• 한국전자통신학회논문지
• /
• 제13권1호
• /
• pp.9-14
• /
• 2018

본 연구는 위성중계기용 SHF 대역 IMUX(: Input Multiplexer)의 설계 및 구현에 대해 기술하였다. SHF 대역 입력다중화기는 Combine Filter, 분배기, Isolator 및 Channel Filter로 구성된다. 제작 전 우주환경에 대한 사전 시뮬레이션 분석을 통하여 장비 오동작 가능성을 최소하였으며, 발사환경 시 발생하는 진동에 대한 시뮬레이션을 통해 신뢰성 있는 IMUX를 설계하였으며, 제작 후 주요 성능지표에 대해 만족여부 확인 및 사전 성능 시뮬레이션 결과와 비교하였다.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제11C권2호
• /
• pp.6-11
• /
• 2001

Abstract- In this paper, a new Partial Discharge (PD) detection using Pockels cell was proposed and considerable apparent chaotic characteristics were discussed. For this purpose, PD was generated from needle-plane electrode in air and detecte by optical measuring system using Pockels cell, based on Mach-Zehner interferometer, consisting of He-Ne laser, single mode optical fiber, 50/50 beam splitter and photo detector. In addition, the presence of chaos of the PD signals has been investigated by examining their means of qualitative and quantitative information. For the former, return map and 3-dimensional strange attractor have been drawn in order to investigate the presence of chaotic characteristics relevant to PD signals, detected through CT and Peckels sensor respectively, in the normalized time series. The presence of strange attractor indicates the existence of fractal structures in it's phase space. For the latter, several dimension values of strange attractor were verified sequentially. Throughout this paper, it is likely that the chaotic characteristics regarding the PD signals under air are verified.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제11권4호
• /
• pp.238-246
• /
• 2011

A 3-5 GHz UWB radar chip in 0.13 ${\mu}m$ CMOS process is presented in this paper. The UWB radar transceiver for surveillance and biometric applications adopts the equivalent time sampling architecture and 4-channel time interleaved samplers to relax the impractical sampling frequency and enhance the overall scanning time. The RF front end (RFFE) includes the wideband LNA and 4-way RF power splitter, and the analog signal processing part consists of the high speed track & hold (T&H) / sample & hold (S&H) and integrator. The interleaved timing clocks are generated using a delay locked loop. The UWB transmitter employs the digitally synthesized topology. The measured NF of RFFE is 9.5 dB in 3-5 GHz. And DLL timing resolution is 50 ps. The measured spectrum of UWB transmitter shows the center frequency within 3-5 GHz satisfying the FCC spectrum mask. The power consumption of receiver and transmitter are 106.5 mW and 57 mW at 1.5 V supply, respectively.

• 한국입자에어로졸학회지
• /
• 제13권4호
• /
• pp.159-164
• /
• 2017

The detection efficiency and characteristics of an optical particle counter (OPC), with various sample nozzle outlet diameters, were experimentally investigated. The OPC system, which was built with original design, was made up of a diode laser, two photodetectors, and a variety of optics such as a beam splitter and a concave mirror. The cone-shaped sampling nozzle was designed to be changeable to alter the outlet diameter, within the range of 1 to 3 mm. For samples, sets of polystyrene latex (PSL) standard particle with various sizes of 1 to $3{\mu}m$, were used. As a result, detection efficiency of the OPC greatly decreased with larger nozzle outlet diameter. Moreover, increased nozzle outlet diameter means broader sample flow, thus caused light interference and multiple scattering which results in abnormal high peaks in scattered light signal. The ratio of abnormal peaks to regular signal of single particle increased with larger nozzle outlet diameter.

• 조명전기설비학회논문지
• /
• 제29권12호
• /
• pp.1-7
• /
• 2015

In this paper, we propose a second-order fiber flexible comb filter based on a polarization-diversity loop(PDL). The proposed filter consists of a polarization beam splitter, four half-wave plates(HWPs), and three high birefringence fiber(HBF) segments. In the previous Solc-type second-order filter based on the PDL, HBF segments were fusion-spliced with a fixed angle offset between their principal axes with each other. But, the proposed filter implemented by inserting two HWPs between three HBF segments has a great flexibility in adjusting relative angular difference between the principal axes of two adjacent HBF segments. Owing to this flexibility, second-order transmission spectra, which had a channel spacing of ~0.8nm, could be interleaved by controlling the orientation angles of four HWPs. The output transmission spectra of the proposed filter were theoretically analyzed and experimentally verified.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1850-1852
• /
• 2000

