• 대한원격탐사학회지
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• 제26권2호
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• pp.65-73
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• 2010

구름과 강수특성을 분석하기 위해 대관령에 구름물리관측시스템(Cloud physics Observation System, 이하 CPOS)을 2003년부터 운영해 오고 있다. 주요 관측 기기는 다음과 같다: FSSP (Forward Scattering Spectrometer Probe), OPC (Optical Particle Counter), VS (Visibility Sensor), PARSIVEL disdrometer, MWR (Microwave Radiometer), MRR (Micro Rain Radar). 앞의 4개 장비는 지상구름 (안개)과 강수 특성을, 뒤의 2개 장비는 연직구름의 특성을 실시간으로 관측하고 있다. CPOS 산출물을 검증하기 위해 FSSP는 흡습성 물질 시딩 실험 중 OPC와, MWR의 가강수량은 라디오존데와, PARSIVEL과 MRR은 우량계와 비교 연구가 수행되었다. 그 결과를 보면 대부분이 0.7이상의 좋은 상관도를 보인다. 이와 같이 신뢰도를 확보한 CPOS 관측 자료는 구름과 에어로솔의 간접효과나 기상조절 실험에 유용한 자료로 활용될 수 있을 것이다. FSSP의 입자 크기 분포를 시정값으로 환산해 보았으며 FSSP 환산 시정값은 visibility sensors (SVS)와 PWD22 (Present Weather Detect 22)의 시정계 값에 비해 1.7~1.9배 과도한 경향을 보였다. 이는 FSSP에 의해 관측되는 입자 크기($2{\sim}47\;{\mu}m$)의 한계 때문으로 사료된다. 향후 다른 입자크기분포를 측정할 수 있는 장비를 도입하여 추가 분석을 추진할 계획이다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1002-1004
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• 2003

A ground-based, C-band full polarimetric mobile Scatterometer system has been developed in Malaysia with collaboration between Malaysian Centre for Remote Sensing (MACRES) and Multimedia University (MMU). The main purpose of this system is to measure and monitor backscattering coefficient, ${\sigma }^0$, for earth terrain such as paddy fields, forest and soil surfaces. This paper describes the preliminary results on radar backscatter measurement from paddy field using the mobile C-band Scatterometer system. The measurement campaign was conducted at Sungai Burung area in April 2003. Real time data were collected using four polarization modes (HH, HV, VV and VH), at various incidence angles ranging from 0$^0$ to 60$^0$. The measurement data show consistent results as compared to other reports, which verify the capability of this Scatterometer system as a useful tool for remote sensing.

• Journal of information and communication convergence engineering
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• 제16권1호
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• pp.12-16
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• 2018

In this work, a voltage controlled oscillator (VCO) monolithic microwave integrated circuit (MMIC) was demonstrated for 10-GHz band motion detecting sensors. The VCO MMIC was fabricated using a $2-{\mu}m$ InGap/GaAs HBT process, and the tuning of the oscillation frequency is achieved by changing the internal capacitance in the HBT, instead of using extra varactor diodes. The implemented VCO MMIC has a micro size of $500{\mu}m{\times}500{\mu}m$, and demonstrates the value of inserting the VCO into a single chip transceiver. The experimental results showed that the frequency tuning characteristic was above 30 MHz, with the excellent output flatness characteristic of ${\pm}0.2dBm$ over the tuning bandwidth. And, the VCO MMIC exhibited a phase noise characteristic of -92.64 dBc/Hz and -118.28 dBc/Hz at the 100 kHz and 1 MHz offset frequencies from the carrier, respectively. The measured values were consistent with the design values, and exhibited good performance.

