• Journal of electromagnetic engineering and science
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• 제18권4호
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• pp.267-269
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• 2018

In this letter, the null steering of a circular array is presented using a modified array factor (AF) for a global positioning system (GPS) anti-jam. The seven radiating elements were designed using a mu-zero resonance (MZR) circularly polarized (CP) antenna arranged toward the center. Since the radiating elements, which are arranged toward the center, have a CP characteristic, the AF of the seven radiating elements has to be modified considering the rotation angle of the nth radiating element. The phases of input ports can be calculated to implement a nulling of radiation patterns where the modified AF is zero. To verify the modified AF for null steering in the desired direction, two cases of power dividers operating in $L_2$ band (1.2276 GHz) were fabricated to achieve pattern nulling at a certain angle. The modified AF can be confirmed by a comparing the simulated and measured radiation patterns.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2004년도 추계 종합학술대회 논문집
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• pp.280-284
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• 2004

안테나의 특성 중 지향성(Directivity)과 관계있는 방사 패턴을 측정하기 위한 저가의 근역장 측정 시스템을 설계한다. 근역장 측정방법은 평면주사법에 기반을 둔 개선된 원통형 주사법 공식을 이용한다. 고가의 측정 장비인 네트워크 분석기를 대체하기 위한 방법을 제시하고 필요한 장치 규격을 제안한다.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.901-906
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• 2007

In this study, we measured the partial discharge phenomenon of inside the closed switchgear, using ultra wide band antenna. The characteristics of $\Phi-q-n$ in the normal state are stable, and confirmed at less than 0.01, but in proceeding states, about 2 times larger. And in the abnormal state, it grew hundreds of times larger compared with normal state. According to K-means analysis, if slant of discharge characteristics is a straight line close to "0" and standard deviation is small, it is in a normal state. However if we can find a peak from K-means clusters and standard deviation to be large, it is in an abnormal state.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.790-793
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• 2001

The characteristics of smart skin for wireless LAN system under compression load are investigated. The smart skin structure is composed of 3 layers of face material and 2 layers of core material. Theoretical formula for determining buckling load is derived by Rayleigh-Ritz method and compared with experimental result. The maximum length of specimen that buckling does not occur is determined by assuming that the compression load is sustained by only face material. In the experiment, if buckling occurs obviously then it follows the theoretical result well. In the process of buckling, the load supporting capability and the antenna property such as radiation pattern and reflection coefficient were examined.

• 전자공학회논문지D
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• 제35D권7호
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• pp.1-8
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• 1998

In this paper, the radiation characteristics of a bar-type tranceiver are analyzed by using FDTD method and the effectiveness of the analysis method is verified by comparing the calculated data with experimental data. The effects of human head and hand on the radiation characteristics of fold-type transceiver are analyzed. In order to observe the effects of human head and hand on the input impedance and far-field radiation pattern, a fold-type transceiver with .lambda./4 monopole antenna wrapped by human hand operating in the proximity of hea dis modeled an analyzed.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.511-514
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• 2003

In this paper, describes the design of PIFA for PDA which has parasitic patch to expand the impedance bandwidth and miniaturization technique to consider the radiation pattern. To expand the impedance bandwidth, generated resonant frequency of parasitic patch is different from that of main patch. To miniaturize the physical dimension, using the folded edge and rectangular slot. The obtained impedance bandwidth is 9.4% ($2.29GHz{\sim}2.515GHz$) at VSWR${\leqq}$2 and antenna gain is 2dBi within the operating frequency.

• 전기학회논문지
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• 제57권2호
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• pp.252-255
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• 2008

A study for discharge pattern analysis partial and fault location by use of UHF sensors in GIS. However, in the latter case, the results considered the velocity of EM waves modified by the waveguide characteristics of GIS bus bar were not reported yet. In this paper, UHF wide band sensor to detect partial discharge signals have been designed and manufactured to get the widest band characteristic by an application of Fat-Dipole UHF antenna and the result that the transmission velocity of EM waves is 2/3 of the light have been got through the consideration of waveguide characteristics. Also, to verify applicability on site of the developed method, self-designed external type UHF sensor have been installed on operating GIS in Korea Midland Power co. and detected location of the fault. Through the fault have been found at the location, the reliability of the developed method have been proved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.33-37
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• 2001

Recently, the HFPD measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Also HFPD testing is able to offer the judgement standard of degradation level of HV machine and can detect discharge signals in live-line. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires live-line diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In recent, the study of partial discharge is carrying out discover of initial defect of power equipment through condition diagnosis and system development of degradation diagnosis using HFPD(High Frequency Partial Discharge) detection. In this study, simulated transformer is manufactured and HFPD occurred from transformer is measured with broad band antenna in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages.

• Journal of Microbiology and Biotechnology
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• 제10권6호
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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.