• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제9권3호
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• pp.77-82
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• 2020

차량에 탑재된 내비게이션의 대부분은 복잡한 구조의 PSF(Physical Storage Format) 파일 기반으로 개발되어 점증적 맵 갱신을 지원하기 어렵다. 이를 해결하기 위한 차세대 내비게이션 방법의 하나로서 DB 기반의 내비게이션 기술이 주목받고 있다. 점진적 맵 갱신을 지원하는 DB 기반 내비게이션 구현에 있어 지속적인 맵 데이터 갱신으로 인한 데이터 단편화현상으로 데이터 접근 비용이 증가할 수 있어 검색 성능의 저하가 발생할 수 있다. 본 논문에서는 점증적 맵 갱신을 지원하는 DB 기반 내비게이션의 성능 향상 방법의 하나로 데이터 단편화 방지 기법을 제시하고 실제 구현을 통하여 성능 향상 효과가 있음을 검증하였다.

• 한국콘텐츠학회논문지
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• 제11권4호
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• pp.83-91
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• 2011

지도 DB 업데이트 방법은 카 네비게이션을 사용하는 운전자 입장에서는 매우 중요한 요소이다. 본 연구는 클라우드 컴퓨팅 환경을 이용해 이기종 네비게이션 시스템을 사용하는 운전자들이 새로운 도로(Unknown Roads) 주행시 추출된 도로 속성 정보를 클라우드에서 분석해 이기종 네비게이션간 서비스가 가능한 XML 포맷의 Metadata를 생성한 다음, 이것을 모든 지도 정보 제공자(Provider)에게 제공하면 해당 Map DB 제공자는 클라우드로 부터 제공 받은 도로의 속성 정보 metadata를 자신의 네비게이션 시스템을 사용하는 모든 운전자의 Map DB를 실시간으로 업데이트하는 방법을 제안한다. 이 방법은 Map DB Provider들이 수행하는 실차 주행 테스트 비용을 줄이고 서버 자원 통합 구축을 통한 Map DB 데이터센터의 유지 비용을 줄일 수 있다. 결국 제안된 방법은 새로운 도로 정보를 모든 운전자들의 Map DB에 더욱 효율적으로 업데이트할 수 있다.

• Journal of Positioning, Navigation, and Timing
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• 제10권1호
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• pp.55-66
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• 2021

In this paper, we propose a signal propagation modeling technique for generating a positioning fingerprint DB based on Long Term Evolution (LTE) signals. When a DB is created based on the location-based signal information collected in an urban area, gaps in the DB due to uncollected areas occur. The spatial interpolation method for filling the gaps has limitations. In addition, the existing gap filling technique through signal propagation modeling does not reflect the signal attenuation characteristics according to directions occurring in urban areas by considering only the signal attenuation characteristics according to distance. To solve this problem, this paper proposes a Deep Neural Network (DNN)-based signal propagation functionalization technique that considers distance and direction together. To verify the performance of this technique, an experiment was conducted in Seocho-gu, Seoul. Based on the acquired signals, signal propagation characteristics were modeled for each method, and Root Mean Squared Errors (RMSE) was calculated using the verification data to perform comparative analysis. As a result, it was shown that the proposed technique is improved by about 4.284 dBm compared to the existing signal propagation model. Through this, it can be confirmed that the DNN-based signal propagation model proposed in this paper is excellent in performance, and it is expected that the positioning performance will be improved based on the fingerprint DB generated through it.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.157-167
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• 2020

Fingerprinting method is useful when estimating the location of a requestor based on LTE signals in an urban area. To do this, it is necessary to acquire location-based signals everywhere in the service area for fingerprint DB generation in advance. However, there may be signal uncollected area within a wide service area, which may cause a problem that the positioning accuracy of the requestor is low. In order to solve this problem, in this paper, signal propagation modeling is performed based on the obtained measurements, and based on this model, the signal information in the non-acquisition region is estimated. To this end, techniques for modeling signal propagation according to a method using measurements are proposed. The performance of the proposed techniques is verified based on the measurements obtained on a test bed selected as Seocho-gu, Seoul. As a result, it can be seen that signal propagation modeling performed based on multidivision segmented measurements has the most performance improvement.

• 한국측량학회지
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• 제33권6호
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• pp.569-577
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• 2015

The navigation algorithm developed based on the extended Kalman filter (EKF) sometimes diverges when the linearity between the measurements and the states is not preserved. In this study, new update conditions together with two conditions from previous study for gravity gradient referenced navigation (GGRN) were deduced for the filter performance. Also, the effect of each update conditions was evaluated imposing the various magnitudes of the database (DB) and the sensor errors. In case the DB and the sensor errors were supposed to 0.1 Eo and 0.01 Eo, the navigation performance was improved in the eight trajectories by using part of gravity gradient components that independently estimate states located within trust boundary. When applying only the components showing larger variation, around 200% of improvement was found. Even the DB and sensor error were supposed to 3 Eo, six update conditions improved performance in at least seven trajectories. More than five trajectories generated better results with 5 Eo error of the DB and the sensor. Especially, two update conditions successfully control divergence, and bounded the navigation error to the 1/10 level. However, these update conditions could not be generalized for all trajectories so that it is recommended to apply update conditions at the stage of planning, or as an index of precision of GGRN when combine with various types of geophysical data and algorithm.

