposed three survey steps (e.g., preliminary, regional, detailed) for investigation of creeping susceptibility site with a focus on geophysical mapping of a selected test site, Yongheung-dong, Pohang, Korea. The combination of geophysical (dipole-dipole electrical resistivity tomography and reciprocal seismic refraction technique, well-logging), geotechnical studies (standard penetrating test, laboratory tests), field mapping (tension cracks, uplift, fault), and comprehensive interpretation of their results provided the reliable information of the subsurface structures including the failure surface. To further investigate the subsurface structure including the sliding zone, we performed high-resolution geophysical mapping in addition to the regional survey. High-resolution seismic velocity structures are employed for stability analysis because they provided more simplified layers of weathering rock, soft rock, and hard rock. Curved slip plane of the land creeping is effectively delineated with a shape of downslope sliding and upward pushing at the apex of high resistive bedrock in high-resolution electrical resistivity model with clay-mineral contents taken into account. Proposed survey steps and comprehensive interpretation schemes of the results from geological, geophysical, and geotechnical data should be effective for data sets collected in a similar environment to land-creeping susceptibility area.

• Journal of recreation and landscape
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• v.12 no.4
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• pp.59-66
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• 2018

The purpose of the present study was to compare the long-term management objectives, policy objectives, implementation plans, and detailed plans of four provincial parks established in 2013 using various analysis frameworks. Through this, the study aimed to identify the characteristics of the management plan and extract the implementation plan important to each park by analyzing the priorities in the detailed plan. The long-term management objectives of most parks were to maintain recreational functions by utilizing all the resources of the park, rather than merely preserving the ecosystem. From an ecological perspective, information on major plants and legal protection species are included for most parks, and geological and topographic features considered a major resource. For sustainable forests, it is important to induce the dispersion of concentrated use space. Efficient management systems are distinctively differentiated among the parks. For regional revitalization, the management of programs to link provincial parks and their surrounding areas has become most important. From an ecological perspective, priorities differed for the parks according to their ecological characteristics. For sustainable forests, Moaksan Provincial Park prioritized the visitor reservation system related to the overall park, while the other three parks prioritized alleviating the concentrated use of specific areas. From an efficient management perspective, Daedunsan Provincial Park prioritized aspects related to the cableway. Maisan Provincial Park prioritized inducing the linkage between the use of natural and cultural resources, and Seonunsan Provincial Park prioritized establishing an ecological and cultural commentary operating system. For the base-type leisure activity space, Moaksan Provincial Park prioritized the systematic management and operation of the pilgrimage route, Maisan Provincial Park the connection between the Maisan geography and residents' income, and Seonunsan Provincial Park providing a space for ecological education.

• Korean Journal of Remote Sensing
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• v.35 no.1
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• pp.179-193
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• 2019

Landslides are one of the most damaging geological hazards worldwide, threating both humans and property. Hence, there have been many efforts to prevent landslides and mitigate the damage that they cause. Among such efforts, there have been many studies on mapping landslide susceptibility. Geographic information system (GIS)-based techniques have been developed and applied widely, and are now the main tools used to map landslide susceptibility. We reviewed the status of landslide susceptibility mapping using GIS by number of papers, year, study area, number of landslides, cause, and models applied, based on 776 articles over the last 20 years (1999-2018). The number of studies published annually increased rapidly over time. The total study area spanned 65 countries, and 47.7% of study areas were in China, India, South Korea, and Iran, where more than 500 landslides, 27.3% of all landslides, have occurred. Slope (97.6% of total articles) and geology (82.7% of total articles) were most often implicated as causes, and logistic regression (26.9% of total articles) and frequency ratio (24.7% of total article) models were the most widely used models. We analyzed trends in the causes of and models used to simulate landslides. The main causes were similar each year, but machine learning models have increased in popularity over time. In the future, more study areas should be investigated to improve the generalizability and accuracy of the results. Furthermore, more causes, especially those related to topography and soil, should be considered and more machine learning models should be applied. Finally, landslide hazard and risk maps should be studied in addition to landslide susceptibility maps.

• Geophysics and Geophysical Exploration
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• v.22 no.2
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• pp.80-87
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• 2019

In this paper, we propose a method to apply the polynomial fitting for regional-residual separation of microgravity data based on the characteristics of gravity anomaly without a prior information. Since the microgravity survey is usually carried out in small regions, it is common to approximate regional anomaly by the first-order polynomial plane. However, if the regional anomaly patterns are difficult to be approximated to a first-order plane, the complete gravity anomaly is divided into small zones enough to approximate first-order plane by means of Parasnis density estimation method. The regional-residual separation is then applied on the splitted zones individually. When the gravity anomalies can be splitted spatially, we showed that the residual anomalies can be more effectively extracted based on the regional geological structures by regional anomaly separation from each of the divided regions, rather than applying the entire data set at one time.

• Geophysics and Geophysical Exploration
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• v.22 no.1
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• pp.29-36
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• 2019

Regional airborne magnetic survey is very cost-effective mapping tool. Magnetic anomaly maps have abundant information, which are an important tool for understanding the geological evolution and mineral exploration. For this reason, the governments of many countries have made significant investment in the acquisition of airborne geophysical data over many decades. KIGAM (Korea Institute of Geoscience and Mineral Resources) began nationwide airborne magnetic mapping programme in 1982, and completed in 2017. The obtained magnetic data was reprocessed and magnetic database was built in 2018. In addition, the magnetic anomaly map of Korea with a scale of 1:1,000,000 was published. In this paper, we introduced a new magnetic anomaly map of Korea through describing the changing survey parameters during data acquisitions and history of data processing.