• KEPCO Journal on Electric Power and Energy
• /
• v.7 no.2
• /
• pp.285-293
• /
• 2021

The construction of underground structures such as power supply lines, communication lines, utility tunnels has significantly increased worldwide for improving urban aesthetics ensuring citizen safety, and efficient use of underground space. Those underground structures are usually constructed along with vertical cylindrical shafts to facilitate their construction and maintenance. When constructing a vertical shaft through the open-cut method, the walls are mostly designed to be flexible, allowing a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the displacement of the surrounding ground. This study simulated stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model experiment. One quadrant of the axisymmetric vertical shaft and the ground were modeled, and ground excavation was simulated by shrinking the vertical shaft. The deformation occurring on the entire ground during the excavation was continuously evaluated through digital image analysis. The digital image analysis evaluated complex ground deformation which varied with wall displacement, distance from the wall, and ground depth. When the ground deformation data accumulate through the method used in this study, they can be used for developing shaft wall models in future for analyzing the earth pressure acting on them.

• Smart Structures and Systems
• /
• v.30 no.1
• /
• pp.17-34
• /
• 2022

For steel structures, fatigue cracks are critical damage induced by long-term cycle loading and distortion effects. Vision-based crack detection can be a solution to ensure structural integrity and performance by continuous monitoring and non-destructive assessment. A critical issue is to distinguish cracks from other features in captured images which possibly consist of complex backgrounds such as handwritings and marks, which were made to record crack patterns and lengths during periodic visual inspections. This study presents a parametric study on image-based crack identification for orthotropic steel bridge decks using captured images with complicated backgrounds. Firstly, a framework for vision-based crack segmentation using the atrous convolution-based Deeplapv3+ network (ACDN) is designed. Secondly, features on crack images are labeled to build three databanks by consideration of objects in the backgrounds. Thirdly, evaluation metrics computed from the trained ACDN models are utilized to evaluate the effects of obstacles on crack detection results. Finally, various training parameters, including image sizes, hyper-parameters, and the number of training images, are optimized for the ACDN model of crack detection. The result demonstrated that fatigue cracks could be identified by the trained ACDN models, and the accuracy of the crack-detection result was improved by optimizing the training parameters. It enables the applicability of the vision-based technique for early detecting tiny fatigue cracks in steel structures.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.36 no.4
• /
• pp.83-99
• /
• 2008

Images of Seong-Nam appears different according to diverse conditions. This study was intended to analyze the differences of cognition by personal characteristics such as age, gender, location, and period when an individual evaluates an urban image. This research focused on the interpretation of the visualized results from Multidimensional Scaling (MDS) and Individual Difference Scaling (INDSCAL) with two questionnaires. This study can be summarized as follows: 1. Namhan Sansung was ranked as the first symbolic property by citizens in Seong-Nam. Next was Yuldong Park, followed by Bundang Central Park, Seohyun Station including Samsung Plaza, and, finally, Moran Market. This trend also similarly appeared in the selection of preferred places. 2. There were no statistical differences in trends of choice of symbolic landmarks and preferred places according to age, gender, and period; however, there were meaningful differences according to location. 3. The total image of Seong-Nam was positioned to be separated from images of other districts and landmarks on the image spatial plot by MDS; however, images of the old and new district were plotted close to symbolic landmarks where located around each district. 4. INDSCAL illustrated that men weighted the historical meaning while women weighted preference and city size when evaluating an urban image. On the other hand, there was no difference in cognitive trends according to age, location, and period. Until now, an individual difference in the cognition and evaluation of an urban image was a socially accepted notion. However, this study verified the difference according to personal characteristics and developed a practical tool to analyze an individual cognition trend about a city image.

