• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.648-656
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• 2022

As environmental regulations such as the International Maritime Organization (IMO)'s strategy to reduce greenhouse gases(GHG) are strengthened, technology development such as eco-friendly ships and alternative fuels is expanding. As part of this, ship propulsion technology using energy reduction and wind propulsion technology is emerging, especially in shipping companies and shipbuilders. By securing wind propulsion technology and introducing empirical research into shipbuilding and shipping, a high value-added market using eco-friendly technology can be created. Moreover, by reducing the fuel consumption rate of operating ships, GHG can be reduced by 6-8%. Rotor Sail (RS) technology is to generate a hydrodynamic lift in the vertical direction of the cylinder when the circular cylinder rotates at a constant speed and passes through the fluid. This is called the Magnus effect, and this study attempted to propose a plan to increase propulsion efficiency through a numerical analysis study on turbulence flow characteristics around RS, a wind power assistance propulsion system installed on a ship. Therefore, C_L and C_D values according to SR and AR changes were derived as parameters that affect the aerodynamic force of the RS, and the flow characteristics around the rotor sail were compared according to EP application.

• Journal of the Korea Society of Computer and Information
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• v.29 no.8
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• pp.157-164
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• 2024

In this paper, we propose a discussion that the feasibility of deploying a deep learning-based detector on the resource-limited board. Although many studies evaluate the detector on machines with high-performed GPUs, evaluation on the board with limited computation resources is still insufficient. Therefore, in this work, we implement the deep-learning detectors and deploy them on the compact board by parsing and optimizing a detector. To figure out the performance of deep learning based detectors on limited resources, we monitor the performance of several detectors with different H/W resource. On COCO detection datasets, we compare and analyze the evaluation results of detection model in On-Board and the detection model in On-GPU in terms of several metrics with mAP, power consumption, and execution speed (FPS). To demonstrate the effect of applying our detector for the military area, we evaluate them on our dataset consisting of thermal images considering the flight battle scenarios. As a results, we investigate the strength of deep learning-based on-board detector, and show that deep learning-based vision models can contribute in the flight battle scenarios.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.143-150
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• 2012

A simulation methodology and corresponding program based on it is to be discussed for analyzing the effects of the networking operation of existing DHC system in connection with CHP system on-site. The practical simulation for arbitrary areas with various building compositions is carried out for the analysis of operational features in both systems, and the various aspects of thermal energy grids with connecting operation are highlighted through the detailed assessment of predicted results. The intrinsic operational features of CHP prime movers, gas engine, gas turbine etc., are effectively implemented by realizing the performance data, i.e. actual operation efficiency in the full and part loads range. For the sake of simplicity, a simple mathematical correlation model is proposed for simulating various aspects of change effectively on the existing DHC system side due to the connecting operation, instead of performing cycle simulations separately. The empirical correlations are developed using the hourly based annual operation data for a branch of the Korean District Heating Corporation (KDHC) and are implicit in relation between main operation parameters such as fuel consumption by use, heat and power production. In the simulation, a variety of system configurations are able to be considered according to any combination of the probable CHP prime-movers, absorption or turbo type cooling chillers of every kind and capacity. From the analysis of the thermal network operation simulations, it is found that the newly proposed methodology of mathematical correlation for modelling of the existing DHC system functions effectively in reflecting the operational variations due to thermal energy grids with connecting operation. The effects of intrinsic features of CHP prime-movers, e.g. the different ratio of heat and power production, various combinations of different types of chillers (i.e. absorption and turbo types) on the overall system operation are discussed in detail with the consideration of operation schemes and corresponding simulation algorithms.

