• Proceedings of the KSME Conference
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• 2001.06a
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• pp.377-382
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• 2001

Mechanical behavior and electrical resistance change of CPDP (carbon particle dispersed plastic) composite consisting of epoxy resin and conductive carbon particle were investigated under monotonic loading and repeated loading-unloading. The electrical resistance almost linearly increased with increasing strain during loading and the residual electrical resistance was observed even after removing load. The value of the residual electrical resistance was dependent on the maximum strain under the applied stress. This result suggests that the estimation of maximum strain (i.e., damage) is possible by the measuring electrical resistance of composite. The behavior of electrical resistance change during and after loading was discussed on the basis of the results of microscopic deformation and fracture observation. Moreover, the relationship between the volume fraction of carbon particle and the electrical resistivity of CPDP was investigated in relation to the percolation theory. Simulation model of percolation structure was established by Monte Carlo method and the simulation result was compared to the experimental results. The electrical resistance change under applied loading was analyzed quantitatively using the percolation equation and a simple model for the critical volume fraction of carbon particle as a function of the mechanical stress. It was revealed that the prediction was in good agreement with the experimental result except in the region near the failure of material.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1013-1015
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• 1995

The electrical properties of Al/TiN/Ti contact according to post anneal ins conditions are investigated at submicron contacts. $N^+$ contact resistance increases with increasing alloy temperature while $P^+$ contact resistance slightly decreases. The contact tentage current increases wi th increasing alloy temperature for both $N^+$ and $P^+$ contacts. The contact resistance and leakage current of $N^+$ contact increases with increasing alloy tide. $P^+$ contact resistance decreases with increasing alloy time but $P^+$ contact tentage current increases. The contact resistance and contact leakage current increases with increasing alloy cycles for both $N^+$ and $P^+$ contacts.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.6
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• pp.365-369
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• 2016

In this paper, we fabricated Cu/Mn alloy shunt resistor with low resistance and thermal stability for use of mobile electronic devices. We designed metal alloy composed of copper (Cu) and manganese (Mn) to embody in low resistance and low TCR which are conflict each other. Cu allows high electrical conductivity and Mn serves thermal stability in this Cu/Mn alloy system. We confirmed the elemental composition of the designed metal alloy system by using energy dispersive X-ray (EDX) analysis. We obtained low resistance below $10m{\Omega}$ and low temperature coefficient of resistance (TCR) below $100ppm/^{\circ}C$ from the designed Cu/Mn alloy resistor. And in order to minimize resistance change caused by alternative frequency on circuit, shape design of the metal alloy wire is performed by rolling process. Finally, we conclude that design of the metal alloy system was successfully done by alloying Cu and 3 wt% of Mn, and the Cu/Mn alloy resistor has low resistance and thermal stability.

• Composites Research
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• v.26 no.3
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• pp.201-206
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• 2013

The electrical resistance measurement was investigated as a damage monitoring method. In this study, 0.5 wt% Carbon nanotube reinforced polypropylene (CNT/PP) composites were evaluated under compressive fatigue loading. The shape of specimens was $20^{\circ}$ curved round type. Compression strength and electrical resistance were measured at different sections of specimen during compression. The microcracks of CNT/PP composites were detected based on the changing ratio of electrical resistance. Micro-damage during compressive fatigue test could be detected by electrical resistance measurements. The reason is that the contact points of CNTs in composites decreased under fatigue loading. During compressive fatigue test, larger change of electrical resistance was detected at the microcrack sections. It was proved that microcracks could be detected by electrical resistance measurement under compression test, whereas the real delamination parts were consistent with the predicted results by electrical resistance measurement.

• Journal of Animal Reproduction and Biotechnology
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• v.38 no.4
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• pp.263-267
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• 2023

Background: Estrus in cows can be detected through vaginal electrical resistance or conductivity. However, there are no studies measuring vaginal electrical resistance in Hanwoo cows. This study aims to measure the vaginal electrical resistance value in Hanwoo cows and compare it with estrus and ovulation. Methods: Vaginal electrical resistance values of 73 Hanwoo cows were measured before and after estrus at the Gyeongsangbuk-do Livestock Research Institute. Measurements were taken on days -6, -3, -2, -1, 0, 1, 2, 3, and 6 of artificial insemination. Large follicles and ovulation were confirmed using transvaginal ultrasonography. Results: The vaginal electrical resistance averaged 225.6 ± 6.3 Ω days before the artificial insemination date, decreasing until the day of artificial insemination. The average vaginal electrical resistance was 163.7 ± 4.6 Ω on the date of artificial insemination, and 188.8 ± 4.3 Ω one day after artificial insemination, when large follicles were observed. In addition, on the 6th day after artificial insemination, the vaginal electrical resistance averaged 231.4 ± 5.5, which was similar to the 6th day before artificial insemination (222.5 ± 6.3). Transvaginal ultrasonography showed that most of the cows ovulated one day after artificial insemination. Conclusions: The accuracy of estrus is high if the vaginal electrical resistance is measured for cows with confirmed estrus, making is a potentially useful for determining the timing of artificial insemination.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.1068-1072
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• 2011