• Korean Journal of Remote Sensing
• /
• v.8 no.1
• /
• pp.27-43
• /
• 1992

The purpose of this study is to detect and evaluate the change of urban vegetation of Seoul during 1980s. Large areas covered with agricultural crops or forests were converted to residential and commercial areas, roads, schools, sports complexes, etc. There were also widespreas concerns on the deterioration of the quality of urban vegetation due to severe air pollution, overcrowding of nature parks, and idling of farm lands by land speculators. The image used for this study were MSS(Oct. 4, 1979) and TM(Apr. 26, 1990). The Green Vegetation Index of Kauth & Thomas(1976) was for the analysis. The GVI were resampled with 75$\times$75m grids and overlaid with the jurisdictional boundaries of 22 districts of Seoul. The results were reclassified to 6 classes, class 6 representing grids with the most vigorous vegetation or the best vegetation improvement in 1980s. The finding of this study can be summarized as follows : First, the most vigorous vigorous vegetation, in terms of GVI, of the 1979 image can be found at paddy fields located on alluvial near Han River. Broad-leaf forests located on hilly terrains have higher GVI than conifers located on the upper-parts of mountains. The average GVI of the northern part and southern part of Han River are 3.56 and 3.74, respectively. The main reason why the southern part has higher GVI is that there are more prime agricultural lands. Districts of Kangseo, Yangcheon, and Songpa have the highest percentage of grids of GVI class 6, and the percentages are 3.55 %, 3.47 %, and 2.69 %, respectively. Second, the most vigorous vegetation of the 1990 image can be found at the grass lands of the Yongsan golf club and the Sungsu horse racing track. The GVI of farm lands is lower than forest because most agricultural crops are at the early stage of growing season when the TM image was taken. The size of built-up area is much larger than of 1979. On the other hand, vegetation patches surrounded by developed area become smaller and have stronger contrast to surrounding area. The average GVI of the northern part and southern part of Han River are 3.57 and 3.51, respectively. The main reason why the southern part has lower GVI is the at more large-scale urban development projects were carried out in there during 1980s. Districts of Tobong, Nowon, and Seocho have the highest percentage of class 6, and the perecentages are 16.58 %, 10.14 %, and 8.50% respectively. Third, the change of urban vegetation in Seoul during 1980s are significant. Grids of GVI change classes 1 and 2, which represent severe vegetation loss, occupy 15.97% of Seoul. Three districts which lost the most vegetation are Yangcheon, Kangseo, and Songpa, where the percentages of GVI class 1 are 13.42%, 13.39% and 9.06%, respectively. The worst deterioration was mainly caused by residential developments. On the other hand, the vegetation of some part of Seoul improved in this period. Grids of GVI change classes 5 and 6 occupy 9.83 % of Seoul. Distircts of Jung, Yongsan, and Kangnam have the highest percentage of grids with GVI change classes 5 and 6, and their percentages are 22.31%, 19.17%, and 13.66%, respectively. The improvement of vegetation occurred in two areas. Forest vegetation is generally improving despite of concerns based on air pollution and heavy use by recreationists. Vegetation in open spaces established in riverside parks, large residential areas, and major public facilities are also improving.

• Asian Journal of Atmospheric Environment
• /
• v.9 no.2
• /
• pp.128-136
• /
• 2015

Sky View Factor (SVF) is one of the urban morfometri parameters that impact on the Urban Heat Island (UHI). SVF analisys was conducted in the city of Jakarta to investigate the relationship between urban temperature with urban morfometri. Jakarta City is the most populous city in the world that has a surrounding area $66,152km^2$ and the total population around 23 million people. The population of the city is the sixth highest in the world today. SVF measurements done by taking pictures at the six stations that have different morphological characteristics namely (1) the narrow streets Apartment Cempaka Mas (JS ITC), (2) the width of the road Apartment Cempaka Mas (JL ITC), (3) in front of Colleges Kanisius (DKK), (4) in front of office Journalist of Indonesia (DKWI), (5) Utan Kayu (UK), and (6) Tambun (TB). SVF value is obtained from the photgraphic image. Taking pictures at the location using a Nikon D90 camera with a Nikon Fisheye Nikkor 10.5 mm 1 : 2.8 G ED, further processed through a global mapper program. Therefore, the SVF derived from the six stations that vary 0.21 to 0.78. Temperature measurement is done during daylight hours from 06:00 am to 18:00 pm during the Western Part of Indonesia (WIB). Measurements performed at three different times, namely working days (HK) regular holidays (HCB) national holidays (HCN). The results showed that the highest average temperature of $33.32^{\circ}C$, occurring at UK station (SVF=0.45) at the time of HCB. Meanwhile, the average low temperature of $31.22^{\circ}C$ occurred at JLITC station (SVF=0.42). The two-time occurred on ordinary holidays. Maximum temperature of $38.4^{\circ}C$ occurred in Utan Kayu station (SFV=0.45) that occurred at 11.00 hrs, normal holidays. Furthermore minimum temperature 24.5 occurred at Tambun station (SVF=0.78) at 06.00 hrs in the morning at the usual holidays and national holidays. In general, the results showed that areas with large SVF has a lower temperature compared with areas with smaller SVF. Though, are not the only factors that matter, but this research may show that an increase in temperature in the city of Jakarta. Therefore, it is necessary to mitigate the serious from the government or society.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_3
• /
• pp.1975-1984
• /
• 2021

Urban expansion results in raising the temperature in the city, which can cause social, economic and physical damage. In order to prevent the urban heat island and reduce the urban land surface temperature, it is important to quantify the cooling effect of the features of the urban space. Therefore, in order to understand the relationship between each object of land cover and the land surface temperature in Seoul, the land cover map was classified into 6 classes. And the correlation and multiple regression analysis between land surface temperature and the area of objects, perimeter/area, and normalized difference vegetation index was analyzed. As a result of the analysis, the normalized difference vegetation index showed a high correlation with the land surface temperature. Also, in multiple regression analysis, the normalized difference vegetation index exerted a higher influence on the land surface temperature prediction than other coefficients. However, the explanatory power of the derived models as a result of multiple regression analysis was low. In the future, if continuous monitoring is performed using high-resolution MIR Image from KOMPSAT-3A, it will be possible to improve the explanatory power of the model. By utilizing the relationship between such various land cover types considering vegetation vitality of green areas with that of land surface temperature within urban spaces for urban planning, it is expected to contribute in reducing the land surface temperature in urban spaces.

