• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.421-431
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• 2007

The main purpose of this study is to develop a sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing one of the carbon or glass chopped fibers and one of the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In order to investigate the material property of the sprayed FRP, this study carried out tensile tests of the material specimens, which were changed with the combinations of various variables including the length of chopped fiber and the mixture ratio of chopped fiber and resin. These variables were set to have the equal material strength, compared with that of one layer of the FRP sheet. As a result, the optimal length of glass and carbon chopped fibers was fumed out to be 38 mm, and the optimal mixture ratio between chopped fiber and resin was also turned out to be 1 : 2 from each variable. And also, the thickness of the sprayed FRP to have the equal strength to one layer of the FRP sheet was finally calculated. In is study, a series of experiments were carried out to evaluate the strengthening effects of flexural beams, shear beams and damaged beams strengthened with the sprayed FRP method, respectively. The results revealed that the strengthening effects of the flexural and shear specimens were reasonably similar to those of the FRP sheet, and the developed Sprayed FRP technique is able to be used as a strengthening scheme of existing RC building.

• Ecology and Resilient Infrastructure
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• v.7 no.1
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• pp.1-14
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• 2020

In fluvial and riparian ecosystems, biogeomorphological research has considered the complex, multi-way relationships between biological and hydro-geomorphological components over a wide range of spatial and temporal scales. In this review, we discussed the scope and processes of fluvial biogeomorphology by explaining (1) the multi-lateral interactions between organisms and hydrogeomorphic conditions, (2) the relationships between biodiversity and habitat heterogeneity, and (3) the effects of disturbance on ecosystem patterns. Over time, an organism-landform complex along streams transitions in the sequences of geomorphic, pioneer, biogeomorphic, and ecological stages. Over space, water flow and sediment distributions interact with vegetation to modify channel topography. It is the habitat heterogeneity in streams that enhances riparian biodiversity. However, in the areas downstream of a dam, habitat types and conditions are substantially damaged and biodiversity should be reduced. In South Korea, riparian vegetation flourishes in general and, in particular, invasive species actively colonize in accordance with the changes in the fluvial conditions driven by local disturbances and global climate change. Therefore, the importance of understanding reciprocal relationships between living organisms and hydrogeomorphic conditions will ever increase in this era of rapid climate change and anthropogenic pressure. The fluvial biogeomorphic framework reviewed in this article will contribute to the ecological management and restoration of streams in Korea.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.31 no.2
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• pp.31-42
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• 2013

A purpose of this study, after identifying the status and type of changes derived elements that make up the Seowon(書院); landscape space and the space of the during the recent World Heritage, focusing promote the newly introduced trees listed in the important value, authenticity and integrity aspects The results can be summarized as follows. The results can be summarized as follows. Appeared trees in various old documents are 10 species; Prunus persica (L.) Batsch, Prunus mume(Siebold) Siebold & Zucc., Salix koreensis Andersson. The planting space shows regularity of some degree depends on the status of the species, essentially 3 types of Juniperus chinensis L., Lagerstroemia indica L., Phyllostachys nigra(Lodd.) Munro are primarily located in inside of seowon(書院), Zelkova serrata (Thunb.) Makino., Salix koreensis Andersson is in out side of seowon(書院). 5 types of location space to species such as Juniperus chinensis L., Ginkgo biloba L. species are the most frequently appear and it can be national representative trees. Plants which have limited vitality is a factor to prove a history of seowon(書院), it is accord with authenticity aspects that it gives meaning of symbolic to canonized figure's preference Maintenance work carried out over the years has damaged to origin of tree and thoughtlessly planted without having to go through a thorough historical research has resulted in weakening the presence of the essential space. It should preserve to features originally it have is figure reflect the viewpoint of the transformed current private to reveal the history of the various places. In conclusion, this research continues to study at the spatial dimension like a building in limited to panted, and also determine the intrinsic value of the overall spatial configuration.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.6
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• pp.11-21
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• 2010

