• International Journal of Precision Engineering and Manufacturing
• /
• 제5권3호
• /
• pp.5-10
• /
• 2004

Electric contacts serve the purpose of transmitting electric signals across two conducting components. In this paper, the effects of contact conditions such as surface roughness, oxidation, and contamination were investigated with respect to electrical resistance variation of a connector in a direct current circuit. Such change in the electrical resistance is particularly important for low power circuits. The experimental results showed that compared with the effects of contact surface scratch or oxidation, the effect of contamination on the resistance variation was the most significant. In order to minimize failure due to electrical resistance change at the contact region, proper sealing to prevent contamination from entering the interface is needed.

• 한국자동차공학회논문집
• /
• 제23권3호
• /
• pp.279-286
• /
• 2015

To achieve lightweight design, research & development of various lightweighting technologies such as hydroforming are underway worldwide. In the case of hydroforming, application of ultra high strength steel is essential for weight reduction of the car. However, considering common high-strength carbon steel, it is not suitable to the actual hydroformed parts since the lack of formability. DP steel offers an outstanding combination of strength and formability as a result of their microstructure. DP steel has high strength and good formability but it's difficult to secure stable quality of welding section because of softening of weld section and chemical composition. Therefore, most of companies use LASER welding when making high strength tube. Electric resistance welding is excellent production method for steel tube manufacturing considering the productivity. Optimum electric resistance welding technology is needed to be developed for application of high strength hydroformed parts using DP steel. This study is comprehensive research & development from electric resistance welding to actual formabililty evaluation.

• 설비공학논문집
• /
• 제26권8호
• /
• pp.351-356
• /
• 2014

Typical trouble patterns in solar thermal systems include working fluid leakage and freezing other than breakdown of pump. A fluid sensor for measuring electric resistance of fluid was developed and installed at the top of the collector piping in order to check the fault of solar system. Working fluid level in the pipe was determined by measuring electric resistance from a fluid sensor. On the base of this, it was confirmed that the fluid sensor diagnoses leakage of fluid. Electric resistance of propylene glycol aqueous solution was measured in the range of $0{\sim}70^{\circ}C$ and 0~40% of concentration. The response surface analysis was performed by using a central composite design, and the regression equation was derived from the relationship between electric resistance, temperature, and concentration. Through the experiment in a real solar system, we can estimate a concentration of working fluid when a pump is not operating and predict a possibility of freezing. Finally, an effective algorithm for trouble shooting was proposed to operate and maintain the solar system.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2022년도 가을 학술논문 발표대회
• /
• pp.235-236
• /
• 2022

Electric vehicle fires in underground parking lots are very dangerous, but it is judged that the current related laws and regulations do not change, which will cause problems. As a result of the analysis for the purpose of providing an electric vehicle in an underground parking lot, fire-resistance coating is essential as it can cause an explosion in the building members made of high-strength concrete when an electric vehicle fire occurs in an underground parking lot. Since a fire occurs, it is necessary to prevent electric vehicles from parking adjacent to each other.

• 한국전기전자재료학회논문지
• /
• 제17권1호
• /
• pp.107-111
• /
• 2004

This work describes the effect of composite conductor on the characteristics of electric double layer capacitor. Test cell, which was fabricated with conducting composite consisted of 80％ of SPB and 20％ of VGCF, exhibits the better tate capability and the lower resistance than those of the cells fabricated with single electronic conductor. These enhanced properties could be related with the decrease of contact resistance between the activated carbon powders.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2004년도 추계학술대회 논문집
• /
• pp.988-993
• /
• 2004

This paper considers corrosion problems in the bolt connection of weathering steel box girder bridge using the external electric type corrosion resistance method which resisted to local corrosion in coated steel surface with contacted air. The weathering steel was created a rust itself in the passive state. but a coated box girder type was easily dew form could be made galvanic cell that accelerated corrosion. so that it was ruled by protection coat with some paint. Therefore, it needed that can be applied the external electric type corrosion resistance method in coated surface. As a result of the test of polarization amount had measured that the weathering steel was higher currents than the general steel by about $5\~10\%$. Therefore. an external electric type corrosion resistance method can be used to protect local corrosion in the coated bolt connection of weathering steel box girders effectively.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.671-674
• /
• 2000

