• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.34-37
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• 2008

물체의 움직임을 감지하는 이동물체 식별용 센서로는 적외선 센서, 초음파 센서, 마이크로파 센서 등이 많이 사용되고 있다. 본 논문에서는 감도가 우수하면서도 간단한 구조로 가격을 최소화하여 제품의 경쟁력을 최대화한 마이크로파 센서를 개발하였으며, 실제 시제품으로 제작하여 그 특성을 확인한 결과 우수한 특성이 나타남을 확인되었다. 본 연구진은 개발된 센서의 특성 확인 결과로부터 다음과 같은 두 가지 효과가 있는 것으로 판단하고 있다. 첫째, 제품의 성능은 유지하면서 간략한 구조를 갖는 회로의 구성은 제조 원가를 줄일 수 있으므로 충분한 제품 가격 경쟁력을 갖을 것으로 생각된다. 둘째, 간략한 구조를 갖는 회로의 구성은 제품의 소형화, 경량화를 가능케 하는'효과도 있을 것이다.

• Proceedings of the KSRS Conference
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• v.2
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• pp.997-1000
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• 2006

We estimate the net heat flux in the tropical and subtropical Atlantic Ocean using satellite data. These fluxes are related to changes in sea surface temperature (SST). This variable influences atmospheric circulations and is indicative of surface and subsurface oceanic circulations. We employ data from the geostationary METEOSAT-7 and 8 satellites and from the Special Sensor Microwave/Imager (SSM/I) for the shortwave and long-wave radiative fluxes, and for estimates of SST. For turbulent flux calculations, we use the bulk aerodynamic method with satellite estimates for wind speed and atmospheric humidity and temperature.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.1
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• pp.87-95
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• 2016

Recently, the interests of the precise localization are rapidly increasing, which are linked to IoT(Internet of Things) sensors. The precise localization in indoor environment can be utilized in navigation, security, anti-collision, and various location based services etc. However, conventional positioning sensors, such as PIR, ultrasonic, microwave etc. are vulnerable to weather or insensitive to direction of subject movement or low precision performance. In this paper we implement a UWB-IR localization system for long distance and high-precision localization, which is not affected by temperature, light and weather. The proposed system was divided and designed by H/W, Antenna, S/W parts, each of which was designed based on an accurate analysis and simulation. As a result, we can implemented and verified UWB IR system with precise localization performance.

• Korean Journal of Remote Sensing
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• v.3 no.2
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• pp.89-102
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• 1987

Microwave remote sensing plays a major role in areas where cloud cover and darkness prevail. In this and the next paper, models are described for the radar backscatter from two major types of sea ice in an attempt to specify optimum sensor parameters and to allow the most reliable image interpretation possible. Here, the physical-optics model using an exponential correlation function is shown to be able to presict the signatures of first-year ice under cold conditions. The effect of volume scattering by small inclusions in the first-year ics is shown to be negligible using a semi-empirical volume scattering model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.2
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• pp.1555-1562
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• 2015

Metal oxide semiconductors have been applied in several areas, such as solar cells, sensor, optical elements and displays, due to the high surface area, unique electrical and optical characteristics. Zinc oxide among the metal oxide has excellent physicochemical properties. Zinc oxide is a n-type semiconductor with a wide direct transition band gap of 3.37 eV at room temperature and large exciton binding energy of 60 meV. Cation-doped zinc oxide studies were conducted to complement the electrical and optical characteristics. In this paper, Al-doped ZnO was synthesized by hydrothermal synthesis using microwaves. ZnO was synthesized by adjusting the precursor ratio and using different dopants. The optimal ZnO synthesis conditions for crystal shape and optical properties were determined. The optical properties of aluminum doped zinc oxide were then examined by SEM, XRD, PL, UV-vis absorbance spectrum, and EDS.

• Korean Journal of Remote Sensing
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• v.15 no.1
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• pp.21-30
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• 1999

The CLW (Cloud Liquid Water) is a parameter of vital interest in both modeling and forecasting weather. In mesoscale models, the magnitude of latent heat effects corresponds to the amount of CLW, which is important in the development of a certain weather system. The goal of this study is the estimation of CLW by GMS-5 data which is compared with that of SSM/I data and GMR(Grounded Microwave Radiometer)data. First of all, we found out the relationship of cloud albedo to cloud thickness, and caculated the CLW using the result of the relationship. The CLW amount of SSM/I or GMR and that of GMS-5 were compared, respectively. The correlation coefficient was about 0.86 and RMSE was 9.23 mg/$cm^2$ between GMS-5 data and GMR data. And also the correlation coefficient was 0.84 and RMSE was 14.02 mg/$cm^2$ between GMS-5 data and SSM/I data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.1
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• pp.39-46
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• 2015