In this paper, new Partial Discharge (PD) detection technique using Pockels cell was proposed and considerable apparent chaotic characteristics were discussed. For this purpose, PD was generated from needle-plane electrode in air and detected by optical measuring system using Pockels cell, based on Mach-Zehnder interferometer, consisting of He-Ne laser, single mode optical fiber, 50/50 beam splitter and photo detector. A qualitative analysis was carried out by drawing Return map for the normalized time series of the detected PD signals. The results are as follows:(a) Fixed points, between 0.7 and 1.0, are appeared clearly in the right upper area of the return map as the increase in the number of obtained data.(b) Considerable periodicity have been remarked even though exact period and length can not be determined.(c) The self-similarity can be also observed inasmuch as the late paths do not follow the previous ones. Accordingly, exact quantitative analysis such as embedding dimension, fractal dimension, and Lyapunov exponents should be carried out for deducing the quantitative properties regarding PD phenomena.

• 한국광학회지
• /
• 제26권1호
• /
• pp.38-43
• /
• 2015

반사도 가변형 출력경을 갖는 긴 공진기형 선편광 Yb:YAG 레이저를 제안하고 그 출력 특성을 조사하였다. 반사도 가변형 출력경은 편광 광 분할기와 1/4 파장판로 구성되어 있다. 제안된 레이저 공진기 길이는 약 3.7 m 이다. 제안된 레이저의 기울기 효율은 19%이고 빔질 ($M^2$)는 약 1.2이었다.

• Wind and Structures
• /
• 제16권5호
• /
• pp.517-540
• /
• 2013

This paper presents applications of proper orthogonal decomposition in both the time and frequency domains based on both cross spectral matrix and covariance matrix branches to analyze multi-variate unsteady pressure fields on prisms and to study spanwise and chordwise pressure distribution. Furthermore, modification of proper orthogonal decomposition is applied to a rectangular spanwise coherence matrix in order to investigate the spanwise correlation and coherence of the unsteady pressure fields. The unsteady pressure fields have been directly measured in wind tunnel tests on some typical prisms with slenderness ratios B/D=1, B/D=1 with a splitter plate in the wake, and B/D=5. Significance and contribution of the first covariance mode associated with the first principal coordinates as well as those of the first spectral eigenvalue and associated spectral mode are clarified by synthesis of the unsteady pressure fields and identification of intrinsic events inside the unsteady pressure fields. Spanwise coherence of the unsteady pressure fields has been mapped the first time ever for better understanding of their intrinsic characteristics.

• 조명전기설비학회논문지
• /
• 제27권3호
• /
• pp.1-6
• /
• 2013

In this study, we propose a fiber-optic hydrogen sensor using a polarization-diversity loop configuration composed of a polarization beam splitter, two quarter-wave plates, and a polarization-maintaining fiber coated with palladium whose thickness is ~400nm. One transmission dip of the output interference spectrum of the proposed sensor, chosen as a sensor indicator, was observed to spectrally shift with the increase of the hydrogen concentration, and the sensing indicator showed a wavelength shift of ~2.48nm at a hydrogen concentration of 4%. Except for a hydrogen concentration of 4%, the response time of the proposed sensor was measured as less than 12.5s and did not show significant dependence on the hydrogen concentration. In particular, the proposed fiber hydrogen sensor is more durable and highly resistant to external stress applied on a transverse axis of an optical fiber, compared with other hydrogen sensors based on side-polished fibers or fiber gratings.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.1273-1274
• /
• 2007

In this paper, a Optical Voltage Transformer has been designed and fabricated to improve temperature stability caused by materials properties and insulation in measuring system, using single crystal $Bi_{12}SiO_{20}$ as Pockels effect cells for Gas Insulated Switchgear[GIS] System. LD[wavelength: 850nm] was used as optical source, InGaAs as optical detector to measure optical power, Polarizing Beam Splitter as Polarizer and Analyzer, and Multi-mode Optical-fiber[62.5/$125{\mu}m$] as Light transmission line. OPT was assembled in order to pockels effect, and adopted direct electric field type. The linearity of OPT maintains variation for applied voltage range from 100V - 3000V during the test of electric property, As the temperature was changed from $25^{\circ}C$ to $60^{\circ}C$. the result of this study shows that characteristics of OPT are good, and it can be reflected for practical optical sensors in GIS system.