• 한국정보통신학회논문지
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• 제11권10호
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• pp.1858-1865
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• 2007

본 논문에서는 위성통신용 IP 모뎀부를 설계 및 구현하였다. 위성 IP모뎀을 위성 의 전송 대역폭, 통신 효율성 등을 고려하여 0.2%의 오버헤드, $E_b/N_o=6dB$에서 $BER=10^{-5}$, 8KHz의 주파수 보정, 1536Kbps 데이터율, 140MHz의 IF 주파수를 갖도록 설계하였다. 설계된 시스템은 시뮬레이션을 통하여 검증하고 MPC86x 통신 프로세서, TMS320C6416 DSP, FPGA 등으로 모듈구조로 구현하여 개발시간의 단축과 성능개선이 용이한 장점을 갖고있다. IP 연동 및 다중 처리를 위한 임베디드 OS로 리눅스를 이용하여 모뎀의 각 하드웨어 에 대한 디바이스 드라이버를 설계하였다. 개발된 하드웨어는 위성 채널 시뮬레이터로 시험하여 검증하였다. 제안된 IP 모뎀은 휴대형으로 설계 되어 어느 곳에서든지 Internet 통신환경을 제공할 수 있다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권2호
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• pp.149-154
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• 2004

In this research, we selected the speech recognition to implement the electric wheelchair system as a method to control it by only using the speech and used DTW (Dynamic Time Warping), which is speaker-dependent and has a relatively high recognition rate among the speech recognitions. However, it has to have small memory and fast process speed performance under consideration of real-time. Thus, we introduced VQ (Vector Quantization) which is widely used as a compression algorithm of speaker-independent recognition, to secure fast recognition and small memory. However, we found that the recognition rate decreased after using VQ. To improve the recognition rate, we applied ART2 (Adaptive Reason Theory 2) algorithm as a post-process algorithm to obtain about 5% recognition rate improvement. To utilize ART2, we have to apply an error range. In case that the subtraction of the first distance from the second distance for each distance obtained to apply DTW is 20 or more, the error range is applied. Likewise, ART2 was applied and we could obtain fast process and high recognition rate. Moreover, since this system is a moving object, the system should be implemented as an embedded one. Thus, we selected TMS320C32 chip, which can process significantly many calculations relatively fast, to implement the embedded system. Considering that the memory is speech, we used 128kbyte-RAM and 64kbyte ROM to save large amount of data. In case of speech input, we used 16-bit stereo audio codec, securing relatively accurate data through high resolution capacity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권9호
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• pp.4389-4411
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• 2018

High dynamic range (HDR) images are becoming pervasive due to capturing or rendering of a wider range of luminance, but their special display equipment is difficult to be popularized because of high cost and technological problem. Thus, HDR images must be adapted to the conventional display devices by applying tone mapping (TM) operation, which puts forward higher requirements for intellectual property protection of HDR images. As the robustness presents regional diversity in the low dynamic range (LDR) watermarked image after TM, which is different from the traditional watermarking technologies, a concept of watermarking activity is defined and used to distinguish the essential distinction of watermarking between LDR image and HDR image in this paper. Then, a novel robust HDR image watermarking algorithm is proposed against TM operations. Firstly, based on the hybrid processing of redundant discrete wavelet transform and singular value decomposition, the watermark is embedded by modifying the structure information of the HDR image. Distinguished from LDR image watermarking, the high embedding strength can cause more obvious distortion in the high brightness regions of HDR image than the low brightness regions. Thus, a perceptual brightness mask with low complexity is designed to improve the imperceptibility further. Experimental results show that the proposed algorithm is robust to the existing TM operations, with taking into account the imperceptibility and embedded capacity, which is superior to the current state-of-art HDR image watermarking algorithms.

• 한국태양에너지학회 논문집
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• 제32권spc3호
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• pp.255-261
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• 2012

Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. And also, the switch device is not ideal, both each switching element of the voltage drop difference and on & off time delay difference generate DC offset. Thus, to compensate for deadtime and the switch voltage drop, feedback control by output current DC offset should be provided to compensate additional distortion of the output current. The validity of the proposed method is confirmed through PSIM simulation.

