• Journal of applied mathematics & informatics
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• v.41 no.6
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• pp.1257-1274
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• 2023

Rotating machines heavily rely on an intricate network of interconnected sub-components, with bearing failures accounting for a substantial proportion (40% to 90%) of all such failures. To address this issue, intelligent algorithms have been developed to evaluate vibrational signals and accurately detect faults, thereby reducing the reliance on expert knowledge and lowering maintenance costs. Within the field of machine learning, Artificial Immune Systems (AIS) have exhibited notable potential, with applications ranging from malware detection in computer systems to fault detection in bearings, which is the primary focus of this study. In pursuit of this objective, we propose a novel procedure for detecting novel instances of anomalies in varying operating conditions, utilizing only the signals derived from the healthy state of the analyzed machine. Our approach incorporates AIS augmented by Dynamic Time Warping (DTW). The experimental outcomes demonstrate that the AIS-DTW method yields a considerable improvement in anomaly detection rates (up to 53.83%) compared to the conventional AIS. In summary, our findings indicate that our method represents a significant advancement in enhancing the resilience of AIS-based novelty detection, thereby bolstering the reliability of rotating machines and reducing the need for expertise in bearing fault detection.

• International journal of advanced smart convergence
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• v.12 no.4
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• pp.8-19
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• 2023

This paper presents advancement in multi- unmanned aerial vehicle (UAV) cooperative area surveillance, focusing on optimizing UAV route planning through the application of genetic algorithms. Addressing the complexities of comprehensive coverage, two real-time dynamic path planning methods are introduced, leveraging genetic algorithms to enhance surveillance efficiency while accounting for flight constraints. These methodologies adapt multi-UAV routes by encoding turning angles and employing coverage-driven fitness functions, facilitating real-time monitoring optimization. The paper introduces a novel path planning model for scenarios where UAVs navigate collaboratively without predetermined destinations during regional surveillance. Empirical evaluations confirm the effectiveness of the proposed methods, showcasing improved coverage and heightened efficiency in multi-UAV path planning. Furthermore, we introduce innovative optimization strategies, (Foresightedness and Multi-step) offering distinct trade-offs between solution quality and computational time. This research contributes innovative solutions to the intricate challenges of cooperative area surveillance, showcasing the transformative potential of genetic algorithms in multi-UAV technology. By enabling smarter route planning, these methods underscore the feasibility of more efficient, adaptable, and intelligent cooperative surveillance missions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.11
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• pp.2987-3002
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• 2023

In 2015, the number of senior citizens aged 65 and over in Korea was 6,662,400, accounting for 13.1% of the total population. Along with these social phenomena, risk information related to the elderly is increasing every year. In particular, a fall accident caused by a fall can cause serious injury to an elderly person, so special attention is required. Therefore, in this paper, we implemented a system that monitors fall accidents and informs them in real time to minimize damage caused by falls. To this end, beacon-based indoor location positioning was performed and biometric information based on an integrated module was collected using various sensors. In other words, a multi-functional sensor integration module was designed based on Arduino to collect and monitor user's temperature, heart rate, and motion data in real time. Finally, through the analysis and prediction of measurement signals from the integrated module, damage from fall accidents can be reduced and rapid emergency treatment is possible. Through this, it is possible to reduce the damage caused by a fall accident, and rapid emergency treatment will be possible. In addition, it is expected to lead a new paradigm of safety systems through expansion and application to socially vulnerable groups.

• Asia pacific journal of information systems
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• v.32 no.4
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• pp.707-727
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• 2022

Industrial revolution 4.0 makes business competition more challenging and will impact the instability of the company's financial performance. Dynamic environmental conditions make it difficult for companies to make predictions in making decisions. Investing in information technology (IT) is one way for companies to maintain financial stability and competitive advantage in dynamic competition. Resource-Based Theory (RBT) explains that information technology (IT) is a resource that can create a competitive advantage for the company. This study aims to examine the moderating role of dynamic industrial environments and IT strategic emphasis on the relationship between a lag effect of IT investment and firm's financial performance volatility. Using the data of companies listed on the Indonesia Stock Exchange (IDX) for five years starting from 2013-2017, the method used to estimate the research model's parameters is the generalized method of moments (GMM) approach. The results show that the industrial environment and the emphasis on IT strategy have a role in moderating and strengthening the relationship between the time lag in IT investment in reducing the firm's financial performance volatility.

