• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.116-121
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• 2012

For the purpose of drawing out the technological criteria for the development of an Low Earth Orbit Meteorological Satellite some characteristics of infrared and microwave sensors on the payload were analysed by approaching theoretically. In addition, the channel requirements and interface requirements of the microwave sensors equipped on the payloads of the existing foreign Low Earth Orbit Meteorological Satellites were analysed with respect to the development of an Earth Orbit Meteorological Satellite payload. In this paper, the multipurpose satellite bus and the CAS 500 platform as the interface requirements of an Low Earth Orbit Meteorological Satellite, and core subsystem and principle functional requirements of a satellite control system were systematically described.

• Korean Journal of Remote Sensing
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• v.37 no.5_1
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• pp.1215-1227
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• 2021

Surface reflectance, as a product of the absolute atmospheric correction process of low-orbit satellite imagery, is the basic data required for accurate vegetation analysis. The Commission on Earth Observation Satellite (CEOS) has conducted research and guidance to produce analysis-ready data (ARD) on surface reflectance products for immediate use by users. However, this trend is still in the early stages of research dealing with ARD for high-resolution multispectral images such as KOMPSAT-3A and CAS-500, as it targets medium- to low-resolution satellite images. This study first summarizes the types of distribution of ARD data according to existing cases. The link between Open Data Cube (ODC), the cloud-based satellite image application platforms, and ARD data was also explained. As a result, we present practical ARD deployment steps for high-resolution satellite images and several types of application models in the conceptual level for high-resolution satellite images deployed in ODC and cloud environments. In addition, data pricing policies, accuracy quality issue, platform applicability, cloud environment issues, and international cooperation regarding the proposed implementation and application model were discussed. International organizations related to Earth observation satellites, such as Group on Earth Observations (GEO) and Committee on Earth Observation Satellites (CEOS), are continuing to develop system technologies and standards for the spread of ARD and ODC, and these achievements are expanding to the private sector. Therefore, a satellite-holder country looking for worldwide markets for satellite images must develop a strategy to respond to this international trend.

• Journal of Space Technology and Applications
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• v.3 no.3
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• pp.229-238
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• 2023

One of the important ways to improve the performance of magnetometers in satellite exploration is to reduce magnetic noise from satellites. One of the methods to decrease magnetic noise is by extending the satellite boom. However, this approach is often not preferred due to its high cost and operational considerations. Therefore, in many cases, removing interference from the satellite platform in the measured dataset is widely utilized after data acquisition. In this study, we would like to introduce an algorithm for removing magnetic noise observed from magnetometers installed on two solar panels and one main body without a boom.

• Korean Journal of Remote Sensing
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• v.36 no.5_2
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• pp.989-1006
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• 2020

Building change monitoring based on building detection is one of the most important fields in terms of monitoring artificial structures using high-resolution multi-temporal images such as CAS500-1 and 2, which are scheduled to be launched. However, not only the various shapes and sizes of buildings located on the surface of the Earth, but also the shadows or trees around them make it difficult to detect the buildings accurately. Also, a large number of misdetection are caused by relief displacement according to the azimuth and elevation angles of the platform. In this study, object-based building detection was performed using the azimuth angle of the Sun and the corresponding main direction of shadows to improve the results of building change detection. After that, the platform's azimuth and elevation angles were used to detect changed buildings. The object-based segmentation was performed on a high-resolution imagery, and then shadow objects were classified through the shadow intensity, and feature information such as rectangular fit, Gray-Level Co-occurrence Matrix (GLCM) homogeneity and area of each object were calculated for building candidate detection. Then, the final buildings were detected using the direction and distance relationship between the center of building candidate object and its shadow according to the azimuth angle of the Sun. A total of three methods were proposed for the building change detection between building objects detected in each image: simple overlay between objects, comparison of the object sizes according to the elevation angle of the platform, and consideration of direction between objects according to the azimuth angle of the platform. In this study, residential area was selected as study area using high-resolution imagery acquired from KOMPSAT-3 and Unmanned Aerial Vehicle (UAV). Experimental results have shown that F1-scores of building detection results detected using feature information were 0.488 and 0.696 respectively in KOMPSAT-3 image and UAV image, whereas F1-scores of building detection results considering shadows were 0.876 and 0.867, respectively, indicating that the accuracy of building detection method considering shadows is higher. Also among the three proposed building change detection methods, the F1-score of the consideration of direction between objects according to the azimuth angles was the highest at 0.891.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.126-127
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• 2003

