• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.171.3-171
• /
• 2001

The master/slave-combined system has a simplified and miniaturized structure formed by combining the master and slave that are the teleoperation system. In a certain situation, the operator may want to feel the magnified/reduced admittance of the real environments. Or he may want to feel the specific predefined admittance of the virtual environments. This paper presents a force feedback control structure for the master/slave-combined system. Through the proposed control structure, the operator can feel the predefined admittance of the virtual environments in case of free motion, and the magnified/reduced admittance of real environments in case of contact situation. It is discussed how the elements of the admittance effect ...

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.1108-1112
• /
• 2005

Recently, the fuel charge is accounted for very high in the navigation cost. Therefore Shipowner is tried to find method for reducing oil consumption. ERCS(Energy Reduced Cooling System) is one of the method. The ERCS algorithm operates to decrease a power consumption of main sea water cooling pump through inverter control. We have developed ERCS controller with algorithm. The ERCS controller consists of CPU board, Digital I/O board, A/D board, D/A board and LCD/SW board. We tested with dummy signal to confirm the algorithm working correctly and achieved the good results. Before soon we will test under real condition in the ship and expect to get the result as forecasted.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1999.11a
• /
• pp.184-189
• /
• 1999

This Paper presents the friction and lubrication charateristic related with oil aeration. It is well known that oil aeration occurs severe problem on lubrication system, in particular, in the engine bearings and hydraulic lash adjuster. In this study, engine tests were carried out in motoring conditions. In order to investigate oil aeration characteristics, we measured oil aeration with respect to oil temperature, oil viscosity, modified oil drain system. From the results, we concluded that aeration can be reduced by improving oil drain system and FMEP can be reduced by minimising of aeration.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.5
• /
• pp.541-549
• /
• 2007

In the case of control for mechanical systems, it is highly useful to be able to provide a compact model of the mechanical system to control engineers using the smallest number of state variables, while still providing an accurate model. The reduced mechanical model can then be inserted into the complete system models and used for extended system-level dynamic simulation. In this paper, moment-matching based model order reductions (MOR) using Krylov subspaces, which reduce the number of degrees of freedom of an original finite element model via the Arnoldi process, are presented to study the eigenvalue and frequency response problems of a HDD actuator and suspension system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.871-874
• /
• 2002

Many malfunctions take place in container crane spreader due to impact. So we designed a 2DOF hydraulic impact absorbing system with multi-step damping coefficient and studied the effect of orifice's interval and damping coefficient. The damping coefficient of upper piston was found to be 180 N.s/m, and the orifice's interval to be 9mm, the max reaction force and the average reaction force might be lowest. Compared with a general 2-DOF impact absorbing system, the max reaction force reduced by 46%., and average reaction force reduced by 5%.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.8
• /
• pp.509-513
• /
• 2000

This paper deals with the parallel operation of space vector PWM for large capacity inverter system. To enlarge the capacity of inverter system and to reduce the current ripples on inverter output side, two or more inverters are operated in parallel. In this paper, a new parallel operation strategy which minimizes the harmonic distortion of the output stage is described. The proposed method is developed on the basis of the space-vector PWM in order to increase the linearly controllable voltage range. With the help of the proposed voltage synthesis method, the total harmonic distortion of the output stage can be greatly reduced in compared with that of conventional method with sinusoidal PWM or that of the single inverter operation case. The experimental results with reduced scale test show the feasibility of the proposed voltage synthesis method.

• Current Optics and Photonics
• /
• v.5 no.6
• /
• pp.627-640
• /
• 2021

In a free-space coherent optical communication system, wavefront distortion is frequently beyond the correction range of the adaptive-optics system after the laser has propagated through the atmospheric turbulence. A method of residual wavefront correction is proposed, to improve the quality of coherent optical communication in free space. The relationship between the wavefront phase expanded by Zernike polynomials and the mixing efficiency is derived analytically. The influence of Zernike-polynomial distortion on the bit-error rate (BER) of a phase-modulation system is analyzed. From the theoretical analysis, the BER of the system changes periodically, due to the periodic extension of wavefront distortion. Experimental results show that the BER after correction is reduced from 10^-1 to 10^-4; however, when the closed-loop control algorithm with residual correction is used, the experimental results show that the BER is reduced from 10^-1 to 10^-7.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1997.06a
• /
• pp.143-158
• /
• 1997

Electrochemical deionization (EDI) offers continuous demineralization at higher water recovery rates (>90%), compared with mixed bed ion exchange, and without the use of chemical regenerants and the associated production of saline waste water. Although EDI technology has been used in some power generation applications, its wider application requires the satisfactory resolution of outstanding capital cost and performance issues. This paper reports on the field evaluation of a new cost-effective EDI technology in a power generation application. The E-Cell System$^{TM}$, which became commercially available in the fourth quarter of 1996, consists of a rugged, modular system, based on a new high-performance EDI stack. Starting in May 1996, a 100 gpm modular EDI pilot system, rated for operation at 100 psi, was evaluated at the TVA Brown's Ferry Nuclear Plant. The feed consisted of Reverse Osmosis (RO) permeate with a conductivity of 4-7 $\mu$S/cm. The pilot system reliably produced 17.8-18.0 M$\Omega$.cm water under design operating conditions, independent. Silica levels were reduced from ca. 50 ppb to 4 ppb, while TOC levels were reduced from ca. 120 ppb to 30 ppb.

• Journal of Advanced Navigation Technology
• /
• v.16 no.6
• /
• pp.1123-1133
• /
• 2012

This study configuration Vector Control System which is stable and has outstanding Dynamic Characteristics in Very Low Speed Region and Low Speed Region, and proposes Instantaneous Speed Observer and Very Low Speed Control method and vector control system of the speed estimation a using Reduced-Dimensional State Observer. The Observer proposed in this system, by appling Reduced-Dimensional State Observer to Load-Torque estimation and using for speed estimation, implements system composition simply and is capable of accurate Instantaneous Speed estimation in Very Low Speed Region. Also, this study reduces influence by System Noise and suggests an induction motor speed control system which is effective in Load Disturbance, modeling error, estimation noise and so on without changing pole of an Observer.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.1
• /
• pp.26-33
• /
• 2013

Femto-cells are low power/cost, micro-base stations and are main components in heterogeneous networks. However, some of technical issues arise when femto-cells are initially installed. One approach to resolve the problems is to control the transmission (TX) power autonomously via SON(Self-Organized Network) scheme. By controlling the femto-cell TX power, the system throughput performance can be improved or the system overhead is highly reduced. Generally, the TX power for maximizing the system throughput and that for reduced system overhead may not be identical. Therefore, we propose a TX power control scheme by which we can improve the system throughput and reduce the system overhead, simultaneously. When we apply the proposed method, the simulation results show that the system overhead can be reduced by up to 41% compared to the performance of the method which maximizes throughput performance only, and the throughput performance can be improved by up to 63% compared to that of the method which only optimizes the coverage area.