• The Journal of the Korea Contents Association
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• v.7 no.1
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• pp.147-154
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• 2007

In this paper, we propose a new parallel search algorithm to acquire synchronization for UWB(Ultra Wideband) systems that reduces computation of the correlation. The conventional synchronization acquisition algorithms check all the possible signal phases simultaneously using multiple correlators. However it reduces the acquisition time, it makes high power consumption owing to increasing of correlation. The proposed algorithm divides the preamble signal to input the correlator into an m-bit bunch. We check the result of the correlation at first stage of an m-bit bunch data and predict whether it has some synchronization acquisition information or not. Thus, it eliminates the unnecessary operation and save the number of correlation. We evaluate the proposed algorithm under the AWGN and the multi-Path channel model with MATLAB. The proposed parallel search scheme reduces number of the correlation 65% on the AWGN and 20% on the multi-path fading channel.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1131-1142
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• 2013

This study aims to verify the applicability of TRANSIMS (TRansportion ANalysis SIMulation System) in interrupted traffic flow through calibration and validation process based on observation data; such as headway, traffic volume, speed, and travel time from Dalguberl Boulevard in Dae-gu metropolitan city. On this study, several micro-simulation parameters are derived from the calibration and validation process through performing a headway comparison and applying an ID back tracking methodology. As a result, it is figured out that actual circumstances of Korean roadway; for example, traffic volume per lane, speed, and travel time, can be applied on the TRANSIMS. Especially, it was possible to find out the influence of cell size parameter to traffic flow characteristic of simulation. However, it is hard to conclude that TRANSIMS is applicable to Korean roadway environment with studying particular target area. Therefore, additional studies; such as more case studies with various types of road, signal, and land use, will be required to localize TRANSIMS to Korea.

• Journal of Korean Society of Transportation
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• v.21 no.4
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• pp.79-90
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• 2003

Internal metering policy(IMP) is a control strategy to improve the quality of traffic flow within a network by avoiding queue spillback or intersection blockage. It is a more aggressive control strategy than the current control strategy employed in COSMOS. A preliminary study was made to incorporate the IMP logic within the COSMOS system to improve its' functionality at oversaturated conditions. From the study results, a set of guideline for real implementation was recommended : traffic conditions, detector configurations, and control procedures, etc. A simulation study was performed to evaluate the effectiveness of the proposed guidelines. It was shown that the occurrence of queue spillback was minimized. and overall network performance was also improved by applying IMP logic as compared to COSMOS control onl.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.10-14
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• 2015

Recently, the collection of the sensor data and its analysis become important as the smart buildings equipped with the various sensors appear as a usual scene. The interconnection through the wire cable among the sensors is indispensible because of the information collections such as the temperature, the humidity, and the luminance in the rooms and the hallways for the effective management of the in-building energies. However, these interconnections through the cabling will be very costly, time-consuming, and a difficult task since they will cause some damages to the buildings. Therefore, the interconnections through the unwired connections are required in terms of the deployment effectiveness such as time and cost In this paper, the design and the short sequence operation appropriateness are confirmed through the simulation of the signal measurement system for in-building propagation characteristics based on short signature sequence and the analysis of the system characteristics based on the false alarm probability is performed thereafter.

• Journal of Broadcast Engineering
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• v.23 no.6
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• pp.813-823
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• 2018

UHD content is characterized by higher bandwidth requirements to provide seamless playback. The existing HTTP adaptive streaming scheme periodically requests video segment of lower quality than the available bandwidth in the steady state. In the steady state, the On-Off pattern is repeated due to the difference of the available bandwidth and the encoding rate of the content. And the repeated Off interval is causing the problem that can not efficiently use the available bandwidth. In the wireless environment where the delay and loss rate are higher with large bandwidth fluctuations, this problem is exacerbated because the available bandwidth is estimated inaccurately. Therefore, in this paper, we propose a segment scheduling scheme for efficient bandwidth utilization of UHD contents streaming in wireless environment. Proposed scheme is a group segment that simultaneously reqeusts multiple segments in one request message in order to reduce frequency of OFF interval. Through simulation, Our scheme improves bandwidth utilization.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.100-109
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• 2021

Flooding usually brings in disruptions and aggravated congestions to the roadway network. Hence, right information should be provided to road users to avoid the flood-impacted areas and for city officials to recover the network. However, the information about individual link congestion may not be conveyed to roadway users and city officials because too many links are congested at the same time. Therefore, more significant information may be desired, especially in a disastrous situation. This information may include 1) which places to avoid during flooding 2) which places are feasible to drive avoiding flooding. Hence, this paper aims to develop a framework to identify the flood-impacted areas in a roadway network and their criticality. Various impacted clusters and their spatiotemporal properties were identified with field data. From this data, roadway users can reroute their trips, and city officials can take the right actions to recover the affected areas. The information resulting from the developed framework would be significant enough for roadway users and city officials to cope with flooding.

