• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.344-346
• /
• 2018

Air pollution has become a social issue. Particularly, interest in fine dust is increasing. Various kinds of sensors are being used to measure fine dust. The most commonly used infrared detection dust sensors operate by sensing the diffraction of light through an infrared receiver and sensing the light reflected by the dust in the air. However, this method has a drawback in which accurate data analysis is difficult due to deviation caused by the noise during measurement. In order to overcome such drawbacks, in this thesis, a low pass filter algorithm of FIR(Finite Impulse Response) filter was designed and implemented.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37B no.11
• /
• pp.1004-1013
• /
• 2012

The legacy voice broadcast systems are used to broadcast the voice over an entire space or a specific zone. these broadcast systems generate unnecessary noise and waste of resources. In this paper, we propose a ubiquitous voice message broadcast system called uPaging, by combining the technique of location-awareness and the voice message delivery service in ubiquitous sensor network environment. In uPaging system, the wire/wireless hybrid network is used to implement the network system. Also, in order to actualize the location-awareness service, we use the Bidirectional Location ID-Exchange protocol was suggested by our previous research. the uPaging system can deliver the voice to a selected user or the location in which the user is present by this location awareness.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.9
• /
• pp.519-527
• /
• 2014

Adaptive arrays can minimize contributions from interferences incident onto an sensor array while preserving a signal the direction vector of which corresponds to the array steering vector to within a scalar factor. If there exist errors in the steering vector, severe performance degradation can be caused since the desired signal is misunderstood as an interference by the array. This paper presents an adaptive beamforming method which is robust against steering vector errors, exploiting a range of the desired signal direction. In the presented method, an correlation matrix of array response vectors is obtained through integration over the direction range and a minimization problem is formulated using some eigenvectors of the correlation matrix such that a more accurate steering vector than initially given one can be found. The minimization problem is transformed into a relaxed SDP (semidefinite program) problem, which can be effectively solved since it is a sort of convex optimization. Simulation results show that the proposed method outperforms existing ones such as ORM (outside-range-based method) and USM (uncertainty-based method).

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.11
• /
• pp.937-946
• /
• 2014

This paper presents system identification of a single tilt wing UAV. A Modified Equation Error Method(MEEM) and Extended Kalman Filter(EKF) are used for the identification of a single tilt wing UAV system in frequency-domain and time-domain, respectively. Simulated flight data is obtained from CNUX-3's vertical mode linear simulation with realistic sensor noise. System identification performance is analyzed with respect to a variety of design parameters of the MEEM. Also, High accuracy Fourier Transform(HFT) is applied to enhance the performance of MEEM. The results of the MEEM is compared with those of the EKF. Design parameters of the MEEM and initial conditions of the EKF are decided from optimization.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1417-1422
• /
• 2005

Among the sensors mainly used for displacement measurement, there are a linear CCD(Charge Coupled Device) and a PSD(Position Sensitive Detector) as a non-contact type. Their structures are different very much, which means that the signal processing of both sensors should be applied in the different ways. Most of the displacement measurement systems to get the 3-D shape profile of an object using a linear CCD are a computer-based system. It means that all of algorithms and mathematical operations are performed through a computer program to measure the displacement. However, in this paper, the developed system has microprocessor and other digital components that make the system measure the displacement of an object without a computer. The thing different from the previous system is that AVR microprocessor and FPGA(Field Programmable Gate Array) technology, and a comparator is used to play the role of an A/D(Analog to Digital) converter. Furthermore, an ATC(Automatic Threshold Control) algorithm is applied to find the highest pixel data that has the real displacement information. According to the size of the light circle incident on the surface of the CCD, the threshold value to remove the noise and useless data is changed by the operation of AVR microprocessor. The total system consists of FPGA, AVR microprocessor, and the comparator. The developed system has the improvement and shows the better performance than the system not using the ATC algorithm for displacement measurement.

