• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.17-23
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• 2020

Upper stage of launch vehicle mainly injects a lunar explorer from low earth orbit to the moon at a distance of 380,000 km. In foreign lunar explorer, the upper stage is separated from the explorer after the explorer is injected into the earth-moon transfer trajectory, and the lunar explorer then uses on-board propellant to carry out mid-course correction maneuvers and lunar orbit insertion maneuvers. This study describes a newly presented small liquid upper stage. Using a small liquid upper stage with a wet mass of 2.9 tonnes, the lunar explorer not only can be injected earth-moon transfer trajectory but also can be performed lunar orbit insertion. This study provides acceptable mass range of the lunar explorer and the scope of acceptable mission range also describes based on the launch from Naro Space Center.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.2
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• pp.97-103
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• 2015

This paper has focused on the middle term process planning around quays based on the prefixed long-term plan of the product mixed ships. Recently, the order rate of high add-value ships in domestic shipyards has been sharply increased and the spending time at quays is accordingly on an increasing trend. For proper and practical process planning related to quays, it has to be closely connected with a long-term plan and product calendar, erection network and result of ship allocation around quays. Moreover, it is also required to include the integrated consideration of the whole process of a yard, each ship, and each team respectively. The most distinguishing feature of this study is that it would run on the ship allocation simulator and GIS framework in order not to be limited to the specific one yard and the readers can figure out the optimization formulation containing the work load leveling and a different approach from PERT/CPM. The proposed approach reflected all requirements from the department of process planning and management in a shipyard, and the analysis of the results has explained its performance of the optimization result with the examples of total 43 ships under construction from 2008 to 2013.

• YAKHAK HOEJI
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• v.54 no.2
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• pp.142-149
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• 2010

Development of alternative testing methods for the replacement of hazardous reagents with less hazardous ones is strongly enforced because exposure of human and environment to hazardous reagents are restricted and hazardous reagents are gradually prohibited from using in various testing methods. Thus, in this study, we developed 8 monographs from the Korean Pharmaceutical Codex by substituting the use of the hazardous reagents including ICH class 1 such as benzene, chloroform and dioxane to the use of less toxic ones like ICH class 2 or 3 reagents. We also improved their qualification and quantification performance. Among 8 monographs, the 6 newly developed TLC methods for the identification of nifedipine, oxolamine citrate, ketoprofen lysinate, chlorquinaldol, retinol acetate, and riboflavin showed a clear spot of corresponding material without any interference in spite of the replacement with ICH class 2 or 3 reagents. For the quantification of domperidone and trimebutine, HPLC methods were developed for the substitution of UV/VIS spectrometry and titrimetry, respectively. These HPLC methods were validated for the linearity, recovery, reproducibility, and inter-laboratory variations. In conclusion, the newly developed methods could be expected to become valuable tools for revising the Korean Pharmaceutical Codex.

• Magazine of the Korea Concrete Institute
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• v.20 no.6
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• pp.28-35
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• 2008

The Burj Dubai Project will be the tallest structure ever built by man; when completed the tower will be more than 700 meter tall and more than 160 floors. While the early integration of aerodynamic shaping and wind engineering considerations played a major role in the architectural massing and design of this multi-use/residential tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria, the material selection for the structural systems of the tower was also a major consideration and required detailed evaluation of the material technologies and skilled labor available in the market at the time Concrete was selected for its strength, stiffness, damping, redundancy, moldability, free fireproofing, speed of construction, and cost effectiveness. In addition, the design challenges of using concrete for the design of the structural system components will be addressed. The focus on this paper will also be on the early planning of the concrete works of the Burj Dubai Project.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.60-66
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• 2015

Conjugate heat transfer analysis was performed to investigate the flow and cooling performance of the high pressure turbine nozzle of gas turbine engine. The CHT code was verified by comparison between CFD results and experimental results of C3X vane. The combination of k-${\omega}$ based SST turbulence model and transition model was used to solve the flow and thermal field of the fluid zone and the material property of CMSX-4 was applied to the solid zone. The turbine nozzle has two internal cooling channels and each channel has a complex cooling configurations, such as the film cooling, jet impingement, pedestal and rib turbulator. The parabolic temperature profile was given to the inlet condition of the nozzle to simulate the combustor exit condition. The flow characteristics were analyzed by comparing with uncooled nozzle vane. The Mach number around the vane increased due to the increase of coolant mass flow flowed in the main flow passage. The maximum cooling effectiveness (91 %) at the vane surface is located in the middle of pressure side which is effected by the film cooling and the rib turbulrator. The region of the minimum cooling effectiveness (44.8 %) was positioned at the leading edge. And the results show that the TBC layer increases the average cooling effectiveness up to 18 %.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.1 no.2
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• pp.4-18
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• 2002

