• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1861-1863
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• 1996

In this paper, measurements and analyses of ELF electric fields in the vicinity of UHV overhead transmission lines and substations have been conducted. Planar-type sensors have been developed with special consideration of picking up lower frequency and spatial components without any distortion. So finally the electric field measuring system has the frequency bandwidth of 7[Hz] to 2.7[MHz] and the response sensitivity of 0.094[mV/V/m]. A brief description of design rules of the measuring system and measurement procedures is introduced. The actual survey near 154 and 345[kV] overhead transmission lines and power subststions was carried out and analyzed. It may be inferred from these results that the electric field intensity exeeds 7[kV/m] only in very few cases particularly at the substations so that the field measurements meet almost limits or guidelines that various authorized international institutes recommend.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1813-1815
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• 1996

With the three dimensional magnetic field measuring system dealt with in this paper, accurate measurements and analyses of ELF magnetic fields in the vicinity of UHV overhead transmission lines and substations have been conducted. For the field measurements multiturn loop-type sensors have been developed with special consideration of taking lower frequency and spatial components without any distortion. So the measuring system has the frequency bandwidth of 8[Hz] to about 53[kHz] and the response sensitivity of $9.88[mV/{\mu}T]$ in average. A brief description of design rules of the measuring system and measurement procedures is given. The actual surrey near 154 and 345[kV] overhead transmission lines and power subststions was carried out and analyzed. It may be inferred from these results that the maximum magnetic field intensities under typical UHV overhead transmission lines do not exceed $20[{\mu}T]$ so that the field measurements satisfy sufficiently all limits or guidelines that various authorized international institutes recommend.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.119-122
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• 2003

This paper describes characteristics for insertion losses of Isolator have an effect on material parameter. One purpose of the paper is to present insertion loss on this resonator for magnetic loss, dielectric loss, magnetic field and saturation magnetization. Another is to study the effect of propeller resonator on response characteristics. In this paper, the analysis and measurement of the response characteristics were carried out for the isolator prototype. The measurement results agreed on the simulation results and acquire insertion loss $0.18\;{\sim}\;0.24dB$, return loss 27dB, isolation 27dB and bandwidth 500MHz on this condition saturation magnetization 550G, dielectric loss 0.0004, magnetic loss 20 and dielectric constant 14.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2006.06a
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• pp.97-100
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• 2006

A sensor and measuring system were implemented to measure both uroflow and urophonography signal during urination for diagnose the BPH(benign prostatic hypertrophy). The implemented system was composed of the uroflow sensor using the load-cell, the urophonography measurement sensor so as stethoscope type, pre-processing part for sensors signal detection, amplifier and filter, system control parts and PC measurement program. A simulator of the lower urinary system that is experimental equipment implemented for evaluates the developed system. The two signals were measured using implemented system and analyzed these signal by means of time domain and frequency domain for extraction of the characteristic parameter which can most effectively reflected by the occlusion of the lower urinary system. Furthermore two signals were measured and analyzed with the subject of 5 healthy adult for clinical application possibility of the implemented system. As a result, the most influence bandwidth of effect according to occlusion of the lower urinary system is $253{\sim}282Hz$ of the urophonography signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.599-607
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• 2004

In this paper, using phase locked loop(PLL) synthesizer, we introduce a novel but simple and low cost frequency modulation(FM) circuit of a flat peak frequency deviation fur modulation signal whose frequency covers from outside to inside of the loop-bandwidth of PLL. The FM circuit was basically designed to compensate an amount of feedback of the loop filter in PLL. The circuit also includes the capability of the adjustment of peak frequency deviation and of blocking the intereference with the loop filter. The designed circuit was successfully implemented and showed the flat frequency deviation as expected in the design. In addition, the novel measurement method of the wideband FM modulation index is suggested verified With the suggest measurement, it can be successfully shown the designed circuit has the expected frequency deviation.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.304-310
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• 2011

