• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권6호
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• pp.253-256
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• 2013

VANET에서는 차량 안전 관련 정보가 차량들 간에 안정적으로 전달될 수 있도록 해주는 라우팅 프로토콜이 요구된다. 본 논문에서는 도시기반의 VANET 환경에서 차량 간의 빠르고 안정적인 통신을 위하여 차량 밀도 정보를 이용한 라우팅 기법을 제안한다. 제안 기법에서 각 차량은 비콘 메시지와 도로 정보을 이용해서 도로의 차량 밀도를 계산한다. 차량들은 이 정보를 이용해서 패킷을 전송할 안정적인 경로를 설정한다. NS-2 시뮬레이션을 통해 제안 기법과 GPSR의 성능을 비교했으며, 그 결과 제안 기법이 패킷 전송 성공률 측면에서 우수한 성능을 보임을 알 수 있었다.

• 대한전자공학회논문지TC
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• 제49권4호
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• pp.53-58
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• 2012

지능형 교통시스템에서는 노변장치와 차량의 통신장치간 정보교환을 통해 차량의 정보를 수집한다. 그리고 한 노변장치의 통신범위 내의 차량밀도는 시간에 따라 바뀐다. 차량밀도가 높아지면 한 노변장치에서 수집되는 차량정보가 많아지고 패킷의 충돌 확률이 높아진다. 본 논문에서는 차량밀도에 따라 전송속도 및 전송주기를 변경하여 패킷 수신율을 높이는 IEEE 802.11p 기반 적응 전송 알고리듬을 제안한다. 차량 간 통신 프로토콜 표준인 IEEE 802.11p MAC프로토콜을 ns-2.33으로 구한하여 차량밀도의 변화에 따른 성능을 평가하였다.

• Corrosion Science and Technology
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• 제21권5호
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• pp.348-359
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• 2022

Interest in electric vehicle is on the rise due to global eco-friendly policies. To improve the efficiency of electric vehicles, it is essential to reduce weights of components. Since electric vehicles have various electronic equipment, the research on stray current corrosion is required. In this research, a galvanostatic corrosion experiment was performed on 6061-T6 Al alloy for electric vehicle battery housing using chloride concentration and applied current density as variables in a solution simulating an acid rain environment. As a result of the experiment, when chloride concentration and applied current density were increased, corrosion damage became larger. In particular, pitting damage was dominant at an applied current density of 0.1 mA/cm². Pitting damage over the entire surface was found at a current density of 1.0 mA/cm². In conclusion, chloride concentration had a relatively large effect on localized corrosion. The applied current density had a great effect on uniform corrosion. However, in the case of applied current density, localized corrosion was also greatly affected by interaction with chloride.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권5호
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• pp.874-887
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• 2011

Compared to nomadic and fixed relay stations, vehicle-mounted mobile relay stations show different characteristics caused by the time-variant topology, due to their mobility. Especially, a relay mounted in a vehicle is differentiated from nomadic or fixed relay by the restricted distance between the relay and associated mobile station and the variable density of relay deployment in a cell. In this paper, we identify the characteristics of vehicle-mounted mobile relay stations and provide some parameters that highly influence the performance of vehicle-mounted relay. Through simulation, we measure the effect of relay density, zone ratio, relay transmission power, and frame transmission mode on the performance of vehicle-mounted relay. The results show that the performance of vehicle-mounted relay is highly susceptible to the above vehicle-mounted relay-specific parameters.

• Structural Engineering and Mechanics
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• 제57권1호
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• pp.21-43
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• 2016

A conditional probability based approach known as Particle Filter Method (PFM) is a powerful tool for system parameter identification. In this paper, PFM has been applied to identify the vehicle parameters based on response statistics of the bridge. The flexibility of vehicle model has been considered in the formulation of bridge-vehicle interaction dynamics. The random unevenness of bridge has been idealized as non homogeneous random process in space. The simulated response has been contaminated with artificial noise to reflect the field condition. The performance of the identification system has been examined for various measurement location, vehicle velocity, bridge surface roughness factor, noise level and assumption of prior probability density. Identified vehicle parameters are found reasonably accurate and reconstructed interactive force time history with identified parameters closely matches with the simulated results. The study also reveals that crude assumption of prior probability density function does not end up with an incorrect estimate of parameters except requiring longer time for the iterative process to converge.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.448-461
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• 2019

