• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.853-854
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• 2007

센서네트워크는 유비쿼터스 사회에서 기반환경이 될 가장 중요한 기술 중 하나이다. 이러한 센서네트워크를 보다 효율적으로 관리하기 위해서는 IP 망과의 연동이 필수 적인 조건으로 부각되고 있다. 이러한 흐름에 맞춰 IEEE802.15.4 위에 TCP/IP 를 사용하기 위해 IETF 워킹그룹 6LoWPAN 이 만들어졌다. 본 논문에서는 IP 네트워크와 연동하는 센서네트워크(6LoWPAN)에서 센서의 특성에 따라 데이터를 효율적으로 요청하고 수집하는 프로토콜을 제안하였다.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.18-23
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• 2008

This paper describes development of real-time condition monitoring system to observe state of a container crane in a port. To analyze the state of a crane, the strength and the direction of wind are measured with sensors along with the load resulted a crane at the moment. The measured signals are processed by especially developed conditioning board and converted into digital data. Measured data are analyzed to define the state of the crane at an indicator. For transmission of these data to the indicator, we implemented wireless sensor network based on IEEE 802.15.4 MAC(Media Access Control) protocol and Bluetooth network protocol. To extend the networking distance between the indicator and sensor nodes, the shortest path routing algorithm was applied for WSN(Wireless Sensor Network) networks. The indicator sends the state information of the crane to monitoring server through IEEE 802.11 b wireless LAN(Local Area Network). Monitoring server decides whether alarm should be issued or not. The performance of developed WSN and Bluetooth network were evaluated and analyzed in terms of communication delay and throughput.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1068-1075
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• 2004

The WLAN(IEEE 802.l1b) and Bluetooth(IEEE 802.15.1) employed on 2.4㎓ ISM band wireless networks provide complementary services within the same environments. Coexistence between the networks will be impaired, if the mutual packets are uncertainty associated the timing or gaussian distance. This paper analyzes the impact of the mutual interference on the services performance in order to develope a method of coexistence between the WLAN and Bluetooth. The analysis is illustrated by examining the symbol error rate versus signal to noise interference ratio in terms of the carrier frequency of set.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.1
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• pp.35-42
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• 2022

Visible light communication (VLC) is a method of transmitting data through LED blinking and is vulnerable to eavesdropping because the illumination affects the wide range of area. IEEE standard 802.15.7 defines On-Off Keying (OOK), Variable Pulse Position Modulation (VPPM), and Color Shift Keying (CSK) as modulation. In this paper, we propose an encryption method in VPPM for secure communication. The VPPM uses an encoding method called 4B6B where 16 different outputs are represented with 6-bit. This paper extends the number of outputs to 20, to add complexity while not violating the 4B6B generation conditions. Then each entry in the extended 4B6B table is scrambled using vigenère cipher. The probability of decrypting each 6-bit data is $\frac{1}{20}$. Eavesdropper should perform $\sum\limits_{k=1}^{n}20^k$ number of different trials to decrypt the message if the number of keys is n. The proposed method can be applied to OOK of PHY II and CSK of PHY III. We further discuss the secure encoding that can be used in OOK and CSK without performance degradation.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.736-739
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• 2011

IP 기반의 센서 네트워크인 6LoWPAN 은 IEEE 802.15.4 표준에 IPv6 를 적용하기 위해 제안되었다. 현재 IPv6 상에서 노드의 이동성을 지원하기 위한 기술로 MIPv6 와 PMIPv6 가 표준화 되었다. 6LoWPAN 에서 이동성을 지원하기 위해서 PMIPv6 를 적용하는 것이 MIPv6 를 적용하는 것보다 더 효율적이다. PMIPv6 기술의 특징은 기존의 MIPv6 에 비해 노드가 바인딩 메시지를 처리하지 않는 점이다. 따라서 노드의 부하를 줄일 수 있기 때문에 6LoWPAN 에 적합하다. 하지만 6LoWPAN 노드의 하드웨어적인 제약 사항을 고려해 볼 때, 기존의 PMIPv6 를 그대로 적용하기에는 무리가 있다. 그대로 적용한다면 PMIPv6 은 원 홉에 기반하고 있기 때문에 멀티 홉에 기반한 6LoWPAN 에는 적합하지 않다. 또한 기존에 정의되어 있는 RS 나 RA 메시지의 크기로 인해 멀티 홉 경로상의 각 단말에 많은 부하를 줄 수 있다. 본 논문에서는 위의 문제점을 해결하기 위해 6LoWPAN 에 적합한 RS 와 RA 메시지를 제안한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.41-48
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• 2008

