• Electronics and Telecommunications Trends
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• v.34 no.4
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• pp.89-97
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• 2019

The olfactory bio technology is largely based on its corresponding recognition technology and smell stimulus that acquires, analyzes, and processes volatile organic compounds present in chemical molecules, which are present in the breath or air evoked by an electronic nose artificially imitating the human biological nose. The olfactory bio technology is also based on a scent display technology that automatically diverges various digital flavors based on aesthetics, concentration, duration, and intensity information required to enhance the sensibility using a computer. Recently, attempts have been made to apply noninvasive screening of dementia by sensing, analyzing, encoding, and transmitting bio information obtained through an olfactory interface, both domestically and externally; further, the olfactory medical content technology has been applied to delay or reduce the onset of dementia. In this study, we will focus on early screening of dementia using olfactory biology information and dementia cognitive enhancer content that delays or reduces the onset of dementia.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.218-223
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• 1993

In this paper, we present a full digital control scheme which controls currents and speed of the permanent magnet AC servo motor with large range of bandwidth and high performance. The current equations of the permanent magnet AC servo motor are linearized by feedback linearization technique. Both acceleration feedforward terms and IP controllers, whose gains are functions of motor speed, are used in order to control motor currents. In addition the phase delays in current control loops are compensated by placing phase lead-lag compensators after current commands, which make it possible to avoid high gains in the current controllers. Unity power factor can be achieved by the proposed current controller. Pulsewidth modulation is performed by way of the well-known comparison with a triangular carrier signals. The velocity controller is designed on the basis of the linearized model of the permanent magnet AC servo motor by the proposed current controller. The performance of the entire control system is analyzed in the presence of uncertainty in the motor parameters. The proposed control scheme is implemented using the digital signal processor-based controller composed of an Analog Device ADSP 2111 and a NEC78310. The pulsewidth modulation (PWM) signals are generated through a custom IC, SAMSUNG-PWM1, which has the outputs of current controllers as input. The experimental results show that the permanent magnet AC servo motor can be always driven with high dynamic performance by the proposed full digital control scheme of motor speed and motor current.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.4
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• pp.1042-1058
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• 2024

Terahertz (THz) communication is becoming a key technology for future 6G wireless networks because of its ultra-wide band. However, the implementation of THz communication systems confronts formidable challenges, notably beam splitting effects and high computational complexity associated with them. Our primary objective is to design a hybrid precoder that minimizes the Euclidean distance from the fully digital precoder. The analog precoding part adopts the delay-phase alternating minimization (DP-AltMin) algorithm, which divides the analog precoder into phase shifters and time delayers. This effectively addresses the beam splitting effects within THz communication by incorporating time delays. The traditional digital precoding solution, however, needs matrix inversion in THz massive multiple-input multiple-output (MIMO) communication systems, resulting in significant computational complexity and complicating the design of the analog precoder. To address this issue, we exploit the characteristics of THz massive MIMO communication systems and construct the digital precoder as a product of scale factors and semi-unitary matrices. We utilize Schatten norm and Hölder's inequality to create semi-unitary matrices after initializing the scale factors depending on the power allocation. Finally, the analog precoder and digital precoder are alternately optimized to obtain the ultimate hybrid precoding scheme. Extensive numerical simulations have demonstrated that our proposed algorithm outperforms existing methods in mitigating the beam splitting issue, improving system performance, and exhibiting lower complexity. Furthermore, our approach exhibits a more favorable alignment with practical application requirements, underlying its practicality and efficiency.

