• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.434-439
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• 2019

This paper proposed a control algorithm to compensate the delay time to improve the signal to noise, and the proposed control algorithm estimate the target information to apply the continuous wave radar equation. The proposed control algorithm improves the output signal of each array element bv multiplying the weight of the receive signal to the signal to noise ratio. Radar radiate a signal in spatial and the target information is estimated by the echoed signal from the target. But the signal in the wireless communication environment occurs the delay time due to the multipath which appear human and natural structures. It is difficult to accurately estimate the desired information because of the degradation for the system performance due to the interference signal and the signal distortion. The target information can be improved by compensating the delay signal to apply the weight to the received signal by using the uniform linear array antenna. As a simulation result, we show that the performance of the proposed control algorithm and the non-compensated delay time are compared. The proposed control algorithm proved that the target distance estimation information is improved.

• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.295-299
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• 2007

This paper presents the ASF(Additional Secondary Factor) modeling of DGPS beacon signal. In addition to DGPS's original purpose, the feasibility to utilize DGPS system for timing and navigation has been studied. For timing and navigation, the positioning system must know the accurate time delay of signal traveling from the transmitter to receiver. Then the delay can be used to compute the user position. The DGPS beacon signal transmits the data using medium frequency, which travels through the surface and cause the additional delay rather than the speed of light according to conductivities and elevations of the irregular terrain. We introduce the modeling of additional delay(ASF) and present the results of implementation. The similar approach is Locan-C. Loran-C has been widely used as the maritime location system and was enhanced to E-Loran(Enhanced Loran). E-Loran system uses the ASF estimation method and is able to provide the more precise location service. However there was rarely research on this area in Korea. Hence, we introduce the ASF and its estimation model. With the comparison of the same condition and data from the original Monteath model and ASF estimation data of Loran system respectively, we guarantee that the implementation is absolutely perfect. For further works, we're going to apply the ASF estimation model to Korean DGPS beacon system with the Korean terrain data.

• Journal of Cadastre & Land InformatiX
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• v.51 no.1
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• pp.97-110
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• 2021

This study estimated the delay factor, which is the ratio of travel time at the speed limit and travel time at the actual speed using real-time traffic information in Seoul. The actual travel speed on the road was lower than the maximum speed of the road and the travel speed was the slowest during the rush hour. As a result of accessibility analysis based on travel speed during the rush hour, the travel time at the actual speed was 37.49 minutes on average. However, the travel time at the speed limit was 15.70 minutes on average. This result indicated that the travel time at the actual speed is 2.4 times longer than that at the speed limit. In addition, this study proposedly defined the delay factor as the ratio of accessibility by the speed limit and accessibility to actual travel speed. As a result of delay factor analysis, the delay factor of Seoul was 2.44. The results by the administrative district showed that the delay factor in the north part areas of the Han River is higher than her south part areas. Analysis results after applying the relationship between road density and traffic volume showed that as the traffic volume with road density increased, the delay factor decreased. These results indicated that it could not be said that heavy traffic caused longer travel time. Therefore, follow-up research is needed based on more detailed information such as road system shape, road width, and signal system for finding the exact cause of increased travel time.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.6
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• pp.550-556
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• 2009

In an application of a time reversal(TR) focusing of array transducer on a defect inside the test material, we employ a new time delay focusing technique based the TR process. In order to realize this idea, a multi-channel ultrasonic system is constructed capable of applying necessary time delays to each channel. The TR-based focusing procedure first measures the backscattered signals after firing one of the array elements. A phase slope method is then used to determine the time-of-flights of the backscattered signals received by all elements of the array. These time delays are used to adjust the time of excitation of the elements for transmission focusing on the defect. In addition to the TR focusing, the classical phased array focusing is also considered for comparison. Experimental results show that the TR-based time delay focusing produces much stronger backscattered signals than the phased array focusing, demonstrating the enhanced capability of the TR focusing.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.1
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• pp.1-8
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• 2004

