• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1211-1215
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• 2005

In the GPS attitude determination system, the baseline length constraints can be used efficiently to reduce the search space. It is possible by adopting the assumptions that the baseline length doesn't change and the true baseline length is precisely known. But in real situation, the baseline length might be changed by many reasons and it is impossible to measure the true baseline length because there exists measurement error and antenna phase centre movement. In order to analyze the effect of the baseline length accuracy, one needs to know the relation between the accuracy of the baseline length and success rates of the integer ambiguity resolution. In this paper, the effect of the baseline length accuracy to the integer ambiguity resolution in the attitude determination system is analyzed by empirical method. The results show that the margins in the baseline length accuracy is less than a few cm which implies that one should take great cares when applying the attitude determination system to the flexible structures.

• International Journal of Control, Automation, and Systems
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• 제4권3호
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• pp.333-343
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• 2006

In this paper, the baseline-length information is directly modeled as a measurement for the Wald test, which speeds up the resolution convergence of the integer ambiguity of GPS carrier phase measurements. The convergent speed improvement is demonstrated using numerical simulation and real experiments. It is also shown that the integer ambiguities can be resolved using only four actual satellite measurements with very reasonable convergence speed, if the baseline-length information is used just like one additional observable satellite measurement. Finally, it is shown that the improvement of convergence speed of the Wald test is due to the increase of the probability ratio with the use of the baseline-length constraint.

• 한국항행학회논문지
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• 제24권6호
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• pp.540-548
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• 2020

본 논문에서는 기선 거리에 따른 VRS (virtual reference station)와 FKP (flächen korrektur parameter) 방식의 Network RTK (real time kinematics) 사용자 성능을 비교 분석하였다. 이를 위해 현재 국토지리정보원에서 운영 중인 VRS 및 FKP 서비스를 통해 기선 거리 별 보정정보를 취득하여 상용 수신기에 적용한 후, RTK 수행 결과를 측정치 영역과 위치 영역에서 각각 분석하였다. VRS의 경우, 사용자가 기선 거리가 증가함에 따라 발생하는 공간이격 오차를 보상하지 못하므로 전반적인 RTK 성능이 저하되는 것을 확인하였다. 반면, FKP는 VRS와 달리 전리층 및 비전리층 오차의 구배를 이용하여 사용자와 기준국 간 측정치의 공간이격 오차를 보상하므로 기선 거리 약 130 km 수준까지는 기선 거리 증가하더라도 VRS에 비해 안정적인 RTK 성능을 보여주었지만, 150 km이상의 장기저선의 경우에는 FKP 보정정보의 성능 감소로 인해 미지정수 오결정 등의 문제가 발생하였다.

• Journal of Periodontal and Implant Science
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• 제36권2호
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• pp.427-434
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• 2006

The form of furcation influence both the pathogenesis of periodontal destruction and therapeutic results. The present study was performed to evaluate the effect of root trunk length on clinical outcomes of guided tissue regeneration. Total 30 mandibular first molars were evaluated in this study. Probing pocket depth, clinical attachment level, vertical defect depth and horizontal defect depth were measured at baseline and 6 month after GTR. Correlation coefficients between root trunk length and other clinical measurement were analyzed. The results of this study were as follows 1. The mean root trunk length in lower 1st molar was 2.15 mm. 2. Probing pocket depth, clinical attachment level, vertical defect depth and horizontal defect depth were significantly reduced at 6 month postoperatively compared to values of baseline 3. Correlation coefficient between root trunk length and vertical defect depth at baseline was 0.406 showing the positive correlation 4. Correlation coefficient between root trunk length and horizontal defect depth at baseline was -0.463 showing the negative correlation. 5. Correlation coefficient between root trunk length and decrease of horizontal defect depth after GTR was 0.654 showing the positive correlation. In conclusion, the root trunk length maybe effector for clinical outcome after guided tissue regeneration.

