• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.53-64
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• 2009

For a realization of the ubiquitous society, applying IT to vehicle industry has recently been an attractive issue to make wireless communication in body area network possible to everywhere. In this paper, we propose the physical layer symbol structure based on PPM scheme of the IEEE 802.15.4a for the off-body high data rate WBAN system. We propose four symbol structures which is classified according to the number of the chip and whether the channel coding is used or not. We calculate the required SNR through the link budget calculation and the recently proposed off-body WBAN channel environment was applied in the simulation. The results of four systems show that small number of burst's chip enhances the performance and the system is capable to achieve the data rate of 10 Mbps.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.57-63
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• 2012

Effective use of stethoscope is very important for primary clinical diagnosis for the increasing cardiovascular and respiratory disease. This study developed the contact vibration sensor using piezopolymer film which minimizes the ambient noise, and signal processing algorithm was applied for providing better auscultation sounds compare to the existing electronic stethoscopes. Especially, low frequency heart sounds were acquired without distortion, and the quality of lung sounds were improved. Also, auscultating sounds could be transmitted using bluetooth, which made possible to be used for the u-healthcare environment. Results of this study, auscultation of heart and lung sounds, could be applied to the convergence industry of medical and information communication technology through remote diagnosis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.7-12
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• 2014

The data forwarding transmission is an important function of the relay in cooperative communication in wireless communication systems. However, additional relay cause the waste of power consumption and cost. Therefore, in this paper, we consider how to use the user mobile devices in stead of relays to deal with this problem. In this paper, we proposed the protocol that divide each relay into two states of idle and non-idle. The receiver has two functions of base station and user mobile device. In this case, it is possible that no additional cost, and improve the spectral efficiency and network capacity. We verified BER performance for the proposed protocol over Rayleigh fading through Monte-Carlo simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.53-58
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• 2017

UFMC is known as the one among novel multi-carrier modulation techniques which are designed for replacing OFDM for 5G wireless communication systems. It is the generalized model of OFDM and FBMC, which combines the advantages of OFDM and FBMC and avoids their weak points. UFMC is more robust in synchronization condition like Time-frequency misalignment compared to CP-OFDM. Moreover UFMC is more proper to burst uplink transmission like M2M 5G Communications. In this paper we analyze the BER performance in various channels and speeds. The simulation result shows that the BER performance is lowered when mobile devices are moving fast and the BER performance is so sensitive for the good channel environment.

• Spatial Information Research
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• v.18 no.4
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• pp.75-88
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• 2010

Recent development in wireless communication and mobile positioning technologies make geosensor networks widely used in the various fields of real world. As a result, much research has been done on the middleware that uses limited energy resources efficiently. However, because traditional middleware does not consider the characteristics of sensor node, such as computing power and specification, the existing middleware call not support the sensor nodes with only the restricted system resource. Therefore, in this paper, we design and implement a new Bytecode based Data Service Middleware supporting energy efficiency in geosensor networks. At first, the proposed middleware provides the optimized functions for sensor nodes by using minimum by tee ode instruction set and data manager supporting hardware abstraction. Secondly, the proposed middleware increases the energy efficiency of sensor node through both data aggregation query processing and data filtering that minimize data transmission by eliminating unnecessary data. Finally, we show from our performance analysis that the proposed middleware is more energy efficient than the existing SwissQM.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.8
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• pp.68-76
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• 1998

In this paper, a new morphological image segmentation algorithm of hierarchical structure by binary split is proposed. It splits a region with the lowest quality into two regions using only two markers having the highest contrast. Therefore, it improves the quality of image with limited regions and reduces contour information which is not sensitive to human visual system, when compared with the conventional algorithm. It is appropriate to PSTN, LAN, and mobile networks, of which the available transmission bandwidth is very limited, because the number of regions can be controlled. And the proposed algorithm shows very simple structure because it doesn't need post processing to eliminate small regions and reduces much computation by using only structuring element of small size at simplification step of each hierarchical structure when compared with the conventional algorithm.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.55-63
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• 2007

Multicast is an efficient transport mechanism for community communications and MANET is recently regarded as a promising solution for support ubiquitous computing as an underlying network technology. However, it is hard to deploy multicast mechanism into MANET owing to scarce resources in wireless networks and unpredictable changes in network topology. Several multicast mechanisms have been proposed in the literature to overcome the limitations. Especially, overlay multicasting schemes present several advantages over network based multicasting schemes. Yet, the overlay multicasting schemes still introduce redundant data transmissions that waste network bandwidth and battery of relay nodes. As a result the performance of the network is degraded. To reduce the redundancy, we propose an efficient way to construct an overlay structure as a multicast data delivery tree that utilizes a branch node which belongs to the tree. By using network simulation, we show that the proposed scheme presents higher packet delivery ratio and lower transmission cost than previously proposed schemes.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.97-104
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• 2020

In this paper, we propose a random number generator PP(PingPong256) and a shuffle technique to improve the problem that the encrypted image is damaged due to a lot of noise by the channel coding of wireless communication recommended in the special environment of space. The PP can constantly generate random numbers by entering an initial value of 512 bits. Random numbers can be encrypted through images and exclusive logical computations. Random numbers can be encrypted through images and exclusive logical computations. The shuffle technique randomly rearranges the image pixel positions while synchronizing the image pixel position and the random number array position and moving the random number arrangement in ascending order. Therefore, the use of PP and shuffle techniques in channel coding allows all pixels to be finely distributed and transmit high-quality images even in poor transmission environments.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1470-1475
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• 2009

Until now for the safety of structures and equipment monitoring technology to measure the amount of the physical, if that is the one, one-point or single-source target is one the most. Therefore, becoming more numerous and complex to measure the amount of physical measurement technology that is comprehensive and complex, multi-source concepts to the monitoring of a multi-sensing technology is required. Have the same characteristics of multi-source multi-use space such as a multi-structure of facilities/equipment is. The people's safety in a multi-use facility will be directly related to life and even a little carelessness can lead to large-scale disaster occurs because of several factors, risks and to manage detect in advance the development of an intelligent monitoring technology is essential. Therefore, this study shows that multiple structures/facilities to improve the quality of human life in research to maintain a safe and comfortable living space for multi-source intelligence to the development of monitoring technology to achieve that goal, and the ubiquitous sensor network system on the basis of the wireless transmission module, and multiple research facilities/equipment for the ultra-small sensors for health monitoring study was performed.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.4
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• pp.82-88
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• 2012

A VANET (Vehicular Ad Hoc Network), a subclass of MANET (Mobile Ad Hoc Network), is an ad hoc network using wireless communication between vehicles without fixed infrastructure such as base station. VANET suffers a frequent link breakage and network topology change because of the rapid movement of vehicles and the density change of vehicles. From these characteristics of VANET, geographical routing protocols such as GPSR (Greedy Perimeter Stateless Routing) using only the information of neighbor nodes are more suitable rather than AODV and DSR that are used in existing MANETs. However, GPSR may have a transmission delay and packet loss by frequent link disconnection and continual local maxima under the low vehicle density conditions. Therefore, in this paper, we propose a DTVR (Delay Tolerant Vehicular Routing) algorithm that perform a DTN-based routing scheme if there is no 2-hop neighbor nodes for efficient routing under the low vehicle densities in VANETs. Simulation results using ns-2 reveal that the proposed DTVR protocol performs much better performance than the existing routing protocols.