• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.152-160
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• 1999

The weld quality of $CO_2$ arc welding is closely related to the arc stability. As the characteristics of the arc are excessively complex and nonlinear, it is not easy to make the arc model as mathematical form and to control the arc state to be stabilized. This paper was aimed to estimate the arc stability and to control for stabilizing the arc state in short circuit metal transfer mode of $CO_2$ arc welding. For these purposes, the behaviors of arc stability was investigated at different welding conditions using Mita's arc stability index, and the fuzzy control algorithm which uses the arc stability index as control imput and the arc voltage as control output was developed. In the control of the arc stability, the experiments of two cases were performed; the case of setting an initial welding voltage arbitrarily, the case of the step change in workpiece shape. Obtained results were as follows; Mita's arc stability index was able to be estimated qualitatively in the case of using the inverter type welding power source and the control performance for stabilizing the arc status was excellent in the case of existing step change disturbance.

• Transactions on Electrical and Electronic Materials
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• v.1 no.2
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• pp.12-17
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• 2000

Helicon waves were excited by a Nagoya type III antenna in magnetized plasma, and hydrogen and methane are fed through a Mass Flow Controller(MFC). We made a diagnosis of properties of helicon plasma by H$_2$gaseous discharge, and fabricated the diamond thin film. The maximum measured electron density was 1${\times}$10$\^$10/ cm$\^$-3/. Diamond films have been growo on (100) silicon substrate using the helicon plasma chemical vapor deposition. Diamond films were deposited at a pressure of 0.1 Torr, deposition time of 40~80 h, a substrate temperature of 700$^{\circ}C$ and methane concentrations of 0.5~2.5%. The growth characteristics were investigated by means of X-ray Photoelectron (XPS) and X-ray Diffraction(XRD), XRD and XPS analysis revealed that SiC was formed, and finally diamond particles were definitely deposited on it. With increasing deposition time, the thickness and crystallization of the daimond thin film increased, For this system the optimum condition of methane concentration was estimated to near to 1.5%.

• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.2
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• pp.1-6
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• 2006

The pressure regulator which is used for controlling the reducing pressure in the piezoelectrically driven pneumatic valve has been studied. The pneumatic valve of this study object is 2-stage type and consists of a piezoelectric actuator, a controller, a poppet valve and a pressure regulator. Nominal flow of 50 lpm, maximum operating pressure of 0.9MPa and frequency characteristic of 10Hz and over are required in this pneumatic valve, but the pressure regulator is needed because piezoelectric actuator has no ability to control the pressure of 0.9MPa directly. In this study, bimorph type PZT actuator of $25.2mm(L){\times}7.2mm(W){\times}0.5mm(H)$ with constant of $-220{\times}10-12$ CN-1 was proposed and investigated. Maximum operating force of 0.052 N and maximum displacement of $63{\mu}m$ were gotten from the fabricated PZT actuator. From the analysis results, the orifice diameter of 0.6mm for a piezoelectric actuator was derived and then the pressure regulator which can be operated under 0.15 MPa easily was designed and manufactured. Performance and effects of design parameters were simulated by the Simulink of Matlab software, and it was confirmed that the performance characteristics of manufactured pressure regulator are superior in the common use pressure range of 0.5 MPa to 0.7 MPa. The results show that the proposed pressure regulator is suitable for the pneumatic valve with a PZT actuator.

• Land and Housing Review
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• v.5 no.4
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• pp.325-332
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• 2014

The purpose of this study was to measure the airtightness and Air-Flow Performance for 7th house of small apartment houses adopted window frame-type natural ventilation. All window and living room door is provide with window frame-type natural ventilation, and there is provide with manual controller. As the object of measurement, the 6th type small apartment houses with area of $33m^2$ to $51m^2$ was selected. airtightness performance was measured at the front door using Blower door system. We measured ventilation rate per hour on 50Pa pressure different between inside and outside by the 1st to 6th cases. As a result, when the natural ventilation frame was closed, average amounts are shown as the ventilation rate per hour were 2.27ACH (CASE1). and the result is similar to general apartment house (1.65~4.28ACH). When the natural ventilation frame was open, average amounts are shown as the ventilation rate per hour were 5.87ACH (CASE6). In addition, that's a 3.6ACH increased more than CASE1.

• 전자공학회논문지 IE
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• v.43 no.4
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• pp.28-36
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• 2006

In this paper, an algorithm to classify the 4 motions of arm and a control system to position control the prosthesis are studied. To classify the 4 motions, we use flex sensors which is electrical resistance type sensor that can measure warp of muscle. The flex sensors are attached to the biceps brchii muscle and coracobrachialis muscle and the sensor signals are passed the sensing system. 4 motion of the forearm - flexion and extension, the pronation and supination are classified from this. Also position of forearm is measured from the classified signals. Finally, A two D.O.F prosthesis arm with RC servo-motor is designed to verify the validity of the algorithm. At this time, fuzzy controller is used to reduce the position error by rotary inertia and noise. From the experiment, the position error had occurred within about 5 degree.

