• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.5
• /
• pp.85-90
• /
• 2017

Indoor location-based services have been developed based on the Internet of Things technologies which measure and analyze users who are moving in their daily lives. These various indoor positioning technologies require separate hardware and have several disadvantages, such as a communication protocol which becomes complicated. Based on the fact that a reduction in signal strength occurs according to the distance due to the physical characteristics of the transmitted signal, RSSI technology that uses the received signal strength of the wireless signal used in this paper measures the strength of the transmitted signal and the intensity of the attenuated received signal and then calculates the distance between a transmitter and a receiver, which requires no separate costs and makes to implement simple measurements. It was applied calculating the value for the average RSSI and the RSSI filtering feedback. Filtering is used to reduce the error of the RSSI values that are measured at long distance.It was confirmed that the RSSI values through the average filtering and the RSSI values measured by setting the coefficient value of the feedback filtering to 0.5 were ranged from -61 dBm to - 52.5 dBm, which shows irregular and high values decrease slightly as much as about -2 dBm to -6 dBm as compared to general measurements.

• Land and Housing Review
• /
• v.7 no.3
• /
• pp.131-136
• /
• 2016

The aim of this study was to improve the performance of hybrid energy harvesting block merge the vibrations and the pressure developed in the previous study. The power generation performance of the energy block improved in this manner was measured and compared with the energy performance of the products previously developed. In previous models, the center has placed a piezoelectric, the two sides had arranged a vibration applying electromagnetic inducing type. Improved model was disposed three in a row of three unit modules for one block. We change the design in the following way. That is, a unit module has been placed the upper piezoelectric body, the lower portion were arranged three electron donation. In laboratory conditions, the power generation performance evaluation results of the improved energy block is as follows. Once when the vibration, power generation was determined to 1.066W. When compared with previous studies, and power generation performance is improved up to 235%. When the vibration in a row 5, power generation was determined to 1.830W. When compared with previous studies, the performance is improved to 177%. The purpose of developing a hybrid energy block is intended to produce electricity by the pressure and vibration when a vehicle passes through the energy block installed in the car park the mouth portion. Electricity produced will try to take advantage of for the purpose of operating a guiding beacon and LED signage in the parking lot entrance. Therefore, it is determined that there is a need in the experiment to compare the performance of the power generation in the field.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2012.10a
• /
• pp.27-30
• /
• 2012

In the Cluster-Based Routing Protocol (CBRP) a cluster header in each cluster should be elected. The cluster headers consume energy much more than other nodes because they manage and operate all of mobile nodes in their cluster. The traditional CBRP elects a cluster header without considering the remaining electric energy of each node. So, there exists problems that the cluster header has short average lifetime, and another cluster header should be elected again frequently. In this paper, we propose the improved protocol which prolongs the lifetime of the cluster header, decreases of header re-elected problem, decreases of header re-elected problem and enhances the stability of the path. In order to achieve this, when a cluster header is elected in a cluster, the remaining electric energies of all the nodes are compared with one another, and the node with the highest energy is elected as the cluster header. Also, the node with the second highest energy is elected as the second header. If the elected cluster header is unable to perform the role of the cluster header because the remaining energy level goes low, it sends a beacon message to neighbor member nodes and the second header will serve as the cluster header.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37B no.12
• /
• pp.1195-1207
• /
• 2012

Fast and reliable message broadcasting is critical for safety critical applications of VANET due to the urgency and/or significance of the messages for passengers and drivers. For reliable message delivery, a mechanism for checking the reception of message at the neighboring vehicles and retransmitting it if necessary is required. Especially, in urban environments, where the traffic density tends to be high, mechanisms that minimize control message overhead such as beacon are appropriate in order to minimize the message collisions. Furthermore, broadcast delivery is especially difficult at the intersection due to the road side obstacles such buildings, and hence, a mechanism that enables effective and efficient delivery across intersections is required. In this paper, we propose a beaconless reliable and efficient broadcast approach which specifically taking into account the urban streets. The proposed approach checks the message reception of neighboring vehicles implicitly by taking into account the broadcast of message by next vehicle as the acknowledgement. When retransmissions is necessary around the intersections, vehicles located within the intersection area, where the chance of successful signal propagation toward every branch of the intersection is higher due to less signal attenuation caused by road side obstacles, are to do the retransmissions. Simulation results show that the proposed approach can provide better reliability while consume less resources than the existing approaches.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.11C
• /
• pp.1098-1105
• /
• 2009

