• Proceedings of the KAIS Fall Conference
• /
• 2008.05a
• /
• pp.251-253
• /
• 2008

RFID 태그에 통신 기능이 부가되고 점차 주위 환경을 감지하는 센싱 기능이 부가되면, 능동적으로 정보를 처리하는 지능형 초소형 스마트 센서 네트워크로 발전되어 현재의 고정된 개체 인식 코드 획득 수준에서 다기능 태그에 의한 상황인지 처리 수준으로 진화하여, 개체간 통신 기능을 갖춘 지능형 USN으로 발전할 것으로 전망 된다. ZigBee는 기기간 센서 네트워크를 구성, 단순 제어와 관리를 수행할 수 있는 WPAN의 최적의 기술로 평가 받고 있으며 저 전력, 저가 등의 장점 등으로 시장 성장성이 높은 기술이다. 유/무선 인프라를 확보하고 있는 우리는 ZigBee를 기존, 또는 현재 구축중인 유무선 네트워크와 연결해 다양한 유비쿼터스 서비스를 개발할 수 있는 최적의 테스트베드 환경을 갖추고 있으므로 u-Health의 기반에 꼭 필요한 기술이다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.2
• /
• pp.294-301
• /
• 2013

OFDM technique uses multiple sub-carriers for the data transmission. Therefore, bit error rate increases because of inter-carrier interference caused by nonlinear high power amplifier and carrier frequency offset. Wireless OFDM transmission over multi path fading channels is characterized by small transmission gain in multiple sub-carrier frequency interval. Therefore bit error rate increases because of burst errors. Inter-leaver and convolution error control coding are effective for the reduction of this burst error. Pilot symbol is used for the channel estimation in OFDM systems. However, imperfect channel estimates in this systems degrade the performance. The performance of this convolution coding OFDM systems using inter-leaver, gauged by the bit error rate, is analyzed considering the nonlinear high power amplifier, carrier frequency offset and channel estimation error.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.6
• /
• pp.1321-1326
• /
• 2015

The amount of smart phones has increased exponentially. Due to the periodic release of high-performance smart phones and upgraded operating system, new smart phones become out-dated over 1 or 2 years. In order to solve environmental constraints of these smart phones, virtualization technology using Thin-Client terminal has been developed. However, in the case of Virtual Machine(VM), the applications associated with sensors and a GPS device can not run because they are not included. In this paper, by implementing the device driver for Android running in a virtual machine in the x86-based systems, it is to provide Android virtualization capabilities such as using the latest smart phones in the virtual machine environment. It would like to propose a method that the virtual device driver receives sensors and GPS information from the old Android smart phones(Thin-Client) that actually work and run as if the real device exists.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.4 no.5
• /
• pp.1143-1150
• /
• 2000

A dual-mode multiplier (DMM) that performs single- and double-precision multiplications has been designed using a $0.25-\mum$ 5-metal CMOS technology. An algorithm for efficiently implementing double-precision multiplication with a single-precision multiplier was proposed, which is based on partitioning double-precision multiplication into four single-precision sub-multiplications and computing them with sequential accumulations. When compared with conventional double-precision multipliers, our approach reduces the hardware complexity by about one third resulting in small silicon area and low-power dissipation at the expense of increased latency and throughput cycles. The DMM consists of a $28-b\times28-b$ single-precision multiplier designed using radix-4 Booth receding and redundant binary (RB) arithmetic, an accumulator and a simple control logic for mode selection. It contains about 25,000 transistors on the area of about $0.77\times0.40-m^2$. The HSPICE simulation results show that the DMM core can safely operate with 200-MHZ clock at 2.5-V, and its estimated power dissipation is about 130-㎽ at double-precision mode.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.3
• /
• pp.558-564
• /
• 2016

The network interference gives positive and negative effects to security and QoS simultaneously by disturbing the decoding of receiver and eavesdropper. The transmission of artificial noise enables to indirectly control these contradicting effects. This paper proposed the secrecy enhancement technique via artificial noise with protected zones of transmitter and receiver and investigated its gain by using stochastic geometry. For given arbitrary artificial noise power ratio, we first analyzed connection outage probability and secrecy outage probability for four different scenarios (separated, overlapped, included secrecy protected zones- type A, B) according to distance and size of protected zones of the transmitter and receiver. We then derive the secrecy transmission rate and find the optimal artificial noise power ratio to maximize it. Finally, with numerical examples, we investigate the effects of the system parameters such as size of protected zones of transmitter and receiver on the optimal artificial noise power ratio.

