• Title/Summary/Keyword: 충돌 성능

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Tone-Based Access Scheme with Repetitive Contention in Contention-Based Medium Access Control (경쟁 기반 MAC에서의 반복적 톤 기반 경쟁 기법)

  • Ahn, Jae-Hyun;Yun, Jeong-Kyun;Bahk, Sae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.5A
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    • pp.460-466
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    • 2007
  • There are two coordination functions in IEEE 802.11 standard. One is PCF, polling based function, and the other is DCF, contention based function. DCF is simpler than PCF but the performance is similar with the latter. That's the reason why DCF is more popular than PCF. However, DCF has a risk of collision with other nodes in the network because the function is a distributed contention based one. CSMA/CA of DCF has collision avoidance algorithm in it, but the performance of avoidance algorithm has limitations. In this paper we proposed a new scheme called TAR(Tone-based Access scheme with Repetitive conention). In TAR, there is narrow contention-only channel other than original data transmitting channel, so that both a data transmission and the contention can be performed simultaneously. The TAR uses the same contention concept with the CSMA/CA, but it has the originality for the narrow contention channel and the repetitive contention scheme which greatly reduce the collision probability. We proved the performance of TAR by some simulations, and it showed good results.

A Study on Crash Analysis of Vehicle and Guardrail using a LS-DYNA Program (LS-DYNA 프로그램을 이용한 차량과 가드레일의 충돌해석에 관한 연구)

  • Kwon, O-Hyun;Baek, Se-Ryong;Yoon, Jun-Kyu;Lim, Jong-Han
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.3
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    • pp.179-186
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    • 2016
  • A study is to research crash barriers for vehicles that prevent road breakaway of vehicles and protect car passengers and pedestrians as absorbing impulse. Protection performance tests on vehicle passengers were simulated by using a LS-DYNA program. Through repetitive simulation on various speed and angles, passenger protection performance according to different impact condition was contemplated. Variable setting for the simulation was calculated as the mean weight of domestic car sales. By analyzing NASS (National Automotive Sampling System) of NHTSA (National Highway Traffic Safety Administration) of the U.S., the actual speed and collision angle section of accidents were computed. As a result, we confirmed that THIV (Theoretical Head Impact Velocity) and PHD (Post-impact Head Deceleration) are increased according to the impact speed and angle. Also, when the vehicle hit the guardrail post, we could be confirmed that the passenger protection performance greatly decreased.

Analysis of impact damage behavior of GFRP-strengthened RC wall structures subjected to multiple explosive loadings (복합 폭발하중을 받는 GFRP 보강 RC 벽체 구조물의 비선형 충격 손상거동 해석)

  • Noh, Myung-Hyun;Lee, Sang-Youl;Park, Tae-Hyo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.1033-1036
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    • 2008
  • In this paper, the analysis of impact damage behavior of a reinforced concrete structure that undergoes both a shock impulsive loading and an impact loading due to the air blast induced from an explosion is performed. Firstly, a pair of multiple loadings are selected from the scenario that an imaginary explosion accident is assumed. The RC structures strengthened with glass fiber reinforced polymer (GFRP) composites are considered as a scheme for retrofitting RC wall structures subjected to multiple explosive loadings and then the evaluation of the resistant performance against them is presented in comparison with the result of the evaluation of a RC structure without a retrofit. Also, in order to derive the result of the analysis similar to that of real explosion experiments, which require the vast investment and expense for facilities, the constitutive equation and the equation of state (EOS) which can describe the real impact and shock phenomena accurately are included with them. In addition, the numerical simulations of two concrete structures are achieved using AUTODYN-3D, an explicit analysis program, in order to prove the retrofit performance of a GFRP-strengthened RC wall structure.

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High-Tag anti-collision algorithm to improve the efficiency of tag Identification in Active RFID System (능동형 RFID시스템에서 태그 인식 속도 향상을 위한 고속 태그 충돌 방지 알고리즘)

  • Lee, Han-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.2
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    • pp.235-242
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    • 2012
  • In RFID System, one of the problem that we must slove is to devise a good anti-collision algorithms to improve the efficiency of tag identification which is usually low because of tag collision. Among of the existing RFID anti-collision algorithm, BS (Binary Search) algorithm, though simple, has a disadvantage that the stage of times used to identify the tags increase exponentially as the number of tags does. In this paper, I propose a new anti-collision algorithm called Multi-collision reflected frame which restricts the number of stages and decided bit. Since the proposal algorithm keep the length size of UID and density of total tag when have 100%. The simulation results showed that the proposed algorithm improves the efficiency by 30~50% compared to the existing algorithm.

