• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.79-89
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• 2024

Excessive inflow of groundwater during tunnel excavation not only affects the stability and constructability of the tunnel, but is also one of the main causes of ground settlement due to groundwater level drawdown. The most commonly applied measure against excessive groundwater inflow during tunnel excavation in soil or fractured zone is to reduce the ground permeability coefficient by injecting grout material. Generally, the grouting area is assumed to be same as the plastic zone that occurs during tunnel excavation, but injecting grout material in the area of plastic zone is appropriate only for reinforcement grouting. In order to determine the thickness of cutoff grouting, the amount of reduction in the water permeability coefficient due to the application of cutoff grouting must be considered. In this study, a method for estimating the range of cutoff grouting considering the reduction in permeability coefficient was mathematically derived and evaluated through computer numerical analysis.

• Journal of Intelligence and Information Systems
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• v.25 no.1
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• pp.1-19
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• 2019

Artificial intelligence (AI) is one of the main driving forces leading the Fourth Industrial Revolution. The technologies associated with AI have already shown superior abilities that are equal to or better than people in many fields including image and speech recognition. Particularly, many efforts have been actively given to identify the current technology trends and analyze development directions of it, because AI technologies can be utilized in a wide range of fields including medical, financial, manufacturing, service, and education fields. Major platforms that can develop complex AI algorithms for learning, reasoning, and recognition have been open to the public as open source projects. As a result, technologies and services that utilize them have increased rapidly. It has been confirmed as one of the major reasons for the fast development of AI technologies. Additionally, the spread of the technology is greatly in debt to open source software, developed by major global companies, supporting natural language recognition, speech recognition, and image recognition. Therefore, this study aimed to identify the practical trend of AI technology development by analyzing OSS projects associated with AI, which have been developed by the online collaboration of many parties. This study searched and collected a list of major projects related to AI, which were generated from 2000 to July 2018 on Github. This study confirmed the development trends of major technologies in detail by applying text mining technique targeting topic information, which indicates the characteristics of the collected projects and technical fields. The results of the analysis showed that the number of software development projects by year was less than 100 projects per year until 2013. However, it increased to 229 projects in 2014 and 597 projects in 2015. Particularly, the number of open source projects related to AI increased rapidly in 2016 (2,559 OSS projects). It was confirmed that the number of projects initiated in 2017 was 14,213, which is almost four-folds of the number of total projects generated from 2009 to 2016 (3,555 projects). The number of projects initiated from Jan to Jul 2018 was 8,737. The development trend of AI-related technologies was evaluated by dividing the study period into three phases. The appearance frequency of topics indicate the technology trends of AI-related OSS projects. The results showed that the natural language processing technology has continued to be at the top in all years. It implied that OSS had been developed continuously. Until 2015, Python, C ++, and Java, programming languages, were listed as the top ten frequently appeared topics. However, after 2016, programming languages other than Python disappeared from the top ten topics. Instead of them, platforms supporting the development of AI algorithms, such as TensorFlow and Keras, are showing high appearance frequency. Additionally, reinforcement learning algorithms and convolutional neural networks, which have been used in various fields, were frequently appeared topics. The results of topic network analysis showed that the most important topics of degree centrality were similar to those of appearance frequency. The main difference was that visualization and medical imaging topics were found at the top of the list, although they were not in the top of the list from 2009 to 2012. The results indicated that OSS was developed in the medical field in order to utilize the AI technology. Moreover, although the computer vision was in the top 10 of the appearance frequency list from 2013 to 2015, they were not in the top 10 of the degree centrality. The topics at the top of the degree centrality list were similar to those at the top of the appearance frequency list. It was found that the ranks of the composite neural network and reinforcement learning were changed slightly. The trend of technology development was examined using the appearance frequency of topics and degree centrality. The results showed that machine learning revealed the highest frequency and the highest degree centrality in all years. Moreover, it is noteworthy that, although the deep learning topic showed a low frequency and a low degree centrality between 2009 and 2012, their ranks abruptly increased between 2013 and 2015. It was confirmed that in recent years both technologies had high appearance frequency and degree centrality. TensorFlow first appeared during the phase of 2013-2015, and the appearance frequency and degree centrality of it soared between 2016 and 2018 to be at the top of the lists after deep learning, python. Computer vision and reinforcement learning did not show an abrupt increase or decrease, and they had relatively low appearance frequency and degree centrality compared with the above-mentioned topics. Based on these analysis results, it is possible to identify the fields in which AI technologies are actively developed. The results of this study can be used as a baseline dataset for more empirical analysis on future technology trends that can be converged.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.702-709
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• 2018

