• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.47-53
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• 2012

In general, it is essential that contents are to be provided with proper bitrate according to network conditions in order to support higher quality of video streaming services over wired and wireless networks. Recently, DASH is adopted by the MPEG as the standard for HTTP based adaptive streaming technology and consists of the server and clients. The clients should parse XML files from the server and play contents after accessing the finely divided segments into various bitrates. In this paper, we designed a Smart AP(Access Point) which exists between DASH contents server and Non-DASH clients enables provide DASH services to Non-DASH clients. In addition, proposed Smart AP provides DASH service to various types of clients as maintaining the existing environment without additional development costs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.534-537
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• 2006

Currently, The fast development which radio communication technique is creating new services from the industry sector which is various from convenient characteristic and the ease characteristic side. Specially, rise and development of the radio communication technique which is various from environment monitor ring field makes to be improved about sharp curtailment of establishment and logistics relation expense, and collection period of the data which occurs real-time from site, reliability and delivery characteristic. But continuous application and the success about the environment monitor ring field of radio communication technique will be able to trust And It is important to provide time information which is appropriate real-time. So this paper plans the sensor network based on environment measurement watch which applies a radio communication technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1554-1560
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• 2015

802.11p WAVE is the next-generation wireless communication that can make Ad-hoc network communication possible for Vehicle-to-Vehicle. GBSR protocol, one of the 802.11p WAVE protocols, mainly focuses on improvements in networks that have a tendency to disconnect. However, it does not consider the transmission time and velocity of a packet thus, there is a disadvantage of there being a delay in the transmission velocity, in urgent situations like car accidents, emergency patients transportation and crimes. In this paper, we proposed A-GBSR protocol for transmission of a packet to mobile node which has a high speed through the improved beacon message and Adaptive Neighbor list Management that are considering of the GBSR protocol transmission velocity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2526-2533
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• 2015

In this paper, a design method for a compact dual-band coplanar waveguide-fed slot antenna using SRR(split-ring resonator) conductor is studied. The SRR conductor is loaded inside a rectangular slot of the proposed antenna for dual-band operation. When the SRR conductor is inserted into the slot, the original rectangular slot is divided into a rectangular loop region and a rectangular slot region, and frequency bands are created by the loop and slot, separately. A prototype of the proposed dual-band slot antenna operating at 2.45 GHz WLAN band and 3.40-5.35 GHz band is fabricated on an FR4 substrate with a dimension of 30 mm by 30 mm. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.38-2.51 GHz and 3.32-5.38 GHz for a voltage standing wave < 2, and measured gain is 1.7 dBi at 2.45 GHz, and it ranges 2.4-3.2 dBi in the second band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.339-346
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• 2011

In the existing RF communication based WPAN environment, a lowering of battery span and interference problem among sensors occur because the value of output is set and transmitted steadily when the system on sensor is initialized. Therefore, this paper proposes a framework and a transmit method with low power which decreases the electricity consumption by properly controling transmit power of opponent by received signal strength indicator(RSSI) of each sensor. The system proposes a power-lowering method by controling transmit power properly by the transmit intensity of the connected sensor after being affected by the transmit intensity of surrounded sensor. The framework that is proposed in this paper includes data transmit module, transmit power manager module, transmit power searching module, signal transmit module, and signal receiving module.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.1-11
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• 2006

It is possible to track the moving vehicle as well as to develop the location based services actively according to the progress of wireless telecommunication and GPS, to the spread of network, and to the miniaturization of cellular phone. To provide these location based services, it is necessary for an index technique to store and search too much moving object data rapidly. However the existing indices require a lot of costs to insert the data because they store every position data into the index directly. To solve this problem in this paper, we propose a buffer node operation and design a GU-tree(Group Update tree). The proposed buffer node method reduces the input cost effectively since the operation stores the moving object location data in a group, the buffer node as the unit of a non-leaf node. hnd then we confirm the effect of the buffer node operation which reduces the insert cost and increase the search performance in a time slice query from the experiment to compare the operation with some existing indices. The proposed tufter node operation would be useful in the environment to update locations frequently such as a transportation vehicle management and a tour-guide system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.889-896
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• 2007

Advances in wireless networking, micro-fabrication and integration, and embedded microprocessors have enabled a new generation of massive-scale sensor networks. Because each sensor node is limited in size and capacity, it is very important to design a new simple and energy efficient protocol. Among conventional sensor networks' routing protocols, the directed diffusion scheme is widely blown because of its simplicity. This scheme, however, has a defect in that sending interest and exploratory data messages while setting connection paths consumes much energy because of its flooding scheme. Therefore, this paper proposes a new sensor network routing protocol, called sequenced directed diffusion with a threshold control, which compromises the conventional directed diffusion scheme's defect and offers an energy efficient routing idea. With a computer simulation, its performance is evaluated and compared to the conventional directed diffusion scheme. Numerical results show that the proposed scheme offers energy efficiency while routing packets, and resolves ill-balanced energy consumption among sensor nodes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.2119-2124
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• 2008

An information-oriented basis in today's society has been changing fast, and the desire for connectivity has caused an exponential growth in wireless communication and sensor network. Sensor networks using RFID, in particular, have led this trend due to the increasing exchange of data in Ubiquitous such as the home RF, access control system, U-Healthcare, and Logistics information Systems. Also, the RFID when it applies a technique, is able to raise the stability of shipping as controling the mobile course and an entrance and exit of the crews an well as previously preventing an accident from shipping. In this paper, we designed and implemented personnel control system using UHF-RFID in vessels which shows through host PC reading and writing tag.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.436-444
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• 2016

The primary windings of the main transformer for rolling stock have several natural frequencies that can occur internal resonance with transient voltages induced on a high voltage feeding line. Factory testing is limited in its ability to determine whether or not transient voltage with various shape and duration can be excitable. This study presents the design of a high voltage windings model and simulation and analysis of the internal resonant characteristics in terms of the initial voltage distribution and voltage-frequency relationship using the electromagnetic transients program (EMTP). Turn-based lumped-parameters are calculated using the geometry data of the transformer. And, sub-models, being grouped into the total number of layers, are composed using a ladder-network model and implemented by the library function of EMTP. Case studies are used to show the layer-based voltage-frequency relationship characteristics according to the frequency sweep and the voltage escalation and distribution aspects in time-domain simulation.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.8
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• pp.201-208
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• 2019

Intra-Body Communication (IBC) is a communication method using the human body as a communication medium. The fact that our human body consists of water and electrolyte allow such communication method could work and have strength in low-power. However, because the IBC directly affects to human body by using it as a medium, there was a lack of research in communication protocols of each communication layer. In this paper, we suggests MAC parameters which affects the performance of communication in human body channel, and propose new MAC protocol. Our results shows that our MAC is suitable for supporting high data rate applications with comparable radio duty cycle performance.