• Title/Summary/Keyword: operating algorithm

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A Design and Implementation of the Real-Time MPEG-1 Audio Encoder (실시간 MPEG-1 오디오 인코더의 설계 및 구현)

  • 전기용;이동호;조성호
    • Journal of Broadcast Engineering
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    • v.2 no.1
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    • pp.8-15
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    • 1997
  • In this paper, a real-time operating Motion Picture Experts Group-1 (MPEG-1) audio encoder system is implemented using a TMS320C31 Digital Signal Processor (DSP) chip. The basic operation of the MPEG-1 audio encoder algorithm based on audio layer-2 and psychoacoustic model-1 is first verified by C-language. It is then realized using the Texas Instruments (Tl) assembly in order to reduce the overall execution time. Finally, the actual BSP circuit board for the encoder system is designed and implemented. In the system, the side-modules such as the analog-to-digital converter (ADC) control, the input/output (I/O) control, the bit-stream transmission from the DSP board to the PC and so on, are utilized with a field programmable gate array (FPGA) using very high speed hardware description language (VHDL) codes. The complete encoder system is able to process the stereo audio signal in real-time at the sampling frequency 48 kHz, and produces the encoded bit-stream with the bit-rate 192 kbps. The real-time operation capability of the encoder system and the good quality of the decoded sound are also confirmed using various types of actual stereo audio signals.

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Auto Tuning of Position Controller for Proportional Flow Control Solenoid Valve (비례유량제어밸브 위치제어기 자동조정)

  • Jung, Gyu-Hong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.7
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    • pp.797-803
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    • 2012
  • Proportional solenoid valves are a modulating type that can control the displacement of valves continuously by means of electromagnetic forces proportional to the solenoid coil current. Because the solenoid-type modulating valves have the advantages of fast response and compact design over air-operated or motor-operated valves, they have been gaining acceptance in chemical and power plants to control the flow of fluids such as water, steam, and gas. This paper deals with the auto tuning of the position controller that can provide the proportional and integral gain automatically based on the dynamic system identification. The process characteristics of the solenoid valve are estimated with critical gain and critical period at a stability limit based on implemented relay feedback, and the controller parameters are determined by the classical Ziegler-Nichols design method. The auto-tuning algorithm was verified with experiments, and the effects of the operating point at which the relay control is activated as well as the relay amplitude were investigated.

Experimental and Theoretical Consideration for Flow Rate, Pressure Drop, and Permeate Flow in a Hollow Fiber Membrane (중공사 막을 따라 흐르는 순수한 물의 유량, 압력손실, 투과수에 대한 실험과 이론적 고찰)

  • Lee, Jung-Muk;Lee, Bomsock
    • Membrane Journal
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    • v.22 no.6
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    • pp.470-480
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    • 2012
  • In this study, for a linear tubular membrane with constant diameter the mass balance considering permeate velocity of the each unit length was established. On this basis, mathematical modelling of flows in a pipe was solved using nonlinear second order differential equations as well as steady-state equation. Since this equation is nonlinear, Gauss-Seidel method or another iteration method were used to solve the differential equations. Simulation algorithm for numerical solutions was presented. Also since the permeate flow is varied as operating condition, the solution of equations at each conditions using numerical integrations such as Simpson's rules was used. In order to analyze and compare simulation results, we have performed experiments using a hollow fiber membrane with almost identical tubular membrane. Comparison of theoretical and experimental results, pressure drop, flow rate, and permeate flow in a hollow fiber membrane, were illustrated.

