• Journal of Cadastre & Land InformatiX
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• v.49 no.2
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• pp.67-82
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• 2019

The purpose of this study is to analyze the issues and perceptions of smart cities. First, based on the big data analysis platform, big data analysis on smart cities were conducted to derive keywords by year, word cloud, and frequency of generation of smart city keywords by time. Second, trend and flow by area were analyzed by reclassifying major keywords by year based on meta-keywords. Third, emotional recognition flow for smart cities and major emotional keywords were derived. While U-City in the past is mostly centered on creating infrastructure for new towns, recent smart cities are focusing on sustainable urban construction led by citizens, according to the analysis. In addition, it was analyzed that while infrastructure, service, and technology were emphasized in the past, management and methodology were emphasized recently, and positive perception of smart cities was growing. The study could be used as basic data for the past, present and future of smart cities in Korea at a time when smart city services are being built across the country.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.339-347
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• 2008

This study was carried out to assess quantitatively the safety of a tunnel by using critical strains in the ground. Critical strain is a new material property of the ground. It can be applied as deformation limits in the ground due to excavation using the measured displacement at the tunnel construction site. To achieve this purpose, the critical strain concept was reviewed and applied to assess the tunnel safety. First of all, the calculated excavation displacements of a circular tunnel by commercial programs were investigated and inputted into a feedback analysis module to calculate strains in the ground. Then the safety of tunnels was evaluated based on the critical strain concept. Subsequently the measured displacements obtained in the field are utilized practically to assess the safety of tunnels using the critical strain concept. Through this study, it was confirmed that the critical strain concept is useful to assess the safety of tunnels quantitatively.

• Explosives and Blasting
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• v.21 no.2
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• pp.21-30
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• 2003

Currently, the shotcrete used as basic support in the tunnel excavation, has the advantages of maintaining high-level strength in condition of early shooting with thin thickness based on the excavation characteristics of rock mass. Therefore supreme equipment and materials were developed and the great strides have continued. Also, the development of measurement technology and the rocks behaviors of undergound are evaluated in detail and the designs of strength and thickness are made. The reinforcement materials development of new material is carried on. Most of the coal fly ash produced in Korea fire power plant is fly ash and bottom mash. Fly ash has been producing to be applied in many fields such as cement, aggregate, construction, civil, agriculture and fisheries. Also a lot of experiments are actively on the way. Therefore in this experiment, in order to use the fly ash mixed with concrete as a material of shotcrete, the experiment was performed in the best content to reduce the compression strength and the shooting rebound ratio of the excavated surface to use fly ash as a substitute material of concrete. As a result, when 15%.wt substitution was made to the fly ash, about 10% of compression strength and 6% of rebound ratio was reduced.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.4
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• pp.55-65
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• 2012

The purpose of this study is to construct the System Dynamics Model that can analyze urban spatial and temporal change and suggest the policy directions applicable to U-City Planning in Busan based on the SD model. It reviews previous literatures to elicit U-City issues and performs the case study to simulate urban spatial and temporal changes in Busan. The elicited results are connected into the policy directions of U-City planning. It emphasizes the necessity of business model suggestion based on U-City technology and industry not a tool, the U-City model construction that linkages and integrates the existing cities and new cities, and the excavation of U-City service model reflecting social and demographic changes.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.79-88
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• 2009

In this study, it was studied on arching characteristics of a grand section tunnel with pre-steel-rib nail reinforcement. In this study, we examine the adaptation of tunnel plan and the case which is based on the strengthening method for preexistence tunnel and other pre-steel-rib nail while the upper part of cover depth is low or soil condition is bad. When the pre-steel-rib nail as new technology and method reinforces the foundation placed of grand section tunnel, it is much better in strengthening effect, safety and effectiveness than the conventional one. After investigation about the plan pre-steel-rib nail method, construction case and calibration data, it was confirmed and examined about the upper part of tunnel for strengthening the pre-steel-rib nail thereby arching characteristics of grand section tunnel using MIDAS/GTS finite element program. Moreover we present the method that could upgrade the accurate installation interval and adaptation method for strengthening effect to adapt the pre-steel-rib nail method in a foundation placed over a tunnel.

• Journal of The Korean Association For Science Education
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• v.15 no.3
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• pp.332-348
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• 1995

The use of attitude as a psychological concepts dates back to 1918(Thomas and Znaniecki). Assessment of attitudes has been conducted by a number of researchers since then in a wide range of contexts: religion, government, industry, community interrelations, and education; and sociology and psychology. In science, the number of research summaries and meta-analyses points to the significance of the concept of attitude toward science. However, in spite of the wide spread use of attitude assessment in science, many of the existing instruments have severe limitations. Those limitations serve as the rationale for the construction of a new instrument to assess attitudes toward science The term "attitude" and "science" are somewhat ambiguous, taking on different meanings for different people in different contexts. Very often an assessment includes several dimensions of attitude and, therefore, provides no clear idea of what was really measured. As a result there is no consistency with respect to the construct among attitude instruments. To clarify this issue, Gauld(1982), Munby(1983a, 1983b), Blosser(1984) and Haladyna and Shaughnessy(1982) offer some guiding descriptions. Attitude as it relates to science is divided into two areas-scientific attitude and attitude toward science. Scientific attitude refers to a particular approach a person assumes for solving problems, for assessing ideas and information, and for making decisions. It includes such scientific methods and predispositions as objectivity, suspended judgement, critical evaluation, and skepticism. Munby(1983a, 1983b) characterized scientific attitude as thinking as scientists do, that is, acting on evidence in a disciplined way. Attitude toward science. on the other hand, may address scientific attitudes, scientists, scientific careers, methods of teaching science, scientific interests, parts of curriculum, or the subject of science in the classroom (Blosser,1984). It may refer to belief about processes, theoretical products, technological products, or the science-technology relationship (Munby, 1983).

