• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.4
• /
• pp.71-78
• /
• 2007

Input shaping is known to be a very effective tool for suppressing residual vibration without introducing any complicated sensors and feedback control. Real-time input shaping schemes necessitate a process such that the input command is discretized to deal with non-prescribed, real-time input. Thus parameters associated with input command discretization, such as time spacing and duration time, are unknowns which affect the performance of input shaping schemes, especially for small and fast XY stages. This paper investigates the effects of input command discretization parameters, such as time spacing and duration time, on the dynamic performance of XY stages subjected to real-time input shaping. An experimental system is developed which is equipped with an XY stage driven by servo-motors and real-time user command. Experiments are performed to investigate the dynamic performance of XY stage by changing these parameters and to yield a strategy to gain better performance.

• Nuclear Engineering and Technology
• /
• v.55 no.8
• /
• pp.2757-2772
• /
• 2023

The fluid retention effect of the Volume Control Tank (VCT) leads to a long time delay in Reactor Coolant System (RCS) concentration during the boration process. A coupled model combining a lumped-parameter sub-model and a computational fluid dynamics sub-model is currently used to investigate the concentration dynamic characteristic of RCS during the boration process. This model is validated by comparison with experimental data, and the predicted results show excellent agreement with experimental data. We provide detailed fields in VCT and concentration variations of RCS to study the interaction between mixing in VCT and the transient responses of RCS. Moreover, the impacts of the inlet flow rate, inlet nozzle diameter, original concentration, and replenishing temperature of VCT on the RCS concentration characteristic are studied. The inlet flow rate and nozzle diameter of VCT remarkably affect the RCS concentration characteristic. Too-large or too-small inlet flow rates and nozzle diameters will lead to unacceptable long delays. In this work, the optimal inlet flow rate and nozzle diameter of VCT are 5 m³/h and 58.8 mm, respectively. Besides, the impacts of the original concentration and replenishing temperature of VCT are negligible under normal operating conditions.

• IE interfaces
• /
• v.20 no.4
• /
• pp.504-514
• /
• 2007

The multicast routing problem lies in the composition of a multicast routing tree including a source node and multiple destinations. There is a trade-off relationship between cost and delay, and the multicast routing problem of optimizing these two conditions at the same time is a difficult problem to solve and it belongs to a multi-objective optimization problem (MOOP). A multi-objective genetic algorithm (MOGA) is efficient to solve MOOP. A micro-genetic algorithm(${\mu}GA$) is a genetic algorithm with a very small population and a reinitialization process, and it is faster than a simple genetic algorithm (SGA). We propose a multi-objective micro-genetic algorithm (MO${\mu}GA$) that combines a MOGA and a ${\mu}GA$ to find optimal solutions (Pareto optimal solutions) of multicast routing problems. Computational results of a MO${\mu}GA$ show fast convergence and give better solutions for the same amount of computation than a MOGA.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.2651-2654
• /
• 2000

In this paper, we re-analyzed the fuzzy controller as conventional PID controller structure, and proposed a self tuning fuzzy PID controller whose input output scaling factors were tuned automatically. At first stage, the tuning parameters of fuzzy controller were determined by Ziegler-Nichols tuning method and then they were adjusted as the delay time and process environment were changed. Proposed controller was simple in its structrue and computational burden was small so that on line adaptation was easy to apply to. The result of computer simulation and practical experiment showed the proposed controller's excellent performance

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.2
• /
• pp.122-133
• /
• 2013

An arbiter-based simple phase decision circuit (PDC) optimized for high-resolution phase-to-digital converter made up of an analog phase-frequency detector and a time-to-digital converter for all-digital phase-locked loops is proposed. It can distinguish very small phase difference between two pulses even though it consumes lower power and has smaller input-to-output delay than the previously reported PDC. Proposed PDC is realized using 130-nm CMOS process and demonstrated by transistor-level simulations. A 5-bit P2D having no offset nor deadzone using the PDC is also demonstrated. A harmonic-lock-free and small-phase-offset delay-locked loop for fixing the P2D resolution regardless of PVT variations is also proposed and demonstrated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.8
• /
• pp.526-533
• /
• 2008

In this study, theoretical super screen vibration analysis has been carried out to predict the dynamic characteristics of interactive waste particles. In order to approach these problems, it is necessary to have a fundamental understanding the screening process and the process of both the remaining and the passed material on a screen with several interacting screen planes based on Soldinger(1999) was discussed. Here, the vibrating screen is composed of three assemblies such as screen, wastes guide, and supported screen as shown in Fig. 1. This model is regarded vibrator as the system of screen fixed tilt plates. Then materials(or particles) of different size is to be separated by using the eccentric vibrator and classifying tilt plates. As well moisturized construction wastes is more efficient to separate than moisture-less it. In processing separate mechanism, the more materials is light, the more staying time is long. Thus much lighter construction wastes(wood, Styrofoam, etc) and heavier materials are separated by staying time delay in a super screen. The design results, separation screen were able to know that small and larger particles are conspicuous difference each motion character according to trajectory particles, and small particles raise the probability in classifying tilt plates.

