• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.42 no.12
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• pp.72-78
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• 2013

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.403-409
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• 2017

In this study, mix proportioning of porous concrete with compressive strength and porosity exceeding 3MPa and 30%, respectively, was examined and then load capacity and flexural toughness of the porous concrete block were evaluated according to the different arrangements of the GFRP bars. To achieve the designed requirements of porous concrete, it can be recommended that water-to-cement ratio and cement-to-coarse aggregate ratio are 25% and 20%, respectively, under the aggregate particle distribution of 15~20mm. The failure mode of porous concrete blocks reinforced with GFRP bars was governed by shear cracks. As a result, very few flexural resistance of the GFRP was expected. However, the enhanced shear strength of porous concrete due to the dowel action of the GFRP bars increased the load capacity and toughness of the blocks. The porous concrete blocks reinforced with one GFRP bar at each compressive and tensile regions had 2.1 times higher load capacity than the companion non-reinforced block and exhibited a high ductile behavior with the ultimate toughness index ($I_{30}$) of 43.4.

• Korean Journal of Construction Engineering and Management
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• v.23 no.1
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• pp.113-117
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• 2022

Additive manufacturing (AM, also known as 3D printing) technology is digitalized technology, making it easy to predict and manage quality and also, have design freedom ability. With these advantages, AM technology is applied to various industries. In particular, a method of manufacturing buildings and infrastructure with AM technology is being proposed to the construction industry. However, the application of AM technology is restricted due to problems such as insufficient history and quality of technology, lack of construction management methods, and certification of manufacturing products. Therefore, the manufacture of architectural products is implemented with indirect AM technology. In particular, it manufactures formwork using AM and injecting building materials to implement the architectural product. In this study, hybrid type material extrusion AM is used to manufacture large-sized formwork and implement building products. Moreover, we identify factors that can predict productivity and economic feasibility in the additive manufacturing process. As a result, design optimization results are proposed to reduce the production cost and time of architecture buildings.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.367-368
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• 2009

High-rise building in modern society is becoming increasingly necessary to reduce the weight of the building. Accordingly, increased use of lightweight bubble concrete is a trend Porous ceramics (ALC) is the most common, lightweight bubble concrete. And it is by lightweight blocks the same used as building materials. This research is related to the physical characteristics of ALC controlled by particle size and contents of raw materials.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.39-45
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• 2018

Research on FA(Fly ash) is actively carried out, while the research on BA(Bottom ash) is not so, and research on BA recycling field is urgently required. Therefore, in this study, we investigated the lightweight and thermal insulation characteristics of BA mortar by comparing BA mortar made with porous dry BA(air-cooled) and general mortar. To investigate the lightweight of BA, density test, unit volume mass test and SEM(Scanning Electron Microscope) test were performed. BA mortar and general mortar molds were prepared for the thermal insulation test at room temperature and humidity environment determined by KS A 0006 and they were dried at the temperature of $105{\pm}2^{\circ}C$ until the weight became constant. As a result of the lightweight test, the lightweight of BA mortar is about 30% lighter than the general mortar. Therefore, BA is expected to contribute to reduce the building load when used as building material. As a result of thermal insulation test, the thermal conductivity of BA mortar is about 30% better than that of general mortar.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.363-370
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• 2016

Lightweight geopolymers are more readily produced and give higher fire resistant performance than foam cement concrete. Lowering the density of solid geopolymers can be achieved by inducing chemical reactions that entrain gases to foam the geopolymer structure. This paper reports on the effects of adding different concentrations of aluminum powder on the properties of cellular structured geopolymers. The apparent density of lightweight geopolymers has a range from 0.7 to $1.2g/m^3$ with 0.025, 0.05 and 0.10 wt% of a foaming agent concentration, which corresponds to about 37~60 % of the apparent density, $1.96g/cm^3$, of solid geopolymers. The compressive strength of cellular structured geopolymers decreased to 6~18 % of the compressive strength, 45 MPa of solid geopolymers. The microstructure of geopolymers gel was equivalent for both solid and cellular structured geopolymers. The workability of geopolymers with polyprophylene fibers needs to be improved as in fiber-reinforced cement concrete. The lightweight geopolymers could be used as indoor wall tile or board due to fire resistance and incombustibility of geopolymers.