A quick-hardened concrete track was developed to improve the aged ballasted track to a concrete track, and applied to earthworks and tunnels of main and urban railways. Rebars for reinforcement are not generally applied to prestressed concrete sleepers. On the other hand, many cracked sleepers have been observed in railroad sites. A wide sleeper, which is one of the main components of quick-hardened concrete track, should be structurally safe and crack-resistant in a ballasted and concrete track to avoid this problem. In particular, a wide sleeper manufactured by a post-tension method must have reinforcing bars applied to the rail-seat section. In this paper, static tests, dynamic tests, and fatigue tests were carried out to compare the flexural strength and crack resistance performance of a wide sleeper with and without reinforcing bars for a quick-hardened concrete track. As a result of the test, if some reinforcing bars are applied appropriately to the rail-seat section of a wide sleeper, it will be possible to prevent the occurrence of cracks, delay the expansion of the crack width, and the flexural fracture.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.2 no.1
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• pp.133-151
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• 2007

In the era of 21st new century. reinforcement of regional competitiveness by establishing innovation system is taking its place of main small and medium sized enterprise policies in major developed countries. The model of regional balanced development for promoting small and medium sized enterprise is a main frame of governmental small and medium sized enterprise policies. which complements national innovation process. And in the level of local area, the model is regional network system, molded in the process of induction, application, modification, proliferation of new technologies and knowledge by local businessman and innovators. This study focused on the strategy development for small and medium sized businesses to increase local competitive power, in terms of regional balanced development. In order to find the real problems and improvement alternatives for local competitive power, this study both reviewed the common strategies and action programs advanced in developed countries for small businesses, and did research on the current economic conditions in local area. Based on the lessons from foreign cases and the analysis of the current situations in small business in local area, the study suggested the model of regional balanced development for promoting small and medium sized enterprise including formation of innovation network system through the invitation of leading firms in the area, industry-university partnerships, and development and attraction for small and medium sized businesses.

• Journal of the Society of Disaster Information
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• v.17 no.4
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• pp.710-721
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• 2021

Purpose: The purpose of this study is to prepare an environment that can provide high-quality 119 rescue services by analyzing the causes of casualties at the water rescue and suggesting improvement plans to prevent them. Method: 5 major cases were analyzed among firefighters' casualty accidents during rescue activities related to the water over the past 10 years for case study. And the causes of the accidents were analyzed in terms of 4 values (Man, Machine, Media, Management) through the 4M analysis technique. Result: ① man: the main causes are lack of awareness of on-site safety, etc ② machine: the problem of the absence of the equipment itself, etc ③ media: the lack of information on the rescue site and the poor rescue environment conditions, ④ management : the main causes were the absence and inadequacy of the response manual for each rescue site, Conclusion: ① man: knowledge of SOP and reinforcement of education and training, etc. ② machine: there are measures such as the introduction of equipment suitable for the changing rescue site, ③media: providing sufficient information about the rescue activity environment and conducting regular road training, ④ management: policy suggestions such as establishment and dissemination of on-site safety management plans and manuals were derived.

• Environmental and Resource Economics Review
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• v.31 no.4
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• pp.777-799
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• 2022

This study examined the latest EU regulatory strengthening trends for refrigerant gases with very large global warming potential (GWP) and derived implications for carbon neutrality. The European Commission recently unveiled an amendment that significantly strengthens the F-gas Regulation. This study presented the meaning of the main contents related to refrigerants in the amendment by comparing them with the current regulations. The main contents of the amendment include drastically reducing the maximum amount of HFCs that can be placed on the market, strengthening regulations related to HFCs allocation, adding products and equipment that use high GWP refrigerants, adding regulated F-gas and updating the GWP of existing gases, and other stricter regulatory designs. This movement of the EU will affect the policy stance of advanced countries such as the United States and Japan, and Korea's policy will also be further strengthened. Therefore, it will be inevitable for related industries to change to next-generation refrigerant gas. Meanwhile, this study also analyzed the latest policy trends related to per- and polyfluoralkyl substances (PFAS) regulation, which were not noted in previsou studies on refrigerants and F-gas. If PFAS's registration of REACH restricted substances, which are being promoted by five European countries, is made, it will have a very big impact on the industry regarding refrigerant gas. In addition, it will be inevitable to thoroughly review each country's greenhouse gas reduction strategies related to F-gas materials, including refrigerants.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.59-78
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• 2024