In this paper, we propose the new design method for the OFDM based modem that is considerd a standard of wireless communication in indoor environments. We designed a improved FFT/IFFT in order to satisfy a data rate $6{\sim}54$Mbps required homenetworking of high speed and a improved channel equalization circuit using pilot signals for modile environments. And we designed a carrier offset estimator that uses the $tan^{-1}$ circuit to organize a memory structure. All steps are verifed performance through a FPGA and are implemented ASIC to use a standard library cell.

• Journal of KIISE:Software and Applications
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• v.31 no.12
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• pp.1569-1580
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• 2004

One commonly used approach to deal with uncertainty is Bayesian network which represents joint probability distributions of domain. There are some attempts to team the structure of Bayesian networks automatically and recently many researchers design structures of Bayesian network using evolutionary algorithm. However, most of them use the only one fittest solution in the last generation. Because it is difficult to combine all the important factors into a single evaluation function, the best solution is often biased and less adaptive. In this paper, we present a method of generating diverse Bayesian network structures through fitness sharing and combining them by Bayesian method for adaptive inference. In order to evaluate performance, we conduct experiments on learning Bayesian networks with artificially generated data from ASIA and ALARM networks. According to the experiments with diverse conditions, the proposed method provides with better robustness and adaptation for handling uncertainty.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7949-7956
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• 2015

This paper introduced the RAR(Reinforced Abutment for Railroads) to reduce settlement of transitional zone and horizontal displacement of abutment by constructing backfill before abutment. We expect that it has more economical and better performance which was validated by numerical analyses. First, transitional zone settlements and horizontal displacements of existing abutment were evaluated for various heights and ground conditions by using finite element analysis program. Then, numerical analyses of it under the same conditions were performed and its results were compared with existing abutment's ones. From the numerical analysis, we found that the responses(settlement and horizontal displacement) of transitional zone of the RAR is about 20% and 34% of one of existing abutment due to the effect of backfill stabilizing. We expected that the RAR having small foundations could be economic way to construct abutment with the control of responses such as, settlement, horizontal displacement, and earth pressure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.3
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• pp.595-603
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• 2017

We propose a scheme to reduce the time for the SSL/TLS handshake by embedding it into the TCP 3-way handshake. The scheme can be selectively applied on the standard TCP for making the SSL/TCP handshake happen within the TCP handshake, rather than performing the TCP handshake and SSL/TLS handshake in sequence. We implemented a prototype of the scheme and did some experiments on its performance. Experimental results showed that, compared to the sequential handshakes of the TCP and the SSL/TLS, the time reduction achieved by the scheme varied in the range of 3.2% and 14%(when the elapsed time by the ping program from the client to the server was 11.6ms). The longer the time measured by the ping program, which would grow as the propagation and queuing delays do, the larger the reduction rate. It accords with the supposition that the reduced time due to the scheme will increase in proportion to the amount of the elapsed time measured by the ping program.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.231-237
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• 2018

In this study, two important requirements for the home production of a robot to detect and remove improvised explosive devices (IEDs) are presented in terms of the total cost for robot system development and the performance improvement of the mine detection technology. Firstly, cost analyses were performed in order to provide a reasonable solution following an engineering estimate method. As a result, the total cost for a mass production system without the mine detection system was estimated to be approximately 396 million won. For the case including the mine detection system, the total cost was estimated to be approximately 411 million won, in which labor costs and overhead charges were slightly increased and the material costs for the mine detection system were negligible. Secondly, a method for fabricating the carbon nanotube (CNT) based gas detection sensor was studied. The detection electrodes were formed by a photolithography process using a photosensitive CNT paste. As a result, this method was shown to be a scalable and expandable technology for producing excellent mine detection sensors. In particular, it was found that surface treatments by using adhesive taping or ion beam bombardment methods are effective for exposing the CNTs to the ambient air environment. Fowler-Nordheim (F-N) plots were obtained from the electron-emission characteristics of the surface treated CNT paste. The F-N plot suggests that sufficient electrons are available for transport between CNT surfaces and chemical molecules, which will make an effective chemiresistive sensor for the advanced IED detection system.