• International Journal of Aeronautical and Space Sciences
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• 제16권1호
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• pp.89-101
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• 2015

To satisfy civil aviation requirements using the Global Navigation Satellite System (GNSS), it is important to guarantee system integrity. In this work, we propose a fault detection algorithm for GNSS ephemeris anomalies. The basic principle concerns baseline length estimation with GNSS measurements (pseudorange, broadcasted ephemerides). The estimated baseline length is subtracted from the true baseline length, computed using the exact surveyed ground antenna positions. If this subtracted value differs by more than a given threshold, this indicates that an ephemeris anomaly has been detected. This algorithm is suitable for detecting Type A ephemeris failure, and more advantageous for use with multiple stations with various long baseline vectors. The principles of the algorithm, sensitivity analysis, minimum detectable error (MDE), and protection level derivation are described and we verify the sensitivity analysis and algorithm availability based on real GPS data in Korea. Consequently, this algorithm is appropriate for GNSS regional implementation.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.625-627
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• 2003

In this study, the Global Positioning System (GPS) data collected by the GPS receivers that were established as continuously operating reference stations by Central Weather Bureau and Industrial Technology Research Institute of Taiwan are utilized to investigate the impact of atmospheric water vapor on GPS positioning determination. The surface meteorological measurements that were concurrently acquired by instruments co-located with the GPS receivers include temperature, pressure and humidity data. To obtain the influence of the baseline length on the proposed impact study, four baselines are considered according to the locations of the permanent GPS sites. The length of the shorter baseline is about 66km, while the longer is about 118 km. The results from the studies associated with different baseline lengths and ellipsoid height were compared for the cases with and without a priori knowledge of surface meteorological measurements. The finding based on 66 days measurements is that the surface meteorological measurements have a significant impact on the positioning determination for the longer baseline case. The associated daily maximum differences are 1.1 cm and 1.4 cm for the baseline and ellipsoid height respectively. The corresponding biases are -8.1 mm in length and -7.3 mm in el lipsoid height.

• 한국측량학회지
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• 제21권2호
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• pp.123-129
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• 2003

본 논문에서는 동일한 GPS 측량 데이터를 Bernese GPS 소프트웨어로 기선 해석한 결과와 범용 상용 소프트웨어로 기선 해석한 결과를 비교 분석하였으며 장기선 데이터 처리시 고려해야 할 사항들을 검토하였다. Bernese GPS 소프트웨어로 장기선 데이터 처리시 기선 거리에 따른 편차가 거의 없는데 비해 범용 상용 소프트웨어로 장기선 데이터 처리시에는 기선 거리에 비례하여 편차가 발생하였다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 춘계학술발표회논문집
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• pp.125-130
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• 2004

As an application of GPS is increased by world geodetic system introduction gradually, in this time, It is increased necessary of GPS baseline analysis program development. In this study, I developed a baseline analysis program by L1/L2 carrier. And I compared a baseline analysis result with a commercial program. I showed precision of approximately ${\pm}$1cm in a baseline length in case of Narrow lane as a result that a baseline analysised a developed program.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.243-246
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• 2006

This study investigates the improvement in the theoretical success rate of the integer ambiguity resolution in GPS/GNSS carrier-phase positioning by using many visible satellites. It estimates the dependence of the rate on the baseline length in relative positioning under the condition of the use of double/triple-frequency navigation signals. The calculation results show that the use of 14 navigation satellites (i.e., seven GPS and seven Galileo ones) remarkably improves the success rate under the condition of very short baseline length, compared with the use of seven GPS ones. The numerical reliability of the calculated success rates is strictly tested by examining the tightness of the union and minimum-distance bounds to the rate. These bounds are also shown to be effective to investigate the realization of the high success rates.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.247-250
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• 2006

Based on the possibility theory and the fuzzy set, the Maximum Possibility Estimation method and its applications in kinematic GPS positioning are presented in this paper. Firstly, the principle and the optimal criterion of the Maximum Possibility Estimation method are explained. Secondly, the kinematic GPS positioning model of single epoch single frequency with baseline length constraint is developed. Then, the authors introduce the artificial immune algorithm and use this algorithm to search the global optimum of the Maximum Possibility Estimation model. The results of some examples show that the method is efficient for kinematic GPS positioning.