• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.680-684
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• 1996

Welding systems cannot adapt to changes in the joint geometry which may occur due to a variety of reason. Automatic seam tracking technigue is essential to adjust the welding torch position in real time as it moves along the seam. Automatic tracking system must keep the welding speed constant unrelation to the change of the welding path. Therefore, the information from the laser displacement sensor must be converted into the input to operate the X-Y table and to rotate the desired torch position by proposed algorithm. In this research, laser displacement sensor is used as a seam finder in the automatic tracking system. X-Y moving table manipulated by ac servo motor controls the position and velocity of the torch-and-sensor part. DC motor controls the position and velocity of the torch. X-Y table controls the position of sensor and relative position of torch is controlled by dc motor which is mounted at sensor-and-torch part. Sensor is always ahead of torch to preview the weld line. From the experimental results, we could see the possiblity that the laser displacement sensor can be used as a seam finder in welding process and that the seam tracking system controlled by proposed algorithm is well done.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.70.1-70.1
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• 2018

자동차를 포함한 수송기기, 전기 및 전자산업에 있어 경량화, 소형화, 고성능화와 함께 에너지 및 원가절감을 위한 노력이 활발하게 이루어지고 있다. 알루미늄은 신소재 및 고효율 제조공정 개발을 위한 합금설계기술, 용해/주조 기술, 가공기술, 열처리 기술, 시험평가 기술, 시뮬레이션 기술에 대한 전방위적인 연구가 진행되고 있다. 최근 프리미엄 자동차 시장에 고강도 알루미늄을 이용한 휠 시장이 폭발적으로 증가하고 있다. 2010년 전세계 자동차 휠 시장 규모는 56조원으로 알루미늄 휠 시장 규모는 약 19조원으로 점차 증가하고 있으며, CO2 배출 및 연비 증가에 대한 시대적 요구에 의해 수송기기의 경량화 및 주행 성능 향상으로 알루미늄 휠 시장 규모는 해마다 증가하고 있다. 7xxx 계열의 알루미늄 합금을 이용해 PEO (Plasma Electrolytic Oxidation) 혹은 MAO (Micro Arc Oxidation)를 이용해 표면처리를 수행하였다. 표면처리는 Silicate, Vanadate 및 Phosphate 등의 전해액을 선택적으로 사용하였으며, AC 200 ~ 500 V의 전압 조건 범위에서 CV 모드로 전류를 인가하였다. 형성된 표면 산화층은 산화막 두께 분석, 내마모 특성 평가, 염수분무 평가, 전기화학 평가(Potentiodynamic Polarization) 등을 통해 표면 산화층 분석을 진행하였다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권2호
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• pp.120-124
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• 2000

In this paper, the effect of magnetic field was measured on NOx(NO+NO2) removal and consumption power for wire-plate plasma reactor with magnetic field applied to electric field vertically. NOx of the simulated diesel engine flue gas were removed by the corona discharge generated by DC, AC and Pulsed voltages in wire-plate reactor. Consumption power increased with discharge voltage. However, when magnetic field was applied to electric field vertically, consumption power slightly decreased. NOx removal rate and arc transition voltage for plasma reactor with magnetic field were higher than those for plasma reactor without magnetic field. Consumption power decreased, however NOx removal significantly increased, when water vapour bubbled by dry air was put into simulated flue gas.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 추계학술발표 개요집
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• pp.3-15
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• 1996

The formation of a thicker hard alloyed layer have been investigated on the surface of aluminum cast alloy (AC2B) by PTA overlaying process with Cr, Cu and Ni motel powders under the condition of overlaying current 125-200A. overlaying speed 150 mm/min and different powder feeding rate 5-20 g/min. In addition the characteristics of hardening and wear resistance of alloyed layer here been examined in relation to the microstructure of alloyed layer. Main results obtained were summarized as follows: 1) There was an optimum overlaying condition to get a good alloyed layer with smooth surface. This good layer became easy to be formed as increasing overlaying current and decreasing powder feeding rate under a constant overlaying speed. 2) Cu powder was the most superior one in metal powders used due to a wide optimum overlaying condition range, uniform hardness distribution of Hv250-350, good oar resistance and freedom from cracking in alloyed layer with fine hyper-eutectic structure. 3) On the contrary, irregular hardness distribution was usually obtained in Cr ar Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv400-850 at about 60wt%cr or 40wt%Ni in alloyed layer. 4) Cracking occurred in Cr or Ni alloyed layers with higher hardness than Hv250-300 at mere than 20-25wt% of Cr or Ni contents in alloyed layer. Porosity was observed in all alloyed layers but decreased by usage of spherical powder with smooth surface.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.356-361
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• 2005

Earth brush for electrical multiple units(EMUs) is a device through which the current of the EMU load's consumed power fed from the DC 1,500V overhead line (or from the AC 25.000V catenary) flows via axle to the rail(ground) and which prevents the electric corrosion of the axle bearings by preventing the current flow to the axle bearings caused by electric potential from the magnetic field when the bearings rotate together with the earthing function when a thunderbolt falls or a surge comes. The earth brush wear rates among cars, however, shows quite differences when the earth brushes after being separated from the holders are measured with vernier callipers every 6 months of maintenance period. Main causes of the earth brush wear are divided as mechanical, electric arc and electrical one, and the factors can be running speed, current, harmonics, connection state. spring tension, earth brush material, lubricant and so on. but only the earth brushes of the motor(M1) car show the highest wear rate and moreover maintenance difficulty occurs because of the wear rate differences among e earth brushes in one holder. The reason for these preponderant wear comes from the design concept of making preponderant current flow to some particular earth brushes and moreover the heat generated by the harmonics when the inverter starts to operate accelerate the wear. By defining these causes through experiments. I hope that the found results would be helpful for the future EMU design, safety, economy and maintenance.

