• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.855-862
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• 2017

Due to the weight reduction and miniaturization of satellites, there is a growing interest in low-cost launch vehicles, which are cheaper to launch than larger launch vehicles. One of the most cost-effective ways to reduce the cost of launch vehicles is the reuse of vehicles. Most companies that are developing low cost launch vehicles are also adopting a vehicles reuse approach. Along with this reuse purpose, the demand for environmentally friendly space launch vehicles has increased, so the choice of fuel used for low cost launch vehicles has also become very important. Methane and hydrogen-enriched compressed natural gas (HCNG), which makes more energy-efficient by adding hydrogen to methane, are considered to be the most suitable when considering other factors such as energy density among the fuels that are eco-friendly and capable of reusing the launch vehicles. This study investigated the trends of low-cost launch vehicle and rocket fuel in the world as a reference for setting up domestic space development after the development of Korea Space Launch Vehicle-II.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.3
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• pp.214-224
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• 2018

Continuous space development increases the occurrence probability of space hazards such as collapse of a satellite and collision between a satellite and space debris. In Korea, a space surveillance network with optical system has been developed; however, the radar technology for an independent space surveillance needs to be secured. Herein, an L-band phased array radar system for the detection and tracking of space objects is proposed to provide a number of services including collision avoidance and the prediction of re-entry events. With the mission analysis of space surveillance and the case analysis of foreign advanced radar systems, the radar parameters are defined and designed. The proposed radar system is able to detect a debris having a diameter of 10 cm at a maximum distance of 1,576 km. In addition, we confirmed the possibility of using the space surveillance mission for domestic satellites through the analysis of the detection area.

• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.415-422
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• 2013

The contents development for the Internet and cyber tour has been attempted in a number of areas. 3D topography of the spatial environment, land planning and land information contents as a 3D tour of the future ubiquitous city safe for tourism due to the implementation of information made available major area. Domestic service, and in urban areas of the country where land and precise spatial information in order to shoot satellites and aircraft in the area you want to mount the camera on a variety of photo images taken by conducting 3D spatial that is required is able to obtain the information. Geo spatial information in a variety of direct or indirect acquisition of the initial spatial data into a database for accurate collection, storage, editing, manipulation and application technology changes in the future by establishing a database of 3D spatial by securing content organization ubiquitous tourist to take advantage of new tourism industry was greatly. As a result of this study for future tourism using geo spatial information and analysis of 3D modeling by intelligent land information indirectly, with quite a few stereo site experience and a variety of tourist spatial acquisition and utilization of information could prove.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.1
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• pp.23-29
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• 2014

The emergence of high resolution satellite images and the evolution of spatial resolution facilitate various studies using high resolution satellite images. Above all, target detection algorithms are effective for monitoring of traffic flow and military surveillance and reconnaissance because vehicles, airplanes, and ships on broad area could be detected easily using high resolution satellite images. Recently, many satellites are launched from global countries and the diversity of satellite images are also increased. On the contrary, studies on comparison about the spatial resolution or target detection, especially, are insufficient in domestic and foreign countries. Therefore, in this study, effects of spatial resolution on target detection are analyzed using the PSO target detection algorithm. The resampling techniques such as nearest neighbor, bilinear, and cubic convolution are adopted to resize the original image into 0.5m, 1m, 2m, 4m spatial resolutions. Then, accuracy of target detection is assessed according to not only spatial resolution but also resampling method. As a result of the study, the resolution of 0.5m and nearest neighbor among the resampling methods have the best accuracy. Additionally, it is necessary to satisfy the criteria of 2m and 4m resolution for the detection of airplane and ship, respectively. The detection of airplane need more high spatial resolution than ship because of their complexity of shape. This research suggests the appropriate spatial resolution for the plane and ship target detection and contributes to the criteria of satellite sensor design.

• Korean Journal of Remote Sensing
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• v.35 no.6_2
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• pp.1031-1035
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• 2019

Nowadays, the utilization infrastructure of domestic satellite information is expanding rapidly. Especially, the development of agriculture and forestry satellite is expected to drastically change the utilization of satellite information in the forest sector. The launch of the satellite is expected in 2023. Therefore, NIFoS and academic experts in forest sectors have prepared "Special Issue on Forest Management Research using Optical Sensors and Remote Sensing Technologies" in order to understand new remote sensing technologies and suggest the future direction of forest research and decision-making. This special issue is focused on a variety of fields in forest remote sensing research, including forest resources survey, forest disaster detection, and forest ecosystem monitoring. The new research topics for remote sensing technologies in forest sector focuses on three points: development of new indicators and information for accurate detection of forest conditions and changes, the use of new information sources such as UAV and new satellites, and techniques for improving accuracy through the use of artificial intelligence techniques.

