• Journal of the Korean Geotechnical Society
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• v.39 no.4
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• pp.31-44
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• 2023

A base expansion micropile was developed to improve the bearing capacity of the micropile, which bears a simple device installed at the pile base. Under an axial load, this base expansion structure radially expands at the pile tip and attaches itself around ground, compressing the boring wall in the construction stage. In this study, conventional and base expansion micropiles were constructed in the weathered rock where micropiles are commonly installed. Further, field load tests were conducted to verify the bearing capacity enhancement effect. From the load test results, it was revealed that the shaft resistance of base expansion micropiles was about 12% higher than that of conventional micropiles. The load transfer analysis results also showed that compared to conventional micropiles, the unit skin friction and unit end bearing of base expansion micropiles were 15.4% and 315.1% higher, respectively, in the bearing zone of the micropile.

• Korean Journal of Construction Engineering and Management
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• v.24 no.2
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• pp.24-36
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• 2023

OSC is drawing attention to supplement limitations such as productivity problems and on-site safety and quality problems of existing on-site labor-oriented construction production methods. In order to activate the introduction and use of OSC in the domestic construction market, it is important to innovate the technology applied to each stage of OSC process (design and engineering, factory manufacturing, site assembly, and maintenance), but it is also necessary to develop a project management method suitable for OSC method. However, research related to OSC currently being conducted in Korea is mainly in terms of related technology development, and research on deriving project management measures for the success of OSC projects is insufficient. Therefore, it is time for research on deriving a project management plan based on the core success factors of the OSC project. Therefore, by conducting importance-performance analysis on 69 OSC critical success factors derived from the previous study, the study was conducted to derive key improvement factors for OSC introduction and utilization improvement and to provide implications for this. The results of this study are expected to have useful implications for the R&D planning and policy-making process for OSC activation in the future.

• Tunnel and Underground Space
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• v.33 no.3
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• pp.109-125
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• 2023

Disposal repository for high-level radioactive waste secures its safety by means of engineered and natural barriers. The performance of these barriers should be tested and verified through various aspects in terms of short and/or long-term. KAERI has been conducting various in-situ demonstrations in KURT (KAERI Underground Research Tunnel). After completing previous experiment, a conceptual design of an improved in-situ experiment, i.e. K-COIN (KURT experiment of THMC COupled and INteraction), was established and detailed planning for the experiment is underway. Preliminary characterizations were conducted in KURT for siting a K-COIN test site. 15 boreholes with a depth of about 20 m were drilled in three research galleries in KURT and intact rock specimens were prepared for laboratory tests. Using the specimens, physical measurements, uniaxial compression, indirect tension, and triaxial compression tests were conducted. As a result, specific gravity, porosity, elastic wave velocities, uniaxial compressive strength, Young's modulus, Poisson's ratio, Brazilian tensile strength, cohesion, and internal friction angle were estimated. Statistical analyses revealed that there did not exist meaningful differences in intact rock properties according to the drilled sites and the depth. Judging from the uniaxial compressive strength, which is one of the most important properties, all the specimens were classified as very strong rock so that mechanical safety was secured in all the regions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.584-585
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• 2021

As the production of new and renewable energy such as solar and wind power has diversified, microgrid systems that can simultaneously produce and consume have been introduced. In general, a decrease in electricity prices through solar power is expected in summer, so producer protection is required. In this paper, we propose a transparent and safe gift power transaction system between users using blockchain in a microgrid environment. A futures is simply a contract in which the buyer is obligated to buy electricity or the seller is obliged to sell electricity at a fixed price and a predetermined futures price. This system proposes a futures trading algorithm that searches for futures prices and concludes power transactions with automated operations without user intervention by using a smart contract, a reliable executable code within the blockchain network. If a power producer thinks that the price during the peak production period is likely to decrease during production planning, it sells futures first in the futures market and buys back futures during the peak production period to make a profit in the spot market. losses can be compensated. In addition, if there is a risk that the price of electricity will rise when a sales contract is concluded, a broker can compensate for a loss in the spot market by first buying futures in the futures market and liquidating futures when the sales contract is fulfilled.

• Industry Promotion Research
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• v.8 no.1
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• pp.103-110
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• 2023

This study targeted KakaoTalk app users, mainly in Seoul and the metropolitan area, and verified the factors that had a significant impact on the intention to continuously use the app through KakaoTalk contents. Among various content characteristics, five variables were used to verify the variables that had the greatest influence on the intention to continue using, and the ones that did not. As a result of testing the five hypotheses, it was found that convenience, enjoyment, informativeness, and perceived usefulness had a significant positive(+) effect on the intention to continue using, but intimacy did not. From this, it can be determined that the majority of users use the app content because it is useful and informative, rather than because they have a sense of familiarity. In this way, the purpose of this study is to provide empirical help to factors closely related to the intention of continuous use in deriving priorities to be considered in the service planning stage as well as in terms of technical design of contents when developing mobile apps in the mobile app industry as a whole and in the field in the future. I want to provide it, but there is a meaning.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.769-777
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• 2023