• 전기의세계
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• 제28권7호
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• pp.49-55
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• 1979

본논문은 Thyristor를 이용하여 교류회로의 고장전류를 차단하는 기구에 대한 것이다. 즉 Thyristor 한류차단회로를 설정하고 게이트제어회로 과전류검출기를 설계하고 동작과정을 확인하였다. 결과에 있어서 (1) 고속차단이 가능하다(60Hz 교류에서 4ms이내) (2) 이 방식에 의하면 차단용량을 감소시킬 수 있다. (3) 적은 신호로 지체없이 동작한다. (4) 기계적부분이 없으므로 반영구시 수명을 가진다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.70-75
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• 2002

The penetration potential of TIG welding in one single run is limited, though the process itself generates high quality welds with good weld cosmetics. This is one of the main reasons, which has contributed to its development in high duty applications such as those encountered in aeronautical, aerospace, nuclear & power plant applications. For these applications, stainless steels, titanium k nickel based alloys are most often used. As these materials remain very sensible to weld heat input k atmospheric pollution, stringent processing conditions are imposed. For example welding of titanium alloys requires argon shielding of weld zone and for 5 mm thick plates multi-pass runs & filler additions are required. This multi-run operation not only raises the welding cost, but also increases defect risks. In recent years, extensive interest has been raised by the possibility to increase weld penetrations through flux applications & the process is designated ATIG-activated TIG, or FBTIG-flux bounded TIG. The improved welding performance of such flux assisted TIG is related to arc constriction and surface tension effects on weld pool. The research work by authors has lead to the formulation of welding fluxes for stainless steels k titanium alloys with TIG Process. These fluxes are now commercialized & some applications in industry have already been carried out. FBTIG for aluminum has been proposed with silica application for AC mode TIG welding. The paper highlights the fundamentals of flux role in TIG welding and illustrates some industrial applications.

• 한국조명전기설비학회지:조명전기설비
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• 제9권1호
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• pp.23-29
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• 1995

본 논문에서는 고압방전등 전자안정기의 제작시 발생하는 음향공진 현상을 방지하기 위해서 방전등에 55.5[Hz]구형파를 인가하였고, 이 경우 방전등의 부저항특성 및 방전등의 시동특성에 효과적으로 대응하기 위해 인버터에 공급되는 전원을 정전류 쵸핑에 의한 DC전압으로 하였다. 설계된 전자안정기는 220[V]AC전원 전압을 정류하고, 스위칭 주파수가 30[kHz]인 정전류 쵸핑으로 방전등의 관전압에 맞는 DC전압을 인버터에 공급하며, 인버터에서 55.5[Hz]의 구형파를 방전등에 인가하도록 설계하였다. 설계한 전자안정기를 제작하여 실험한 결과, 비교된 재래식 안정기보다 효율이 향상되고, 플리커현상이 발생하지 않으며, 방전등 시스템의 정전력화 및 조광기능을 갖추고 있어서 탁월한 실용성을 입증하였다. 제작한 전자안정기의 용량은 300[W] 입력전압은 220[V]이며, 실험에 사용한 램프는 정격전력이 300[W]이며 관전압 135[V] 관전류는 2.0[A]로서 측정하였다.

• 한국재료학회지
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• 제11권4호
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• pp.283-289
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• 2001

50/50 vol% LSM-YSZ (La$_{1-x}$Sr$_{x}$MnO$_3$-yttria stabilized zirconia)의 복합공기극이 콜로이드 증착법에 의해 연마된 YSZ 전해질상에 증착되었다. 그 전극 특성은 주사전자현미경, X선회절과 임피던스 분석기에 의해 연구되어졌다. 90$0^{\circ}C$에서 공기/LSM -YSZ/YSZ/Pt/공기 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호(depressed arc)로 구성되었다. LSM 전극에 대한 YSZ의 첨가는 전극내의 삼상계(TPB) 영역을 증가시켰으며, 이것이 LSM-YSZ 복합공기극의 비저항을 감소시켰다. 또한 전해질 표면의 불순물 제거와 TPB 길이의 증가를 위한 전해질 표면연마는 공기극의 비저항을 훨씬 더 감소시켰다. LSM-YSZ 공기극의 비저항은 작동온도, 공기극의 조성과 입자크기, 인가전류 및 전해질의 표면거칠기에 의해 큰 영향을 받았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1536-1539
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• 1994

The influence due to metallic particle contaminated on spacer surface is remarkable in the decreasing of dielectric strength in $SF_6$ GIS. In relation with this problem, We studied, AC flash-over voltage characteristics and breakdown mechanism are investigated under metallic particle initiated condition in $SF_6$ gas by varying the particle position, particle shape with a plane-plane electrode. The main results arc as follows 1. The small amount of the metallic particle in the gap do not make flash-over voltage to be influence, but the significant decrease of th flash-overed voltage is result in case of the big and long size of the metallic paraticle. 2. Influence of the flash-over voltage are lowest in the mid and are highest in the electrode of metallic particle position. 3. In case of the initiated metallie particle, The more the pressure are high, the more the recluced ratio of flash-over voltage are high. 4. The metallic particle shape which results in the reduced flash-over voltage forced the critical pressure to move in to the region of low pressure. 5. The existance of the metallic particle on the upper electrode side and high pressure make the decreasing ratio of flash-over voltage bigger than that of the ground side electrode.