• Korean Journal of Remote Sensing
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• v.32 no.3
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• pp.287-305
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• 2016

Over the past half century, satellites have continuously expanded their roles in remote sensing applications. As the number of satellites to be launched are expected to continuously increase in coming years, the research on satellite payloads will be in high demands. Earth Observation (EO) satellites are nowadays widely utilized for various purposes. Especially, Agriculture and forestry applications are considered as their major application areas. Since about 85% of domestic land cover is classified as forest or cropland areas, it would be reasonable to suggest that the demand for these satellites should be of high priority. In this paper, a comprehensive analysis is performed on the technical specifications of satellite payloads that may be applicable to agricultural applications. We attempted to build a solid database on payload specifications by collecting relevant information available from various related institutes and academic research works. A number of experts involved in national agricultural research and satellite development programs have been invited to investigate required payload design. Based on the current technology development status and future plan, multiple options for future satellite payload designs have been suggested bearing in mind that the results may be applicable to the future agriculture and forestry satellite payload design. The proposed payload specifications are analyzed in depth through satellite operation simulations under the mission of observing the national agriculture areas. The proposed design scheme and simulation results may be used as technical references to satellite payload design for future space missions.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.41-47
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• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.273-284
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• 2011

A method of stellar source selection for validating the quality of image is investigated for a low Earth orbit optical remote sensing satellite. Image performance of the optical payload needs to be validated after its launch into orbit. The stellar sources are ideal source points that can be used to validate the quality of optical images. For the image validation, stellar sources should be the brightest as possible in the charge-coupled device dynamic range. The time delayed and integration technique, which is used to observe the ground, is also performed to observe the selected stars. The relations between the incident radiance at aperture and V magnitude of a star are established using Gunn & Stryker's star catalogue of spectrum. Applying this result, an appropriate image performance index is determined, and suitable stars and areas of the sky scene are selected for the optical payload on a remote sensing satellite to observe. The result of this research can be utilized to validate the quality of optical payload of a satellite in orbit.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3884-3910
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• 2016

Intrusion Detection System (IDS) in general considers a big amount of data that are highly redundant and irrelevant. This trait causes slow instruction, assessment procedures, high resource consumption and poor detection rate. Due to their expensive computational requirements during both training and detection, IDSs are mostly ineffective for real-time anomaly detection. This paper proposes a dimensionality reduction technique that is able to enhance the performance of IDSs up to constant time O(1) based on the Principle Component Analysis (PCA). Furthermore, the present study offers a feature selection approach for identifying major components in real time. The PCA algorithm transforms high-dimensional feature vectors into a low-dimensional feature space, which is used to determine the optimum volume of factors. The proposed approach was assessed using HTTP packet payload of ISCX 2012 IDS and DARPA 1999 dataset. The experimental outcome demonstrated that our proposed anomaly detection achieved promising results with 97% detection rate with 1.2% false positive rate for ISCX 2012 dataset and 100% detection rate with 0.06% false positive rate for DARPA 1999 dataset. Our proposed anomaly detection also achieved comparable performance in terms of computational complexity when compared to three state-of-the-art anomaly detection systems.

• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.31-36
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• 2010

A small unmanned helicopter was suggested to replace the conventional spray system. Aerial application using an agricultural helicopter helps precise and timely spraying, and reduces labor intensity and environmental pollution. In this research, a rotor system (SW05) was developed and its lift capability was evaluated. Lift force for the dead weight of the helicopter was obtained at the grip pitch angle of $12^{\circ}$. As the pitch angle increased to $14^{\circ}$ and $16^{\circ}$, the payload increased to 176 N and 216 N, respectively. Compared with SW04 airfoil performance in the total lift, the SW05 airfoil showed nearly the same capacity, but the payload of the SW05 was reduced because of the increased dead weight. A rated flight condition was defined as lifting mean payload of 294 N with the grip pitch angles of $16{\sim}17^{\circ}$ at the rotor rotating speed of 850~950 rpm for the adjusted engine power. The fuel consumption would be 4.8~6.0 L/hr, and the air temperature of cooling fan should be kept below $160^{\circ}C$.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.229-231
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• 1994

For the effective use of satellite communication transponder, tests for the payload system such as IOT(In-Orbit Test), RPM(Routine Payload Monitoring), CSM(Communicatios System Monitoring), and REV(Remote Earth-Station Verification) have to be conducted. Those tests are used in order to verify the condition and generic design of the satellite, to provide a database for operational calculations, and to maintain the quality of communication services. As the satellite communication system gets with wider expansion with higher complexity of operation, tests for the communication system also need more complex operation that usesophisticated computer-controlled measuring system. For and C language based measurement functions, which uses GPIB protocol and SCPI commands. But SICL requires knowledge of BASIC and C language as well as GPIB and SCPL system. This paper introduces a new language called CALSTEP-Control and Access Language for the Systems of Test Equipment and Payload. This language is designed for the operator to perform the tests for the satellite communication system without any special knowledge that is mentioned above. This language has very limited number of commands which are to be used to control the payload system and test equipments to perform IOT and CSM, and those commands are very readable and easy to understand, so an operator without any knowledge of BASIC and C programming language, or SICL and SCPI command can use it.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.6
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• pp.756-759
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• 2012

This paper presents the multibeam service coverage of GEO(Geostationary Orbit) satellite and the practical antenna scheme scenarios to provide the universal communication services on the Korean peninsula. The proposed antenna systems consist of the simplest scheme and feed network so that they can be mounted on satellites. The feed networks are effectively organized according to the frequency and polarization plan. Despite simple structure, all scenarios meet the electrical performance by the optimization of feed allocation and feed excitation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.466-473
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• 2011

The purpose of satellite thermal control design is to maintain all the elements of a spacecraft system within their temperature limits for all mission phases. The thermal analysis model for Low Earth Orbit satellite payload level simulation is established by considering thermal vacuum test environment condition, thermal vacuum chamber configuration, and satellite's payload inner thermal environment. The established thermal analysis model is used to determine thermal vacuum test conditions and test case requirements.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.617-622
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• 2016

The article describes the determination of the dynamic stability for an observation antenna, considering the rotational speed by the payload driving motor. A finite element model of the observation antenna was made using the solid and beam elements. The connecting parts between the solid and the beam was adequately coupled. The boundary conditions were made by restriction of the degree of freedoms in the supporting points. With the comparison between the modal analysis results and the rotating speed of the payload driving motor, no resonance for the structure of antenna was identified and first natural frequency was determined under 33 Hz (Seismic Cut-Off Frequency). Therefore, the dynamic stability of the antenna was confirmed by the comparism between the seismic safety criterion and the stress results of the dynamic analysis applied the loading conditions and required response spectrum (RRS).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.7
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• pp.519-525
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• 2013

The traffic classification is a preliminary and essential step for stable network service provision and efficient network resource management. However, the payload signature-based method has a significant drawback in high-speed network environment that the processing speed is much slower than other method such as header-based and statistical methods. In this paper, We propose the server IP, Port cache-based traffic classification method using application traffic locality to improve the processing speed of traffic classification. The suggested method achieved about 10 folds improvement in processing speed and 10% improvement in completeness over the payload-based classification system.