• KIPS Transactions on Software and Data Engineering
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• v.3 no.2
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• pp.65-72
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• 2014

Change coupling is a measure to show how strongly change-related two entities are. When two source files have been frequently changed together, they are regarded as change-coupled files and they will probably be changed together in the near future. In the previous studies, the change coupling between two files is defined with the number of common changed time, that is, common commit time of the files. However, the frequency-based technique has limitations because of 'tangled changes', which frequently happens in the development environments with version control systems. The tangled change means that several code hunks have been changed at the same time, though they have no relation with each other. In this paper, the change types of the code hunks are also used to define change coupling, in addition to the common commit time of target files. First, the frequency vector based on change types are defined with the extracted change types, and then, the similarity of change patterns are calculated using the cosine similarity measure. We conducted experiments on open source project Eclipse JDT and CDT for case studies. The result shows that the applicability of the proposed method, compared to the previous studies.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.219-237
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• 2020

Rapid economic development and urban population growth have been increasing the necessity for underground space exploration and utilization due to the need of upgrading and expanding the existing infrastructures. TBM has been widely used to construct underground structures with high advance rate and minimal ground disturbance. Two important design parameters, which are available thrust capacity and cutterhead torque, should be estimated for any project in addition to proper selection of TBM type. However, the conventional thrust force and torque estimation model only depends on the empirical equation, which hinders the design process of the optimal thrust hydraulic system and the appropriate hydraulic components. In this study, four thrust and torque calculation models are derived and explained. For TBM design practice, the four estimation models are compared and discussed.

• Journal of Soil and Groundwater Environment
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• v.23 no.2
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• pp.1-14
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• 2018

The recent increase in demand for lithium has led to the development of new brine prospects, The brines are hosted in closed salar basin aquifers of two types that are mature halite salars and immature clastic salars. Salar brines also contain other elements of commercial interest, most notably potassium and boron. As a result, there has been a plethora of new exploration projects focused on the brines hosted in the aquifers of the intermontane-closed basins. The estimate of lithium resources and reserves in these salars depends on a detailed knowledge of aquifer geometry, porosity, and brine grade. Because the resource is in a fluid state, it has the propensity to move, mix, rearrange itself relatively rapidly during the course of a project lifetime, and lower recovery factors compared with most metalliferous and industrial mineral deposits due to reliance on pumping of the brine from wells for extraction. This is unlike any other type of metallic mineral resource and hence a different approach specially focusing on hydrogeology and brine hydrology is required for these prospects.

• Journal of the Korean Society for Library and Information Science
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• v.53 no.4
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• pp.373-397
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• 2019

Recent disasters are a complex and growing trend. In order to effectively prepare for and respond to disasters that occur without notice, it is very important to use scientific information related to disaster and safety in addition to the standardized disaster safety information that is used. In this paper, we searched and selected major journals in the field of disaster & safety and conducted various network analysis studies using the classification scheme for development of integrated metadata for disaster & safety information developed through Disaster & Safety Information Sharing Platform R&D project as well as KSCD. Also, we have constructed and analyzed citation network, co-authorship network and keyword network through data identification and preprocessing of research paper contents. As a result of this study, based on the network constructed by information analysis unit, the network structure between core domestic and foreign journals, major research institutes, core keywords and individual information by disaster & safety type was identified in detail, and the analysis results were presented on a case-by-case basis.

• Journal of Digital Convergence
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• v.16 no.11
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• pp.137-147
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• 2018

To prepare for and implement policies for the Fourth Industrial Revolution, which is characterized by convergence, super-connectivity, and AI, this study summarized the effects and characteristics of individual technologies on our society and discussed the issues with humanity and social science perspectives. As a result, in terms of AI technology, the issues of job losses, project-type works, basic income and robot taxes, accountability of AI, and algorithm inequality were dealt with. Security, cyber hacking and privacy infringement issues were highlighted in big-data technology. In the part of block-chain and bioengineering, the society of decentralization, the concentration, digital divide, and ethical issues were discussed. On-demand economic aspects highlighted the problems of civil ethics and human commercialization. Lastly, the development of VR is discussed including side effects such as cyber-syndrom, avoidance of reality, and so on.

