• 한국ITS학회 논문지
• /
• 제17권6호
• /
• pp.144-152
• /
• 2018

본 연구는 기존 교통정보 수집체계의 한계를 보완하기 위한 수단으로써 드론을 사용하였을 경우 교통량, 속도, 밀도 등의 정보를 단시간에 경제적으로 수집 가능하다는 점에 착안하였으며, 이를 위해 드론을 실제 교통현장 촬영영상 분석을 통해 추출된 핵심 교통정보의 타당성 검증과 더불어 다양한 정보수집시나리오 분석을 통해 최적의 교통정보 추출 방법론을 제시하고자 하였다. 본 연구 수행결과, 드론은 단시간에 경제적인 교통정보수집이 가능한 유용한 정보수집 보완수단임은 물론, 매우 간단하고 직관적인 방법으로 연속류 구간의 서비스수준 판정을 가능하게 해 주는 강점이 있는 것으로 확인되었다.

• Journal of Communications and Networks
• /
• 제6권4호
• /
• pp.317-330
• /
• 2004

In this paper, we explore the utility of recently discovered multiple-antenna techniques (namely MIMO techniques) for medium access control (MAC) design and routing in mobile ad hoc networks. Specifically, we focus on ad hoc networks where the spatial diversity technique is used to combat fading and achieve robustness in the presence of user mobility. We first examine the impact of spatial diversity on the MAC design, and devise a MIMO MAC protocol accordingly. We then develop analytical methods to characterize the corresponding saturation throughput for MIMO multi-hop networks. Building on the throughout analysis, we study the impact of MIMO MAC on routing. We characterize the optimal hop distance that minimizes the end-to-end delay in a large network. For completeness, we also study MAC design using directional antennas for the case where the channel has a strong line of sight (LOS) component. Our results show that the spatial diversity technique and the directional antenna technique can enhance the performance of mobile ad hoc networks significantly.

• 전기학회논문지
• /
• 제60권12호
• /
• pp.2386-2391
• /
• 2011

Tracking and detecting targets by the millimeter wave seeker is affected by moving of platform. In order to perform the tracking performance, stabilization of a millimeter wave seeker which consists of 2-axis gimbals was considered in this study. The feasibility of the analysis and the 2-axis gimbal servo system modeling design were verified along with some simulation results.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권2호
• /
• pp.524-539
• /
• 2014

To investigate schemes of secret key generation from Ultra-wideband (UWB) channel, we study a statistical characterization of UWB outdoor channel for a campus playground scenario based on extensive measurements. Moreover, an efficient secret key generation mechanism exploiting multipath relative delay is developed, and verification of this algorithm is conducted in UWB Line-of-sight (LOS) outdoor channels. For the first time, we compare key-mismatch probability of UWB indoor and outdoor environments. Simulation results demonstrate that the number of multipath proportionally affects key generation rate and key-mismatch probability. In comparison to the conventional method using received signal strength (RSS) as a common random source, our mechanism achieves better performance in terms of common secret bit generation. Simultaneously, security analysis indicates that the proposed scheme can still guarantee security even in the sparse outdoor physical environment free of many reflectors.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송∙미디어공학회 2019년도 추계학술대회
• /
• pp.5-6
• /
• 2019

최근 보행자 행태를 반영한 미시적 시뮬레이션 분석이 가능하게 되었다. 차량 분석과 유사하게 보행자 행태 중 가장 빈번히 사용되는 것은 보행속도로 이는 횡단보도 보행자 녹색시간 산정과도 매우 밀접한 관계가 있다. 또한 보도의 밀도를 산정함에 있어서 보행자 속도는 중요한 역할을 담당한다. 이에 본 논문에서는 횡단보도의 보행자 속도를 실측하고, 이를 기반으로 미시적 시뮬레이션인 VISSIM의 주요 파라메타인 보행속도를 이용하여 역삼역 일대의 보행실태를 점검해 보았다. 분석에 사용된 보행속도 실측자료는 서울시 16개 횡단보도에서 조사되었으며, 연령별로 일반인(64세 이하)과 노인(65세 이상)을 구분하여 분석하였다.