The INS(Inertial Navigation System) provides high rate position, velocity and attitude data with good short-term stability while the GPS(Global Position System) provides position and velocity data with long-term stability. By integrating the INS with GPS, a navigation system can be achieved to Provide highly accurate navigation Performance. For the best performance, time synchronization of GPS and INS data is very important in GPS/INS integrated system But, it is impossible to synchronize them exactly due to the communication and computation time-delay. In this paper, to reduce the error caused by the measurement time-delay in GPS/INS integrated systems, error compensation methods using separate bias Kalman filter are suggested for both the loosely-coupled and the tightly-coupled GPS/INS integration systems. Linearized error models for the position and velocity matching GPS/INS integrated systems are Int derived by linearizing with respect to its time-delay and augmenting the delay-state into the conventional state equations for each case. And then separate bias Kalman Inter is introduced to estimate the time-delay during only initial navigation stage. The simulation results show that the present method is effective enough resulting in considerably less position error.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1271-1279
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• 2017

A highly accurate model-free controller is proposed for trajectory tracking control of robot manipulators. The proposed controller incorporates time-delay estimation (TDE) to estimate and cancel continuous nonlinearities of robot dynamics, and exploits fuzzy logic systems to suppress the effect of the TDE error, which is due to discontinuous nonlinearities such as friction. To this end, integral sliding mode is defined using desired error dynamics, and a Mamdani-type fuzzy inference system is constructed. As a result, the proposed controller achieves the desired error dynamics well. Implementation of the proposed controller is easy because the design of the controller is intuitive and straightforward, and calculations of the complex robot dynamics are not required. The tracking performance of the proposed controller is verified experimentally using a 3-degree of freedom PUMA-type robot manipulator.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.1
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• pp.17-23
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• 2020

We propose a system time synchronization method between embedded Linux-based distributed control devices by using Transmission Control Protocol (TCP) communication and General Purpose Input Output (GPIO) device. The GPIO signal is used as the trigger signal for synchronization and the TCP communication is used to transfer the system time of master Linux, which serves as the reference clock, to slave Linux. Precise synchronization performance is achieved by measuring and compensating for the propagation delay of GPIO signal and the acquisition and setting latency of Linux system time. We build an experimental setup consisting of two embedded Linux systems, and perform extensive experiments to verify the performance of the proposed synchronization method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12A
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• pp.1246-1252
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• 2006

In this paper, a collision probability, processing time and traffic capacity analysis algorithm for RFID system using random FHSS and synchronous FHSS is proposed. Service time, duty cycle, traffic intensity and additional delay time required for re-transmission due to collision are considered and the processing delay and frequency channel capacity are analyzed for the steady state operation of the system. The simulation results which show maximum capacity of the system and explain the accuracy of the algorithm are provided.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.89-91
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• 2007

In this paper, a new approach for a sampled-data representation of nonlinear system that has time-delayed multi-input is proposed. That is largely devoid of illconditioning and is suitable for any nonlinear problem. The new scheme is applied to nonlinear systems with two or three inputs; and then the delayed multi-input general equation is derived. The method is based on thematrix exponential theory. Itdoes not require excessive computational resources and lends itself to a short and robust piece of software that can be easily inserted into large simulation packages. A performance of the proposed method is evaluated using a nonlinear system with time-delay: maneuvering an automobile.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.117-120
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• 2001

Deadbeat property is well established in digital control system design, But in continuous time, it can hardly realized for it's asymtotic property. But recently japanese researchers suggested serveral method for continuous time deadbeat property. They use delay elements In polynomials and established for the deadbeat condition. By solving this condition, unknown coefficients in polynomials with delay elements is obtained. In this paper, design method for optimal continuous time deadbeat servo system using 2nd order smooting elementsis studied. Continuous time deadbeat controller is consisted of serial integral compensator and local feedback one in state feedback loop. Determining method for damping rations and natural frequencies of smothing elements is described. By computer simulations, control inputs and system outputs are shown to have desirable property such as smoothness.