• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.299-316
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• 2019

The purpose of this study was to analyze landslide susceptibility in the Pyeongchang area using Weight of Evidence (WOE) and Evidential Belief Function (EBF) as probability models and Artificial Neural Networks (ANN) as a machine learning model in a geographic information system (GIS). This study examined the widespread shallow landslides triggered by heavy rainfall during Typhoon Ewiniar in 2006, which caused serious property damage and significant loss of life. For the landslide susceptibility mapping, 3,955 landslide occurrences were detected using aerial photographs, and environmental spatial data such as terrain, geology, soil, forest, and land use were collected and constructed in a spatial database. Seventeen factors that could affect landsliding were extracted from the spatial database. All landslides were randomly separated into two datasets, a training set (50%) and validation set (50%), to establish and validate the EBF, WOE, and ANN models. According to the validation results of the area under the curve (AUC) method, the accuracy was 74.73%, 75.03%, and 70.87% for WOE, EBF, and ANN, respectively. The EBF model had the highest accuracy. However, all models had predictive accuracy exceeding 70%, the level that is effective for landslide susceptibility mapping. These models can be applied to predict landslide susceptibility in an area where landslides have not occurred previously based on the relationships between landslide and environmental factors. This susceptibility map can help reduce landslide risk, provide guidance for policy and land use development, and save time and expense for landslide hazard prevention. In the future, more generalized models should be developed by applying landslide susceptibility mapping in various areas.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.565-572
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• 2018

Recently, UAVs (Unmanned Aerial Vehicles) or drones have gained popularity for the engineering surveying and mapping because they enable the rapid data acquisition and processing as well as their operation cost is low. The applicable fields become much wider including the topographic monitoring, agriculture, and forestry. It is reported that the high geospatial accuracy is achievable with the drone photogrammetry for many applications. However most studies reported the best achievable mapping results using well-distributed ground control points though some studies investigated the impact of control points on the accuracy. In this study, we focused on the drone mapping of corridors such as roads and pipelines. The distribution and the number of control points along the corridor were diversified for the accuracy assessment. In addition, the effects of the camera self-calibration and the number of the image strips were also studied. The experimental results showed that the biased distribution of ground control points has more negative impact on the accuracy compared to the density of points. The prior camera calibration was favored than the on-the-fly self-calibration that may produce poor positional accuracy for the case of less or biased control points. In addition, increasing the number of strips along the corridor was not helpful to increase the positional accuracy.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.189-199
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• 2019

The forest management paradigm has recently shifted from focusing on commercial production to focusing on ecosystem management. Accordingly, a natural seedling regeneration method that has a naturally high affinity has attracted much attention in recent years. The aim of this study was to determine the relationship among various environmental factors, lower stratum vegetation, and seedling regeneration in Pinus densiflora forests. The survey site comprised 50 sectors divided using the line transect method, and the survey data were divided into those from wet habitat (19 sites) and dry habitat (31 sites), depending on the soil humidity, and were analyzed separately to show the close relationship between soil humidity and natural seedling regeneration. As a result, the dry habitat exhibited high seedling density (157,419 trees/ha), with the main species being Quercus serrata, Zanthoxylum piperitum, Smilax china, and Pueraria lobata, while wet habitat exhibited low seedling density (57,895 trees/ha), with the main species being Stephanandra incisa, Castanea crenata, Lespedeza maximowiczii, Lysimachia barystachys, Aralia elata, and Styrax japonicus. The height and root-collar diameter under wet conditions exhibited faster growth than those under dry conditions. Height growth by the root-collar diameter in dry habitat increased faster than that in wet habitat. It was also confirmed that seedling regeneration in wet habitat exhibited a rapid growth pattern 5 years after germination. These results suggest that the seedlings begin to grow more rapidly after a period of suppression by competition with surrounding plants. Considering an ecosystem or ecological management approach, specific practices, such as bush control and vine clearing in wet habitats, should be more intensively conducted, especially at the beginning of the management operations.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.3
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• pp.51-64
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• 2019