• The Transactions of the Korea Information Processing Society
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• v.1 no.2
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• pp.263-271
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• 1994

Automation of production in modern manufacturing is based on the integration of the various stage of production process by means of processing system. Information processing and network interface are of fundamental importance in programmable device in industrial automation, as they essential in order to active integration in production lines. In this paper, TBC(token bus controller) in the Mini-MAP board performs the function of the MAC sublayer, The LLC sublayer is implemented according to the specification of Class 3 that includes Type 1 and 3. And the MMS services are designed within the scope of implementation MAP 3.0 All the softwares are implemented under the real time executive for real time application of the Mini-MAP and they are loaded into PROMs at the network board. We tested the LLC functions to make use of a protocol analyzer for the token bus protocol. Also the MMS conformance test was carried out by exchanging primitives between a model system(including NIU) and a MMS product that had already passed the conformance the conformance test based on measurement method of network analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.629-635
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• 2009

The FSK duplex remote controlling wireless transmission units with a common local oscillator circuit for transmitter and receiver are designed and implemented in this paper. In the FSK full-duplex the channel frequency for Tx/Rx is allocated, a common switching oscillator circuit for Tx/Rx is designed in the FSK half-duplex scheme. Both of FSK units get functions of automatic channel detection for busy channels and channel configuration for an idle channel in order to reduce the RF channel interference and are designed as a remote controller with small-sized low power of 10mW and the 400MHz-colpitz type PLL configuration of 50kHz channel separation. The full-duplex Tx/Rx link frequency gets frequency difference of 42.8MHz, which is double of 21.4MHz IF frequency.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.15-22
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• 1998

The goal of this paper is to propose analyzing and evaluating method of power parameters for motor drive system with various experimental graphic screens and numerical results and to develop the proposed system. A developed system is made up 586-PC and DSP board, motor drive system, power parameters analyzing and evaluating software for windows. Power parameters are analyzed using correlation signal processing techniques based on the correlation between voltage and current waveforms. Analysis results are visualized by 3-D current coordinates, and it is compared and evaluated with conventional time/ frequency domain. To verify the validity of the proposed system, capacitor run type single phase induction motor and thyristor speed controller is used for analyzing. Power and harmonic parameters of motor drive system is analyzed and verified, with varying fire angle of thyristor speed controller, and the proposed approach is to confirm validity.

• Journal of Drive and Control
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• v.21 no.2
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• pp.36-43
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• 2024

The yield is basic and necessary information in precision agriculture that reduces input resources and enhances productivity. Yield information is important because it can be used to set up farming plans and evaluate farming results. Yield monitoring systems are commercialized in the United States and Japan but not in Korea. Therefore, such a system must be developed. This study was conducted to develop a yield monitoring system that improved performance by correcting a previously developed flow sensor using a grain tank-weighing system. An impact-plated type flow sensor was installed in a grain tank where grains are placed, and grain tank-weighing sensors were installed under the grain tank to estimate the weight of the grain inside the tank. The grain flow rate and grain weight prediction models showed high correlations, with coefficient of determinations (R2) of 0.9979 and 0.9991, respectively. A main controller of the yield monitoring system that calculated the real-time yield using a sensor output value was also developed and installed in a combine harvester. Field tests of the combine harvester yield monitoring system were conducted in a rice paddy field. The developed yield monitoring system showed high accuracy with an error of 0.13%. Therefore, the newly developed yield monitoring system can be used to predict grain weight with high accuracy.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.44-53
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• 1993

In this paper, we discuss on the control algorithm to make the wheeled inverse pendulum type mobile robot move in two dimensional plane. The robot considered in this paper has two independently driven wheels in same axel which suport and move it-self, and is assumed to have the fyro type sensor to know the inclination algle of the body and rotary encoders to know wheel's rotation angular velocity. The control algorithm is divided into three parts. The first part is for the posture and velocity control for forward-backward direction, the second is the steering control, and the last part is for the control of total system to track the given trajectory. We handle the running velocity control of the robot as part of the posture control to keep the balance because the posture relates deeply with the velocity and can be controlled by the velocities of the wheels. The control problem is analyzed as the tracking control, and the controller is realized with the state feedback and feed-forward of the reference velocity. Constructing the control system which contained one intergrator in forward path, we also realized the control system without observer for the estimation of the accumulated errors in the inclination angle of the body. To prevent the robot from being unstable state by sudden variation of the reference velocity when it starts and stops, or changes velocity, the reference velocity of which acceleration is slowly changing, is ordered to the robot. To control its steering, we give the different reference velocities for both wheels which are calculated from the desired angular velocity of the body. Finally, we presents the experimental results of the experimental robot Yamabico Kurara in which the proposed control algorithm had been implemented.