• Convergence Security Journal
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• v.20 no.5
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• pp.11-17
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• 2020

With the increase in cases of using Bluetooth devices used in the electric vehicle charging systems, security issues are also raised. Although various technical efforts have beed made to enhance security of bluetooth technology, various attack methods exist. In this paper, we propose an intelligent Bluetooth intrusion detection system based on a well-known machine learning method, Hidden Markov Model, for the purpose of detecting intelligently representative Bluetooth attack methods. The proposed approach combines packet types of H4, which is bluetooth transport layer protocol, and the transport directions of the packet firstly to represent the behavior of current traffic, and uses the temporal deployment of these combined types as the final input features for detecting attacks in real time as well as accurate detection. We construct the experimental environment for the data acquisition and analysis the performance of the proposed system against obtained data set.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1349-1354
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• 2021

An All-in-one LED lantern is a light device to determine the fairway of ships in operation. The current all-in-one LED lantern powered by solar energy is challenged by insufficient power capacity due to limited sun hours. This article presents an all-in-one 9-Nautical mile LED lantern driven by solar and wind power that is abundant maritime renewable energy. Furthermore, the remote smart monitoring system is developed. A smart control system capable of remote control of the lantern was implemented by using the LED lantern device and monitoring system as IoT. This technology that realtime condition monitoring and remote control are developed for safe ship navigation. We expect that maintaining the accuracy and consistency of LED lanterns prevents marine accidents and reduces social costs.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1105-1112
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• 2022

Field data monitoring systems such as renewable energy generation and smart farm integrated control are developing from PC and server to mobile first, and various wireless communication and application services have emerged with the development of IoT technology. Low-power wide-area networks are services optimized for low-power, low-capacity, and low-speed data transmission, and data collected in the field is transmitted to designated storage servers or cloud-based data platforms, enabling data monitoring. In this paper, we implement an IoT repeater that collects field data with a single device and transmits it to a wireless carrier cloud data flat using a low-power wide-area network, and a monitoring app using it. Using this, the system configuration is simpler, the cost of deployment and operation is lower, and effective data accumulation is possible.

• Plant Journal
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• v.18 no.3
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• pp.28-40
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• 2022

As the proportion of renewable energy generation is expected to increase, public power generation businesses need to actively consider implementing the expansion of biomass mixing, In this study, the biomass co-firing rate is being changed from 0wt.% to 5.0wt.% at 500MW coal-fired power plant, measuring the major operation characteristics of the pulverizer. First, the composition analysis and grinding characteristics of lignocelluosic biomass were examined, and the effect of volume increase on dirrerential bowl pressure difference, motor current, coal spillage, outlet temperature, and internal fire count was analyzed. As the co-firing rate increased, it was confirmed that the difference in the differential bowl pressure, motor current, and coal spillage treated increased, and the outlet temperature was minimal. The number of internal fires is difficult to find a clear correlation, but it has been confirmed that it is highly likely to occur in combination with other driving factors.

• Plant Journal
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• v.18 no.2
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• pp.41-45
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• 2022

The conventional communication method using mud flow pressure waves has a speed of 1-2 bps, so it takes a long time to communicate, making real-time control impossible. Although the sound wave communication method for improving the communication speed by 10 times or more has been commercialized, its use is limited due to its high price and there are not many application cases. In this study, the simulator corresponding to the facility was developed to develop performance similar to the actual test results. For simulating sound wave communication through a drill pipe, we proposed a governing equation that can simulate friction damping by mud and developed a numerical analysis model. The attenuation factor was corrected by comparing it with the attenuation rate of sound wave energy at the drilling site. The developed numerical analysis model was applied to the QPSK modulation type communication algorithm to confirm the excellent performance of the communication error rate of 0.04% in the ground. This is the communication performance under the condition that noise has not been mixed yet, and in order to apply it, the technology of reproducing the actual noise signal for mixing by securing the field noise data was established.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.361-369
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• 2022

