• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.679-697
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• 2022

Having an awareness of the ongoing conception of Honam-Jeju, Korea-Japan, and Korea-China subsea tunnels for accommodating the railway, this paper investigates immersion tube tunnel technology, one of the underwater tunnel construction methods. This paper analyses the current status of immersed tube tunnels according to their location and function. This paper summarises the dredging methods and briefly introduces the muck disposal facility. Also introduced are the case studies where measures were taken to mitigate the impact of dredging on the surrounding marine environment. This paper also explains how the tunnel elements are connected underwater using an immersion joint. This paper classifies the foundation methods into bedding and ground improvement methods and provides summaries, including their environmental impact associated with drill cuttings and cementitious binders.

• Journal of Ocean Engineering and Technology
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• v.33 no.5
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• pp.435-446
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• 2019

Because offshore structures are affected by various environmental loads, the risk of damage is high. As a result of ever-changing ocean environmental loads, damage to offshore structures is expected to differ from year to year. However, in previous studies, it was assumed that a relatively short period of load acts repeatedly during the design life of a structure. In this study, the residual life of an offshore wind turbine support structure was evaluated in consideration of the timing uncertainty of the ocean environmental load. Sampling points for the wind velocity, wave height, and wave period were generated using a central composites design, and a transfer function was constructed from the numerical analysis results. A simulation was performed using the joint probability model of ocean environmental loads. The stress time history was calculated by entering the load samples generated by the simulation into the transfer function. The damage to the structure was calculated using the rain-flow counting method, Goodman equation, Miner's rule, and S-N curve. The results confirmed that the wind speed generated at a specific time could not represent the wind speed that could occur during the design life of the structure.

• Tunnel and Underground Space
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• v.31 no.4
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• pp.211-220
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• 2021

Tunnel collapse often occurs during deep underground tunneling (> 40 m depth) in South Korea. Natural cavities as well as water supply pipes, sewer pipes, electric power cables, artificial cavities created by subway construction are complexly distributed in the artificial ground in the shallow depths of the urban area. For deep tunnel excavation, it is necessary to understand the properties of the ground which is characterized by porous elements and various geological structures, and their influence on the stability of the ground. This study analyzed geological factors for risk assessment in deep excavation in South Korea based on domestic and overseas case study. As a result, a total of 7 categories and 38 factors were derived. Factors with high weights were fault and fault clay, differential stress, rock type, groundwater and mud inrush, uniaxial compressive strength, cross-sectional area of tunnel, overburden thickness, karst and valley terrain, fold, limestone alternation, fluctuation of groundwater table, tunnel depth, dyke, RQD, joint characteristics, anisotropy, rockburst and so forth.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.3
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• pp.262-271
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• 2022

The purpose of this study is to investigate the status of admission and employment in fisheries high schools (FHS) and to consider ways to revitalize FHS through substantialization. The recruitment rate of new students in FHS decreased from 97.4% in 2016 to 83.2% in 2020. The aging training ship that FHS needs to improve most urgently is being jointly used by FHS across the country, and the construction of a joint training ship managed by the Korea Institute of Maritime and Fisheries Technology is being promoted. The average employment rate for FHS by year was 40.2-59.4%, and the fisheries-related employment rate was low at 31.0-38.9%. On the other hand, the acquisition rate of certificate of competence was 37.5-52.0%, and the rate of employment on board of those who obtained the certificate of competence was 42.9-59.8%. In order to secure new students and improve the recruitment rate, we operate experiential classrooms that reflect the characteristics of training ships and departments and conduct public relations activities using sns, publicity video ucc, YouTube, etc. It will be necessary to expand opportunities for fisheries-related vocational experience through active career exploration and elective courses in the FHS credit system. Finally, it is judged that fisheries related government agencies, industries and local governments need to improve their awareness of FHS and plan to support fisheries manpower nurturing in order to attempt the vitalization of FHS.

• Journal of the Korean Society for Library and Information Science
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• v.57 no.1
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• pp.161-182
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• 2023

In the recent cataloging environment, the function of authority data is becoming more important. In Korea, a pilot project for sharing and joint use of the national authority data has been promoted since 2019, and a plan to automatically construct retrospective authority data using national authorities is in progress. This study aims to (1) analyze the results of the pilot project for retrospective authority data jointly promoted by the National Library of Korea and KERIS in 2019, (2) explore methodological limitations and problems in the process, and (3) derive policy proposals for constructing authority data more efficiently. To this end, a university library participating in the pilot project was investigated as a case study. Based on it, the automatic generation rate and accuracy of authority data, and errors and omissions cases and causes were analyzed in detail. As a results of the study, it was found that the quality of union catalogs and bibliographic records had a great influence on automatically constructing authority data, and supplementary methods were needed to minimize these limitations.