• 제어로봇시스템학회논문지
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• 제20권2호
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• pp.193-199
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• 2014

In this paper, we present an overview of the structure of a lab-built powered knee prosthesis and the control of it. We build a powered prosthesis prototype on the basis of previous researches and aim at obtaining the essential technology related with its control. We adopt the slider-crank mechanism with a DC motor as an actuator to manipulate the knee joint. We also build an embedded control system for the prosthesis with a 32-bit DSP controller as a main computation unit. We divide the gait phase into five stages and use a FSM (Finite State Machine) to generate a torque reference needed for each stage. We also propose to use a position-based impedance controller for driving the powered knee prosthesis stably. We perform some walking experiments at fixed speeds on a tread mill in order to show the feature of the built powered prosthesis. The experimental results show that our prosthesis has the ability to provide a functional gait that is representative of normal gait biomechanics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1936-1939
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• 2004

This paper proposes streaming layer for personal robot's middleware. Under assumption that robot has open architecture, i.e. consists of modules created by different vendors and intercommunication between these modules is necessary, we have to consider that there are many different network interfaces. To make communication between modules possible it is necessary to develop new type of middleware. Such middleware has to support different platforms, i.e. OS, network interface, hardware, etc. In addition, it is necessary to implement effective interface between network and application in order to manage inter application communications and use network resources more effectively. Streaming layer is such interface that implements necessary functionality together with simplicity and portability. Streaming layer provides high level of abstraction and makes communication between distributed applications transparent as if are located in same module. With possibility of extension by user defined application interfaces it is suitable for distributed environments, i.e. module based architecture including small-embedded systems like as DSP board. To verify the proposed streaming layer structure it is implemented using C and tested.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.580-585
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• 2005

A QRT(Quad-Rotor Type) hovering robot system is developed for quick detection and observation of the circumstances under calamity environment such as indoor fire spots. The UAV(Unmanned Aerial Vehicle) is equipped with four propellers driven by each electric motor, an embedded controller using a DSP, INS(Inertial Navigation System) using 3-axis rate gyros, a CCD camera with wireless communication transmitter for observation, and an ultrasonic range sensor for height control. The developed hovering robot shows stable flying performances under the adoption of RIC(Robust Internal-loop Compensator) based disturbance compensation and the vision based localization method. The UAV can also avoid obstacles using eight IR and four ultrasonic range sensors. The VTOL(Vertical Take-Off and Landing) flying object flies into indoor fire spots and sends the images captured by the CCD camera to the operator. This kind of small-sized UAV can be widely used in various calamity observation fields without danger of human beings under harmful environment.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.182-187
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• 2012

Since PV PCS uses output current sensor for ac output current control, the sensor's sensing value includes unnecessary offset inevitably. If PV inverter is controlled by the included offset value, it's output current will generate DC offset. The DC offset of output current for trans-less PV inverter is fatal to grid, which results in saturating grid side transformer. Usually DSP controller of PV inverter reads several times sensing value during initial operation and, finally, it's average value is used for offset calibration. However, if temperature changes, the offset changes, too. Therefore, output current sensor measures sensing value that includes offset again. In this paper we propose new algorithm where two identical forward and reverse sensors are used to calculate the offset in real time. As a result the offset is not correlated with temperature change. The proposed algorithm is verified through PSIM simulation for validity.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 추계학술발표대회 및 정기총회
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• pp.1433-1436
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• 2005

임베디드 시스템의 발전으로 현재 진보된 로봇 시스템들은 운영 체제, 비젼 시스템 및 센서 시스템들을 별도의 호스트 PC의 도움 없이 독립적으로 탑재하여 가동 시킬 수 있다. 본 논문에서는 임베디드 시스템을 이용한 SBER (Small Biped Entertainment Robot)에 필요한 로봇의 제어기 구조와 로봇에 최적화된 임베디드 시스템을 구현한다. 또한 주 프로세서와 주 컨트롤러를 탑재한 최적화된 소형 엔터테인먼트 이족 로봇 개발을 목적으로 한다. SBER은 TI사의 DSP인 TMS320LF2407A를 로봇의 주 컨트롤러로 사용하여 로봇의 관절 제어를 통한 기본적인 보행 실험과 음원의 위치를 파악하기 위한 음원 위치 추적 문제를(Sound Localization) 수행한다. 또한 Intel사의 PXA255A를 주 프로세서로 사용하여 연산량이 높은 영상처리 알고리즘과 감정 표현, 장애물 인식 및 장애물 회피를 적용하여 보다 지능적인 로봇 시스템을 구현한다.

• 한국정보통신학회논문지
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• 제2권3호
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• pp.417-429
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• 1998

동영상 압축 기술 및 디지털 신호처리 기술의 발전으로 인해 댁내의 가전 기기들이 점차 디지털화되고 고속의 통신 기능이 탑재되는 정보 가전으로 발전하고 있다. 그러나, 댁내 ATM 망의 규모 및 기능은 아직 표준화 단체에서도 표준화를 진행 중에 있고 확정적인 모델은 정의되지 않았으므로 어느 특정한 모델을 정립하기에는 어려움이 있다. 본 논문에서는 댁내 ATM 망을 설계하기 위하여 적합한 토폴로지 구조를 메쉬형, 트리형, 링형으로 선정하고 각각의 댁내 망 구조 및 기능의 특징과 성능을 비교함으로써 댁내 ATM 망 설계 방안을 제시한다.