• Title/Summary/Keyword: Propagation time

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Modeling of Electromagnetic Wave Propagation for Detection of Bond Delamination in Concrete (콘크리트 보강재 박리 검사를 위한 전자파 모델링)

  • 남연수;임홍철
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.17 no.3
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    • pp.261-269
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    • 2004
  • The existing concrete beams can be retrofitted or reinforced by attaching carbon fiber or glass fiber sheet beneath the beams. Although diverse design methods and application techniques of the retrofitting are studied and developed, the testing method of examining retrofitted beams have not been put into practice yet. In this study, a bond delamination has been modeled and studied to provide a basis for the development of actual testing equipments. For this purpose, Gaussian and sinusoidal waves with 3GHz and 5GHz center frequency are used as an incident wave and 1mm and 3mm bond delamination under the reinforcement are modeled. In the modeling, Finite Difference-Time Domain algorithm is used to investigate the behavior of electromagnetic waves in concrete. The results have shown that 5GHz waves are suitable for the detection of delamination.

[Retraction] A study on strategy for Korean education contents to enter the global market through popularization of Korean Wave ([논문철회] 한류의 대중화를 통한 한국 교육컨텐츠의 세계시장 진출전략 연구)

  • Park, Hyun-Kyu
    • Journal of Digital Convergence
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    • v.18 no.5
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    • pp.99-104
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    • 2020
  • It is needed to advance into the global market at the present time, which has the best educational contents along with the Korean Wave. In this study, an analysis was conducted to emphasize the necessity of entering educational contents into the global market, and in the necessity of disseminating educational contents and branding educational contents were approached. The strategies to enter the global market for educational contents are as follows; First, the government established a strategy for disseminating and using educational contents to expand overall cultural exchange with developing countries. Second, localization strategy for continuous growth of educational contents. Third, localization of contents and formation of partnership for local resistance, which is a response to unilateral propagation. Through the advancement of educational contents to the global market, it will be possible to sustain not only the positive effect on the national image, but also the economic effect that Korean Wave originally has.

Effect of Platform Screen Door on fire in the subway station (스크린도어가 설치된 지하철 승강장의 화재유동 전산 수치 모사를 이용한 스크린도어의 화재 영향 연구)

  • Jang, Yong-Jun;Jung, Woo-Sung;Park, Won-Hee;Kim, Hag-Beom
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1337-1345
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    • 2007
  • The present study is a basic investigation for systematically proceeding disaster prevention studying the effect of platform screen door in case of fire at the subway station. In the paper, the characteristics of screen door were surveyed and described. The fully closed platform screen door and the island type of subway station were employed for simulation-study. Numerical simulations of fire driven flow at the subway station with platform screen door were performed with commercial fire CFD code. For analyzing of the effect of platform screen door, the fire simulations with and without the platform screen door were compared. For the fire location, the one is located on the platform and the other case on the railway. The Ultrafast model was taken as fire growth scenario. The maximum heat release rate was 10MW. The propagated time of the heat and smoke to stairs was within 4 minute when the fire is located on the platform. However the heat and smoke propagation was block off by screen door when the fire is located on the railway.

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Analysis of Fukuoka Earthquakes Characterisics considering site amplification (관측소 부지증폭 특성을 고려한 후쿠오카 지진특성 연구)

  • Oh, Tae-Seok;Yoo, Seong-Hwa;Kim, Jun-Kyoung
    • 한국지구물리탐사학회:학술대회논문집
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    • 2006.06a
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    • pp.187-192
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    • 2006
  • The Korean peninsula has been considered as seismically intermediate region, since seismic activities have not been severe for long time and the active tectonic boundary is also located far away. However, the activities of earthquakes have been increased significantly for last decade. Since currently important structures and facilities are increasing rapidly in the Korean Peninsula, the importance of seismic design are increasing exponentially too. This study used observed ground motion of Fukuoka event including 11 afterschocks and then estimated seismic parameters representing seismic source, propagation effect, considering site amplification. The results were comparable to those of other studies in the same region. The results could be used as basic important parameters for seismic design of the important structures and facilities in Korean peninsula.