The realization of a monitoring system for senior citizens living alone through wireless sensor network. Due to the recent advances in medical science, people live longer than ever before which accelerates the number of senior citizens. The high rate of the old people in population causes some changes in the form of families, which results in the increasing number of old people living by themselves. This also causes a lot of social problems concerning aging population. For example, people found a dead body of 83-year-old, who had lived alone, after he passed away a month before. There is a national monitoring service for the old people of their daily lives, but the application of such system is very limited. Considering this, the current paper focuses on the realization of a monitoring system for senior citizens living alone through wireless sensor network. The system consists of ZigBee sensor network, which is based on standard IEEE 802.15.4. and the system uses Tmote Sky sensor mote made by Moteive, which is installed with TinyOS. The circumstances information data will be saved on DB and a household will be monitored through a Webpage or Mobile.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6C
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• pp.561-570
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• 2009

Ultra-wideband communication systems based on impulse radio have merits that are possible for the high data rate transmission, high resolution ranging are positioning system. Conventionally, in order to accomplish these features, the high-speed ADC (Analog to Digital Convertor) is necessary to apply radio determination system operating in time domain. However, considering low rate - wireless personal area network (LR-WPAN) aims to low-cost hardware implementation, the expensive ADC converting GHz sampling per second is not appropriate. So, this paper introduces a low complex AR (Auto Regressive) model based non-coherent ranging scheme operating in frequency domain with using low-speed ADC utilizing analog Voltage Control Oscillator (VCO) mode for the frequency domain transformation. To verify the superiority of the proposed ranging and location algorithm working in frequency domain, the suggested IEEE 802.15.4a TG channel model is used to exploit affirmative features of the proposed algorithm with conducting the simulation results.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.87-93
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• 2008

This paper describes implementation of the 5.0GHz RF frequency synthesizer with $0.18{\mu}m$ silicon CMOS technology being used as an application of the IEEE802.15.4 USN sensor node transceiver modules. To get good performance of speed and noise, design of the each module like VCO, prescaler, 1/N divider, fractional divider with ${\Sigma}-{\Delta}$ modulator, and common circuits of the PLL has been optimized. Especially to get good performance of speed, power consumption, and wide tuning range, N-P MOS core structure has been used in design of the VCO. The chip area including pads for testing is $1.1*0.7mm^2$, and the chip area only core for IP in SoC is $1.0*0.4mm^2$. Through comparing and analysing of the designed two kind of the frequency synthesizer, we can conclude that if we improve a litter characteristics there is no problem to use their as IPs.

• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.169-176
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• 2006

Since home network system is usually set up based on the built-in system inside home at the time of construction, it has a difficulty in being compatible with new devices after construction. In this paper, we propose DBS(Dynamic Binding System) that can make links effectively among the devices located in inside and outside of home networks. Implementation of the DBS is based on the ZigBee's binding in WPAN(Wireless Personal Area Network). For this research, we constructed the system consisting of home server that contains proxy server and location server, devices inside home in which tinyOS is embedded, and mobile device that is an emulator. The communication inside home is done by IEEE 802.15.4 protocol and the communication between servers and mobile devices outside home is done by TCP/IP protocol. Regardless of device's address format, the DBS facilitates a link among the devices located inside and outside of home networks. And, introducing a new device into home network can be recognized easily by exchanging messages between devices.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.24-30
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• 2007

In this paper, an energy detection-based low power, low complexity IR-UWB receiver in multipath impulse radio channel is presented. The proposed receiver has a simple 1-bit sampler for energy detection. Also, multipath signal received from multipath impulse radio channel is amplified and envelope of the signal is detected. Then, energy detection technique using integrator by summing multipath signals in certain period is adopted to minimize the BER loss by simple energy detection. In particular, in acquisition of a sample signal, SNR is additionally improved using a digital sampler. Symbol decision using several sampled signals is performed and thus the process of symbol synchronization is significantly simplified. Also, it is effectively designed to be compatible with influences of multipath and timing error. In addition, the proposed receiver complexity is reduced using pulse decision window. The performance of the proposed receiver is simulated based on IEEE 802.15.4a channel model and the algorithms are implemented on FPGA.