• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.151-156
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• 2003

Millimeter waves are potentially useful for high resolution ranging and imaging in low optical visibility conditions such as fog and smoke. Also, They can be used for wide band communications since the currently used spectrum bands are already crowded. However, it is necessary to develop a theoretical and experimental understanding of millimeter wave propagation to assess the performance of millimeter wave systems. The intensity fluctuations and mutual coherence function (MCF) describe atmospheric effects on the millimeter wave propagation. Using the quasi-optical method (QOM), a practical and efficient method is suggested to obtain MCF from the flux measurement in the antenna focal plane.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.372-384
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• 2014

DTV field tests have been performed to measure field strength and to check reception ratio on indoor and outdoor sites. They use an antenna of 9m to measure DTV signal in case of outdoor measurement on the road. Modern skyscrapers require the analysis of vertical-directional wave propagation by measuring vertical-directional DTV signal. Even if the field strength is above the reception threshold of $43dB{\mu}V/m$, the reception is impossible in case of strong multi-path or high impulse noise. So, vertical-directional field measurement is essential in environment of tall buildings. In this paper, we developed an octo type multi-copter to measure vertical-directional DTV signal level. A compact and portable DTV signal level meter, an antenna, a microwave transmitter for data transmission, and a recording equipment are equipped in the multi-copter. Three different sites are selected to test the measurement system. Developed measurement system using the multi-copter is very useful in measuring vertical-directional DTV signal, especially in apartments, non-accessible area by vehicles, and forbidden areas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.318-327
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• 2017

It is essential for the near-field receiving measurement to make beam pattern and check the performance of a active phased array antenna system. Also, we could obtain compensation value for mono-pulse function through the near-field receive test, however, if the radar has many frequency channel, the test would take long time and hard effort. So it is needed that frequency channels are selected for measurement and calculates the values for other frequency channels to improve efficiency in development and manufacture. In this case, the phase variations in sum and del channels would be checked. The phase measurement includes un-linear characteristic because of wrapping effect. Generally, radars have similar path length in sum and del channel, but if a radar has a electrical length gap between sum and del channel, errors could occur by phase's wrapping effect. In this paper, the interpolation method's error caused by electrical length gap is checked and the effective method for frequency channel selection to avoid wrapping effect is introduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.499-504
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• 2017

A Mobile Radio Wave Measurement System (MRWMS)is a vehicle-mounted system designed to be operating in a single mission. The mission characteristic for mobile measurement requires mobility. For this, we must consider the arrangement and embedded method of MRWMS's antennas. In this paper, we described the measurement method design of direction detecting accuracy for MRWMS and designed the direction finding antenna mast capable of rotating itself by using a slip ring without turntable for Direction Finding (DF) accuracy test. As we removed the dependency of a limited local area by designing a measurement method of direction detecting accuracy, Equipment Under Test (EUT) zero-Adjustment and mounted process shortened. So, we the reduced production costs. We expect an improved cable loss value by shortening the RF cable length in accordance with our design. In addition, due to the same phenomenon, the entire system is lighter and the mobility is improved.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.47-52
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• 2006

In recent years, there is a strong urge to introduce GPS systems which can role in reference points and measure global positions to the field of structural measurements. In this study, a new structural measurement system using low-cost L1 single frequency GPS receivers instead of conventional expensive RTK L1&L2 dual frequency GPS receiver. This system consists of GPS OEM board, GPS antenna, wireless access points, and monitoring program based on Lambda method and makes it possible to apply to monitor a static behavior of large scaled Infra-structures, such as dams, tall buildings, road slops.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1698-1700
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• 2002

Recently, the HFPD measurement methods that detect high frequency bandwidth of frequency components of partial discharge pulses are proposed and many studies are carried out. The HFPD measurement method is able to detect partial discharge signal in active line, therefore this method has a merit that can does condition monitoring of power equipments and measure growth state of partial discharge erosion with on-line and real time. In this study, the radiated HFPD signals are detected by antenna and aging diagnosis is executed with a neural network algorithm. As a result of this study, the aging diagnosis of insulation material using neural networks is possible.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.900-903
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• 2014

Fly-wheel, Gimbal antenna, CMG, Spaceborne cyrocooler generate micro-vibration during their on-orbit operation as well as implementing their own function. To comply with the mission requirement of high resolution observation satellite, additional technical efforts have been required to isolate the micro-vibration derived from such payloads by applying the vibration isolator. In this study, we proposed a passive isolator using SMA mesh washer, which guarantees the structural safety of both micro-vibration disturbance source and itself under harsh launch vibration loads without an additional holding mechanism and the micro-vibration isolation performance on orbit environment. To verify the micro-vibration isolation performance of the proposed vibration isolator, we performed the micro-vibration isolation measurement test using the dedicated micro-vibration measurement device proposed in this study.

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.885-888
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• 2000

Electroantennogram(EAG) can be applied to detect odorants since insects have highly specialized olfactory receptors inside their antennae. The characteristics of EAG parameters were investigated for the quantitative measurement of a general odorant using ammonia as a model odorant. The antennae of male silkworm moth, Bombyx mori, were used for the EAG. The electical signal curves generated from a pair of antennae originating from the same silkworm moth were never identical; however, they exhibited a typical type I or type II characteristic curve pattern for every pair of antennae. The correlation between the EAG parameters and the ammonia concentration was analyzed for the type I and type II antennae. The stability of each parameter was also investigated for each type of antenna. The results show the possibility of the quantitative measurement of general odorants using the EAG technique.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.204-205
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• 2007

We have developed a new measurement system by using GPS to complement those errors. In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly-stable clock. The GPS mounted on the roof of TT4 in KHST receives a signal from the RS232 communication port, and it is connected to the network system in TT3 after converting with TCPIP communication. It is able to track the position of vehicle and synchronize the signal from different measurement system simultaneously. Therefore it is able to chase the fault occurrence, track inspection and electrical interruptionat real-time situation more accurately. There is not an error coursed by vehicle conditions such as slip and the slide.

• Journal of the Korean Institute of Navigation
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• v.19 no.1
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• pp.9-16
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• 1995

We are confronted with the serious EMI(electromagnetic interference) problems in company with the development of electronic equipments. Accordingly it is also required to construct some anechoic chambers for EMI measurement. Furthermore it is very important to evaluate the chamber characteristics in advance of its construction. For that purpose we have analyzed the characteristics by computer simulation in base on the image method, and compared the results with the measured ones. In case of 3-meter method as a result, the curved line of height pattern of open site varies similarly as that of height pattern of anechoic chamber. When we measure the electromagnetic strength and can get the height pattern curves by frequencies, we utilized it effectively because we can protect instrumental errors in measurement. On the other hand, there is a little difference in site attenuation above 700MHz. When the ferrite grid was used however, the calculated values agree well with the measured values up to 1000MHz with the exception of 30-40 MHz range. The reason is that we don't consider the antenna coupling in the low frequencies of 30-100MHz range.