• Journal of Korean Society for Geospatial Information Science
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• v.22 no.2
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• pp.3-9
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• 2014

With broadcasting telecommunication, rapid change detection, and construction of spatial information, a long reconnaissance, resources detection in dangerous area and natural disasters, which are difficult for manned aerial vehicles to perform, international recognition in UAV merely being used for limited military purposes has been changed and its demand for both civil and military purpose have been increased. However, considering the current situation that availability of UAV varies and its working areas also broaden, the stability of UAV and the problems of privacy protection are more important in integrated operation of UAV. In particular, the application of UAV system is urgent for the area where rapid decision making due to expedite data construction such as disaster, calamity, and the acquisition of spatial information for small area are required. However, since technical stability for UAV system and institutional regulation in regard of spatial information are not examined, and UAV system has not been integrated with aerial photograph, the limitation of UAV system has been presented. Thus, this study is aimed at analyzing domestic and foreign research trend and institutional research trend in terms of integrated UAV operation, and proposing its implications and the availability of integrated UAV operation for future national spatial information data construction.

• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.57-66
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• 2015

Empirical seismic displacement equations based on the Newmark sliding block method are widely used to develop seismic landslide hazard map. Most proposed equations have been developed for embankments and landfills, and do not consider the dynamic response of sliding block. Therefore, they cannot be applied to Korean mountain slopes composed of thin, uniform soil-layer underlain by an inclined bedrock parallel to the slope. In this paper, a series of two-dimensional dynamic nonlinear finite difference analyses were performed to estimate the permanent seismic slope displacement. The seismic displacement of mountain slopes was calculated using the Newmark method and the equivalent acceleration time history. The calculated seismic displacements of the mountain slopes were compared to a widely used empirical displacement model. We show that the displacement prediction is significantly enhanced if the slope is modeled as a flexible sliding mass and the amplification characteristics are accounted for. Regression equation, which uses PGA, PGV, Arias intensity of the ground motion and the fundamental period of soil layer, is shown to provide a reliable estimate of the sliding displacement. Furthermore, the empirical equation is shown to reliably predict the hazard category.

• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.217-228
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• 2019

In this study, a seismic vulnerability map of Gyeongju city, where the 9.12 Gyeongju earthquake occurred, was produced and evaluated using analytic hierarchy process(AHP) and geographic information system (GIS). Geotechnical, physical, social, structural, and capacity factors were selected as the main indicators and 18 sub-indicators to construct a spatial database. Weights derived using the AHP were applied to the 18 sub-indicators, which generated a vulnerability map of the five main indicators. After weighting the five generated maps, we created seismic vulnerability maps by overlaying each of the five maps. The seismic vulnerability map was classified into five zones, i.e., very high, high, moderate, low, and safe. For seismic vulnerability, the results indicated that 3% of Gyeongju area is characterized as having very high vulnerability, while 19% was characterized as safe. Based on district standards, Jungbu-dong, Hwangoh-dong, Hwangseong-dong, Seonggeon-dong, and Dongcheon-dong were high-risk areas, and Bodeok-dong, Gangdong-myeon, Yangbuk-myeon, Yangnam-myeon, and Oedong-eup were characterized as safe areas. The seismic vulnerability map produced in this study could possibly be used to minimize damage caused by earthquakes and could be used as a reference when establishing policies.