• Korean Journal of Remote Sensing
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• v.35 no.5_2
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• pp.763-772
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• 2019

High-resolution satellites capable of observing the Earth periodically enhance applicability of remote sensing in the field of national disaster management from national disaster pre-monitoring to rapid recovery planning. The National Disaster Management Research Institute (NDMI) has been developed various satellite-based disaster management technologies and applied to disaster site operations related to typhoons and storms, droughts, heavy snowfall, ground displacement, heat wave, and heavy rainfall. Although the limitation of timely imaging of satellite is a challenging issue in emergent disaster situation, it can be solved through international cooperation to cope with global disasters led by domestic and international space development agencies and disaster organizations. This article of special issue deals with the scientific disaster management technologies using remote sensing and advanced equipments of NDMI in order to detect and monitor national disasters occurred by global abnormal climate change around the Korean Peninsula: satellite-based disaster monitoring technologies which can detect and monitor disaster in early stage and advanced investigation equipments which can collect high-quality geo-information data at disaster site.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1517-1526
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• 2021

With the recent global and domestic development of Earth observation satellites, the applications of satellite images have been widened. Research for improving the geometric accuracy of satellite images is being actively carried out. This paper studies the possibility of automated ground control point (GCP) generation for CAS-4 satellite, to be launched in 2025 with the capability of image acquisition at 5 m ground sampling distance (GSD). In particular, this paper focuses to check whether GCP chips with 25 cm GSD established for CAS-1 satellite images can be used for CAS-4 and to check whether optimalspatial resolution for matching between CAS-4 images and GCP chips can be determined to improve matching performance. Experiments were carried out using RapidEye images, which have similar GSD to CAS-4. Original satellite images were upsampled to make satellite images with smaller GSDs. At each GSD level, up-sampled satellite images were matched against GCP chips and precision sensor models were estimated. Results shows that the accuracy of sensor models were improved with images atsmaller GSD compared to the sensor model accuracy established with original images. At 1.25~1.67 m GSD, the accuracy of about 2.4 m was achieved. This finding lead that the possibility of automated GCP extraction and precision ortho-image generation for CAS-4 with improved accuracy.

• Journal of Navigation and Port Research
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• v.43 no.1
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• pp.42-48
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• 2019

The significance of PNT information in the fourth industrial revolution is viewed differently in relation to the past. Autonomous vehicles, autonomous vessels, smart grids, and national infrastructure require sustainable and reliable services in addition to their high precision service. Satellite navigation system, which is the most representative system for providing PNT information, receive signals from satellites outside the earth so signal reception power is low and signal structures for civilian use are open to the public. Therefore, it is vulnerable to intentional and unintentional interference or hacking. Satellite navigation systems, which can easily acquire high performance of PNT information at low cost, require alternatives due to its vulnerability to the hacking. This paper proposed R-Mode (Ranging Mode) technology that utilizes currently operated navigation and communication infrastructure in terms of Signals of OPportunity (SoOP). For this, the Nationwide Differential Global Navigation Satellite System (NDGNSS), which currently gives a service of Medium Frequency (MF) navigation signal broadcasting, was used to validate the feasibility of a backup infrastructure in domestic maritime areas through simulation analysis.

• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.571-585
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• 2022

As the threat of natural disasters such as droughts, floods, forest fires, and landslides increases due to climate change, social demand for high-resolution soil moisture retrieval, such as Synthetic Aperture Radar (SAR), is also increasing. However, the domestic environment has a high proportion of mountainous topography, making it challenging to retrieve soil moisture from SAR data. This study evaluated the usability of Sentinel-1 SAR, which is applied with the Artificial Neural Network (ANN) technique, to retrieve soil moisture. It was confirmed that the backscattering coefficient obtained from Sentinel-1 significantly correlated with soil moisture behavior, and the possibility of stand-alone use to correct vegetation effects without using auxiliary data observed from other satellites or observatories. However, there was a large difference in the characteristics of each site and topographic group. In particular, when the model learned on the mountain and at flat land cross-applied, the soil moisture could not be properly simulated. In addition, when the number of learning points was increased to solve this problem, the soil moisture retrieval model was smoothed. As a result, the overall correlation coefficient of all sites improved, but errors at individual sites gradually increased. Therefore, systematic research must be conducted in order to widely apply high-resolution SAR soil moisture data. It is expected that it can be effectively used in various fields if the scope of learning sites and application targets are specifically limited.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.224-235
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• 2022

This study aimed to confirm the status of media reports on space hazards using topic modeling analysis of media articles that are related to space hazards for the past 12 years. Therefore, Latent Dirichlet Allocation (LDA) analysis was performed by collecting over 1200 space hazards articles between 2010 and 2021 on solar storm, artificial space objects, and natural space objects from BIGKins news platform. The articles related to solar storm focused on three topics: the effect of solar explosion on satellites; effect of solar explosion on radio communication in Korea, centered on the Korean Space Weather Center; and relationship between aircrew and space radiation. The articles related to artificial space objects focused on three topics: the threat of space garbage to satellite and space stations and the transition of useful objects into space junk; the relationship between space garbage and humanity as shown in movies; and the effort of developed countries for tracking, monitoring, and disposing of space garbage. The articles related to natural space objects focused on two topics: International Space Agency's tracking and monitoring of near-Earth asteroids and the countermeasures of collisions, and the evolution and extinction of dinosaurs and mammals, with a focus on the collisions of asteroids or comets. Therefore, this study confirmed that domestic media play a role in conveying dangers of space hazards and arousing the attention of public using a total of eight themes in various fields such as society and culture, and derived education method and policy on space hazards.