• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.21 no.1
• /
• pp.165-173
• /
• 2023

Various linear system solvers with multi-physics analysis schemes are compared focusing on the near-field region considering thermal-hydraulic-chemical (THC) coupled multi-physics phenomena. APro, developed at KAERI for total system performance assessment (TSPA), performs a finite element analysis with COMSOL, for which the various combinations of linear system solvers and multi-physics analysis schemes should to be compared. The KBS-3 type disposal system proposed by Sweden is set as the target system and the near-field region, which accounts for most of the computational burden is considered. For comparison of numerical analysis methods, the computing time and memory requirement are the main concerns and thus the simulation time is set up to one year. With a single deposition hole problem, PARDISO and GMRES-SSOR are selected as representative direct and iterative solvers respectively. The performance of representative linear system solvers is then examined through a problem with an increasing number of deposition holes and the GMRES-SSOR solver with a segregated scheme shows the best performance with respect to the computing time and memory requirement. The results of the comparative analysis are expected to provide a good guideline to choose better numerical analysis methods for TSPA.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.200-202
• /
• 2003

In this paper, Gauss filter function is used to filter the N-S equation and the subgrid-scale Reynold stresses model is introduced to deduce the practical form of LES equation for 2-D case for flow calculation of hydraulic machine. Then the LES equation and its discrete form in computational field are obtained in the body-fitted coordinate system and the numerical calculation program is built. The incompressible turbulent flow in double-flow-conduits-sewage pump impeller is computed by using the abovementioned program, and then the distribution rules of velocity and pressure in flow field are obtained. Based on this, the designs of double-flow-conduits-sewage pump impeller are optimized.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.409-411
• /
• 1996

The purpose of this paper is construction of PMS with extension of consuming time of battery in the special vehicle system using exact Battery state of charge measurement algorithm. It is possible to use long distance control by RS-485, fast data processing VMEbus. Its computer simulation, experimental tests and application to special vehicle are described.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.11
• /
• pp.122-132
• /
• 1999

This study describes a dynamic model of the hydroforming process which is used for precision forming of sheet metals. To help the controller design for the control of the forming pressure needed for this process as well as to investigate the effect of system parameters on the dynamic behavior, dynamic modeling is performed with emphasis on hydraulic servo system which actuates the forming machine. Since the model contains several unknown parameters, these were estimated via a least square parameter identification method. Based upon the identified model, a series of simulations were performed for various operating conditions. The results were compared with those of the experiments to verify the validity of the proposed model. The comparison study shows that the proposed dynamic model can describe dynamic behavior of the forming pressure of the hydroforming process to desirable accuracy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1998.04a
• /
• pp.608-613
• /
• 1998

Damping characteristics of ER dampers and flow rates inside ER valve with two different valve types were analyzed and compared with test results. Fluid flow inside ER valves was modeled by Bingham plastic model and Hagen-Poiseulli flow, while the equations of motion of total ER damper system were modeled by flow and hydraulic force balance. A general straight valve case was compared with a bended valve case which is newly tested for a possible improvement of ER damping force. As expected, the bended ER valve generates higher damping force and lower flow rates than the conventional straight ER valve due to additional flow restriction at the bended section. Analytical models of ER valve and ER damper generally predict reasonable performance characteristics of tested results. Therefore, developed analysis can be used for designing new ER dampers and simulation of ER semi-active suspension system as well.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.31 no.3
• /
• pp.35-46
• /
• 1999

Mathematical modeling provided a systematic analysis for the dynamic behavior of stock fluid in a paper machine pressurized headbox. Dynamic responses of liquid level, sheet basis weight and hydraulic pressure were predicted from the simulation model which represents the system. A unit step and asinusoidal wave load were considered as the input forcing functions in the headbox. Results are summarized as follows : 1. The dependence of sheet basis weight on liquid level in the pressurized-headbox was non -linear. 2. Liquid level in the head-box showed first-order lag with a unit step forcing to fluid input rate ; 3 . The amplitude of wave response of liquid level was inversely proportional to the time content for the sinusoidal input changes ; 4.Sheet basis weight showed second-order oscillating underamped responses for the step input load of flow rate ; 5. The damping factor in the second-order system was a function of air-pressure in the headbox ; and, 6. Dead-time existed in the measuring process for the headbox slice pressure.

• Proceedings of the KIEE Conference
• /
• 2007.04c
• /
• pp.119-121
• /
• 2007

The increment of electric power demand causes interest on new higher power system such as 42V Power Net, and furthermore necessity for development of energy storage device is highlighted recently. Owing to high efficiency and easy speed control of brushless DC(BLDC) motor, the demand of BLDC motor that has high power and low noises are increasing. Especially demand of interior permanent magnet(IPM) type BLDC with high efficiency and high power in electric motion vehicle is increasing. This paper presents the design of the BLBC motor for EHPS(Electro-Hydraulic Power Steering) in 42V system and verified the characteristics by simulation and test results.

• Journal of Biosystems Engineering
• /
• v.14 no.2
• /
• pp.85-93
• /
• 1989

This study was intended to develop the system which controls header height of combine automatically by means of sensing the difference between the header and the ground surface. A micro-computer was used for the controller. The sensing unit designed for the study was composed of potentiometer, oscillating link, and gage wheel. An electric-hydraulic circuit was driven by microcomputer to control header height of combine. Performance of the control system was tested by computer simulation, stationary operation of header, and traveling on the simulated ground.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.151-155
• /
• 1996

To automate an excavator the control issues resulting from environmental uncertainties must be solved. In particular the interactions between the excavation tool and the excavation environment are dynamic, unstructured and complex. In addition, operating modes of an excavator depend on working conditions, which makes it difficult to derive the exact mathematical model of excavator. Even after the exact mathematical model is established, it is difficult to design of a controller because the system equations are highly nonlinear and the state variable are coupled. The objective of this study is to design a multi-layer neural network which controls the position of excavator's attachment. In this paper, a dynamic controller has been developed based on an error back-propagation(BP) neural network. Computer simulation results demonstrate such powerful characteristics of the proposed controller as adaptation to changing environment, robustness to disturbance and performance improvement with the on-line learning in the position control of excavator attachment.

• Proceedings of the KIEE Conference
• /
• 1998.07b
• /
• pp.452-454
• /
• 1998

Asymmetric cylinders are usually used as an actuator of active suspensions. The conventional optimal controller design does not include actuator dynamics as a state. and force controller is needed to track the desired force. But the actuator is not ideal, so performance of an active suspension system is degraded. In this paper, we take account nonlinear actuator dynamics and obtain a linear model using a feedback linearization technique then apply optimal control method. For real time application, gain-scheduling method is used. Effectiveness of proposed method is demonstrated by numerical simulation of 1/4 car model.