• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.4 no.5
• /
• pp.963-969
• /
• 2000

In this paper, we define two input-output gains of linear periodic time-varying systems. One is the ratio of output with worst-case l2-norm over all inputs with unit 12-norm. It denotes G($\iota_2,\iota_2$.The other is the ratio of output with worst-case RMS value over all inputs with unit RMS value. It denotes G(RMS, RMS) .It is fact that these two gains are equivalent for linear time-invariant system. In this paper, we prove these two gains are also equivalent for linear periodic time-varying system. In addition, the relationship between two method of obtaining the generalized frequency responses for linear periodic time-varying system is derived. Finally, we apply the defined input-output gains to M-channel filter-bank which is multi-rate signal Processing system, used to speech coding. In the filter-bank, generally, aliasing distortion, magnitude distortion, and phase distortion are present. It is shown that these are kept small if the filter-bank is designed by a method that optimizes the gain G($\iota_2,\iota_2$ of an error system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.4
• /
• pp.688-697
• /
• 2017

It is very difficult to solve mathematically the optimal control problem for non - linear mobile robots to move to target points with minimum energy related to velocity, acceleration and angular velocity in minimum time. This paper proposes a method to obtain optimal control gains with which mobile robots move with minimum energy related to velocity, acceleration and angular velocity in minimum time using genetic algorithms. Mobile robots are non - linear systems so that their optimal control gains depend on initial positions. Hence initial positions are divided into some partition points and optimal control gains are obtained at each partition point with genetical algorithms. These optimal control gains are used to train neural networks that generate proper control gains at arbitrary initial position. Finally computer simulation studies have been conducted to verify the effectiveness of the method proposed in this paper.

• Korean Journal of Clinical Pharmacy
• /
• v.24 no.2
• /
• pp.98-105
• /
• 2014

Purpose: The aim of this study was to compare retrospectively the efficacy of anti-osteoporotic agents (RAL-Raloxifene 60 mg, ALD-weekly alendronate 70 mg, RSD-weekly risedronate 35 mg, AVD3-weekly alendronate 70 mg/vitamin $D_3$ 2800IU, IBD-quarterly IV ibandronate 3 mg/3 ml, ZLD-yearly IV zoledronate 5 mg/100 ml) in postmenopausal patients with osteoporosis or osteopenia. Method: This study retrospectively reviewed medical record and compared the lumbar spine BMD percentage changes of each medicine group one year later from the baseline. 209 patients (27, 50, 60, 30, 35, and 7 patients in RAL, ALD, RSD, AVD3, IBD, and ZLD groups, respectively) are within the inclusion criteria for the study. Results: From baseline to month 12, lumbar spine BMD increased significantly larger with bisphosphonate groups, compared to SERM (p < 0.05). In all bisphosphonate groups, the lumbar spine BMD were increased significantly from baseline. Of the bisphosphonates, the changes from baseline in BMD of IV bisphosphonates were more larger than those of oral bisphosphonates, and yearly, quarterly bisphosphonates yielded significantly greater BMD gains, compared with weekly bisphosphonate groups (p<0.05). In addition, patients receiving 70 mg weekly alendronate+vitamin D3 had greater gains in BMD than alendronate Single preparation (p<0.05). Conclusion: Bisphosphonates yielded significantly greater BMD gains than SERM. Of the bisphosphonates, the changes from baseline in BMD of yearly, quarterly IV bisphosphonates yielded significantly greater BMD gains, compared with weekly oral bisphosphonate groups. In addition, vitamin D3 plays an significant role in BMD gains.

• Journal of the Society of Naval Architects of Korea
• /
• v.54 no.2
• /
• pp.102-112
• /
• 2017

Many studies on dynamic positioning control algorithms using fixed feedback gains have been carried out to improve station keeping performance of dynamically positioned vessels. However, the control algorithms have disadvantages in that it can not cope with changes in environmental disturbances and response characteristics of vessels motion in real time. In this paper, the Fuzzy Gain Scheduling - PID(FGS - PID) control algorithm that can tune PID gains in real time was proposed. The FGS - PID controller that consists of fuzzy system and a PID controller uses weighted values of PID gains from fuzzy system and fixed PID gains from Ziegler - Nichols method to tune final PID gains in real time. Firstly, FGS - PID controller, control allocation algorithm, FPSO and environmental disturbances were modeled using Matlab/Simulink to evaluate station keeping performance of the proposed control algorithm. In addition, simulations that keep positions and a heading angle of vessel with wind, wave, current disturbances were carried out. From simulation results, the FGS - PID controller was confirmed to have better performances of keeping positions and a heading angle and consuming power than those of the PID controller. As a consequence, the proposed FGS - PID controller in this paper was validated to have more effectiveness to keep position and heading angle than that of PID controller.

