• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.557-565
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• 2004

The Korean space program was marked by the successful launching of a KSR-III liquid propelled sounding rocket. The Inertial Navigation System (INS) which carries out critical mission functions of navigation, guidance and control was domestically developed and perfectly certified through the flight test. The system consists of a strapdown inertial measurement, an onboard computer and flight software. This paper will describes the development works of the inertial navigation system, including top level system design, hardware and software. And it summarizes flight results.

• Educational Technology International
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• v.21 no.2
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• pp.125-153
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• 2020

The advancement of virtual reality technology offers various locomotion options that support users' navigation behaviors in a virtual reality environment. This study was aimed at examining the effects of two navigation methods-joystick-controlling and walking-around-on users' perceived usability, behavioral engagement, and virtual presence. Fifty South Korean college students were recruited in the study, and they were assigned randomly to one of the two navigation conditions. Participants from each group were asked to observe a 3D object and complete the surveys. They were then asked to repeat the procedure with a 2D image. Using repeated-measures ANOVAs and MANOVA, we found that users using joystick-controlling reported higher usability and showed superior performance to the walking-around group on two tasks. Participants reported a higher behavioral engagement when observing the 2D image. Besides, they perceived a significantly higher virtual presence when observing the 2D image. Finally, we discussed the implications of the findings for the navigation method design.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.167-177
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• 2024

The Korea Augmentation Satellite System (KASS) has been certified by the Ministry of Land, Infrastructure and Transport (MOLIT) and commenced Safety-of-Life (SoL) service at the end of 2023. KASS complies with the APV-I signal-in-space performance requirements defined in the International Civil Aviation Organization (ICAO) Standards and Recommendation Practices (SARPs). The performance of KASS is verified through two steps. In the first step, design conformity from the aspect of performance is verified by both review and analysis of design and simulation. In the second step, operational conformity is tested and assessed by operational testing using real data and a deployed system with operational SWs and configurations. This paper presents a methodology, a procedure and results for the KASS operational testing. Finally, performance degradation events and results by month and region during the operational testing are presented and analyzed.

• The Journal of the Korea Contents Association
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• v.6 no.11
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• pp.202-216
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• 2006

A number of process algebras are not well suitable for real-time navigation/delivery systems due to the following reasons: 1) lack of representation of process distributivity over some geographical space and 2) the indistinction of representation of process mobility from process distributivity over the space. To make the process algebra suitable to the systems, it seems to be necessary to separate the space representation from the mobility representation. This paper presents a formal method for this purpose, namely, Calculus of Abstract Real-Time Distribution, Mobility, and Interaction (CARDMI). For analysis and verification of behavioral properties, CARDMI defines a set of the spatial, temporal and the interactive deduction rules and a set of equivalence relations. The rules and equivalences can be abstracted hierarchically due to the spatial abstraction, too. CARDMI can be applied to virtual navigation/delivery system for contents, too.

• Journal of Astronomy and Space Sciences
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• v.26 no.1
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• pp.99-110
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• 2009

The main purpose of the current research is to developments a real-time Hardware In-the-Loop (HIL) simulation testbed for the satellite formation flying navigation and orbit control. The HIL simulation testbed is integrated for demonstrations and evaluations of navigation and orbit control algorithms. The HIL simulation testbed is composed of Environment computer, GPS simulator, Flight computer and Visualization computer system. GPS measurements are generated by a SPIRENT GSS6560 multi-channel RF simulator to produce pseudorange, carrier phase measurements. The measurement date are transferred to Satrec Intiative space borne GPS receiver and exchanged by the flight computer system and subsequently processed in a navigation filter to generate relative or absolute state estimates. These results are fed into control algorithm to generate orbit controls required to maintain the formation. These maneuvers are informed to environment computer system to build a close simulation loop. In this paper, the overall design of the HIL simulation testbed for the satellite formation flying navigation and control is presented. Each component of the testbed is then described. Finally, a LEO formation navigation and control simulation is demonstrated by using virtual scenario.

• Journal of Astronomy and Space Sciences
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• v.25 no.3
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• pp.267-282
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• 2008

The GNSS (Global Navigation Satellite System) signal is delayed by the neutral atmosphere at the troposphere, so that the delay is one of major error sources for GNSS precise positioning. The tropospheric delay is an integrated refractive index along the path of GNSS signal. The refractive index is empirically related to standard meteorological variables, such as pressure, temperature and water vapor partial pressure, therefore the tropospheric delay could be calculated from them. In this paper, it is presented how to generate meteorological data where observation cannot be performed. KASI(Korea Astronomy & Space Science Institute) has operated 9 GPS (Global Positioning System) permanent stations equipped with co-located MET3A, which is a meteorological sensor. Meteorological data are generated from observations of MET3A by Ordinary Kriging. To compensate a blank of observation data, simple models which consider periodic characteristics for meteorological data, are employed.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.2
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• pp.75-85
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• 2016

The performance of up-to-date mapping functions and various mean temperature equations were analyzed to derive optimal mapping function and mean temperature equation when GNSS precipitable water vapor (PWV) was investigated in the Korean Peninsula. Bernese GNSS Software 5.2, which can perform high precision GNSS data processing, was used for accurate analysis, and zenith total delay (ZTD) required to calculate PWV was estimated via the Precise Point Positioning (PPP) method. GNSS, radiosonde, and meteorological data from 2009 to 2014 were acquired from Sokcho Observatory and used. ZTDs estimated by applying the global mapping function (GMF) and Vienna mapping function 1 (VMF1) were compared with each other in order to evaluate the performance of the mapping functions. To assess the performance of mean temperature equations, GNSS PWV was calculated by using six mean temperature equations and a difference with radiosonde PWV was investigated. Conclusively, accuracy of data processing was improved more when using VMF1 than using GMF. A mean temperature equation proposed by Wu (2003) had the smallest difference with that in the radiosonde in the analysis including all seasons. In summer, a mean temperature equation proposed by Song & Grejner-Brzezinska (2009) had the closest results with that of radiosonde. In winter, a mean temperature equation proposed by Song (2009) showed the closest results with that of radiosonde.

• Magazine of korean Tunnelling and Underground Space Association
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• v.14 no.3
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• pp.60-72
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• 2012

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.95-95
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• 2004

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.109-109
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• 2004