• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.23-34
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• 2015

Recently a new damper system with Kogome truss structure was developed and its mechanical properties were verified based on the laboratory test. This paper presents a Kagome truss damper external connection method for seismic strengthening of RC frame structural system. The Kagome external connection method, proposed in this study, consisted of building structure, Kagome damper and support system. The method is capable of reducing earthquake energy on the basis of the dynamic interaction between external support and building structures using Kagome damper. The pseudo-dynamic test, designed using a existing RC frame apartment for pilot application of LH corporation, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and response ductility. Test results revealed that the proposed Kagome damper method installed in RC frame enhanced conspicuously the strength and displacement capacities, and the method can resist markedly under the large scaled earthquake intensity level.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.1
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• pp.38-46
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• 2012

This study carried out current status, characteristics, and problems of coastal environment management on semi-enclosed Masan Bay in Korea and suggests cost-effective and eco-friendly water quality management policy. The pollutants from terrestrial sources into the Bay have apparently environmental pollution problems, such as eutrophication, red tide, and hypoxia. The carrying capacity of the Bay is estimated by hydrodynamic model and ecosystem model, material circulation including bivalve in ecosystem is analyzed by the growth model of bivalve. The resulting reduction in the input load was found to be 50~90%, which is unrealistic. When the efficiency of water quality improvement through bivalve farming was assessed based on the autochthonous COD, 30.7% of the total COD was allochthonous COD and 69.3% was autochthonous COD. The overall autochthonous COD reduction rate by bivalve aquaculture farm was found to be about 6.7%. This study indicate that bivalve farming is about 31% less expensive than advanced treatment facilities that remove both nitrogen and phosphorous.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.41-49
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• 2014

In this study, experimental research was carried out to evaluate the structural performance of the reinforced concrete beam using hybrid retrofitting with two materials (groove and embedding FRP rod, CFRP sheet) in existing reinforced concrete buildings. Seven reinforced concrete beams, retrofitted groove and embedding FRP rod (NER series) and groove and embedding FRP rod with CFRP sheet (NERL series), and standard specimen (NBS) were constructed and tested under monotonic loading. Design parameters of test specimens are the amount of groove and embedding FRP rod and lapping CFRP sheet. Test results showed that the maximum load carrying capacity of specimens with groove and embedding FRP rod and groove and embedding FRP rod with CFRP sheet (NERL series) were increased the by 12~46% and 22~77% respectively in comparison with the standard specimen NBS. Test specimens NER series were failed with the adhesion slip and concrete cover separation. And test specimens NERL series were failed with the adhesion slip due to the confining effect of lapping CFRP sheet.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1995.10a
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• pp.111-121
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• 1995

In Extracting the dynamic parameters for estimating the load carrying capacity and integrity of bridges, both the instrumentation and the processing the data plays important role . When the fixed point can not be secured, it is difficult and expensive to measure dynamic displacements. Even if the displacement is obtained through the integration of the acceleration data, the results can be quite different from the real behavior, because the main frequency contents can be leaked during discretized data processing. The instrumentation is used for measurements, and every measurement involves error and uncertainty, such as systematic, conformance, environmental, observational, sampling, and ranmom error. Systematic and conformance error can be remedied through the proper sellection and installation of the instruments, but sampling and random errors could not have been corrected properly and it becomes the limitation for using acceleration data. In this paper, the errors which can be occurred in numerical processing of dynamic data are referred, and the method to sellect proper sampling rate for the structural frequency range are proposed. Using the proposed method, the displacement response of the structures can be economically obtained from the measured acceleration record, and this procedure can be used properly to estimate the integrity of the bridges and infrastructures subjected to dynamic loads.

• Journal of the Korea Society of Computer and Information
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• v.11 no.2 s.40
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• pp.187-199
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• 2006

This paper proposes the design of user centric pavilion information guide system based on mobile device such as PDA. which is composed of system interface factors as user wants. The suggested information guide system is convenient for user carrying because it is based on PDA mobile device and the used liquid browser system makes all data information displayed on a small screen in contrast with the other browser system. Indeed, factors of system interface can be re-composed by user interaction. And this system can effectively provide the detail information about the exhibited objects as various media data such as text, image, voice, music, video etc. The proposed system is made up of media database server. mobile system control server and mobile system interface which accepts user interaction and displays the information. Each system is networked based on TCP/IP and uses XML (extensible Markup Language) and JAVA 2 micro edition to be able to update data. This feature enhances a wide use to be able to load this system on the any mobile device.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6A
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• pp.457-464
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• 2011

An experimental study was performed to evaluate the possibility of using stiff type PolyUrea(PU) on RC slab as a strengthening material. Stiff type PU(STPU) was sprayed on the bottom surface of the slab specimens, which were then attached with CFRP or GFRP sheets. Also the evaluation of the bond capacity, the single most influential parameter on strengthening of RC structures, was carried out the flexural capacity evaluation test results showed that the load carrying capacity of the PU specimen was greater and less than the unstrengthened and FRP sheet attached specimens, respectively. The STPU specimens showed a ductile flexural behavior in the plastic displacement range. With respect to bond capacity, the bond strength of all of the specimen exceeded the code required bond strength of 1.5 MPa. Also, the STPU sprayed specimen without using epoxy resin did not peel off when the tensile grip was applied for testing. The stability of the PU bond failure indicate a good bond strength of PU when applied to concrete.

