• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05c
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• pp.89-97
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• 2009

As landscaping building roofs and concrete structures increase gradually for low carbon green growth policy of government, But waterproofing membranes of those structures are effecting by root penetration of landscape plant. 80, we progressed study about test method for fast evaluating root resistance of waterproofing materials jointly with Tokyo Institute of Technology. The result of the study is as follows: (1) The penetrating load of the needle at the displacement speed of 1mm/min was measured for various membrane to basis and lap joints of membrane, the load force was $3{\sim}50$ N by material variously. (2) According to the test method of deriving rhizomes of bamboo grass to basis and lap joints of membrane, there were no penetrated membrane until present, but need persistent observation. (3) Test method of deriving rhizomes of bamboo grass to basis and lap joints of membrane can shorten from period of 2 years to 1 year for testing. Because rhizomes of bamboo grass can grow from May to September, test is possible in same period.

• Journal of Korean Association for Spatial Structures
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• v.23 no.1
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• pp.25-34
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• 2023

This paper presents a computational fluid dynamics (CFD) analysis to investiagate the effect of expansion chamber on overpressure reduction in protective tunnels subjected to detonation of high explosives. A commercial CFD code, Viper::Blast, was used to model the blast waves in a protective tunnel with a length of 160 m, width of 8.9 m and height of 7.2 m. Blast scenarios and simulation matrix were establihsed in consideration of the design parameters of expansion chamber, including the chamber lengths of 6.1 m to 12.1 m, widths of 10.7 m to 97 m, length to width ratios of 0.0 to 5.0, heights of 8.0 m and 14.9 m, and ratios of chamber to tunnel width of 1.2 to 10.9 m. A charge weight of TNT of 1000 kg was used. The mesh sizes of the numerical model of the protective tunnel were determined based on a mesh convergence study. A parametric study based on the simulation matrix was performed using the proposed CFD tunnel model and the optimized shape of expansion chamber of the considered tunnel was then proposed based on the numerical results. Design recommendations for the use of expansion chamber in protective tunnel under blast loads to reduce the internal overpressures were finally provided.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.3
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• Journal of the Daesoon Academy of Sciences
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• v.35
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• pp.359-392
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• 2020

In this paper, we examined the development of Chinese Taoist architecture, its cultural implications, and comprehensively summarized the core principles of the Taoist ecological ideas that are reflected in Taoist architecture. This is a groundwork for exploring an ideological model for sustainable ecological architecture in modern cities. Taoist architecture has a long history that has led to changes, developments, and a gradual maturation. Zhi (治), Lu (廬), and Jing (靖), were the first architectural forms of the early Taoist body. These formed the basis for the future development of Taoist Courts (宮觀). The state-sponsored government-run Taoist Courts established from the time of the North and South Dynasties to the time of Tang Dynasty led to a constant standardization of the rites, and these Courts gradually became more and more formalized. Since the establishment of Quanzhenjiao (全眞敎) in the early 12th century, a movement that emphasized putiy training, architecture for the ascetic practice emerged in remote natural spaces suitable for strict ascetic practices. Meanwhile, in Taoist architecture, the type and structure of buildings were strengthened in order to worship various gods. The various Taoist Courts established through this historical process embody the elements, institutions, and ecological ideas of Taoist culture. Taoist architecture basically pursued the idealism of Paradise in a Deep Cave (洞天福地) and adopted a feng-shui theory of using natural terrain artfully in selecting a place and building a layout. This was reflected through their ecology. Meanwhile, Taoist architecture does not destroy the balance of nature by emphasizing the utilization of local natural resources whenever possible while selecting building materials according to the principles of yinyang and the five movements (陰陽五行). In addition, Taoism aims to select simple places for practising asceticism and ancestral rituals whenever possible because of the need to maintain a simple mind, suppress desire, and return to a state of purity. This attitude is an indication of a kind of simple ecological ideas and value of frugality easily found in Taoism. The ecological ideas of Taoism provide abundant resources for considering solutions to the ecological crisis that arises in the creation of residential environments. Through the ecological ideas of Taoism, we can find a direction to understand the relationship between human beings and nature while creating new, sustainable residential environments.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.4
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• pp.79-90
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• 2021

This paper presents a study to reduce the effect of blast pressure on the blast valves installed in protection tunnels, where the shape of the tunnel entrance and the blast pocket is optimized based on the predetermined basic shape of the protective tunnels. The reliability of the numerical tunnel models was examined by performing analyses of mesh convergence and overpressure stability and with comparison to the data in blast-load design charts in UFC 3-340-02 (DoD, 2008). An optimal mesh size and a stabilized distance of overpressure were proposed, and the numerical results were validated based on the UFC data. A parametric study to reduce the blast overpressures in tunnel was conducted using the validated numerical model. Analysis was performed applying 1) the entrance slope of 90, 75, 60, and 45 degrees, 2) two blast pockets with the depth 0.5, 1.0, and 1.5 times the tunnel width, 3) the three types of curved back walls of the blast pockets, and 4) two types of the upper and lower surfaces of the blast pockets to the reference tunnel model. An optimal solution by combining the analysis results of the tunnel entrance shape, the depth of the blast pockets, and the upper and lower parts of the blast pockets was provided in comparison to the reference tunnel model. The blast overpressures using the proposed tunnel shape have been reduced effectively.

