• Title, Summary, Keyword: secondary collision

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A Study on Prevention of Secondary Collision considering Failure of Brake Actuator (제동 액츄에이터 손상을 고려한 2차 충돌 예방에 관한 연구)

  • Yang, Heecheol;Kim, Dooyong;Kang, Taewan;Soh, Minwoo;Kwon, Jaejoon;Park, Kihong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.5
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    • pp.553-563
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    • 2015
  • Reportedly the fatality rate from secondary collision is six times higher than the average fatality rate from all traffic accidents. So prevention of the secondary collision is attracting significant attention from automotive industries. However, the secondary collision prevention systems that have been developed are not considering possibility of brake actuator failure that can occur by the impact during the initial collision. In this paper, a new system has been developed that could prevent secondary collision even in case of brake actuator failure by taking advantage of still operating actuators. In this system, a steering control is performed for maintaining a lane by using linear quadratic regulator. Additionally, the system attempts differential brake control with the remaining braking capability to stop the vehicle in the shortest distance. Through simulation in various collision scenarios, the system has demonstrated significant potential of preventing secondary collision that could otherwise have resulted in severe fatality.

An Improved DSA Strategy based on Triple-States Reward Function (Triple-state 보상 함수를 기반으로 한 개선된 DSA 기법)

  • Ahmed, Tasmia;Gu, Jun-Rong;Jang, Sung-Jeen;Kim, Jae-Moung
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.47 no.11
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    • pp.59-68
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    • 2010
  • In this paper, we present a new method to complete Dynamic Spectrum Access by modifying the reward function. Partially Observable Markov Decision Process (POMDP) is an eligible algorithm to predict the upcoming spectrum opportunity. In POMDP, Reward function is the last portion and very important for prediction. However, the Reward function has only two states (Busy and Idle). When collision happens in the channel, reward function indicates busy state which is responsible for the throughput decreasing of secondary user. In this paper, we focus the difference between busy and collision state. We have proposed a new algorithm for reward function that indicates an additional state of collision which brings better communication opportunity for secondary users. Secondary users properly utilize opportunities to access Primary User channels for efficient data transmission with the help of the new reward function. We have derived mathematical belief vector of the new algorithm as well. Simulation results have corroborated the superior performance of improved reward function. The new algorithm has increased the throughput for secondary user in cognitive radio network.

Collision Behaviors Analysis of Sandwich Concrete Panel for Outer Shell of LNG Tank (LNG외조를 구성하는 샌드위치 콘크리트 패널의 충돌거동해석)

  • Lee, Gye Hee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.6
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    • pp.485-493
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    • 2017
  • In this study, the collision analysis of SCP(Sandwich Concrete Panel) composing the outer tank of LNG storage was performed and its collision behavior was analyzed. For the same collision energy value proposed in BS7777 code, the collision conditions are composed by using two types of missiles and various collision speeds. Nonlinear dynamic analysis models were constructed to perform numerical analysis on the various collision conditions. Also, the collision behavior was analyzed assuming that the second collision with the same collision energy occurs at the same point after the first collision. As a result of the analysis, it was found that with smaller missile and low collision speed had caused larger deformation. The collision energy dissipated in ratio of about 6: 4 in the outer steel plate and the inner filling concrete. In the results of double collision analysis, the final collisional deformation was dominated by the size of the second missile, and the amount of deformation due to the second collision was smaller than that of the first collision because of the membrane behavior of the steel plates. In the offset double collision cases, the largest deformation occurs at the secondary collision point regardless of the offset distance.