• Smart Structures and Systems
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• v.25 no.5
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• pp.569-580
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• 2020

The identification of delays and delay compensation are critical problems in real-time hybrid simulations (RTHS). Conventional delay compensation methods are mostly based on the assumption of a constant delay. However, the system delay may vary during tests owing to the nonlinearity of the loading system and/or the behavioral variations of the specimen. To address this issue, this study presents an adaptive delay compensation method based on a discrete model of the loading system. In particular, the parameters of this discrete model are identified and updated online with the least-squares method to represent a servo hydraulic loading system. Furthermore, based on this model, the system delays are compensated for by generating system commands using the desired displacements, achieved displacements, and previous displacement commands. This method is more general than the existing compensation methods because it can predict commands based on multiple displacement categories. Moreover, this method is straightforward and suitable for implementation on digital signal processing boards because it relies solely on the displacements rather than on velocity and/or acceleration data. The virtual and real RTHS results show that the studied method exhibits satisfactory estimation smoothness and compensation accuracy. Furthermore, considering the measurement noise, the low-order parameter models of this method are more favorable than that the high-order parameter models.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.70-73
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• 2002

High frequency digital LSI circuits are usually composed of many sub-circuits coupled with interconnects. They sometimes causes serious problems of the fault switching by time-delays, crosstalks, reflections of signals and so on. Therefore, it is very important to develop a user-friendly simulator for solving these problems. Although a moment matching method is widely used as the reduction technique of interconnects, it may happen to arise erroneous results for evaluating the poles far from the origin. In this paper, we show an asymptotic method in the complex frequency-domain, where we calculate the exact poles and residues giving large effect to the transient responses. Then, the interconnects are replaced by the asymptotic equivalent circuits using the poles and residues. Thus, we can develop a users-friendly simulator using the equivalent circuits.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.7
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• pp.475-483
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• 1988

One of the advantages of the well-known PID controller is that it is a sufficiently flexible controller for many applications. But, when the plant parameters and disturbances are unknown or change with time, it is desirable to make automatic tuning of PID controller in order to achieve an acceptable level of performance of the control system. This paper presents a reformulation of the self-tuning pole-zero placement controller subject to some conditions and restrictions. It has the structure of a digital PID controller and is based on Vogel and Edgar's pole-zero placement design method. Various properties of this self-tuning PID controller are described and illustrated by simulation examples.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.1-6
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• 1993

This report proposes a novel method of identification of continuous time-delay systems from sampled input-output data. By the aid of a digital pre-filter, an approximated discrete-time estimation model is first derived, in which the system parameters remain in their original form and the time delay need not be an integral multiple of th sampling period. Then an identification method combining the common linear least squares(LS) method or the instrumental variable(IV) method with the genetic algorithm(GA) is proposed. That is, the time-delay is selected by the GA, and the system parameters are estimated by the LS or IV method. Furthermore, the proposed method is extended to the case of multi-input multi-output systems where the time-delays in the individual input channels may differ each other. Simulation resutls show that our method yields consistent estimates even in the presence of high measurement noises.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.598-601
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• 2001

As many sensors and actuators are used in many automated system, various industrial networks are adopted for digital control system. In order to take advantages of the networking, however, the network implementation should be carefully designed to satisfy real-time requirements considering network delays. This paper presents the implementation scheme of a networked control system via Profibus-DP network. More specifically, the effect of the network delay on the control performance was evaluated on a Profibus-DP testbed, and a GA based PID tuning algorithm is proposed to demonstrate the fesibility of the networked control system.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.584-589
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• 1988

Tuning of digital STC parameters for the system with unknown and time varying parameters as well as delays presents many preconditions and difficulties. In order to eliminate these difficulties and to enhance STC control functions, the present study employs the metbod of expert control for STC and to implement it in nod-minimum phase plants. In this paper, implimedtation of the Expert STC for process control, STC. parameters is carried out by tuning systematically and by applying these parameters to non-minimum phase plant. This controller supervises a status of the plant, and robust control function for time delay or change of the plant is demonstrated by computer simulations.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.87-90
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• 2000

This paper describes a register-controlled symmetrical delay-locked-loop (DLL) using hybrid delay line for use in a high frequency double-data-rate DRAM. The proposed DLL uses a hybrid delay line which can cover two-step delays(coarse/fine delay) by one delay element. The DLL dissipate less power than a conventional dual-loop DLL which use a coarse and a fine delay element and control separately. Additionally, this DLL not only achieves small phase resolution compared to the conventional digital DLL's when it is locked but it also has a great simple delay line compared to a complex dual-loop DLL.