• 전기학회논문지
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• 제56권12호
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• pp.2196-2201
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• 2007

Materials used at microwave are usually used as a dielectric with a manufacturing purpose of printed circuit boards, etc. Complex permittivity of them can be measured from attenuation constant or propagation constant of a transmission line using a microstrip line with bulk type. But as the technique recently which can manufacture to have complex permittivity and permeability demanded using nonferrous metals for powder-type grows up, we need sensors and methods which can measure characteristics of powder-type materials. So far measuring methods of permittivity and permeability with waveguide or coaxial cable are used but they have faults which have a complex measurement method and are difficult to simultaneously measure permittivity and permeability. In this paper, a simultaneous measuring method of permittivity and permeability with 2-port coaxial cable and a new proposed calculation. The proposed 2-port coaxial cable is designed to be easy to insert materials and to have a wideband. We measure permittivity and permeability of magnetic powder(Ni-Fe-Mo, Ni-Fe) which reveal its characteristic at $0.3{\sim}1.3GHz$ to identify the proposed sensor.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.38-42
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• 1999

Using the LOCOS process, we have fabricated the lateral type polysilicon field emission triodes with poly-Si/oxide/Si structure and investigated their current-voltage characteristics for three biasing modes of operation. The fabricated devices exhibit excellent electrical performances such as a relatively low turn-on anode voltage of 14 V at VGC = 0V, a stable and high emission current of 92${\mu}$A/triode over 90 hours, a small gate leakage current of 0.23 ${\mu}$A/triode and an outstanding transconductance of 57${\mu}$S/5triodes at VGC = 5V and VAC = 26V. these superior electrical operation is believed to be due to a large field enhancement effect, which is related to the sharp cathode tips produced by the LOCOS process as well as the high aspect ratio (height /radius ) of the cathode tip end.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.37-42
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• 1998

Latent and sensible heat fluxes over the global oceans are estimated using SSM/I (Special Sensor Microwave Imager) and AVHRR MCSST (Advanced Very High Resolution Radiometer Multi-Channel Sea Surface Temperature). The heat fluxes are computed from SSM/I wind speeds and surface humidity, the MCSST, and NCEP Reanalysis sea level pressures and 2-m temperatures from 1996 to 1997. The diabatic conditions bulk formula (Kondo, 1975) is used to compute the heat fluxes. To validate, the derived fluxes are compared to the measurements of 3 JMA buoys. The wind speeds and surface humidity derived from SSM/I have accuracies of 1.37m/s and 1.7g/kg, respectively. The heat fluxes were estimated these factors and the standard error of the latent and sensible heat fluxes are 5.53 W/m$^2$ and 3.33 W/m$^2$. The latest El-Nino phenomenon started at the beginning of 1997 and this event was larger than any others. We compare the heat fluxes in 1997 with the fluxes in 1996 and investigate the spatial movement of meteorological factors as well as the heat fluxes associated with El-Nino appearance.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.644-648
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• 2002

Though it was difficult of globally monitor latent heat flux aver the ocean for many years, the situation is rapidly changing by the use of satellite data. Since a bulk formula is used to estimate turbulent heat flux using satellite data, we need wind speed, sea surface temperature and specific humidity data. However, it is not easy to accurately estimate specific humidity using satellite data. Now several algorithms for estimating specific humidity have been proposed and applied to construct latent heat flux data sets. Latent heat flux data sets derived from satellite data such as J-OFURO, HOAPS and GSSTF are available at present. Since the algorithm and used satellite data are not the same between them. the characteristics of each data set may be different. Therefore, it is important to clarify the difference between each data set and investigate the cause of the difference in latent heat flux estimates. In this paper we summarize the present state of the art with regard to the turbulent heat flux estimation by using satellite data. Also we present the comparison results of latent heat flux fields including not only satellite-derived flux fields but also analysis fields.

• 대한교통학회지
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• 제19권6호
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• pp.171-182
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• 2001

본 연구는 지점검지체계와 구간검지체계와의 자료합성을 통하여 도심 간선도로 및 지방도로 구간별 효과척도를 산정할 뿐만 아니라 유고검지 및 통행패턴 예측, 네트워크 기종점에 대한 최적/최단 경로를 탐색하는데 기초가 되는 구간 통행시간 추정을 수행한다. 개개 수집원의 자료합성을 위해 퍼지이론과 인공신경 망의 합성모형인 FALEM(Fuzzy Adaptive Learning Estimator for travel time from Multi-information sources)을 개발, 개발된 모형 FALEM에 의해 개개구간의 통행시간을 산출하고 동일시간, 동일구간에서 조사된 실측데이터와의 오차율 비교를 통해 추정된 통행시간을 검증하였다. 테스트 환경은 개발모형에 의해 추정된 구간 통행시간의 적용성을 고려하여 실시간 운영하에서 수행되었다.