Recursive Probabilistic Approach to Collision Risk Assessment for Pedestrians' Safety (재귀적 확률 갱신 방법을 이용한 보행자 충돌 위험 판단 방법)

  • Park, Seong-Keun;Kim, Beom-Seong;Kim, Eun-Tai;Lee, Hee-Jin;Kang, Hyung-Jin
    • Journal of the Korean Institute of Intelligent Systems
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    • v.21 no.4
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    • pp.475-480
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    • 2011
  • In this paper, we propose a collision risk assesment system. First, using Kalman Filter, we estimate the information of pedestrian, and second, we compute the collision probability using Monte Carlo Simulations(MCS) and neural network(NN). And we update the collision risk using time history which is called belief. Belief update consider not only output of Kalman Filter of only current time step but also output of Kalman Filter up to the first time step to current time step. The computer simulations will be shown the validity of our proposed method.

Spray Characteristics of Impinging Injectors in Crossflows (횡방향 유동에서 충돌형 분사기의 액체제트 분무 특성)

  • Song, Yoonho;Lee, Woongu;Ahn, Kyubok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.949-952
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    • 2017
  • Spray characteristics of the impinging injectors in subsonic crossflows were experimentally studied and compared with the plain-orifice injectors. By changing the impingement angle (60, 90, 120) which is the same orifice length to diameter ratio (L/d = 5), spray characteristics were investigated. In the view of the top view from the impinging injectors, as the impingement angle increases, the liquid column breakup length in the y-direction was decreased. On the other hand, when the impinging injector is viewed from the side view, the breakup length in the x direction is smaller than the previous plain-orifice injectors, which mean that the atomizing performance of the impingement-type injector is better than that of the single-hole orifice.

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A Study on the Performance of Mechanical Crash Sensors (기계식 충돌 센서의 성능 해석)

  • Kim, K.H.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.1
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    • pp.136-142
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    • 1995
  • An analysis model is proposed for the performance prediction of typical ball and tube type mechanical crash sensors based upon mass-spring-viscous gas damping idealization. Also a construction of mechanical crash pulse generator is suggested as an experimental tool for calibration and verification of model predictions. A sensor tuning procedure for a particular set of crash pulses is suggested based upon the analysis model and the experimental tools.

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RFID 리더의 다중접속 프로토콜

  • An, Dong-Heon;Yang, Hun-Gi;Yang, Seong-Hyeon;Kim, Yeong-Su
    • Information and Communications Magazine
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    • v.24 no.5
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    • pp.124-134
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    • 2007
  • 본 논문에서는 RFID 리더충돌 회피를 위해 제시된 다양한 RFID 리더 프로토콜을 소개한다. 이를 위한 배경지식으로 RFID 네트워크에서의 리더 충돌 환경, 리더의 채널 엑세스 과정 및 리더 간섭분석 툴에 대해 기술한다. 각각의 리더충돌 회피 방식에 대해서 알고리즘 적용가능 범위, 장단점 뿐 아니라 구체적인 프로토콜 및 시뮬레이션을 통해서 각 방식의 상대적인 성능차이를 비교한다.

Efficient Collision Detection Algorithm in Dynamic 3D Environment at Run-time (실시간 동적 3차원 환경에서의 효율적인 충돌탐지 알고리즘)

  • 이영호;김성범;정승원;한대만;한상진;구용완
    • Proceedings of the Korean Information Science Society Conference
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    • 2002.10d
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    • pp.421-423
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    • 2002
  • 본 논문에서는 실시간에 강체 운동을 하는 일반적인 모델사이의 효율적인 충돌검사 알고리즘을 제안한다. 기존의 경계볼륨 알고리즘에 계층적 구조를 적용하였다. 이는 볼록한 물체를 위한 보로노이 영역 기반의 충돌검사 알고리즘을 오목한 물체에도 적용할 수 있도록 확장한다. 추가적으로 빠르게 움직이는 물체에 대한 관통을 탐지하기 위해서 물체의 이동 경로에 대한 교차 검사를 진행한다. 구현된 알고리즘은 일반적인 응용에서 기대한 성능 향상을 얻을 수 있다.

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항해하는 선박과 부유하는 컨테이너의 충돌 가능성에 관한 연구

  • Gong, Gil-Yeong;Lee, Sang-Gap;Jeong, Chang-Hyeon;Lee, Chun-Gi
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2011.06a
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    • pp.4-6
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    • 2011
  • 부유물 부근을 항해하는 선박의 조종 운동에 미치는 부유물의 영향을 파악하기 위하여 선박과 부유물(40피트 콘테이너)을 형상화 하고 선박과 부유물간의 간섭영향을 수치 계산하였다. 이 논문에서 사용되어진 계산 방법은 충돌 회피를 위한 선박의 자동제어시스템과 해상교통제어시스템 및 항만 건설 등을 위한 초기 설계 단계에서 선박 조종성의 예측에 유용할 것이다.

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