• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.3
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• pp.10-17
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• 2017

The analytical modeling has been established on the self-propagation of intermetallic reaction in the spanwise direction of highly reactive boron and titanium nanoscale multilayers. Assuming that the reaction obeys Arrhenius kinetics, two-dimensional computations are carried out for heat and atomic species diffusion with exothermic reaction model in order to simulate the self-propagation of intermetallic reaction. The effects of bimetallic layer thickness and thickness ratio on the reaction propagation speed are tested and discussed in addition to the assessment of pre-mixing zone effects.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.395-403
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• 2011

Various studies were performed for providing the latest spatio-temporal information in mobile GIS Environments. The two-way synchronization scheme collects updated spatio-temporal data in the field and synchronizes with a server by using the wireless network. However, the other mobile terminals have to perform periodically synchronizes with a server. In this paper, we propose the update propagation scheme about spatio-temporal data collected from the mobile terminal. The update propagation scheme does considering various factors where an influence is in the update propagation. Therefore, it provides various update propagation policies according to each factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1796-1802
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• 2011

In this paper, the radio propagation path loss prediction simulator in tunnel was developed. It used a image theory method for analysing precise radio propagation path. And it can predict radio propagation path loss in straight and curved tunnels. The simulator can plot realtime radio propagation paths using various parameters which was input by user. And it can simulate from changing transmitter and receiver positions. The predicted path loss of simulator was compared with the measurements in Chunhyun tunnel and confirmed the validity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.985-996
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• 2012

An unsteadily propagating permeable crack in piezoelectric materials (PMs) under anti-plane shear mechanical loading and in-plane electric loading is studied. The equilibrium equations for a transiently propagating crack in a PM are developed, and the solutions on the stress and displacement fields for a permeable crack though an asymptotic analysis are obtained. The influences of piezoelectric constant, dielectric permittivity, time rate of change of the crack tip speed and time rate of change of stress intensity factor on the stress and displacement fields at the transiently propagating crack tip are explicitly clarified. By using the stress and displacements, the characteristics of the stress and displacement at a transiently propagating crack tip in a PM are discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.16-23
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• 2013

An experimental study has been conducted to investigate the effects of equivalence ratio on the propagation characteristics of $CH_4$-air premixed flame intervened by an ultrasonic standing wave. A Schlieren photography was used for the flame structure visualization, and the flame propagation behavior was investigated in detail throughout the post-processing analysis. It is found that the structural variation of methane/air premixed flame caused by the intervention of ultrasonic standing wave give rise to the enhancement of combustion reaction and flame propagation velocity. Effectiveness of the standing wave on the flame velocity decreases as the equivalence ratio increases. Larger flame velocity with the standing wave becomes undistinguishable in a specific range of equivalence ratios.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.393-398
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• 2022

During the test operation period of the wind profiler prototype, radio frequency interference (RFI) contamination occurred in the spectrum. The reference of the RFI that removed the algorithm appearing in the wind profiler spectrum were investigated, and a new algorithm was developed to remove the RFI. First, it was filtered with a threshold value of 0.1 m/s of the spectral width, and the range of the number of gates with the same radial velocity was determined according to whether the beam was a vertical beam or an oblique beam. RFI contamination was removed through filtering and scanning of non-weather signals, and the continuity of wind vectors calculated from the improved spectral radial velocity was verified.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.20-27
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• 2022

Present modeling study of nanoenergetics focuses on the numerical simulation of reaction wave propagation in normal direction across nanoscale multilayers of aluminum and nickel combination. The governing equations for atomic and thermal diffusion are employed in one-dimensional semi-infinitely alternating Al/Ni multilayered structures and the numerical results show the established patterns of quasi-steady intermetallic reaction waves. Also, the reaction wave speed is confirmed to be highly independent of reaction wave directions in such nanoenergetic structures.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.669-672
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• 2011

최근 IT(Information Technology)와 타(他)산업 간의 융 복합이 촉진되면서 새로운 융합서비스로 사물지능 통신(M2M, Machine to Machine)이 차세대 지능형 인프라 기반의 핵심 서비스로 부각되고 있다. 사물지능 통신은 기존의 통신 인프라를 활용하여 사물정보의 수집, 가공, 처리를 통해 최종 서비스를 제공하는 기술 분야로 PHY, MAC, 라우팅에 대한 기술 이슈보다는 서비스 관점에서의 네트워크 아키텍처 정의와 기능, 서비스 플랫폼 간의 연동, M2M 단말과 네트워크 간의 인터페이스에 대한 연구가 진행 중이다. 본 논문에서는 사물지능통신 융합서비스를 사용자에게 보다 편리하게 제공하기 위한 기존 플랫폼 간의 연동을 위한 요구사항과 방안을 제안한다.

• Economic Analysis
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• v.25 no.4
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• pp.25-57
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• 2019

This paper studies localization effects of knowledge spillovers in Korea using U.S. patents granted over the period 1996-2015. The "sample-matching" analysis initiated by Jaffe, Trajtenberg, and Henderson (1993) is adopted. We do not find evidence of positive localization effects in Korea. In particular, controlling for the existing geographic distribution of knowledge production, the frequency of domestic citations of Korean patents is no more than the citation frequency from overseas, and the difference is decreasing within the sample period. We also examine localization effects across regions and industries, and compare Korea with Taiwan and Japan.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.160-164
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• 2000

In this paper, we studied the relation between using amount of Ferrite and electromagnetic wave absorbing properties of ferrite-rubber composite. The variation of using amount of Ferrite have been 52 wt.% ~ 62 wt.%. As s result, it has been shown that the electromagnetic wave absorbing properties of ferrite-rubber composite are related to the using amount of Ferrite in composite. And, we can control electromagnetic wave absorbing properties of ferrite-rubber composite by the control of using amount of Ferrite.