• Journal of Platform Technology
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• v.9 no.3
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• pp.44-51
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• 2021

In general, golden time refers to the most important time in the initial response to accidents such as saving lives or extinguishing fires. The golden time varies from disaster to disaster, but is aimed at five minutes in terms of fire and first aid. However, for the actual site, the average dispatch time for ambulances is 9 minutes and the average transfer time is 17.6 minutes, which is quite large compared to the golden time. There are various causes for this delay, but the main cause is traffic jams. In order to solve the problem, the government has established emergency car concession obligations and secured golden time to prioritize ambulances in places with the highest accident rate, but it is not a solution in rush hour when traffic is increasing rapidly. Therefore, this paper proposed a deep learning-based emergency vehicle priority signal system using collected sound data by installing sound sensors on traffic lights and conducted an experiment to classify frequency signals that differ depending on the distance of the emergency vehicle.

• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.63-72
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• 2008

Signalized intersections are operated without a signal preemption control strategy in Korea, thus there is no priority treatment for an emergency vehicle passing through the intersections. In this paper, a signal preemption control strategy is introduced to improve the safety and operational efficiency of an emergency vehicle. Using the micro simulation tool, the effects on delay and travel speed of the signal preemption control strategy are analyzed for various traffic conditions to identify the general performance trends. Then, another simulation analysis is performed to verify the feasibility of the control strategy using real network data collected from field study. Results show that the preemption control strategy provides the positive impact on emergency vehicles' operation, but the positive impact is reduced as the v/c ratios increase. As expected, the average delays of the normal vehicles are slightly increased, but the magnitude is not significant. Therefore, it is expected that the introduction of the preemption control strategy in Korea would produce the positive social benefits.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1492-1512
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• 2011

Due to multiple hops, mobility and time-varying channel, supporting delay sensitive real-time traffic in wireless local area network-based (WLAN) mesh networks is a challenging task. In particular for real-time traffic subject to medium access control (MAC) layer control overhead, such as preamble, carrier sense waiting time and the random backoff period, the performance of real-time flows will be degraded greatly. In order to support real-time traffic, an efficient adaptive packet scheduling (APS) scheme is proposed, which aims to improve the system performance by guaranteeing inter-class, intra-class service differentiation and adaptively adjusting the packet length. APS classifies incoming packets by the IEEE 802.11e access class and then queued into a suitable buffer queue. APS employs strict priority service discipline for resource allocation among different service classes to achieve inter-class fairness. By estimating the received signal to interference plus noise ratio (SINR) per bit and current link condition, APS is able to calculate the optimized packet length with bi-dimensional markov MAC model to improve system performance. To achieve the fairness of intra-class, APS also takes maximum tolerable packet delay, transmission requests, and average allocation transmission into consideration to allocate transmission opportunity to the corresponding traffic. Detailed simulation results and comparison with IEEE 802.11e enhanced distributed channel access (EDCA) scheme show that the proposed APS scheme is able to effectively provide inter-class and intra-class differentiate services and improve QoS for real-time traffic in terms of throughput, end-to-end delay, packet loss rate and fairness.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.15-22
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• 2012

A performance index of singalized intersections is a standard to optimize signal control variables and to manage traffic flow. Traffic delays is generally used to minimize the average delay time on intersections or networks, progression efficiency is used to improve travel speed of main cooridors or to provide transit signal priority. We manage traffic flows with only selecting one index between delays and progression according to the objective of traffic management and field characteristics. In real field, the driver's satisfaction is high in any performance criteria when the waiting time is shorter and the unnecessary stop in front of traffic is smaller. This paper aims to develop simulation model to represent real progression with concurrently considering delays and progression. In order to reflect an effect of level of traffic volumes and residual queues which don't be considered in prior progression model, we apply shockwave model with flow-density diagram. We derive Cell Transmission Model of Daganzo in order to develop the delay index and the progression index for the macroscopic simulation model. In order to validate the effect, we analysis traffic delays and progression efficiency with comparing this model to Transyt-7F and PASSER V.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.5
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• pp.1049-1068
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• 2011

In this paper a simple and effective call admission control (CAC) scheme is proposed for the emerging interleave-division multiple-access (IDMA) systems, supporting a variety of traffic types and offering different quality of service (QoS) requirements and priority levels. The proposed scheme is signal-to-interference-plus-noise ratio (SINR) evolution based CAC (SE-CAC). The key idea behind the scheme is to take advantage of the SINR evolution technique in the process of making admission decisions, which is developed from the effective chip-by-chip (CBC) multi-user detection (MUD) process in IDMA systems. By virtue of this semi-analytical technique, the MUD efficiency can be estimated accurately. Additionally, the computational complexity can be considerably reduced. These features make the scheme highly suitable for IDMA systems, which can combat intra-cell interference efficiently with simple CBC MUD. Analysis and simulation results show that compared to the traditional CAC scheme considering MUD efficiency as a constant, the proposed SE-CAC scheme can guarantee high power efficiency and throughput for multimedia traffic even in heavy load conditions, illustrating the high efficiency of CBC MUD. Furthermore, based on the SINR evolution, the SE-CAC can make accurate estimation of available resource considering the effect of MUD, leading to low outage probability as well as low blocking and dropping probability.

• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.115-123
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• 2002

This thesis proposes a new type of Input-Output Buffered ATM Switch which employs an arbiter and its performance under different traffic conditions studied. The proposed switch is designed with a view to exploit the architecture and other characteristics of the arbiter. The primary aim of the proposed switch is the elimination, or at least, the reduction of HOL blocking phenomenon which occurs in the simple input buffered switch. Several HOL arbitration algorithms have been proposed for this purpose in the literature. The proposed switch attempts to reduce the HOL blocking as it uses the arbiter and the buffer at the output port in an effective manner. The arbiter is designed to work with Three Phase Algorithm which is one of the many well known HOL arbitration algorithms. The Proposed switch acquires control over priority transmission through the REQ signal. As the signals are transmitted to the arbiter, the latter controls the one which is sent by the input buffer. Computer simulation results have been provided to demonstrate the effectiveness of the Proposed switch under uniform traffic conditions.

• Journal of the Korea Society of Computer and Information
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• v.8 no.2
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• pp.97-105
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• 2003

This thesis proposes a new type of Input-Output Buffered ATM Switch which employs an arbiter and its performance under different traffic conditions studied. The proposed switch is designed with a view to exploit the architecture and other characteristics of the arbiter The primary aim of the proposed switch is the elimination, or at least, the reduction of HOL blocking phenomenon which occurs in the simple input buffered switch. Several HOL arbitration algorithms have been proposed for this purpose in the literature. The Proposed switch attempts to reduce the HOL blocking as it uses the arbiter and the buffer at the output Port in an effective manner. The arbiter is designed to work with Three Phase Algorithm which is one of the many well known HOL arbitration algorithms . The proposed switch acquires control over priority transmission through the REd signal. As the signals are transmitted to the arbiter, the latter controls the one which is sent by the input buffer. Computer simulation results have been provided to demonstrate the effectiveness of the proposed switch under non-uniform random traffic conditions.