Changes in gravity and buoyancy of a Full Ocean Depth Autonomous Underwater Vehicle (FOD-AUV) during its descending and ascending process must be considered very carefully compared with a Human Occupied Vehicle (HOV) or a Remotely Pperated Vehicle (ROV) whose activities rely on human decision. We firstly designed a two-step weight dropping pattern to achieve a high descending and ascending efficiency and a gravity-buoyancy balance at designed depth. The static equations showed that gravity acceleration, seawater density and displacement are three key aspects affecting the balance. Secondly, we try our best to analysis the gravity and buoyancy changing according to the previous known scientific information, such as anomaly of gravity acceleration, changing of seawater states. Finally, we drew conclusion that gravity changes little (no more than 0.1kgf, it is impossible to give a accurate value). A density-depth relationship at the Challenger Deep was acquired and the displacement changing of the FOD-AUV was calculated preciously.

• 한국산학기술학회논문지
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• 제14권2호
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• pp.561-566
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• 2013

본 연구는 유압식 자동차고 조절장치 개발 및 상기장치를 일반 상용차에 적용시키기 위한 것이다. 운전자의 승차감에 영향을 줄 진동특성을 주행시험을 통하여 파악하고자 하였다. 유압식 자동차고 조절장치는 현재 승용차에 가장 많이 사용되고 있는 맥퍼슨 형식의 형태로 설계되었다. 맥퍼슨 형식의 순정현가장치, 튜닝현가장치, 유압식 자동차고 조절장치를 장착한 차량으로 시험을 수행하였다. 자동차에 전달되는 진동특성은 랜덤형태이므로 PSD(Power Spectrum Density)값을 비교하였다.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.136-145
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• 1997

To analyzed ride quality and to predict durability in vehicle dynamics, it is essential to describe a road surface profile precisely. This paper presents a technique to generate road surface profiles in a spatial domain by using a power spectral density function. A single track power spectral density function is proposed to describe a road surface profile, which is also applicable for multi-track vehicle response analysis, The derived road surfaces are compared to ISO(International Organization for Standardization) standards and classifications, proposed by the MIRA(Motor Industry Research Association). The methodology in this paper is also proposed to generate road roughness description with a limited external data. A small amount of external curve data is combined with an internal PSD function to generate road surface roughness in a spatial domain.

• 대한조선학회지
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• 제25권2호
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• pp.1-10
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• 1988

An axially marching numerical method is developed for the simulation of the internal waves produced by translation of a submersed vehicle in a density-stratified ocean. The method provides for the direct solution of the primitive variables [$\upsilon,\;p,\;\rho$] for the nonlinear and steady state three-dimensional Euler's equation with a non-constant density term in the vehicle-fixed cartesian co-ordinate system. By utilizing a known potential flow around the vehicle for an estimate of the axial velocity gradient, the present parabolic algorithm local upstreamwise disturbances and axial velocity variation.

• 한국ITS학회 논문지
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• 제19권6호
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• pp.208-221
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• 2020

본 연구는 첨단운전자보조시스템(Advanced Driver Assistance System, ADAS)이 빠르게 보급됨에 따라 표본 프로브 차량에 설치된 ADAS로부터 얻은 개별차량의 궤적 데이터와 전방차량과의 차두거리 데이터를 이용하여 연속류의 교통밀도를 추정 및 분석하는 것을 목적으로 한다. 과거 연속류 교통밀도는 주로 차량검지시스템(Vehicle Detection System, VDS)에서 수집되는 교통량, 속도, 점유율 등의 데이터를 가공하여 추정되거나, CCTV등의 영상정보를 활용하여 직접 차량 대수를 계수하여 추정되었다. 이러한 방식은 교통밀도 추정의 공간적 제약이 있고, 교통 혼잡시 추정의 신뢰도가 낮다는 한계를 보였다. 이에 본 연구에서는 선행연구의 한계를 극복하기 위해 ADAS로부터 수집된 개별차량 궤적 데이터와 차두거리 정보를 활용하여 도로의 공간을 검지하고 일반화된 밀도(Generalized Density)방식을 이용하여 시공간적 교통밀도를 추정한다. 이에 따라 ADAS차량의 표본율에 따른 교통밀도 추정의 정확도를 분석한 결과, 30%의 표본율일 경우 교통밀도 참 값과 약 90% 일치하는 것으로 나타났다. 이를 통해 본 연구는 향후 ADAS 및 자율주행차량이 혼재되는 도로 상황에서 신뢰도 높은 교통밀도 추정을 가능하게 하며 효율적인 교통운영관리에 기여할 수 있을 것으로 판단된다.