RawPEACH: Multiband CSMA/CA-Based Cognitive Radio Networks

  • Chong, Jo-Woon;Sung, Young-Chul;Sung, Dan-Keun
    • Journal of Communications and Networks
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    • v.11 no.2
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    • pp.175-186
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    • 2009
  • A new medium access control (MAC) scheme embedding physical channels into multiband carrier sense multiple access/collision avoidance (CSMA/CA) networks is proposed to provide strict quality of service (QoS) guarantee to high priority users. In the proposed scheme, two priority classes of users, primary and secondary users, are supported. For primary users physical channels are provided to ensure strict QoS, whereas secondary users are provided with best-effort service using CSMA/CA modified for multiband operation. The performance of the proposed MAC scheme is investigated using a new multiband CSMA/CA Markov chain model capturing the primary user activity and the operation of secondary users in multiple bands. The throughput of secondary users is obtained as a function of the primary user activity and other CSMA/CA parameters. It is shown that the new MAC scheme yields larger throughput than the conventional single-band CSMA/CA when both schemes use the same bandwidth.

A study on the Crashworthiness Design of Bow Structure of Oil Carriers -Collision Behaviour of Simplified Models(1) (유조선 선수부의 내충돌 구조설계에 관한 연구 -이상화 모델의 충돌거동 분석(1))

  • 신영식;박명규
    • Journal of Ocean Engineering and Technology
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    • v.15 no.3
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    • pp.120-127
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    • 2001
  • The potential pollution problems resulting from tanker collision necessitate the requirement for an effective structural design and the development of relevant safety regulations. During a few decades, the great effort has been made by the international Maritime Organization and the Administration, etc, to reduce oil spillage from collision accidents. However there is still a need for investigation in the light of structural evaluation method for the experiments and rational analysis, and design development for an operational purpose of ships. This study aims for investigating a complicated structural response of bow structures of simplified models and oil carriers for assessing the energy dissipation and crushing mechanics of the striking vessels through a methodology of the numerical analysis for the various models and its design changes. Through these study an optimal bow construction absorbing great portion of kinetic energy at the least penetration depth prior to reach to the cargo area and an effective location of collision bulkhead are investigated. In order to obtain a rational results in this study, three stages of collision simulation procedures have been performed step by step as follows; 1) 16 simplified ship models are used to investigate the structural response against bow collision with variation of primary and secondary members. Mass and speed are also varied in four conditions. 2) 21 models consisted of 5 sizes of the full scaled oil carriers are used to perform the collision simulation with the various sizes and deadweight delivered in a recent which are complied with SOLAS and MARPOL. 3) 36 models of 100l oil carrier are used to investigate the structural response and its influence to the collision bulkhead against bow collision in variation with location of collision bulkhead, primary members, framing system and colliding conditions, etc. By the first study using simplified models the response of the bow collision is synthetically evaluated for the parameters influencing to the absorbed energy, penetration depth and impact force, etc.

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A Study on the Crashworthiness Design of Bow Structure of Oil Carriers (유조선 선수부의 내충돌 구조설계에 관한 연구)

  • 신영식;박명규
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.119-126
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    • 2001
  • The potential pollution problems resulting from tanker collision necessitate the requirement for an effective structural design and the development of relevant safety regulation. During a few decades, the great effort has been made by International Maritime Organization and the Administration, etc, to reduce oil spillage from collision accidents. However there is still a need for investigation in the light of structural evaluation method for the experiments and rational analysis, and design development for an operational purpose of ships. This study is aimed at investigating a complicated structural response of bow structures of oil carriers for assessing the energy dissipation and crushing mechanics of striking vessel through a methodology of the numerical analysts for the various models and its design changes. Through this study an optimal bow construction absorbing great portion of kinetic energy in the least penetration depth prior to reach to the cargo area and an effective location of collision bulkhead are investigated. In order to obtain a rational results in this study, three stages of response analysis procedures are performed as follows; 1). 16 simplified ship models are used to investigate the structural response against bow collision with variation of primary and secondary members. Mass and speed are also varied in two conditions. 2). 21 models conisted of 5 size of full scaled oil carriers are used to perform the collision simulation with the various sizes and deadweight delivered in a recent which are complied with SOLAS and MARPOL. 3). 36 models of 100k oil carrier are used to investigate the structural response and its influence to the collision bulkhead against bow collision in variation with location of collision bulkhead, primary mombers, framing system and colliding conditions, etc.

