• Journal of Korea Port Economic Association
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• v.37 no.4
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• pp.127-144
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• 2021

The purpose of this study is to derive service factors based on the "Rail Statistical Yearbook" data of railroad service providers from 1990 to 2019, and to analyze the effect of the service factors on the operating profit ratio(OPR), a representative management performance variable of railroad transport service providers. In particular, it has academic significance in terms of empirical research to evaluate whether the management innovation of the KoRail has changed in line with the purpose of establishing the corporation by dividing the research period into the first period (1990-2003) and the latter (2004-2019). The contents of this study investigated previous studies on the quality of railway passenger transportation service and analyzed the contents of government presentation data related to the management performance evaluation of the KoRail. As an empirical analysis model, a research model was constructed using OPR as a dependent variable and service factor variables of infrastructure, economy, safety, connectivity, and business diversity as explanatory variables based on the operation and management activity information during the analysis period 30 years. On the results of research analysis, OPR is that the infrastructure factor is improved by structural reform or efficiency improvement. And economic factors are the fact that operating profit ratio improves by reducing costs. The safety factor did not reveal the significant explanatory power of the regression coefficient, but the sign of influence was the same as the prediction. Connectivity factor reveals a influence on differences between first period and latter, but OPR impact direction is changed from negative in before to positive in late. This is an evironment in which connectivity is actually realized in later period. On diversity factor, there is no effect of investment share in subsidiaries and government subsidies on OPR.

• Korean Security Journal
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• no.22
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• pp.37-64
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• 2010

Since the September 11, 2001, the motives and objectives of terrorism that have been targeted at hard targets such as key national facilities have now shifted towards soft targets such as subways, department stores, and tourist hotels; the attacks on these soft targets are steadily increasing. Simultaneous, unconventional, and indiscriminate terrorist attacks on civilians has also increased. In November, 2010, nearly forty states of the G20 and B20 (Business 20) will join in international summits to be hosted in Seoul. This coming July, an additional 350 troops will be deployed to Afghanistan for the sustainment of public security. Such events are sensitive topics, and there is the possibility of terrorist movement. Korea has successfully hosted various international events such as the APEC and ASEM Summits, and the 2002 Korea-Japan World Cup. The experiences from these events must be applied to ensure the safety of public facilities against the dangers of terrorism. First, counter-terrorism center must be established for the long-term, above the General Officer level to ensure the safety and efficiency of multilateral, international summits, as well as promoting policies and legislation aimed at preventing terrorism. Second, a terrorist threat management system must be secured and safety measures must be emphasized. Third, a fundamental structure must be established for the prevention of terrorism on public facilities, as well as legal and government action against the new threat of IED. Fourth, the police and fire fighting networks' must have a firm rapid response posture on the scene of an attack. Fifth, the state of mentality on the recognition of terrorist threats must be changed and restructured by promoting to and educating the population. Sixth, prevention measures must be established via research and academia. Seventh, for the guarantee of security in public facilities, safety management should employ cutting edge technology such as the 3D SICS and further develop and apply such technology. All methods and resources must be fully utilized for the establishment and strengthening terrorism prevention measures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.765-778
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• 2008

Performance Profiles are essential to predict the performance variation over time for the bridge management system (BMS) based on risk management. In general, condition profiles based on experts opinion and/or visual inspection records have been used widely because obtaining profiles based on real performance is not easy. However, those condition profiles usually don't give a good consistency to the safety of bridges, causing practical problems for the effective bridge management. The accuracy of performance evaluation is directly related to the accuracy of BMS. The reliability of the evaluation is important to produce the optimal solution for distributing maintenance budget reasonably. However, conventional methods of bridge assessment are not suitable for a more sophisticated decision making procedure. In this study, a method to compute quantitative performance profiles has been proposed to overcome the limitations of those conventional models. In Bridge Management Systems, the main role of performance profiles is to compute and predict the performance of bridges subject to lifetime activities with uncertainty. Therefore, the computation time for obtaining an optimal maintenance scenario is closely related to the efficiency of the performance profile. In this study, the Response Surface Method (RSM) based on independent and important design variables is developed for the rapid computation. Steel box bridges have been investigated because the number of independent design variables can be reduced significantly due to the high dependency between design variables.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.722-729
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• 2010

