• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.26-35
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• 2007

The vehicle of urban transit is a complex system that consists of various electric, electronic, and mechanical equipments, and the maintenance cost of this complex and large-scale system generally occupies sixty percent of the LCC (Life Cycle Cost). For reasonable establishing of maintenance strategies, safety security and cost limitation must be considered at the same time. The concept of system reliability has been introduced and optimized as the key of reasonable maintenance strategies. For optimization, three preceding studies were accomplished; standardizing a maintenance classification, constructing RBD (Reliability Block Diagram) of VVVF (Variable Voltage Variable Frequency) urban transit, and developing a web based reliability evaluation system. Historical maintenance data in terms of reliability index can be derived from the web based reliability evaluation system. In this paper, we propose applying inverse problem analysis method and hybrid neuro-genetic algorithm to system reliability optimization for using historical maintenance data in database of web based system. Feed-forward multi-layer neural networks trained by back propagation are used to find out the relationship between several component reliability (input) and system reliability (output) of structural system. The inverse problem can be formulated by using neural network. One of the neural network training algorithms, the back propagation algorithm, can attain stable and quick convergence during training process. Genetic algorithm is used to find the minimum square error.

• Journal of Korean Society of Archives and Records Management
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• v.3 no.1
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• pp.111-127
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• 2003

Web-based information resources should be managed and used methodically in the same manner as the paper-based resources are managed and used. It is necessitated by the prevalence of web-based delivery of a variety of information. To develop a web-based digital collection, it is critical to establish a set of standardized evaluation criteria for web-resources. The evaluation criteria needs to include authority, trustworthy, reliability, functionality, relatedness, accessibility, structure, design, user support, and security related matters. However, it is also necessary to have certain flexibility to either emphasize or include particular evaluation criteria to reflect varying characteristics of the web resources especially for the purpose of developing an effective digital collection. In addition, it is essential to review the evaluation criteria with respect to value, demand, duplication prevention, and intellectual property, which are relevant to the web-based digital collection development. Finally, various strategies were suggested as means to develop more effective web-based digital resource collection. These strategies include organizing a selection committee to ensure the objectivity and consistency in web-resource evaluation; developing a model for web-based digital resource collection; sharing new standards, protocols, markups, and metadata with other digital libraries; and developing user-centered digital resource collection.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.80-87
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• 2015

The proliferation of the Internet and communication technologies and applications, besides the conventional retailers, has led to a new form of distribution channel, namely home sopping through the telephone, TV, catalog or the Internet. The conventional and new distribution channels have different transaction costs perceived by the consumers in the following perspectives: the accessibility to the product information, the traffic cost and the opportunity cost for the time to visit the store, the possibility of 'touch and feel' to test the quality of the product, the delivery time and the concern for the security for the personal information. Difference in the transaction costs between the distribution channels results in the different selling prices even for the same product. Moreover, distribution channels with different selling prices necessarily result in different business surpluses. In this paper, we study the multilateral bargaining strategy of a manufacturer who sells a product through multiple distribution channels with different transaction costs. We first derive the Nash equilibrium solutions for both simultaneous and sequential bargaining games. The numerical analyses for the Nash equilibrium solutions show that the optimal bargaining strategy of the manufacturer heavily depends not only on the degree of competition between the distribution channels but on the difference of the business surpluses of the distribution channels. First, it is shown that there can be four types of locally optimal bargaining strategies if we assume the market powers of the manufacturer over the distribution channels can be different. It is also shown that, among the four local optimal bargaining strategies, simultaneous bargaining with the distribution channels is the most preferred bargaining strategy for the manufacturer.

• Safety and Health at Work
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• v.12 no.3
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• pp.304-310
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• 2021

Background: Healthcare settings have been recognized among the most hazardous places to work. Based on the five categories of occupational hazards that were identified by the ILO and WHO, this study aimed to analyze policy framework relevant to occupational health protection of health workers (HWs) in public health service in China, then discussed how to share the experience of the National Health Service (NHS) England for improvement. Methods: Based on policy learning theories, policy analysis and qualitative interview were used in this study. Results: In the Chinese public health service, at least five laws related to the regulation of occupational health protection for HWs; however, enforcement of relevant laws was separated and multi-centered; the national monitoring system, which targeted to occupational hazards and health outcome for HWs in China, had yet to be developed; the top three priorities were workplace violence, bloodborne pathogens, and musculoskeletal disorders; national strategies included Security Hospital, and Healthy China 2030. In NHS England, three laws were fundamental; several monitoring systems had been set up, including NHS Staff Survey, Commissioning for Quality and Innovation incentive scheme; mental health, musculoskeletal problem, and nutrition disorder and overweight were raised great concern; Health and Safety, and NHS Healthy Workforce Program were critical nationwide strategies. Conclusion: There were several similarities as well as differences between the Chinese public health system and NHS England, which laid foundation of learning by China. Recommendations of improving occupational health policies in China were provided, based on the lessons learned from the NHS England.

