• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.160-168
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• 2010

This paper presents the analysis of the current as stray current and supplied current of the substation, on the DC railway power system. In DC railway power supply system, the running rails are usually used as the return conductor(negative-polarity) for traction load current. This condition mainly focuses on economic considerations, since it does not require the installation of an additional return conductor. But, problems of low resistance between the running rails for the return conductor and earth allows a significant part of the return load current to leak into the earth. This current is normally called to as leakage or stary current. This stary currents creates serious problems for any electrified matter in the underground. Therefore, reduction of stray current of the DC railway power supply system is also of direct benefit to the operational and safety aspects of the DC railway systems. In this paper, deal with the analysis of the current distribution on the DC railway power system applied the common grounding system, using SPLIT of CDEGS program.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.5
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• pp.388-396
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• 2010

In this study, we propose characteristics improvement methods according to via hole plating method for FBAR Duplexer with bandwidth($T_x4: 1850 MHz ~ 1910 MHz, $R_x$:1930 MHz ~ 1990 MHz) which is used for wireless systems. Also, we designed and fabricated $3.8{\times}3.8{\times}1.8mm$ size microminiature FBAR Duplexer based on this proposal. First of all, in this study, we fabricated pentagon shape resonators by different size to make filter combination, and their quality factor(Q) are 687 with 6.6% of ${k_{eff}}^2$. Using this resonators, we designed $3{\times}2$ Type $T_x$ filter and $3{\times}4$ Type $R_x$ filter. The transmission line, which works as phase shifter, is designed with 210 ${\mu}m$ in width and 18 mm in length Stripline type. Inductor, which is used for matching component, is designed with width of 75 ${\mu}m$, a technically achievable minimum width. And adopted plating method of filling via hole with conductive epoxy for improved grounding and thermal conductivity. Using these configuration with all of the matching component values, we found Duplexer characteristics of -1.57 dB ~ -1.73 dB in insertion loss, -56 dB in attenuation at 1850 MHz ~ 1910 MHz of $T_x$ band. Also, found -2.71 dB ~ -3.23 dB in insertion loss, -58 dB in attenuation at 1930 MHz ~ 1990 MHz of $R_x$ band.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.351-358
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• 2018

In this study, we propose a method of suppressing the leakage noise signal of motor assembly through the test. The motor assembly is mounted on outside of the aircraft to rotate an antenna and must satisfy RE102 requirement on MIL-STD-461F in terms of electromagnetic interference. It is confirmed by RE102 test result hat the leakage noise signal of the equipment occurs due to external influx through the power and control cable and rotation of the motor. And it is ascertained that the part where internal/external physical shielding is difficult to rotate is the leakage path. To reduce the leakage noise signal, the electrical ground reinforcement and the electric shielding structure considering the operation of the equipment is applied and it is verified that the requirement is satisfied. Finally, we verified that required specification are met by applying circular corrugated choke with interlocking shapes and conductive grease to the noise leakage path.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.201-206
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• 2012

The indirect-contact ECG measurement is a newly developed method for unconstrained and nonconscious measurement in daily life. This study introduced a new method of electrode circuit design developed for reducing the 60Hz power line noise observed at the indirect-contact ECG measurement. By the introduced common-mode-driven shielding, the voltage of the electrical shield surrounding the capacitive coupling electrode is maintained at the same as the common mode voltage. Though the method cannot reduce the level of common mode voltage itself, that reduces effectively the differential mode noise converted from the common mode voltage by the difference of cloth impedance between the two capacitive coupling electrode. The experiment results using the actual indirect-contact ECG showed that the 60Hz power line noise was reduced remarkably though the reduction ratio was smaller than the expected by the theory. Especially, the reduction ratio became large for the large difference of cloth. It is expected that the introduced method is useful for reducing the power line noise under condition of poor electrical grounding.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.122-128
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• 2010

This paper presents the characteristics for ground impedance of combined three rods according to distance of current probe and frequency using the fall-of-potential method and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position of auxiliary probes. In order to analyze the effects of ground impedance due to the distance of the current probe and frequency, ground impedances were measured in case that the distance of current probe was located from 5[m] to 20[m] and the measuring frequency was ranged in 55~513[Hz]. The results could be help to determine the position of current probe and the measuring frequency when the ground impedance was measured at grounding system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.96-102
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• 2009