Over the last decades, much consideration has been given to microbiological and chemical risks, especially when wastewater was reclaimed as water resources for urban water, irrigation water and recreational water etc. We investigated the performance of UV-based processes such as UV and UV/$H_2O_2$ for both the removal of pharmaceuticals and personal care products (PPCPs) as an emerging chemical and the inactivation of pathogen with bench-scale experimental study. 38 kinds of PPCPs including antibiotics and analgesics were detected from secondary effluent used as tested water. Bench-scale experimental study showed that UV process would require considerable UV dose for the effective PPCPs removal. Contrarily, PPCPs removal efficiency significantly improved by the combination of $H_2O_2$ with UV even at a lower UV dose and, moreover, their removal efficiency increased with the increased initial $H_2O_2$ concentration. Besides naproxen (>89%), concentrations of all the investigated PPCPs decreased by more than 90% of their initial concentrations under $923\;mJ/cm^3$ of UV dose and 6.2 mg/L of $H_2O_2$. Previous studies showed that this operational condition could get 4~5 log inactivation for Total coliform, indicating that UV/$H_2O_2$ process will be appropriate to comply with the criteria of California Title 22 for Total coliform.

• Korean Journal of Construction Engineering and Management
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• v.8 no.5
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• pp.142-151
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• 2007

The rock excavation work on the sea is planned as underwater process if the elevation of the rock is lower than the M.S.L.(Mean Sea Level). However, in case of West and South sea which are largely different between the rise and fall of the tide, the earth work can be performed on the ground while the work surface is exposed above the sea according to the tide cycle. Thus, it may a good substitute to make up for shortcomings of underwater construction works such as safety problems of workers, loss of efficiency and increasement of construction costs. But the difference between the height of the rock excavation surface and the water surface changed by the tide makes the exposure time of work surface, that is the possible working hours be changed. Also, it may cause the changes of construction cost. Thus, this study analyzes the economical efficiency of the construction method using the difference between the rise and fall of the tide in comparison with the construction method which is performed under the sea, and it also suggests the way to analyze the economical working hours by estimating the possible working hours on the ground. We also try to find out the application possibility of the way like the rock excavation work on the sea using the difference between rise and fall of the tide.

• Journal of Convergence for Information Technology
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• v.10 no.11
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• pp.55-63
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• 2020

The IoT technology is a field that applies and converges the technologies in the existing industrial environment, instead of new technologies. The IoT technology is releasing various application services converged with other industries such as smart home, healthcare, construction, and automobile, and it is also possible to secure the work efficiency and convenience of users of IoT-based technologies. However, the security threats occurring in the IoT-based technology environment are succeeding to the vulnerability of the existing wireless network environment. And the occurrence of new and variant attacks in the combination with the ICT convergence environment, is causing damages. Thus, in the IoT technology-based environment, it would be necessary to have researches on the safe transmission of messages in the communication environment between user and device, and device and device. This thesis aims to design a safe communication protocol in the IoT-based technology environment. Regarding the suggested communication protocol, this thesis performed the safety analysis on the attack techniques occurring in the IoT technology-based environment. And through the performance evaluation of the existing PKI-based certificate issuance system and the suggested communication protocol, this thesis verified the high efficiency(about 23%) of communication procedure. Also, this thesis verified the reduced figure(about 65%) of the issued quantity of certificate compared to the existing issuance system and the certificate management technique.