Hydrogen Fuel Cell Vehicle(HFCV) is system that uses electrical energy of fuel cell stack to main power source, which is different system with other vehicles that use high-voltage, large-current. Isolation performance of this system which is connected with electrical fire and electrical shock is important point. Isolation resistance of electric installation is divided according to working voltage, it follows criterion more than $100{\Omega}$/VDC (or $500{\Omega}$/VAC) about system operation voltage in a hydrogen fuel cell vehicle. Although measurement of isolation resistance in a hydrogen fuel cell vehicle is two methods, it uses mainly measurement by megger. However, the present isolation resistance measurement system that is optimized to use in electrical facilities is unsuitable for isolation performance estimation of a hydrogen fuel cell vehicle because of limit of maximum short current and difference of measurement resolution. Therefore, this research developed the isolation resistance measurement system so that may be suitable in isolation performance estimation of a hydrogen fuel cell vehicle, verified isolation performance about known resistance by performance verification of laboratory level about developed system, and executed performance verification through comparing results of developed system by performance verification of vehicle level with ones of existing megger. Developed system is judged to aid estimation and upgrade of isolation performance in a hydrogen fuel cell vehicle hereafter.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.12
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• pp.558-560
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• 2005

The carbon film was deposited by the electrolysis of methanol solution. Carbon films have been grown on silicon substrates using the method of chemical process. From investigations of the Raman spectroscopy and the FTIR spectroscopy, the carbon film deposited by the electrolysis was identified the hydrogenated carbon film with the porous structure. The carbon film deposited by elctrolysis of methanol was identified as the hydrogenated carbon film with porous structure. Deposition parameters for the growth of the carbon films were current density, methanol liquid temperature. We electrical resistance and surface morphology of carbon films formed various conditions specified by deposition parameters. It was clarified that the high electrical resistance carbon films with smooth surface morphology are grown when a distance between the electrodes is relatively wider. We found that the electrical resistance in the films independent of both current density and methanol liquid temperature. The temperature dependence of the electrical resistance in the low resistance carbon films is different from one obtained in graphite..

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.434-436
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• 2000

It is difficult to accurately measure the ground resistance because it varies widely not only with the type of soil but also with the ground parameters; the moisture, the temperature the buried depth of electrodes, and the ground augmentation material and so on. Therefore, in this paper we analyzed the relation between the parameters and the resistance of ground in order to obtain a method of maintaining ground resistance stable. In experiments, the variation coefficients of ground resistance were calculated by the monthly measured data. The ground resistance decreases as the length of the ground rod increases. The variation between the ground resistance and the moisture rate of soil was low in case of using the ground augmentation material. Without the ground augmentation material, the ground resistance decreases as the moisture rate of soil increases. The ground resistance becomes small when the earth temperature becomes low.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1571-1577
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• 2015

A new mixed mode control of constant power and constant current for resistance spot welding inverter is proposed to improve the weld quality. The conventional control scheme adopts constant current or constant power control mode, however, it is not easy to guarantee the high weld quality because of the nonlinear resistance characteristics of the welding point. The proposed method utilizes the nonlinear characteristics by measuring the dynamic resistance in real time. Therefore, it is possible for the welder to be controlled adaptively depending on the welding state. Experimental results show that the proposed control scheme improves the weld quality by 6.8 times compared with the conventional constant current mode control.

• Journal of the Korean Society of Safety
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• v.38 no.1
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• pp.34-41
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• 2023

In this study, S food manufacturing business located in Chungbuk was selected as the subject, and the transition in insulation resistance in major electrical equipment used in this food manufacturing business was analyzed for 4 years (2018-2021). It was confirmed that the insulation resistance decreased over time for all 18 electrical facilities. Insulation resistance changed due to environmental influences such as load characteristics and ambient temperature. Particularly in the case of the food manufacturing industry, it was confirmed that the decrease started after 2 years, although it varied depending on equipment and environmental influences. Furthermore, it was confirmed that management through predicting the management cycle of electrical equipment is possible by deriving a regression equation through regression analysis of insulation resistance measurement values.