A children's electric shock accidents have broken out because children can easily insert sharp things in 220V receptacle holes. As the test result of pushing force, children's pushing force was about 2-4kg and the pushing force of sharp things was less than 2kg. Therefore, it is reason for electric shock that children's pushing force is large than pushing force of sharp things. We have measured insulation resistance for the receptacles of five companies during 50 weeks in humid condition. As these results, Insulation resistance for the receptacles of J. Co. had rapidly decreased with lapse of time. As the result for investigating the surface of receptacle by SEM and EDX, Al, Fe and Br, which weren't discovered at original form, were produced. Therefore, the receptacles of J. Co. should be the improved in the quality of insulating material because insulation resistance can be decreased in humid environment

• 한국지반공학회논문집
• /
• 제17권6호
• /
• pp.225-233
• /
• 2001

본 논문에서는 격자망식 전선배치에 의한 침출수 누출감지시스템을 개발하기 위하여 현장모형시험을 통하여 적용성을 평가하였으며, 전기회로시험을 통하여 격자망 전선 배치에서 발생하는 전기회로적 효과를 파악하고자 하였다. 침출수는 전기저항을 감소시키기 때문에 누출지점에서는 다른 지점에 비해 낮은 전기저항값을 나타내었다. 따라서, 전기저항을 측정하는 본 누출감지시스템에 의하여 임의 지점에서 발생하는 침출수의 누출 감지가 가능하였으며, 평면적 분포도를 통하여 누출위치의 파악이 가능하였다. 전기저항이 감소된 지점과 동일한 전선상에 위치한 다른 센서에 서의 측정값도 약간 감소하는 경향을 나타내었으나, 이는 저항이 작은 곳으로 전류의 흐름이 발생하는 전기회로적 효과로 설명할 수 있었다.

• Tribology and Lubricants
• /
• 제30권2호
• /
• pp.99-107
• /
• 2014

Fretting corrosion tests are conducted with a constant displacement amplitude using silver-plated brass coupons to investigate the effect of contact pressure on fretting corrosion. Three behaviors are identified based on the change in electric resistance and friction coefficient during the fretting test period, and the identified behaviors are dependent on the magnitude of the applied load. The failure cycle ($N_f$) with an electric resistance of 0.1 D cannot be achieved due to the adhesion behavior of the metal and metal contact under the higher applied load of 0.45 N. This suggests that an average contact pressure higher than 159 MPa for the silver-coated connector is desirable to gain an almost infinite lifetime. The relationship between the electric contact resistance (R) and the average contact pressure (p) can be written as $p=106.2{\times}{\Omega}^{-1.5}$.

• 한국기계가공학회지
• /
• 제21권3호
• /
• pp.1-11
• /
• 2022

In this study, an electric resistance dual-spot welding process using a copper electrode inserted in a heating electrode is suggested for the spot welding of AZ31 magnesium sheets. This spot-welding process involves two heating methods for welding at the interfacial zone between the magnesium sheets, one of which is the heating method by thermal conduction from the heating electrode heated by the welding current induced to the steel electrode, and the other heating method uses the electric resistance between the contacted surfaces of the two sheets by the welding current induced to the copper electrode. This welding process includes the welding variables, such as the current induced in the heating electrode and the copper electrode, and the outer diameters of the heating electrode. This is because the heat conducted from the heating electrode can be maintained at a higher temperature in the welding zone, which has a slow cooling effect on the nugget of the melted metal after the welding step. The pressure exerted during the pressing of the magnesium sheets by the heating electrode can be increased around the nugget zone at the spot-welding zone. Thus, it not only reduces the warping effect of the elastoplastic deformation of sheets, but also the corona bond can make it less prone to cracking at the welded zone, thereby reducing the number of nuggets expelled out of the corona bond. In conclusion, it was known that an electric resistance dual spot welding process using the copper electrode inserted in the heating electrode can improve the welding properties in the electric resistance spot welding process of AZ31 magnesium sheets.