• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.81-84
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• 2005

Due to increased demands for durable and high-performance concrete structures, the use of admixtures has become essential. In this paper, material properties, and durability of concrete mixed with natural inorganic minerals(R-1) are obtained from test results. Through the comparisons with OPC(Ordinary Portland Cement) concrete, the R-1 concrete shows improved compressive strength and durability.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.256-261
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• 1995

Large-scaling recycling of demolished concrete will concrete will contribute not only to the solution of a growing waste disposal problem, it will also help to consweve natural resoures of sand and gravel and to secure future supply of reasonly priced aggregates for building and other construction purposes within large urban areas. Because recycled aggregate particles consits of substantial amount of relatively soft cement paste component, it is less resistant to mechanical actions. With this view in mind, to obtain a reference data for the development of recycling system and to a basic data the guiedline of recycled aggregate concrete construction and engineering properties of recycled aggregate concrete according to the factors, such as blending ratio of recyced aggregete with the natural aggregate, addition to the factors, such as blending ratio of recycled aggregete with the natural aggregate, addition of flyash, water coment ratio.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.11-16
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• 2002

The differential equations governing free vibrations of the elastic, horizontally curved beams with unsymmetric axis are derived in Cartesian coordinates rather than in polar coordinates, in which the effect of torsional inertia is included. Frequencies are computed numerically for the sinusoidal curved beams with both clamped ends and both hinged ends. Comparisons of natural frequencies between this study and SAP 2000 are made to validate theories and numerical methods developed herein. The convergent efficiency is highly improved under the newly derived differential equations in Cartesian coordinates. The lowest four natural frequency parameters are reported, with and without torsional inertia, as functions of three non-dimensional system parameters: the horizontal rise to chord length ratio, the span length to chord length ratio, and the slenderness ratio.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1001-1006
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• 2004

Railroad disasters are frequently occurred by man-made causes or natural causes. In general, man-made causes are illegal construction practices, deterioration with the lapse of time and railroad crossing accidents, and natural causes are rainfall. snow, wind, earthquake, etc. Of cause, railroad disasters by man-made causes are prevented from keeping the safety principle, constructing multi-level crossing, securing enough men of ability and financial resources and making a thorough check using equipments with high capacity. And railroad disasters by natural causes are also minimized by construction of disaster prevention facilities, introduction and operation of general disaster prevention system and reasonable train passage control. Therefore, to setup the criterion of train passage control for train safety at railroad bridge under heavy rainfall, risky factors, national and oversea criteria under such circumstances are reviewed and a scheme to setup the criterion is suggested.

• Advances in concrete construction
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• v.5 no.4
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• pp.303-311
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• 2017

The concrete industry of developing countries like India consumes majority of natural resources. The increase in population has necessitated the construction of more and more structures. Further many structures have completed their life span or have undergone damages thus warranting the demolition of these structures. India produces approximately 23.75 million tons of recycled concrete aggregate (RCA) annually. The natural resources are depleting at a higher rate with the increasing demand of concrete industry. This difficulty can be reduced with the use of RCA in land fill and concrete manufacturing. Use of RCA can provide cost savings and better energy utilization. This paper presents mechanical behavior of concrete comprising successively recycled concrete aggregate. Mechanical properties of recycled concrete get affected with number of recycling. In mix design successive recycled concrete aggregate (SRCA) was used in place of natural aggregates (NA) with 100% replacement. The test results of the compressive, flexural strength and pulse velocity were obtained for 14 and 28 days of curing age which showed significant improvement in results.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.177-184
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• 2020

This study evaluates safety assessment before and after repair of Seonamsa temple seungseon bridge, which refer to the representative Hongye bridge in Korea. In this approach natural frequency of the structure were considered in the modeling procedure. Trial & error method is applied to obtain the approximate natural frequency before and after retrofit construction. Stiffness of the actual structure was examined to account for the dynamic characteristics of Hongye bridge measured in the field and adjusting parameters in computer modeling. The safety and usability of the stone structure in terms of load bearing capacity and displacement were examined.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.702-703
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• 2015

Currently, according to the climate change, serious damage by Typhoon has been occurred in the world. In this respect, the research on the damage prediction model to minimize the damage from various natural disaster has been conducted in several developed countries. In the case of U.S, various damage prediction models of buildings from natural disasters have been used widely in many organizations such as insurance companies and governments. In South Korea, although studies regarding damage prediction model of hurricane have been conducted, the scope has been only limited to consider the property of hurricane. However, it is necessary to consider various factors such as socio-economic, physical, geographical, and built environmental factors to predict the damages. Therefore, to address this issue, correlation analysis is conducted between various variables based on the data of hurricane from 2003 to 2012. The findings of this study can be utilized to develop for predicting the damage of hurricane on buildings.

• Computers and Concrete
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• v.12 no.1
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• pp.79-90
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• 2013

In this study, dynamic characteristics such as natural frequencies, mode shapes and damping ratios of RC frame is determined for different construction stages using Operational Modal Analyses method under ambient vibration. Full scaled, one bay and one story RC frames are selected as an application for different construction stages such as plane, brick in-filled and brick in-filled with plaster. The RC frame is vibrated by natural excitations with small impact effects and the response signals are measured using sensitive accelerometers during ambient vibration tests. Measurement time-frequency span and effective mode number are determined by considering similar studies in literature. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, output-only system identification technique is employed namely; Enhanced Frequency Domain Decomposition technique in the frequency domain. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of RC frames.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.107-108
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• 2017

In this search, by evaluating the field applicability of soil mixed pavement of Red mud is mixed into the soil mixed pavement field applicability, and tries to present the basic data about the site application of recycling of red mud and low carbon construction material to. As a result, the conventional soil concrete organization standards (SPS-KSCICO-001: 2003) meets the criteria for parking lot, making use of red mud, natural color as well as the natural loess is expressed.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.503-509
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• 2012

In this study, the potential use of indigenous natural loess(Hwangtoh) as a new construction material, via alkali activation in conjunction with microwave heating, was investigated. Hwangtoh pastes with three different mix proportions of varying alkali liquid concentrations at a constant liquid-to-Hwangtoh ratio of 0.55 were prepared. Through the investigation it was found that it is possible to prepare Hwangtoh paste with $19.02N/mm^2$ at the age of 4 hours with the alkali solution of 8M NaOH and 1:4.5 mass ratio of liquefied $Na_2SiO_3$ at the curing temperature of $60^{\circ}C$ by microwave heating. The strength development at early age of the alkali activated Hwangtoh paste specimens may be attributed to both a higher rate of reaction and moisture evaporation due to microwave heating.