• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2395-2406
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• 2023

To study the influence of parameter uncertainty in small pressurized water reactor (SPWR) once-through steam generator (OTSG), the nonlinear mathematical model of the SPWR is firstly established. Including the reactor core model, the OTSG model and the pressurizer model. Secondly, a control strategy that both the reactor core coolant average temperature and the secondary-side outlet pressure of the OTSG are constant is adopted. Then, the uncertainty quantification method is established based on Latin hypercube sampling and statistical method. On this basis, the quantitative platform for parameter uncertainty of the OTSG is developed. Finally, taking the uncertainty in primary-side flowrate of the OTSG as an example, the platform application work is carried out under the variable load in SPWR and step disturbance of secondary-side flowrate of the OTSG. The results show that the maximum uncertainty in the critical output parameters is acceptable for SPWR.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.295-300
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• 2005

The freeplay, one of the concentrated structural nonlinearities, is inevitable for control surfaces of a real air vehicle due to normal wear of components and manufacturing mismatches. Also aerodynamic nonlinearities caused by a shock wave occur in transonic region. In practice, these nonlinearities induce the limit cycle oscillation (LCO) and decrease the transonic flutter speed. In this study, the fictitious mass method is used to apply a modal approach to nonlinear structural models due to freeplay. The transonic small-disturbance (TSD) equation is used to calculate unsteady aerodynamic forces in transonic region. Nonlinear aeroelastic time responses are predicted by the coupled time integration method (CTIM). This method was also applied to a 3D all-movable control wing to investigate its nonlinear aeroelastic responses. The angle of attack effect on the LCO characteristics has been found to be closely related with the initial pitching moment.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.8
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• pp.367-375
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• 2001

In Underwater Flight Vehicle depth control system, the followings must be required. First, it needs robust performance which can get over modeling error, parameter variation and disturbance. Second, it needs accurate performance which have small overshoot phenomenon and steady state error to avoid colliding with ground surface or obstacles. Third, it needs continuous control input to reduce the acoustic noise and propulsion energy consumption. Finally, it needs interpolation method which can sole the speed dependency problem of controller parameters. To solve these problems, we propose a depth control method using Fuzzy Sliding Mode Controller with feedforward control-plane bias term and Neural Network Interpolator. Simulation results show the proposed method has robust and accurate control performance by the continuous control input and has no speed dependency problem.

• International Journal of Railway
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• v.4 no.1
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• pp.19-27
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• 2011

Many studies for improving the railway vehicle's performance and comfort such as speed, weight and noise are currently in progress. Improving the structural characteristics of the vehicle for greater noise insulation is considered important for reducing disturbance due to noise, but measuring transmission loss entails large costs. This study explores an alternative method for estimating and measuring the railway vehicle's transmission loss that involves on applying the numerical analysis coupled with scaled reverberation chamber measurement. The transmission loss measurement using scaled reverberation chamber was performed after the compensation value was found through 1mm thickness(1t) specimen. For numerical analysis, a commercially available acoustics solver VA ONE was used. The proposed method is found to lead to transmission loss measurement comparable to the measurements based on large-scale reverberation chamber. Thus, it can be argued that a reliable method has been developed for measuring railway vehicle's transmission loss.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.35-42
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• 2000

The sway control problem of the pendulum motion of a container hanging on the trolly, which transports containers from a container ship to trucks, is considered in the paper. In the container crane control problem, suppressing the residual swing motion of the container at the end of acceleration or the case of that the unexpected disturbance input exists is main issue. For this problem, in general, the trolley motion control strategy is introduced and applied. But in this paper, we introduce and synthesize a new type of swing motion control system. In this control system, a small auxiliary mass is installed on the spreader. And the actuator reacts against the auxiliary mass, applying intertial control forces to the container to reduce the swing motion in the desired manner. In this paper, we apply the LMI approach and simultaneous optimization design method to design the anti-swing motion control system for the controlled plant. And the simulation result shows that the proposed control strategy is shown to be robust to disturbances like winds and initial sway motion.

