• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.265-272
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• 2011

Even though concrete is the most important material for building structures, its intrinsic gray color degrades urban esthetics. In order to improve this problem, coloring methods of mixing pigment in concrete batch and painting the surface of concrete surface have been tried. However, applications of the coloring methods in construction field are difficult due to high cost and low durability. Recently, acid stain agent is emerging as a new coloring method for concrete. It is able to apply a remarkably thin colored layer on a concrete surface from chemical reaction between acid and alkaline solutions. This study has examined the changes and variations of the surface layer of mortar specimen from chemical reaction of acid stained agents. The colors were changed into natural irregular stains according to aging. After the staining, no shape change was found from visible inspections. Microstructure of the colored surface applied with acid stained agent was much rougher than that of original mortar. When the colored layer was compared to original surface, crystals of hydrate such as $Ca(OH)_2$ and C-S-H gel were observed. Surface hardness was same or slightly higher in the colored layer. The value of pH was reduced by approximately 10%, weight contents of elements such as Ca, Si, and Al were low. In the chemical composition of the colored layer, the non-cement based elements of Mn, Cr, and Cu increased. Also, Fe and alkali elements of K and Na increased.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.431-438
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• 2016

Recently, Both rapid economic growth and high-quality native finishing materials demand in buildings such as local infrastructure facilities and cultural facilities have increased along with local quarries. So, increasing local quarries and environmental pollution occurred in quarries get the eyes to damaged area of the surroundings. As an example, carcinogen such as solid formed to fixing asbestos and dust have damaged to local resident. Especially, Radon gas released from asbestos can exist everywhere on earth, released soil and rock as radioactive substances, can be caused lung cancer followed by a smoking. When pollution source to indoor air quality that lacking ventilation rate of the residential building moved in a cycle, human responses such as headache, dizziness, etc. get appear, so on it threatened resident's physical condition. Thus, we need to urgent attention to reduction harmful substance. In the case of radon gas of the pollution source to indoor air quality in housing, it has characteristic that keep on going through half-life released from source, we need to control radon gas source than source removal. We set on vermiculite addition ratio to 10% which has harmful substances adsorption performance, proceed experiment to basalt waste rock addition ratio 50, 60, 70, 80(%). The result of an experiment, based on 'KS F 4035, precast terrazzo', we can be obtainable in the best terrazzo at basalt waste rock addition ratio 70%.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.853-856
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• 2008

Lightweight foamed concretes are mainly used in apartment building construction for building room floor insulation, sound proof and height difference adjustment, etc. However, existing lightweight foamed concretes have problems like volume reduction by foam removal and excessive crack occurrence, etc, and for compensation, they developed improved concrete binders for lightweight foamed concrete with special characteristics by adding admixture materials used in concrete manufacturing. Therefore, this study reviewed the possibility of its practical use by analyzing all the engineering characteristics after producing imitation member proposed as actual binders and piling lightweight foamed concrete as improved lightweight foamed concrete binder through prior study, the results are as follows. Plain in which various pulverulent materials are mixed showed about 230mm of flow value, satisfying the target flow value, and at 100mm member, about 4mm of settlement occurred, showing a settlement depth reduction effect double the OPC. On strength, OPC showed highest value, but the three levels all showed strengths above the specified value of KS standard 0.5 grade. From the analysis of drying shrinkage member crack, plain, about 0.1mm, was shown very excellent against drying shrinkage crack.

• Korean Journal of Construction Engineering and Management
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• v.7 no.5
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• pp.128-137
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• 2006

This paper is to develop curtain wall process life-cycle system in high-rise buildings in order to establish effective cooperation communication channels among the diverse constituents. This paper is to provide a base toward a curtain wall life-cycle management system to support decision making and the effective flow in light of information and materials. The four objectives of the research are 1) the analysis of the current curtain wall life-cycle process, 2) the analysis and development of the curtain wall design process As-Is model, and 3) the Muda analysis of the design process As-Is model and the suggestion of the improvements, 4) the development of curtain wall design To-Be model and comparative analysis of the improvement in terms of value streams. This research indicates the wastes decrease (or the values increase) from 6.7% up to 100% in different decision criteria through the improvement by the comparative analysis between the As-ls and To-Be curtain wall design process. This research suggests the potential improvement by VSM and a curtain wall life-cycle management system in curtain wall construction for diverse constituents be significant.

• Elastomers and Composites
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• v.44 no.3
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• pp.282-289
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• 2009

The pressure-sensitive adhesive(PSA) tapes are widely used as floor-sealing material in Korean constructive industry. However, the general PSA tapes can not seal the apertures completely. This is one of main reasons to cause imperfect finishing. In order to solve the problems, the asphalts were modified by FKM powder and SBS in this study. The physical properties of modified asphalts were examined by measuring the softening point, viscosity, tensile strength and adhesion strength of FKM and SBS modified asphalt. The softening point of SBS modified asphalt was increased greatly due to the formation of network structure in asphalt. Also, the change of adhesion strength of SBS modified asphalt with temperature was not so great comparing to those of pure asphalt and FKM modified asphalt. The best results of pressure-sensitive adhesion could be obtained by the SBS(linear) modified asphalt containing 6 wt.% of linear type SBS.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.57-64
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• 2006

Seismic design codes are mainly based on the research results for the inelastic response of structures in high seismicity regions. Since wind loads and gravity loads may govern the design in low seismicity regions in many cases, structures subjected to design seismic loads will have larger overstrength compared to those of high seismicity regions. Therefore, it is necessary to verify if the response modification factor based on high seismicity would be adequate for the design of structures in low seismicity regions. In this study, the adequacy of the response modification factor was verified based on the ductility and overstrength of building structures estimated from the result of nonlinear static analysis. Framed structures are designed for the seismic zones 1, 2A, 4 in UBC-97 representing the low, moderated and high seismicity regions and the overstrength factors and ductility demands of the example structures are investigated. When the same response modification factor was used in the design, inelastic response of structures in low seismicity regions turned out to be much smaller than that in high seismicity regions because of the larger overstrength of structures in low seismicity regions. Demands of plastic rotation in connections and ductility in members were much lower in the low seismicity regions compared to those of the high seismicity regions when the structures are designed with the same response modification factor.