In this paper, a gas sensor using a modified $90^{\circ}$ hybrid coupler structure with conducting polymer which operates at 2.4 GHz is represented. Conducting polymers are used to the gas sensing material in proposed sensors. The conducting polymer varies its electrical property, such as work function and conductivity corresponding to the certain gas. To verify this variation of electrical property of conducting polymer at microwave frequencies, the conducting polymer is incorporated with the $90^{\circ}$ hybrid coupler structure, and this proposed sensor operates as reflection type variable attenuator and variable phase shifter. The conducting polymer is employed as impedence-variable transmission lines that cause a impedance mismatching between the general transmission line and conducting polymer. The experiment was conducted with 100 ppm ethanol gas at temperature of $28^{\circ}C$ and relative humidity of 85 %. As a result, the amplitude deviation of $S_{21}$ is 0.13 dB and the frequency satisfying ${\angle}S_{21}=360^{\circ}$ is shifted about 2.875 MHz.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.306-309
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• 2007

Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations (J-OFURO) includes global ocean surface heat flux data derived from satellite data and are used in many studies related to air-sea interaction. Recently latent heat flux data version 2 was constructed in J-OFURO. In version 2 many points are improved compared with version 1. A bulk algorithm used for estimation of latent heat flux is changed from Kondo (1975) to COASRE 3.0(Fairall et al., 2005). In version 1 we used NCEP reanalysis data (Reynolds and Smith, 1994) as SST data. However, the temporal resolution of the data is weekly and considerably low. Recently there are many kinds of global SST data because we can obtain SST data using a microwave radiometer sensor such as TRMM/MI and Aqua/AMSR-E. Therefore, we compared many SST products and determined to use Merged satellite and in situ data Global Daily (MGD) SST provided by Japan Meteorological Agency. Since we use wind speed and specific humidity data derived from one DMSP/SSMI sensor in J-OFURO, we obtain two data at most one day. Therefore, there may be large sampling errors for the daily-mean value. In order to escape this problem, multi-satellite data are used in version 2. As a result we could improve temporal resolution from 3-days mean value in version 1 to daily-mean value in version 2. Also we used an Optimum Interpolation method to estimate wind speed and specific humidity data instead of a simple mean method. Finally the data period is extended to 1989-2004. In this presentation we will introduce latent heat flux data version 2 in J-OFURO and comparison results with other surface latent heat flux data such as GSSTF2 and HOAPS etc. Moreover, we will present validation results by using buoy data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1912-1921
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• 2015

In this paper, we introduce a testbed for testing the RF energy transfer technology in the Internet of Things (IoT) environment, and provide experimental results obtained by using the testbed. The IoT environment considered in this paper consists of a power beacon, which is able to wirelessly transfers energy via microwave, and multiple sensor nodes, which makes use of the energy received from the power beacon. We have implemented the testbed to experiment the RF energy transfer in such IoT environment. We have used off-the-shelf hardware components to build the testbed and have made the tesbed controlled by software so that various energy and data transmission protocol experiments can easily be conducted. We also provide experimental results and discuss the future research direction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.11
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• pp.1653-1660
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• 2016

The synthetic aperture rardar (SAR) is an active sensor using microwaves. It transmits a microwave signal, called a chirp pulse, and receives the reflected signal in a moving platform such as satellite and unmanned aerial vehicle. Since this sensor uses microwaves that can penetrate the atmosphere, SAR generates the images regardless of light and weather conditions. However SAR operates on the moving platform, the Doppler shift and the side-looking observation method should be considered. In addtion, a residual image or ghost image can be occurred according to selection of the pulse repetition frequency (PRF). In this paper, a range design of the PRF for the L-band spaceborne SAR system is studied for prevention of SAR image distortion. And the system is studied for prevention of SAR image distortion. And the system parameter and the PRF are calibrated iteratively according to the proposed system design procedure and design constraints. The MATLAB based on SAR system simulator has been developed to verify the validity of calculated PRF. The developed simulator assumes that SAR sensor is operated by the PRF calculated from the design. The results of the simulator show that the targets in image has a valid peak to side-lobe ratio (PSLR) so that the PRF can be used for the spaceborne SAR sensor.