• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.371-376
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• 2003

In general, the electronic forklift driven by DC motor drive system is used in the industrial field. Classically, the DC motor is controlled by speed control using proportion control method, by output torque following the load on the plane like a manual operation. But in the industrial field, the electronic forklift is demanded the robust drive mode. Some cases of the mode, there are trouble in torque and speed control following slope capacity. The control is sensitive concerning with slope angle and output speed, various control method is studied for stability of speed control. We apply speed controller for the self-tuning using DSP(TMS320F240) as main controller for high speed processor, embody dynamic characteristic of control compared the PI control to the fuzzy control.

• Journal of KSNVE
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• v.8 no.6
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• pp.1030-1036
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• 1998

When the lateral dimensions of a duct is larger than or comparable to the wavelengths of Interest, higher order modes propagate in the duct. These modes will be radiated and produce noise. A number of sensors and actuators for control of radiating noise from the duct have to be incorporated with the number of modes which one wants to control. These considerations motivated the present study that considers a control system which has less microphones and control sources than required. In this work, by theoretical analysis, the control performance of such a kind of system is investigated in terms of sound-field variables and control system variables. The possible maximum and minimum value. mean and variance of residual acoustic potential energy are derived for the set of primary sound fields.

• Geomechanics and Engineering
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• v.11 no.5
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• pp.607-624
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• 2016

Rockburst is becoming more serious in Chinese coal mine. One of the effective methods to control rockburst is blasting. In the paper, we monitored and analyzed the blasting waves at different blast center distances by the Hilbert-Huang transform (HHT) in a coal mine. Results show that with the increase of blast center distance, the main frequency and amplitude of blasting waves show the decreasing trend. The attenuation of blasting waves is slower in the near blast field (10-75 m), compared with the far blast field (75-230 m). Besides, the frequency superposition phenomenon aggravates in the far field. A majority of the blasting waves energy at different blast center distances is concentrated around the IMF components 1-3. The instantaneous energy peak shows attenuation trend with the blast center distance increase, there are two obvious energy peaks in the near blast field (10-75 m), the energy spectrum appears "fat", and the total energy is greater. By contrast, there is only an energy peak in the far blast field, the energy spectrum is "thin", and the total energy is lesser. The HHT three dimensional spectrum shows that the wave energy accumulates in the time and frequency with the increasing of blast center distance.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.216-218
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• 2001

This paper deals with the control of magnetic field around the down conductor of lightning protection systems. The magnetic field strength in the vicinity of down conductor is shown to drop off rapidly with distance from the down conductor and is reversely proportional to the number of down conductor. Also the magnetic field strength is decreased in the structures as the down conductor is installed with the symmetrical arrangement, and it is zero at the center of symmetry. The magnetic field strengths for the symmetrical arrangement of two down conductors are less than one half compared with that for a down conductor. A proper arrangement of down conductor can reduce or cancel the magnetic field in a restricted place where information-oriented and computerized facilities are densely installed.

• The Transactions of the Korea Information Processing Society
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• v.7 no.5
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• pp.1553-1558
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• 2000

The development of recent computer and communication technology has changed Automation System using communication network, and the new USB substituted with Serial Communication is already developed and now popular. In this paper, High speed data transfer system design using USB interface and communication application simulated for the situation is introduced. Base on USB, we can use additive function efficiently coped with former field device. The 'Winsock Connection USB Ternimal,' designed for hardware simulation, control the field device connected by USB, and provide the way for remote control of field device by Telnet connection through TCP/IP. That theorem can guarantee controlling direct input dta of user, and acuate function of field device using USB Packet Transmission. As a result of amy research, this communication application system identified good operation of field device with those of former field device. Another result of the experiment of hardware operation, we obtained accomplishment that the sufficient bandwidth guarantee of USB has high speed and high performance, and reduce the occupancy of system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.3
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• pp.9-15
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• 2002

