• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.138-145
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• 2017

The purpose of this study is to establish a reasonable analytical method for the estimation of overall behavior characteristic from cracking to yielding of rebar and crushing of concrete and seismic performance of reinforced concrete shear wall with high-strength reinforcing bar. A total of 8 specimens of reinforced concrete walls which have constant aspect ratio and a variety of variables such as reinforcement ratio, reinforcement yielding strength, reinforcement details, concrete design strength, section shape and whether lateral restraint hoop were selected and the analysis was performed by using a non-linear finite element analysis program (RCAHEST) applying the proposed constitutive equation by the authors. The mean and coefficient of variation for maximum load from the experiment and analysis results was predicted 1.04 and 8%. The mean and coefficient of variation for displacement corresponding maximum load from the experiment and analysis results was predicted 1.17 and 19% respectively. The analytical results were predicted relatively well the fracture mode and the overall behavior until fracture for all specimens. These results are expected to be used as basic data for application of high-strength reinforcing bar to design codes in the future.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.67-76
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• 2016

The railway bridge abutment subjected to the lateral earth pressure is a sensitive structure that is affected by backfill materials, installation methods, compaction, and drainage system and so on. The several design loads for the bridge abutment design consist of traffic loading on bridges and vertical & lateral force due to surcharge load at backfill. Especially, the lateral earth pressure of design load components is important and considered in the design of geotechnical engineering structure such as bridge abutment wall. The determination of cross section for abutment is finally determined with calculating external stability and member force of abutment wall structures. In this study, the abutment wall height is 12m and the optimal cross section of abutment wall has been determined that satisfies an external stability for abutment structure through friction angles of 35, 40, and 45 degrees of backfill materials. The external stability and member force of abutment wall with friction angle of backfill materials and were calculated and construction cost of each abutment wall structures was compared. It found that the construction cost was reduced from 2.2 to 8.4% with friction angle of backfill materials.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.1
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• pp.29-39
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• 2016

The purpose of this study was to suggest the improvement of the Mountainous Landscape Impact Review(MLIR) system for the conservation and eco-friendly use of mountain scenery. In order to understand the status of the MLIR system, a comparative analysis was conducted of the MLIR official guidelines and the 100 MLIR reports submitted to the Korea Forest Service from 2011 to 2013. In addition, an Importance-Performance Analysis(IPA) was conducted to take into account stakeholder opinions and to determine the first priorities to be improved upon in operation and functions of the MLIR system. The results of the IPA in evaluating the MLIR system showed that the components in the MLIR system that should be primarily improved are mountainous landscape resource inventory, objective and quantitative selection of viewpoints, and a checklist for examining the damage expected in mountainous lands. To Revitalize the Mountainous Landscape Impact Review system, the professional knowledge and experience of the stakeholders should be enhanced by education and training in the MLIR system over the short-term, while the effective functioning of the MLIR system should be reinforced by differentiation and connectivity of the MLIR system with similar institutions, and by emphasizing the uniqueness and properties of mountainous landscapes over the long-term.

• Journal of the Korean GEO-environmental Society
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• v.16 no.11
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• pp.13-19
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• 2015

Construction materials using soil which is the most common material around us have many advantages, but their long-term durability and sensation of walking as pavements have problems. Therefore, they are used after compaction or mixed with various hardening agents such as lime and cement for strength enhancement. However, studies on the behavior of pavement materials mixed with environment-friendly hardening agents or admixtures to improve walking property are still insufficient. In this study, therefore, in order to evaluate the appropriate mixing ratio and field application characteristics of pavement materials using mixed soils with environment-friendly hardening agents and natural materials such as wood chips, mechanical tests were performed to evaluate the rational mixing ratios and the ball test was performed as an elasticity test to evaluate the field applicability. The results suggest that the content of wood chips should be selected at 1.5% or lower according to the purpose of the structure, and the hardening agent at 10~15%. The evaluation results for GB/SB coefficient ratio which indicates the walking property show that the appropriate mixing ratio of the hardening agent in terms of the sensation of walking is 15% of lower, but different mixing ratios should be chosen according to the proportion of wood chips.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.111-118
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• 2018

In case of excavation of the tunnel under weak ground conditions, such as fault zone, leg pile reinforcement with the purpose of suppressing tunnel crown settlement and side wall displacement is commonly applied. There are convergence, crown settlement, leg settlement, and the axial force of leg as a main factor for confirming the safety of support considering the installation angle and length of leg pile reinforcement according to the increase in rate of change of tunnel cross-section. In particular, the influence of right corner settlement, among variables for safety confirmation during excavation, has been analyzed as the dominant factor in the most important priority management showing larger displacement tendency than the increase in rate of the cross-section. And, it was analyzed that the occurrence tendency of axial force on leg pile reinforcement showed the influence of behavior according to the friction support concept mechanism of the pile reinforcement rather than the increase in rate of tunnel cross-section, as it showed a small increase compared to the increase rate of the tunnel cross-section which did not show a great correlation from the viewpoint of the change of the axial force by the length of each leg pile reinforcement with regards to the change in rate of increase in tunnel cross-section. If a certain length of the leg pile reinforcement is selected based on the above grounds, even if the cross-section of the tunnel in poor ground condition is somewhat larger, it has been proved to be a more reasonable method considering the workability and economical efficiency by not extending the length of the leg pile reinforcement by force.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.99-112
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• 1999