• Journal of the Korea Concrete Institute
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• v.25 no.2
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• pp.137-144
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• 2013

The use of fiber-reinforced polymer (FRP) reinforcing bars in concrete structures has been increased as an alternative of steel reinforcement which has shown greater vulnerability to corrosion problem. However, the long-term performance of concrete members with FRP reinforcement is still questioned in comparison to the used of steel reinforcement. This study presents the results of an experimental study on the long-term behaviors of GFRP (glass fiber reinforced polymer) bar reinforced concrete beams after exposed to accelerated aging in an environmental chamber with temperature of $46^{\circ}C$ ($115^{\circ}F$) and 80% of relative humidity up to 300 days. The objectives of this research was to compare strength degradation and change of ductility between GFRP reinforced concrete beams and steel reinforcement beams after accelerated aging. Two types (wrapped and sand-coated surface) of GFRP bars and steel were reinforced. in concrete beams. Test results show that the failure modes of GFRP bar reinforced concrete beams are very similar with traditional RC beams, and the change of load-carrying capacity of steel reinforcing concrete beam is greater than that of GFRP bar reinforcing concrete beam under the accelerated aging. Test result also shows that the use of GFRP reinforcing in concrete could be introduced more brittle failure than that of steel reinforcing for practical application. The deformability factor up to compression failures indicates no significant variation before and after exposure of accelerated aging.

• Journal of the Korean Solar Energy Society
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• v.35 no.2
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• pp.73-83
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• 2015

When it comes to these buildings for business use, cooling load during summertime was reported to have great importance which, as a result, impressively increased interest in Solar Heat Gain Coefficient (SHGC). Such SHGC is considered to be lowered with the help of colors and functions of glass itself, internal shading devices, insulation films and others but basically, these external shading devices for initial blocking that would not allow solar heat to come in from outside the buildings are determined to be most effective. Of many different external shading devices, this thesis conducted an analysis on Exterior Venetian Blind. As for vertical shading devices, previous researches already calculated SHGC conveniently using concepts of sky-opening ratios. However in terms of the Venetian Blind, such correlation is not possibly applied. In light of that, in order to extract a valid correlation, this study first introduced a concept called shape factor, which would use the breadth and a space of a shade, before carrying out the analysis. As a consequence, the concept helped this study to find a very similar correlation. Results of the analysis are summarized as follows. (1) Regarding SHGC depending on the surface reflectance of a shade, an average of 2% error is observed and yet, the figure can always be ignored when it comes to a simple calculation. (2) As for SHGC of each bearing, this study noticed deviations of 4% or less and in the end, it is confirmed that extraction can be achieved with no more than one correlation formula. (3) When only the shape factor and nothing else is used for finding a correlation formula, the formula with a deviation of approximately 5% or less is what one would expect. (4) Since the study observed slight differences in bearings depending on ranges of the shape factors, it needed to extract a weighted value of each bearing, and learned that the smaller the shape factor, the wider the range of a weighted value. The study now suggests that a follow-up research to extract a simple calculation formula by dealing with all these various inclined angles of shade, solar radiation conditions of each region (the ratio of diffuse radiation to direct radiation and others) as well as seasonal features should be carried out.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.97-107
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• 2014

Finite element modelling and analysis were conducted for the roll-type steel mats which were placed on loose sand and subjected to a standard truck wheel load in this study. The roll-type steel mats mean that the steel mats can be folded as a circle shape for the carrying to fields in cold regions where workability is limited and are developed for a rapid rehabilitation method for roadway across soft ground which is caused by thawing during the summer season in cold regions. The model is composed of link elements to simulate nonlinear behavior of connections between steel mats, thick shell elements to have flexural stiffness of the steel mats, and springs to simulate characteristics of foundation soils. The structural behaviors of the shell, link elements, and springs were verified at each modelling step through experiment and analysis. Beam and shell analysis without the link elements were conducted and compared to results obtained from the model presented in this study. Significant vertical displacement is shown in the shell model with hinge connections. Therefore, the results demonstrate that the analysis model for the roll-type steel mats on loose sand needs further detail parametric studies.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.129-136
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• 2006

Engineered mixtures, which consist of rigid sand particles and soft fine-grained rubber particles, are tested to characterize their small and large-strain responses. Engineered soils are prepared with different volumetric sand fraction, sf, to identify the transition from a rigid to a soft granular skeleton using wave propagation, $K_{o}-loading$, and triaxial testing. Deformation moduli at small, middle and large-strain do not change linearly with the volume fraction of rigid particles; instead, deformation moduli increase dramatically when the sand fraction exceeds a threshold value between sf=0.6 to 0.8 that marks the formation of a percolating network of stiff particles. The friction angle increases with the volume fraction of rigid particles. Conversely, the axial strain at peak strength increases with the content of soft particles, and no apparent peak strength is observed in specimens when sand fraction is less than 60%. The presence of soft particles alters the formation of force chains. While soft particles are not part of high-load carrying chains, they play the important role of preventing the buckling of stiff particle chains.