• The Journal of the Convergence on Culture Technology
• /
• v.8 no.6
• /
• pp.727-732
• /
• 2022

Applying the calculated cross-sectional reduction due to the corroded rebar investigated in the field to the numerical analysis model, the damage pattern and delamination of concrete in the field showed a tendency relatively similar to the numerical analysis results. It was analyzed that when the expansion pressure due to corrosion of the reinforcing bar is greater than the tensile stress of the concrete, cracks are generated and the concrete cover can be fracture. As a result of this study, the correlation between the corrosion rate of reinforcing bars and the crack occurrence of the concrete cover of the subway box structure was verified based on the numerical analysis and field test results. To prevent rebar corrosion, the corrosion rate can be reduced by applying rust prevention to the reinforcing bar and changing the material. In the case of exposed to a corrosive environment, the tensile strength of the concrete is improved by adjusting the concrete compressive strength to secure durability against the expansion pressure caused by the corroded rebar.

• Journal of the Korean Geosynthetics Society
• /
• v.21 no.2
• /
• pp.11-19
• /
• 2022

In this paper, we propose a GoogleNet transfer learning and CNN-LSTM combination method to improve the time-series prediction performance for crack detection using crack data captured inside the sewer pipes. LSTM can solve the long-term dependency problem of CNN, so spatial and temporal characteristics can be considered at the same time. The predictive performance of the proposed method is excellent in all test variables as a result of comparing the RMSE(Root Mean Square Error) for time series sections using the crack data inside the sewer pipe. In addition, as a result of examining the prediction performance at the time of data generation, the proposed method was verified that it is effective in predicting crack detection by comparing with the existing CNN-only model. If the proposed method and experimental results obtained through this study are utilized, it can be applied in various fields such as the environment and humanities where time series data occurs frequently as well as crack data of concrete structures.

• Journal of The Korean Society of Integrative Medicine
• /
• v.11 no.1
• /
• pp.141-148
• /
• 2023

Purpose : This study examined the relationship between suicidal thoughts, hand grip strength, socioeconomic status, educational level, and disease occurrence. Methods : Korean national health and nutrition examination survey 2017 were used in this study. 5,449 were analysed. For comparison between groups, cross-tabulation analysis and mean comparison were performed. Logistic regression analysis were performed to analyze the influencing factors between grip strength and suicidal ideation. Results : Our results are consistent with the literature on the importance of socioeconomic status in health. The lower the level of education, the higher the suicidal thoughts. Being single or divorced was also significantly associated with suicidal ideation. Moreover, a lower income level was significantly associated with a higher suicide intention. Furthermore, older ages, lower educational levels, and lower income were significantly associated with a higher odds ratio of suicidal thoughts. Interestingly, suicidal thoughts were significantly lower among non-smokers. In contrast, suicide intention did not differ significantly according to gender, age, monthly drinking habit, aerobic physical activity, and disease occurrence. Suicidal thoughts decreased as grip strength increased and this was statistically significant. Socioeconomic status, disease occurrence, and handgrip strength level affected the security of an individual's livelihood and were significant risk factors for suicidal thoughts. These associations remained significant in multiple logistic regression even after controlling for all covariates. Conclusion : Future prevention intervention efforts to reduce suicide risks should consider handgrip strength. Studies to explore the possible proximal risk factors and mediators between handgrip strength and suicidal thoughts are also warranted.

• Journal of Korean Society of Rural Planning
• /
• v.28 no.4
• /
• pp.19-29
• /
• 2022

This study aimed to estimate the impervious area rate by rural water districts in 2009 and 2021 and analyze the changes. From the EGIS(Environmental Geographic Information Service) land cover maps, the impervious areas were defined as residential, commercial, industrial, culture·sports·recreational, traffic, public facilities, and greenhouses of land cover classes. For 496 rural water districts excluding the border area with North Korea, the nationwide impervious area rate increased from 5.96% in 2009 to 7.50% in 2021. The average of the top 50 rural water districts increased from 23.4% in 2009 to 27.1% in 2021. E ven for the bottom 50 rural water districts, the average impervious area rate rose from 1.12% in 2009 to 1.40% in 2021. Rural water districts with a high impervious area rate are mainly distributed in metro cities and industrial areas. The contraries are primarily found in Gangwon, Gyeongsang, and Jeolla regions covered with forests and farmlands. Notably, the impervious area rate changed more in the neighboring rural water districts than in large cities, and the rate kept increasing slightly even in rural areas with a low impervious area rate. The findings of this study will help prepare a reasonable alternative for managing the impermeable surface of rural areas for safe and sound rural water cycle.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.3
• /
• pp.277-282
• /
• 2022

The sleeper floating track (STEDEF) in this study was a track type in which a very soft resilience pad was installed under a relatively thin concrete sleeper (RC Block). Therefore it was expected that the resilience pad could affect the estimation results of the concrete strength. In this study, field applicability evaluation was performed to apply the rebound hardness test method, which was a general method for estimating the compressive strength of concrete in civil structures, to concrete sleepers of railway tracks. In order to analyze the strength estimation technique of concrete sleepers reflecting the characteristics of track structures different from those of civil structures, the parameter experiments that could affect the strength estimation results of concrete sleepers in a serviced line were performed. As a result of the study, the appropriate hitting position was suggested considering the shape of the concrete sleeper, and the difference in strength estimation results according to the condition of the concrete sleeper and supporting conditions was derived.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.4
• /
• pp.633-638
• /
• 2023