원예산물의 밀도나 비중은 내부성분, 숙도, 내부붕괴(internal breakdown)와 같은 생리장해에 큰 영향을 받기 때문에, 밀도를 측정함으로써 내부품질에 대한 간접적인 판정이 가능하다고 보고되고 있다. 이 연구는 수박의 밀도와 당도와의 상관관계를 구명하고자 수행하였으며, 이를 위해 밀도의 실시간 계측시스템을 개발하였다. 현재 농산물의 밀도를 어느 정도 측정 정밀도를 유지하면서도 신속하게 측정할 수 있는 방법은 부력법(platform scale method)이다. 이 방법은 일정 크기의 용기에 물을 가득 채운 후 대상물을 담가 배제된 물의 무게를 측정하여 밀도를 환산한다. 그러나 매번 측정할 때마다 물을 보충하고, 물을 계량해야하는 등 전처리과정이 복잡하고, 1회 측정하는데 3~5분 정도가 소요되는 단점이 있고, 또한 인력 측정시 반복간 오차가 클 것으로 예상된다. 따라서 이 연구에서는 이 같은 계측상의 번거로움을 해소하고 동시에 신속하고 반복간 측정정밀도를 높일 수 있도록 수박 밀도 실시간 계측시스템을 설계 제작하였다. 시스템은 투명아크릴 수조($\Phi$400$\times$500), 로드셀, 프레임, 채반, 전기모터, 제어장치 및 컴퓨터로 구성하였다. 밀도 계측은 인장형 로드셀(CAS SB-20L, Max. 20kg)을 사용하여 대기중에서와 수박을 완전히 물에 잠기도록 한 후 무게를 각각 측정하여 밀도를 환산하였다. 밀도 계측시스템에 이용한 AD변환기의 분해능은 12bit이고, 수박의 무게 측정범위를 4~10kg로 가정할 때 20kg 로드셀의 1 digit(1bit)로 발생되는 오차는 0.09~0.24%FS 이었고, 따라서 이 시스템의 밀도 해상도는 0.001g/㎤이하였다. 시스템 평가를 위해 탄력이 좋은 고무풍선에 수박 크기 정도로 물을 채워 고정채반에 넣고 밀도를 측정한 결과 1.002g/㎤을 나타냈다. 즉 물의 이론밀도인 1g/㎤에 근접한 값을 보여 정확한 밀도 계측이 가능한 것으로 판단되었다. 또한 밀도 계측시스템의 측정 반복간 정밀도를 파악하기 위해 수박 6개를 임으로 선정하여 3반복 측정 시험한 결과, 측정표준편차가 0.001~0.004g/㎤로 해상도보다는 다소 높았으나 대체로 양호한 결과를 나타냈다. 수박 35개를 이용하여 개발 계측시스템과 사람이 직접 부력법으로 밀도를 측정 비교한 결과, 계측시스템에 의해 측정된 수박 밀도가 사람이 측정했을 때 보다 낮게 측정되었다. 수박의 외관인자(무게, 길이, 직경, 체적), 밀도와 당도의 상관관계 구명시험을 위해 원예연구소 시험포장에서 재배된 삼복꿀수박 총 74개를 공시재료로 하였고, 시험은 출수일별로 10~14개씩 수확하여 외관인자, 밀도, 당도를 각각 측정하고, 이들 인자들간의 상관관계를 구명하였다. 외관인자들간에는 높은 상관관계를 보였으나, 외관인자들과 밀도, 외관인자들과 당도, 밀도와 당도와는 매우 낮은 상관관계를 나타냈다.