• Nuclear Engineering and Technology
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• v.24 no.1
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• pp.14-29
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• 1992

COMCAF, a computer code for the common-cause failure analysis, is developed to treat the common-cause failures in nuclear power plants. In the treatment of common-cause failures, the minimal cut sets of the system are obtained first without changing the fault-tree structure. The occurrence probabilities of the minimal cut sets are then calculated accounting for the common-cause failures among components in the same minimal cut set or in different minimal cut sets. The basic parameter model is used to model the common-cause failures between similar or identical components. For dissimilar components, the assumption of symmetry used in the basic parameter model is applied to the basic events affecting two or more components. The top event probability is evaluated using the inclusion-exclusion method. In addition to the common-cause failures of components in the same minimal cut sets, failures of components in the different minimal cut sets are also easily accounted for by this method. This study applied this common-cause failure analysis to the PWR auxiliary feedwater system. The results in the top event probability for the system are compared with those of no common-cause failures.

• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.249-260
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• 2006

This study is to investigate how mobile internet service users recognize that Wibro service providers should be equipped with what type of organizational capabilities. Especially. this stud y, in exploratory point of view, examines the recognition is differed by characteristics of Wibro service users. This study also is to suggest a few of research propositions regarding the relations hips between organizational capabilities and characteristics of Wibro service users from various statistical analyses. To accomplish these research purposes, this study defined characteristics of Wibro service users (sender, age, job) and organizational capabilities of Wibro service provide rs ( accounting/finance capabilities, production/service capabilities, marketing/sales capabilities. research and development/technology capabilities) based on the review of past mobile interne t service related studies. And then, this study performed not only questionnaire survey on latent Wibro service users but also various statistical analyses.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.339-348
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• 2014

This study searches an improvement scheme of auditing on international financial environment since enforcing IFRS in order to secure transparency and reliability in corporate accounting and credibility in external audit from 2011 K-IFRS. As improvement schemes for the issue of the audit on K-GAAP are: First, the guarantee of the auditor's qualities of duties and talents about the lack of accountability and awareness and independence of auditor are needed. Secondly, the free acceptance or certified public accountant is adopted. Third, the non-Executive Director shall be granted. Fourth, the external auditor CPA and Auditor's remuneration should be increased. Fifth, the auditor's shares shall be limited. Sixth, the external audit to supervise and the ratio of supervision should increase. Finally, the foreign corporation for the time being limited to increase our competitiveness.

• Journal of Communications and Networks
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• v.4 no.4
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• pp.351-362
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• 2002

In this paper, we introduce a new approach to the minimum energy routing (MER) for next generation (NG) multihop wireless networks. We remove the widely used assumption of deterministic, distance-based channel model is removed, and analyze the potentials of MER within the context of the realistic channel model, accounting for shadowing and fading. Rather than adopting the conventional unrealistic assumption of perfect power control in a distributed multihop environment, we propose to exploit inherent spatial diversity of mobile terminals (MT) in NG multihop networks and to combat fading using transmit diversity. We propose the cooperation among MTs, whereby couples of MTs cooperate with each other in order to transmit the signal using two MTs as two transmit antennas. We provide the analytical framework for the performance analysis of this scheme in terms of the feasibility and achievable transmit power reduction. Our simulation result indicate that significant gains can be achieved in terms of the reduction of total transmit power and extension of network lifetime. These gains are in the range of 20-100% for the total transmit power, and 25-90% for the network lifetime, depending on the desired error probability. We show that our analytical results provide excellent match with our simulation results. The messaging load generated by our scheme is moderate, and can be further optimized. Our approach opens the way to a new family of channel-aware routing schemes for multihopNG wireless networks in fading channels. It is particularly suitable for delivering multicast/ geocast services in these networks.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.147-153
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• 2012

This paper has investigated the impact of corporate donation expenditure which has recently drawn great attention in Korean society on businessl performance and conducted an empirical analysis on the causal relations. In addition, concurrent effect has been analyzed using cross-sectional data between two variables (corporate donation expenditure and business performance) while sequential effect has been examined using panel data. The result of this study can be summarized as follows: First, corporate donation expenditure had a positive impact on ROA and ROS. However, PER and ROE had no impact on corporate donation expenditure Second, cumulative effcet of corporate cash donation would have a bigger impact on short-term business performance than long-term performance. In the future, The results of this study is expect through cash donations in the social contribution to be more aggressive in carrying out social responsibilities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.569-574
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• 2018

This paper proposes and implements a LoRa-based emergency exit guide system which can direct the optimal refuge path accounting for the real state of the fires. Each 4-way emergency exit guide sign presents a right direction through one of four LED signs toward the possible exit dynamically calculated by the shortest path algorithm. We constructed a simulation environment with 8 spots of the emergency exit guide signs and 2 exits, which can simulate variant cases of fire accidents, and showed that the proposed algorithm can presents the right guidance for each emergency exit guide sign. We also evaluated the performances of LoRa-based wireless communications using a self developed communication module in the various indoor and outdoor environments. The proposed system can be applied to small and medium sized buildings as well as larger ones in terms of cost efficiency, in which there's no needs to invest for the complex equipments except only sensors and emergency exit guide signs.