• Journal of Life Science
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• v.18 no.3
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• pp.291-297
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• 2008

We investigated whether 1) the combined capsaicin (75 mg), sesamin (30 mg), and L-carnitine (900 mg) (CCSC) ingestion enhances autonomic nervous system (ANS) activities including thermogenic sympathetic activity as energy metabolic modulator, 2) ${\beta}_3-AR$ polymorphism of each subject influences with ANS activity. Seven healthy males $(22.0{\pm}0.5\;yr)$ volunteered for this study. The cardiac autonomic nervous activities evaluated by means of heart rate variability of power spectral analysis were continuously measured during 5 min every 30 min for total 120 min resting condition with CCSC or placebo oral administration chosen at random. The results indicated that, there are not $Arp/Arg^{64}$ variants of the ${\beta}_3-AR$ genotypes in our subjects. There were not also significant differences in heart rate during rest between both trials. The difference of ANS activity did not reach the statistical significance between both trials. However, the significant improvement showed TOTAL power, HF component, and the indices of SNS and PNS activities before and at 30 min after CCSC ingestion (p<0.05, respectively). In conclusions, although each component of combined CCSC is associated with lipolysis and/or fat oxidation, the combined CCSC consumption is not influenced in stimulation of thermogenic sympathetic activity as modulator of energy metabolism. In rather, our results suggested that CCSC ingestion improves the balance of both SNS and PNS activities. Therefore, it will be considered many combined nutrient components for ergogenic and/or lipolysis effects as well as genetic variants affecting ANS activity in further studies.

• Journal of Science Education
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• v.45 no.3
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• pp.292-303
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• 2021

This study identifies the terms frequently used together with energy in online science news articles and topics of the news reports to find out how the term energy is used in everyday life and to draw implications for science curriculum and instruction about energy. A total of 2,171 online news articles in science category published by 11 major newspaper companies in Korea for one year from March 1, 2018 were selected by using energy as a search term. As a result of natural language processing, a total of 51,224 sentences consisting of 507,901 words were compiled for analysis. Using the R program, term frequency analysis, semantic network analysis, and structural topic modeling were performed. The results show that the terms with exceptionally high frequencies were technology, research, and development, which reflected the characteristics of news articles that report new findings. On the other hand, terms used more than once per two articles were industry-related terms (industry, product, system, production, market) and terms that were sufficiently expected as energy-related terms such as 'electricity' and 'environment.' Meanwhile, 'sun', 'heat', 'temperature', and 'power generation', which are frequently used in energy-related science classes, also appeared as terms belonging to the highest frequency. From a network analysis, two clusters were found including terms related to industry and technology and terms related to basic science and research. From the analysis of terms paired with energy, it was also found that terms related to the use of energy such as 'energy efficiency,' 'energy saving,' and 'energy consumption' were the most frequently used. Out of 16 topics found, four contexts of energy were drawn including 'high-tech industry,' 'industry,' 'basic science,' and 'environment and health.' The results suggest that the introduction of the concept of energy degradation as a starting point for energy classes can be effective. It also shows the need to introduce high-tech industries or the context of environment and health into energy learning.

• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.1-11
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• 2011

Many researchers have studied on the methods to improve the processor performance. However, high integrated semiconductor technology for improving the processor performance causes many problems such as battery life, high power density, hotspot, etc. Especially, as hotspot has critical impact on the reliability of chip, thermal problems should be considered together with performance and power consumption when designing high-performance processors. To alleviate the thermal problems of processors, there have been various researches. In the past, mechanical cooling methods have been used to control the temperature of processors. However, up-to-date microprocessors causes severe thermal problems, resulting in increased cooling cost. Therefore, recent studies have focused on architecture-level thermal-aware design techniques than mechanical cooling methods. Even though architecture-level thermal-aware design techniques are efficient for reducing the temperature of processors, they cause performance degradation inevitably. Therefore, if the mechanical cooling methods can manage the thermal problems of processors efficiently, the performance can be improved by reducing the performance degradation due to architecture-level thermal-aware design techniques such as dynamic thermal management. In this paper, we analyze the cooling efficiency of high-performance multicore processors according to mechanical cooling methods. According to our experiments using air cooler and liquid cooler, the liquid cooler consumes more power than the air cooler whereas it reduces the temperature more efficiently. Especially, the cost for reducing $1^{\circ}C$ is varied by the environments. Therefore, if the mechanical cooling methods can be used appropriately, the temperature of high-performance processors can be managed more efficiently.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.204-215
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• 2020