This study presents seismic responses of 5-story reinforced concrete structures retrofitted with the buckling-restrained braces using a time-dependent element. The time-dependent element having birth and death times can freely be activated within the user defined time intervals during the time history analysis. The buckling-restrained brace that showed the largest energy dissipation capacity among the test specimens in previous research was used for retrofitting the RC buildings in this study. It was assumed that the first story of the damaged building under the first earthquake was retrofitted with the buckling-restrained braces considered as the time-dependent element before the second of the successive earthquakes occurs. Under this assumption, this paper compares seismic responses of the RC structures with the time-dependent element subjected to the successive earthquake. Subjected to the second earthquake, it was observed that activation of the BRB systems largely decreases deformation of the moment frame where the damage was concentrated under the first earthquake. However, damages to the shear wall systems were increased after activation of the BRB systems. Since the cumulative damages of the shear wall systems were infinitesimal compared with the retrofit effect of the moment frame, the BRB system was effective under the successive earthquake.

• Spatial Information Research
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• v.17 no.3
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• pp.341-350
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• 2009

As the power and scale of typhoons are growing due to global warming and socioeconomic damages induced by super-typhoons are increasing, it is important to estimate inundation damages and to prepare proper adaptation plans against an attack of the super-typhoon. In this paper, we estimated the inundation damages of urban area around Haeundae beach induced by super-typhoons which follow the route of Typhoon Maemi with the conditions of Typhoon Vera (Ise Bay in Japan, 1959), Typhoon Durian (Philippine, 2006) and Hurricane Katrina (New Oleans in U.S.A, 2005). The coastal area around the Haeundae beach (Busan and Gyeongnam province) is expectedly damaged by severe storm surges. In this study we calculated the rise of sea level height after harmonizing the different datum levels of land and ocean and estimated the inundation depth, inundation area and the amount of building damages by using airborne LiDAR data and GIS spatial analysis techniques more accurately and quantitatively. As many researchers are predicting that super-typhoon of overwhelming power will occur around the Korean peninsula in the near future, the results of this study are expected to contribute to producing coastal inundation map and evacuation planning.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.4
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• pp.43-55
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• 2017

The purpose of this study is to investigate conservation and management methods of the Joseon Royal Tombs in the Middle District. Urbanization has damaged many of the original terrains as many buildings and facilities have entered the inner and outer area of Joseon Royal Tombs. Land purchase, relocation and demolition of the building are required for the recovery of the Royal Tombs area, and then it is necessary to recover the original terrain. In the case of land use and pathways, there were many land use which harmed the sacred atmosphere of the area, and many disconnection of the ritual circulation, they should be maintained to remind the sacred atmosphere of the royal tomb. The water system should be changed to natural type canal, and it is necessary to collect accurate information on the lost buildings and stoneworks through literature survey and excavation investigation, and then lead to the exposure or restoration of the ruins. Historical forests require periodic and ongoing monitoring and management, and it is necessary to establish a historical and cultural museum that can provide to visitors information about Joseon Royal Tombs. These works should be classified into short, medium and long-term projects with a long perspective to implement continuous and systematic projects.

• Korean Journal of Heritage: History & Science
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• v.46 no.2
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• pp.26-45
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• 2013

Sudden increase exceeding 30million in the number of smart phone users, and rising interest in the technology of augmented reality, is now trying to combine it with AR technology in other areas very much. The field of cultural heritage, which has been constructed by the Internet and 3D technology, is not unusual and this field is now rapidly changing thanks to the AR technology which can make users experience cultural heritage with high reality. The Palaces in Seoul, however, use fragmentary tools of information - lack of heritage commentators, leaflet, etc, even though the number of visitors is gradually increasing. Therefore, three-dimensional and comprehensive cultural heritage information service is needed with the guidance in the mobile era. This study utilizes the AR technology for building the Deoksugung Tourist Information Service Application(App.) applying the markerless-based recognition technology which is a more advanced tool than the location-based AR technology. This new AR technology can switch perceived real images such as the tablet of the King in the Palace of in the real world, patterns and pedestals into virtual world, which can reproduce the damaged cultural assets as 3D. This also composes photos of the past with the current buildings, which can increase people's interest and absorption of the contents, and helps them understand and be aware of Korean traditional culture and cultural heritage effectively. In addition, convergence between IT new technology, Augmented Reality(AR) and humanities through storytelling based implementation of cultural heritage in smart phone is attempted to demonstrate that there is strength in which augmented reality technique exerts infinite creativity based on actual reality world.

