• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.111-119
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• 2019

The purpose of this study is to investigate the shear strength of reinforced concrete beam according to beam section size and shear reinforcement ratio. A total of nine specimens were tested and designed concrete compressive strength is 24 MPa. The main variables are shear reinforcement ratio and beam section size fixed with shear span to depth ratio (a/d = 2.5), the tensile reinforcement ratio (${\rho}=0.013$) and width to depth ratio (h/b = 1.5). The test specimens were divided into three series of S1 ($225{\times}338mm$), S2 ($270{\times}405mm$) and S3 ($315{\times}473mm$), respectively. The experimental results show that all specimens represent diagonal tensile failure. For $S^*-1$ specimens (d/s=0), the shear strength decreased by 33% and 46% with increasing the beam effective depth, 26% and 33% for $S^*-2$ specimens (d/s=1.5) and 16% and 20% for $S^*-3$ specimens (d/s=2.0) respectively. As the shear reinforcement ratio increases, the decrease range in shear strength decreases. In other words, this means that as the shear reinforcement ratio increases, the size effect of concrete decreases. In the S1 series, the shear strength increased by 39% and 41% as the shear reinforcement ratio increased, 54% and 76% in the S2 series and 66% and 100% in the S3 series, respectively. As the effective depth of beam increases, the increase range of shear strength increases. This means that the effect of shear reinforcement increases as the beam effective depth increases. As a result of comparing experimental values with theoretical values by standard equation and proposed equation, the ratio by Zsutty and Bazant's equation is 1.30 ~ 1.36 and the ratio by KBC1 and KBC2 is 1.55~.163, respectively. Therefore, Zsutty and Bazant's proposed equation is more likely to reflect the experimental data. The current standard for shear reinforcement ratio (i.e., $S_{max}=d/2$) is expected to be somewhat relaxed because the ratio of experimental values to theoretical values was found to be 1.01 ~ 1.44 for most specimens.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.297-304
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• 2021

This study aims not only to access the visual thought-oriented approach that has been implemented in established art therapy and education but also to integrate language education and therapeutic approach to support the development of school-age children. Thus, text mining technique was applied to search for areas where different areas of language and art can be integrated. This research was conducted in accordance with the procedure of basic research, preliminary DB construction, text screening, DB pre-processing and confirmation, stop-words removing, text mining analysis and the deduction about the convergent areas. These results demonstrated that this study draws convergence areas related to regional, communication, and learning functions, areas related to problem solving and sensory organs, areas related to art and intelligence, areas related to information and communication, areas related to home and disability, topics, conceptualization, peer-related areas, integration, reorganization, attitudes. In conclusion, this study is meaningful in that it established a framework for designing an activity-centered convergence program of art and language in the future and attempted a holistic approach to support child development.

• Journal of Convergence for Information Technology
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• v.11 no.2
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• pp.219-228
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• 2021

The purpose of this study was to examine the experiences of participation in the educational community through cooperative relationships between early childhood teachers and researchers in early childhood mathematics education using storytelling, and to find out the meaning of those experiences. Reputable researchers began with the formation of the educational community on March 14, 2016, and continued until July 26, 2016, and collected transcripts of discussions of educational community meetings, reflective journal data of teachers and researchers, and transcript of individual interviews by teachers. As a result of the study, first, the experience of participating in the educational community in early childhood mathematics education using storytelling shared personal mathematics experiences and mathematical situations, understood and learned mathematics content knowledge through sharing, and communicated through the educational community. Second, looking at the meaning of the experience of participating in the early childhood mathematics education educational community using storytelling, learn together through mathematical errors and learn the direction of better instruction through sharing. Grown up as a teacher who enjoys the mathematics exploration process, and promoted joint practice through cooperation in early childhood mathematics education using storytelling.