Globalization has brought about rapid economic, technological, and cultural changes. In order for countries around the world to communicate, recognize and understand globalization, creativity or planning ability can be used to code. In this paper, we would like to present and prove a data analysis that can solve world problems. In the global market, the value of goods or services increases with connectivity. This connection is becoming one of the factors that increase the value of culture. Changes taking this into account promoted cultural spread and innovative growth, and increased productivity and competitiveness in each region of the world. This paper compares the income of the middle class in the United States on the impact of globalization and anti-globalization on cultural spread and innovative growth. Globalization has created an environment in which various elements of K-culture can interact and spread. Through the Internet, social media, and international travel, globalization has had a positive impact on Korea's innovative growth. In areas such as economic activity, technological innovation, and creative industries, globalization has facilitated new tech and approaches, Through this, it changed the existing economic model and contributed to exports K-culture with a new middle class model. However, globalization in the cultural industry can result in the loss of regional characteristics & individuality, which can lead to the middle class cultural unification and alienation(chasm). As a result of the empirical analysis of K-exports for the middle income in the United States, cultural diffusion and innovation must be developed even in anti-globalization. With these industrial changes the soft power value of the Korean Wave proves that it can create value for use for the middle class of major exporting countries.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.1019-1023
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• 2006

The slope information based on DEM is very useful for urban planning, landscape, road design and water resource areas such as rainfall-runoff and soil erosion estimation. The resolution of slope, which is from DEM, can be variously decided by an application fields and the kinds of modeling method. In particular, the more decreased resolution makes the more decreased slope value because of the increased horizontal distance. This study presents slope evaluation method by aggregation method based on discharge and Manning's velocity equation to advance the loss of slope information in according to the resolution, and then applied it to calculate topographic factors of soil erosion model. As a result, conventional method shows 34.8% errors but aggregation method shows 12.6% errors. This study selected up-, middle-, and downstream region in watershed and analyzed the capability of aggregation method in order to estimate the influence of topographic characteristics. As a result of estimation, aggregation method shows more advanced results than conventional method. Therefore, the slope evaluation method by aggregation method can improve efficiently the loss of slope information in according to the variation of resolution in water resource area such as rainfall-runoff model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3D
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• pp.373-379
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• 2009

Cost estimation in the early phase enables government to plan public budgeting more efficiently by providing information about construction cost. However, cost estimation in the early phase is difficult to predict because only a little information can be utilized. The cost estimation method now being used by the government is calculated by length of the road multiplied by unit cost per length and shows high error rate because it cannot reflect the unique characteristics of each project. As the project is being proceeded, level of available information also changed. So, reflecting available information of a project is important. This paper divided early phase into two parts : planning phase and early design phase, and developed cost estimation model considering level of available information of each phase. Total 143 cases are utilized to find influencing variables and develop cost estimation model and model validation is done by adopting required accuracy level. This cost estimation model reflecting level of available information can be applied to public budgeting, feasibility test, and comparison between routes.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.7-22
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• 2023

In January 2022, a new legislation was enforced to enhance the safety of underground construction. Consequently, a comprehensive assessment of underground safety is now an integral part of the planning process, including an evaluation of its impact. Ensuring the stability of temporary retaining walls during underground excavation has become paramount, prompting a heightened focus on the assessment of underground safety. This study delves into the analysis of the Multi-axis Flat Continuous Soil Cement Wall retaining wall (MFS) construction method. This method facilitates the expansion of wall thickness in the ground and provides flexibility in selecting and spacing H-piles. Through laboratory model tests, we scrutinized the load-displacement behavior of the wall, varying the H-pile installation intervals using the MFS method. Additionally, a 3-dimensional numerical analysis was conducted to explore the influence of H-pile installation intervals and sizes on the load for different thicknesses of the MFS retaining wall. The displacement analysis yielded the calculation of the height of the arching effect acting on the wall. To further our understanding, a design method was introduced, quantitatively analyzing the results of axial force and shear force acting on the wall. This involved applying the maximum arching height, calculated by the MFS method, to the existing member force review method. The axial force and shear force, contingent on the H-pile installation interval and size applied to the MFS retaining wall, demonstrated a reduction effect ranging from 24.6% to 62.9%.

• Journal of Internet of Things and Convergence
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• v.10 no.1
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• pp.29-37
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• 2024

The purpose of this study is to investigate the impact of education applying the Havruta learning method in fundamentals nursing classes for nursing students on problem-solving ability, self-directed learning ability, critical thinking disposition, and learning commitment. One-group pretest-posttest design was used. Nursing students received training applying the Havruta learning method for 6 weeks (12 hours) in fundamentals nursing classes. The study was conducted from September 18 to November 6, 2023. Data were analyzed using SPSS/WIN 28.0 with mean, standard deviation, and paired samples t-test. problem-solving ability (t=4.52, p<.001), self-directed learning ability(t=-4.61, p<.001), critical thinking disposition(t=-4.10, p<.001) significantly increased before and after the 6-week Havruta learning method training for nursing students. However, there was no statistically significant difference in learning commitment (t=-0.28, p=.782). The Havruta learning method is an effective nursing education tool for improving problem-solving ability, self-directed learning ability, and critical thinking disposition. The results of this study can serve as basic data for nursing professors when planning teaching and learning strategies using Havruta. Research will be needed to utilize the Havruta learning method in various classes and evaluate its effectiveness.