• Journal of Advanced Navigation Technology
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• v.25 no.6
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• pp.517-522
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• 2021

Optical dispersion-managed link combined with optical phase conjugation for compensating of the distorted optical signals due to chromatic dispersion and nonlinear effects, which is required to implement long-haul wavelength division multiplexed system, is proposed and assessed in viewpoint of network topology flexibility. Optical phase conjugator capable to compensate for the distorted optical signal due to nonlinear effects is placed non-midway of total transmission distance. And, in dispersion-managed link, residual dispersion per span (RDPS) of each fiber spans in former half section and latter half section with respect to optical phase conjugator are different to each other. Simulation results show when the RDPS of each fiber sections in one half section makes it's own net residual dispersion slight different from another half section's net residual dispersion, the compensation effect in the proposed link configuration is more increased.

• Journal of KIISE
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• v.44 no.2
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• pp.213-222
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• 2017

The Internet of Things (IoT) technology is rapidly developing in recent years, and is applicable to various fields. A smart factory is one wherein all the components are organically connected to each other via a WSN, using an intelligent operating system and the IoT. A smart factory technology is used for flexible process automation and custom manufacturing, and hence needs adaptive network management for frequent network fluctuations. Moreover, ensuring the timeliness of the data collected through sensor nodes is crucial. In order to ensure network timeliness, the power consumption for information exchange increases. In this paper, we propose an IEEE 802.15.4e DSME-based distributed scheduling algorithm for mobility support, and we evaluate various performance metrics. The proposed algorithm adaptively assigns communication slots by analyzing the network traffic of each node, and improves the network reliability and timeliness. The experimental results indicate that the throughput of the DSME MAC protocol is better than the IEEE 802.15.4e TSCH and the legacy slotted CSMA/CA in large networks with more than 30 nodes. Also, the proposed algorithm improves the throughput by 15%, higher than other MACs including the original DSME. Experimentally, we confirm that the algorithm reduces power consumption by improving the availability of communication slots. The proposed algorithm improves the power consumption by 40%, higher than other MACs.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.2
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• pp.29-40
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• 2010

Car simulation by TRANSIMS is able to rapidly analyze the broad area based on CA(Cellular Automata) theory, which is the great advantage compared to other existing programs. As the source code of TRANSIMS is open, it may be modified by incorporating the network and traffic characteristics. This study uses the traffic thematic map built in the Korean National Traffic DB(KTDB) center among input date used for building network data of TRANSIMS. However, because the traffic thematic map is not composed as the type required by TRANSIMS, it was corrected and complemented to build a network, and the traffic volume at arterial roads and the traffic volume at each direction of the intersection was calculated through simulation for the area of Suseong-Gu, Daegu Metro. This was compared to the actual traffic volume. As a result of the simulation, it shows error from 14% to 42% at intersection, and from 3% to 8% at arterial roads. This result is very satisfactory because the entire traffic volume of Daegu Metro was not considered, and the tendency of drivers avoiding path due to construction on certain section, the status of road surface and chronic congestion was not reflected.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.6
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• pp.10-21
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• 2010

In the cluster-tree network which covers wide area network and has many nodes for monitoring purpose traffic is concentrated around the sink. There are long transmit delay and high data loss due to the intensive traffic when IEEE 802.15.4 is adapted to the cluster-tree network. In this paper we propose Dynamic Channel Allocation algorithm which dynamically allocates channels to increase the channel usage and the transmission success rate. To evaluate the performance of DCA, we assumed the monitoring network that consists of a cluster-tree in which sensing data is transmitted to the sink. Analysis uses the traffic data which is generated around the sink. As a result, DCA is superior when much traffic is generated. During the experiment assuming the least amount of traffic, IEEE 802.15.4, has the minimum length of active period and 90% data transmission success rate. However DCA maintains 11.8ms of active period length and results in 98.9% data transmission success rate.