• Journal of Internet of Things and Convergence
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• v.7 no.2
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• pp.1-6
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• 2021

In recent years, many people are living in a space limited by rapid global industrial development and economic growth, and rapid urbanization is underway, with the global urban population estimated to be more than 70 percent in 2050. Due to rapid urbanization, government-led smart city models are being developed and introduced to solve various urban problems such as disaster safety, air pollution, water pollution, energy shortage, disease, crime and transportation. However, since ICT technology of public housing is being developed as a type of social overhead capital project, it is necessary to develop micro-smart city projects that residents can feel by developing services such as public safety, living environment, living welfare, and energy management for public housing residents. Therefore, in this paper, the smart platform model of public housing for smart city in the era of the Fourth Industrial Revolution is planned and presented.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.476-487
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• 2022

International research cooperation is emerging as one of the strategies for improving research performance. Therefore, in this study, through the analysis of research reports on the theme of international research cooperation, the subject and issues of international research cooperation were identified and the characteristics of these studies were confirmed. To this end, related report data were constructed, statistical data analysis and big data analysis of the data were performed. Considering the current international research cooperation network, it is necessary to conduct international research cooperation centered on developing countries while paying attention to the increase in China's proportion of international research cooperation. Second, it is necessary to emphasize the importance of international research cooperation in various countries, including developing countries, in that the interdependence of research between countries increases and the citation index of actual joint research is higher. Third, it can be seen that the subject field in which international research cooperation can be activated may vary depending on the type of support project. Therefore, it suggests that in order for international research cooperation on more diverse topics to be carried out, projects supporting them must also be diversified.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.345-352
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• 2022

The existing NATM (New Austrian Tunneling Method) has induced civil compliants due to blasting vibration and noise. Machanized excavation methods such as TBM (Tunnel Boring Machine) are being adopted in the planning and construction of tunneling projects. Shield TBM method is composed of repetition processes of TBM excavation and segment installation, the machine has to be stopped during the later process. Consecutive excavation technology using helical segment is under developing to minimize the stoppage time. The modification of thrust jacks and module are planned to ensure the advance force acting on the inclined surface of helical segment. Also, the integrated system design of hydraulic circuit will be remodeled. This means that the system deactivate the jacks on the installing segment while the others automatically act the thrusting forces on the existing segments. This report briefly introduces the mechanical research part of the current consecutive excavation technological development project of TBM.

• Korean Journal of Community Nutrition
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• v.28 no.2
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• pp.95-103
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• 2023

Objectives: The budget gap in the health sector of local governments affects the supply of health services, which can cause the health gap. This study classified local governments according to their financial characteristics, such as local financial independence and health budget level. It analyzed the health behaviors and disease prevalence of local residents to examine the effect of local government financial investment on the health of local residents. Methods: To classify types according to the financial characteristics of local governments, financial independence and the health budget data for 17 local governments were collected from the local fiscal yearbook of the Ministry of Public Administration and Security. The prevalence of chronic diseases and healthy behavior was compared using the 16,333 data of adults between the ages of 30 and 65 years among the original data of the National Health and Nutrition Examination Survey (2016-2020). Results: Cluster analysis was used to classify local governments into five clusters according to the health financial capacity type. A comparison of the prevalence of local residents by cluster revealed a similar prevalence of hypertension, diabetes, and hypercholesterolemia. On the other hand, the obesity rate (P < 0.01), high-risk drinking rate (P < 0.01), aerobic physical activity rate (P < 0.001), and healthy eating practice rate (P < 0.001) were significantly different. In addition, an analysis of the odds ratio based on the Seoul area revealed a higher risk of health behavior of non-Seoul residents. Conclusions: It is necessary to review the universal health promotion project budget considering the degree of regional financial vulnerability from the viewpoint of health equity to narrow the health gap among regions.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.119-127
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• 2022

Most of the construction works are conducted outdoors, so the construction workers are affected by weather conditions such as temperature, humidity, and wind velocity which can be evaluated the thermal comfort as environmental factors. In our previous researches, it was found that construction accidents are usually occurred in the discomfort ranges. The safety management, therefore, should be planned in consideration of the thermal comfort and measured by a specialized simulation tool. However, it is very complex, time-consuming, and difficult to model. To address this issue, this study is aimed to develop a framework of a prediction model for improving the prediction accuracy about outdoor thermal comfort considering environmental factors using machine learning algorithms with hyperparameter tuning. This study is done in four steps: i) Establishment of database, ii) Selection of variables to develop prediction model, iii) Development of prediction model; iv) Conducting of hyperparameter tuning. The tree type algorithm is used to develop the prediction model. The results of this study are as follows. First, considering three variables related to environmental factor, the prediction accuracy was 85.74%. Second, the prediction accuracy was 86.55% when considering four environmental factors. Third, after conducting hyperparameter tuning, the prediction accuracy was increased up to 87.28%. This study has several contributions. First, using this prediction model, the thermal comfort can be calculated easily and quickly. Second, using this prediction model, the safety management can be utilized to manage the construction accident considering weather conditions.