• Proceedings of the KSME Conference
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• 2002.08a
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• pp.783-786
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• 2002

The unsteady turbulent flow characteristics of NACA4406 airfoil at close proximity to the pound are numerically investigated, especially focused on the noise generation mechanism near the blunt trailing edge. The unsteady two-dimensional compressible Wavier-Stokes equations with a Spalart-Allmaras turbulence closure model are solved by the 6th-order compact scheme and the 4th-order Runge-Kutta scheme. The computation shows a noise generation by a feedback mechanism at the blunt tailing edge, where the acoustic-fluidic coupling occurs between the wall-reflected sound waves and the periodically disturbed turbulent shear layer.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.445-450
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• 2012

BIPV/T (Building Intergrated PhotoVoltaic/Thermal) is combined system produces electricity and thermal energy. The heat from PV modules should be removed for better electrical performance, and can be converted into useful thermal energy. The efficiency of the PV system's performance will raise by the system removes heat from the PV. The test system is installed to top floor of the experimental house in the KEPCO Research Institute. The planned experiment is following. (1) Supplying heat energy to top floor. (2) Supplying heat and cool energy to thermal storage in the bottom of the top floor. (3) Supplying heat energy to EHP for improved performance. The experimental performance is executed from 13th February to 13th March, 2012. The solar generation of electricity is 4.04kWh under the horizontal solar radiation is $1000W/m^2$ and the air temperature is $25^{\circ}C$.

• International Journal of Advanced Culture Technology
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• v.12 no.2
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• pp.30-35
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• 2024

With the recent commercialization of the 5th generation mobile communication technology (5G), interest is focused on full-fledged wireless communication service products in related industries that apply the technology. In this paper, "the problems of the cloud-based video game streaming service market, which has been stagnant for a long time due to the existing 4G-based transmission delay, processing delay, and price issues, and the problems of 5G mobile communication, which began commercialization in 2019." We contains information about what type of positive changes a cloud-based video game streaming service incorporating technology will bring.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1190-1191
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• 2004

New $4^{th}$ generation synchrotron facility, XFEL, is almost similar to previous $3^{rd}$ generation synchrotron facility in the view of radiological aspects and most important positions are a dump and synchrotron radiation beam line. In this paper, tile radiation protection solutions for them and undulator are suggested and discussed.

• The Korean Journal of Ecology
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• v.22 no.1
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• pp.31-37
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• 1999

The developmental process of Paracolopha morrisoni's galls on Zelkova serrata until the emergence of alatae from the galls was studied at Chonju, Korea. The galls were formed from late April to early May, 1997 and the galls began to open in early June. The length and width of galls and leaves were measured during the period from gall formation to opening. The length and width of galls have been increased until mid May continuously. The galls stopped growing at 12th of May. Fundatrices (the first generation in the gall) began to larviposit from May 15th and the second generation developed in late May. The alatae of the second generation arrived at the final stadium, that was escaped from the gall, in early June. Thus, there were only 2 generations in the gall. The close correlationship between gall growth and leaf growth suggests that leaf growth force may have a great influence on gall development.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.10
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• pp.652-658
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• 2016

Thermal batteries use inorganic salt as electrolyte, which is inactive at room temperature. As soon as heat pellets are fired by an igniter, all the solid electrolytes are instantly melted into excellent ionic conductors. However, the abnormal heat generation by the igniter flame or heat pellets causes the thermal decomposition of the electrode and the melting of the anode, eventually leading to a thermal runaway, which results in overheating or explosion. The thermal runaway can be significantly reduced by the adoption of $Zr/BaCrO_4$ heat papers. In this study, the heat papers with various ratios of fuel (Zr) and oxidizer ($BaCrO_4$) were prepared by the paper-making process. We have investigated the calorimetric value, burning rate, and ignition sensitivity. The ignition test of heat pellets and the discharge test of thermal batteries were also carried out. At the composition of 40 wt.% of Zr, the heat papers showed the highest specific calorimetric value and burning rate. As a result, $Zr/BaCrO_4$ heat paper made by the paper-making process has shown the applicability for thermal batteries.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.436-447
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• 2014

The major elements of avionics system architecture are requirements, Real Time Operating System, message communication, memory, and data format etc. Herein describes a state-of-the-art development trend for the avionics system architecture, system requirements and data bus among the major elements of avionics system. While, domestic technology has been tried to Integrated Modular Avionics(IMA) system based on the Avionics Full Duplex Switched Ethernet(AFDX) technology during Light Attack Helicopter(LAH) project in Korea, but not yet proved as the product case in Full Scale Development Phase. The avionics system architecture considering the domestic inexperience of the IMA system architecture are suggested for the Next-generation Corps Unmanned Aircraft System.

• Journal of the Korea Convergence Society
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• v.12 no.7
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• pp.193-205
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• 2021

The AI speaker market is growing steadily. However, the satisfaction of actual users is only 42%. Therefore, in this paper, we collected reviews on Amazon Echo Dot 3rd and 4th generation models to analyze what hinders the user experience through the topic changes and emotional changes of each generation of AI speakers. By using topic modeling analysis techniques, we found changes in topics and topics that make up reviews for each generation, and examined how user sentiment on topics changed according to generation through deep learning-based sentiment analysis. As a result of topic modeling, five topics were derived for each generation. In the case of the 3rd generation, the topic representing general features of the speaker acted as a positive factor for the product, while user convenience features acted as negative factor. Conversely, in the 4^th generation, general features were negatively, and convenience features were positively derived. This analysis is significant in that it can present analysis results that take into account not only lexical features but also contextual features of the entire sentence in terms of methodology.

• Journal of IKEEE
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• v.25 no.4
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• pp.766-769
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• 2021

In order to perform tasks such as design, control, optimization, and prediction of flight vehicle trajectories based on machine learning techniques including deep learning, a certain amount of flight vehicle trajectory data is required. However, there are cases in which it is difficult to secure more than a certain amount of flight vehicle trajectory data for various reasons. In such cases, synthetic data generation could be one way to make machine learning possible. In this paper, to explore this possibility, we generated and evaluated synthetic flight vehicle trajectory data using time-series generative adversarial neural network. In addition, various ablation studies (comparative experiments) were performed to explore the possibility of using synthetic data in the aircraft trajectory prediction task. The experimental results presented in this paper are expected to be of practical help to researchers who want to conduct research on the possibility of using synthetic data in the generation of synthetic flight vehicle trajectory data and the work related to flight vehicle trajectories.

• The Journal of Society for e-Business Studies
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• v.24 no.2
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• pp.91-112
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• 2019

In accordance with the advent of the 5th generation (5G) communication technology, we are having a change in various communication services which converge with high technologies related to the 4th Industrial Revolution. To utilize the upcoming 5G technology effectively and practically, we analyzed the technologies which have the most potential in convergence under the introduction of 5G technology and as a result, it is a autonomous vehicle that we'll discuss the core technologies of the 4th Industrial Revolution, which can lead to service activation by being combined with 5G technology. In addition, we developed an industry-service classification of 5G-based autonomous vehicle, we provided a basis for supporting a new business and its new business model converged with 5G communication technology. Furthermore, we will create a linkage matrix with the industry-service classification system of a new autonomous vehicles. This matrix will service as a guideline for industry-service development where autonomous vehicles can be utilized actively in the next generation.