• Journal of Urban Science
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• v.11 no.2
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• pp.25-30
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• 2022

Resin Transfer Molding FRP (RTM FRP) is a fiber reinforced polymeric plastic which is manufactured by applying pressure to fibers, injecting resin into a mold, and then impregnating it. RTM FRP is a new construction material suitable for producing non-continuum structural elements such as sole plate because it has excellent strength and can produce many members in a short time. In this study, experiments were conducted to estimate the capacity of the bolted connection of RTM FRP. First, a tensile test was conducted to confirm the mechanical properties such as the tensile strength of the RTM FRP to be used for the bolted connection experiments. In addition, experiments were conducted on the bolted connection with the thickness of the RTM FRP and the edge distance of the bolt as variables. In the first experiment, F4.8 bolts were used, and shear failure of the bolt occurred before the RTM FRPs were failed. The F4.8 bolt is a general structural bolts used for the sole plate of a bridge bearing, and it was confirmed that the RTM FRP has a higher bold bearing strength than the shear strength of a F4.8 bolt. In the second experiment, G12.9 bolts were used, and shear failure of the bolt and bearing failure of the RTM FRP occurred simultaneously. In addition, as the thickness of the RTM FRP and the edge length of the bolt increased, the strength of the joint increased. When analogized with the bearing fracture equation of steel plate, the bolted connection of RTM FRP showed a bearing strength coefficient of 0.420 to 0.549 compared to the tensile strength, and it is considered that further research is needed.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.3
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• pp.129-137
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• 2023

This study presents a dry precast concrete (PC) beam-column connection, and its target seismic performance level is set to be emulative to the reinforced concrete (RC) intermediate moment resisting frame system specified in ACI 318 and ASCE 7. The key features include self-sustaining ability during construction with the dry mechanical splicing method, enabling emulative connection performances and better constructability. Test specimens with code-compliant seismic details were fabricated and tested under reversed cyclic loading, which included a PC beam-column connection specimen with dry connections and an RC control specimen. The test results showed that all the specimens failed in a similar failure mode due to plastic deformations in beam members, while the hysteretic response curve of the PC specimen showed comparable and emulative performances compared to the RC specimen. Seismic performance evaluation was quantitatively addressed, and on this basis, it confirmed that the presented system can fully satisfy all the required performance for the intermediate RC moment resisting frame.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.37-47
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• 2010

To improve the grout penetration characteristics, a vibratory grout injection technique was adopted in this study. It is a technique of grout injection in which an oscillating pressure is added to the steady-state pressure as an injection pressure. By applying the vibration during grout injection, cement particles will become less adhesive and the clogging tendency will be decreased. A series of pilot-scale chamber tests were performed to verify the enhancement of the groutability by applying the vibratory grout injection; assessment on the change of the lumped parameter $\theta$ which represents a barometer of clogging phenomenon was made. Moreover, the effect of vibratory grout injection through the joint was also investigated using artificially made rock joints. Experimental results as well as analytical results show that the grout penetration depth can be substantially improved by vibratory grouting. Moreover, it was found that enhancement of the permeation grouting due to vibratory injection is more dominant at grouting pressure less than 400 kPa.

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.149-160
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• 2007

Six prototype field tests (five 1/8 and one 1/2 scale tests) have been conducted in order to determine the uplift resistance of deep foundation for transmission line structures. Test sites, located in the city of Eumseng in Choongbuk province, are classified as gneiss. These test results reveal failures not along the foundation-rock interface but either along the damaged surrounding rock mass caused by excavation or along the pre-existing rock joint. Test results also show the uplift resistance which is 20 $\sim$ 30% higher than the current design strength of side friction. In addition to fold tests, four concrete core samples between the liner plate and the surrounding rock mass have been obtained from the existing transmission foundations to study the effect of the liner plate which is installed prior to placing concrete. The compressive strength of these concrete core samples shows 63 $\sim$ 72% of the strength at the time of foundation construction. Side frictional resistance based on such less compacted concrete reaches satisfying uplift design strength.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.2
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• pp.89-102
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• 2023

The purpose of this study is to examine what are the important variables for information security compliance and whether the information security investment by the industry is different. To comply with the information security policies, the organization must establish measures to prevent or resolve information security incidents. This research process consists of four stages, and the analysis method was conducted with the categorical regression analysis and the correspondence analysis. The first analysis analyzed the independent variables that affect security regulations compliance. The rest of the analysis was conducted by industry in the order of security compliance regulations, manpower investment, and budget investment. As a result of the first analysis, this had positive effects on an organization and personal information protection awareness, joint operation organization of information protection, manpower and budget investment, corporate size, and industry. The correspondence analysis was conducted from the second analysis to the fourth analysis and it analyzed the differences in information security investment by industry. The second analysis showed that the construction industry, science and technology industry, and finance industry have higher compliance with security regulations than other industries. The third analysis showed that the financial industry and the science and technology industry were higher than other industries. The last analysis showed that the financial industry was higher than other industries. The theoretical contribution of this study provided the basis for updating the information security theory. The practical contribution of this study requires government support to reduce information security deviations by industry.