• Journal of Practical Engineering Education
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• v.11 no.1
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• pp.25-31
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• 2019

The purpose of this study is to investigate the difference between motivation and learning strategies of students who have received academic probation and who have not while attending engineering college. The subjects of this study were engineering college students in Seoul and they participated in the learning strategy test at the teaching and learning center. The subjects of this study were 553 students, 22 of whom received academic probation and 531 didn't. In order to achieve the purpose of this study, we used MLST (Multi-dimensional Learning Strategy test) learning strategy checklists of Korea Guidance, which is a standardized test. A t-test was conducted to compare motivational and learning strategies between students with and without academic probation. As a result, the motivation score of the students with the academic probation was lower than that of those without the academic probation, and the score of the time management and note taking factors of the students with the academic probation were lower than those of the students without the academic probation.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.49-55
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• 2021

Recently, with the development of database, it is possible to store a lot of data generated in finance, security, and networks. These data are being analyzed through classifiers based on machine learning. The main problem at this time is data imbalance. When we train imbalanced data, it may happen that classification accuracy is degraded due to over-fitting with majority class data. To overcome the problem of data imbalance, oversampling strategy that increases the quantity of data of minority class data is widely used. It requires to tuning process about suitable method and parameters for data distribution. To improve the process, In this study, we propose a strategy to explore and optimize oversampling combinations and ratio based on various methods such as synthetic minority oversampling technique and generative adversarial networks through genetic algorithms. After sampling credit card fraud detection which is a representative case of data imbalance, with the proposed strategy and single oversampling strategies, we compare the performance of trained classifiers with each data. As a result, a strategy that is optimized by exploring for ratio of each method with genetic algorithms was superior to previous strategies.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.201-208
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• 2024

This study aims to analyze the causes and characteristics of conflicts arising from the relocation of national defense facilities, focusing on the Jeonju Aviation School relocation project, and to explore effective conflict management strategies. As urbanization progresses, military facilities initially located on the outskirts of cities have been integrated into urban areas, increasing the need for relocation. This process frequently results in conflicts among the government, the military, and local residents due to differing interests. This study employs a combination of literature review and surveys to examine perceptions of conflict causes and resolution strategies. The findings reveal that the primary conflict factors include inadequate information provision and consultation, noise and property value decline, and unilateral decision-making processes. Participatory decision-making was found to be effective in resolving conflicts. Based on these findings, the study proposes policy recommendations such as institutional improvements, enhanced information disclosure and communication, comprehensive compensation systems, and strengthened expertise in conflict management. This research is significant in empirically confirming the importance of participatory decision-making in national defense facility relocation projects and providing specific policy suggestions for conflict management.

• Convergence Security Journal
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• v.12 no.1
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• pp.35-42
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• 2012

Increase of data traffic and the advent of new real-time services require to change from the traditional TDM-based (Time Division Multiplexing) networks to the optical networks that soft and dynamic configuration. Voice and lease line services are main service area of the traditional TDM-based networks. This optical network became main infrastructure that offer many channel that can convey data, video, and voice. To provide high resilience against failures, Packet-optical networks must have an ability to maintain an acceptable level of service during network failures. Fast and resource optimized lightpath restoration strategies are urgent requirements for the near future Packet-optical networks with a Generalized Multi-Protocol Label Switching(GMPLS) control plane. The goal of this paper is to provide packet-optical network with a hierarchical multi-layer recovery in order to fast and coordinated restoration in packet-optical network/GMPLS, focusing on new implementation information. The proposed schemes do not need an extension of optical network signaling (routing) protocols for support.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.961-972
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• 2016

For securing password-based authentication, a user must select and manage a strong password that has sufficient length and randomness. Unfortunately, however, it is known that many users are likely to choose easy-to-remember weak passwords and very poorly manage them. In this paper, we study a domestic user case of password selection and management. We conducted a survey on 327 domestic users and analyzed their tendency on password creation and update strategies, and also on the password structure and account management. We then analyzed an effect of a server's password creation rule on a structure of a user-chosen password. Our findings include that there are password structures and special characters that users significantly prefer while the effect of server's password creation rule is insignificant.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.19-28
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• 2017

False data injection attacks have recently been introduced as one of important issues related to cyber-attacks on electric power grids. These attacks aim to compromise the readings of multiple power meters in order to mislead the operation and control centers. Recent studies have shown that if a malicious attacker has complete knowledge of the power grid topology and branch admittances, s/he can adjust the false data injection attack such that the attack remains undetected and successfully passes the bad data detection tests that are used in power system state estimation. In this paper, we investigate that a practical false data injection attack is essentially a cyber-attack with uncertain information due to the attackers lack of knowledge with respect to the power grid parameters because the attacker has limited physical access to electric facilities and limited resources to compromise meters. We mathematically formulated a method of identifying the most vulnerable locations to false data injection attack. Furthermore, we suggest minimum topology changes or phasor measurement units (PMUs) installation in the given power grids for mitigating such attacks and indicate a new security metrics that can compare different power grid topologies. The proposed metrics for performance is verified in standard IEEE 30-bus system. We show that the robustness of grids can be improved dramatically with minimum topology changes and low cost.