By using 92 values of lateral earth pressure coefficient(K) measured in Korea, the tendency of K with varying depth is analyzed and compared with the range of K defined by Hoek and Brown. The horizontal stress is generally larger than the vertical stress in Korea : About 84 % of K values are above 1. In this study, the theory of elasto-plasticity is applied to analyze the variation of K values, and the results are compared with those of numerical analysis. This reveals that the erosion, sedimentation and weathering of earth crust are important factors in the determination of K values. Surface erosion, large lateral pressure and good rock mass increase the K values, but sedimentation decreases the K values. This study enable us to analyze the effects of geological processes on the K values, especially at shallow depth where underground excavation takes place. A neural network expert system using multi-layer back-propagation algorithm is developed to predict the K values. The neural network model has a correlation coefficient above 0.996 when it is compared with measured data. The comparison with 9 measured data which are not included in the back-propagation learning has shown an average inference error of 20% and the correlation coefficient above 0.95. The expert system developed in this study can be used for reliable determination of K values.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6D
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• pp.793-801
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• 2011

Existing specifications of road pavement require contractors to meet only materials and construction conditions regardless of pavement life. There are limitation of developing road pavement technology and possibility causing dispute between ordering organization and contractor with this type of specification. Research efforts to introduce performance warranty contracting are in progress in the field of road pavement to improve the problems. The performance warranty contracting gives the contractors opportunity to select materials and construction methods as they like. But they should satisfy a certain level of performance during a given period. The performance indicator and threshold value of pavement which are main elements of the warranty specification should be defined first to introduce the performance warranty contracting successfully. In this study, the performance indicator, threshold value, and warranty duration of asphalt pavement were investigated by reviewing literatures on performance warranty contracting of some states of the US. Major distresses influencing the performance of the asphalt pavement were investigated at 24 national expressway lines and national highway lines in 16 regions, and the data were analyzed to be compared to the cases of the US. Development of rational performance warranty specification for domestic asphalt pavement is expected based on the research results.

• Journal of Science Education
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• v.35 no.2
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• pp.250-261
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• 2011

The purpose of this study is to analyze how the content elements of the environment education are displayed between related subjects in elementary school curriculum and find a desirable direction of the environment education. Major subjects that handle the components of the environment education include science, physical education, social studies, ethics, and practical arts. Among these subjects, science aims for the ecological perspective, social studies aims for rational decision making and practical behaviors, and ethics aims for the correct formation of environmental ethics and values. In the component ratio of the environment education, the domains of the natural environment, environmental ethics, environmental pollution, environmental protection and measure were higher. In the formation of content elements according to grades, the connectivity of the environment curriculum has been relatively well secured in the order of the learning about the environmental components, awareness on environmental problems and the measures and efforts to overcome environmental problems. Based on the findings above, the followings are proposed for future environment curriculum in elementary school. First, it is necessary to increase the ratio of the ecological perspective based on science and coordinate the period to suggest this contents. Second, it is necessary to complement the contents of social studies regarding green growth and sustainable development which have become global issues in the environment education. Third, Pan-curriculum and integrated discussions to prepare multi-academic and interdisciplinary environment curriculum have to be preceded and through this process it is necessary to set the target of environment education and select the content elements of the curriculum.

• Journal of The Korean Association For Science Education
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• v.30 no.4
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• pp.472-486
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• 2010

The surveys for public awareness in relation to socio-scientific issues (SSI) have been limited to several topics such as public perception of risks about the issues and preference for some policies. To illuminate the public science culture literacy about SSI from a holistic perspective, this study aimed to develop an indicator system. For this purpose, the issue on climate change, which is currently one of the biggest issues worldwide, was adopted as a specific SSI and the framework centering on climate change was developed. Science culture literacy about SSI was defined as a lifestyle to identify SSI from various viewpoints and to cope with problems related to SSI appropriately. In the framework proposed, individual science culture indicators are divided into Potential and Activity area. The Potential consists of categories of Interest, Opinion and Understanding, whereas the Activity is composed of categories of Learning and Practice. To examine the reliability and validity of this framework statistically, the developed questionnaire was reviewed by science educators, environment experts and atmospheric scientists and was used to asked 777 secondary students. Based on the results of statistical analyses, the framework was modified and it consequently had 2 areas, 5 categories, 15 sub-categories, 34 indicators and 63 items. It is expected that the framework of science culture indicators for SSI could be used as a measurement tool for public awareness about various SSI topics.

• Journal of the Korea Convergence Society
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• v.11 no.6
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• pp.237-248
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• 2020

The purpose of this study is to measure the agricultural product market efficiency of the three e-commerce platforms from the perspective of consumer price fairness perception, analyze the quality and price gap of invalid brands, and help agricultural products enterprises to formulate reasonable price strategies. The characteristics of farm products sold in e-commerce platforms(quality, origin, taste, safety level) were selected as output indicators and the prices of products were selected as input indicators to evaluate the efficiency of the market through DEA analysis. According to the analysis, JD mall has the largest proportion of effective brands, while YHD.com has the highest average market efficiency, and northeast rice has the largest difference in average efficiency among the three platforms. The results show that price inefficiencies still exist in the electronic market. The development of online market for agricultural products should pay attention to consumer price fairness and pay attention to the coordination between price and quality. The limitation of this paper is that it does not focus on the influence of words of mouth marketing in internet market and consumer experience, which can be the future research direction.