• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.2090-2101
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• 2015

We propose a robust tracking method that combines the merits of ACM(active contour model) and the color-based PF(particle filter), effectively. In the proposed method, PF and ACM track the color distribution and the contour of the target, respectively, and Decision part merges the estimate results from the two trackers to determine the position and scale of the target and to update the target model. By controlling the internal energy of ACM based on the estimate of the position and scale from PF tracker, we can prevent the snake pointers from falsely converging to the background clutters. We appled the proposed method to track the head of person in video and have conducted computer experiments to analyze the errors of the estimated position and scale.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.489-492
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• 2015

사용자의 위치기반 서비스에 대한 수요가 증가함에 따라 보행자의 현재 이동경로와 위치를 나타내는 '보행자 항법 시스템(PDR, Pedestrian Dead Reckoning)'에 관한 많은 연구들이 진행 중이다. 보행자 관성 항법 시스템은 IMU를 통해 데이터를 수신하여 각속도와 가속도 값을 구하고, 이 값을 토대로 사용자의 속도와 위치를 추정 한다. 또한 Zero-velocity(영속도)검출을 통해 누적되는 오차를 보정한다. 지금까지 대부분의 보행자 관성항법 시스템의 성능평가는 보행속도가 느리고 제한적인 상황에서 수행되었다. 하지만 이러한 상황은 보행자의 실제 보행상태를 반영하지 못한다. 본 논문에서는 다양한 보행속도에 따른 관성 항법 시스템의 성능을 실험하고 결과를 분석한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.499-505
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• 2016

In this Paper, we propose a body-area localization technique based on WUSB (Wireless USB) over WBAN (Wireless Body Area Networks) protocol required for wearable computer systems. The proposed localization algorithm is executed on the basis of WUSB over WBAN protocol at each sensor node comprising peripherals of a wearable computer system. To increase the accuracy of input information through various body motions in wearable computer systems, a new localization technique with high precision must be developed. To achieve the goal, This paper proposes a combined TDoA/FDoA/AoA (Time Of Arrival/Time Difference Of Arrival/Angle Of Arrival) localization technique with more than four WUSB over WBAN devices to estimate body-area location accurately. The combined TDoA/FDoA/AoA technique reduces 10mm in location estimation errors comparing with a combined TDoA/FDoA technique. This performance enhancement in location error reduction can be ignored at other systems but is meaningful results in body-area localization-based communications.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.193-195
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• 2011

GPS는 높은 정확도를 갖지만 신호 간섭에 취약하다. 따라서 Loran-C의 정확도를 개선한 eLoran이 GPS의 보조항법 시스템으로 고려되고 있다. 본 논문에서는 eLoran/GPS 통합 항법 알고리즘에서 eLoran의 오차 요소인 ASF를 보상하는 방법에 따른 위치추정 결과의 정확도를 분석한다.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.25.2-25.2
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• 2011

의상고성(儀象考成)에 수록된 항성황적경위도표(恒星黃赤經緯度表)는 청대(靑代) 흠천감(欽天監) 감정(監正)이었던 대진현(戴進賢, Ignatius Koegler, 1680-1746)이 3083개의 별들의 위치와 등급을 수록하여 1752년에 출판한 성표이다. 우리는 Yale Bright Star Catalogue 5차본을 이용하여 의상고성에 실린 별들을 동정하였다. 동정의 결과를 통해 성표의 정확도를 파악하였고, 일부 데이터가 오기되었거나 중복 기록되었음을 확인하였다. 그리고 황경에 따른 황위의 오차 분포를 통해 당시에 황적도 좌표 변환에 사용된 황도 경사각 값을 추정하였다.

• Information and Communications Magazine
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• v.34 no.4
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• pp.17-24
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• 2017

본고에서는 저가형 관성 센서를 이용하여 실내 항법을 수행하는 여러 방법들에 대해 알아본다. 저가형 관성 센서를 이용한 추측 항법은 휴대성이 뛰어나고 외부의 인프라 없이 구현이 가능하고 가격이 저렴하다는 장점이 있지만, 오차가 빠르게 누적된다는 단점이 있다. 이를 해결하기 위해 사용자의 보행 특성을 이용한 보행자 추측 항법이 제안되었다. 본고에서는 보행자 추측 항법의 두 분류 기법인 걸음-이동방향 결합 기법과 관성 항법-영속도 보정 결합 기법의 원리와 각 기법들의 기술 동향에 대해 다루고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.8-9
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• 2021

중파대역의 전파는 지표면을 따라 전파되는 지표파와 전리층에 반사되어 전파되는 공간파가 있다. 중파 R-Mode는 TOA추정을 통해 위치를 결정한다. 전리층에 반사되는 공간파를 수신할 경우 TOA 오차는 커질 수밖에 없다. 측위 정확도 향상을 위해 안테나 기반 중파 R-Mode의 수신성능을 향상하는

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.3
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• pp.195-202
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• 2007

The normalized difference in incident solar energy between a target surface and a level surface (overheating index, OHI) is useful in eliminating estimation error of site-specific maximum temperature in complex terrain. Due to the complexity in its calculation, however, an empirical proxy variable called northern exposure index (NEI) which combines slope and aspect has been used to estimate OHI based on empirical relationships between the two. An experiment with real-world landscape and temperature data was carried out to evaluate performance of the NEI - derived OHI (N-OHI) in reduction of spatial interpolation error for daily maximum temperature compared with that by the original OHI. We collected daily maximum temperature data from 7 sites in a mountainous watershed with a $149 km^2$ area and a 795m elevation range ($651{\sim}1,445m$) in Pyongchang, Kangwon province. Northern exposure index was calculated for the entire 166,050 grid cells constituting the watershed based on a 30-m digital elevation model. Daily OHI was calculated for the same watershed ana regressed to the variation of NEI. The regression equations were used to estimate N-OHI for 15th of each month. Deviations in daily maximum temperature at 7 sites from those measured at the nearby synoptic station were calculated from June 2006 to February 2007 and regressed to the N-OHI. The same procedure was repeated with the original OHI values. The ratio sum of square errors contributable by the N-OHI were 0.46 (winter), 0.24 (fall), and 0.01 (summer), while those by the original OHI were 0.52, 0.37 and 0.15, respectively.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.1-7
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• 2007

When the sensor geometry is poor, the user position estimate obtained by of GN (Gauss-Newton) method is often diverged in radio navigation. In other to avoid divergence problem QCLS (Quadratic Correction Least Square) method using TDOA (Time Difference of Arrival) measurements is introduced, but the estimation error is somewhat large. This paper presents the modified QCLS method using weighted least square. Since the weighting matrix is influenced by the unknown user position, two-step approach is employed in the proposed method. The weighting matrix is estimated in the first step using least square, and then find user position is obtained using weighted least square. Simulation results show that the performance of the proposed method is superior to the conventional QCLS all over the workspace.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.3
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• pp.271-279
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• 2006

Acoustic Emission (AE) technology is an effective nondestructive testing for continuous monitoring of defect formation and failures in structural materials. This paper presents a source location model using Acoustic Emission (AE) sensors in a Pre-Stressed Concrete (PSC) beam and the evaluation of the model was performed through lab experiments. 54 AE events were made on the surface of the 5m-PSC beam using a Schmidt Hammer and arrival times were measured with 7AE sensors. The source location f3r each event was estimated using least squares. The results were compared with actual positions and the RMSE (Root Mean Square Errors) was about 2cm.