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Effects of Date and Growth Regulators on the Culture of' Immature Zygotic Embryos of North American Ginseng

  • Hovius, Marilyn H. Y.;Saxena, Praveen K.;Proctor, John T. A.
    • Journal of Ginseng Research
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    • v.31 no.1
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    • pp.14-22
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    • 2007
  • As the zygotic embryo of North American ginseng (Panax quinquefolius L.) matured during stratification over 203 days it grew from 0.75 to 5.2 mm. Embryo excision and culturing on media containing different concentrations of two growth regulators, gibberellic acid ($GA_3$, 1 to 10 ${\mu}M$) and benzyladenine (BA, 1 to 5 ${\mu}M$), during stratification, showed that shoot and root number and the shoot, root and cotyledon length increased with increased stratification time. Gibberellic acid was the more effective growth regulator for increasing shoot and root number and shoot, root and cotyledon lengths. Immature embryos (stratified for up to 63 days) needed growth regulators for further development. Cultures on $GA_3$ at the last culture date (stratified for 203 days) when embryos were mature, produced multiple shoots but there was no effect of $GA_3$ concentration. Benzyladenine inhibited shoot and root growth regardless of embryo stratification. Growth regulators had little effect on cotyledon length of mature embryos. Embryos cultured on $GA_3$ combined with BA were green on all culture dates whereas greening in the control and BA treatments increased with culture date. The BA treatments induced 100% swelling of the embryos on the final culture date while in the control and $GA_3$ treatments there was no swelling. There was little or no curling in the control and BA treatments and a linear decrease in curling with culture date in the $GA_3$ and $GA_3$ + BA treatments.

A Novel Redundant Data Storage Algorithm Based on Minimum Spanning Tree and Quasi-randomized Matrix

  • Wang, Jun;Yi, Qiong;Chen, Yunfei;Wang, Yue
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.1
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    • pp.227-247
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    • 2018
  • For intermittently connected wireless sensor networks deployed in hash environments, sensor nodes may fail due to internal or external reasons at any time. In the process of data collection and recovery, we need to speed up as much as possible so that all the sensory data can be restored by accessing as few survivors as possible. In this paper a novel redundant data storage algorithm based on minimum spanning tree and quasi-randomized matrix-QRNCDS is proposed. QRNCDS disseminates k source data packets to n sensor nodes in the network (n>k) according to the minimum spanning tree traversal mechanism. Every node stores only one encoded data packet in its storage which is the XOR result of the received source data packets in accordance with the quasi-randomized matrix theory. The algorithm adopts the minimum spanning tree traversal rule to reduce the complexity of the traversal message of the source packets. In order to solve the problem that some source packets cannot be restored if the random matrix is not full column rank, the semi-randomized network coding method is used in QRNCDS. Each source node only needs to store its own source data packet, and the storage nodes choose to receive or not. In the decoding phase, Gaussian Elimination and Belief Propagation are combined to improve the probability and efficiency of data decoding. As a result, part of the source data can be recovered in the case of semi-random matrix without full column rank. The simulation results show that QRNCDS has lower energy consumption, higher data collection efficiency, higher decoding efficiency, smaller data storage redundancy and larger network fault tolerance.

EEG Analysis for Cognitive Mental Tasks Decision (인지적 정신과제 판정을 위한 EEG해석)

  • Kim, Min-Soo;Seo, Hee-Don
    • Journal of Sensor Science and Technology
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    • v.12 no.6
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    • pp.289-297
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    • 2003
  • In this paper, we propose accurate classification method of an EEG signals during a mental tasks. In the experimental task, subjects achieved through the process of responding to visual stimulus, understanding the given problem, controlling hand motions, and select a key. To recognize the subjects' selection time, we analyzed with 4 types feature from the filtered brain waves at frequency bands of $\alpha$, $\beta$, $\theta$, $\gamma$ waves. From the analysed features, we construct specific rules for each subject meta rules including common factors in all subjects. In this system, the architecture of the neural network is a three layered feedforward networks with one hidden layer which implements the error back propagation learning algorithm. Applying the algorithms to 4 subjects show 87% classification success rates. In this paper, the proposed detection method can be a basic technology for brain-computer-interface by combining with discrimination methods.

