• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.33-40
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• 2008

Intensive rainfalls in wet season (June~September) result in serious flood damage which is about 95% of natural hazard in Korea. Recently, in order to cope with repeated flood hazard, comprehensive flood control plans have been carried out in large basins in Korea. The plans suggest structural alternative plans for flood mitigation as well as non-structural plans. In this study, a practical method using a decision tree was developed to systematically allocate structural facilities for flood control, which maximizes the flood control capacity in a basin. This study also presents a practical guidance to organize structural defensive alternatives for a comprehensive flood control plan in a large basin.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.77-83
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• 2020

The technologies of 3D spatial information, such as Smart City and Digital Twins, are developing rapidly for managing land and solving urban problems scientifically. In this construction of 3D spatial information, an object using aerial photo images is built as a digital DB. Realistically, the task of extracting a texturing image, which is an actual image of the object wall, and attaching an image to the object wall are important. On the other hand, occluded areas occur in the texturing image. In this study, the ResNet algorithm in deep learning technologies was tested to solve these problems. A dataset was constructed, and the street tree was detected using the ResNet algorithm. The ability of the ResNet algorithm to detect the street tree was dependent on the brightness of the image. The ResNet algorithm can detect the street tree in an image with side and inclination angles.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.1
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• pp.69-80
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• 2021

The new town in Korea, developed as a large-scale housing plan, has created urban ecological corridors to provide habitat and movement routes to wildlife and to promote natural ecological flow. This study aimed to investigate the use of wildlife in 10 ecological corridors in Gwanggyo New Town through camera trap technology and confirm effectiveness by identifying environmental factors affecting the use of wildlife's urban ecological corridors. Our researchers installed 20 unmanned sensor cameras at each the entrance and exit of the ecological corridors, and monitored urban wildlife for 10 weeks. According to the monioring results, the main species in Gwanggyo New Town were identified not only raccons, cats, water deer, korean hare and avain but also magpies, dove, eurasian tree sparrow, ring-necked pheasant, and eurasian jay. The number of uses ecological corridors of urban residents was 801(13.49%), as high as that of urban wildlife (1,140, 19.20%), which was judged to have disturbed the use of ecological corridors by wildlife. However, most dominant species of urban wildlife are nocturnal so that, it was judged that they share home range with urban residents at a time interval. In addition, according to the correlation analysis results between the mammal using rate of the urban ecological corridors and environmental factors(ecological corridor-specific length, ecological corridor-specific width, cover degree, shielding degree, connected green area, separation of movement routes, and presence of streetlights), environmental factors were not statistically significant. However, the more the area of green space connected to ecological corridors, the more increasing the mammal using rate of ecological corridor(r=0.71, p<0.05). Therefore, the area of green space connected to the ecological corridors that is associated with rate of wildlife using corridors should be considered as a priority when developing an urban ecological corridors. In the future, this study will extend the observation period of the ecological corridors and continuously accumulate data by adding the number of observation cameras. Furthermore, it is expected that the results of this study can be used as basic data for the standards for urban ecological corridors installation.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.371-384
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• 2023

We investigated the occurrence of insect pests on street trees that were planted or naturally grew in a total of six urban and suburban parks (two sites in Iksan, one site in Gimje and three sites in Gwangju) in Honam region, South Korea from May to September, 2022. The six survey sites are divided into three characters, two 'nearby forest (NF)', two 'nearby river (NR)' and two 'nearby downtown (ND)' according to the created location of sites and the results on fauna of insect pests compared with street tree species for each character of survey sites. As results, we could discover 51 species of 49 genera in 27 families belonging to five insect orders from a total of 21 tree species belonging to 13 families in six survey sites. Among the insect taxa, hemipteran pests are most diverse with 22 species of 20 genera in 12 families and it is confirmed that Prunus × yedoensis Matsum. (Rosaceae) is damaged by most diverse 25 insect pests. With regard to character of survey sites, trees in 'nearby river' were affected by most diverse 34 insect pests, even though tree species were few compare to sites of 'nearby forest' and 'nearby downtown. Among the affected area of tree parts, leaf-feeding insect pests are most diverse with 22 species. From the present study, we provided a checklist of insect pests from the street trees and selected six most concerned species. Indeed, it is needed to conduct sustainable surveys and monitoring on occurrence of insect pests from street trees in urban and suburban parks because the species of planted street trees in parks can be extremely diverse with occurrence of unexpected insect pests.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.281-293
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• 2011

We investigated the causes and characteristics of a landslide at Hwangryeong Mountain, Busan, based on aerial photos, annual precipitation data, rock fracture patterns, and geomorphic features using GIS Software, and a statistical analysis of tilted trees. The analyzed slope shows evidence of a previous slope failure event and the possibility of future failures. Although the NW-SE trending slope was relatively stable until 1975, a large-scale slope failure occurred between 1975 and 1985 due to complex factors, including favorably oriented geologic structures, human activity, and heavy rain. This indicates that a detailed study of geologic structures, slope stability, and rainfall characteristics is important for slope cuttings that could be a major factor and cause of urban landsliding events. The statistic analysis of tilted trees shows a slow progressive creeping type of mass wasting with rock falls oblique to the dip of the slope, with the slope having moved towards the west since 1985. A concentration of tree tilting has developed on the northwestern part of the slope, which could reach critical levels in the future. The analysis of deformed trees is a useful tool for understanding landslides and for predicting and preventing future landslide events.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.6
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• pp.351-361
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• 2021