• Journal of Korean Society of Forest Science
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• v.112 no.3
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• pp.382-392
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• 2023

Recent reports have indicated a rapid increase in the frequency of sediment disasters due to climate change and other changes in the geological environment. Given this alarming situation and the recent increase in the frequency of land creep in Korea, systematic and efficient recovery and management of land creep areas is essential. The purpose of this study is to identify disaster vulnerability by conducting a physical exploration of land creep in San 4-1, Jayeon-ri, Gaegun-myeon, Yangpyeong-gun, Gyeonggi-do, and examine stability by identifying the overall geological structure of the affected ground. In addition, drilling surveys are conducted to verify the reliability of the measured data. The results of the study reveal that low specific resistance abnormalities are distributed in the upper part of the soil layer and weathering zone and that this section is a 50-120 m exploration line. It is also confirmed to be a low-hardness ground area where tensile cracks are observed. Therefore, there is a need for research focused on developing measures to reduce economic and social damage within the domestic context by continuously monitoring indicators of land creep and identifying land creep risks.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.916-923
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• 2023

Purpose: Looking at the status of fatal accidents in the construction industry in the 2022 Industrial Accident Status Supplementary Statistics, 27.8% of all fatal accidents in the construction industry are caused by construction equipment. In order to overcome the limitations of tours and inspections caused by the enlargement of sites and high-rise buildings, we plan to build a model that can extract construction equipment using computer vision technology and analyze the model's accuracy and field applicability. Method: In this study, deep learning is used to learn image data from excavators, dump trucks, and mobile cranes among construction equipment, and then the learning results are evaluated and analyzed and applied to construction sites. Result: At site 'A', objects of excavators and dump trucks were extracted, and the average extraction accuracy was 81.42% for excavators and 78.23% for dump trucks. The mobile crane at site 'B' showed an average accuracy of 78.14%. Conclusion: It is believed that the efficiency of on-site safety management can be increased and the risk factors for disaster occurrence can be minimized. In addition, based on this study, it can be used as basic data on the introduction of smart construction technology at construction sites.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.2
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• pp.34-44
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• 2024

Recently, due to abnormal climate caused by climate change, natural disasters such as floods, landslides, and soil outflows are rapidly increasing. In Korea, more than 63% of the land is vulnerable to slope disasters due to the geographical characteristics of mountainous areas, and in particular, Quarry mines soil and rocks, so there is a high risk of landslides not only inside the workplace but also outside.Accordingly, this study built a DEM using UAV and aviation LiDAR for monitoring the quarry, conducted a time series change analysis, and proposed an optimal DEM construction method for monitoring the soil collection site. For DEM construction, UAV and LiDAR-based Point Cloud were built, and the ground was extracted using three algorithms: Aggressive Classification (AC), Conservative Classification (CC), and Standard Classification (SC). UAV and LiDAR-based DEM constructed according to the algorithm evaluated accuracy through comparison with digital map-based DEM.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.192-199
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• 2024

Wave overtopping is a significant natural hazard that occurs in coastal areas, primarily driven by high waves, particularly those generated during typhoons, which can cause coastal flooding. The development of residential and commercial areas along the coast, driven by increasing social and economic demands, has led to a concentration of people and assets in these vulnerable areas. This, coupled with long-term sea level rise and an increase in typhoon frequency, has heightened the risk of coastal hazards. Traditionally, the evaluation of wave overtopping volumes has relied on directly measuring the collected volume of water that exceeds the crest height of structures through hydraulic model experiments. These experiments are averaged over a specific measurement period. However, in this study, we propose a new method for estimating individual wave overtopping volumes. We utilize the temporal variation of wave overtopping heights to develop an observation system that can quantitatively assess wave overtopping volumes in actual coastal areas. To test our method, we conducted hydraulic model experiments on rubble mound breakwaters, which are commonly installed along the Korean coast. We introduce wave overtopping discharge coefficients, assuming that the inundation velocity from the structure's crest is the long-wave velocity. We then predict overtopping volumes based on wave overtopping heights and compare and review the results with experimental data. The findings of our study confirm the feasibility of estimating wave overtopping volumes by applying the overtopping discharge coefficients derived in this study to wave overtopping heights.