• Structural Engineering and Mechanics
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• v.76 no.6
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• pp.687-708
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• 2020

Openings in steel plate shear walls (SPSWs) are usually used for decorative designs, crossing locations of multiple utilities and/or structural objectives. However, earlier studies showed that generating an opening in an SPSW has a negative effect on the cyclic performance of the SPSW. Therefore, this study proposes tripling or doubling the steel-sheet-plate (SSP) layer and stiffening the opening of the SPSW to provide a solution to undesirable opening effects, improve the SPSW performance and provide the infill option of potential strengthening measures after the construction stage. The study aims to investigate the impact of SSP doubling with a stiffened opening on the cyclic behaviour, expand the essential data required by structural designers and quantify the SPSW performance factors. Validated numerical models were adopted to identify the influence of the chosen parameters on the cyclic capacity, energy dissipation, ductility, seismic performance factors (SPF) and stiffness of the suggested method. A finite Element (FE) analysis was performed via Abaqus/CAE software on half-scale single-story models of SPSWs exposed to cyclic loading. The key parameters included the number of SSP layers, the opening size ratios corresponding to the net width of the SSP, and the opening shape. The findings showed that the proposed assembly method found a negligible influence in the shear capacity with opening sizes of 10, 15, 20%. However, a deterioration in the wall strength was observed for openings with sizes of 25% and 30%. The circular opening is preferable compared with the square opening. Moreover, for all the models, the average value of the obtained ductility did not show substantial changes and the ultimate shear resistance was achieved after reaching a drift ratio of 4.36%. Additionally, the equivalent sectional area of the SSP in the twin and triple configuration of the SPSWs demonstrated approximately similar results. Compared with the single SSP layer, the proposed configuration of the twin SSP layer with a stiffened opening suggest to more sufficiency create SSP openings in the SPSW compared to that of other configurations. Finally, a tabular SPF quantification is exhibited for SPSWs with openings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.453-459
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• 2021

The system marginal price of electricity is the amount paid to all the generating units, which is an important decision-making factor for the construction and maintenance of an electrical power unit. In this paper, we suggest a long-term forecasting model for calculating the system marginal price based on prices of natural gas and oil. As most variables used in the analysis are nonstationary time series, the long run relationship among the variables should be examined by cointegration tests. The forecasting model is similar to an error correction model which consists of a long run cointegrating equation and another equation for short run dynamics. To mitigate the robustness issue arising from the relatively small data sample, this study employs various testing and estimating methods. Compared to previous studies, this paper considers multiple fuel prices in the forecasting model of system marginal price, and provides greater emphasis on the robustness of analysis. As none of the cointegrating relations associated with system marginal price, natural gas price and oil price are excluded, three error correction models are estimated. Considering the root mean squared error and mean absolute error, the model based on the cointegrating relation between system marginal price and natural gas price performs best in the out-of-sample forecast.

• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.2
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• pp.78-90
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• 2021

In order to construct a precision geoid, it has been diversified into land, sea, aviation, and satellite gravity measurement methods, and measurement technology has developed, making it possible to secure high-resolution, high-precision gravity data. The construction of precision geoids can be fast and conveniently decided through GNSS surveys without separate leveling, and since 2014, the National Geographic Information Institute has been developing a hybrid geoid model to improve the accuracy of height surveying based on GNSS. In this study, the results of the GNSS height measurement were compared and analyzed choosing existing public reference points to verify the GNSS height measurement of public surveys. Experiments are conducted with GNSS height measurements and analyzed precision for public reference points on coastal, border, and mountainous terrain presented as low-precision areas or expected-to-be low-precision in research reports. To verify the GNSS height measurement, the GNSS ellipsoid height of the surrounding integrated datum to be used as a base point for the GNSS height measurement at the public datum. Based on the checked integrated datum, the GNSS ellipsoid of the public datum was calculated, and the elevation was calculated using the KNGeoid18 model and compared with the results of the direct level measurement elevation. The analysis showed that the results of GNSS height measurement at public reference points in the coastal, border, and mountainous areas were satisfied with the accuracy of public level measurement in grades 3 and 4. Through this study, GNSS level measurement can be used more efficiently than existing direct level measurements depending on the height accuracy required by users, and KNGeoids 18 can also be used in various fields such as autonomous vehicles and unmanned aerial vehicles.

• 한국사회정책
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• v.24 no.4
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• pp.3-29
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• 2017

The study checked whether the trade-off relationship between the home ownerhip and welfare by Kemeny and Castles was still valid in four welfare regimes, and analysed the factors of change and stability on rate of home ownership between social democratic states and southern european states. Based on the results of the study, the relationship between housing ownership and public expenditure was confirmed only in the liberal welfare regime and in the conservative welfare regime, as evidenced by the 2014 data collection. Second, social democratic states have dramatically increased housing mortgage loans and showed signs of housing commodification but southern european states have showed pre commodification of housing, maintained comparatively whole home ownership and low mortgage loans. Third, social democratic states has resulted in a rise in housing demand and housing prices, through reduced new housing and social rented housing construction, home owenership friendly taxation and generous lending policies, but southern european states have maintained a stable housing demand and housing prices thanks to the rich housing stocks, extended family, self provision and self promotion by close relatives, and intergenerational inheritance and transfers of housing. Although sequence of the equity ownership and welfare are still unclear, it is not a rational alternatives to induce housing ownership through large mortgage loans.

