• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.636-644
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• 2009

This paper presents a compact, low insertion loss, sharp rejection and wide band microstrip band pass filter that is composed rectangular loop resonator and step-impedance-open-stub(SIOS) for wireless data communication. The SIOS can be reduce length about 30% more than general $0.25{\lambda}$ stub. And the stub can the advantage of tuning impedance magnitude. In order to demonstrate agrement of this paper prove, the optimized wide band pass filters are realized and experimented. A transmission line model used to calculate the frequency response of the new filters shows good agreement with measurements. The filter has 3dB fractional bandwith of 52.5%(3.267GHz), an insertion loss of better than 0.33dB from 4.587GHz to 7.854GHz, and two rejection of greater than 30dB within 221MHz$(4.366GHz{\sim}4.587GHz)$ at low frequency band, 181MHz$(7.854GHz{\sim}8.035GHz)$ at high frequency band. Maximum rejection characteristics of the filter are -54dB at low frequency and -60dB at high frequency.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.5
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• pp.1-6
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• 2011

LED(Light Emitting Diode) components have advantages of longer lifetime, lower power consumption and easy-to-control, compare to normal lamp and fluorescent light, according to the development of recent technologies. Thus, lots of illuminations which utilize LED components could be used. Recently, Visible Light Communication(VLC) which is a part of communication technologies, utilizing high speed response characteristic of LED components, started receiving public attention. In case of VLC, there is no need of frequency allocation due to no use of radio, but also no interference exists during data transmission, much different in ISM((Industrial Scientific Medical band). This is the reason why a lot of research results about VLC are becoming issued. In this paper, a survey of feasibility for using VLC utilizing an original LED illumination for underwater applications has been done and a primitive possibility of its application has been examined.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.124-131
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• 2014

This paper describes a design of an adaptive baseband modem based on TDMA(time division multiple access) with a relay protocol function for wireless personal area networks. The designed baseband modem is controlled by a master synchronization signal and can be configured a relay network up to 14 hops. For efficient data relay communications, the internal buffer design is optimized by implementing a priority memory bus controller to a single port memory. And the priority memory bus controller is also designed to minimize the number of synthesized logic gates. To implement the synchronization function of the narrowband TDMA relay communication, the number of gates has been reduced by dividing the frame synchronization circuits and the network slot synchronization circuits. By using these methods, the number of gates are used about 37%(34,000 gates) on Xilinx FPGA XC6SLX9 which has 90,000 gates. For the 1024-bit frame size with a 32-bit synchronization word, the communication reception rate is 96.4%. The measured maximum transmission delay of the designed baseband modem is 230.4 msec for the 14-hop relay communication.

• 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.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.3-10
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• 2012

The visible light communication takes advantages of LED and PD for communication and is considered as a next generation wireless communication technology. It can support variety indoor applications. Especially, Visible LAN service has drawn much attention due to high data rate and no interference with existing WPAN system as well as high efficiency in illumination. However, existing MAC protocol occurs a high communication delay due to uplink collision and backoff time. In this paper, to reduce packet delay, we propose an enhanced MAC protocol based on FDD where the time difference between uplink frame and downlink frame transmission is utilized. Through computer simulations, we verified that the proposed MAC protocol outperforms the existing MAC protocol in terms of average packet delay.

• Journal of Korea Multimedia Society
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• v.19 no.7
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• pp.1166-1178
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• 2016

In Internet of Things (IoT) environments, billions of interconnected devices and multimedia sensors generate a huge amount of multimedia traffic. Since the environment are in general deployed as a server-centric architecture wireless sensor networks could be bottlenecks between IoT gateways and IoT devices. The bottleneck causes high power consumption of the device and triggers very heavy network overload by transmission of sensing data. The deterioration could decrease the quality of multimedia streaming service due to delay, loss, and waste of device power. Thus, in this paper, we propose a context-based adaptive multimedia streaming scheme to support enhanced QoS and low power consumption in IoT environments. The goal of the scheme is to increase quality score per voltage of the streaming service, given an adaptation algorithm with context that are classified network and hardware such as throughput, RTT, and CPU usage. From the both context, the quality score per voltage is used in the comparison of a only network context-based adaptive multimedia streaming scheme, a fixed multimedia streaming and our scheme. As a result, we achieves a high improvement that means the quality score per voltage is increased up to about 4, especially in case of resolution change.

• Journal of Advanced Navigation Technology
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• v.14 no.2
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• pp.213-219
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• 2010

Recently, a multi-core system is studied for single terminal's operations on various service networks for mobile systems. Therefore, it is expected that mobile systems capable of supporting WCDMA, MC-CDMA, CDMA and WiBro would be developed. Mobile systems for supporting various service networks is able to be implemented on a single chipset via SoC(System one Chip) technology, thus a noble modem design proper for SoC technology is necessary. For high speed data transmission of 4G mobile communication services, OFDM scheme has to be applied. But, an OFDM signal consists of a number of independently modulated subcarriers, and superposition of these subcarriers cause a problem that can give a large PAPR. In this paper, a noble modem design for 4G mobile communication services and PAPR reduction method for solving the PAPR problem are proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.713-716
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• 2007

This paper suggests One-time Password key exchange authentication technique for a strong authentication based on Ad-hoc Networks and through identify wireless environment security vulnerabilities, analyzes current authentication techniques. The suggested authentication technique consists of 3 steps: Routing, Registration, and Running. The Routing step sets a safe route using AODV protocol. The Registration and Running step apply the One-time password S/key and the DH-EKE based on the password, for source node authentication. In setting the Session key for safe packet transmission and data encryption, the suggested authentication technique encrypts message as H(pwd) verifiers, performs key exchange and utilizes One time password for the password possession verification and the efficiency enhancement. EKE sets end to end session key using the DH-EKE in which it expounds the identifier to hash function with the modula exponent. A safe session key exchange is possible through encryption of the H(pwd) verifier.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.11-12
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• 2012

In this paper, efficient visible light communication technology LED (Light Emitting Diode) lighting through the existing infrared sensor used for performance analysis of transmitting and receiving is possible. LED utilizes lighting by changing light into electricity. Lighting features while maintaining the basic principles of flashing LED and PD (Photo Diode) to send and receive communications from LED lighting communication convergence principle be realized simultaneously enabling. Multiple IT applications under the basic structure of LED technology development, and the current was encountered in real life. LED lighting anywhere with wireless communication technology that can, in order to ~ 1m above the initial value by taking advantage of the system H/W and infrared sensors(PD) are widely used in the entire system that can improve the speed of visible light data transmission system is finished. LED module that is used to communicate whether the performance analysis, For forecasting and communication distance on the LED and infrared sensor configuration of the implementation of the research is to study about the possibility of application methods and indicates.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.917-926
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• 2005

In this paper, we propose a transport layer mobility support protocol for multimedia streaming services in mobile/wireless environments by extending PR-SCTP to support mobility. We named the proposed scheme to be uPR-mSCTP. The rules related to provide unordered and unreliable data transfer, as well as an approach to minimize handover latency we proposed. Through the simulation results, it is shown that, since uPR-mSCTP reduces transmission rates during handover, not only it reduces the waste of network resources, but it also has the packet loss rate similar to FMIPv6, which is a lot smaller than UDP over MIPv6 or HMIPv6 It also incurs smaller control packet overhead compared to the network layer mobility support approaches.