• Korean Journal of Veterinary Research
• /
• v.12 no.1
• /
• pp.1-5
• /
• 1972

In oder to investigate the effects of cobalt-60 gamma ray irradiation on the body gains of rabbits aging approximately 50-day-old rabbits were subjected to single whole-body gamma irradiation externally. The results obtained were as follows: 1. There were significant differences of the body gains between control and treated groups except the 100 rads gamma-rays exposure group. 2. There were no differences in body gains between male and female rabbits. 3. Generally, the relation between gamma irradiated doses and the growth rates of rabbits were inversly proportional. 4. The $LD_{50}$ of the rabbits was 600 rads in case of single external whole-body gamma irradiation.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.21 no.9
• /
• pp.1462-1469
• /
• 1997

This study presents a genetic algorithm-based method for optimizing control parameters in fluid power systems. Genetic algorithms are general-purpose optimization methods based on natural evolution and genetics. A genetic algorithm seeks control parameters maximizing a measure that evaluates system performance. Five control gains of the PID-PD cascade controller fr an electrohydraulic speed control system with a variable displacement hydraulic motor are optimized using a genetic algorithm in the experiment. Optimized gains are confirmed by inspecting the fitness distribution which represents system performance in gain spaces. It is shown that optimization of the five gains by manual tuning should be a task of great difficulty and that a genetic algorithm is an efficient scheme giving economy of time and in labor in optimizing control parameters of fluid power systems.

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.4
• /
• pp.259-269
• /
• 2003

This paper considers the problem of determining a set of PI, PD and PID controller gains, for a given linear time invariant plant, that meets or exceeds the closed loop step response specifications. The proposed method utilizes two recent results: for a given system, (1) finding a set of stabilizing PI, PD and PID gains and (2) the relationship between time response (overshoot and speed) and the coefficients of the characteristic polynomial. The method allows us to extract a subset of PI, PD and PID gains that meets stability as well as time domain performance requirements. The intersections of two dimensional sets described by linear and quadratic inequalities in the controller design space are need to be Identified through numerical computation. The procedure is illustrated by examples.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1-6
• /
• 2003

This paper considers the problem of determining a set of stabilizing first order controller gains, for a given linear time invariant plant, that meets or exceeds closed loop step response specifications. The method utilizes two recent results: For a given system, (1) finding a set of stabilizing first order controller gains and (2) the relationship between time response (overshoot and speed) and the coefficients of the characteristic polynomial. The method allows us to extract a subset of first order controller gains that meets stability as well as time domain performance requirements. The computations involved are the intersections of two dimensional sets described by linear and quadratic inequalities in the controller design space. It is illustrated by examples.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.2
• /
• pp.139-145
• /
• 2014

Periodic disturbance compensators are widely used in track following servo systems. They are commonly designed and implemented by adaptive feedforward compensators or internal model based compensators. In track following servo systems, the gains of the compensators should be determined considering the change of the sensitivity transfer function and the implementation methods should be selected considering the system environment. This paper proposes a guide for determining gains of the periodic disturbance compensators. Various simulation and experimental results are presented to see the effect of gains. In addition, this paper introduces the various types of implementation methods and compares their merits and demerits.

• Journal of the Korean Society for Precision Engineering
• /
• v.29 no.1
• /
• pp.79-86
• /
• 2012

This paper proposes PID and RIC (Robust Internal-loop Compensator) based motion controller using dual learning algorithm for position control of linear synchronous motor respectively. Its gains are auto-tuned by using two learning algorithms, reinforcement learning and neural network. The feedback controller gains are tuned by reinforcement learning, and then the feedforward controller gains are tuned by neural network. Experiments prove the validity of dual learning algorithm. The RIC controller has better performance than does the PID-feedforward controller in reducing tracking error and disturbance rejection. Neural network shows its ability to decrease tracking error and to reject disturbance in the stop range of the target position and home.