• Journal of the Korea Institute of Building Construction
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• v.14 no.2
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• pp.118-126
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• 2014

The establishment of the technology for evaluating friction resistance and pipe pressure and the relation of the fluid characteristics and pumpability of concrete is essential for concrete pumping performance for the rapid construction of super-tall buildings. In this study, a quantitative evaluation of concrete fluid characteristics and surface friction resistance was performed, applying different concrete mix proportions and pumping conditions. To achieve this, we developed a temporary horizontal pumping evaluation system to measure pipe pressure and surface friction characteristics, and performed an experiment to investigate the relations between concrete rheology characteristics and friction resistance in pipe. The experiment found that in terms of the rheology characteristics, plastic viscosity was reduced remarkably after pumping. As well, high regression between the surface friction and pressure gradient was confirmed. This means that it is possible to evaluate the friction resistance between concrete and pipe by means of a pumping system that includes a frictional resistance testing pipe. In addition, high regression between the plastic viscosity of concrete after pumping and friction resistance coefficient was confirmed. Finally, it is considered that pumping pressure can be predicted using the friction resistance coefficient derived in this study, and it has high regression.

• International Journal of High-Rise Buildings
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• v.10 no.4
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• pp.335-344
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• 2021

In structural engineering practice, understanding the performance of composite columns under extreme loading conditions such as high-rise bulding, long span and heavy loads is essential to accuratly predicting of material responses under severe loads such as fires or earthquakes. Hitherto, the combined effect of partial axial loads and subsequent elevated temperatures on the performance of hollow steel column filled fly ash concrete have not been widely investigated. Comprehensive test was carried out to investigate the effect of elevated temperatures on partial axially loaded square hollow steel column filled fly ash concrete as reported in this paper. Four batches of hollow steel column filled fly ash concrete ( 30 percent replacement of fly ash), (HySC) and normal concrete (CFHS) were subjected to four different load levels, n_f of 20%, 30%, 40% and 50% based on ultimate column strength. Subsequently, all batches of the partially damage composite columns were exposed to transient elevated temperature up to 250℃, 450℃ and 650℃ for one hour. The overall stress - strain relationship for both types of composited columns with different concrete fillers were presented for each different partial load levels and elevated temperature exposure. Results show that CFHS column has better performance than HySC at ambient temperature with 1.03 relative difference. However, the residual ultimate compressive strength of HySC subjected to partial axial load and elevated temperature exposure present an improvement compared to CFHS column with percentage difference in range 1.9% to 18.3%. Most of HySC and CFHS column specimens failed due to local buckling at the top and middle section of the column caused by concrete crushing. The columns failed due to global buckling after prolong compression load. After the compression load was lengthened, the columns were found to fail due to global buckling except for HySC02.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.2
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• pp.30-47
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• 2022

This study analyzed the characteristics of cold air flow according to spatial types in urban areas of Changwon-si, Gyeongsangnam-do. The spatial types were classified by cluster analysis considering the land use map, building information, and topographic characteristics produced on the Changwon biotope map. The amount of cold air and wind speed were derived by KLAM_21 modeling. As a result, spatial types were classified into a total of 14 types considering the density and height of buildings, land use types, and topographic characteristics. Cold air flow was found to generate cold air in the valley of the forest area outside urban area, move through roads and open spaces, and accumulate in the low-lying national industrial complex, and then spread cold air throughout the urban areas. There was a lot of cold air flow in the tall building area, and the cold air accumulation was less in the slope and ridge areas. The results of this study were able to understand the characteristics of cold air flow according to building density, land use type, and topography, which will be usefully used as basic data for urban wind road construction to mitigate climate and improve air quality in urban areas.

• Journal of Navigation and Port Research
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• v.47 no.1
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• pp.18-24
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• 2023

After the Great East Japan Earthquake, many reports and books that compiled testimonies of adult victims were published. Thus, refugee situations are well known, but information on the refugee situations of Japanese students is not. This is because what actions the students took and how they sought refuge from an earthquake or tsunami have not been fully recognized. The purpose of this study was to examine and analyze students' refuge behavior in the Great East Japan Earthquake and to predict the refuge behavior of students affected by future disasters. The results of the study showed that students passively acquired information about earthquakes and tsunamis and that their refuge behavior was highly dependent on adults. Immediately after an earthquake, people tended to protect themselves and stay in place until the shaking stopped. However, they tended to move to another place after the shaking occurred frequently. Students living on ria coastlines were likely to move to high places to escape the threat of earthquakes and tsunamis, whereas students living in plain regions were likely to move vertically to tall buildings, such as schools. As for the mode of movement to refugee shelters, the students arrived at the final refugee shelters in one move, and it is assumed that the refugee shelters should be decided in advance and the students should move there.