• Korean Journal of Heritage: History & Science
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• v.47 no.3
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• pp.146-159
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• 2014

After inspecting ground surface or excavating cultural heritage site, the government can take measures for the preservation of buried cultural heritage based on the related law. It means that the provisions complement the limitation of current cultural heritage management system by extending the scope of cultural heritage to be preserved. But we neither have set any matters about implementing the measures for preservation of the buried cultural heritage, nor manage the heritage and its surroundings after implementing the measures. Due to these insufficiency of the law, there arise several problems in the field. For example, the measures for preservation are not complete, or preserved cultural heritage is damaged due to inappropriate management. We have to resolve the problems in order to accomplish the original purpose of taking measures for preservation of the heritage. First, it is necessary to make sure of the legal status of preserved buried cultural heritage, to establish the standards to decide whether to preserve it or not. We need to have regulations by law or internal rule on the daily management, who should manage it, what and how the manager should manage. It is also important for local residents to take an active part in preserving and utilizing the cultural heritage as the owner. Through building up the foundation mentioned above, the meaning and value of preserved buried cultural heritage can be expanded widely.

• Korean Journal of Remote Sensing
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• v.36 no.6_1
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• pp.1367-1377
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• 2020

The purpose of this study is to assess the seismic vulnerability of buildings in Gyeongju city starting with the earthquake that occurred in the city on September 12, 2016, and produce a seismic vulnerability map. 11 influence factors related to geotechnical, physical, and structural indicators were selected to assess the seismic vulnerability, and these were applied as independent variables. For a dependent variable, location data of the buildings that were actually damaged in the 9.12 Gyeongju Earthquake was used. The assessment model was constructed based on random forest (RF) as a mechanic study method and support vector machine (SVM), and the training and test dataset were randomly selected with a ratio of 70:30. For accuracy verification, the receiver operating characteristic (ROC) curve was used to select an optimum model, and the accuracy of each model appeared to be 1.000 for RF and 0.998 for SVM, respectively. In addition, the prediction accuracy was shown as 0.947 and 0.926 for RF and SVM, respectively. The prediction values of the entire buildings in Gyeongju were derived on the basis of the RF model, and these were graded and used to produce the seismic vulnerability map. As a result of reviewing the distribution of building classes as an administrative unit, Hwangnam, Wolseong, Seondo, and Naenam turned out to be highly vulnerable regions, and Yangbuk, Gangdong, Yangnam, and Gampo turned out to be relatively safer regions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.56-64
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• 2021

Leakage due to deterioration and damage is one of the major causes of volume change by freezing and thawing, and it leads micro-cracking and surface scaling in concrete structures. The deterioration of damaged concrete accelerates with the chloride attack. Thus, in the detailed guidelines for facility performance evaluation (2020), the quality of cover concrete and the freeze-thaw (FT) repetition cycle were newly suggested for concrete durability assessment. The quality of cover concrete should be evaluated by the rebound hammer test and the FT repetition cycle should be also considered in the deterioration environmental assessment. This study suggested the application of fast dynamic based nonlinear ultrasound method to monitor initial micro-scale damage under freezing and thawing environment. Concrete specimens were fabricated with different water-cement ratios (40%, 60%) and air contents (1.5% and 3.0%). The compressive strength, rebound number, relative dynamic modulus, and nonlinear ultrasound were measured with different FT cycles. The scanning electron microscopy was also performed to investigate the micro-scale FT damage. As a result, both the rebound number and the relative dynamic modulus had difficulty to detect early damage but the proposed method showed a potential to detect initial micro-scale damage and predict the FT resistance performance of concrete.