• Smart Structures and Systems
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• v.17 no.4
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• pp.593-610
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• 2016

In this study, an innovative and smart glass fiber-reinforced polymer (GFRP) hybrid bar was developed for stronger durability of concrete structures. As comparing with the conventional GFRP bar, the smart GFRP Hybrid bar can promise to enhance the modulus of elasticity so that it makes the cracking reduced than the case when the conventional GFRP bar is used. Besides, the GFRP Hybrid bar can effectively resist the corrosion of conventional steel bar by the GFRP outer surface on the steel bar. In order to verify the bond performance of the GFRP hybrid bar for structural reinforcement, uniaxial pull-out test was conducted. The variables were the bar diameter and the number of strands and pitch of the fiber ribs. Tensile tests showed a excellent increase in the modulus of elasticity, 152.1 GPa, as compared to that of the pure GFRP bar (50 GPa). The stress-strain curve was bi-linear, so that the ductile performance could be obtained. For the bond test, the entire GFRP hybrid bar test specimens failed in concrete splitting due to higher shear strength resulting in concrete crushing as a function of bar deformation. Investigation revealed that an increase in the number of strands of fiber ribs enhanced the bond strength, and the pitch guaranteed the bond strength of 19.1 mm diameter hybrid bar with 15.9 mm diameter of core section of deformed steel the ACI 440 1R-15 equation is regarded as more suitable for predicting the bond strength of GFRP hybrid bars, whereas the CSA S806-12 prediction is considered too conservative and is largely influenced by the bar diameter. For further study, various geometrical and material properties such as concrete cover, cross-sectional ratio, and surface treatment should be considered.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.181-189
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• 2017

The purpose of this research is to set a standard for deciding competitive marketing prices of new supplying apartment houses and to analyze decision factors in sale price of supplying apartment houses with Analytic Hierarchy Process; the resulted model does not use the method that joins the land cost and the cost of construction together, but the method that compares the sales prices of surrounding apartments. This research tries to set a standard for decision of the prices of newly supplying apartment houses by classifying the determinants into the $1^{st}$ step(4 factors), the $2^{nd}$ step(9 factors), and the $3^{rd}$ step(25 factors). According to the process, the relative importance of decision factors in the sale prices is determined and this should be used as the index of sale prices for newly supplying apartment houses when the houses are provided. In addition, through the $2^{nd}$ step including 9 factors, the comparative model for sale prices is defined and the model is presented to be applied in the real business. Subsequent study additionally considering the factors apart from marketing which tries to find a generalized standard needs to be conducted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.197-204
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• 2005

Multipurpose Floor Level Joint(MFLJ) is a new construction technology system which was developed in domestic. By using this system, it is possible not only to absorb the deformation at expansion joint due to shrinkages of concrete but also to make ease the floor leveling during the concrete casting at floor. The system consists of two elements, supporting devices and rails. Their structural capacities were verified through several experimental programs, such as compressive strength test of support and bending test of rail. The purpose of this paper is to evaluate the deformation absorbing capacity of the floor level joint. An experimental work was carried out to simulate the deformation condition at the joint and the test result was analyzed and evaluated. In addition, FEM analysis for expansion joint of typical building was also performed to predict the real behavior of MFLJ. The test results showed that MFLJ has sufficient deformation capacity required to act as expansion joint.

• Journal of Convergence for Information Technology
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• v.10 no.7
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• pp.147-152
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• 2020

The research is carried out to analyze the cost-effectiveness of blasting patterns with regard to the diameters and design of blasting holes. Blasting patterns for single diameter array, and mixed diameter array were comparatively analyzed with regard to drilling and charging time, and materials required. The number of blasting holes required for single array pattern and mixed array pattern were 138 and 93 holes, respectively. From the drilling time analysis, reduction in time and its efficiency of mixed pattern were 139 minutes and 25%, respectively, in comparison with single pattern. Charging time reduction and its efficiency of mixed blasting pattern were evaluated as 22.5 minutes per worker and 33%, respectively, compare to single blasting pattern. The explosive quantities of G1 and G2 required for single array patterns were 270 and 30, while those were 222 and 20 for mixed array patterns for tunnelling 4m. And single pattern required 45 more detonators than the mixed pattern. The evaluation of material required can also be positive parameter for cost reduction of tunnel construction.