• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.91-96
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• 2014

Modern electronic circuits are becoming more vulnerable to damage by surges, and it is required to improve the impulse withstand voltage performance of electrical and electronic equipment. This paper presents the impulse withstand voltage performance of lighting equipment connected to power lines, and the impulse withstand voltage tests for fluorescent lamp, LED lamp and halogen lamp were carried out according to the reference standards under normal service conditions. To conduct performance tests against lightning surge, a combination wave ($1.2/50{\mu}s$ voltage - $8/20{\mu}s$ current) was employed. The test surge was applied between lines or between line and ground of the specimen to be measured. The test surge was applied synchronized at the peak value of the positive and negative AC voltage waves. As a consequence, some specimens satisfied the impulse withstand voltage test criteria, but lighting equipment such as 36W fluorescent lamps, 5W and 5.5W LED lamps and 50W halogen lamp were damaged at the test voltage levels between power lines. It is needed to improve the qualities of lighting equipment to satisfy EMC immunity requirements of equipment for general lighting purposes.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.917-921
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• 1991

Hydraulic fitting impulse tester is equipment which produce impulse pressure waveform that specified foreign standard of SAE, JIS etc. Test conditions of SAE J1453 about waveform standard indicates frequency of 35-70 cycle/min, pressure of 560 bar, oil temperature of 93 .+-.3.deg. C etc. and required cycle is a million over. In additions, Test condition operated continuously equipment. This development item adopted new pattern method such as intensifier and rotary distributor is different from already established fitting impulse tester applied servo valve and high pressure direct directional control valve. Therefore, this development item which compares already established item is good reliability, low cost of manufacture and save of electric energy. especially, Domestic small and medium enterprise uses this tester because of economical cause. We develope appropriateness tester which conforms to demand of user.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.24-32
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• 2011

[ $SF_6$ ]gas, which has an excellent dielectric strength and interruption performance, is used in various applications such as gas insulated switchgear (GIS) in substations. However, since $SF_6$ has a high global warming potential (GWP), it is necessary to find an eco-friendly alternative insulation gas. In order to examine the possibility of using alternative insulation gases for $SF_6$ in power distribution system equipment, the dielectric strength and physical phenomena of dry air in a quasi-uniform electric field are investigated experimentally in this paper. As a result, the breakdown voltages for positive polarity are higher than those for negative polarity under impulse voltage applications. The negative 50[%] flashover voltage, $V_{50}$ of dry air under conditions above 0.4[MPa] gas pressure, is higher than 150[kV], that is the basic impulse insulation level of distribution equipment. The $V_{50}$ increases linearly with increasing the gas pressure, regardless of the waveform and polarity of the applied impulse voltages. The voltage-time curves are dependent on the rise time of the impulse voltage and gas pressure. Furthermore, streamer discharge was observed through light emission images by an ICCD camera under impulse voltage applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.142-149
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• 2010

This paper describes dielectric characteristics of $SF_6$ and dry-air gases under lightning impulse voltages in a quasi-uniform electric field. In order to simulate to a quasi-uniform electric field, electric field utilization factor of the used sphere-plane electrode is 71[%]. The gas pressure of $SF_6$ ranges from 0.1 to 0.2[MPa] and that of dry-air ranges from 0.2 to 0.6[MPa]. Electrical breakdown voltages of $SF_6$ and dry-air gases are measured and analyzed as functions of the polarity of lightning impulse voltage and gas pressure. As a result, the electrical breakdown voltage of both gases under the positive lightning impulse voltage is higher than that under the negative one. The electrical breakdown voltage in $SF_6$ is almost higher than 2.67 times compared to dry-air. The results presented in this paper can be used as a useful information to evaluate the capability of alternative insulation gases for $SF_6$ in power distribution equipment with prominent ability against lightning surge.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1633-1635
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• 1994

This paper presents the development technology of standard resistor divider for full lightning impulse voltage. The ability of high voltage bulk power equipment to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently International standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisions have been completed already worldwide, i.e. Europe, Japan, America etc.. In this viewpoint, we have also investigated the standard resistor divider with shield, which satisfies the IEC recommendation.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.927-934
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• 2015

