• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.4
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• pp.345-351
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• 2013

The IWRAP program (Inland Waterway Risk Assessment Program) is a useful program for risk assessment of a waterway. However, in the basic version, the function which is used to import AIS data is not included. So users have to prepare the data and input to the program manually. And not all waterways have enough statistical data about passing vessels especially in developing countries as Vietnam. This paper studies the development of a program to pre-process AIS data for using the IWRAP Mk2 program basic version. In addition, it provides users basic information about marine traffic in a waterway such as routes layout, number of passages at a gate classified by type, size and time. The developed program, named TOAIS (Total AIS), was successfully used to pre-process AIS data collected in the Vung Tau waterway-Vietnam. As a result, the IWRAP Mk2 program basic version using data pre-processed from TOAIS could effectively assess the risk of collision in this waterway.

• Science of Emotion and Sensibility
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• v.23 no.2
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• pp.103-120
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• 2020

Using driving simulation, this study investigated the effects of driver's trust in the adaptive cruise control (ACC) system and road density on driver's workload and situation awareness. The drivers were allocated into one of four experimental conditions manipulated by ACC system trust level (trust-increased vs. trust-decreased) and road congestion (high vs. low). The workload and situational awareness of the participants were measured as dependent variables. The results showed followings. First, trust-decreased group for the ACC system had significantly lower trust scores for the system in all of the measurement items, including reducing the driving load and securing safe driving due to the use of this system, than the trust-increased group. Second, the trust-decreased group showed a slower reaction time in the secondary tasks and higher subjective workload than trust-increased group. Third, in contrast, the situational awareness for the driving situation was significantly higher in the trust-decreased group than trust-increased group. The results of this study showed that the driver's trust in the ACC system can affect the various information processing performed while driving. Also, these results suggest that trust in the user's system should be considered as an important variable in the design of an automated driving assistance system.

• The KIPS Transactions:PartC
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• v.14C no.2
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• pp.139-146
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• 2007

Mobile Sensor Network(MSN) is actively studied due to the advent of mobile sensors such as Robomote and Robotic Sensor Agents(RSAs), However, existing studies on MSN have mainly focused on coverage hole problem which occurs in Stationary Sensor Network(SSN). To address coverage hole problem, these studies make mobile sensors move temporarily so that they do not make the best use of the mobility of mobile sensors, Thus, a mechanism utilizing the continuous movement of mobile sensors is proposed to improve the network coverage performance. However, this mechanism is presently immature and does not explain how to make routing path and send data from mobile sensors to a sink node, Therefore, to efficiently make routing path and send data from mobile sensors to a sink node, we propose a communication protocol for mobile sensor network where mobile sensors continuously move. The proposed protocol deploys not only mobile sensors but also stationary sensors which send sensing data to a sink node instead of mobile sensors. Simulation results show that the proposed protocol improves the performance in terms of network coverage and traffic overhead, compared to conventional SSN protocols.

• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.169-180
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• 2009

With fixed sinks, the network stability could be improved while the network life time could be decreased by the rapid energy dissipation around the fixed sink because of the concentrated network traffic from sensor nodes to the fixed sink in wireless sensor network. To address this problem, mobile sinks, which decentralize the network traffic, has received a lot of attention from many researchers recently. Since a mobile sink has a limited period to communicate with each sensor nodes, it is necessary for a scheduling algorithm to provide the fairness of data collection from each sensor nodes. In the paper, we propose the new scheduling algorithm, ASF(Availability based Scheduling scheme for Fair data collection), for the fair data collection by a mobile in the sensor networks. The ASF takes account of the distance between each sensor nodes and the mobile sink as scheduling metric, as well as the amount of collected data from each sensor nodes. Experiment results shows that the ASF improves the fairness of data collection among the sensor nodes, comparing to existing algorithm.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.385-398
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• 2002

To accommodate the increasing number of mobile terminals in the limited radio spectrum, wireless systems have been designed as micro/picocellular architectures for a higher capacity. This reduced coverage area of a cell has caused a higher rate of hand-off events, and the hand-off technology for efficient process becomes a necessity to provide a stable service. Population-based Bandwidth Reservation(PBR) Scheme is proposed to provide prioritized handling for hand-off calls by dynamically adjusting the amount of reserved bandwidth of a cell according to the amount of cellular traffic in its neighboring cells. We analyze the performance of the PBR scheme according to the changes of a fractional parameter, f, which is the ratio of request reservation to the total amount of bandwidth units required for hand-off calls that will occur for the next period. The vague of this parameter, f should be determined based on QoS(Quality of Service) requirement. To meet the requirement the value of Parameter(f) must be able to be adjusted dynamically according to the changing traffic conditions. The best value of f can be determined by a function of the average speed of mobile stations, average call duration, cell size, and so on. This paper considers the average call duration and the cell size according to the speed of mobile stations. Although some difference exists as per speed, in the range of 0.4 $\leq$ f $\leq$ 0.6, Blocking Probability, Dropping Probability and Utilization show the best values.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.8
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• pp.33-44
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• 2011