• The Journal of Internal Korean Medicine
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• v.15 no.2
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• pp.383-417
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• 1994

By making use of the EAV(Electroacupuncture acc. Voll) combined meridian theory of oriental medicine with electronics which was contrived to recognize the physiological and pathological changes of human body, the following conclusions were made in comparison with EAV measurements and types of symptoms(anxiety & headache, fatigue, palpitation, dizzness, abdominal distension. nausea, gastric disturbance. constipation & diarrhea, fatty liver, cva), QSCC, and blood type test. 367 patients including 124 with nervous gastrointestinal problems were selected for this research. 1. From the point of variance of the tested patients 124 nervous gastrointestinal patients, Liver meridian and Spleen meridian showed hyperenergia and Large intestine meridian, Circulation meridian, Triple warmer meridian showed hypoergia 2. In each symptom as the nervous gastrointestinal symptom Liver meridian showed hyperenergia, Large intestine meridian, Circulation meridian and Triple warmer meridian showed hypoergia . 3. In an objective comparison with other symptoms, firstly among the headache & anxiety group left Gall Bladder, Triple warmer and Stomach meridian showed remarkable hypoergia, secondly among fatigue group showed hypoergia in Triple warmer meidian and hyperenergia of Stomach meridian. and thirdly among palpitation group showed hypoergia of Kidney meridian, and lastly among dizzness group showed hypoergia of Gall Bladder, Stomach, Circulation and Small intestine meridian. 4. All of gastric disturbance, nausea, abdominal distention, constipation and diarrhea group showed hyperenergia in Stomach meridian and Spleen meridian. gastric disturbance group showed remarkably hypoergia in Circulation. Small intestine, Lung and Large intestine meridian. Nausea group showed hypoergia in Gall bladder and Urinary bladder meridian. Abdominal distenton group showed hypoergia of Large intestine. Constipation and diarrhea group showed hypoergia of Kidney and left Circulation meridian. 5. Fatty liver group showed hyperenergia of Liver meridian of 83.3%, Gall Bladder, Stomach and Spleen meridian. Urinary bladder and Kidney meridian showed hypoergia 6. CVA group showed hyperenergia in Liver and Circulation meridian. 7. Blood type in typical classification had no significant bearings on each other. 8. QSCC for the attempt of objective materials of constitutional diagnosis had no correlativity in comparison with EAV measurements. In conclusion EAV is thought be used as a diagnostic method in oriental medicine and further research is needed regarding it can be used as a useful method for verifying the characteristics and early finding of symptoms.

• Journal of Aerospace System Engineering
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• v.17 no.5
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• pp.34-41
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• 2023

This paper applies the icing effect and wing rock uncertainty to small unmanned aerial vehicles (UAVs), which have recently attracted attention. Attitude control simulations were performed using various control methods. First, the selected platform, the Skywalker X8 UAV with blended wing-body (BWB) configuration, was linearized for both its baseline form, and a form with applied icing effects. Subsequently, using MATLAB SimulinkⓇ, simulations were conducted for roll and pitch attitude control of the baseline configuration and the configuration with icing effects, employing disturbance observer-based PID control, model reference adaptive control, and model predictive control. Furthermore, the study introduced wing rock uncertainty simultaneously with icing effects on the configured model-a combination not previously explored in existing research-and conducted simulations. The performance of each control Method was compared and analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1973-1980
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• 2017

In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.2
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• pp.301-308
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• 2017

This paper proposes a disturbance observer based controller design method for generating and yawing control of windturbine with two cooperative generators. Windturbine system with two cooperative generators is a distinct structure in which the wind energy supplied by blade axis is converted into electrical energy by two cooperative generators. In this structure, two generators can be controlled independently and therefore they can generate power, simultaneously performing yawing control of nacelle without extra yawing mechanism by cooperatively controlling generating load in appropriate manner. Using this structural trait, this paper designs a disturbance observer based controller that enables the windturbine system with cooperative generators to generate and yaw stably, and verifies the performance of the controller experimentally by applying it to a small-scale windturbine system with the same structure.

• Proceedings of the KIEE Conference
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• 2008.04a
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• pp.232-233
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• 2008

There are various large shocks in optical disc drive system like human touch and speak sound. In this paper, a nonlinear controller and a detection method are proposed. First, a relay nonlinear controller with dead zone is introduced. The structure of this nonlinear controller is simple and has a small amount of calculation. However, this controller has chattering problem when it is working. We suggest a disturbance detection algorithm using Kalman filter in this paper and it shows effective reduction of chattering. The proposed nonlinear controller using this detection algorithm had good performance for the shock.