The application of time-domain methods in emission measurement instruments allows for a reduction in scan time by several orders of magnitude and for new evaluation methods to be realized such as the real-time spectrogram to characterize transient emissions. In this paper two novel systems for time-domain EMI measurements above 1 GHz are presented. The first system combines ultra-fast analog-to-digital-conversion and real-time digital signal processing on a field-programmable-gate-array (FPGA) with ultra-broadband multi-stage down-conversion to enable measurements in the range from 10 Hz to 26 GHz with high sensitivity and full-compliance with the requirements of CISPR 16-1-1. The required IF bandwidths were added to allow for measurements according to MIL-461F and DO-160F. The second system realizes a system of time-interleaved analog-to-digital converters (ADCs) and has an upper bandwidth limit of 4 GHz. With the implementation of an automatic mismatch calibration, the system fulfills CISPR 16-1-1 dynamic range requirements. Measurements of the radiated emissions of electronic consumer devices and household appliances like the non-stationary emissions of a microwave oven are presented. A measurement of a personal computer's conducted emissions on a power supply line according to DO-160F is given.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.90-98
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• 1999

Boiler high-temperature pipelines such as main steam pipe, header and steam drum in fossil power plants are degraded by creep damage due to severe operationg conditions like high temperature and high pressure for an extended period time. Such material degradation lead to various component faliures causing serious accidents at the plant. Conventional measurement techniques such as replica method, electric resistance method, and hardness test method have such disadvantages as complex preparation and measurement procedures, too many control parameters, and therefore, low practicality and they were applied only to component surfaces with good accessibility. In this study, both artificial creep degradation test using life prediction formula and frequency analysis by ultrasonic tests for their preparing creep degraded specimens have been carried out for the purpose of nondestructive evaluation for creep damage which can occur in high-temperature pipelline of fossil power plant. As a result of ultrasonic tests for crept specimens, we confirmed that the high frequency side spectra decrease and central frequency components shift to low frequency bans, and bandwiths decrease as increasing creep damage in backwall echoes.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.2
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• pp.31-37
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• 2001

In this paper, We designed and implemented an RF module for WLL multi-channel personal stations. Then, we experimentally evaluated in receiving sensitivity, adjacent channel interference selectivity and spurious response limit. From the measurement results on the RF module for WLL multi-channel personal stations, we observed and confirmed as follows: First, the variation in output power level was kept to be less than 30 dBm in the range of the input power level from -90 dBm to -30dBm. This measurement result confirmed the dynamic range of 60 dB. Secondly, at the output stage of the RF module, the gain flatness in the pass band was measured to be less than 2dB, which confirmed a precise control of the bandspread signals. Thirdly, at the RF module, the bandwidth and power level in transmission were measured to be 10 MHz, respectively we note that these features satisfy the design specifications.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.5
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• pp.607-615
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• 2019

In this paper, the electromagnetic effects on the discontinuity structures of the frequency selective radome in manufacturing process based on the X-band were analyzed. In order to fabricate a curved radome using a planar frequency selective surface structure, it is assumed that gaps, slanted gaps, pattern damage, and pattern misalignment between FSS patterns, which are discontinuous elements that can occur at the joint surface of the FSS panel. FSS specimens including continuous elements were fabricated and the frequency transmission characteristics were measured in a free space measurement environment. From the measurement results, resonance frequency shift, transmission performance degradation, and bandwidth variations were found to be the largest when the damaged pattern was bonded to the junction of FSS panels.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.260-265
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• 2003

A noncontact optical system that can measure displacement or vibration of an object is designed by employing the oblique ray method. By using a single convex lens which serves as both the input and output lenses, we made the optical system very compact and reliable. In addition, the bandwidth of the vibration measurement is more than 100 KHz by using the position-sensitive detector as the beam position sensor. The resolution and capture range of the system are $\pm$1 ${\mu}{\textrm}{m}$ and 1100 ${\mu}{\textrm}{m}$, respectively. As a sample test, the vibrations of a speaker and a rotating compact disc surface were measured.