In this study, the effect of the change in cable tension on the track irregularity of railway ballasted track on a railway steel composite bridge was analyzed. As a result of comparing design and analysis results for cable tension, a difference of less than 3% was found, and analysis modeling was analyzed to reflect the design conditions well. In addition, the adequacy of the analysis modeling was demonstrated by comparing the field measurement results with the analysed cable tension. By considering the change in cable tension as a variable, the track irregularity of the railway steel composite bridge was analyzed. As a result of the analysis, it was analyzed that the total and one-sided cable tension change had a direct effect on the vertical irregularity among the track irregularity items. In addition, it was found that the change in track irregularity occurred in the section close to the cable position. It was analyzed that the change in cable tension had a more direct effect on track irregularity that had a direct correlation with the vertical direction rather than the lateral direction.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.4
• /
• pp.593-599
• /
• 2023

There is risk of derailment due to various factors such as vehicle-track load imbalance in curved parts, so urban railways install and operate derailing prevent guard rails. The angle-type derailing prevent guard rail is composed of various parts including the guard angle. Even if derailment does not occur, various damages occur in the components, so continuous maintenance is required. Through the damage status analysis, the components of the angle-type derailing prevent guard rail with high damage frequency were classified, and conditions for the occurrence of various damages were investigated. In addition, a numerical analysis using a precise 3D numerical model was performed to analyze the cause of the damage analytically. In order to analytically simulate the derailment situation, the static ultimate load condition was applied, and the actual drawing of the angle-type derailing prevent guard rails, rails, and wheels was used for modeling. By analyzing the results of the damage status investigation and finite element analysis, we tried to investigate the damage of the components.

• Proceedings of the KSR Conference
• /
• 2009.05a
• /
• pp.1254-1268
• /
• 2009

In 1998, because of the economic crisis called IMF Crisis in Korea, Kyungbu high speed railway project could run by modifying the original plan to open it as a 1st phase only by utilizing the existing railway lines from Seoul to Siheung and the other one from Daegu to Pusan. The modified plan includes that the line from Daegu to Pusan will be constructed as a second phase in next time. Starting railway operation with the changed plan, the combined application operation of high speed rail, passenger rail and freight rail was caused partly from Seoul to Siheung to run into capital area. As a result, the opinion for additional railway line construction is insisted continuously because the operation volume of passenger rail was forced to be reduced, the service quality of it was decreased and it became difficult to add new high speed services. Moreover, with regard to Honam high speed rail, the new construction plan of station in Kangnam metro area as a basement station for starting from Suseo was changed to the plan of turning out at Osong because of the economic effectiveness and this kept resident people in Kangnam metro area and southern Kyungki area unable to get the opportunity of high speed rail service benefit. After beginning of Kyungbu high speed railway operation, national transportation system developments are focused on high speed rail, and when the second phase construction of Kyungbu high speed rail, beginning operation of Kyungjeon line, Jeolla line double track construction, Honam high speed rail in 2014, is completed, the demand for high speed rail will be increased and it is unavoidable to make Kwangmyung station as a basement station and to reduce the number of passenger rail operation. At this moment, it is valuable to consider adding the railway line capacity in capital area to improve the transferring service for citizen who live in area without Kyungbu high speed rail station and to expand the service area from Kangbuk to Kangnam and southern Kyungki area. Accordingly, in this paper, the effective rail operation method, facility plan and the other issue to be reviewed for increasing capital high speed railway lines will be mentioned.

• Journal of Digital Convergence
• /
• v.11 no.8
• /
• pp.53-64
• /
• 2013

This study was conducted from the time when discussion of improvement and keeping heavy taxation on multiple home owners was began, experts who may express professional opinion such as realtors, tax accountants and revenue officers were picked up besides the direct interested parties such as single and multiple home owners. This study collected their various opinions regarding whether keeping the heavy taxation system on multiple home owners or not and the effect of it. As a result of the survey, people living in Seoul who owned more houses showed higher awareness about heavy taxation on multiple home owners, and people agreed more about abolishing the heavy taxation when they own more homes. From this study, it was found out that different recognition about heavier transfer income tax on multiple home owners of each person concerned and necessity of rearranging this uncertain condition of temporary regulation in the future. The tax law should be improved to supply clear policy signals to the market for recovery of housing transactions and supply expansion of jeonsei to monthly rental housing and managing of taxation policy which reflects taxpayers' opinion may correspond to more effective and fair taxation principle.

• Journal of the Korean Society for Railway
• /
• v.16 no.3
• /
• pp.189-195
• /
• 2013

Recent trains have broadband train communication networks to improve train operation safety and to provide passengers with multimedia services. Compared to glass optical fiber, plastic optical fiber (POF) has a large diameter; it also provides the good durability and maintainability necessary to railway applications. This paper suggests an All-IP broadband train communication network that connects all devices in the train through a POF interface. Performance tests according to Korean railroad standards shows that this POF interface is usable in the range of vibration and temperature conditions encountered in trains. A dedicated Layer-2 switch with the POF interface is developed for the construction of the All-IP train communication network. A prototype 1Gbps train communication network was set up in a trial-run of train on a metro line using the developed Layer-2 switch and POF. On-track tests indicated the feasibility of the POF train communication network. POF has an additional advantage of economic feasibility, and it is expected to start a trend toward broadband train communication networks using POF.