• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.1
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• pp.45-55
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• 2022

Because boundary confinement details proposed in the current design standards are significantly inferior in workability and production quality, it is necessary to develop boundary confinement details of RC structural walls that are capable of ensuring seismic performance and workability. With the recent development of the wire rod manufacturing technology, various pre-fabricated continuous hoop details can be manufactured. In this study, an analysis was conducted on the moment-curvature relationship of RC structural walls to which the pre-fabricated continuous hoop details were applied. According to the nonlinear cross-section analysis, the RC structure wall to which the details of the pre-fabricated continuous hoop details are applied can ensure seismic performance as the area of the pre-fabricated continuous hoop increases. Based on these research results, when applying the pre-fabricated continuous hoop in detail, it is necessary to secure the area of the pre-fabricated continuous hoop as much as the area of the existing boundary confinement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.1
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• pp.64-70
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• 2023

In this study, reliability tests of torsion control expansion anchors according to drill bit diameters were performed. The standard deviation and coefficient of variation of the anchor were reviewed through the tests for each variable, and the results were compared and evaluated with the standard test results. As a result of the reliability test of the M12 and M16 anchors with 1.04 times the drill bit diameter, they were within 20% of the ultimate tensile load permissible standard coefficient of variation. It was found that the pulling-out performance of the anchor installed in the large hole was sufficiently secured. However, it was found to be about 253% and 210% of the design strength, indicating that the pulling performance of the anchor installed in 1.04 times the drill bit diameter was sufficiently secured. As a result of the reliability test of the M12 and M16 anchors with 1.02 times the drill bit diameter, the value of the coefficient of variation of the ultimate tensile load limit was within 20%, which satisfies the test standard. It was shown to be about 136% and 168% of the design strength, indicating that the pulling-out performance of the anchor installed in 1.02 times the drill bit diameter is sufficiently secured.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.47-56
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• 2009

Rock bolts and shotcrete play a crucial role as a main support system in the underground space. Thus, the safety of the underground space may be affected by the defect of rock bolts. In order to evaluate the rock bolt integrity by using non-destructive technique, the transmission method of the guided ultrasonic waves, which are generated by using the piezo disk elements has been successfully performed. The energy generated by the piezo disk elements, however, is not enough for the rock bolts in the field. In addition, the piezo disk elements should be installed at the end of the steel bar during construction of the rock bolts. The purpose of this study is the devolvement of the reflection method, which may generate enough energy, and the application in the field rock bolts. Both laboratory and field tests are carried out. The guided ultrasonic waves with high energy are generated by the hammer impact with the center punch, and the AE sensor is used to measure the reflected guided waves. The received guided waves are analyzed by the wavelet transform. The peak value of the wavelet transform produces the energy velocity, which is used for the evaluation of the rock bolt integrity. The energy velocity increases with an increase in the defect ratio in both laboratory and field rock bolts. This study demonstrates that the hammer-impact reflection method may be a suitable method for the evaluation of the rock bolt in the field.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.82-93
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• 2024

Since the cement industry generates more than 60 % of CO₂ during the clinker production process, supplementary cementitious materials are used worldwide to reduce CO₂ efficiently. Mainly used supplementary cementitious materials such as blast furnace slag and fly ash, which are used in various industries including the cement industry, concrete admixtures, and ground solidification materials. However, since their availability is expected to decrease in the future according to the carbon neutrality strategy of each industry, new supplementary cementitious materials should be used to achieve the cement industry's goal for increasing the additive content of Portland cement. Limestone is a material that already has a large amount in the cement industry and has the advantage of high grinding efficiency, so overseas developed countries established Portland limestone cement standards and succeeded in commercialization. This study was an experimental study conducted to evaluate the possibility of utilizing domestic PLC, the effect of fineness and replacement ratio on the physical properties of cement was investigated, and the environmental impact of cement was evaluated by analyzing CO₂ emissions.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.63-71
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• 2024

Through the development of construction technology, various construction projects such as redevelopment projects, undergrounding of roads, expansion of subways, and metro railways are being carried out. However, this has led to an increase in the number of construction projects in existing urban centers and neighborhoods, resulting in an increase in the number of damages and disputes between neighboring buildings and residents, as well as an increase in safety accidents due to the aging of existing buildings. In this study, digital data was applied to a graphics program to objectify the progress of cracks by comparing the creation of cracks and the increase in length and width through photographic images and presenting the degree of cracks numerically. Through the application of the program, the error caused by the subjective judgment of crack change, which was mentioned as a shortcoming of the existing field survey, was solved. It is expected that the program can be used universally in the building diagnosis process by improving its reliability if supplemented and improved in the process of use. As a follow-up study, it is necessary to apply the extraction algorithm of the digital graphic data program to calculate the length and width of the crack by itself without human intervention in the preprocessing work and to check the overall change of the building.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.4
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• pp.303-314
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• 2024