• Journal of Life Science
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• v.16 no.7 s.80
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• pp.1158-1163
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• 2006

Bisphenol A (BPA), 2,2-bis(4-hydroxyphenyl) propane, has been widely used as a monomer for production of epoxy resins and polycarbonate plastics, and final products of BPA include adhesives, protective coatings, paints, optical lens, building materials, compact disks and other electrical parts. Since BPA is a toxic chemical to elicit acute cell cytotoxicity and chronic endocrine disrupting activity, the degradation of BPA has been focused during last decades. To overcome the problem of photo-, and chemical-degradation of BPA, in this study, a bacterium that is able to biodegrade BPA, was isolated. The bacterium, isolated froln the soil of plastic factory, was identified as Acinetobacter calcoaceticus (strain BP-2) based on physiological and 16S rDNA sequencing analysis. A. calcoaceticus BP-2 was able to grow in the presence of $1140{\mu}g\;ml^{-1}$ BPA. Biodegradation experiments showed that BP-2 mineralized BPA via 4-hydroxybenzoic acid and 4-hydroxyacetophenone, and average degradation rate was $53.3{\mu}g\;ml^{-1}\;day^{-1}$ under optimal conditions (pH 7 and $30^{\circ}C$). In high density resting cell $(3.5g-dcw.1^{-1})$ experiments, the maximal degradation rate was increased to $89.7{\mu}g\;ml^{-1}\;h^{-1}$. Our results suggest that BP-2 has high potential as a catalyst for practical BPA bioremediation.

• Korean Journal of Construction Engineering and Management
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• v.1 no.1 s.1
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• pp.87-94
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• 2000

Crack sealing, a routine and necessary part of pavement maintenance, is a dangerous, costly, and labor-intensive operation. Within the North America, about ${\$}200$ million is spent annually on crack sealing, with the Texas Department of Transportation (TxDOT) spending about ${\$}7$ million annually (labor alone accounts for over 50 percent of these costs). Prompted by concerns of safety and cost, the University of Texas at Austin, in cooperation with TxDOT and the Federal Highway Administration (FHWA) has developed a unique computer-guided Automated Road Maintenance Machine (ARMM) for pavement crack sealing. In 1999, successful field tests have been undertaken in 8 States around the U.S. This paper first describes significance of the automated crack sealing and technical advances in automated crack sealers including the ARMM, developed in the U.S. It then discusses the ARMM's field implementation and performance evaluation results, and improvements and modifications suggested through the technology evaluation during the field trials. Current research efforts and future work plans in its further development are also presented in this paper.

• Korean Journal of Construction Engineering and Management
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• v.19 no.3
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• pp.11-22
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• 2018

Existing efforts to reduce total egress time actually focused on reducing travel time. However, consideration to reduce perception time or response time was insufficient although the ratio of travel time is one-third of total egress time and situations which the safety cannot be ensured by only reducing travel time were aroused. Therefore, the concept of disaster information, which could reduce both perception time and response time got attention To analyze the effect of disaster information on occupant behaviour, this study identified a relationship between 10 major disaster information and 3 occupant behaviour factors in terms of reducing egress time. By referring the relationship, this study conducted an virtual egress experiment with survey on 4 cases, the elderly, intellectual disabled, hearing disabled and visual disabled, to identify disaster information which reduce total egress time effectively. Finally, by analyzing the experiment result, this study proposed the process of disaster information effect on occupant behaviour as complementing insufficient occupant behaviour to ensure the minimum level of safety and maximizing relatively high occupant behaviour to ensure enough level of safety. The results are expected to account for relationship between disaster information and occupant behaviour with more explanatory power in terms of egress time. With further studies of disaster information and group behaviour, these series of studies could provide basic references for disaster information and occupant behaviour.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.4
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• pp.64-75
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• 2010

Gyeongju, with its thousand-year-old history of the Silla Dynasty, is an impressive historical city where beautiful nature of mountains in the background and rivers in its front is getting along with the city landscape. The historic landscape of Gyeongju is divided into three groups: the old town, the ruins preservation region in the southeast of old towns, and the natural landscape region surrounding these regions. The old town region shows a common landscape of which general small cities in Korea may have, while its surroundings display the overlaps of natural and historic landscapes. The special city landscape is presented only in Gyeongju. Nevertheless, the northern area of the old town was built based on the concept of new towns without any height restriction of buildings, damaging the historic landscape of Gyeongju. It is misjudgment by interpreting the cultural heritage as the individual artifact rather than the continuous historic landscape. Since the 1970s when rapid industrialization and urbanization appeared along with the comprehensive development for Gyeongju tourism, the historic landscape has been slowly damaged. There were not enough financial and political supports from the central government, because the project for Gyeongju tourism was focused on the investment on the tourist industry. Now, in order to preserve the historical city like Gyeongju which represents the culture of Korea, the central government should actively engage in its protection. Policies of the central government should be focused on educating people that the historical restoration of Gyeongju is a way of recovering the national pride, and drawing the agreement of people. For its accomplishment, the government should change its policy from economy-oriented to culture-oriented. That is, the cultural policy should be emphasized.