• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.655-662
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• 2023

Big data research plays a role of supplementing existing social science research methods. If the survey and experimental methods are somewhat inaccurate because they mainly rely on recall memories, big data are more accurate because they are real-time records. Social science research so far, which mainly conducts sample research for reasons such as time and cost, but big data research analyzes almost total data. However, it is not easy to repeat and reproduce social research because the social atmosphere can change and the subjects of research are not the same. While social science research has a strong triangular structure of 'theory-method-data', big data analysis shows a weak theory, which is a serious problem. Because, without the theory as a scientific explanation logic, even if the research results are obtained, they cannot be properly interpreted or fully utilized. Therefore, in order for big data research to become a methodological innovation, I proposed big thinking along with researchers' efforts to create new theories(black boxes).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.243-250
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• 2009

The purpose of this study is to investigate several strategies that can be used to extend the span of conventional PSC girder bridge and to propose a systematic procedure to evaluate the effect of each strategy on the span. In the preceding companion paper, fundamental equations were derived which constitute the assessment graphs and a possible domain for the design. Quantitative evaluation for extension of the span follows here by adopting a sample PSC girder bridge. It apparently shows a number of advantages of the proposed scheme in finding out why and how each strategy contributes to the span extension and in suggesting further improvement for a longer span. The results imply that increasing the strength of a girder, the multistage prestressing with the secondary tendons prestressed before composite action with a deck, and Decked PSC girder are very effective among the strategies examined. It is expected that the span of the PSC girder bridge can be well extended up to 50 m to 70 m which corresponds to a span of the conventional box girder bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.89-98
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• 2006

In this study, the iron and aluminium electrode was put in marine clay which was taken from south coast in Korea to increase the undrained shear strength by inducing the densification and cementation between clay particles and precipitation which was developed by electrode decomposition. For raising the cementation rate and reducing treatment time, high electric current( 2.5A) was applied in each electrode at semi-pilot scale soil box with marine clay. After the tests, the undrained shear strength was measured at designated points using cone penetration test device and sampling was conducted simultaneously in order to measure water content, pH and electric conductivity which would be the key for configuring the cementation effects indirectly. The iron electrode decomposition test results show that the water content adjacent to anode section decreased in 35% and increased in 13% at cathode section. The measured shear strength however, was increased considerably comparing to initial shear strength because of cementation effect between iron ions and soil particles. In case of aluminium electrode decomposition test, the distribution of measured shear strength and degree of improvement were more homogeneous than iron electrode decomposition test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.447-456
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• 2009

The design comparison and flexural reliability analysis of continuous span composite plate girder bridges are performed. The girders are designed by the methods of allowable stress design (ASD) and load and resistance factor design (LRFD). For the LRFD design, the design specification under development mainly by KBRC, based on AASHTO-LRFD specification in case of steel structures, is applied with the newly proposed design live load which has been developed by analyzing domestic traffic statistics from highways and local roads. For the ASD based design, the current KHBDC code with DB-24 and DL-24 live loads is used. The longest span length for the 3-span continuous bridges with span arrangement ratio of 4:5:4 is assumed to be from 30 m to 80 m. The amount of steel, performance ratios, and governing design factors for the sections designed by the ASD and LRFD methods are compared. In the reliability analysis for the flexural failure of the sections designed by two methods, the statistical properties on flexural resistance based on the yield strength statistics for over 16,000 domestic structural steel samples are applied.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.131-143
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• 2009

Under transverse earthquake shaking, arching action of bridge structures develops along the deck between the abutments thus providing the so-called deck resistance. The magnitude of the arching action for bridge structures is dependent on the number of spans, connection condition between deck and abutment or piers, and stiffness ratio between superstructure and substructure. In order to investigate the arching action effects for inelastic seismic responses of PSC Box bridges, seismic responses evaluated by pushover analysis, capacity spectrum analysis and nonlinear time-history analysis are compared for 18 example bridge structures with two types of span numbers (short bridge, SB and long bridge, LB), three types of pier height arrangement (regular, semi-regular and irregular) and three types of connection condition between superstructure and substructure (Type A, B, C). The arching action effects (reducing inelastic displacement and increasing resistance capacity) for short bridge (SB) is more significant than those for long bridge (LB). Semi-regular and irregular bridge structures have more significant arching action than regular bridges.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.303-311
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• 2010

There have been various forms of systems such as a digital speedometer or a black box etc. to meet the social requirement for reducing traffic accidents and safe driving. However that systems are based on after-accident vehicle data, there is limit to prevent the accident before. So in our previous research, by storing, analyzing the Vehicle-dynamic information coming from driver's behavior, we are developing the decision-device which could provide driver with Alerting-Information in real-time to enhance the driver's safety drive. but the performance valuation is not yet executed. Finally, this study developed positional recognition system by using the DGPS for pre-developed risky driving decision device. The result of test analyzed with the same that the aggregated vehicle dynamics data in DGPS and dangerous risky driving decision device. If the performance of risky driving decision device is verified by precisely positional recognition system, the risky driving management of vehicle would be effected.