• International Journal of High-Rise Buildings
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• v.12 no.3
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• pp.225-234
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• 2023

Even at this point in the era of digital transformation, we are still facing many problems in the safety sector that cannot prevent the occurrence or spread of human casualties. When you are in an unexpected emergency, it is often difficult to respond only with human physical ability. Human casualties continue to occur at construction sites, manufacturing plants, and multi-use facilities used by many people in everyday life. If you encounter a situation where normal judgment is impossible in the event of an emergency at a life site where there are still many safety blind spots, it is difficult to cope with the existing manual guidance method. New variable guidance technology, which combines artificial intelligence and digital twin, can make it possible to prevent casualties by processing large amounts of data needed to derive appropriate countermeasures in real time beyond identifying what safety accidents occurred in unexpected crisis situations. When a simple control method that divides and monitors several CCTVs is digitally converted and combined with artificial intelligence and 3D digital twin control technology, intelligence augmentation (IA) effect can be achieved that strengthens the safety decision-making ability required in real time. With the enforcement of the Serious Disaster Enterprise Punishment Act, the importance of distributing a smart location guidance system that urgently solves the decision-making delay that occurs in safety accidents at various industrial sites and strengthens the real-time decision-making ability of field workers and managers is highlighted. The smart location guidance system that combines artificial intelligence and digital twin consists of AIoT HW equipment, wireless communication NW equipment, and intelligent SW platform. The intelligent SW platform consists of Builder that supports digital twin modeling, Watch that meets real-time control based on synchronization between real objects and digital twin models, and Simulator that supports the development and verification of various safety management scenarios using intelligent agents. The smart location guidance system provides on-site monitoring using IoT equipment, CCTV-linked intelligent image analysis, intelligent operating procedures that support workflow modeling to immediately reflect the needs of the site, situational location guidance, and digital twin virtual fencing access control technology. This paper examines the limitations of traditional fixed passive guidance methods, analyzes global technology development trends to overcome them, identifies the digital transformation properties required to switch to intelligent variable smart location guidance methods, explains the characteristics and components of AI-based public facility smart fire safety integrated system (ISFS).

• Korean Journal of Heritage: History & Science
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• v.54 no.3
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• pp.24-51
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• 2021

Since June 2006, there have been active efforts to systematize the permission system including the amendment of [Cultural Heritage Protection Act]. Cultural Heritage Administration prepared standards on reviewing each type of cultural heritages(CH) in 2015, promoted a project on the modification of permission standards and showed remarkable performances in quantitative aspects. But as there has been little change for the cases applied for permission, additional studies on policy are required to improve the management efficiency and reduce the citizens'inconvenience. In response, this study aims to identify the actual management status on the current state alteration permission system, and establish practically utilizable reference materials at permission review. While historic sites(HS) constitute a relatively small proportion in state-designated CHs, they are subject to the designation of permission standards. Also, with their location in the downtown area, the application rate is high (51.4%) and the results are commonly utilizable to other types of CH. We constructed a DB based on the minutes of Cultural Heritage Committee(CHC) on HS and categorized similar features in permission handling results. The result of the analysis is as follows. Out of a total of 5,243 cases for permission applied for HS, 1,734 cases of cultural heritage areas(CHA) and 3,509 cases of historic and cultural environment preservation areas(HCEPA) have been applied. CHA has a great proportion of the applications for events and festivals, which are highly related to CHs or representing the local area. There is a high permission rate on applications for the purpose of public service by local governments. Meanwhile, HCEPA has a high proportion of applying for the installation and extension of buildings and facilities at the private level. Thus, negative decisions were made for tall buildings, massed facilities, or suspected scattering of similar acts. Our actual condition analysis has identified a total of 78 types of harmful acts which may influence the preservation of CHs. 31 types in CHA and 37 types in HCEPA are categorized. Especially, 10 common types of permission have been confirmed in both sectors. As a result, it is expected to secure consistency in the permission administration, enhance the management efficiency and improve the public's satisfaction over the regulatory administration by providing practically utilizable reference materials for altering the current state of CH and for decision making on the part of CHC.