• 한국측량학회지
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• 제34권4호
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• pp.373-382
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• 2016

In this study, an EKF (Extended Kalman Filter) based database reference navigation using both gravity gradient and terrain data was performed to complement the weakness of using only one type of geophysical DB (Database). Furthermore, a new algorithm which combines the EKF and profile matching was developed to improve the stability and accuracy of the positioning. On the basis of simulations, it was found that the overall navigation performance was improved by the combination of geophysical DBs except the two trajectories in which the divergence of TRN (Terrain Referenced Navigation) occurred. To solve the divergence problem, the profile matching algorithm using the terrain data is combined with the EKF. The results show that all trajectories generate the stable performance with positioning error ranges between 14m to 23m although not all trajectories positioning accuracy is improved. The average positioning error from the combined algorithm for all nine trajectories is about 18 m. For further study, a development of a switching geophysical DB or algorithm between the EKF and the profile matching to improve the navigation performance is suggested.

• 한국측량학회지
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• 제32권1호
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• pp.63-73
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• 2014

최근 의도적인 간섭 또는 전파교란으로 인한 위성기반항법시스템(GNSS)의 정확도 저하 문제가 대두되면서 GNSS를 사용할 수 없는 환경에 대응할 수 있는 항법 기술 중 하나로 데이터베이스(DB)를 기반으로 한 항법 연구가 진행되고 있다. 본 연구에서는 지구물리 DB 중 중력구배를 선정하여 우리나라 중력구배 DB를 구축하고, 확장형칼만필터(EKF)를 적용하여 중력구배기반 항법을 구현하였다. 항법 성능은 시뮬레이션을 통해 분석하였으며, 우리나라 전역에 14개의 비행궤적을 생성한 후 다양한 DB와 센서 오차, 그리고 고도에 따른 영향을 고려하였다. 비행성능을 분석한 결과 DB와 센서 오차가 작을수록, 고도가 낮을수록 정밀한 항법이 가능함을 확인하였다. 또한, DB 기반의 항법시스템 중 가장 널리 알려진 지형참조 항법과 상대적인 성능 분석을 수행한 결과, 고도가 낮은 경우는 DB 및 센서 오차와 무관하게 대체로 중력구배기반 항법이 우수한 성능을 나타내었다. 그러나 고도가 높아지면 높은 정밀도의 중력구배계와 중력구배 DB를 탑재한 경우에만 지형참조 항법의 결과와 유사한 수준의 항법이 가능하였다. 본 연구에서 고려한 DB와 센서 오차, 고도 외에도 DB 해상도, 비행속도 및 갱신 주기 등 중력구배기반 항법에 영향을 미치는 다양한 요인이 있으므로 이를 고려한 분석이 추가로 수행되어야 할 것이다.

• Journal of Positioning, Navigation, and Timing
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• 제9권3호
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• pp.151-156
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• 2020

A technology for calculating the position of a device is very important for users who receive positioning services, regardless of various indoor/outdoor or with/without any positioning infrastructure existence environments. One of the positioning resources widely used at present, LTE, is a typical infrastructure that can overcome the space limitation, however its positioning method based on the position of the LTE base station has low accuracy. A method of constructing a radio wave map of an LTE signal has been proposed as a method for overcoming the accuracy, but it takes a lot of time and cost to perform high-density collection in a wide area. In this paper, we describe a method of creating a high-density DB for the entire region by using vehicle-based partial collection data. To create a positioning database, we applied the idea of Generative Adversarial Network (GAN), which has recently been in the spotlight in the field of deep learning, and learned the collected data. Then, a virtually generated map which having the smallest error from the actual data is selected as the optimum DB. We verified the effectiveness of the positioning DB generation algorithm using the positioning data obtained from un-collected area.

• 한국항해항만학회지
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• 제43권5호
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• pp.302-309
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• 2019

This study introduces the navigational environment database(DB) compiling water depth, sediment type and marine managed areas (MMAs) in coastal waters of South Korea. The water depth and sediment data were constructed by combining their sparse points of electronic navigation chart and survey data with high spatial resolution using the inverse distance weighting and natural neighbor interpolation method included in ArcGIS. The MMAs were integrated based on all shapefiles provided by several government agencies using ArcGIS because the areas should be used in an emergency case of ship. To test the validity of the constructed DB, we conducted a test application for grounding and anchoring zones using a ship accident case. The result revealed each area of possible grounding candidates and anchorages is calculated and displayed properly, excluding obstacle places.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.737-740
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• 2001

본 논문에서는 선박의 더 효율적이고 안전한 운항과 인력 및 에너지 절감을 위하여 PC를 기반으로 한 SPS (Secondary Planning System)를 개발하였으며, SPS를 중심으로 구성한 항해 자동화 시스템을 제안하였다. 개발된 SPS는 항해 선박의 각종 항해통신장비의 이상유무를 모니터링 하는 기능을 수행하며, 운항정보시스템(GIS), 전자해도시스템(ECDIS), 또는 Radar/ARPA장비에 이상 상태가 발생되었을 때 해당장비의 주요핵심 정보와 기능을 자동으로 대체함으로 해상사고의 방지와 선박의 항해 시스템의 효율성과 안정성을 높일 수 있다. 또한 SPS는 항해통신장비의 보조장비 기능인 DB Server 기능과 Network Server기능도 가진다.