• Structural Engineering and Mechanics
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• v.87 no.3
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• pp.221-229
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• 2023

Urbanization and industrialization have significantly increased the amount of solid waste produced in recent decades, posing considerable disposal problems and environmental burdens. The practice of waste utilization in concrete has gained popularity among construction practitioners and researchers for the efficient use of resources and the transition to the circular economy in construction. This study employed Lytag aggregate, an environmentally friendly pulverized fuel ash-based lightweight aggregate, as a substitute for natural coarse aggregate. At the same time, fly ash, an industrial by-product, was used as a partial substitute for cement. Concrete mix M20 was experimented with using fly ash and Lytag lightweight aggregate. The percentages of fly ash that make up the replacements were 5%, 10%, 15%, 20%, and 25%. The Compressive Strength (CS), Split Tensile Strength (STS), and deflection were discovered at these percentages after 56 days of testing. The concrete cube, cylinder, and beam specimens were examined in the explorations, as mentioned earlier. The results indicate that a 10% substitution of cement with fly ash and a replacement of coarse aggregate with Lytag lightweight aggregate produced concrete that performed well in terms of mechanical properties and deflection. The cementitious composites have varying characteristics as the environment changes. Therefore, understanding their mechanical properties are crucial for safety reasons. CS, STS, and deflection are the essential property of concrete. Machine learning (ML) approaches have been necessary to predict the CS of concrete. The Artificial Fish Swarm Optimization (AFSO), Particle Swarm Optimization (PSO), and Harmony Search (HS) algorithms were investigated for the prediction of outcomes. This work deftly explains the tremendous AFSO technique, which achieves the precise ideal values of the weights in the model to crown the mathematical modeling technique. This has been proved by the minimum, maximum, and sample median, and the first and third quartiles were used as the basis for a boxplot through the standardized method of showing the dataset. It graphically displays the quantitative value distribution of a field. The correlation matrix and confidence interval were represented graphically using the corrupt method.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.141-141
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• 2022

Drought is a global phenomenon that affects almost all landscapes and causes major damages. Due to non-linear nature of contributing factors, drought occurrence and its severity is characterized as stochastic in nature. Early warning of impending drought can aid in the development of drought mitigation strategies and measures. Thus, drought forecasting is crucial in the planning and management of water resource systems. The primary objective of this study is to make improvement is existing drought forecasting techniques. Therefore, we proposed an improved version of Seasonal Autoregressive Integrated Moving Average (SARIMA) model (MD-SARIMA) for reliable drought forecasting with three years lead time. In this study, we selected four watersheds of Han River basin in South Korea to validate the performance of MD-SARIMA model. The meteorological data from 8 rain gauge stations were collected for the period 1973-2016 and converted into watershed scale using Thiessen's polygon method. The Standardized Precipitation Index (SPI) was employed to represent the meteorological drought at seasonal (3-month) time scale. The performance of MD-SARIMA model was compared with existing models such as Seasonal Naive Bayes (SNB) model, Exponential Smoothing (ES) model, Trigonometric seasonality, Box-Cox transformation, ARMA errors, Trend and Seasonal components (TBATS) model, and SARIMA model. The results showed that all the models were able to forecast drought, but the performance of MD-SARIMA was robust then other statistical models with Wilmott Index (WI) = 0.86, Mean Absolute Error (MAE) = 0.66, and Root mean square error (RMSE) = 0.80 for 36 months lead time forecast. The outcomes of this study indicated that the MD-SARIMA model can be utilized for drought forecasting.

• The Journal of the Korea Contents Association
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• v.22 no.8
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• pp.170-179
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• 2022

In the theater-based movie industry, it is known that the diversity of movie consumption is hindered due to concentrated consumption. This study extends the existing discussions on the concentration of movie consumption in theaters to the concentration of online movie consumption. In addition, the study analyzes the impact of Covid-19 pandemic on movie consumption and the concentration thereof. For analysis, panel data for the period from 2012 through 2021 were collected by utilizing the box office data of the Korean Film Council. As a result of the analysis, it was found that the concentration of consumption by movie, country, and genre was higher in theaters than online. Further, the concentration of movie consumption has increased both in theaters and online until the outbreak of Covid-19 pandemic. During the Covid-19 pandemic period, the size of consumption has decreased both in theaters and online, while the concentration of consumption by movie online has increased. The result of this study implies a need for policy-level efforts to convert the trend of consumption concentration for long-term development of the movie industry with secured diversity of movie consumption, and for this, the study suggests that the use of online media would be useful.

• Journal of Leisure Studies
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• v.10 no.1
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• pp.1-27
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• 2012

According as the number of immigrants has dramatically increased since last 10years, immigrants' acculturation has become a matter of great importance to Korean society. This study reviews theories on acculturation in leisure studies, specifically marginality vs ethnicity theory, assimilation theory and it's extended models, Berry's box and it's extended models, and cross-cultural vs cultural perspectives on acculturation research. Moreover, It also examines domestic research trend for some aspects such as the number of publishing articles a year, major issues and theories applied to domestic studies, methodology and employees. Finally, some kinds of suggestion for domestic studies in the near future are discussed.