• Journal of the Korean Association of Geographic Information Studies
• /
• v.3 no.2
• /
• pp.87-97
• /
• 2000

Recently microwave remote sensing technology is widely used in Global environment study. Expecially Synthetic Aperture Radar sensing technique has many application to geographic information. Proposed AIRSAR Pacific Rim Deployment 2000(PACRIM2) is a NASA-sponsored science mission. AIRSAR is a test-bed instrument for new radar technologies in near future from space shuttle and satellite systems. In this paper the overview of PACRIM2 overview and sensors are introduced. Examples of processed data from new sensors are also shown.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.2
• /
• pp.119-125
• /
• 2017

We retrieved rotational temperatures from emission lines of the OH airglow (8-3) band in the sky spectra of the Sloan digital sky survey (SDSS) for the period 2000-2014, as part of the astronomical observation project conducted at the Apache Point observatory ($32^{\circ}N$, $105^{\circ}W$). The SDSS temperatures show a typical seasonal variation of mesospheric temperature: low in summer and high in winter. We find that the temperatures respond to solar activity by as much as $1.2K{\pm}0.8K$ per 100 solar flux units, which is consistent with other studies in mid-latitude regions. After the seasonal variation and solar response were subtracted, the SDSS temperature is fairly constant over the 15 year period, unlike cooling trends suggested by some studies. This temperature analysis using SDSS spectra is a unique contribution to the global monitoring of climate change because the SDSS project was established for astronomical purposes and is independent from climate studies. The SDSS temperatures are also compared with mesospheric temperatures measured by the microwave limb sounder (MLS) instrument on board the Aura satellite and the differences are discussed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.259-263
• /
• 2008

최근 기후변화로 인해 집중호우, 태풍, 폭설 등 악기상 발생이 빈번해지고 있으며, 특히 태풍은 단일 기상현상 가운데 가장 강력하며, 태풍으로 인하여 집중호우 폭풍 및 해일 등 부차적 악기상이 함께 발생하여 인명 및 경제 사회적인 피해 또한 막대하지만, 태풍으로 인한 강수량 측정은 다른 현상에 비해 정확한 측정이 어렵다. 이것은 태풍이 발생에서 소멸까지 일생의 대부분을 해상에서 보내, 육상 관측으로는 정확한 강수량 측정이 어렵기 때문이다. 그러나 위성자료를 활용하면 해상에서의 태풍 구름에 의한 강수분포를 추정할 수 있으며, 특히 구름을 투과하여 아래 내부구조 파악이 가능한 마이크로파 영역의 적외복사에너지를 이용하면 좀더 정확한 강수량 자료를 얻을 수 있을 것이다. 그러나 관측영역 확대를 위해서는 가능한 마이크로파위성자료를 합성처리하여 활용하는 것이 효과를 얻을 수 있을 것이다. 본 연구에서는 현재 기상청에서 수신하고 있는 Aqua/AMSR-E, SSM/I, TMI, QuilSCAT 등에서 산출되는 강수량을 상호 검증기법을 이용하여 합성처리 하였다. 위성자료마다 정확도와 해상도가 다른 것에 대해서는 높은 정확도에 가중치를 주고, 고해상도 자료에 맞추어 픽셀 크기를 맞추었다. 사용한 자료는 2005년$\sim$2007년 간 발생한 태풍 중에서 우리나라에 영향을 준 나비, 나리, 에위니아 등 3개 사례이며, 검증은 자동관측자료(AWS : Automatic Weather Station)자료와 일본 AWS자료(AMEDAS : Automatic Measurement Data Aquisition System) 및 미해군 연구소 발표자료를 이용하여, 시계열오차 분석 및 산포도를 분석하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.11 no.3
• /
• pp.153-163
• /
• 1986

GaAs, one of the III-V compounding semicondnctors, has been widely employed as base materials for the fabrication of the ultra-high-speed devices in the filelds of DBS, optical communications, MMIC'S and digital IC'S. There have been some reports on 4Kx4bit SRAM by D/E MESFET'S, 4K bit SRAM by HEMT'S, and receiver front ends for X-band by MMIC technologies, respectively. This paper reviews GaAs materials, wafer fabrication processes, device applications, and design aspects, and, finally, descusses the future of the ultra-high-spped-devices.

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.278-281
• /
• 2007

The purpose of this study is to develop snow and sea ice detection algorithm in Communication, Ocean and Meteorological Satellite (COMS) meteorological data processing system. Since COMS has only five channels, it is not affordable to use microwave or shortwave infrared data which are effective and generally used for snow detection. In order to estimate snow and sea ice coverage, combinations between available channel data(mostly visible and 3.7 ${\mu}m$) are applied to the algorithm based on threshold method. As a result, the COMS snow and sea ice detection algorithm shows reliable performance compared to MODIS products with channel limitation. Specifically, there is partial underestimation over the complicated vegetation area and overestimation over the area of high level clouds such as cirrus. Some corrections are performed by using water vapor and infrared channels to remove cloud contamination and by applying NDVI to detect more snow pixels for the underestimated area.

