• 전자공학회논문지S
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• 제34S권7호
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• pp.1-8
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• 1997

In this paper, Stokes parameters which represent the states of polarization of transmitted light are determined by potential function, which is used to obtain signals points in a multidimensional Euclidean structure. And performance of multilevel polarization shift keying(POLSK) system using the obtained parameters is also represented and analyzed. As results, bit error rate of multilevel POLSK system using the potential function is shown to be lower than the conventional one using the distance matrix. And as number of levels increases, the number of photons per bit for bit error rate of 10$^{-9}$ is also increased linearly. The multilevel POLSK system, therefore, is an energy efficient modulation technque as compared with the convnetional ones.

• ETRI Journal
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• 제32권5호
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• pp.774-783
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• 2010

Many chaos-based encryption methods have been presented and discussed in the last two decades, but very few of them are suitable to secure transmission on noisy channels or respect the standard of the National Institute of Standards and Technology (NIST). This paper tackles the problem and presents a novel chaos-based cryptosystem for secure transmitted images. The proposed cryptosystem overcomes the drawbacks of existing chaotic algorithms such as the Socek, Xiang, Yang, and Wong methods. It takes advantage of the increasingly complex behavior of perturbed chaotic signals. The perturbing orbit technique improves the dynamic statistical properties of generated chaotic sequences, permits the proposed algorithm reaching higher performance, and avoids the problem of error propagation. Finally, many standard tools, such as NIST tests, are used to quantify the security level of the proposed cryptosystem, and experimental results prove that the suggested cryptosystem has a high security level, lower correlation coefficients, and improved entropy.

• 한국정밀공학회지
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• 제13권10호
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• pp.123-129
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• 1996

Computed torque method has been used for precise trajectory control of the robotic system that involves nonlinear dynamics. It is hard to know exact values of robot system parameters, and the robot arm receives umpredictable interference from the working environment. These disturbances, especially in a direct drive robot, are directly transmitted to actuating motor without reduction. Modelling error and distrubance can cause significant errors in a trajectory tracking problem. In this paper, we propose a new controller that $H_{\infty}$controller is conbined to robot system linearized by computed torque. Simula- tions are made for comparing the performance of the proposed controller with that of a nonlinear $H_{\infty}$ controller proposed by Chen and also computed torque method.hod.

• 한국조명전기설비학회지:조명전기설비
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• 제9권6호
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• pp.78-82
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• 1995

It is needed to robust control for D.C. servo motor according to industrial automation. However, when a motor has an effect of disturbance and variable load, it is very difficult to guarantee the robustness of the system. as a compensation way of solving this problem, in this paper, a expert supervisory control method for motor control system is presented. Expert supervisory controller is designed by error and error change, and nth control input is decided by the addition of (n-1)th control input and inference amount of increase or decrease. Control input of expert supervisory control is transmitted to input, and the disturbance effect decrease remarkable by control input. The robustness of D.C. servo motor using expert supervisory control is demonstrated by the computer simulation.

• 대한의용생체공학회:의공학회지
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• 제7권1호
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• pp.53-58
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• 1986

This paper represent the design of a digital modem which transmits the ECG data from an ambulatory arrhythmia monitor over the telephone lines to a large hospital for the instantaneous interpretations. The digital modem provides on-line communications between the patient and the central computer located near cardiologists. For commercial telephone lines, the transmitting error rates of the digital modem were measured 200 times at a speed of 300 baud. In those measurements, the block errors-results, due to the misinterpretation of start and stop bits, did not occur, The data bit errors which were due to a single bit interpreted incorrectly were 0.78 (bits/10 ) . Since the acceptable data bit error limit is 10 per 106 bits transmitted, the digital modem designed in this paper can be used for the clinical applications without any difficulty.

• 전기전자학회논문지
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• 제21권2호
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• pp.130-135
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• 2017

Normally, in data transmission, extra parity bits are added to the input message which were derived from its input and a pre-defined algorithm. The same algorithm is used by the receiver to check the consistency of the delivered information, to determine if it is corrupted or not. It recovers and compares the received information, to provide matching and correcting the corrupted transmitted bits if there is any. This paper aims the following objectives: to use an alternative error detection-correction method, to lessens both the fixed number of the required redundancy bits 'r' in cyclic redundancy checking (CRC) because of the required polynomial generator and the overhead of interspersing the r in Hamming code. The experimental results were synthesized using Xilinx Virtex-5 FPGA and showed a significant increase in both the transmission rate and detection of random errors. Moreover, this proposal can be a better option for detecting and correcting errors.

• 한국통신학회논문지
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• 제21권5호
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• pp.1274-1282
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• 1996

This paper deals with an inverse modeling of nonminimum phase communication channel utilizing the HOS (High Order Statistics) of the received signal. After the communication channel is separated into the minimum phase and maximum phase components, the inverse modeling is performed independently. The performance superiority is confirmed by monte-carlo computer simulation in comparison with the traditional CMA (Constant Modulus Algorithm) method. By utilizing the proposed algorithm employing the HOS of the received signal, the inverse frequency characteristics of the channel can be obtained withoug transmitted signal in digital communication. This algorithm is required in preprocessing or postprocessing in order to remove the channel effect, and effective in the self adaptive equalizer which can minimize the bit error rate or symbol error rate in the recovry of received signal.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.158.5-158
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• 2001

Monopulse active homing radar requires velocity and angle information of target to track fast moving target. Target velocity can be estimated by measuring the frequency shift between transmitted and received frequencies. Angle information is obtained by measuring boresight error. Measurement of doppler frequency component in received signal is done through FFT analysis and interpolation algorithm for fine tuning. Boresight errors in azimuth and elevation axes are proportional to the power of each difference channel relative to sum channel. The target signal power in difference channel is estimated more precisely by measuring the power of FFT result cell of maximum ...

• 전자공학회논문지B
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• 제32B권3호
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• pp.1-10
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• 1995

In this paper, a fault-tolerant Mini-MAP system with high reliability is proposed. For fault-tolerance, the LLC sublayer, MAC sublayer, and physical layer of the Mini-MAP system are dualized. The detection of faults, the replacement of the failed network, and the management of the network are three major functions required for the dualization, and they are performed by ESM(Error Supervisory Machine), EMM(Error Management Machine), and NMM(Network Management Machine) of the proposed fault-tolerant Mini-MAP system, respectively. The ring maintenance function of the MAC sublayer is used for the detection of the faults. In the proposed fault-tolerant Mini-MAP system, the data are received from both of the dualized networks and transmitted to the selected one of the two. We analyze the reliability and the MTTF(Mean Time To Failure) of the proposed fault-tolerant Mini-MAP system and show that it has better performance compared to a general Mini-MAP system.

• 전기학회논문지
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• 제57권2호
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• pp.286-293
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• 2008

The design and implementation of a personal navigation system including activity monitoring function is given in this paper. The system consists of a 3 dimensional MEMS accelerometer, digital compasses and ZigBee communication. An accelerometer and digital compasses are used to compute the position and activity. The obtained position and activity information is transmitted to a fixed beacon via ZigBee. At the same time, activity information is stored in the personal navigation system to a batch analysis program. The step detection algorithm which is robust to attaching location is proposed. Also two digital compass error compensation algorithms are proposed to find more precise headings. The experiments with a real system show that the activities of users and continuous locations less than 1.5m errors are obtained after 80m walking.