In this paper, we propose an asynchronous UWB (Ultra Wide Band) Positioning scheme that can provide precise positioning performance with low complexity and low power consumption. We also present the residual test to improve the positioning performance in multipath channels having heavy NLoS (Non-Line of Sight) components. As compared to conventional ToA (Time of Arrival) positioning scheme that requires round-trip transmissions as many as the number of beacons, the proposed UWB positioning scheme effectively decrease power consumption and processing delay since a single round-trip transmission is only required. Also, as compared to conventional TDoA (Time Difference of Arrival) positioning scheme requiring precise synchronization among the beacons, asynchronous nature of the proposed scheme achieves very low system complexity. Through simulations in LoS (Line of Sight) channel models, we observe that the proposed scheme requires low system complexity, low power consumption, while providing positioning performance of almost the same accuracy as the conventional ToA and TDoA positioning schemes. In addition, the proposed scheme by employing the residual test achieves accurate positioning performance even in multipath channels having heavy NLoS components.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.1 no.1
• /
• pp.41-51
• /
• 2002

As Advanced Traveler Information System(ATIS) is the kernel of the Intelligent Transportation System, it is very important how to manage data from traffic information collectors on a road and have at borough grip of the travel time's change quickly and exactly for doing its part. Link travel time can be obtained by two method. One is measured by area detection systems and the other is estimated by point detection systems. Measured travel time by area detection systems has the limitation for real time information because it Is calculated by the probe which has already passed through the link. Estimated travel time by point detection systems is calculated by the data on the same time of each. section, this is, it use the characteristic of the various cars of each section to estimate travel time. For this reason, it has the difference with real travel time. In this study, Artificial Neural Networks is used for estimating link travel time concerned about the relationship with vehicle detector data and link travel time. The method of estimating link travel time are classified according to the kind of input data and the Absolute value of error between the estimated and the real are distributed within 5$\~$15minute over 90 percent with the result of testing the method using the vehicle detector data and AVI data of Namsan Tunnel $\#$1. It also reduces Time lag of the information offered time and draws late delay generation and dissolution.

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

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.29 no.1
• /
• pp.125-152
• /
• 2018

This study examined users' awareness to establish futurity of libraries and to propose strategies in the era of the $4^{th}$ Industrial Revolution. For this purpose, the awareness survey was conducted of users, and the survey consisted of questions about the awareness of the $4^{th}$ Industrial Revolution, the current state of using technologies and devices of the $4^{th}$ Industrial Revolution, and the futurity of libraries of the $4^{th}$ Industrial Revolution. The results are as follows: First, users were interested in the $4^{th}$ industrial Revolution, but they thought that new technologies are poorly adopted in the libraries. Second, users were most frequently using mobile phone, QR code, and Beacon. Especially, mobile phone was a most frequently used device in the libraries. However, users were not satisfied with technologies and devices provided by the libraries. Third, users expected the $4^{th}$ Industrial Revolution have a positive influence on future of libraries, but they were worried about losses of opportunities and jobs. Forth, users agreed with necessity of new technologies of the $4^{th}$ Industrial Revolution for libraries services. They wanted application of the technologies, expecially, in online services. Ultimately, this study suggested some meaningful insights and strategies through comparative analysis of the above findings and librarians' awareness survey results.

• The KIPS Transactions:PartC
• /
• v.16C no.1
• /
• pp.91-100
• /
• 2009

Given the increased interest in ubiquitous computing, wireless sensor network has been researched widely. The localization service which provides the location information of mobile user, is one of important service provided by sensor network. Many methods to obtain the location information of mobile user have been proposed. However, these methods were developed for only one mobile user so that it is hard to extend for multiple mobile users. If multiple mobile users start the localization process concurrently, there could be interference of beacon or ultrasound that each mobile user transmits. In the paper, we propose IAL, the localization technique with interference avoidance for multiple mobile nodes in mobile wireless sensor networks. In IAL, interference is prevented by forcing the mobile node to get the permission of localization from anchor nodes. For this, we define LIP packet type for localization initiation by mobile node and LGP packet type for localization grant by anchor node. LRP packet type is used to reject localization by anchor node for interference avoidance. The experimental result shows that the number of interference between nodes are increased in proportion to the number of mobile nodes and IAL provides efficient localization.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.1
• /
• pp.63-71
• /
• 2013

In the Cluster-Based Routing Protocol (CBRP) a cluster header in each cluster should be elected. The cluster headers consume energy much more than other member nodes do because they manage and operate all of mobile nodes in their cluster. The traditional CBRP elects a cluster header without considering the remaining electric energy of each node. So, there exist problems that the cluster header has short average lifetime, and a new cluster header should be elected again frequently. In this paper, we propose the improved protocol which prolongs the lifetime of the cluster header, decreases the problem of re-electing the cluster header and enhances the stability of the path. In order to achieve this, when a cluster header is elected in a cluster, the remaining electric energies of all the nodes are compared with one another, and the node with the highest energy is elected as the cluster header. Also, the node with the second highest energy is elected as the second header. If the elected cluster header is unable to perform the role of the cluster header any more because the remaining energy level goes low, it sends a beacon message to neighbor member nodes, then the second header will serve as the cluster header.