• Journal of the Korean Geosynthetics Society
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• v.22 no.4
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• pp.51-61
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• 2023

In this study, in order to improve the fire resistance performance of structures in case of fire in buildings and structures, PVA fibers and the ZnO particles combined with mesoporous nano silica (MSNs) were mixed with cement mortar, and the specimen was exposed to a temperature range of 20~1100℃. Then the residual compressive strength and weight change rate were measured to determine whether the fire resistance performance changed. As a result of the study, it was found that mixing mesoporous nano silica and PVA fiber together did not contribute to improving the fire resistance performance of cement mortar. On the other hand, mixing 0.5% of mesoporous nano silica and 0.1 vol% of PVA fiber showed the best improvement test results, showing that it was advantageous for fire resistance performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.24-31
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• 2021

The soundproof tunnels have been generally designed with H-beam girders, and the high weight of H-beam may cause the excessive design of the substructure. To solve this problem, this paper proposes a new soundproof tunnel girder design composed of pipes and discontinuous plates. First, the structural behavior of the straight girder according to the design parameters was examined through finite element analysis. The arrangement and shape of the plates were determined as the design parameter, to obtain the optimal design of girder. After then, the structural behavior and buckling stability of the arched girder were subsequently evaluated. As a result of the parameter analysis, it was confirmed that the axial force acting on the girder increased and the moment decreased as the ratio of unsupported sections decreased or the number of supporting plates increased. The stress concentration on the pipe member was relieved by increasing the long axis length of the elliptical plate. Arched girder analysis showed that the structural efficiency increase as the long axis of elliptical plate increase. As a result of the buckling evaluation, the buckling threshold load of the three connected girders was about 3.7 times higher than the design load. Consequently, it was confirmed that the proposed soundproof tunnel structure design satisfies both light weight and structural safety.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1153-1160
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• 2004

In contemporary society, vibration and noise in the road nearby buildings have become social problems as vehicles operation has increased. Especially. in the case of the building used to art performance, available suitability of the building is tested by the indoor noise class. Therefore, the Purpose of this paper is the measurement of the structure-borne noise of Seoul Art Center nearby Umyeonsan tunnel and analyzing the effects of countermeasure to it. To measure the effects of countermeasure, not only structure-borne noise is measured, but also the vibration is measured, before and after the construction of Pavement using pad and porous asphalt. Consequently, the sound pressure level in art center 1st floor is reduced after mat pavement method, structure-borne noise that was high In 25Hz wide-band before pavement decreased regardless of experimental vehicle's velocity Using porous asphalt pavement the noise was reduced about 3 dB(A).

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.537-544
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• 2020

The interfacial transition zone(ITZ) which is the boundary layer between cement composites and aggregates is considered to be the region of gradual transition, heterogeneous, and the weakest part of concrete. For the development of lightweight high strength concrete, it is essential to evaluate the mechanical properties of ITZ between high strength concrete with low water-binder ratio and lightweight aggregates. However, the mechanical properties of ITZ are not well established due to its high porosity and complex structure. Furthermore, the properties of ITZ in concrete using lightweight aggregates are dominated by more various variations (e.g. water-binder ratio, water absorption capacity of aggregate, curing conditions) than normal-weight aggregate concrete. This study aims to elucidate the mechanical properties of ITZ in lightweight high-strength cement composites according to the types of aggregates and the aggregate sizes. Nanoindentation analysis was used to evaluate the elastic modulus of ITZ between high strength cement composites with the water-binder ratio of 0.2 and normal sand, lightweight aggregate with different aggregate siz es of 2mm and 5mm in this study.