• Title/Summary/Keyword: Real-Time Correction

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Correction of the Refraction Effect on the Real-Time Nonlinear Parameter Tomogram (초음파 비선형 단층영상에 나타나는 굴절의 영향 보정법)

  • 이현주;이강호;최종호;최종수
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.28B no.5
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    • pp.335-342
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    • 1991
  • A real-tme nonlinear parameter tomography is pumping wave method. This tomorgraphy has a merit which requires no 180$^{\circ}$ projection datum, while the ray-bending effect is remrkably remained on the reconstructed image. In this paper we intend to compensate this ray-bending effect using the perturbation method. Impulsive pumping wave makes derived compensative term simple form, nad the compensative image is easily obtained. We perform computer simulation to confirm the improvement of corrected imate.

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Accuracy Analysis of Code-based PPP-RTK Positioning Utilizing K-SSR Correction Messages Outside the Reference Network

  • Yoon, Woong-Jun;Park, Kwan-Dong;Kim, Hye-In;Woo., Seung;Park, Junpyo
    • Journal of Positioning, Navigation, and Timing
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    • v.6 no.2
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    • pp.79-86
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    • 2017
  • Precise Point Positioning-Real Time Kinematic (PPP-RTK) refers to a technology that combines PPP with network-RTK in which a user does not directly receive observed data from a reference station but receives State-Space Representation (SSR) messages corrected for error components from a central processing station through Networked Transport of RTCM via Internet Protocol (NTRIP) or Digital Multimedia Broadcasting (DMB) for purposes of positioning. SSR messages, which refer to corrections used in PPP-RTK, are generated by a central processing station using real-time observed data collected from reference stations and account for corrections needed due to the ionosphere, troposphere, satellite orbital errors, satellite time offsets, and satellite biases. This study used a type of SSR message provided in South Korea, known as Korea-SSR (K-SSR), to implement a PPP-RTK algorithm based on code-pseudorange measurements and validated its accuracy within the reference station network. In order to validate the accuracy of the implemented algorithm outside of the network, the K-SSR was extrapolated and applied to positioning in reference stations in Changchun, China (CHAN) and Japan (AIRA). This also entailed a quantitative evaluation that measured improvements in accuracy in comparison with point positioning. The results of the study showed that positioning applied with extrapolated K-SSR correction data was more accurate in both AIRA and CHAN than point positioning with improvements of approximately 20~50%.

A Study on the Impact of Real Exchange Rate Volatility of RMB on China's Foreign Direct Investment to Japan

  • He, Yugang
    • East Asian Journal of Business Economics (EAJBE)
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    • v.6 no.3
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    • pp.24-36
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    • 2018
  • Purpose - From establishing China-Japan diplomatic relations in 1972, the relations between two states has improved a lot, from which makes the government and the people reap much benefit. Owing to this reason, this paper aims at exploiting the impact of exchange rate volatility of RMB on China's foreign direct investment to Japan. Research design and methodology - The quarterly time series data from 2003 to 2016 will be employed to conduct an empirical analysis under the vector error correction model. Meanwhile, a menu of estimated methods such the Johansen co-integration test and the Granger Causality test will be also used to explore the impact of exchange rate volatility of RMB on China's foreign direct investment to Japan. Results - The empirical analysis results exhibit that the real exchange rate has a positive effect on China's foreign direct investment to Japan in the long run. Conversely, the real exchange rate volatility of RMB, the trade openness and the real GDP have a negative effect on China's foreign direct investment to Japan in the long run. However, in the short run, the China's foreign direct investment to Japan, the real exchange rate, the trade openness and the real GDP in period have a negative effect on China's foreign direct investment to Japan in period. Oppositely, the real exchange rate volatility of RMB in period has a positive effect on China's foreign direct investment to Japan in period. Conclusions - From the empirical evidences in this paper provided, it can be concluded that an increase in the exchange rate volatility of RMB can result in a decrease in the China's foreign direct investment to Japan in the long run. However, an increase in the exchange rate volatility of RMB can lead to an increase in the China's foreign direct investment to Japan in the short run. Therefore, the China's government should have a best control of the real exchange rate volatility of RMB so as to improve China's foreign direct investment to Japan.

Development and Performance Analysis of a Near Real-Time Sensor Model Correction System for Frame Motion Imagery (프레임동영상의 근실시간 센서모델 보정시스템 개발 및 성능분석)

  • Kwon, Hyuk Tae;Koh, Jin-Woo;Kim, Sanghee;Park, Se Hyoung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.3
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    • pp.315-322
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    • 2018
  • Due to the increasing demand for more rapid, precise and accurate geolocation of the targets on video frames from UAVs, an efficient and timely method for correcting sensor models of motion imagery is required. In this paper, we propose a method to adjust or correct sensor models of motion imagery frames using space resection via image matching with reference data. The proposed method adopts image matching between the motion imagery frames and the reference frames which are synthesized from reference data. Ground or reference control points are generated or selected through the matching process in near real time, and are used for space resection to get adjusted sensor models. Finally, more precise and accurate geolocation of the targets can possibly be done on the fly, and we have got the promising result on performance analysis in terms of the geolocation quality.