Due to the inconsiderateness of human capability and inappropriate arrangement of display and control unit at the industrial site, the human error leads to a various accidents. This study was performed to investigate the visual range at the eye field and stationary field at the various angles with three different visual stimuli of alphabetic character, color slip and light-emitting diode. Three kinds of various alphabetic characters depending on length and breadth ratio (1:1, 3:5, 5:3) and three different colors (red, yellow, green) were used for the stimuli. Twenty-five subjects (11 males and 14 females) participated for this study. The results showed that female had wider visual range than male at the eye field, however no significant difference was found at the stationary field. The light-emitting diode had a widest visual range then color slip and characters are in order at the eye field and stationary field. For the character stimulus, the widest visual range was shown at length and breadth ratio of 1:1. The other ratios (3:5 and 5:3) showed no significant difference. The color of red had a widest visual range on the light-emitting diode, however, the color of yellow showed a widest visual range on the just color slip at the eye field. The result of this study would be valuable in applying to the design of visual display and the panel layout of control and displays in the industrial site.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.18-24
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• 2010

This paper presents the improvement of the field uniformity in a reverberation chamber which can be substitute an anechoic chamber for the electromagnetic interference (EMI) and immunity test. Nowadays, there are many EMI issues due to the increasing use of wireless local area network (LAN), digital multimedia broadcasting (DMB), and mobile internet. With this reason, this paper studied the field characteristics in a reverberation chamber for 2.3 GHz band. In this paper, the finite difference time domain (FDTD) method is used to analyze the field characteristics in a reverberation chamber. To improve the field uniformity in the reverberation chamber, this paper adopted a 2D cubical residue diffuser (CRD) with varying the disposition and number of CRD. For each case, the tolerance and standard deviation of the electric field strength are evaluated. In comparison with the reverberation chamber without any CRD, the reverberation chamber with two CRDs showed improved results; 1.98 dB improvement in standard deviation and 3.6 dB improvement in tolerance.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1205-1210
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• 2004

The 4-20mA analog signal used in the various industrial fields to interface sensor in distributed process control has been replaced with relatively simple digital networks, called "fieldbus, and recently by Ethernet. Significant advances in Internet and computer technology have made it possible to develop an Internet based control, monitoring, and operation scheduling system for heating, ventilation and air-conditioning (HVAC) systems. The seamless integration of data networks with control networks allows access to any control point from anywhere. Field compatible field devices become so-called "smart" devices, capable of executing simple control, diagnostic and maintenance functions and providing bidirectional serial communication to higher level controller. The most important HVAC of BAS has received nationwide attention because of higher portion of more than 40% in building sector energy use and limited resources. This paper presents the Internet-based monitoring and control architecture and development of LonWorks control modules for AHU (air handling units) of HVAC in viewpoint of configuring BAS network. This article addresses issues in architecture section, electronics, embedded processors and software, and internet technologies.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.454-459
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• 2004

This paper considers the problem of satellite's orbit control and a solution based in Linear Matrix Inequalities (LMI) is proposed for the case of Low Earth Orbiters (LEO). In particular, the modelling procedure and the algorithm for control law synthesis are tested using as study case the European Gravity Field and Ocean Circulation Explorer satellite (GOCE), to be launched by the European Space Agency (ESA) in the year 2006. The scientific objective of this space mission is the recovering of the Earth gravity field with high accuracy (less than 10${\mu}m$/${\mu}m$) and spatial resolution (better than 100km). In order to meet these scientific requirements, the orbit control must guarantee stringent specifications in terms of environmental disturbances attenuation (atmospheric drag forces) even in presence of high levels of model uncertainty.

• Journal of Biosystems Engineering
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• v.17 no.3
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• pp.223-228
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• 1992

This study was conducted to develop an electro-hydraulic three-point hitch control system using an electro-hydraulic servo valve and microcomputer and to investigate the performance of the three-point hitch control system through indoor and field experiments. 1. The results from indoor experiments coincided with those from computer simulation reported in the previous paper. However, the draft control with the value 4 of Kd showed a slight sustained oscillation after it reached the draft set. 2. From the field experiments, it appeared that the RMS errors increased with the ground speed of tractor. In position control, the three-point hitch control system with electro-hydraulic servo valve showed better performance than that with on-off electro-magnetic valve in the ground speed less than 1.6 m/s. In draft control, however, there was no significant differece in performance between those two systems. 3. In depth control, the both types of electro-hydraulic three-point hitch control system showed better performance than the conventional mechanical-hydraulic three-point hitch control system.