We analyze changes of consumption behavior for bundle services for the latest three years focusing on comparing the detailed service types and service providers to understand competition structure in the market. Our major findings and implications are as follows. First, the mobile telecommunication service is certainly deemed to be a major selection criteria for bundling service provider, therefore the leading company in the mobile telecommunication has become more significant market power. Second, IPTV has an important influence for slection of bundling service provider, lately in some cases, rather than broadband Internet. Third, the individual services affecting the selection of bundling service providers clearly showed differentiation among three operators as a mobile telecommunication service of SK Group, a broadband Internet of KT, and an IPTV of LGU+. In addition, the importance of individual services in securing subscribers has been increased as the preference factors to switch a service provider were synchronized with the decision of major bundling service provider. Finally, although it is difficult to find customers' lock-In due to the latest change of their intentions to switch a provider, we find it is continuously necessary to monitor customers' lock-in as there are more long-term customers with re-contracts. Our results provide the policy implications based on the change of competition structure and usage behavior in the bundle market which is not evaluated the competiton situation.

• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1199-1205
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• 2017

Global energy consumption is rapidly increasing yearly due to drastic industrial advances, requiring the development of new energy storage devices. For this reason, supercapacitors with fast charge-discharge, long life cycle and high power density is getting attention, and have been considered as one of the potential energy storage systems. In this research, we developed a supercapacitor that consists of amorphous manganese oxide($MnO_2$) electrodes deposited onto carbon cloth substrates using the hydrothermal method. The Fe-doped amorphous $MnO_2$ samples were characterized by X-ray diffraction(XRD), Energy Dispersive X-ray spectroscopy(EDX), as well as scanning electron microscopy(SEM). The electrochemical analysis of the prepared samples were performed using cyclic voltammetry and galvanostatic charge-discharge measurements in 1M $Na_2SO_4$ electrolyte. The test results demonstrate that the supercapacitor based on the Fe-doped amorphous $MnO_2$ electrodes has a specific capacitance as high as 163F/g at 1A/g current density, and good cycling stability of 87.34% capacitance retention up to 1000 cycles.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.159-166
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• 2013

Recently, because the interest and needs in privacy protection are growing, smartcard-based remote user authentication schemes have been actively studied to provide the user anonymity. In 2008, Kim et al. first proposed an authentication scheme in order to ensure the user anonymity against both external attackers and the remote server and track malicious users with the help of a trusted trace sever. However, in 2010, Lee et al. showed that Kim et al.'s scheme cannot provide the user anonymity against remote server, which is because the server can trace users without any help of the trace server, and then proposed a improved scheme. On the other hand, in 2010, Horng et al. proposed an authentication scheme with non-tamper resistant smart cards, in which the non-tamper resistant smart card means that an attacker may find out secret information stored in the smart card through special data analysis techniques such as monitoring power consumption, to be secure against a variety of attacks and to provide the user anonymity against external attackers. In this paper, we will propose a remote user authentication scheme with non-tamper resistant smart cards not only to ensure the user anonymity against both external attackers and the remote server but also to track malicious users with only the help of a trusted trace sever.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.3
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• pp.78-87
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• 2013

NAND flash memory has been widely used as a storage medium in mobile devices, PCs, and workstations due to its advantages such as low power consumption, high performance, and random accessability compared to a hard disk drive. However, NAND flash cannot support in-place update so that it is mandatory to erase the entire block before overwriting the corresponding page. In order to overcome this drawback, flash storages need a software support, named Flash Translation Layer. However, as the high performance mass NAND flash memory is getting widely used, the size of mapping tables is increasing more than the limited DRAM size. In this paper, we propose an adaptive mapping information caching algorithm based on page mapping to solve this DRAM space shortage problem. Our algorithm uses a mapping information caching scheme which minimize the flash memory access frequency based on the analysis of several workloads. The experimental results show that the proposed algorithm can increase the performance by up to 70% comparing with the previous mapping information caching algorithm.