• Journal of Institute of Control, Robotics and Systems
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• v.18 no.6
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• pp.546-554
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• 2012

This paper suggests a design method of an improved phase control loop for tracking resonant frequency of solid type precision resonant gyroscope. In general, a low cost MEMS gyroscope adapts the automatic gain control loops by taking a velocity feedback configuration. This control technique for controlling the resonance amplitude shows a stable performance. But in terms of resonant frequency tracking, this technique shows an unreliable performance due to phase errors because the AGC method cannot provide an active phase control capability. For the resonance control loop design of a solid type precision resonant gyroscope, this paper presents a phase domain control loop based on linear PLL (Phase Locked Loop). In particular, phase control loop is exploited using a higher order PLL loop filter by extending the first order active PI (Proportion-Integral) filter. For the verification of the proposed loop design, a hemispherical resonant gyroscope is considered. Numerical simulation result demonstrates that the control loop shows a robust performance against initial resonant frequency gap between resonator and voltage control oscillator. Also it is verified that the designed loop achieves a stable oscillation even under the initial frequency gap condition of about 25 Hz, which amounts to about 1% of the natural frequency of a conventional resonant gyroscope.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.12
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• pp.2315-2320
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• 2006

A real-time frame-layer rate control algorithm with a token bucket traffic shaper is proposed for low bit rate video coding. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. In order to reduce the quality fluctuation, we use a sliding window scheme which does not require the pre-analysis process. Therefore, the proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder. Experimental results indicate that the proposed control method provides better visual and PSNR performances than the existing rate control method.

• The Korean Journal of Food And Nutrition
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• v.29 no.5
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• pp.801-807
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• 2016

In Western countries, kimchi, the Korean traditional fermented cabbage, is considered to be a healthy. However, it is one of the main sources of the high sodium content of the Korean diet. In order to decrease the sodium content, we manufactured a low-sodium kimchi (LK, salinity 1.0%) and 4 additional low-sodium kimchi starters in which each of 4 lactic acid bacteria (Lb. sakei 1, Lb. sakei 2, Lb. palntarum and W. koreensis) were added. The LKL1 to LKL4 samples were prepared by adding 4 single LAB starters, each with an inoculum size of $10^6CFU/g$, when the cabbage was mixed with kimchi sauce. The kimchi starters were fermented at $10^{\circ}C$ until reaching 0.5% acidity, and then stored at $-1.5^{\circ}C$ until reaching 0.75% acidity. The pH and acidity of the starter kimchi changed more rapidly in the early phase of fermentation (up to 0.75% acidity) than control low-sodium kimchi. After the acidity of the kimchi starters reached 0.75% it remained constant. As the fermentation progressed, the total aerobic and lactic acid bacteria concentrations in the kimchi starter with added Lb. sakei 1 were the same as in the control low-sodium kimchi. The low-sodium kimchi fermentation of the kimchi starter with added Lb. palntarum progressed differently due to a difference in acid resistance. The kimchi starter with added Lb. sakei 2 had an overall liking score that was slightly higher than that of the control low-sodium kimchi due to a lower off-flavor.

• Journal of Power Electronics
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• v.19 no.1
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• pp.168-178
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• 2019

Discrete space vector modulation (DSVM) is an effective method to improve the steady-state performance of the finite control set predictive control for permanent magnet synchronous motor drive systems. However, it requires complex computations due to the presence of numerous virtual voltage vectors. This paper proposes an improved finite control set model-free predictive control using DSVM to reduce the computational burden. First, model-free deadbeat current control is used to generate the reference voltage vector. Then, based on the principle that the voltage vector closest to the reference voltage vector minimizes the cost function, the optimal voltage vector is obtained in an effective way which avoids evaluation of the cost function. Additionally, in order to implement double-objective control, a two-level decisional cost function is designed to sequentially reduce the stator currents tracking error and the inverter switching frequency. The effectiveness of the proposed control is validated based on experimental tests.

