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Trends of Open PPP/PPP-RTK Correction Services (Open PPP/PPP-RTK 보정정보 서비스 동향)

  • Cheolsoon Lim;Yongrae Jo;Yebin Lee;Yunho Cha;Byungwoon Park;Dookyung Park;Seungho Lee
    • Journal of Advanced Navigation Technology
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    • v.26 no.6
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    • pp.418-426
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    • 2022
  • Unlike OSR(observation space representation), the SSR(state space representation) augmentation system is suitable for a one-way broadcasting service because it provides the same corrections to all users in the service area. Due to this advantage, several GNSS(global navigation system) systems such as Galileo, BDS(beidou navigation satellite system), QZSS(quasi zenith satellite system) are establishing PPP (precise point positioning)/PPP-RTK precision positioning services based on SSR messages. Therefore, in this paper, we try to understand the trends of satellite-based PPP/PPP-RTK correction services by analyzing the system configurations, characteristics, and precise positioning performance of satellite-based SSR correction broadcasting services.

다목적 위성 2호 MSC 영상 자료를 위한 검보정 target 준비

  • 이동한;송정헌;김용승
    • Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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    • 2004.03a
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    • pp.255-259
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    • 2004
  • 본 논문에서는 다목적 위성 2호의 주 탑재체인 MSC (Multi-Spectral Camera)의 영상자료 검보정을 위한 검보정 target 준비 작업에 대해 설명한다. MSC 영상 자료에 대한 검보정 작업은 다목적 위성 2호의 발사 후 초기 운영 기간 (LEOP: Launch and Early Operation Phase)인 3개월 동안 수행될 예정이다. 위성 발사 전까지 MSC 영상 자료에 대한 검보정을 수행하기 위해 필요한 준비 작업들이 현재 한국항공우주연구원에서 진행중이다. LEOP 기간 동안 MSC 영상 자료를 검보정하기 위해서, MSC의 센서 특성에 따라 7가지 정도의 검보정 target에 대한 설계 초안이 완성되었으며, 향후 target에 대한 설계를 완성한 후에 2004년 중에 한 두 부지에 몇 가지 target들을 건설하고, 다목적 위성 2호의 궤도 특성을 고려하여 일부 target은 운반이 가능하도록 제작할 예정이다. 검보정 target이 촬영된 MSC 영상 자료의 분석을 통해, GSD (Ground Sample Distance), Aliasing, Linearity, Edge Slope & Response, MTF (Modulation Transfer Function), FOV & IFOV, Absolute radiometric validation, Position Accuracy 등의 MSC 검보정 요소 값들을 측정할 계획이다.

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Performance Verification of Psudolite-based Augmentation System Using RF signal logger and broadcaster (RF 신호 수집/방송 장치를 활용한 의사위성 기반 광역보정시스템의 후처리 성능 검증)

  • Han, Deok-Hwa;Yun, Ho;Kim, Chong-Won;Kim, O-Jong;Kee, Chang-Don
    • Journal of Navigation and Port Research
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    • v.38 no.4
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    • pp.391-397
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    • 2014
  • Wide Area Differential GNSS(WA-DGNSS) was developed in order to improve the accuracy and integrity performance of GNSS. In this paper, overall structure of Pseudolite-Based Augmentation System(PBAS) and experimental methods which enables the post-processing test with commercial receiver will be described. For generating augmenting message, GPS measurement collected from five NDGPS reference stations were processed by reference station S/W and master station S/W. The accuracy of augmenting message was tested by comparing SP3, IONEX data. In the test, RF signal of user was collected and correction data were generated. After that, RF signal was broadcasted with pseudolite signal. Test was conducted using three commercial receiver and the performance was compared with MSAS and standalone user. From the position output of each receiver, it was shown that improved position was obtained by applying augmenting message.

Development of Template Compensation Algorithm for Interoperable Fingerprint Recognition using Taylor Series (테일러시리즈를 이용한 이기종 지문 센서 호환 템플릿 보정 알고리즘 개발)

  • Jang, Ji-Hyeon;Kim, Hak-Il
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.18 no.4
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    • pp.93-102
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    • 2008
  • Fingerprint sensor interoperability refers to the ability of a system to compensate for the variability introduced in the finger data of individual due to the deployment of different sensors. The purpose of this paper is the development of a compensation algorithm by which the interoperability of fingerprint recognition can be improved among various different fingerprint sensors. In this paper we show that a simple transformation derived to form a Taylor series expansion can be used in conjunction with a set of corresponding minutia points to improve the correspondence of finer fingerprint details within a fingerprint image. This is demonstrated by an applying the transformation to a database of fingerprint images and examining the minutiae match scores with and without the transformation. The EER of the proposed method was improved by average 60.94% better than before compensation.

Methodology of Correcting Barometer Using Moving Drone and RTK Receiver (동적 드론과 RTK 수신기를 이용한 기압계 보정정보 생성 방법론)

  • Kim, Suyeol;Yun, Jeonghyeon;Park, Byungwoon
    • Journal of Advanced Navigation Technology
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    • v.26 no.2
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    • pp.63-71
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    • 2022
  • Barometers have been used to calculate altitude, and with the development of technology, barometer which had a large volume have now been reduced to about centimeter-level. The altitude calculation using barometer is proceeded using the relationship between reference sea level pressure and the pressure obtained by barometer, and for this, pre-calibration of the barometer is essential. In addition, the barometer has a certain level of bias from actual pressure due to production, and many smartphone manufacturers correct it during the manufacturing process, but it is difficult to correct errors caused by environmental variables. In this paper, we extended methodology of correcting barometer using static reference station to moving drone, and it was possible to calculate the altitude more accurately.