In this paper, the effects of the position and the angle of the potential probes on the measurements of the ground resistance with the fall-of-potential method are described and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position and angle of auxiliary probes. In order to analyze the relative error for measuring value of ground resistance due to the position of the potential probe, ground resistance were measured in case that the distance of current probe was fixed at 50[m] and the distance of potential probe was located from l0[m] to 50[m]. Also, the potential probe was located at 30[$^{\circ}$], 45[$^{\circ}$], 60[$^{\circ}$], 90[$^{\circ}$] and 180[$^{\circ}$]. As a consequence, relative error decreased with increasing the distance of potential probe and decreasing the angle between current probe and potential probe. The results could be help to determine the position of potential probe when the ground resistance was measured at grounding system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.10
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• pp.1364-1370
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• 2014

Power system fault analysis has been based on symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. Obtaining accurate line impedances as possible are very important for estimating fault current magnitude and setting distance relay accurately. Especially, accurate calculation of zero sequence impedance is important because most of transmission line faults are line-to-ground faults, not balanced three-phase fault. Since KEPCO has started measuring of transmission line impedance at 2005, it has been revealed that the measured and calculated line impedances are well agreed within reasonable accuracy. In case of underground transmission lines, however, large discrepancies in zero sequence impedance were observed occasionally. Since zero sequence impedance is an important input data for distance relay to locate faulted point correctly, it is urgently required to analyze, detect and consider countermeasures to the source of these discrepancies. In this paper, development of pre/post processor to ATP (Alternative Transient Program) version of EMTP (Electro-Magnetic Transient Program) for sequence impedance calculation was described. With the developed processor ATP-cable, effects of ground resistance and ECC (Earth Continuity Conductor) on sequence impedance were analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1058-1063
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• 2020

This paper presents a new insulation resistance calculation technique to prevent electric shock and fire accidents due to the dielectric breakdown in the primary insulation section of the IT ground system. The solar power generation market is growing rapidly due to the recent expansion of renewable energy and energy storage systems, but as the insulation is destroyed and fire accidents frequently occur, a device for monitoring the insulation resistance state is indispensable to the IT grounding method. Compared to the conventional algorithm that use a method of multiplying a time constant to a fixed coefficient, the proposed insulation resistance calculation method has a fast response time and high accuracy over a wide insulation resistance range by applying a different coefficient according to the values of the insulation impedance. The proposed dynamic time constant based insulation resistance calculation technique reduces the response time by up to 39.29 seconds and improves the error rate by 20.11%, compared to the conventional method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.10
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• pp.1126-1135
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• 2007

This paper presents the varactor-tuned miniaturized hairpin tunable filter with a single control voltage. The previously proposed miniaturization method is a very straight-forward method to miniaturize a parallel coupled-line filter. In this paper, the miniaturized hairpin tunable filter is proposed with the constant ratio rule of that the capacitances of the each stage always have constant ratio without any dependency to miniaturized electrical length. To show the validity of the proposed method, a 3rd order 0.5 dB ripple Chebyshev fitter with a center frequency of 900 MHz and a fractional bandwidth(FBW) of 10 % was designed and fabricated. The fabricated filter was based on CER-10 substrate of Taconic Inc. with 1SV277 varactor diode of Toshiba Inc. The center frequency of the fabricated filter can be changed from 606 MHz to 944 MHz, 338 MHz with the control voltage from 0.5 V to 4 V. The insertion loss of the proposed filter is increased with the increment of the control voltage, and the filter characteristics are well reserved expect of slight change of the bandwidth with the various control voltage.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.263-270
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• 2008

In this paper, we investigated EMI(electromagnetic interference) reduction by conductor connection, which was used for fixing and electrical grounding between frames. Conductor connects two frames and then it provides the decrease of return path of signal current. To prove the effect of conductor, we measured/simulated the RE(radiated emission) with/without conductors between the two frames. From the measured/simulated results, we observed that EMI decreased about 1$\sim$10 dB at the frequency range of 30 MHz to 1 GHz. VNA(vector network analyzer) was used to measure the S parameters and the RE was measured in a 3 m anechoic chamber. The simulated and measured results are compared and discussed.