• Journal of IKEEE
• /
• v.18 no.1
• /
• pp.119-127
• /
• 2014

This paper presents a CMOS readout circuit for MEMS(Micro Electro Mechanical System) acceleration sensors. It consists of a MEMS accelerometer, a capacitance to voltage converter(CVC) and a second-order switched-capacitor ${\Sigma}{\Delta}$ modulator. Correlated-double-sampling(CDS) and chopper-stabilization(CHS) techniques are used in the CVC and ${\Sigma}{\Delta}$ modulator to reduce the low-frequency noise and DC offset. The sensitivity of the designed CVC is 150mV/g and its non-linearity is 0.15%. The duty cycle of the designed ${\Sigma}{\Delta}$ modulator output increases about 10% when the input voltage amplitude increases by 100mV, and the modulator's non-linearity is 0.45%. The total sensitivity is 150mV/g and the power consumption is 5.6mW. The proposed circuit is designed in a 0.35um CMOS process with a supply voltage of 3.3V and a operating frequency of 2MHz. The size of the designed chip including PADs is $0.96mm{\times}0.85mm$.

• Journal of the Korea Convergence Society
• /
• v.11 no.11
• /
• pp.195-201
• /
• 2020

This paper implemented quadcopter-type drone system and proposed the heuristic method for obtaining the optimum gain coefficients in order to minimize the settling time. Control system for quadcopter posture stabilization reads the posture data from accelerator and gyro sensor, revises the original posture data using Mahony filter, and drives 4 DC motors using PID controller. The first step of the proposed method is to obtain the gain coefficients using the Ziegler-Nichols method, and then determine the optimum gain coefficients using the heuristic method at the next 3 steps. The experimental result shows that the maximum overshoot decreases from 44.3 to 29.8 degrees and the settling time decreases from 2.6 to 1.7 seconds compared to the Ziegler-Nichols method. Therefore, we proved that the proposed method works well in quadcopter flight system with high motor noise while reducing trial and error to obtain the optimal PID gain coefficients.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.6
• /
• pp.87-93
• /
• 2019

We discuss the design of a radiometer using a millimeterwave(Ka-band) seeker. We applied a total power radiometer, thus the radiometer is composed of a IF-drive amp, band-pass filter, detector and an Op-amp additionally. As a radiometer measure a radiated signal of an object which is noise-like, a radiometer is easily affected by the variance of system temperature. To mitigate an adverse effect, we propose a compensation method in a radiometer without brightmess temperature compensation circuits. Through some experiments such like a distinction a target and the background, we have verified that the designed radiometer system has distingushed a car from the ground completely.

• Journal of IKEEE
• /
• v.23 no.4
• /
• pp.1295-1301
• /
• 2019

In this paper, we propose a novel method of denoising human motion using a bidirectional recurrent neural network (BRNN) with an attention mechanism. The corrupted motion captured from a single 3D depth sensor camera is automatically fixed in the well-established smooth motion manifold. Incorporating an attention mechanism into BRNN achieves better optimization results and higher accuracy than other deep learning frameworks because a higher weight value is selectively given to a more important input pose at a specific frame for encoding the input motion. Experimental results show that our approach effectively handles various types of motion and noise, and we believe that our method can sufficiently be used in motion capture applications as a post-processing step after capturing human motion.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.42 no.3
• /
• pp.45-50
• /
• 2005

A UV camera is being used in various application regions such as industry, medical science, military, and environment monitoring. A ROIC(ReadOut IC) is developed and can read the responses from UV photodiode sensors which are made with III-V nitride semiconductors of GaN series haying high resolution and high efficiency. To design FPA(Focal Plane Array) UV $8{\times}8$ ROIC, the photodiode type sensor devices are modeled as the capacitor type ones. The ROIC reads out signals from the detector at)d outputs sequentially pixel signals after amplifying and noise filtering of them. The ROIC is fabricated using the $0.5{\mu}m$ 2Poly 3Metal N-well CMOS process. And then, it and photodiode array are hybrid bonded by gold stud bumping process using ACP(Anisotropic Conductive Paste). After the packaging, UV images appearing on PC verified the operations of the ROIC.