The seriousness of fire is rising because fire causes enormous damage to property and human life. Therefore, this study aims to predict various risk factors affecting fire by fire type. The predictive analysis of fire factors was carried out targeting Gyeonggi-do, which has the highest number of fires in the country. For the analysis, using machine learning methods SVM (Support Vector Machine), RF (Random Forest), GBRT (Gradient Boosted Regression Tree) the accuracy of each model was presented with a high fit model through MAE (Mean Absolute Error) and RMSE (Root Mean Squared Error), and based on this, predictive analysis of fire factors in Gyeonggi-do was conducted. In addition, using machine learning methods such as SVM (Support Vector Machine), RF (Random Forest), and GBRT (Gradient Boosted Regression Tree), the accuracy of each model was presented with a high-fit model through MAE and RMSE. Predictive analysis of occurrence factors was achieved. Based on this, as a result of comparative analysis of three machine learning methods, the RF method showed a MAE = 1.765 and RMSE = 1.876, as well as the MAE and RMSE verification and test data were very similar with a difference between MAE = 0.046 and RMSE = 0.04 showing the best predictive results. The results of this study are expected to be used as useful data for fire safety management allowing decision makers to identify the sequence of dangers related to the factors affecting the occurrence of fire.

• Journal of Korean Society of Forest Science
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• v.112 no.1
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• pp.57-70
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• 2023

In recent years, the frequency of warnings about particulate matter (PM) has gradually increased in Korea, along with an increase in its intensity. Because of their vast surface area, reactivity to external particles, and characteristics of their leaves, urban trees can act as biofilters, reducing PM pollution. However, the air pollutant PM can cause various types of damage not only to human health but also to vegetation. Studies performed to date on the responses of trees to PM are still insufficient. Here, we analyzed the correlation between PM adsorption and physiological and biochemical responses of four major street tree species, namely, Abies holophylla, Acer buergerianum, Pinus densiflora, and Quercus variabilis, under conditions of approximately 300 ㎍ m^-3 of fly ash emissions using a phytotron. The results showed that the physiological and biochemical responses and PM adsorption differed depending on the tree species. In correlation analysis, it was confirmed that there were positive correlations between physiological factors, and PM adsorption on adaxial leaf surfaces negatively impacted the physiological characteristics. This study provides fundamental information for selecting tree species to reduce PM pollution and develop sustainable urban forests.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.2
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• pp.219-228
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• 1998

This study was investigated a optimum planting density of urban public park in seoul. Eight species commonly usd as landscape plants were selected. The survey was conducted to measure hight and width of the trees by five years interval. The results are summarized as follows. The average annual growth rates of the trees after planting were 7.4% in height 11.7% in width. Faster grown trees than average growth rate of the survey tres wee Metasequoia, glyptostroboides and Acer buergerianum, While the slower grown trees were Pinus koraiensis, Ginkgo biloba and Zelkova serrata. The average grown trees were Pinus strobus, Pinus densiflora and Acer palmatum . The planting density of survey area was 0.20tree/$m^2$. The optimum planting density was kept until five years after planting, however overcrowding density was found beyond five years after planting. This study also found the density of ten years after planting reaches about 3 times of optimum density.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.77-80
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• 2004

In this study the spatial distribution characters of burnt forest site was first considered by analyzing spatial data and monitoring forest landscape before/after lire to restore the site. Then suitable tree species on each forest site should be selected through the weighted score analysis of GIS analysis methods. Finally. the best forest stand arrangement method could be simulated on the system for the advanced reforestation technology in Korea. For this purpose, the virtual reforestation system was implemented by using the concept of virtual GIS and CBD (Component Based Development) method. By use of this system the change of forest landscape of burnt forest area some years after reforestation practice could be detected and monitored by applying the site index and 3D modeling method.

• Journal of the Korea Safety Management & Science
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• v.13 no.1
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• pp.51-58
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• 2011

The uniformity of lighting distribution on the roadway is essential factor for drivers and pedestrians's safety during nighttime in urban streets. Also, the importance of roadside trees is one of the growing concern for better citizens' health and mitigating environmental impact on the urban street. But roadway lightings and roadside trees have different design or planting standards and they are not integrated in the systemic viewpoint for better safety of users during nighttime. The purpose of this study is to propose a simulation approach which assesses lighting quality in the view of illumination uniformity distribution of roadway lighting from design step and consider the layout of roadside trees. For improving lighting quality of roadway, simulation approach is needed for assessing the impact of diverse planting situation of trees and encouraged from beginning of design step for roadway construction.