Numerical Method for Prediction of Air-pumping Noise by Car Tyre (자동차 타이어의 Air-Pumping소음 예측을 위한 수치적 기법)

  • Kim, Sungtae;Jeong, Wontae;Cheong, Cheolung;Lee, Soogab
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.7 s.100
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    • pp.788-798
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    • 2005
  • The monopole theory has long been used to model air-pumped effect from the elastic cavities in car tire. This approach models the change of an air as a Piston moving backward and forward on a spring and equates local air movements exactly with the volume changes of the system. Thus, the monopole theory has a restricted domain of applicability due to the usual assumption of a small amplitude acoustic wave equation and acoustic monopole theory This paper describes an approach to predict the air-pumping noise of a car tyre with CFD/Kirchhoff integral method. The tyre groove is simply modeled as piston-cavity-sliding door geometry and with the aid of CFD technique flow properties in the groove of rolling car tyre are acquired.'rhese unsteady flow data are used as a air-pumping source in the next CFD calculation of full tyre-road geometry. Acoustic far field is predicted from Kirchhoff integral method by using unsteady flow data in space and time which is provided by the CFD calculation of full tyre-road domain. This approach can cover the non-linearity of acoustic monopole theory with the aid of Non-linear governing equation in CFD calculation. The method proposed in this paper is applied to the prediction of air-pumping noise of simply modeled car tyre and through the predicted results, the influence of nonlinear effect on air-pumping noise propagation is investigated.

Preference Analysis of Traffic Information Service Depending on Smart Phone Possession (스마트폰 보유여부에 따른 교통정보 제공 시스템의 선호도 분석)

  • HEO, Min;KIM, Hoe Kyoung
    • Journal of Korean Society of Transportation
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    • v.33 no.5
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    • pp.470-477
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    • 2015
  • VMS informs the public of traffic and weather information in real time and functions to facilitate traffic flow. However, as smart phone navigation becomes more popular with the rapid propagation of the smart phone, the efficiency and applicability of VMS are challenged. Accordingly, this study aims to investigate the drivers' preference for the traffic information service between VMS and smart phone navigation by conducting a survey using a stated preference in Busan Metropolitan City in August 2013. This study found that 60% of survey respondents prefer VMS to the smart phone navigation. Further analysis to investigate the preference focused on the smart phone users revealed that female, younger, more educated, and less experienced drivers more rely on the smart phone navigation. Consequently, this study implicates that private and governmental institutes have to take a measure to develop the integrated traffic information system.

Developing a Freeway Flow Management Scheme Under Ubiquitous System Environments (유비쿼터스 환경에서의 연속류 적정속도 관리 기술 개발)

  • Park, Eun-Mi;Seo, Ui-Hyeon;Go, Myeong-Seok;O, Hyeon-Seon
    • Journal of Korean Society of Transportation
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    • v.28 no.4
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    • pp.167-175
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    • 2010
  • The ubiquitous transportation system environments make it possible to collect each vehicle's position and velocity data and to perform more sophisticated traffic flow management at the individual vehicle or platoon level through vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) communication. It is necessary to develop a traffic flow management scheme to take advantage of the ubiquitous transportation system environments. This paper proposes an algorithm to advise the optimal speed for each vehicle according to the traffic flow condition. The algorithm aims to stabilize the traffic flow by advising the equilibrium speed to the vehicles speeding or crawling under freely flowing condition. And it aims to prevent or at least alleviate the shockwave propagation by advising the optimal speed that should dampen the speed drop under critical flow conditions. This paper builds a simulation testbed and performs some simulation experiments for the proposed algorithm. The proposed algorithm shows the expected results in terms of travel time reduction and congestion alleviation.