• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.410-418
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• 2018

This paper describes the design, analysis, and verification tests of the Dual-axis X-band antenna pointing mechanism(XAPM) that has been developed for the Earth observation mission at low Earth orbits. Based on the experience of development and operation of the similar system, we defined the main points and requirements of the system design and confirmed the characteristics of the system through the verification test of the launch and orbit environment test of the engineering qualification model. Through the characteristics and verification techniques of the system acquired during this process, improvement points of the later qualification model are derived.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.2
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• pp.12-20
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• 2007

The aiming ability is a key to improve the accuracy performance of the gun pointing system in the ground military vehicle. This paper describes the new detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis the vibration trends of the pointing system occurred while the vehicle driving, acceleration data obtained from vehicle was processed by using data processing algorithm with moving average and Hilbert transform. The specific mode constants of acceleration were obtained from various disturbances. Vehicle velocity, road condition and property of pointing structure were considered as factors which make the change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition of the classification of vibration signal in various driving conditions. Results of signal processing were compared with other condition result and analysed.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.595-600
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• 2006

GOCI is the core paryload of the geostationary satellite COMS(Communication, Ocean and Meteological Satellite) for ocean monitoring. It is scheduled to be launched at the end of 2008. GOCI observes ocean color around the Korean Peninsula over $2500km\times2500km$ area. It used tilted two-axis scan mechanism to observe entire field of view. In this work, the pointing stability of the tilted two-axis method is analyzed and compared with that of gimbal method. The analysis results show that tilted two-axis method gives great stability and it is adequate for geostationary payload. The results can also be used to determine and analyze the mechanism specifications.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.62-70
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• 2007

The aiming ability is a to improve accuracy performance of the firing vehicle. This paper describes the detection method of chatter vibration using disturbance acceleration in the pointing structure. In order to analysis vibration trends of the pointing system occurred during vehicle drive, acceleration data was processed by using data processing algorithm with moving average and Hilbert transform. Specific mode constants of acceleration were obtained under various disturbances. Vehicle velocity, road condition, property of pointing structure were considered as factors which make change of vibration trend in vehicle dynamics. Finally, back propagation neural networks have been applied to the pattern recognition for the classification of vibration signal in various driving conditions. Results of signal processing were compared and analysed.

• KIISE Transactions on Computing Practices
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• v.22 no.12
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• pp.625-631
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• 2016

Pointer Networks is a model which generates an output sequence with elements that correspond to an input sequence, based on the attention mechanism. A time complexity of the pointer networks is $O(N^2)$ resulting in longer decoding time of the model. This is because the model calculates attention for each input, if size of the input sequence is N. In this paper, we propose the pointer networks based on skip pointing model, which confirms the necessary input vector at decoding for reducing the decoding time of the pointer networks. Furthermore, experiments were conducted for the pronouns coreference resolution, which uses the method proposed in this paper. Our results show that the processing time per sentence was approximately 1.15 times faster, and the MUC F1 was 83.60%; this was approximately 2.17% improvement and a better performance than the original pointer networks.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.440-443
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• 2004

As a main management unit of MSC, PMU controls the MSC payload operation by issuing commands to other subunit and PMU internal modules. One of these main control functions is to drive the APS(Antenna Pointing System) when APS motion is required. For this purpose, SBC(Single Board Computer) for calculating motor commands and APDE for driving APM(Antenna Pointing Mechanism) by PWM signal operate inside PUM. In this paper, details on APDE design shall be described such as electronic board architecture, primary and redundant design concept, Cross-Strap, FPGA contents and latch-up immune concept, etc., which shall show good practices of electronic board design for space program.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.512-514
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• 2004

The Electro-Optical Camera (EOC) is a high spatial resolution, visible imaging sensor which collects visible image data of the earth's sunlit surface and is the primary payload on KOMPSAT-l. The purpose of the EOC payload is to provide high resolution visible imagery data to support cartography of the Korean Peninsula. The EOC is a push broom-scanned sensor which incorporates a single nadir looking telescope. At the nominal altitude of 685Km with the spacecraft in a nadir pointing attitude, the EOC collects data with a ground sample distance of approximately 6.6 meters and a swath width of around 17Km. The EOC is designed to operate with a duty cycle of up to 2 minutes (contiguous) per orbit over the mission lifetime of 3 years with the functions of programmable gain/offset. The EOC has no pointing mechanism of its own. EOC pointing is accomplished by right and left rolling of the spacecraft, as needed. Under nominal operating conditions, the spacecraft can be rolled to an angle in the range from +/- 15 to 30 degrees to support the collection of stereo data. In this paper, the status of EOC such as temperature, dark calibration, cover operation and thermal control is checked and analyzed by continuously monitored state of health (SOH) data and image data during the mission life of 3 years. The aliveness of EOC and operation continuation beyond mission life is confirmed by the results of the analysis.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.89-95
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• 2003

In this study, the technical characteristics of geosynchronous multi-mission satellites are investigated, compared to communication satellites. Geosynchronous meteorological satellites, whose imaging data is normally shared with the international society, have large coverage for monitoring and data service. Also the higher pointing accuracy is requested to keep the spatial resolution of 1-4km, compared to those of communication satellites. Cryogenic thermal control is needed for the better performance of IR sensors and the contamination protection of optical parts should be considered. On the other hands, for the successful development of the multi-mission satellite COMS, which will be launched in 2008, the special features of attitude control, electrical power, thermal control and mechanism are investigated.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.195-198
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• 2007

GOCI(Geostationary Ocean Color Imager) is the core paryload of the geostationary satellite COMS(Communication, Ocean and Meteological Satellite) for ocean monitoring. It is scheduled to be launched at the end of 2008. GOCI observes ocean color around the Korean Peninsula over $2500km{\times}2500km$ area. Whole field of view is divided into 16 solts and scan mechanism enables to point each slot position. Tilted two-axis scan method is used to observe entire field of view with great pointing stability. Vignetting of the optical system appears when the partial obscuration by intermediate optical components occurs. It leads to the variation of the illumination in the image and gradual fading near the edge of the field. It should be prohibited for the stable radiometric performances. In this work, vignetting analysis of GOCI optical system is performed. For the systematic approach, GOCI optical system is divided into scan mechanism part and telescope part. Vignetting analysis of each part is performed and each result is combined for the overall vignetting performances. The analyzed results can be applied to the selection of slot acquisition angle of scan mechanism to minimize vignetting effects.

• Earthquakes and Structures
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• v.8 no.5
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• pp.1191-1214
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• 2015

The Theory of Plastic Mechanism Control (TPMC) has been recently extended to the case of Eccentrically Braced Frames (EBFs) with inverted Y-scheme, i.e., EBFs with vertical links. In this paper a further validation of the design procedure, based on TPMC, is provided by means of Incremental Dynamic Analyses (IDA) pointing out the fulfilment of the design goal, i.e., the development of a pattern of yielding consistent with the collapse mechanism of global type where all the links are yielded and all the beams are yielded at their ends while all the columns and the diagonal braces remain in elastic range with the only exception of the base sections of first storey columns. In particular, a study case is designed according to both TPMC and Eurocode 8 provisions and the corresponding seismic performances are investigated by both push-over and IDA analyses. The results show the different performances obtained in terms of pattern of yielding, maximum interstorey drift, link plastic rotation demand and sharing of the seismic base shear between the moment-resisting part and the bracing part of the structural system. The seismic performance improvement obtained by means of TPMC, compared to Eurocode 8 provisions, is pointed out.