• Korea Science and Art Forum
• /
• v.27
• /
• pp.101-114
• /
• 2017

Based on the relationship between urban public space, urban lighting and the sense of place, this paper aims to analyze the lighting environment types with the sense of place and their characteristics. First, with the theory study as the research foundation, it extracts six spatial factors of public space lighting design and then analyzes 12 relevant cases on the basis. Finally, it divides the 12 cases into four types, Basic types, Storytelling, Interactive and Multi-Media and analyzes the core design factor and characteristics of various types. The results show that: first, functionality, sustainability and aesthetics are the basic factors to realize the urban public space lighting places. Second, the six cases of "Storytelling" show that the theme of specific areas, namely the exploration of "story" is conducive for lighting design to form clear and definite environment recognition. Third, for "Interactive" and "Multi-Media", the intervention of new media technology and new lighting way has made the wide expansion of urban lighting design connotation and extension. The research results show that strengthening the urban location performance by the lighting design could improve the city image, which provides the basis for the development of urban public space lighting design.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.6
• /
• pp.110-123
• /
• 2019

Traffic data is the most basic element necessary for transportation planning and traffic system operation. Recently, a method of estimating traffic flow characteristics using distance to a leading vehicle measured by an ADAS camera has been attempted. This study investigated the feasibility of the ADAS vehicle reflecting the distance error of image-based vehicle identification technology as a means to estimate the traffic flow through the normalized root mean square error (NRMSE) based on the number of lanes, traffic demand, penetration rate of probe vehicle, and time-space estimation area by employing the microscopic simulation model, VISSIM. As a result, the estimate of low density traffic flow (i.e., LOS A, LOS B) is unreliable due to the limitation of the maximum identification distance of ADAS camera. Although the reliability of the estimates can be improved if multiple lanes, high traffic demands, and high penetration rates are implemented, artificially raising the penetration rates is unrealistic. Their reliability can be improved by extending the time dimension of the estimation area as well, but the most influential one is the driving behavior of the ADAS vehicle. In conclusion, although it is not possible to accurately estimate the traffic flow with the ADAS camera, its applicability will be expanded by improving its performance and functions.

• Korean Journal of Community Nutrition
• /
• v.23 no.4
• /
• pp.302-318
• /
• 2018

Objectives: This study examined the differences in dietary life and health related factors, such as drinking behavior, exercise and leisure activities, mental health, and subjective perception for oneself according to obesity in poor urban Peruvian adolescents. Methods: A total of 1,532 Peruvian adolescents were selected from six schools in poor regions using stratified random sampling. The subjects were classified into two groups based on their BMI: 'normal weight group (NW group=980)' or 'overweight and obese group (OWOB group=293)'. The differences in the general characteristics, dietary life, drinking behavior, physical activity and leisure, mental health and subjective perception of oneself in the two groups were compared. ${\chi}^2$ analysis and independent sample t-test were performed using the SPSS program ver. 24. Results: For the total and male students, the frequency of breakfast and dinner were significantly lower in the OWOB group than in the NW group (all p<0.001). For total and female students, the percentage of subjects who received nutrition education was significantly higher in the OWOB group than in the NW group (all p<0.05). For total students, the percentage of subject who exercised more than five days/week was lower in the OWOB group than in the NW group (p<0.05). For the total and female students, the subjective health status was worse in the OWOB group than in the NW group (all p<0.05). The subjective body image was significantly different between the OWOB group and NW group in the total, male and female subjects (all p<0.001). Conclusions: The frequency of meals and exercise, and the subjective perceptions of the health status and body image differed according to obesity in poor urban Peruvian adolescents. Therefore, a school-based intervention program focused on regular meal and exercise, and adequate subjective perceptions for health status and body image need to be developed to prevent adolescent obesity.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.25 no.2
• /
• pp.88-99
• /
• 2022

The river network is one of the essential topographical characteristics in river management. The river network which as previously constructed by the ground surveying method has recently begun to be efficiently constructed using the remote sensing datasets. Since it is difficult to remove these obstacles such as bridges in the urban rivers, it is rare to construct the urban river networks with the various obstacles. In this study, the Sentinel-2 satellite imagery was used to develop the automatic method for detecting the urban river networks without the obstacles and with the preserved boundaries as follows. First, the normalized difference water index image was generated using the multispectral bands of the given Sentinel-2 satellite imagery, and the binary image that could classify the water body and other regions was generated. Next, the morphological operations were employed for detecting the complete river networks with the obstacles removed and the boundaries preserved. As a result of applying the proposed methodology to Han River in Seoul, the complete river networks with the obstacles removed and the boundaries preserved were well constructed.