• Proceedings of the KSRS Conference
• /
• 1998.09a
• /
• pp.37-42
• /
• 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.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2005.08a
• /
• pp.75-87
• /
• 2005

Remote sensing(RS)- and geographic information system(GIS)-based information management to measure and assess agri-environment schemes, and to quantify and map environment indicators for nature and land use, climate change, air, water and energy balance, waste and material flow is in high demand because it is very helpful in assisting decision making activities of farmers, government, researchers, and consumers. The versatility and ability of RS and GIS containing huge soil database to assess agricultural environment spatially and temporally at various spatial scales were investigated. Spectral and microwave observations were carried out to characterize crop variables and soil properties. Multiple sources RS data from ground sensors, airborne sensors, and also satellite sensors were collected and analyzed to extract features and land cover/use for soils, crops, and vegetation for support precision agriculture, soil/land suitability, soil property estimation, crop growth estimation, runoff potential estimation, irrigated and the estimation of flooded areas in paddy rice fields. RS and GIS play essential roles in a management and monitoring information system. Biosphere-atmosphere interection should also be further studied to improve synergistic modeling for environment and sustainability in agri-environment schemes.

• Atmosphere
• /
• v.28 no.2
• /
• pp.141-151
• /
• 2018

The KIAPS global model and data assimilation system were extended to assimilate brightness temperature from the Sondeur $Atmosph{\acute{e}}rique$ du Profil $d^{\prime}Humidit{\acute{e}}$ Intertropicale par $Radiom{\acute{e}}trie$ (SAPHIR) passive microwave water vapor sounder on board the Megha-Tropiques satellite. Quality control procedures were developed to assess the SAPHIR data quality for assimilating clear-sky observations over the ocean, and to characterize observation biases and errors. In the global cycle, additional assimilation of SAPHIR observation shows globally significant benefits for 1.5% reduction of the humidity root-mean-square difference (RMSD) against European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) analysis. The positive forecast impacts for the humidity and temperature in the experiment assimilating SAPHIR were predominant at later lead times between 96- and 168-hour. Even though its spatial coverage is confined to lower latitudes of $30^{\circ}S-30^{\circ}N$ and the observable variable is humidity, the assimilation of SAPHIR has a positive impact on the other variables over the mid-latitude domain. Verification showed a 3% reduction of the humidity RMSD with assimilating SAPHIR, and moreover temperature, zonal wind and surface pressure RMSDs were reduced up to 3%, 5% and 7% near the tropical and mid-latitude regions, respectively.

• Journal of the Korean Magnetic Resonance Society
• /
• v.6 no.2
• /
• pp.84-88
• /
• 2002

Dating and dosimetry using electron spin resonance (ESR) in 20th Century developed at both Yamaguchi University and Osaka University have been reviewed with emphasis on new prospects and strategies in 21th century. Natural radiation have been generating radicals that accumulated in archaeological and geological materials. ESR detects these radicals and the ESR signal intensity is proportional to the radiation dose and therefore the age. The assessment of the total dose of natural radiation and the annual dose rate give their ESR ages. The ESR dating of stalactites and stalagmites ant Akiyoshi cave in Yamaguchi prefecture in 1975 was extended to anthropological dating using bones and tooth enamel excavated in Greek Petralona cave. Fossils of shells and corals gave the ages of marine terraces and sea-level changes. Quartz grains gave the ages of geothermal alteration and fault movements. Future ESR dating of ices at outer planets anf their satellite are also investigated as basic studies for ices od $H_2O,\;CO_2,\;SO_2$ as well as terrestrial hydrates in laboratory. Atomic bomb radiation dosimetry at Hiroshima and Nagasaki using ESR lead to the dosimetry of personnel, Chemobyl and JCO criticality accidents. Monitoring of radiation dose with sensitive materials with tissue equivalence are being developed. finally a new scanning ESR imaging apparatus (a near field microwave microscope) developed in our laboratory gave ESR images of Radicals from fossils to Si-CVD and diamond films as summarized in my book in 2002.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.187-187
• /
• 2015

인공위성을 이용한 토양수분의 측정은, 범지구적인 물순환 분석에 있어서, 수문학적인 인자들의 시공간적인 변화를 예측, 분석하는데 있어 가장 효율적인 방법으로 제안되어왔다. 현재 국/내 외 적으로 사용하는 토양수분 위성은 Soil Moisture and Ocean Salinity (SMOS), Advanced SCATerometer (ASCAT)이 많이 사용되고 있으며, 더불어 일본에서 최근에 발사 된 Advanced Microwave Scanning Radiomter 2 (AMSR2) 센서를 통한 토양수분도 데이터도 적극 활용 되고 있다. 각 위성은 토양수분을 산출 하는 알고리즘, 파장대 그리고 위성 통과 시간 등이 각기 다르므로, 이러한 위성의 데이터를 사용하기 위해서는 지점 데이터와의 검증이 필수적으로 필요하게 된다. 이에따라 본 연구에서는 위성 데이터와 Global Land Data Assimilation System (GLDAS)와의 비교를 통해 각 위성데이터의 동아시아 지역에서의 효용성을 평가하였다. 동아시아의 건조한 지역에서는 SMOS가 가장 좋은 토양수분 데이터 결과를 보여주었으며, 다른 많은 지역에서는 ASCAT이 우세한 결과를 보여주었다. 하지만 한반도 지역의 특정 지역에서는 AMSR2의 토양수분 값이 ASCAT을 뛰어넘는 좋은 결과를 보여주는 결과가 도출되었다. 추가적으로, SMOS의 경우 Radio Frequency Interference (RFI)의 영향으로 한반도지역 토양수분을 측정하는 것에는 많은 무리가 있음을 알 수 있었다.