Study on the Real-Time Precise Orbit Biases Correction Technique for the GPS/VRS Network

  • Li, Cheng-Gang;Huang, Ding-Fa;Zhou, Dong-Wei;Zhou, Le-Tao;Xiong, Yong-Liang;Xu, Rui
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.2
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    • pp.251-254
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    • 2006
  • A precise real-time method of using the IGS ultra rapid products (IGU) and the GPS broadcast ephemeris to calculate the VRS orbit corrections was presented here which was suited for GPS/VRS reference station network based positioning. Test data acquired from both the SGRSN (Sichuan GPS Reference Station Network) and SCIGN (Southern California integrated GPS network) were used to evaluate the performance of the modeling techniques. The new method was proven to be more precise and reliable compared with the existing conventional network-based orbit error interpolation method. It was shown that 0.004ppm relative accuracy was reached, namely the influence from the orbit bias for the RTK positioning within 100km area can be of sub-millimeter level.

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Automatic Jitter Evaluation Method from Video using Optical Flow (Optical Flow를 사용한 동영상의 흔들림 자동 평가 방법)

  • Baek, Sang Hyune;Hwang, WonJun
    • Journal of Korea Multimedia Society
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    • v.20 no.8
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    • pp.1236-1247
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    • 2017
  • In this paper, we propose a method for evaluating the uncomfortable shaking in the video. When you shoot a video using a handheld device, such as a smartphone, most of the video contains unwanted shake. Most of these fluctuations are caused by hand tremors that occurred during shooting, and many methods for correcting them automatically have been proposed. It is necessary to evaluate the shake correction performance in order to compare the proposed shake correction methods. However, since there is no standardized performance evaluation method, a correction performance evaluation method is proposed for each shake correction method. Therefore, it is difficult to make objective comparison of shake correction method. In this paper, we propose a method for objectively evaluating video shake. Automatically analyze the video to find out how much tremors are included in the video and how much the tremors are concentrated at a specific time. In order to measure the shaking index, we proposed jitter modeling. We applied the algorithm implemented by Optical Flow to the real video to automatically measure shaking frequency. Finally, we analyzed how the shaking indices appeared after applying three different image stabilization methods to nine sample videos.

Real time GPS position correction using a camera and the vanishing point when a vehicle runs (카메라와 무한원점을 이용한 주행중 실시간 GPS 위치 보정)

  • Kim, Bo-Sung;Jeong, Jun-Ik;Rho, Do-Whan
    • Proceedings of the KIEE Conference
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    • 2004.11c
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    • pp.508-510
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    • 2004
  • In this paper, we proposed the GPS position data correction method for autonomous land navigation using vanishing point property and a monocular vision system. Simulations are carried out over driving distances of approximately 60 km on the basis of realistic road data. In straight road, the proposed method reduces GPS position error to minimum more than 63% and positioning errors within less than 0.5m are observed. However, the average accuracy of the method is not presented. because it is difficult to estimate it in curve road or other road environments.

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Real time GPS position data correction using the vanishing point and a monocular vision system for autonomous land navigation (무한원점과 단일 비젼 시스템을 이용한 자율주행을 위한 실시간 GPS 위치 데이터 보정)

  • 정준익;노도환
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.41 no.6
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    • pp.187-193
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    • 2004
  • In this paper, we proposed the GPS position data correction method for autonomous land navigation using vanishing point property and a monocular vision system. Simulations are carried out over driving distances of approximately 60 km on the basis of realistic road data. On a straight road, the proposed method reduces GPS position error by at least 63% within 0.5 m. However, the average accuracy of the method is not presented, because it is difficult to estimate it on other than a straight road in variable conditions.

A Study on Accuracy Analysis of DGPS-Based Marine Radiobeacon in the East Coast of Korea (한국동해안에서의 Marine Radiobeacon/DGPS 정밀도 분석에 관한 연구)

  • 고광섭;이형욱;정세모
    • Journal of the Korean Institute of Navigation
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    • v.22 no.1
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    • pp.1-13
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    • 1998
  • Radiobeacons that carry corrections for global satellite navigation systems are currently being planned or installed in many countries. In early 1996, it was begun to send DGPS correction message from a marine radiobeacon station located in Changgi Got Lighthouse. It was the first test broadcast of DGPS correction data based on medium frequency of marine radiobeacon where transmission power and rate are 300W and 100bps respectively in Korea. However, there has not been any scientific study on the characteristic of the accuracy of a marine radiobeacon/DGPS. Accordingly, this paper investigates the accuracy of the system, which is currently operating in 310kHz. To do this , the real time differential correction in RTCM data was collected in an implemented system. And then the accuracy was analyzed related to the coverge of the radiobeacon/DGPS. As a result, it is verified that the differential positioning accuracy using the marine radiobeacon is sufficient to ensure the safety of marine activities around the coast of Korea.

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Development of real-time program correcting error in radar polarimetric variables (실시간 레이더 편파변수 오차 보정 프로그램 개발)

  • Yoon, Jungsoo;Hwang, Seok-Hwan;Kang, Narae;Lee, Dong-Ryul;Lee, Keon-Haeng
    • Journal of Korea Water Resources Association
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    • v.54 no.12
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    • pp.1329-1338
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    • 2021
  • Rain radar provides high spatio-temporal radar rainfall that can be used as input data to short-term precipitation forecasting models. Korea Institute of Civil Engineering and Building Technology (KICT) has developed a flash flood forecasting system that is providing flash flood forecasting based on short-term rainfall forecasts estimated by the radar rainfall. Accuracy of the radar rainfall as well as the short-term rainfall forecasts, however, can deteriorate when radar polarimetric variables have error. In this study, we develope real-time program that can correct the error inherent in the radar polarimetric variables. First, effect according to the correction of the error was verified using 363 rainfall events on non real-time. The accuracy (1-NE) of the radar rainfall was approximately 70% and correlation coefficient was higher than 0.8 after correcting the error on non real-time. The accuracy (1-NE) using the real-time program was also approximately 70% after correcting the error.