• The Korean Journal of Ceramics
• /
• 제2권4호
• /
• pp.231-237
• /
• 1996

Mullite ceramics can be sintered by rf plasma sintering to densities as high as 97% compared to the theoretical density of the mullite, while SiC whisker-reinforced mullite matrix ceramic composites were not sintered by plasma sintering. Decomposition of mullite occurs in a superficial regins at the outside surface of the specimen by volatilization of SiO at elevated temperature by plasma. SiC whiskers were destroyed, and the matrix was converted to alumina from SiC-whisker reinforced mullite matrix ceramic composites during the plasma sintering. Accelerated volatilization from the SiC whisker in the mullite prevents sintering. The volatile species are mainly SiC and CO gas species. The effects of plasma on mullite and SiC-whisker reinforced mullite matrix composites are interpreted by thermodynamic simulation of the volatile species in the plasma environment. The thermodynamic results show that the decomposition will not occur during hot pressing.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(II)
• /
• pp.297-304
• /
• 2003

As the high speed rail to be opened at 2004, the. railroad will dominate over the transportation market in the Seoul-Busan corridor compared to road transport. But, it is obvious that the LOS(level of service) of railroad at 2004 will be worse in the areas that are not served KTX. For the speed-up of conventional line, it is a worldwide trend that tilting trains are served on the conventional railway line. That is the reason serving tilting trains is very efficient to use existing facilities and improve cruise time when capacity is available. In this paper, we suggest 10 routes are replaced with present operating trains(saemaeul, mugunghwa) by the tilting train.

• 제어로봇시스템학회논문지
• /
• 제17권9호
• /
• pp.947-953
• /
• 2011

Radome aberration error causes degradation of miss distance as well as stability of high maneuver missile system with RF seeker. A study about radome compensation method is important in this kind of missile system design. Several kinds of methods showed good compensation performance in their paper. Proposed adaptive Particle filter estimates line of sight rate excluding the radome induced error. This paper shows effectiveness of adaptive Particle filter as compensation method of radome aberration error. Robust performance of this filter depends on external aiding measurement, target acceleration. Tuning of system error covariance can make this filter unsensitive against the error of target acceleration information. This paper demonstrates practical usage of adaptive Particle filter for reducing miss distance and increasing stability against disturbance of radome aberration error through performance analysis.

• Interaction and multiscale mechanics
• /
• 제2권4호
• /
• pp.333-352
• /
• 2009

We introduce a radial basis collocation method to solve axially moving beam problems which involve $2^{nd}$ order differentiation in time and $4^{th}$ order differentiation in space. The discrete equation is constructed based on the strong form of the governing equation. The employment of multiquadrics radial basis function allows approximation of higher order derivatives in the strong form. Unlike the other approximation functions used in the meshfree methods, such as the moving least-squares approximation, $4^{th}$ order derivative of multiquadrics radial basis function is straightforward. We also show that the standard weighted boundary collocation approach for imposition of boundary conditions in static problems yields significant errors in the transient problems. This inaccuracy in dynamic problems can be corrected by a statically condensed semi-discrete equation resulting from an exact imposition of boundary conditions. The effectiveness of this approach is examined in the numerical examples.

• Nuclear Engineering and Technology
• /
• 제45권6호
• /
• pp.803-810
• /
• 2013

The U.S. Department of Energy's Fuel Cycle Technologies R&D program under the Office of Nuclear Energy is working to advance technologies to enhance both the existing and future fuel cycles. One thrust area is in developing enabling technologies for next generation nuclear materials management under the Materials Protection, Accounting and Control Technologies (MPACT) Campaign where advanced instrumentation, analysis and assessment methods, and security approaches are being developed under a framework of Safeguards and Security by Design. An overview of the MPACT campaign's activities and recent accomplishments is presented along with future plans.