• Proceedings of the IEEK Conference
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.121-122
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• 2006

In this paper, a zigbee system is based on IEEE 802.15.4 is a technology. It is a wireless communication and Ubiquitous Sensor Network which we have been concern about. It attempts to provide a low data rate, low power, low cost and short sensor wireless networking on the device-level communication. These devices are likely to operate in offices and factories. In this paper, we introduce some receiver schemes and show a BER performance.

• Journal of Navigation and Port Research
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• 제38권2호
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• pp.121-126
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• 2014

This paper suggests a new algorithm to provide low-cost GPS modules with DGPS service, which corrects the error vector in the already-calculated position by projecting range corrections to position domain using the observation matrix calculated from the satellite elevation and azimuth angle in the NMEA GPGSV data. The algorithm reduced the horizontal and vertical RMS error of U-blox LEA-5H module from 1.8m/5.8m to 1.0m/1.4m during the daytime. The algorithm has advantage in improving the performance of low-cost module to that of DGPS receiver by a software update without any correction in hardware, therefore it is expected to contribute to the vitalization of the future high-precision position service infrastructure by reducing the costumer cost and vender risk.

• International Journal of Aeronautical and Space Sciences
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• 제17권2호
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• pp.222-231
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• 2016

This paper proposes a new method achieving computationally efficient attitude reference system for low cost strapdown sensors and microprocessor platform. The main idea in this method is to define and compare velocity differential vectors, geometrically computed from INS and GPS data with different update rate, for generating attitude error measurements which is further used for filter construction. A quaternion based Kalman filter configuration is applied for the attitude estimation with the adapted measurement model of differential vector comparison. Linearized model for Extended Kalman Filter and low pass filtered characteristics of measurement greatly extend the affordability of the proposed algorithm to the field of simple low cost embedded systems. For performance verification, experiment are done employing a practical low cost MEMS IMU and GPS receiver specification. Performance comparison with a high grade navigation system demonstrated good estimation result.

• ETRI Journal
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• 제38권5호
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• pp.981-987
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• 2016

We present a cost-effective dual polarization quadrature phase-shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two $90^{\circ}$ optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of $2%-{\Delta}$. Two four-channel spot-size converter integrated waveguide-photodetector (PD) arrays are bonded on PD carriers for transverse-electric/transverse-magnetic polarization, and butt-coupled to a polished facet of the PLC using a simple chip-to-chip bonding method. Instead of a ceramic sub-mount, a low-cost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans-impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3-dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of $8.3{\times}10^{-11}$ is achieved at a 112-Gbps back-to-back transmission with off-line digital signal processing.

• Journal of Institute of Control, Robotics and Systems
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• 제15권11호
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• pp.1102-1107
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• 2009

An ultrasonic sensor has been widely used as a range sensor for its low cost and capability of detecting some obstacles, such as glasses and black surfaces, which are not well detected by a laser scanner and an IR sensor. Although low-cost sensors are preferred for practical service robots, they suffer from the inaccurate and insufficient range information. This paper proposes a novel approach to obstacle avoidance using low-cost anisotropic ultrasonic sensors with wide beam angle. In this paper, obstacles can be detected by the proposed sensor configuration which consists of one transmitter and three receivers. Because even wide obstacles are represented by a point, which corresponds to the intersection of range data from each receiver of the anisotropic sensor, a robot cannot avoid wide obstacles successfully. This paper exploits the probabilistic mapping technique to avoid collision with various types of obstacles. The experimental results show that the proposed method can robustly avoid obstacles in most indoor environments.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.191-196
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• 2005

A low-cost, high-performance 40 Gb/s clock recovery module using a phase-locked loop(PLL) for a 40 Gb/s optical receiver has been designed and implemented. It consists of a clock recovery circuit, a RF mixer and frequency discriminator for phase/frequency detection, a DR-VCO, a phase shifter, and a hold circuit. The recovered 40 GHz clock is synchronized with a stable 10 GHz DR-VCO. The clock stability and jitter characteristics of the implemented PLL-based clock recovery module has shown to significantly improve the performance of the conventional open-loop type clock recovery module with DR filter. The measured peak-to-peak RMS jitter is about 230 fs. When input signal is dropped, the 40 GHz clock is generated continuously by hold circuit. The implemented clock recovery module can be used as a low-cost and high-performance receiver module for 40 Gb/s commercial optical network.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제17권9호
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• pp.2139-2144
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• 2013

This paper has analyzed the possibility about implementation of the low-cost, high-efficiency tracking antenna using flat panel antenna. Tracking antenna is consisted of four flat-antenna, comparators, tracking receiver, controller. We analyzed input signal of antenna array about the magnitude and phase of radio wave. In addition, We suggested the available tracking range through the analysis of output signal. We have minimized the error rate that happened on two path through design two path of the azimuth and elevation. Analysis results has a tracking range of ${\pm}3$ degrees, it is possible to implement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.443-447
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• 1996

The meeds of vehicle navigation system are increassing and the accurate determination of position is still of promary improtance. GPS (Global Positioning System)receiver and low cost dead reckoning sensors have been used for vehicle position location. The integartion of these can improve the system performance to cope with accumulating errors and multipath problem in urban area. However, the implementation of integrated system of two sensors is net easy, for their real data ave noises that are not apt to be modeled. This paper discusses how to combine a GPS receiver and dead reckoning sensors. The characteriatics of sensors and their data are investigated, and the system for field test is manufactured. The test results of a selected typical route are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제25권5호
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• pp.39-44
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• 2011

Automatic fire alarm system is set up to automatically detect fire on buildings. Because of economic reasons, P-type receiver and a conventional type fire detector is normally used for automatic fire alarm system in Korea. Because early detection of fire is regarded as important, the need of finding technique of fire location increases. This paper is studied a method to improve a reliability and add a function of fire location detection on a conventional type fire detector and P-type receiver. Fire location is detected by a method that controller attached on the receiver and the detector is read with a time lag. A reliability of fire detection alarm system is improved with a method that false fire alarm is able to decrease using two different principle detector together. This paper is studied for basic data of improvement of low-cost addressable automatic fire alarm system.

• Journal of the Korea Institute of Military Science and Technology
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• 제9권2호
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• pp.96-102
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• 2006

In this paper, the design, construction and basic characteristics of an electronically adaptive array antenna for the GPS receiver is described. The susceptibility of the GPS signals to the interference is of concern to the GPS user community. Because of the low received power of the GPS signals, outages can easily occur due to the unintentional interference and the easily obtainable low cost GPS jammer denying access to the GPS signals. We propose a technique of the adaptive array antenna that detects the GPS interference sources and controls the null beam pattern only toward the jamming sources to acquire GPS navigation data after acquisition and tracking of the GPS signals.