Mt. Geumgang has been a scenic spot representing the Korean peninsula since the Joseon Dynasty, and became a symbol of inter-Korean exchanges with the Gaesong Industrial Complex after the division of the South and North. Mt. Geumgang Tour Course is divided into the Inner-Geumgang (Naegeumgang) and the Outer-Geumgang (Oegeumgang). It was common for the Mt. Geumgang tour route during the Joseon Dynasty and the Japanese Imperialization period to enter the Inner-Geumgang, near Seoul, and come to the East Sea through the Outer-Geumgang. However, the tour route starting from Goseong was utilized for the Mt. Geumgang tour course operated by Hyundai. Because North Korea opened only the Outer-Geumgang area. North Korea has only opened some of its tour courses to Hyundai, but if Geumgang tourism is resumed in the future, there is a high possibility that it will be opened further, such as opening some sections of the Inner-Geumgang in 2007. In this case, it is necessary to connect additional transportation networks to access Inner-Geumgang from South Korea. The best alternative was the restoration of the Mt. Geumgang Railway. However, considering the fact that the reconstruction of the Mt. Geumgang Railway can not be completed due to the construction of the Imnam Dam, it is the most realistic alternative to restore Route 31 connecting Yanggu and Geumgang-eup. As a result of the analysis of road connecting Inner-Geumgang, three routes were confirmed. All of which were adjacent to the existing National Route 31. These routes passing through Dutayeon and Mundeung-ri and joining the Route 31 from Inje. Considering road length, topography characteristics, and military facility layout, it seems that the connection of 'Dutaeyun - Mundeung - Geumgang' is a realistic alternative connecting from South Korea to Inner-Geumgang.

• The Journal of the Acoustical Society of Korea
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• v.38 no.2
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• pp.161-167
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• 2019

In this paper, the performance verification of an around-view sonar and an excavation depth measuring sonar applicable to track-based ROVs (Remotely Operated underwater Vehicles) for heavy duty work is studied. For the performance verification, an experiment is carried out in a water tank and at sea by attaching the around-view sonar and the excavation depth measuring sonar for a heavy work ROV. In the case of the around-view sonar, image sonars are mounted on ROV in four directions (front, back, left and right) and in the case of the excavation depth measuring sonar, the same kind of MBES (Multi Beam Echo Sounder) is mounted on the front of the ROV. The result of an operation test of the ROV equipped with these sonars shows that the sonar systems are rarely affected by high turbidity due to sedimentation during the operation. In the case of the around-view sonar, it is possible to see rock formation, gravel and sandbank 30 m ahead of the ROV. It is confirmed that the excavation depth can be measured after the ROV has performed the excavation. This experiment demonstrates that the ROV can improve the efficiency of the work by utilizing the around-view sonar and the excavation depth measuring sonar.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.2
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• pp.282-297
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• 2019

Detection of mesoscale oceanic eddies using satellite data can utilize various ocean parameters such as sea surface temperature (SST), chlorophyll-a pigment concentration in phytoplankton, and sea level altimetry measurements. Observation methods vary for each satellite dataset, as it is obtained using different temporal and spatial resolution, and optimized data processing. Different detection results can be derived for the same oceanic eddies; therefore, fundamental research on eddy detection using satellite data is required. In this study, we used ocean color satellite data, sea level altimetry data, and infrared SST data to detect mesoscale eddies in the East Sea and compared results from different detection methods. The sea surface current field derived from the consecutive ocean color chlorophyll-a concentration images using the maximum cross correlation coefficient and the geostrophic current field obtained from the sea level altimetry data were used to detect the mesoscale eddies in the East Sea. In order to compare the eddy detection from satellite data, the results were divided into three cases as follows: 1) the eddy was detected in both the ocean color and altimeter images simultaneously; 2) the eddy was detected from ocean color and SST images, but no eddy was detected in the altimeter data; 3) the eddy was not detected in ocean color image, while the altimeter data detected the eddy. Through these three cases, we described the difficulties with satellite altimetry data and the limitations of ocean color and infrared SST data for eddy detection. It was also emphasized that study on eddy detection and related research required an in-depth understanding of the mesoscale oceanic phenomenon and the principles of satellite observation.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.4
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• pp.105-112
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• 2018

This study aims to apply 3D scanning technology to the field of landscape planning design. Through this, 3D scans were conducted on Soswaewon Garden and Seongrakwon Gardens to find directions for traditional landscape planning and designs. The results as follows. First, the actual measurement of the traditional garden through a 3D scan confirmed that a precise three-dimensional modeling of ${\pm}3-5mm$ error was constructed through the merging of coordinate values based on point data acquired at each observation point and postprocessing. Second, as a result of the 3D survey, the Soswaewon Garden obtained survey data on Jewoldang House, Gwangpunggak Pavilion, the surrounding wall, stone axis, and Aeyangdan wall, while the Seongnakwon Garden obtained survey data on the topography, rocks and waterways around the Yeongbyeokji pond area. The above data have the advantage of being able to monitor the changing appearance of the garden. Third, spatial information developed through 3D scans could be developed with a three-dimensional drawing preparation and inspection tool that included precise real-world data, and this process ensured the economic feasibility of time and manpower in the actual survey and investigation of landscaping space. In addition, modelling with a three-dimensional 1:1 scale is expected to be highly efficient in that reliable spatial data can be maintained and reprocessed to a specific size depending on the size of the design. In addition, from a long-term perspective, the deployment of 3D scan data is easy to predict and simulate changes in traditional landscaping space over time.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.36 no.4
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• pp.18-27
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• 2018

