• 전기학회논문지
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• 제65권3호
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• pp.499-503
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• 2016

For safety and economy reasons, hazardous waste including radioactive waste is desired to be converted into stable waste forms with a maximum volume reduction. High temperature melting technology using a plasma torch system can effectively treat even the non-flammable waste as desired. By far, one of the most difficult process for melting the non-flammable waste is a tapping of melts because the melting point of a residual slag in the tapping hole is high and because the viscosity of the melt increases sharply when tapping out. In case of a stationary furnace with a slant tapping port on the side of furnace, a certain amount of melts is left in the tapping hole after tapping out. Because of this, at every end of a melting cycle, the tapping hole needs to be opened by tapping device. The developed tapping device of melts based on both a guide electrode and auxiliary electrode is adequate for the application to discharge of melts except that the consumption of the guide electrode is somewhat faster than expected. Melt is collected in the water cooled vessel.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1859-1861
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• 2000

The high temperature thermal plasma technology applied to waste treatment has undoubtedly gained high importance owing to its outstanding properties such as flexibility, compact reactor. and clean treatment as the environmental problem goes to a main issue in public talks, because the thermal plasma with temperature of around 10,000K or little less is particularly suitable for waste treatment. Since the thermal plasma is, in general, governed by a number of parameters, some complicated and elaborate controls might be mandatory. The high maintenance cost caused by big input power has been a main obstacle to the growth of the waste treatment plant based on thermal plasma technology, but the recent R&D on the waste-to-energy shows that the problem could be solved soon. In this paper, the authors introduce the current R&D activity related to three-phase ac plasma torch in KERI.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.319-324
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• 2001

This paper presents the motion control of a mobile robot with arc sensor for lattice type welding. Its dynamic equation and motion control method for welding speed and seam tracking are described. The motion control is realized in the view of keeping constant welding speed and precise target line even though the robot is driven along a straight line or corner. The mobile robot is modeled based on Lagrange equation under nonholonomic constraints and the model is represented in state space form. The motion control of the mobile robot is separated into three driving motions of straight locomotion, turning locomotion and torch slider controls. For the torch slider control, the proportional integral derivative (PID) control method is used. For the straight locomotion, a concept of decoupling method between input and output is adopted and for the turning locomotion, the turning speed is controlled according to the angular velocity value at each point of the comer with range of $90^{\circ}$ constrained to the welding speed. The experiment has been done to verify the effectiveness of the proposed controllers. These results are shown to fit well by the simulation results.

• Journal of Mechanical Science and Technology
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• 제18권7호
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• pp.1094-1106
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• 2004

In this paper, a nonlinear controller based on sliding mode control is applied to a two-wheeled Welding Mobile Robot (WMR) to track a smooth curved welding path at a constant velocity of the welding point. The mobile robot is considered in terms of dynamics model in Cartesian coordinates under the presence of external disturbance, and its parameters are exactly known. It is assumed that the disturbance satisfies the matching condition with a known boundary. To obtain the controller, the tracking errors are defined, and the two sliding surfaces are chosen to guarantee that the errors converge to zero asymptotically. Two cases are to be considered: fixed torch and controllable torch. In addition, a simple way of measuring the errors is introduced using two potentiometers. The simulation and experiment on a two-wheeled welding mobile robot are provided to show the effectiveness of the proposed controller.

• 한국생산제조학회지
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• 제21권1호
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• pp.40-45
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• 2012

The glass edge sealing is one of the vacuum glazing core manufacturing process and it needs the high reliability for the vacuum keeping. Conventionally, the glass edge sealing had been being researched by the method that pasted the flit on the glass edge part and bonded two sheets of glass. But this way has the defect that can't make tempered glass. In order to remedy it's faults, in this paper, the glass edge was sealed by using the hydrogen mixture gas torch within the furnace. The parameter having an effect on the glass edge sealing through the basic test was set. And the correlation of the thickness of the glass edge and parameter were analyzed through the design of experiment. By using the Taguchi method, the optimal process condition for the glass edge sealing was drawn and the validity was verified.

• Journal of Welding and Joining
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• 제16권3호
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• pp.129-140
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• 1998

An interface system was developed to offer the welding capability to a robot controller which had not any embedded function for arc welding before, and also an arc sensor algorithm was proposed for weld seam tracking of the welding robot. For the interface system between the robot controller and welding equipments, data communication software and interface connections were composed. The interface system was mae to correspond welding condition, correction data, operation sequence and current status with the robot controller by mutual had shaking and digital signal transfer. Graphic user interface program developed under the environment of windows made it easy to monitor data communication and operation status, and to control welding and sensing sequence. Arc sensing algorithm proposed in this study to compensate torch position error was based on a fuzzy logic with the variables of current difference and current differenced change at torch weaving extremities. The developed interface system could be successfully implemented in between welding equipments and the robot controller, and showed normal status and exact function in data and signal communication between the systems. The whole robot welding system was then examined to verify its welding and seam tracking capabilities in horizontal fillet, vertical fillet, and 3-dimensional fillet weldment. The experiments revealed sound weld bead shapes and also good seam tracing results.