• Korean Journal of Heritage: History & Science
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• v.42 no.2
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• pp.62-85
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• 2009

The Nam-Hae Sin-sa, the South Sea shrine in Yeong-Am, Korea was a national institution for public peace and bliss, was excavated in 2000, and the shrine and the 3-way-gate were reconstructed in 2001. Hae Sin-sa, the Sea shrine is a place for religious service separated into the Nam-Hae Sin-sa, the Dong-Hae Myo, and the Seo-Hae Dan. The Dong-Hae Myo was reconstructed, but restored shrine and 3-way-gate of the Nam-Hae Sin-sa is not perfect in comparison with excavation plan in 2000, therefore new reconstruction was researched through the related literature, the analysis of historical maps and excavation results, the interview with the concerned people and the case study. This research defines the analysis of the Plan of the Nam-Hae Sin-sa Reconstruction as follows. 1. The Nam-Hae Sin-sa was the institution for religious service operated by national direct management, represents the shrine for public peace and bliss on the Mountain, the Sea, and the River. Especially the Nam-Hae Sin-sa had an important position on the pivot of international trade with China and Japan, and had a role of main shrine with another one in the Mt. Ji-ri San. 2. The name of the Sea shrine was called as Nam-Hae Sin-sa(the South Sea shrine), Dong-Hae Myo(the East Sea shrine), Seo-Hae Dan(the West Sea shrine). But the name of the South Sea shrine had changed in the early period of Chosun as Nam-Hae Sin-sa to the later Chosun as Nam-Hae Dang through the research of related literature and historical map. Such as the Seo-Hae Dan, it was constructed for the Dan, the flat raised-floor without buildings, and changed to the type of Sa-Dang with addition of buildings. 3. The historical map of Hae Sin-sa informs the types of the roof, the Mat-bae roof was used in the Dong-Hae Myo, but the Pal-jak roof was showed in the Seo-Hae Dan and the Nam-Hae Sin-sa. 4. According to the analysis of Yong-Ch'uck the unit length, Nam-Hae Sin-sa was reconstructed in the period of Koryo on large scale, but it was restored in the Chosun on middle scale. And the Unit of Yong Ch'uck was changed into Yeong-jo Ch'uck in the period of Chosun. 5. As the results, The Plan of the Nam-Hae Sin-sa Reconstruction designed the new shrine into the 3 Kan front and the 2 Kan side with 3:2 scale. An-ch'o-gong with Yong-du and Yong Mi the ornaments represents head and tail of dragon, the Un-gong and the ornament of Pa-ryun-dae-gong in the building, and the Ch'ung-ryang of the Yong-du show the image of the institution for religious service for the god of the sea who look like dragon. The inner gate building and the main entrance were designed as same plan and scale as Hyang-gyo, the Korean Traditional School and Shrine of Confucianism, on the basis of results of excavation. Raise the 3-tall gate of the main entrance with harmony of the scale and the shape, because the side of gate building has the Mat-bae roof. 6. This research shows that Plan of the Nam-Hae Sin-sa Reconstruction is composed into shrine space and reservation space from the main entrance to inner gate and shrine like Jung-ak Dan in the Mt. Gye-ryong San, and it also informs the well in the west side of Sin-sa is an important factor of the plan of shrine architecture.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.515-525
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• 2007

In this investigation, results of laboratory tests on four reinforced concrete flat plate interior connections with elongated rectangular column support which has been used widely in tall residential buildings are presented. The purpose of this study is to evaluate an effect of column aspect ratio (${\beta}_c={c_1}/{c_2}$=side length ratio of column section in the direction of lateral loading $(c_1)$ to the direction of perpendicular to $c_1$) on the hysteretic behavior under earthquake type loading. The aspect ratio of column section was taken as $0.5{\sim}3\;(c_1/c_2=1/2,\;1/1,\;2/1,\;3/1)$ and the column perimeter was held constant at 1200mm in order to achieve nominal vertical shear strength $(V_c)$ uniformly. Other design parameters such as flexural reinforcement ratio $(\rho)$ of the slab and concrete strength$(f_{ck})$ was kept constant as ${\rho}=1.0%$ and $f_{ck}=40MPa$, respectively. Gravity shear load $(V_g)$ was applied by 30 percent of nominal vertical shear strength $(0.3V_o)$ of the specimen. Experimental observations on punching failure pattern, peak lateral-load and story drift ratio at punching failure, stiffness degradation and energy dissipation in the hysteresis loop, and steel and concrete strain distributions near the column support were examined and discussed in accordance with different column aspect ratio. Eccentric shear stress model of ACI 318-05 was evaluated with experimental results. A fraction of transferring moment by shear and flexure in the design code was analyzed based on the test results.