• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.11
• /
• pp.141-149
• /
• 2013

IETF 6LoWPAN standard technique has been studied in IoT environment to support the IPv6 packet communication. 6LoWPAN protocol for transmission of packets mainly in the AODV routing protocol and a variety of extended techniques have been investigated. In particular, consisting of nodes with limited resources in a network error occurs when the 6LoWPAN reliable data transfer and fast routing method is needed. To this end, in this paper, we propose resilient routing protocol and extension of IETF LOAD algorithm, for optimal recovery path, More specifically, the optimal recovery path setup algorithm, signal flow, and detailed protocols for the verification of the reliability of packet transmission mathematical model is presented. The proposed protocol techniques to analyze the performance of the NS-3 performance through the simulation results that is end-to-end delay, throughput, packet delivery fraction and control packet overhead demonstrated excellence in comparison with existing LOAD.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.4C
• /
• pp.338-346
• /
• 2012

Wireless sensor network (WSN) technology provides a variety of medical and healthcare solutions to assist detection and communication of body conditions. However, data reliability inside WSN might be influenced to healthcare routing protocol due to limited hardware resources of computer, storage, and communication bandwidth. For this reason, we have conducted various wireless communication experiments between nodes using parameters such as RF strength, battery status, and deployment status to get a optimal performance of mobile healthcare routing protocol. This experiment may also extend the life time of the nodes. Performance analysis is done to obtain some important parameters in terms of distance and reception rate between the nodes. Our experiment results show optimal distance between nodes according to battery status and RF strength, or deployment status and RF strength. The packet reception rate according to deployment status and RF strength of nodes was also checked. Based on this performance evaluation, the optimized sensor node battery and deployment in the developed our mobile healthcare routing protocol were proposed.

• Journal of Sensor Science and Technology
• /
• v.32 no.2
• /
• pp.110-117
• /
• 2023

Reconstructing underwater geometry in real time with forward-looking sonar is critical for applications such as localization, mapping, and path planning. Geometrical data must be repeatedly calculated and overwritten in real time because the reliability of the acoustic data is affected by various factors. Moreover, scattering of signal data during the coordinate conversion process may lead to geometrical errors, which lowers the accuracy of the information obtained by the sensor system. In this study, we propose a three-step data processing method with low computational cost for real-time operation. First, the number of data points to be interpolated is determined with respect to the distance between each point and the size of the data grid in a Cartesian coordinate system. Then, the data are processed with a nonlinear interpolation so that they exhibit linear properties in the coordinate system. Finally, the data are transformed based on variations in the position and orientation of the sonar over time. The results of an evaluation of our proposed approach in a simulation show that the nonlinear interpolation operation constructed a continuous underwater geometry dataset with low geometrical error.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.3C
• /
• pp.255-263
• /
• 2010

In this paper, we present an efficient cooperative transmission scheme for high speed 60GHz WPAN system. In 60GHz, the cooperative transmission with relay is effective scheme because signals are exceedingly attenuated according to the distance and the transmission is impossible when there is no LOS between transmitter and receiver. Moreover, the reliability of signal in destination can be improved by receiving data from a relay as well as a transmitter. However, the overall data rate is reduced because transmission time is more required for relay. To solve this problem, we propose a cooperative transmission scheme with RS-CC serial concatenated codes. In the proposed cooperative transmission scheme, the relay can reduce the transmission data size because the only parity bits of systematic RS code are transmitted after encoding by CC. But the computational complexity is increased at the relay and the destination.

• Journal of Digital Convergence
• /
• v.14 no.6
• /
• pp.489-498
• /
• 2016

The purpose of this study was to evaluate selective attributes importance and satisfaction of University Ski Lecture Environment that students perceive using IPA method. In order to achieve this goal, a questionnaire was used to gather data, and the convenient sampling method was used to select 300 members from three pertinent university in Seoul and Chungcheong-do, Gyeongsang-do Province as participants of this study. Only data from 221 respondents however were used after screening data for reliability, and SPSS for Windows(21.0 version) statistical program was used to conduct descriptive analysis, factor analysis, reliability analysis, paired samples t-test analysis, independent samples t-test analysis and IPA matrix analysis. The following results were obtained. First, significant differences between the level of satisfaction and the level of importance were found for part of the selection attributes for each group. Second, Iquadrant was included with meals and information provided factors. IIquadrant was included with instructors and class program, information provided, accommodation factors. IIIquadrant was included in accommodation and meals, time-distance factors. IVquadrant was included in the information provided factor.

• Korea Journal of Hospital Management
• /
• v.11 no.1
• /
• pp.110-126
• /
• 2006

The purpose of the study is to find the factors influencing small or middle size clinics and hospitals CEOs' expectation level on the affiliation with the large size teaching hospitals. Data for analysis was collected to use self-administrative structured questionnaire on 164 CEOs of small or middle sized clinics and hospitals affiliated with large sized teaching hospital located in Kyung Ki Province. For the study, the researchers develop the constructs for questions on the expectation on the affiliation, the attitude such as confidence, knowledge on the affiliation, previous relationship of the affiliation, and selection guideline of the affiliation with exploratory factor analysis and reliability test. Through the confirmative factor analysis using AMOS 4, the researchers develop constructs based on exact relationship between constructs and questions. CEOs' expectation level on the affiliation is influenced on attitude or confidence, gender, types of clinics and hospitals, distance to the affiliated large hospital, types of recommender, and number of affiliated hospitals. Large sized hospitals that want to affiliation with other clinics and hospitals can promote the affiliation to consider these factors from the results.