In tunnel construction, the stability is evaluated by the settlement of adjacent structures and ground, but the shear strain of the ground is the main factor that determines the failure mechanism of the ground due to the tunnel excavation and the change of the operating load, and can be used to review the stability of the tunnel excavation and to calculate the reinforcement area. In this study, a twin tunnel excavation was simulated on a soft ground in an urban area through a laboratory model test to analyze the behavior of the twin tunnel excavation on the adjacent pile grouped foundation and adjacent ground. Both the displacement and the shear strain of ground were obtained using a close-range photogrammetry during laboratory model test. In addition, two-dimensional finite element numerical analysis was performed based on the model test. The results of a back-analysis showed that the maximum shear strain rate tends to decrease as the horizontal distance between the pillars of the twin tunnel and the vertical distance between the toe of the pile group and the crown of the tunnel were decreased. The impact of the second tunnel on the first tunnel and pile group was decreased as the horizontal distance between the pillars of the twin tunnel was increased. In addition, the vertical distance between the toe of the pile group and the crown of the tunnel had a relatively greater impact on the shear strain results than the horizontal distance of the pillars between the twin tunnels. According to the results of the close-range photogrammetry and numerical analysis, the settlement of adjacent pile group and adjacent ground was measured within the design criteria, but the shear strain of the ground was judged to be outside the range of small strain in all cases and required reinforcement.

• Journal of The Korean Association of Information Education
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• v.24 no.2
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• pp.189-199
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• 2020

This study aims to emphasize the necessity of strengthening the information subject through the introduction of a new concept of rights called 'digital environmental rights' and proposes an improvement in the educational composition model of the information culture section in the information subject. Through the introduction of the concept of digital environmental rights, we intend to provide a logical basis for making the information subject a required subject. In addition, we intend to enhance the competencies required for living in a digital environment by improving the structure of the information culture section in the information subject. As a study on this, the logic of the concept of rights required in the digital environment is analyzed and the concept of digital environmental rights applied to it is established. Furthermore, by analyzing relevant curricula in major countries, including the United States, Australia, and Japan, which provide the main basis for digital environmental rights, an improvement plan for the educational composition in the information and culture education sector is formulated. The results of the study are as follows: First, digital environment rights are 'rights to enjoy a pleasant and safe digital environment'. Second, the components of digital environmental rights include rights for the environment (cyberethics), rights of the environment (cybersafety), and rights about the environment (cybersecurity). Third, in the major countries studied various educational structures are being implemented with regard to information-related education contents on the digital citizenship, code ethics, and new technology security.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.92-98
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• 2019

In this study, we developed a repair material incorporating PVA powder resin and nylon fiber into cemented carbide used in the existing field to improve adhesion performance and water tightness with existing concrete. Flexural behavior evaluation was performed. The main experimental variables were PVA powder resin, nylon fiber mixing rate and damage type, and performance tests were conducted to evaluate compressive strength and flexural behavior after repairing materials. It was found that all formulations fully satisfied the required performance of the repair material. The flexural strength test results of the repaired tube specimens showed that the performance of the repaired materials was maximized when the nylon fiber was added and the PVA powder was added in an appropriate amount. The flexural behavior of all the specimens showed the flexural behavior of the structural members with a low rebar ratio, suggesting that the amount of iron wire in the domestic fume pipe was somewhat insufficient. That is, it was confirmed that the amount of reinforcement of the steel wire was somewhat small, so that the concrete was cracked before the behavior of the concrete and the steel wire reached the extreme state, and the concrete was immediately destroyed beyond the tensile strength of the concrete.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.357-366
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• 2010

This paper presents experimental results about shear wall with various lateral reinforcement details in boundary elements. The research objective is to study the structural behavior of shear wall with boundary column confined by rectangular spiral hoops and headed cross ties developed to improve workability in the fabrication of boundary columns. These two details can be fabricated in a factory and put together on-site after being delivered so that the construction work may be reduced. Main parameters in the experimental study were the types of hoop and cross tie: rectangular spiral hoop and headed cross tie vs. standard hoop and cross tie with hook. Four half scaled shear wall specimens with babel shape were made and tested by applying horizontal cyclic load under constant axial force, 10% of nominal compressive strength of concrete. Based on the test result, it was shown that the shear wall with rectangular spiral hoop and headed cross tie in boundary columns has structural capacity compatible with conventional shear wall. The specimen SW-Hh which has bigger hoop bar and higher volumetric ratio of transverse reinforcements than other showed improved energy dissipating characteristic but it presented a rapid reduction of strength after peak point. The results indicates that, it is necessary to consider volumetric ratio of transverse reinforcements as well as hoop space in designing of shear wall with boundary columns for improved strength and ductility.