In this paper, we presents a hybrid on-chip bus architecture based on the AMBA 3.0 AXI protocol for MPSoC with high performance and low power. Among AXI channels, data channels with a lot of traffic are designed by crossbar-switch architecture for massively parallel processing. On the other hand, addressing and write-response channels having a few of traffic is handled by shared-bus architecture due to the overheads of (areas, interconnection wires and power consumption) reduction. In experiments, the comparisons are carried out in terms of time, space and power domains for the verification of proposed hybrid on-chip bus architecture. For $16{\times}16$ bus configuration, the hybrid on-chip bus architecture has almost similar performance in time domain with respect to crossbar on-chip bus architecture, as the masters's latency is differenced about 9% and the total execution time is only about 4%. Furthermore, the hybrid on-chip bus architecture is very effective on the overhead reduction, such as it reduced about 47% of areas, and about 52% of interconnection wires, as well as about 66% of dynamic power consumption. Thus, the presented hybrid on-chip bus architecture is shown to be very effective for the MPSoC interconnection design aiming at high performance and low power.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.489-496
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• 2002

This study proposes a new polling algorithm allowing dynamic change in polling period based on line utilization prediction. Polling is the most important function in network monitoring, but excessive polling data causes rather serious congestion conditions of network when network is In congestion. Therefore, existing multiple polling algorithms decided network congestion or load of agent with previously performed polling Round Trip Time or line utilization, chanced polling period, and controlled polling traffic. But, this algorithm is to change the polling period based on the previous polling and does not reflect network conditions in the current time to be polled. A algorithm proposed in this study is to predict whether polling traffic exceeds threshold of line utilization on polling path based on the past data and to change the polling period with the prediction. In this study, utilization of each line configuring network was predicted with AR model and violation of threshold was presented in probability. In addition, suitability was evaluated by applying the proposed dynamic polling algorithm based on line utilization prediction to the actual network, reasonable level of threshold for line utilization and the violation probability of threshold were decided by experiment. Performance of this algorithm was maximized with these processes.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.531-542
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• 2002

An input and output buffering ATM switch conventionally operates in either Queueloss mode or Backpressure mode. Recently, a new mode, which is called Hybrid mode, was proposed to overcome the drawbacks of Queueloss mode and Backpressure mode. In Hybrid mode, when both the destined output buffer and the originfted input buffer are full, a cell is dropped. This thesis analyzes the cell loss rate and the cell delay of Queueloss, Backpressure and Hybrid modes in a switch adopting output-port expansion scheme under uniform traffic. Output-port expansion scheme allows only one cell from an input buffer to be switched during one time slot. If several cells switch to a same destined output port, the number of maximum transfer cells is restricted to K (Output-port expansion ratio). The simulation results show that if an offered load is less than 0.9, Hybrid mode has lower cell loss rate than the other modes; otherwise, Queueloss mode illustrates the lowest cell loss rate, which is a different result from previous researches. However, the difference between Hybrid and Queueloss modes is comparably small. As expected, the average cell delay in Backpressure mode is lower than those of Queueloss mode and Hybrid mode, since the cell delay due to the retransmission of higher number of dropped cells in Backpressure mode is not considered.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.319-326
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• 2004

To help network intrusion detection systems(NIDSs) keep up with the demands of today's networks, that we the increasing network throughput and amount of attacks, a radical new approach in hardware and software system architecture is required. In this paper, we propose a Network Processor(NP) based In-Line mode NIDS that supports the packet payload inspection detecting the malicious behaviors, as well as the packet filtering and the traffic metering. In particular, we separate the filtering and metering functions from the deep packet inspection function using two-level searching scheme, thus the complicated and time-consuming operation of the deep packet inspection function does not hinder or flop the basic operations of the In-line mode system. From a proto-type NP-based NIDS implemented at a PC platform with an x86 processor running Linux, two Gigabit Ethernet ports, and 2.5Gbps Agere PayloadPlus(APP) NP solution, the experiment results show that our proposed scheme can reliably filter and meter the full traffic of two gigabit ports at the first level even though it can inspect the packet payload up to 320 Mbps in real-time at the second level, which can be compared to the performance of general-purpose processor based Inspection. However, the simulation results show that the deep packet searching is also possible up to 2Gbps in wire speed when we adopt 10Gbps APP solution.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.11-23
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• 2011

The objective of this paper is to develop a daily pattern clustering algorithm using historical traffic data that can reliably detect under various traffic flow conditions in urban streets. The developed algorithm in this paper is categorized into two major parts, that is to say a macroscopic and a microscopic points of view. First of all, a macroscopic analysis process deduces a daily peak/non-peak hour and emphasis analysis time zones based on the speed time-series. A microscopic analysis process clusters a daily pattern compared with a similarity between individuals or between individual and group. The name of the developed algorithm in microscopic analysis process is called "Two-step speed clustering (TSC) algorithm". TSC algorithm improves the accuracy of a daily pattern clustering based on the time-series speed variation data. The experiments of the algorithm have been conducted with point detector data, installed at a Ansan city, and verified through comparison with a clustering techniques using SPSS. Our efforts in this study are expected to contribute to developing pattern-based information processing, operations management of daily recurrent congestion, improvement of daily signal optimization based on TOD plans.