A Study on the Effectiveness of JPEG2000 for Medical Image Compression (의료영상 압축을 위한 JPEG2000의 효율성 연구)

  • Jung, Jae-Ho;Shin, Jin-Ho;Son, Gi-Gyeong;Kang, Hee-Doo
    • Korean Journal of Digital Imaging in Medicine
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    • v.6 no.1
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    • pp.31-40
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    • 2003
  • Purpose : In a PACS(Picture Archiving Communications System) environment, which is a very important component in a digital medical environment, the compression of digital medical images is a necessary and effective feature. In a current system where JPEG is applied to the compression of medical images, this study is to examine effectiveness and suitability when the JPEG2000, a more advanced compression algorithm for still images, is applied to the compression of medical images. In this thesis, we attempt to address the compressibility for effective clinical usage when compressing medical images, applying the objectivization of clinical evaluation as a function of compressibility. In the experiment al method, the compression was applied at a fixed rate using JPEG2000, and the n the result was compared with compressed images by JPEG. Method : For the performance evaluation, we choose SNR(Signal to Noise Ratio) measurement of an objective evaluation of definition and analyze a subjective evaluation by the ROC(Receiver Operating Characteristic) method. The results of the experiment showed that in the case of JPEG2000 there is hardly any distortion of images, even at high compression ratio(100:1), while regarding noise, the SNR remains around about 40dB, which is also relatively high. Before reading by reference to evaluative materials concerning objective compressed images, it is impossible to apply high compression to images : however, after reading, this can be applied to images that have already existed for some time.

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Speech Quality Estimation Algorithm using a Harmonic Modeling of Reverberant Signals (반향 음성 신호의 하모닉 모델링을 이용한 음질 예측 알고리즘)

  • Yang, Jae-Mo;Kang, Hong-Goo
    • Journal of Broadcast Engineering
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    • v.18 no.6
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    • pp.919-926
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    • 2013
  • The acoustic signal from a distance sound source in an enclosed space often produces reverberant sound that varies depending on room impulse response. The estimation of the level of reverberation or the quality of the observed signal is important because it provides valuable information on the condition of system operating environment. It is also useful for designing a dereverberation system. This paper proposes a speech quality estimation method based on the harmonicity of received signal, a unique characteristic of voiced speech. At first, we show that the harmonic signal modeling to a reverberant signal is reasonable. Then, the ratio between the harmonically modeled signal and the estimated non-harmonic signal is used as a measure of standard room acoustical parameter, which is related to speech clarity. Experimental results show that the proposed method successfully estimates speech quality when the reverberation time varies from 0.2s to 1.0s. Finally, we confirm the superiority of the proposed method in both background noise and reverberant environments.

Design of Radix-4 FFT Processor Using Twice Perfect Shuffle (이중 완전 Shuffle을 이용한 Radix-4 FFT 프로세서의 설계)

  • Hwang, Myoung-Ha;Hwang, Ho-Jung
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.2
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    • pp.144-150
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    • 1990
  • This paper describes radix-4 Fast Fourier Transform (FFT) Processor designed with the new twice perfect shuffle developed from a perfect shuffle used in radix-2 FFT algorithm. The FFT Processor consists of a butterfly arithmetic circuit, address generators for input, output and coefficient, input and output registers and controller. Also, it requires the external ROM for storage of coefficient and RAM for input and output. The butterfly circuit includes 12 bit-serial ($16{\times}8$) multipliers, adders, subtractors and delay shift registers. Operating on 25 MHz two phase clock, this processor can compute 256 point FFT in 6168 clocks, i.e. 247 us and provides flexibility by allowing the user to select any size among 4,16,64,and256points. Being fabricated with 2-um double metal CMOS process, it includes about 28000 transistors and 55 pads in $8.0{\times}8.2mm^2$area.

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Simulator for Performance Analysis of Wireless Network based on Microsoft Windows Operating Systems (MS 윈도우즈 운영체제 기반의 무선 네트워크 성능 분석 시뮬레이터의 설계 및 구현)

  • Choi, Kwan-Deok;Jang, Ho
    • Journal of the Korea Society of Computer and Information
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    • v.15 no.2
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    • pp.155-162
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    • 2010
  • To ensure accurate measurements of wireless network performance, it should be collected real-time data which are transmitted between a large number of nodes in the actual network environment. Therefore, it is necessary to develop simulation tool for finding optimal network system design method such as media access control, routing technique, ad-hoc algorithm of node deployment while overcoming spatial and temporal constraints. Our research attempts to provide an improved architecture and design method of simulation tool for wireless network is an application of multi-threading technique in these issues. We finally show that usability of the proposed simulator by comparing results derived from same test environment in the wireless LAN model of our simulator and widely used network simulation package, NS-2.