Countries worldwide are shifting to a hydrogen economy to respond to stringent environmental regulations, and the transport of hydrogen between countries is expected to increase in the mid- to long-term. Hydrogen is traded between countries in different forms, such as ammonia, liquid hydrogen, and LOHC (Liquid Organic Hydrogen Carrier), on account of the renewable energy resources in exporting countries, the type of hydrogen use in importing countries, and the technological maturity; however, it is not traded only in a singular form. As marine transportation of ammonia and LOHC is a relatively mature technology compared to that of liquid hydrogen, in this article, we analyzed the technical feasibility of liquid hydrogen carriers while identifying detailed technologies required for their future development and securing possible designs through various technical alternatives.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.171-176
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• 2022

The communication signal for quick cut-off specification is defined as "design to support fast cut-off requirements of all applicable photovoltaic(PV) systems" in NEC 2014, NEC 2017 or the corresponding UL standard regardless of the system configuration. On the other hand, if you look at the domestic regulations related to new and renewable energy, the standards, regulations, and guidelines set by each institution are general, or only the parts necessary for the institution are being established and operated. There are many insufficient points to apply these things to photovoltaic facilities, and there are cases where excessive facilities are installed according to the design, inspection standards of supervisors and inspection agencies, and the skill level of inspectors. The internationally accepted IEC standards deal with various facility standards in detail. In each European country, there are separate facility regulations based on IEC. In particular, the performance and safety of devices are dealt with in detail, and in the case of 'NEC Article 690' applied in North America such as the United States, each item is described in detail. Therefore, in this paper, we will look at the details of the PV shutdown technology that is currently used and applied internationally.

• Journal of the Korean Geotechnical Society
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• v.26 no.2
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• pp.33-43
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• 2010

Geothermal energy is gaining wide attention as a highly efficient renewable energy and being increasingly used for heating/cooling systems of buildings. The standing column well (SCW) is especially efficient, cost-effective, and suitable for Korean geological and hydrological conditions. However, a numerical model that simulates the SCW has not yet been developed and applied in Korea. This paper describes the development of the SCW numerical model using a finite-volume analysis program. The model, through hydro-thermal coupled analyses, simulates heat transfer through advection, convection, and conduction. The accuracy of the model was verified through comparisons with field data measured at SCWs in the U.S. and Korea. Comparisons indicated that the SCW numerical model can closely predict the performance of a SCW. The numerical model was used to perform a comprehensive parametric study in the companion paper.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.33-41
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• 2023

Recently, global warming has accelerated climate change, increased extreme weather phenomena, and increased the frequency and intensity of weather disasters, leading to increasing uncertainty about the power production of new and renewable energy that is sensitive to weather. In fact, it has been reported that a number of damage to hydroelectric power generation have occurred due to weather disasters. Therefore, using the hydroelectric power generation performance data of Chungju Dam, meteorological data of Chungju Meteorological Observatory, and operation data of Chungju Dam, this study investigated the effect of meteorological disasters on hydroelectric power generation through structural equation modeling considering the number and intensity of meteorological disasters per month. The results indicated that the increased drought occurrence affected the decreased hydroelectric power generation by about 38.3 %, however the increased hydroelectric power generation could not explained by the increased flood occurrence. In conclusion, an increased drought occurrence in future may significantly influence hydroelectric power generation.

• Journal of the Korean Electrochemical Society
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• v.26 no.4
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• pp.64-70
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• 2023

Global warming is getting worse since a dramatic increase in greenhouse gas emissions recently. As a result, the necessity and implementation of carbon neutrality is required more urgently. To do this, among various new and renewable energies, attention in hydrogen arises. Hydrogen as a carbon-free power source is an abundant resource on Earth and is eco-friendly. Eventually, perfectly eco-friendly hydrogen can be obtained through electrolysis of water. However, the catalyst used in the oxygen evolution reaction is rare and expensive, and has a durability issue. Consequently, the development of a non-precious metal catalyst is necessary. In this review paper, we summarize and introduce Co- and Mo- based catalysts among recently announced oxygen evolution catalysts. This will help understand the design of catalyst to increase the activity and durability of non-precious metal catalysts.