In this paper, in order to prevent impulse surge PoE(Power Over Ethernet) communications error caused by natural phenomenon in industrial sites, countermeasure design of impulse surge of PoE communications equipment is suggested by designing dual impulse surge protection circuit. In order to analyze characteristic of impulse surge noise signal, surge generating device which meet international standard IEC 61000-4-5 is invented. And this device shows that surge signal is weakened by designing dual PoE power supply protection circuit by connecting surge generating device to the PoE data transfer line.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.4 no.2
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• pp.1-8
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• 2005

In this paper, n system did research about effect that interference effect with neighborhood single equipment or group equipment gets in DMB service. For this, 2.6425 GHz SDMB(Satellite Digital Multimedia Broadcasting) that a special of electric wave interference is near frequency-band including interference of signal by unnecessary radiation level that is radiated in UWB system, and degree of 3.4125GHz broadcasting relay net that is In-band frequency-band and interference effect that get in service analyzed comparison ud, modulation of broadcasting relay net and interference measurement equipment used Impulse and OFDM methods. Impulse method was $BER=1{\times}10^4$ that broadcasting signal receiption is possible at 1.4m point because interference effect happens from 2m point in SDMB system, and it was $BER=1^{\times}10-4$ that OFDM method receives interference effect from 0.8m point and broadcasting signal receiption is possible at 0.5m point. Also, about gap-filler center frequency, in case of space interval more than 0.01m, there was no interference effect. Therefore, for the electric wave of W system that is small output applies to system without interference effect in DMB service, confirmed that UWB system of OFDM method is less interference effect than UWB system of impulse method.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.7 no.1
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• pp.23-31
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• 2007

In this paper, UWB system did research about effect that interference effect with neighborhood single equipment or group equipment gets in broadcasting communication service. For this, 2.6425GHz SDMB(Satellite Digital Multimedia Broadcasting) that a special of electric wave interference is near frequency-band including interference of signal by unnecessary radiation level that is radiated in UWB system, and degree of 3.4125GHz broadcasting relay net that is In-band frequency-band and interference effect that get in service analyzed comparison and, modulation of broadcasting relay net and interference measurement equipment used Impulse and OFDM methods. Impulse method was $BER\;=\;1{\times}\;10^{-4}$ that broadcasting signal receiption is possible at 1.4m point because interference effect happens from 2m point in SDMB system, and it was $BER\;=\;1{\times}\;10^{-4}$ that OFDM method receives interference effect from 0.8m point and broadcasting signal receiption is possible at 0.5m point. Also, about Gap-Filler center frequency, In case of space interval more than 0.01m, there was no interference effect. Therefore, for the electric wave of UWB system that is small output applies to system without interference effect in broadcasting communication service, confirmed that UWB system of OFDM method is less interference effect than UWB system of Impulse method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.2
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• pp.118-127
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• 2018

In this work, we have designed and manufactured radar target simulation equipment for the performance analysis of synthetic aperture radar(SAR) systems. First, we have explained the function and performance specification of the target simulation equipment and point target scenario generation for validation of the SAR system. In addition, we have developed a simple and accurate calibration method for the time delay of the SAR system using the manufactured target simulation equipment. We have analyzed the point target impulse response function of the SAR image acquired using the SAR system and the target simulation equipment. It was observed that the measured peak to side lobe ratio(=-13.25 dB) and resolution(=0.49 m) are in good agreement with the corresponding theoretical values.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.499-516
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• 2007

An experimental method denoted as Impulse Method is proposed as a cost-effective non-destructive technique for the on-site evaluation of concrete elastic modulus in existing structures: on the basis of Hertz's quasi-static theory of elastic impact and with the aid of a simple portable testing equipment, it makes it possible to collect series of local measurements of the elastic modulus in an easy way and in a very short time. A Hypothesis Testing procedure is developed in order to provide a statistical tool for processing the data collected by means of the Impulse Method and assessing the possible occurrence of significant variations in the elastic modulus without exceeding some prescribed error probabilities. It is based on a particular formulation of the renowned sequential probability ratio test and reveals to be optimal with respect to the error probabilities and the required number of observations, thus further improving the time-effectiveness of the Impulse Method. The results of an experimental investigation on different types of plain concrete prove the validity of the Impulse Method in estimating the unknown value of the elastic modulus and attest the effectiveness of the proposed Hypothesis Testing procedure in identifying significant variations in the elastic modulus.