• Korean Journal of Remote Sensing
• /
• v.33 no.4
• /
• pp.391-400
• /
• 2017

Geo-based application services linked with the Open Geospatial Consortium (OGC) Web Processing Service (WPS) protocol have been regarded as an important standardized framework for of digital earth building in the web environments. The WPS protocol provides interface standards for analysis functionalities within geo-spatial processing in web-based service systems. Despite its significance, there is few performance tests of WPS applications. The main motivation in this study is to perform the comparative performance test on WPS standards. Test system, which was composed of WPS servers, WPS framework, data management module, geo-based data processing module and client-sided system, was implemented by fully open source stack. In this system, two kinds of geo-based image processing functions such as cloud detection and gradient magnitude computation were applied. The performance test of different server environments of non-WPS, synchronous WPS 1.0 and asynchronous WPS 2.0 was carried out using 100 threads and 400 threads corresponds client users on a web-based application service. As the result, at 100 threads, performance of three environments was within an adjacent range in the average response time to complete the processing of each thread. At 400 threads, the application case of WPS 2.0 showed the distinguished characteristics for higher performance in the response time than the small threads cases. It is thought that WPS 2.0 contributes to settlement of without performance problems such as time delay or thread accumulation.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.45 no.8
• /
• pp.32-36
• /
• 2008

Multiplierless FIR filters can be designed by only adders using Common Subexpression algorithm. It has small area compared with filter which using multipliers. But it has long operation time because of carry ripple from the adder. In this paper, when the subexpressions are added in multiplier less filters, the number of subexpressions maintains 2 until final addition to avoid carry ripple of the addition, so the subexpression addition time of the filter can be reduced. To verify proposed method, subexpression adder circuit of the FIR filter is designed using given example of paper. The designed filter was synthesized using Hynix 0.18um process. By Synopsys simulation results, it is shown that by the proposed method, area, propagation delay time can be reduced up to 53.2%, 57.9% compared with conventional design method which using pipeline.

• Explosives and Blasting
• /
• v.31 no.2
• /
• pp.14-24
• /
• 2013

The most effective way of the rock removing works in the downtown area is to removing rocks by splitting the rock by blasting with small amount of explosives in the hole. However environmental factors not only limit the applications but also increase the forbidden area. As this is a distributed multi-stage blasting method and to reduce vibration by applying the optimized precisioncontrol-blasting method, it is applicable in all situations. The process is to fix the stemming-help plastic sheet to the hole entrance when stemming explosives and insert detonator and explosive primer with same delay time, two or three sets. This method is more efficient in the downtown area where claims and dispute from vibration are expected. This method is easily usable by designing blast pattern even in the area where delay time blasting is difficult after multi-stage explosive stemming due to short length of blast hole (1.2~3.0m) and there is no detonator wire shortage or dead-pressure.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.12 s.177
• /
• pp.51-60
• /
• 2005

This paper describes a robust control scheme for high-speed and long stroke scanning motion of high precision linear motor system consisting of linear motor, air bearing guide and position measurement system using heterodyne interferometer. Nowadays, semiconductor process and inspection of wafer or LCD need high speed and long travel length for their high throughput and extremely small velocity fluctuations or tracking errors. In order to satisfy these conditions, linear motor system are widely used because they have large thrust force and do not need motion conversion mechanisms such as ball screw, rack & pinion or capstan with which the system are burdened. However linear motors have a problem called force ripple. Force ripple deteriorates the tracking performances and makes periodic position errors. So, force ripple must be compensated. To maximize the tracking performance of linear motor system, we propose the control scheme which is composed of a robust control method, Time Delay Controller (TDC) and a feedforward control method, Zero Phase Error Tracking Control (ZPETC) for accurate tracking a given trajectory and an adaptive force ripple compensation (AFC) algorithm fur estimating and compensating force ripple. The adaptive ripple compensation is continuously refined on the basis of tracking error. Computer simulation results based on modeled parameters verify the effectiveness of the proposed control scheme for high-speed, long stroke and high precision scanning motion and show that the proposed control scheme can achieve a sup error tracking performance in comparison to conventional TDC control.