• The Journal of the Petrological Society of Korea
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• v.25 no.4
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• pp.361-372
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• 2016

Lahar, one of catastrophic events, has the potential to cause the loss of life and damage to infrastructure over inhabited areas. This study using Laharz_py program, was performed schematic prediction on the impact area of lahar hazards at the Mt. Halla volcano, Jeju island. In order to comprehensively address the impact of lahar for the Mt. Halla, two distinct parameters, H/L ratio and lahar volume, were selected to influence variable for Laharz_py simulation. It was carried out on the basis of numerical simulation by estimating a possible lahar volumes of 30,000, 50,000, 70,000, 100,000, 300,000, $500,000m^3$ according to H/L ratios (0.20, 0.22 and 0.25) was applied. Based on the numerical simulations, the area of the proximal hazard zone boundary is gradually decreased with increasing H/L ratio. The number of streams which affected by lahar tended to decrease with increasing H/L ratio. In the case of H/L ratio 0.20, three streams (Gwangryeong stream, Dogeun stream, Han stream) in the Jeju-si area and six streams (Gungsan stream, Hogeun stream, Seohong stream, Donghong stream, Bomok stream, Yeong stream-Hyodon stream) in the Seogwipo-si area are affected. In the case of H/L ratio 0.22, two streams (Gwangryeong stream and Han stream) in the Jeju-si area and five streams (Gungsan stream, Seohong stream, Donghong stream, Bomok stream, Yeong stream-Hyodon stream) in the Seogwipo-si area are affected. And in the case of H/L ratio 0.25, two streams (Gwangryeong stream and Han stream) in the Jeju-si area and one stream (Yeong stream-Hyodon stream) in the Seogwipo-si area are affected. The results of this study will be used as basic data to create a risk map for the direct damage that can be caused due to volcanic hazards arising from Mt. Halla.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3B
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• pp.193-201
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• 2012

In the last decade, heavy rainfall induced debris flow events have been remarkably occurred in Korea. Consequently, debris flow is becoming one of the most dangerous natural phenomena in mountainous area. Understanding and correct predicting of the runout distance of debris flow is an essential prerequisite for developing debris flow hazard map and prevention technology. Based on the simple and widely used sled model, in this study, we analyse the net efficiency of debris flows which is a dimensionless constant (=1/R) and defined by the ratio of the horizontal runout distance L from the debris flow source to deposit and the vertical elevation H of the source above the deposit. The analysis of field data observed in total 238 debris flow events occurred from 2002 to 2011 reveals that the representative value of the net efficiency of debris flows in Korea is 4.3. The data observed in Gangwon province where is the most debris flow-prone area in Korea shows that debris flows in Inje area have the runout distance longer than those in Pyongchang and Gangneung. Overall features of the net efficiency of debris flows observed in the central Korea are similar to those in the southern Korea. The estimation based on aerial photographs and available depositional conditions appears to overestimate the net efficiency compared to estimation based on the field observations, which indicates that appropriate depositional conditions need to be developed for debris flows in Korea.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.57-70
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• 2015

Recently, soil erosion have been thickening from heavy rainfall according to climate change. These soil erosion is main reason to cause landslide, the water quality, agricultural counterproductivity and so on. Therefore, it is important to find out the main source area to cause soil erosion using geospatial data including DEM, soil map and land cover those are very sensitive to soil erosion modeling. This study evaluated soil erosion using RUSLE model. Hyoja 4-Dong and Pyonghwa 2-Dong among Wansan-Gu showed high as 10,869 ton/yr and 10,477 ton/yr respectively and Ua 2-Dong of Deokjin-Gu showed high as 17,603 ton/yr in soil erosion. And Hyoja 1-Dong and Pyonghwa 1-Dong among Wansan-Gu showed high as $1,485.7ton/km^2$ and $1,297.0ton/km^2$ respectively and Inhu 3-Dong of Deokjin-Gu showed high as $2,557.7ton/km^2$ in unit soil erosion that was applied to the evaluation of soil erosion potential. It is anticipated that achievement of this study can apply to forecast and prepare the risk of soil erosion and debris flow in urban area.