• 한국항행학회논문지
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• 제22권2호
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• pp.90-95
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• 2018

로켓 (rocket)이란 배출가스를 빠르게 분사하여 그 반작용의 힘으로 추진력을 발생시키는 추진 장치이다. 그리고 고체추진 로켓 (solid rocket motor)의 구조에서 노즐(nozzle)은 추력을 발생시키는 중요한 구성품으로 고온/고압 환경으로 인하여 연소되며 액체로켓 (liquid rocket propulsion systems)과 다르게 노즐을 냉각시킬 수 없어 연소가스에 의해 침식 (erosion)이 발생한다. 본 논문은 oxy-acetylene torch tester를 개발 및 이용하여 흑연 (graphite) 재질의 노즐목 (nozzle throat) 내열재에 대하여 열화학적 침식 특성을 실험 및 이론적 모델로 규명하고 이를 통하여 침식에 영향을 미치는 주요 인자에 대하여 연구하였다.

• Journal of the Korean Wood Science and Technology
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• 제49권1호
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• pp.82-92
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• 2021

Nakdong technique is an unfamiliar scorching treatment using an iron heated in a kiln over 1000℃. It is a typical convention in Asian countries to treat Nakdong on the surface of paulownia species. The scorching treatment changes the surface characteristics as well as the color of the wood. This study focused on the effects of functional features such as water resistance, anti-mold, anti-termite, and sound improvement because this treatment is usually used on paulownia wood-bodied musical instruments surface. It took 28'57" for Nakdong-iron treated surface to absorb a droplet of water. The absorbance time of iron treated surface was longer than that of torch treated one. There was no noticeable effect on the anti-mold test. On the anti-termite test, there was nearly 3% more mean mass loss on the torch samples than controlled and iron treated ones. In examining the sound radiation coefficient before and after Nakdong treatment, the Nakdong-iron treated surface showed an increase in the average value of 1.2 m4/kg s, which means that it has sound quality improvement. Through this research, the Nakdong technique results are expected to be used as basic-data for further research and give a practical idea for using the traditional treatment method on the wood surface.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.314-319
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• 2002

The Automation and Control Group at the University of Brasilia is developing an automatic welding station based on an industrial robot and a controllable welding machine. Several techniques were applied in order to improve the quality of the welding joints. This paper deals with the implementation of a laser-based computer vision system to guide the robotic manipulator during the welding process. Currently the robot is taught to follow a prescribed trajectory which is recorded a repeated over and over relying on the repeatability specification from the robot manufacturer. The objective of the computer vision system is monitoring the actual trajectory followed by the welding torch and to evaluate deviations from the desired trajectory. The position errors then being transfer to a control algorithm in order to actuate the robotic manipulator and cancel the trajectory errors. The computer vision systems consists of a CCD camera attached to the welding torch, a laser emitting diode circuit, a PC computer-based frame grabber card, and a computer vision algorithm. The laser circuit establishes a sharp luminous reference line which images are captured through the video camera. The raw image data is then digitized and stored in the frame grabber card for further processing using specifically written algorithms. These image-processing algorithms give the actual welding path, the relative position between the pieces and the required corrections. Two case studies are considered: the first is the joining of two flat metal pieces; and the second is concerned with joining a cylindrical-shape piece to a flat surface. An implementation of this computer vision system using parallel computer processing is being studied.

• International Journal of Korean Welding Society
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• 제2권1호
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• pp.45-51
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• 2002

In the multi-pass welding of pressure vessels or ships, the mechanical touch sensor system is generally used together with a manipulator to measure the gap and depth of the narrow gap to perform seam tracking. Unfortunately, such mechanical touch sensors may commit measuring errors caused by the deterioration of the measuring device. An automation system of narrow gap multi-pass welding using a laser vision system which can track the seam line of narrow gap and which can control welding power has been developed. The joint profile of the narrow gap, with 250mm depth and 28mm width, can be captured by laser vision camera. The image is then processed for defining tracking positions of the torch during welding. Then, the real-time correction of lateral and vertical position of the torch can be done by the laser vision system. The adaptive control of welding conditions like welding currents and welding speeds, can also be performed by the laser vision system, which cannot be done by conventional mechanical touch systems. The developed automation system will be adopted to reduce the idle time of welders, which happens frequently in conventional long welding processes, and to improve the reliability of the weld quality as well.