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Reconstruction Analysis of Vehicle-pedestrian Collision Accidents: Calculations and Uncertainties of Vehicle Speed (차량-보행자 충돌사고 재구성 해석: 차량 속도 계산과 불확실성)

  • Han, In-Hwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.5
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    • pp.82-91
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    • 2011
  • In this paper, a planar model for mechanics of a vehicle/pedestrian collision incorporating road gradient is derived to evaluate the pre-collision speed of vehicle. It takes into account a few physical variables and parameters of popular wrap and forward projection collisions, which include horizontal distance traveled between primary and secondary impacts with the vehicle, launch angle, center-of-gravity height at launch, distance from launch to rest, pedestrian-ground drag factor, the pre-collision vehicle speed and road gradient. The model including road gradient is derived analytically for reconstruction of pedestrian collision accidents, and evaluates the vehicle speed from the pedestrian throw distance. The model coefficients have physical interpretations and are determined through direct calculation. This work shows that the road gradient has a significant effect on the evaluation of the vehicle speed and must be considered in accident cases with inclined road. In additions, foreign/domestic empirical cases and multibody dynamic simulation results are used to construct a least-squares fitted model that has the same structure of the analytical one that provides an estimate of the vehicle speed based on the pedestrian throw distance and the band within which the vehicle speed would be expected to be in 95% of cases.

Performance Analysis of Collision Probability Between Primary User and Secondary Users in Spectrum Sensing Cognitive Radio Network With Synchronization Errors (동기화 에러가 존재하는 스펙트럼 감지 무선 인지 네트워크에서 일차 사용자와 이차 사용자들 간의 충돌 확률 분석)

  • Hong, Seung Geun;Im, Gyeongrae;Lee, Jae Hong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.21-23
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    • 2017
  • 본 논문에서는 스펙트럼 감지 무선 인지 네트워크에서 동기화 에러가 존재하는 환경을 고려한다. 동기화에러가 존재 할 때 주어지는 오검출 확률(miss detection probability)을 이용하여 일차 사용자와 이차 사용자들 간의 충돌 확률(collision probabliyt)를 유도한다. 유도된 수식을 몬테 카를로 모의실험(Monte Carlo simulation)을 통해 확인한다.

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Throughput Performance of Common Spreading Code and Transmitter-Oriented CDMA Packet Radio Networks (단일확산 코드 및 송신기별 코드분할 다중 접속(CDMA) 패킷 라이도 네트워크들의 Throughput 성능)

  • 김동인
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.17 no.9
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    • pp.939-950
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    • 1992
  • The performance of common spreading code scheme employing multiple-capture receiver is compared to that of transmitter-oriented (T/O) code division multiple access (CDMA) scheme in view of the possibility of collision-free transmissions and the effect of secondary multiple-access interference. For performance comparisons, secondary multiple-access interference is characterized for the common code scheme and the T/O CDMA scheme that assures perfectly collision-free transmissions. Throughput performance is then evaluated for these two schemes with direct-sequence spread-spectrum/differential-phase-shift-keying (DS-SS/DPSK) data modulation and forward-error-control coding (BCH codes) in the presence of an additive white Gaussian noise (AWGN). It is shown that when the number of radios is relatively large, the maximum normalized throughput is greater for the common code scheme than for the T/O CDMA scheme at a moderate signal-to-noise ration(SNR).

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Secondary Electron Emission Properties with Lead and Lead-Free Dielectric in AC-PDP

  • Cha, Myung-Lyoung;Lee, Hye-Jung;Choi, Eun-Ha;Kim, Hyung-Sun
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1255-1257
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    • 2005
  • The increase of secondary electron-emitting coefficient is effective to reduce the discharge voltage as well as to improve the luminance efficiency of PDP. We investigated the properties of ${\gamma}$ with composition and different dielectric constants, and the microstructure of dielectric after ion collision. As a result the dielectric of PbO system showed higher ${\gamma}$ compared with Pb-free system. However, there was no difference in ${\gamma}$ when the MgO protective layer was covered.

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