• 한국산학기술학회논문지
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• 제18권2호
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• pp.472-477
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• 2017

기름 유출로 인한 피해는 수질환경 및 생태계를 단시간에 파괴할 뿐만 아니라 한번 오염이 되면 회복하는데 상당한 시간이 걸리고 회복이 어려우며, 지속적으로 나타난다. 때문에 해양이나 하천, 담수 등의 기름유출을 모니터링할 수 있는 오일 검출기의 필요성이 매우 높다. 오일을 검출할 수 있는 기술로는 크게 접촉식과 비접촉식으로 구분할 수 있으며, 접촉식으로는 Conductivity, Capacitance, Microwave 등이 있고 비접촉식으로는 Infrared, UV, Laser, Optic, Radar 등으로 구분할 수 있다. 수면 위에 있는 오일을 측정하기 위해서는 파고 및 너울, 빛의 산란, 온도, 염도 등 여러 가지 관측의 장애가 존재하기에 측정하고자 하는 환경에 맞는 오일 검출기를 선택하여 사용해야 한다. 본 논문에서는 접촉식 방식으로 정유회사 및 유화회사, 발전소 등의 오일 관련 업종에서 사용할 수 있는 오일 검출기를 구현하였다. 장비의 구성은 수면 위에 띄워 놓는 센서 모듈과 센서 모듈에서 들어오는 신호를 가공하여 표시하는 제어기로 구분하며, 센서를 통하여 오일의 유무를 판별하고 더 나아가 오일의 양과 오일의 종류에 따른 유전율의 변화를 관측하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.65-65
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• 2002

In remote sensing, images are acquired over the same area by sensors of different spectral ranges (from the visible to the microwave) and/or with different number, position, and width of spectral bands. These images are generally partially redundant, as they represent the same scene, and partially complementary. For many applications of image classification, the information provided by a single sensor is often incomplete or imprecise resulting in misclassification. Fusion with redundant data can draw more consistent inferences for the interpretation of the scene, and can then improve classification accuracy. The common approach to the classification of multisensor data as a data fusion scheme at pixel level is to concatenate the data into one vector as if they were measurements from a single sensor. The multiband data acquired by a single multispectral sensor or by two or more different sensors are not completely independent, and a certain degree of informative overlap may exist between the observation spaces of the different bands. This dependence may make the data less informative and should be properly modeled in the analysis so that its effect can be eliminated. For modeling and eliminating the effect of such dependence, this study employs a strategy using self and conditional information variation measures. The self information variation reflects the self certainty of the individual bands, while the conditional information variation reflects the degree of dependence of the different bands. One data set might be very less reliable than others in the analysis and even exacerbate the classification results. The unreliable data set should be excluded in the analysis. To account for this, the self information variation is utilized to measure the degrees of reliability. The team of positively dependent bands can gather more information jointly than the team of independent ones. But, when bands are negatively dependent, the combined analysis of these bands may give worse information. Using the conditional information variation measure, the multiband data are split into two or more subsets according the dependence between the bands. Each subsets are classified separately, and a data fusion scheme at decision level is applied to integrate the individual classification results. In this study. a two-level algorithm using hierarchical clustering procedure is used for unsupervised image classification. Hierarchical clustering algorithm is based on similarity measures between all pairs of candidates being considered for merging. In the first level, the image is partitioned as any number of regions which are sets of spatially contiguous pixels so that no union of adjacent regions is statistically uniform. The regions resulted from the low level are clustered into a parsimonious number of groups according to their statistical characteristics. The algorithm has been applied to satellite multispectral data and airbone SAR data.