• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.6
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• pp.18-26
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• 1999

This paper presents the architecture and design of a DSSS MODEM ASIC chip for wireless local area networks (WLAN). The implemented MODEM chip supports the DSSS physical layer specifications of the IEEE 802.11. The chip consits of a transmitter and a receiver which contain a CRC encoder/decoder, a differential encoder/decoder, a frequency offset compensator and a timing recovery circuit. The chip supports various data rates, i.e., 4,2 and 1Mbps and provides both DBPSK and DQPSK for data modulation. We have performed logic synthesis using the $SAMSUNG^{TM}$ $0.6{\mu}m$ gate array library and the implemented chip consists of 53,355 gates. The MODEM chip operates at 44MHz, the package type is 100-pin QFP and the power consumption is 1.2watt at 44MHz. The implemented MODEM architecture shows lower BER compared with the Harris HSP3824.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.46-54
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• 2006

In this paper, we propose a digital transceiver that can overcome the problems which current analog transceivers have. For the proposed transceiver, we assumed a frequency resource that consists of discrete and narrow channels. We also assumed that person-to-group, group-to-group, as well as person-to-person, voice and data communications with moderate security should be devisedand the data rate is 1 Mbps with simultaneous voice and data. Frequency hewing spread spectrum (FH-SS) and differential 8-PSK (D8PSK) were adopted for security reasons and bandwidth constraints, and for the reduction of implementation complexity, respectively. For the carrier and the symbol timing recovery, the structure of the preamble was proposed based on the IEEE 802.11 FHSS frame format to improve detection probability. The computer simulation results and power budget analysis implies that the proposed system can be usedin simple wireless communications in place of such as analog walkie-talkies.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.85-91
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• 2007

Satellite Digital Multimedia Broadcasting (S-DMB) is the digital convergence service of broadcasting and communication for mobility and portability. Broadcasting service of S-DMB can be taken by the mobile phone or vehicle terminals anytime and anywhere. S-DMB system is currently providing 11 video channels and 26 audio channels. As the demand of multimedia service is recently increasing, S-DMB system needs high quality and new contents service. Therefore we need to make efficient S-DMB with more channel ability and high transmission quality. In this paper, we propose new S-DMB system that can be applied to powerful channel coding scheme and hierarchical 8-PSK(8-Phase Shift Keying) modulation with Backwards Compatibility modes that simultaneously can support both current and new system. And we analyze the performance of current S-DMB system and verify a possibility of advanced S-DMB through computer simulation.

• Convergence Security Journal
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• v.15 no.2
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• pp.11-17
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• 2015

According to NIA (National Information Society Agency) report, digital divide is a vicious circle which makes quality interval of human's life between people who have information and relatively not. Especially in a smart phone society, there is a big problem between disabled people and normal people. This paper suggests a braille keyboard system for the blind to solve these problems. It is designed for portable use, convenience and quick text typing based on bluetooth communication technique. In text input test, all texts (Korean, English, number) were accurately expressed and typing speed was about 22 [c/m](characters per a minute). Especially, we design text2voice function to provide more accurate key input system. Popular applications such as call, alarm, message, kakao talk, internet, music, were performed without carring problems using the proposed braille keyboard system. The proposed technique is thought to contribute to eliminating the digital divide through the expansion of smartphone users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3B
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• pp.314-324
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• 2004

Recently, high-speed internet subscribers have grown continuously, and reached up to 10 millions. But existing network management that is responsible only for user access is confronted with many difficulties, since user access network(xDSL, Cable, B-WILL, and so on) has diversified and value added wired/wireless contents service has developed. In this paper propose the Agent based Inter Networking platform as object-oriented hierarchical system that can provide various service such as access QoS(Quality of Service), customized application service and security service according to user on demand. This system has divided into two parts(user agent and agent management system ＆ local and central management systems). Management system periodically receive status information such as bandwidth, download speed, delay, current service, and so on, and process them, then build a policy based on processed information. According to personal user profile that is generated by this policy, the customized service can be provided for users. And This system adopt the object-oriented modeling in case that system migration and integration, and implement a system that is robust and stable for security through hierarchical server system.

• Convergence Security Journal
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• v.16 no.5
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• pp.3-9
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• 2016

The wireless sensor networks have become an economically viable monitoring solution for a wide variety of civilian and military applications. The main challenge in wireless sensor networks is the secure transmission of information through the network, which ensures that the network is secure, energy-efficient and able to identify and prevent intrusions in a hostile or unattended environment. In that correspondence, this paper proposes a distributed clustering process that integrates the necessary measures for secure wireless sensors to ensure integrity, authenticity and confidentiality of the aggregated data. We use the notion of pre-distribution of symmetric and asymmetric keys for a secured key management scheme, and then describe the detailed scheme which each sensor node within its cluster makes use of the pre-distribution of cryptographic parameters before deployment. Finally, we present simulation results for the proposed scheme in wireless sensor network.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.7
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• pp.46-56
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• 2002

In this paper, we describe a hardware-software co-verification methodology and environment in developing a mobile station modem chip for cdma2000 1x which is one of the 3rd generation mobile communication standards. By constructing an efficient co-verification environment for a register-transfer-level hardware model and a physical-layer software model combining a channel link simulator and a versatile test-bench, we can drastically reduce both time and cost for developing a complex three-million-gate class system integrated circuit.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.10
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• pp.941-948
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• 2016

In this paper, we efficiently simulated for collecting the data from the fixed sensor and mobile sensor of patients using the LEACH-Mobile method. The LEACH-Mobile method is the protocol to increase the mobility by adding the mobile node to the existed LEACH(:Low Energy Adaptive Clustering Hierarchy) protocol. It improves the mobility of The LEACH-Mobile in the LEACH, however it consumes more energy than the existed LEACH. There is reason why we use the LEACH-Mobile that the monitoring system is generally done by the CCTV and an periodic checkup by nurses. However the number of nurse is a few in the most of hospital. It can happen the accidents of the patients in out of the CCTV when the nurse can not see the monitoring system in the hospital. Therefore it is simulated to continuously gather the data of the position and sensors in the five situation of moving the patients in the hospital, it gets the result that the management of the mobile patients is more efficient.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.38-45
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• 2016

For higher efficiency and reliability of railroad trains with many electronic sensors and actuators, a distributed control system with which electronic components communicate with each other in a distributed manner via a data network is considered. This paper considers Ethernet-based Train Communication Network (TCN) for this purpose and proposes a methodology to optimize the topology in terms of transmission latency and reliability, each of which is modeled as the number of traversing backbone nodes and the number of cables between vehicles, respectively. An objective function is derived accordingly and a closed-form optimum is obtained by relaxing the integer constraint of the number of vehicles for a unit network. Then, the final integer optimum is searched around it. Through numerical evaluation, the validity of the proposed methodology and the characteristics of the resulting solutions are shown.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.61-67
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• 2008

Proxy MIPv6 (PMIPv6) is that network-based mobility management protocol that network supports mobile node's mobility on behalf of the MN. In PMIPv6, when two MNs located within the same PMIPv6 domain want to communicate each other, sub-optimal path is established between the two MN. Route optimization method for PMIPv6 is proposed to resolve the problem. However, the method still suffer from the performance degradation due to out-of-sequence packet problem. In this paper, we propose the route optimization mechanism in PMIPv6 based on Flush message to resolve the out-of-sequence packet problem. The proposed mechanism is evaluated by performing simulations, and the simulation results show that the proposed one gives better performance.