• 전자공학회논문지 IE
• /
• v.43 no.2
• /
• pp.80-86
• /
• 2006

The wireless communication based on LDPC and adaptive spatial-subcarrier coded modulation using MQAM for orthogonal frequency division multiplexing (OFDM) wireless transmission by using instantaneous channel state information and employing multiple antennas at both the transmitter and the receiver. Adaptive coded modulation is a promising idea for bandwidth-efficient transmission on time-varying, narrowband wireless channels. On power limited Additive White Gaussian Noise (AWGN) channels, low density parity check (LDPC) codes are a class of error control codes which have demonstrated impressive error correcting qualities, under some conditions performing even better than turbo codes. The paper demonstrates OFDM with LDPC and adaptive modulation applied to Multiple-Input Multiple-Output (MIMO) system. An optimization algorithm to obtain a bit and power allocation for each subcarrier assuming instantaneous channel knowledge is used. The experimental results are shown the potential of our proposed system.

• Journal of Internet Computing and Services
• /
• v.14 no.4
• /
• pp.13-24
• /
• 2013

IEEE 802.15.4 network and WiFi network are installed to overlap each other and configured to use adjacent frequency bands in which case the communication service required by applications can not be guaranteed because of randomly increased frame transmission delay and frequent frame transmission failures at nodes in IEEE 802.15.4 network. In this paper, transmission delay model at IEEE 802.15.4 nodes and an experimental system to evaluate the interference from WiFi traffic are described, then elements for the evaluation of interference are measured with the analysis of their characteristics. A sequential method of using medium access layer and physical layer elements of IEEE 802.15.4 protocols is proposed to decide interference from WiFi network. With the proposed method, if an evaluation function having frame transmission failures and transmission delay as variables returns a value greater than a threshold, intensive measurements of wireless channel power are carried out subsequently and the final decision of interference is made by the calculated average channel power. Experimental results of the method show that the decision time is reduced with increased frequency of decision in comparison to an other similar method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.607-608
• /
• 2016

Recently using a variety of sensors sensing the virtual(Virtual Sensing) technology that extracts specific data has been applied to IoT service interface. The utilization of such sensors while increasing IoT (Internet of Things) environmental sensor is an essential element. However, used in the IoT to the environment, while the increase in utilization of a specific sensor utilization falling sensors is generated. In this paper, we design unnecessary sensors removal algorithm as a way to solve this problem. Through the utilization of poor power to block the sensor can reduce the power consumption and user sensor control service through the monitoring by blocking the use of the sensor is considered that there can be provided a more effective and convenient.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.396-397
• /
• 2011

This paper has proposed a multi-channel low pass filter (LPF) for LTE-Advanced systems. The proposed LPF is an active-RC 5th chebyshev topology with three cut-off frequencies of 5 MHz, 10 MHz, and 40 MHz. A 3-bit tuning circuit has been adopted to prevent variations of each cut-off frequency from process, voltage, and temperature (PVT). To achieve a high cut-off frequency of 40 MHz, an operational amplifier used in the proposed filter has employed a PMOS cross-connection load with a negative impedance. A proposed filter has been implemented in a $0.13-{\mu}m$ CMOS technology and consumes 20.2 mW with a 1.2V supply voltage.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.7
• /
• pp.949-955
• /
• 2018

Hardware-in-the-loop (HIL) simulation is a technique that can be employed for developing and testing complex real-time embedded systems. HIL simulation provides an effective platform for verifying power management system (PMS) performance of liquefied natural gas carriers, which are high value-added vessels such as offshore plants. However, HIL tests conducted by research institutes, including domestic shipyards, can be protracted. To address the said issue, this study proposes a field programmable gate array (FPGA) based PMS-HIL simulator that comprises a power supply, consumer, control console, and main switchboard. The proposed HIL simulation platform incorporated actual equipment data while conducting load sharing PMS tests. The proposed system was verified through symmetric, asymmetric, and fixed load sharing tests. The proposed system can thus potentially replace the standard factory acceptance tests. Furthermore, the proposed simulator can be helpful in developing additional systems for vessel automation and autonomous operation, including the development of energy management systems.