• Journal of the Korean Solar Energy Society
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• v.34 no.6
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• pp.103-109
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• 2014

It is important to control the amount of supply water flow rate at all kinds of HVAC systems in order to maintain IAQ and energy efficiency. The most of buildings installed geothermal heat pumps is using fixed water flow rate in spite of the excellent performance of geothermal heat pumps. Especially when the air-conditioning load is low, the flow rate control may be possible to save energy to operate. However, it is effective to apply the variable flow control system in order to reduce energy consumption. Therefore, the purpose of this study, change a water flow rate and improve the whole performance of the geothermal heat pump. Geothermal heat pump system is modeled after the selection of the applied building, by setting the flow rate control to be analyzed through a simulation of performance evaluation. Building energy saving according to the flow rate of the ground circulating water analyze quantitatively and to investigate the importance of the flow control.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.301-306
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• 2003

PID controller is applied mostly to two-order system. In third-order or higher- system, it's impossible to get high response quality because of having more zero point than the number of zero point being in the PID controller. To solve those, Jung & Dorf suggested a new type of PIDA controller and solved problen of a third-order system. But, as the result of getting step response using PIDA controller, rising time is very quickly but wide overshoot is happened. Beside designing PIDA controller with using CDM(Coefficient Diagram Method) suggested by shunji manabe. But, In Performance standard, CDM decreases overshoot to desired but rising time is very slow. Therefore this paper suggest a PD-PIDA controller for low overshoot with PD type Pre-compensator. This paper applied designed PD-PIDA controller to position control of 3-Phase induction motor.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1521-1523
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• 2005

PID controller is applied mostly to two-order system. In third-order or higher- system, it's impossible to get high response quality because of having more zero point than the number of zero point being in the PID controller. To solve those, Jung & Dorf suggested a new type of PIDA controller and solved problen of a third-order system.. But, as the result of getting step response using PIDA controller, rising time is very quickly but wide overshoot is happened. Beside designing PIDA controller with using CDM(Coefficient Diagram Method) of Shunji Manabe decreases overshoot to desired but rising time is very slow. Therefore this paper suggest a I-PDA controller for low overshoot and fast responsibility. This paper applied designed PD-PIDA controller to position control of 3-Phase induction motor.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.5
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• pp.630-635
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• 1998

The objective of this paper is to propose a new efficient technique for the estimation of time-delay parameters using wavelet theory and third-order cumulants, yielding good performance even in the case of low SNR. In particular, band-limited non-Gaussian signals with non-zero skewness and spatially correlated Gaussian noises are considered here. The approach is based on the fact that the effects of spatially correlated Gaussian noises on time-delay estimation can be reduced by using the projection sequences (based on the redundant wavelet decomposition) of given measurements in the higher-order cumulant domain. Finally, the performance of the proposed approach is demonstrated using simulations.

• 전기의세계
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• v.18 no.1
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• pp.15-23
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• 1969

A lot of recent researches have shown that a Pseudo Random Binary Signal is a quite effective test signal to measure the impulse response of a plant. Generally speaking, however, such a response itself is not satisfactory to determine the appropriate control parameters or control inputs. Here, the author intends to estimate the unknown parameters of the First Order Plant with Dead Time by means of correlation method using M-sequence signal. The time constant T and the dead time L of the plant are eatimated with one tracking loop by automatically adjusting delay time .tau. of M-sequence signal according to variations of T and L. In this paper, a three level M-sequence signal is used as a test signal in order to avoid troublesome operations to calculate partial derivatives of a given performance index with respect to the parameters which are usually required in the Model Method. Several experiments with analogue computer using low pass filters as averaging circuits showed good results as expected.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.3
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• pp.222-226
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• 2010

In this paper we study the consensus problem of SISO (Single-Input Single-Output) linear multi-agent systems under a fixed weighted undirected network communication. The dynamics of each agent can be of any order, while it is constrained to be neutrally stable. Based on a simple root locus argument, we show that the problem at hand is always solvable if the gain and zeros of the dynamic compensator, of which dimension is the same as the number of plant poles on the imaginary axis, are chosen suitably, finally the result is successfully verified by an example.