• 대한전자공학회논문지
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• 제26권7호
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• pp.98-105
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• 1989

본 논문에서는 생체 조직을 정량화하기 위한 음속의 측정법을 제안하였다. 기존의 음속 측정법에서는 주파수 분산의 영향이 무시되고 있으나, 주파수 분산은 전파 지연에 영향을 미친다. 따라서 진폭 스펙트럼으로부터 최소 위상 스펙트럼을 유도하여 주파수 분산을 정량화하였으며, 주파수 분산을 제거하기 위한 신호 분해법을 제안하였다. 또한 컴퓨터 시뮬레이션을 통하여 제안된 이론의 유효성분을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.152-157
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• 2005

Recently, higher speeds have been promoted in old overhead-lines. For high-speed operation in electric railways, increasing contact loss of the pantograph is one of the most important subjects. The contact loss causes power interruption and increases wear of contact strips and contact wires. In order to investigate the causes of contact loss and to work out effective improvement methods, theoretical analyses, experiments have been carried out. First of all, the wave propagating velocity (phase velocity) and characteristics of contact wire are one of the important indices for the current collecting performance. In this paper, mathematical formula arc derived for the prediction of the traveling wave velocity. The measured values in the experiment agree well with the theoretical predictions.

• 한국화재소방학회논문지
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• 제29권6호
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• pp.65-70
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• 2015

본 연구는 울산소재 석유공장의 건조시설에서 발생하는 가스를 스크러버(Scrubber)로 최종 처리하여 배출되는 저 농도의 유해가스와 산 처리 시설에서 발생되는 고 농도로 발생하는 유해가스를 대상으로 연구하였다. 공정별로 벤젠(Benzene), 톨루엔(Toluene), 자일렌(Xylene) 및 총휘발성유기화합물(TVOCs)을 대상으로 측정하였으며 농도 측정은 TVOCs 측정기와 GC-MSD를 이용하여 SAP 전 후단의 TVOCs와 BTX의 농도를 측정, 분석하여 제거효율을 평가하였고, SAP 반응기는 5 단계로 구성하여 실험을 수행하였다. 슬라이딩 아크 프라즈마(slidind arc plasma) 반응기의 단수별에 따른 TVOCs 농도 변화는 유입 TVOCs 농도의 변화에 따른 처리효율 결과 481 ppm 미만에서 94.83%, 481 ppm 이상일 경우에는 1단에서는 89.07% 2단에서는 약 91% 이상으로 처리되는 것을 확인할 수 있었다. 본 연구의 결과는 석유화학공정 및 제조시설에서 SAP 공정을 통한 VOCs 제거에 대한 연구 및 기술개발의 기초가 되어 VOCs의 보다 안정적인 처리와 다양한 기술개발에 효과가 있을 것으로 기대해 본다.

• Journal of Welding and Joining
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• 제29권3호
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• pp.51-57
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• 2011

Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was designed by using the Venturi meter and compared velocity, pressure, arc shape in the flat position with existing CP-nozzle. As a result, Venturi-type nozzle's maximum velocity and pressure was improved at the same flow rate. Also heat input was increased by the arc contraction in the flat position.

• Journal of Welding and Joining
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• 제13권4호
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• pp.122-131
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• 1995

An automatic welding equipment for thick plates requires the capability of the seam tracking of the weld line which often includes misalignment of the workpiece and variation of groove width. In this study, an automatic welding equipment and control algorithms based on the arc sensor were proposed for the GMA welding of thick plates which had misalignment and gap variation. The developed system being constituted with 5 axis can be automatically controlled by computer and also automnatically set the welding conditions such as welding current, and voltage. The proposed algorithms for the seam tracking in multi-pass welding of the thick plates were constituted as follows : the detection of weaving-end point for findng the variation of groove width, the control of welding velocity for acquiring a constant thickness deposition of weld metal, and the calculation of groove width and height of an arbitrary pass in the multi-pass weld. As results of the application of the system, it was revealed that the system had a good capability in seam tracking and made an excellent weld quality in V groove butt joint.

• 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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2494-2499
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• 2007

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. The high-current simulation provides information about the mixing process of the hot PTFE cloud with $SF_6$ gas which is difficult to access for measurement. But it is also hard to simulate flow phenomenon because the flow in interrupter with high current, $SF_6$-PTFE mixture vapor and complex physical behavior including radiation, calculation of electric field. Using a commercial computational fluid dynamics(CFD) package, the conservation equation for the gas and temperature, velocity and electric fields within breaker can be solved. Results show good agreement between the predicted and measured pressure rise in the thermal chamber.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.729-733
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• 1997

Due to the variety of disturbance, it is not ease to accomplish the in-process detection of weld line with non-contact sensor. To get around this difficulties problem develop an automatic seam tracking weld system, the reliable signal processing algorithm has been recommanded. In this research, laser displacement sensor is applied as a seam finder in the automatic tracking system. The sensor is controlled by a dc servo motor which is mounted at X-Y moving table. X-Y moving table manipulated by an ac servo motor controls the position and velocity of the welding torch. First, X-Y table moves to Y-axis to search the welding joint feature before starting the welding, and welding joint is from the scanning data and weighting factor for each other. Second, weld line is determined using proposed signal processing algorithm during welding process. Form the experimental results, we could see the possibility that laser displacement sensor with procesed algorithm can be used as a seam finder in welding process under the severe noise (spatter,arc light etc.) condition

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1837-1839
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• 1997

This study presents the energy transfer of thermal arc in the circuit breaker with self-generation flow without puffer action. The phenomenon of pressure increase in the cylinder which encloses fixed contact was focused on and rising current stage was considered. Temperature and velocity of arc plasma were calculated by using energy balance equation and the amount of energy transfer due to convective flow was calculated.

• 플랜트 저널
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• 제6권3호
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• pp.46-52
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• 2010

This study investigated the coating failure of the blades of booster fans for the 200 MW flue gas desulfurization plant. Although the arc sprayed SM8222 have been tried as blade coating materials aimed to apply as alternatives of Metcoloy(R)2 due to better corrosion-erosion resistance but it is failed. Bond strength tests and practical field experiences have demonstrated high velocity oxy-fuel(HVOF) coating method with Diamalloy 3004 as an alternative to Metcoloy(R) 2 arc spray.