Recently, the consecutive shield tunnel boring machine (TBM) has gained attention for its potential to enhance TBM penetration rates. However, its development requires a thorough risk assessment due to the unconventional nature of its equipment and hydraulic systems, coupled with the absence of design or construction precedents. This study investigated the causal relationships between four accidents and eight relevant sources associated with the consecutive shield TBM. Subsequently, risk levels were determined based on expert surveys and a risk matrix technique. The findings highlighted significant impacts associated with collapses or surface settlements and the likelihood of causal combinations leading to misalignment. Specifically, this study emphasized the importance of proactive mitigation measures to address collapses or surface settlements caused by inadequate continuous tail void backfill or damaged thrust jacks. Furthermore, it is recommended to develop advanced non-destructive testing technology capable of comprehensive range detection across helical segments, to design a sequential thrust jack propulsion system, and to determine an optimal pedestal angle.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.1
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• pp.129-139
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• 2019

Mapping urban areas using the earth observation satellites is useful for monitoring urban expansions and measuring urban developments. In this research, the different thresholds for detecting the urban areas separately from the remote-sensing index images (normalized-difference built-up index(NDBI) and urban index(UI) images) generated from the Landsat-8 image acquired in Daegu, South Korea were evaluated through the following steps: (1) the NDBI and UI images were separately generated from the given Landsat-8 image; (2) the different thresholds (-0.4, -0.2, and 0) for detecting the urban areas separately from the NDBI and UI images were evaluated; and (3) the accuracy of each detected urban area was assessed. The experiment results showed that the threshold -0.2 had the best performance for detecting the urban areas from the NDBI image, while the threshold -0.4 had the best performance for detecting the urban areas from the UI image. Some misclassification errors, however, occurred in the areas where the bare soil areas were classified into urban areas or where the high-rise apartments were classified into other areas. In the future research, a robust methodology for detecting urban areas, including the various types of urban features, with less misclassification errors will be proposed using the satellite images. In addition, research on analyzing the pattern of urban expansion will be carried out using the urban areas detected from the multi-temporal satellite images.

• Korean Journal of Heritage: History & Science
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• v.46 no.1
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• pp.140-159
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• 2013

The wooden stupa of Hwangyongsa temple - which was designed and constructed by master craftsman Abigi of the Baekje Dynasty during the Silla Dynasty between the 12th year of Queen Seondeok (AD 643) and AD 646 - can be regarded as a typical Korean wooden stupa. However, it was destroyed by fire during an invasion by the Mongolians in AD 1238 during the Koryo Dynasty. In spite of progress in research for the restoration of the wooden stupa, there are some remains to be re-considered in regard to ruins, relics and literature previously discovered. In particular, research conducted on frame construction and structure can be considered an important basis for restoration. However, previous studies seem to have not attempted to establish structural and formative characteristics of the wooden stupa based on the indigenous techniques and styles of traditional Korea, but general characteristics of the wooden stupa biased toward cultural interchange with neighbouring countries. As such, in this study the frame construction and structure of the wooden stupa of Hwangyongsa temple were analysed and considered in detail based on the re-interpretation of literature which can be a clue about the structure of the stupa, related ruins of the 7th century period, and previous studies. As a result, this paper supposed and presented a model picture for the plane arrangement of pillars, structural methods for Dwibburi (뒤뿌리) of Haangjae (하앙재), Shimju (심주), and other key areas. The author hopes that this study contributes substantially to research on the wooden stupa of ancient Korea and to the establishment of construction and structural methods.

• 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 Architectural Institute of Korea Planning & Design
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• v.34 no.9
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• pp.55-66
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• 2018

This study aims to propose color affective model of indoor space by evaluating subjects' physiological responses according to the types of behavioral and affective system. 99 subjects(44 females, 55 males) in their 20s, who had no disorders in visual perception, participated in the experiment. To categorize the subjects based on behavioral and affective system, BAS/BIS scale and Affective scale were used. Color stimuli were composed of five basic colors and three tones: vivid, pale and dull tone of R, Y, G, B, P. For physiological experiment, right and left prefrontal alpha activity was measured to analyze prefrontal EEG asymmetry. Participants were exposed to fifteen color stimuli for 20 seconds each other under the positive and negative emotional condition in a research room with the natural light blocked. The results and conclusion of this study are as follows. Along with factors of behavioral and affective system, cluster analysis was carried out and four types were classified. Type A had high BAS sensitivity, especially high 'drive' trait, and showed high levels of 'anxiety' and 'anger'. Type B had low BAS sensitivity, especially low 'fun seeking' and low 'drive' trait, and showed low levels of 'anxiety' as well as low levels of 'happiness'. Type C had low BIS sensitivity and showed high levels of 'happiness' and low levels of 'sadness'. Type D had high BIS sensitivity and showed high levels of 'lethargy' and 'sadness'. As a result of EEG signal analysis of color stimuli, Type B, Type C, and Type D showed significant differences in prefrontal alpha asymmetry under the negative emotional stimuli. Type B showed more left prefrontal activation in the spaces with pale R and dull G. Type C showed more left prefrontal activation in the spaces with vivid Y and B, pale R, and dull R, G, P. Type D showed more left prefrontal activation in the spaces with vivid Y and P, pale R, Y, P, and dull R, Y, G, B, P. The group of high BAS sensitivity was not influenced by color stimuli under the emotional conditions, whereas the group of high BIS sensitivity was affected by color stimuli under the negative emotional conditions. They showed left prefrontal activation when they were exposed the spaces with vivid, pale, dull tones of Y and P wall.