• Journal of Communications and Networks
• /
• v.14 no.4
• /
• pp.451-460
• /
• 2012

Natural disasters often lead to regional failures that can cause network nodes and links co-located in a large geographical area to fail. Novel approaches are required to assess the network vulnerability under such regional failures. In this paper, we investigate the vulnerability of networks by considering the geometric properties of regional failures and network nodes. To evaluate the criticality of node locations and determine the critical areas in a network, we propose the concept of ${\alpha}$-critical-distance with a given failure impact ratio ${\alpha}$, and we formulate two optimization problems based on the concept. By analyzing the geometric properties of the problems, we show that although finding critical nodes or links in a pure graph is a NP-complete problem, the problem of finding critical areas has polynomial time complexity. We propose two algorithms to deal with these problems and analyze their time complexities. Using real city-level Internet topology data, we conducted experiments to compute the ${\alpha}$-critical-distances for different networks. The computational results demonstrate the differences in vulnerability of different networks. The results also indicate that the critical area of a network can be estimated by limiting failure centers on the locations of network nodes. Additionally, we find that with the same impact ratio ${\alpha}$, the topologies examined have larger ${\alpha}$-critical-distances when the network performance is measured using the giant component size instead of the other two metrics. Similar results are obtained when the network performance is measured using the average two terminal reliability and the network efficiency, although computation of the former entails less time complexity than that of the latter.

• Korean Journal of Geomatics
• /
• v.2 no.1
• /
• pp.47-55
• /
• 2002

Remote sensing is the science and art of obtaining information about an object, area or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area, or phenomenon under investigation./sup 1)/ EOC (Electro -Optical Camera) sensor loaded on the KOMPSAT-1 (Korea Multi- Purpose Satellite-1) performs the earth remote sensing operation. EOC can get high-resolution images of ground distance 6.6m during photographing; it is possible to get a tilt image by tilting satellite body up to 45 degrees at maximum. Accordingly, the device developed in this study enables to obtain images by photographing one pair of tilt image for the same point from two different planes. KOMPSAT-1 aims to obtain a Korean map with a scale of 1:25,000 with high resolution. The KOMPSAT-1 developed automated feature extraction system based on stereo satellite image. It overcomes the limitations of sensor and difficulties associated with preprocessing quite effectively. In case of using 6, 7 and 9 ground control points, which are evenly spread in image, with 95% of reliability for horizontal and vertical position, 3-dimensional positioning was available with accuracy of 6.0752m and 9.8274m. Therefore, less than l0m of design accuracy in KOMPSAT-1 was achieved. Also the ground position error of ortho-image, with reliability of 95%, is 17.568m. And elevation error showing 36.82m was enhanced. The reason why elevation accuracy was not good compared with the positioning accuracy used stereo image was analyzed as a problem of image matching system. Ortho-image system is advantageous if accurate altitude and production of digital elevation model are desired. The Korean map drawn on a scale of 1: 25,000 by using the new technique of KOMPSAT-1 EOC image adopted in the present study produces accurate result compared to existing mapping techniques involving high costs with less efficiency.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.4
• /
• pp.101-110
• /
• 2011

A smart grid networks delivers electricity from suppliers to consumers using digital technology with two-way communications to control appliances at consumers' homes to save energy, reduce cost and increase reliability and transparency. Security is critically important for smart grid networks that are usually used for the electric power network and IT environments that are opened to attacks, such as, eavesdroping, replay attacks of abnormal messages, forgery of the messages to name a few. ZigBee has emerged as a strong contender for smart grid networks. ZigBee is used for low data rate and low power wireless network applications. To deploy smart grid networks, the collected information requires protection from an adversary over the network in many cases. The security mechanism should be provided for collecting the information over the network. However, the ZigBee protocol has some security weaknesses. In this paper, these weaknesses are discussed and a method to improve security aspect of the ZigBee protocol is presented along with a comparison of the message complexity of the proposed security protocol with that of the current ZigBee protocol.

• Journal of Advanced Navigation Technology
• /
• v.20 no.6
• /
• pp.588-594
• /
• 2016

As more populations are getting older, the number of vulnerable pedestrians is increasing, thereby social problems related to transportations also frequently occur in different areas and situations. Many of such problems come from bus drivers who may pass bus stops not recognizing passengers about to board. In this paper, we propose a new IoT bus notification system developed to avoid these situations. Our implementation aims to gain bus service routes using publicly opened data, notify passengers about bus stop locations using GPS information and finally deliver the positions of those passengers to the bus drivers so that they can hardly miss passengers who are willing to board on the right stop. By creating an application, it was conducted by means of a GPS to communicate the location of the vehicle by means of GPS and transfer data to the location of the vehicle. Experimental results show that it is possible to accurately determine the position of passengers even in a crowded race area. The average error distance is 31m, and if the data to be processed as error is excluded, it provides a high reliability as 19m.