• KIEAE Journal
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• v.13 no.1
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• pp.101-108
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• 2013

The purpose of this research was to analyze the correlation of residential satisfaction and the size of housing unit in apartment housing through the case study of 1,619 samples of 36 housing estates. The contents of this research consisted of two main parts. The first part was to identify the differences of residential satisfaction of dwellers, based on the size of housing unit, in apartment housing. The second part was to analyze the characteristics of residential environment, which might have an influence on the differences of residential satisfaction. the findings of this study were that the residential satisfaction of dwellers was proportional to the size of housing unit except $39m^2$ under housing unit, and the size of housing unit was not proportional to the residential satisfaction of outdoor openness exactly, but the size of housing unit was proportional to increase of the distance between building and building, and decrease of the building surface coverage ratio to outdoor area. This research will contribute to the establishment of the site planning methods which increase residential satisfaction in apartment housing, while promoting the quality of residential environment in Korea.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.404-412
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• 2020

Herein, the properties and self-healing performance of cement mortar incorporating calcium sulfoaluminate(CSA), crystalline admixture(CA), and magnesium oxide(MgO) were investigated. Mortar strength test and water permeability experiments were conducted to analyze self-healing performance of the mortar. Also, variation in crack width were measured via digital optical microscope observation. The hydration products formed in the crack via self-healing were analyzed using x-ray diffraction(XRD), thermogravimetry(TG), and digital optical microscope. The analysis revealed that compressive strength and tensile strength increased as CA substitutional ratio increased. However, in the case of MgO replacement, the compressive strength and tensile strength decreased as the CA substitution ratio increased. The products in the recovered cracks are found to be mostly Ca(OH)2, MgCO3, and CaCO3. CaCO3 was shown to be the main healing product and had a higher portion than Ca(OH)2 and MgCO3 in the recovery products. Moreover, the optimal mix derived via water permeability and crack width results was 8% CSA + 1% CA + 2.5% MgO.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.425-430
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• 2016

Both rapid industrial development and society has achieved more comfortable life. But, behind this facts of this industrial development have current pictures that occur global warming and much more by-products by environmental pollution. Therefore, this study used BFS and CFA as by-products to reduce cement usage emitted at a high rate of $CO_2$ gas, to examine sludge recycling strategy more than 200,000ton emitted at local dyeing complex, we suggest basic data research about non-cement matrix properties of utilizing dyeing sludge carbide. As a result, the more dyeing sludge carbide replacement ratio gets higher, the more air content and flow rise. Also, as the dyeing sludge carbide replacement ratio increase more, flexural strength and compressive strength go down.

• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.141-147
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• 2017

The purpose of this study is to develop an inorganic filling adhesive using MKP and borax based on Dead-burn magnesia and fly ash. First, basic experiments was conducted to derive the proper addition rate of MKP. And this experiment was carried out according to addition ratio of borax. The test items are measured for pot life, flexural strength, compressive strength, adhesive strength, tensile strength, ratio of temperature change, ratio of hardening shrinkage, radon gas and formaldehyde emission. As a result, the proper addition rate of phosphate was 35%. The pot time is about 10minutes, 15minutes and 25minutes according to addition rate of borax. The flexural strength and compressive strength were obtained at 12hours for minimum flexural strength of 8.0MPa and minimum compressive strength of 31.0MPa. The tensile strength was the least 4.1MPa, and the ratio of hardening shrinkage was maximum 2.4% and ratio of heat change was maximum - 0.3%, which satisfied all of the quality standards of 'KS F 4923' (epoxy resin for repairing concrete structures). Both Radon gas and formaldehyde emission was not detected.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.3
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• pp.139-145
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• 2011

Objectives: This investigation is purposed to evaluate the airborne asbestos concentrations in the public buildings having asbestos containing materials(ACMs) in Seoul. Methods: The Seoul Metropolitan Government carried out an asbestos survey to the city-owned public buildings to identify the level of risk exposure, classified into low, moderate and high risk. To evaluate the airborne concentration of asbestos, 11 sampling sites in ten buildings based on the survey were selected. The air samples from the eleven sites were analyzed by Phase Contrast Microscopy(PCM) and Transmission Electron Microscopy (TEM), and compared the analytical results from the both. Results: 1. The airborne fiber concentrations by PCM were less than the detection limit($7f/mm^2$) in 9(82%) out of 11 sampling sites. The highest concentration was 0.0043 f/cc, but it was below the guideline value for indoor air quality(0.01 f/cc), proposed by the Ministry of Environment, Korea. 2. In two sampling sites, having moderate risk level, the chrysotile was identified and showed it's concentrations of 0.0102 s/cc and 0.0058 s/cc, less than $5{\mu}m$ lengths. 3. The ACMs identified in the two sampling sites were a packing material(65% of chrysotile) in mechanical area and a thermal system insulation(5% of chrysotile) in a boiler room. Having more possibility of asbestos emission in the mechanical area, it would be required to set up and carry out the asbestos management plan. Conclusions: Based on the result of this study, the airborne asbestos concentrations in the public buildings with ACMs were generally lower than the guideline value for indoor air quality. There are widespread concerns about the possible health risk resulting from the presence of airborne asbestos fibers in the public buildings. Most of the previous studies about airborne asbestos analysis in Korea were performed based on PCM method that asbestos and non-asbestos fibers are counted together. In the public and commercial buildings, having ACMs, it is suggested that the asbestos be analyzed by TEM method to identify asbestos due to concerns about asbestos exposure to workers and unspecified people.