Secret key information reconciliation protocol using LDPC code (LDPC 부호를 이용한 암호키 정보 보정 프로토콜)

  • Lee, Sunghoon;Heo, Jun
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2014.11a
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    • pp.228-229
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    • 2014
  • 양자 키 분배는 안정한 통신을 위해 고안된 암호 체계이다. 양자 키 분배의 후처리 과정 중 정보 보정은 두 적법한 사용자 간의 연관 관계가 있는 정보를 일치시키는 과정이다. 고전 오류 정정 과정과 비슷하며 이 과정을 위해 추가 정보를 주고받기 때문에 도청자에게 일정량의 정보가 노출된다. 따라서 정보 보정 프로토콜에서 노출된 정보량은 프로토콜의 성능을 결정하는 중요한 요인이 된다. 본 논문에서는 Winnow 프로토콜과 LDPC 부호를 이용한 프로토콜을 노출된 정보량과 평균 통신 횟수 측면에서 비교한다. 그 결과로 Winnow 프로토콜에 비해 LDPC 부호를 이용한 프로토콜이 현재 양자 키 분배 시스템에서 더 좋은 기술이 될 수 있음을 보인다. 또한 LDPC 부호를 이용한 프로토콜이 가지는 단점을 극복할 수 있는 향후 연구 방향을 제시한다.

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별 추적기의 성능향상을 위한 광행차 보정에 대한 연구

  • 용기력;김응현;이선호;오시환;최홍택;이승우
    • Bulletin of the Korean Space Science Society
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    • 2003.10a
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    • pp.68-68
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    • 2003
  • 본 논문은 별 추적기의 여러 가지의 성능변수 중에 광행차가 성능에 미치는 영향을 연구하였다. 일반적으로 광행차는 별 추적기의 저주파오차로 작용하며, 별 추적기 좌표계에서 최대 27" 정도의 성능을 감소시킨다. 지구가 태양 주위를 공전함으로써 야기되는 광행차는 약 21"이며, 줄리안 데이트를 통해서 보정이 가능하며, 관성 좌표계에서 지구 저궤도 위성이 궤도운동을 함으로 야기되는 광행차 오차는 약 6" 이며, 궤도정보를 통해서 보정이 가능하다. 이를 보정하기 위해서, 보정 알고리즘을 구현하여 다목적 실용위성 자세제어계 성능해석 소프트웨어를 통해서 검증을 하였다.

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A study on Improvement of Web-based Diagnosis-Supplement System for Basic Academic Skills (웹 기반 기초학력 진단-보정 시스템의 개선 방안 도출)

  • Jeon, Soo-Jin;Kim, Han-Sung
    • Journal of The Korean Association of Information Education
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    • v.20 no.5
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    • pp.487-498
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    • 2016
  • The Ministry of Education has serviced nationwide the diagnosis-supplement system for basic academic skills for elementary and middle schools since 2013. The purpose of this paper is to propose an improvement plans of the diagnosis-supplement system by analysing system utilization status, 2015 and requirements of teachers and experts. For this study, over three times the taking rates and achievement rates were analyzed and the interviews and consultations of teachers and professionals were also analyzed. In conclusion, we proposed the improvement plans of the diagnosis-supplement system for the each of teachers and students.

Adaptive Retinex Back-light Compensation Algorithm Using Skewness Information of Image (영상에서 비대칭도 정보를 이용한 적응적인 Retinex 역광 보정 알고리즘)

  • Jeong, Jae-Hyun;Kang, Duk-Goo;Hong, Min-Cheol
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.8C
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    • pp.497-504
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    • 2011
  • This paper presents an adaptive retinex algorithm, In order to solve typical problems of retinex algorithm such as expensive computational cost, halo artifact, and color distortion, a function of skewness that represents a statistical distribution of pixels is defined to compensate contrast and color distortion. The experimental results show that the proposed algorithm leads to subjectively better performance than typical retinex algorithm, and that the proposed algorithm has the capability to reduce approximately 40% computational cost than typical retinex algorithm.

Half-Pixel Correction for MPEG-2/H.264 Transcoding (DCT 기반 MPEG-2/H.264 변환을 위한 1/2 화소 보정)

  • Kwon Soon-young;Lee Joo-kyong;Chung Ki-dong
    • Journal of KIISE:Software and Applications
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    • v.32 no.10
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    • pp.956-962
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    • 2005
  • To improve video quality and coding efficiency, H.264/AVC adopts different half pixel calculating method compared with the previous standards. So, the transcoder requires additional works to transcode the pre-coded video contents with the previous standards to H.264/AVC in DCT domain. In this paper, we propose the first half-pixel correction method for MPEG-2 to H.264 transcoding in DCT domain. In the proposed method, MPEG-2 block is added to the correction block obtained by difference calculation of half-pixel values between two standards using DCT reference frame. Experimental results show that the proposed achieves better quality than pixel based cascaded transcoding method.