This study is a basic one analyzing the scenic characteristics that are created in Royal Garden in China while taking into consideration that Royal Garden in China is a fruit compiling all of the Chinese classical gardens. In case of Summer Palace in China, it adopted various kinds of landscape displaying techniques for fulfilling the desires of an Emperor who wanted to appreciate beautiful landscapes all the time. Accordingly, the scenic characteristics can be summarized as follows. First, Summer Garden creates various kinds of garden landscapes through various kinds of landscape creation techniques, such as, Borrowed Landscape, Central One, Background One, Symmetrical One, Axial One, Dividing One, Framed One, Window One and Complementing One, etc. Second, it was created in order for visitors to focus on appreciation of landscapes by allocating hard points while considering the symmetric structure, Structure of Long Corridor and Visual Physiology of a building on the basis of the South-North Pivotal Line. Third, it utilized the scenic spot transferring technique that introduces the landscapes of scenic spots in various regions of China to Summer Palace to be matched to the unique geological characteristics of Summer Garden. It was found that Summer Palace adopted the common landscaping techniques in Jiangnan Region of Ancient China since the landscape of Jichang Garden in Hangzhou and that of Shan Tang Jie in Suzhou are reproduced and transferred. It was found that 3 methods mentioned above have the effects that attract sightseers' eyes naturally and make their interests concentrated as well as reviving the feeling of space in a garden and creating abundant scenic beauty.

• Journal of the Korean Society of International Agriculture
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• v.30 no.4
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• pp.285-291
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• 2018

The System of Rice Intensification (SRI) has been spread very quickly in southern Cambodia. To understand the motivation of farmers in adapting SRI, and its benefits, we conducted an on-farm study at Popel commune, Tramkak district, Takeo province in southern Cambodia, during the 2012 and 2013 wet season. We noticed a significant difference between SRI and conventional farmers' practices (FP) in rainfed lowland rice ecosystem. Despite of low nitrogen input, without chemical fertilizers, high grain yield was achieved in SRI 1 (6.0 t ha) and SRI2-Bottom ($7.2t\;ha^{-1}$) in 2013. SRI 1 and SRI 2 of panicle and number of panicle were high than SR 3, FP 2, and FP 3 due to early transplant. Relationships between total number of spikelet and plant nitrogen were ($r^2=0.95$) highly positive at harvest. SRI fields were, most of them achieving highly superior yield and number of panicle compared to their FP fields. The results indicated that SRI practices of planting younger seedling, with organic material and topography of paddy, lead to increased grain yield.

• Journal of The Geomorphological Association of Korea
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• v.23 no.2
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• pp.47-59
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• 2016

The formation age and depositional environment of the marine terrace I of the estimated paleoshoreline altitude of 18m in Sanhari of Ulsan coast, southeastern Korea were investigated on the basis of examination of lithofacies and stratigraphy of terrace deposits. Marine deposits of the terrace is composed of rounded boulders(70cm in diameter) and rounded pebbles(1.0cm in diameter) which overlay them. The above rounded boulders which lie on the paleo-shore platform are considered to have been formed by wave abrasion in the same period that the paleo-shore platform was developed. The rounded pebbles which lie on the rounded boulder layer are considered to have been deposited in gravel beach and berm environment, judging from the laminae developed in this layer. The paleo-shore platform and marine rounded gravel layer of the terrace are assumed to have been formed in the large transgression period of the Last Interglacial culmination stage(MIS 5e), judging from the comparision of the formation age of 125ka B.P. of Juckcheon terrace I in the adjacent Pohang coast which was dated by amino acid dating. The terrestrial deposit of this terrace was largely composed of angular and subangular gravel mixed with marine rounded pebble which has been carried away mainly from the deposit of previous marine terraces and redeposited in this terrace. The lowest peat layer of terrastrial deposit was considered to have been deposited during the period from the late MIS 5e which is the estimated finishing time of deposition of the above marine gravels to the early stage of following regression period(MIS 5d) in which the sea level was still high. The sediments of angular and subangular gravel deposit which lie on this peat layer were assumed to have been deposited during the period from the early stage of the first regression period(MIS 5d) of the Last Interglacial to the Last Glacial. The lower part of the angular gravel layer is composed of the deposits of the fluvial and colluvial sediments, whereas most of the upper and middle part of the layer is mainly composed of angular gravels of colluvial sediments formed in the cold environment.