• Journal of the Korean GEO-environmental Society
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• v.22 no.3
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• pp.37-43
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• 2021

This study aimed to calculate the amount of change in soil carbon due to changes in land cover. Among the various soil carbon models, the InVEST Carbon Storage and Sequestration module was used. LULC is one of the leading factors affecting soil carbon. Therefore, this study compared the total amount of soil carbon due to changes in LULC in 2000 and 2010 across the Republic of Korea, and calculated the changes in each administrative district (city). Changes in LULC in Korea were mainly due to the increase in developed and dry areas and the decrease in grassland, indicating changes in soil carbon. The total amount of soil carbon changes in South Korea has been reduced by 11.48 (millions) in 10 years. The amount of soil carbon by administrative region decreased in most cities and provinces, but Jeju Island, in exception, showed an increase in soil carbon. Among the cities and provinces except Jeju Island, Seoul showed the smallest decrease, with a decrease of 0.033 (million t). On the contrary, the largest number of attempts to decrease was to Gyeongsangbuk-do, which saw a total decrease of 2.893 (million t). Jeju Island is the only soil carbon-increasing area with an increase of 0.547 (millions) and the agricultural area has increased 2.1 times in 10 years. In the case of soil carbon, the construction of ground observation data at the national unit is insufficient, and verification will need to be carried out through linked analysis using multiple models in the future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.9-18
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• 2021

Recently, the rapid proliferation, introduction, and application of the fourth industrial revolution technology has emerged as a trend in the construction market. Building Information Model (BIM) technology is a multidimensional information system that forms the basis of the fourth industrial revolution technology. The river sector utilizing this information-based system is also being actively reviewed, for example, the current measures for maintenance. In recent years, active research and current work should be done to reflect the need for river experts to introduce BIM into the river field. In addition, the development of tools and support software for establishing various information systems is essential for the activation of facility maintenance information systems reflecting advanced technology and to establish and operate management plans. A study on the maintenance of river facilities involves using existing drawings to build a three-dimensional (3D) information model, check the damage utilizing it, and inform it, and utilize it as the data for maintenance reinforcement. This study involved determining a method to build a river facility without the existing information system and using the property maintenance information with 3D modeling to provide a more effective and highly utilized management plan to check maintenance operations and manage damages.

• Journal of Korean Society of Rural Planning
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• v.27 no.1
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• pp.57-70
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• 2021

The degree of benefits of living services related to the quality of life can solve the depopulation problem, and it is necessary to be able to quantitatively analyze problems related to the quality of life in rural areas in order to cope with the rural depopulation. The purpose of this study was to develop the assessment model of a village-level rural living service that reflects the regional characteristics of rural villages to evaluate the level of rural living services for response rural depopulation. Based on the review of previous related studies, the evaluation index was composed of seven sectors of education, health, welfare, culture, environment, safety, and convenience, and the assessment model of a rural living service was established. This model was evaluated through a sample survey of 90 villages in Nonsan-si, Seongju-gun, and Pyeongchang-gun. As a result of the rural life services evaluation by Si and Gun, Seongju-gun, which is affected by nearby large cities, has the largest variation by village level and is assessed at a lower level overall than other Si and Gun. As a result of the rural life services evaluation by 7 sectors, in the case of health and welfare, low scores were shown in the assessment model, but the level of residents' satisfaction was mid-level. In particular, in the case of Seongju-gun, there were significant differences in the assessment model and the survey results of the level of residents' satisfaction in the health and welfare sectors due to the influence of nearby large cities. As a result of analyzing the number of villages corresponding to the top 30% and the bottom 30% of the evaluation results for each sector, it was analyzed that the villages with the highest evaluation results in Pyeongchang-gun in both the assessment model and the level of residents' satisfaction. It implies that quantitative analysis of data based index and accessibility as well as level satisfaction of residents are necessary.