Control of Pressure and Thrust for a Variable Thrust Solid Propulsion System Using Linearization (선형화 기법을 이용한 가변추력 고체추진 기관의 압력 및 추력 제어)

  • Kim, Young-Seok;Cha, Ji-Hyeong;Ko, Sang-Ho;Kim, Dae-Seung
    • Journal of the Korean Society of Propulsion Engineers
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    • v.15 no.4
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    • pp.18-25
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    • 2011
  • Solid propulsion systems have simple structures compared to other propulsion systems and are suitable for long-term storage. However the systems generally have limits on control of thrust levels. In this paper we suggest control algorithms for combustion chamber pressure of variable thrust solid propulsion systems using special nozzles such as pintle valve. For the pressure control within the chamber, we use a simple pressure change model by considering only mass conservation within the combustion chamber, design a classical algorithm and also a nonlinear controller using the feedback linearization technique. Also we derive the equation of the thrust for an under-expanded one-dimensional nozzle and then design a proportional-intergral controller after linearizing the thrust model for an operating point. Finally, we demonstrate the performance of the controller through a numerical simulation.

The Control Method of Rehabilitation Assistance Mobile Robot Using Force-Reflection Joystick (힘 반향 조이스틱을 이용한 재활보조용 이동 로보트의 제어 기법)

  • 이응혁;권오상;김병수;민홍기;장원석;홍승홍
    • Journal of Biomedical Engineering Research
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    • v.18 no.4
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    • pp.447-456
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    • 1997
  • When the disabled is operating a rehabilitation assisting system with a joystick by himself, unlike in the case of a normal person, tremor with joystick control or instant miscontrol can often occur. If these misoperations should be directly relayed to the system, shaking or malfunction of the mobile rehabilitation assisting system might be the result. The safety of the disabled is of prime concern. To solve this problem, that is, to prevent the miscontrol of the disabled operator and avoid crashes into his or her surroundings, we propose the force-reflection locomotion algorithm with the joystick. This method uses ultrasonic sensors to measure the distance between the object and mobile robot. Based on the reception of sensory data, the necessary torque is applied via the joystick to the attatched motor. To confirm the effectiveness of the proposed method, the subjects on the reflected force by the dynamic characteristics of the joystick and the reflected force by the distance information are tested Even though there are some differences in human dexterity, we confirmed the fact that the information from the obstacles was relayed to the operator via the joystick and resulted in an improved operational performance and safety level with regard to those obstacles.

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Time Slot Exchange Protocol in a Reservation Based MAC for MANET

  • Koirala, Mamata;Ji, Qi;Choi, Jae-Ho
    • Journal of the Institute of Convergence Signal Processing
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    • v.10 no.3
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    • pp.181-185
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    • 2009
  • Recently, much attention to a self-organizing mobile ad-hoc network is escalating along with progressive deployment of wireless networks in our everyday life. Being readily deployable, the MANET (mobile ad hoc network) can find its applications to emergency medical service, customized calling service, group-based communications, and military purposes. In this paper we investigate a time slot exchange problem found in the time slot based MAC, that is designed for IEEE 802.11b interfaces composing a MANET. The paper provides a method to maintain the quality of voice call by providing a new time slot when the channel assigned for that time slot gets noisy with interferences induced from other nodes, which belong to the same and/or other subgroups. In order to assess the performance of the proposed algorithm, a set of simulations using the OPNET modeler has been performed assuming that the IEEE 802.11b interfaces are operating under a modified MAC, which is a time slot based reservation MAC implemented in the PCF part of the superframe. In a real-time voice call service over a MANET of a size 500 ${\times}$ 500 meter squares with the number of nodes up to 100, the simulation results are collected and analyzed with respect to the packet loss rate and packet delay. The results show us that the proposed time slot exchange protocol improves the quality of voice call over that of plain DCF.

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