• Journal of Industrial Convergence
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• v.22 no.4
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• pp.1-9
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• 2024

Smart factories represent production facilities where cutting-edge information and communication technologies are fused with manufacturing processes, reflecting rapid advancements and changes in the global manufacturing sector. They capitalize on the integration of robotics and automation, the Internet of Things (IoT), and the convergence of artificial intelligence technologies to maximize production efficiency in various manufacturing environments. However, the smart factory environment is prone to security threats and vulnerabilities due to various attack techniques. When security threats occur in smart factories, they can lead to financial losses, damage to corporate reputation, and even human casualties, necessitating an appropriate security response. Therefore, this paper proposes a security authentication mechanism for safe communication in the smart factory environment. The components of the proposed authentication mechanism include smart devices, an internal operation management system, an authentication system, and a cloud storage server. The smart device registration process, authentication procedure, and the detailed design of anomaly detection and update procedures were meticulously developed. And the safety of the proposed authentication mechanism was analyzed, and through performance analysis with existing authentication mechanisms, we confirmed an efficiency improvement of approximately 8%. Additionally, this paper presents directions for future research on lightweight protocols and security strategies for the application of the proposed technology, aiming to enhance security.

• Journal of the Korean GEO-environmental Society
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• v.13 no.7
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• pp.5-12
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• 2012

Recently the installation of reinforced earth retaining walls in the domestic construction site has increased, surpassing conventional RC walls. These reinforced walls have various types depending on the reinforcing material, installation method and the form of face panel. However, there are difficulties in design and construction management due to the unproved safety of construction method. In case of reinforcing materials, despite the fact that they come in all different sizes and types produced by small businesses or partially imported with cheap price and low quality, no proper standards for designing the walls have been suggested. In order to apply reinforced retaining wall system to broad cases and design the walls effectively considering site conditions, specific design and construction guidelines for efficient construction management are needed. In conclusion, this study verified that reduction factors can be greatly affected by grain sizes and stiffness of backfill materials and granularity range, therefore in case of relatively large construction site, it is required to redesign the reinforced retaining wall by evaluating site installation resistance test, applying respective reduction factors to each backfill material and select the right geogrid depending on the usage of retaining wall so as to enhance the safety of reinforced earth retaining walls with efficiency.

• Korean Journal of Construction Engineering and Management
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• v.16 no.4
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• pp.98-106
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• 2015

VE aims at reduction in a budget, improvement of function, structural safety and quality security for public construction projects. However, there is possibility for the structural safety and quality security review to be insufficient because related regulations are mostly composed of analysis on economic efficiency of design. In addition, due to the misconception about VE as a cost saving methodology, an alternative is being presented which still focuses mainly on cost saving, but with no objective evaluation of function related to cost. In order to improve this, the government adopted the reduction of life cycle cost and proposal of value improvement, and let people specify the cost and function of the original plan versus the alternative plan, and the value changes between them. However, it is written mainly into practical convenience rather than theoretical basis since a specific way is not suggested. The current method sets a different starting point by applying the attributional difference of function and cost. Furthermore, an evaluation standard for correlating is an important element in rational decision making for assessing and choosing an alternative. This paper analyzes the process and method of function & cost scoring when performing VE and suggests a mathematical normalization model in order to support rational decision making when selecting an optimum plan.

• Korean Journal of Construction Engineering and Management
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• v.17 no.3
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• pp.143-155
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• 2016

Recently, the interest on applying AVM(Around View Monitoring) systems in construction equipments have been increasing due to the demand for better control, work efficiency and safety. Most of the existing AVM systems have been developed focusing on the application in automobiles and only several AVM systems have been developed for construction equipments. However, the original technology of AVM remained the same as in the automobiles that failed to consider the main properties of construction equipments and suggest appropriate range of AVM display (Top-view). Therefore, the purpose of this study is to suggest a pilot type of AVM system for construction equipment. Accordingly, literature review, deduction of main consideration factors, selection of sensors, system design, algorithm development of a pilot type of AVM system for construction equipment have been conducted. A laboratory experiment has also been conducted for the deduction of further improvements. As a result, a minimum image refresh rate of 20 fps has been achieved that clearly reflects the actual situation of the equipment and also, the actual motions of Boom, Arm, Bucket have been displayed appropriately on the AVM system based on the angle data collected by sensors. However, the experiment results have also shown that the following tasks still remain for future work: 1)Improvement of AVM image interpolation, 2)Development of calibration module for variety construction equipment.