• Journal of Positioning, Navigation, and Timing
• /
• 제4권1호
• /
• pp.33-41
• /
• 2015

Compact Network Real-Time Kinematic (RTK) is a method that combines compact RTK and network RTK, and it can effectively reduce the time and spatial de-correlation errors. A network RTK user receives multiple correction information generated from reference stations that constitute a network, calculates correction information that is appropriate for one's own position through a proper combination method, and uses the information for the estimation of the position. This combination method is classified depending on the method for modeling the GPS error elements included in correction information, and the user position accuracy is affected by the accuracy of this modeling. Among the GPS error elements included in correction information, tropospheric delay is generally eliminated using a tropospheric model, and a combination method is then applied. In the case of a tropospheric model, the estimation accuracy varies depending on the meteorological condition, and thus eliminating the tropospheric delay of correction information using a tropospheric model is limited to a certain extent. In this study, correction information modeling accuracy performances were compared focusing on the Low-Order Surface Model (LSM), which models the GPS error elements included in correction information using a low-order surface, and a modified LSM method that considers tropospheric delay characteristics depending on altitude. Both of the two methods model GPS error elements in relation to altitude, but the second method reflects the characteristics of actual tropospheric delay depending on altitude. In this study, the final residual errors of user measurements were compared and analyzed using the correction information generated by the various methods mentioned above. For the performance comparison and analysis, various GPS actual measurement data were collected. The results indicated that the modified LSM method that considers actual tropospheric characteristics showed improved performance in terms of user measurement residual error and position domain residual error.

• Journal of the Optical Society of Korea
• /
• 제17권2호
• /
• pp.213-218
• /
• 2013

Although infrared focal plane array (IRFPA) detectors have been commonly used, non-uniformity correction (NUC) remains an important problem in the infrared imaging realm. Non-uniformity severely degrades image quality and affects radiometric accuracy in infrared imaging applications. Residual non-uniformity (RNU) significantly affects the detection range of infrared surveillance and reconnaissance systems. More effort should be exerted to improve IRFPA uniformity. A novel NUC method that considers the surrounding temperature variation compensation is proposed based on the binary nonlinear non-uniformity theory model. The implementing procedure is described in detail. This approach simultaneously corrects response nonlinearity and compensates for the influence of surrounding temperature shift. Both qualitative evaluation and quantitative test comparison are performed among several correction technologies. The experimental result shows that the residual non-uniformity, which is corrected by the proposed method, is steady at approximately 0.02 percentage points within the target temperature range of 283 K to 373 K. Real-time imaging shows that the proposed method improves image quality better than traditional techniques.

• 대한통합의학회지
• /
• 제3권3호
• /
• pp.89-94
• /
• 2015

Purpose : This study was analyzed to researched the improvement of the posture and breathing ability on correction method of posture and breathing exercise in Forward Head Posture(FHP) Method : Eighten forward head posture subjects participated in this study. The control group applied to correction method of posture and the experiment group applied to correction method of posture with breathing exercises. Results : The results showed significant improvement in Craniovertebra-Angle on each two group(P<0.05). All the other result showed non-significant in respiratory(Tidal volume, Expiratory residual volume, Inspiratory residual volume) But value of result is slightly improved in after exercise. Conclusion : CVA angle is increased in each group but not increased between experiment group and control group. Total Volume(TV), Inspiratory Reserve Volume(IRV) and Expiratory Reserve Volume(ERV) are a little increased.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집A
• /
• pp.412-418
• /
• 2001

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, eccentricity can usually occur between the hole center and rosette gage center. In this study, the error due to the hole eccentricity is corrected using the neural network. The neural network has trained training examples of normalized eccentricity, eccentric direction and direction of maximum stress at eccentric case using backpropagation learning process. The trained neural network could corrected the error of measured residual stress in experiments with hole eccentricity. The proposed neural network is very useful for correction of the error due to hole eccentricity in hole-drilling method.

• ETRI Journal
• /
• 제29권5호
• /
• pp.596-606
• /
• 2007

It is well known that an OFDM receiver is vulnerable to synchronization errors. Despite fine estimations used in the initial acquisition, there are still residual synchronization errors. Though these errors are very small, they severely degrade the bit error rate (BER) performance. In this paper, we propose a residual error elimination scheme for the digital OFDM baseband receiver aiming to improve the overall BER performance. Three improvements on existing schemes are made: a pilot-aided recursive algorithm for joint estimation of the residual carrier frequency and sampling time offsets; a delay-based timing error correction technique, which smoothly adjusts the incoming data stream without resampling disturbance; and a decision-directed channel gain update algorithm based on recursive least-squares criterion, which offers faster convergence and smaller error than the least-mean-squares algorithms. Simulation results show that the proposed scheme works well in the multipath channel, and its performance is close to that of an OFDM system with perfect synchronization parameters.

• Steel and Composite Structures
• /
• 제9권3호
• /
• pp.209-221
• /
• 2009

Heating correction, through heating and flattening a structure with a pressing machine, is the in-situ method used to repair buckled steel structures. The primary purpose of this investigation is to develop an FEM model which can predict the mechanical response of heat-corrected plates accurately. Our model clarifies several unsolved problems. In previous research, the location of the imperfection was limited to the center of the specimen although the mechanical behavior is strongly affected by the location of the imperfection. Our research clarifies the relationship between the location of the imperfection and the mechanical behavior. In addition, we propose further reinforcement methods and validate their effectiveness. Our research concludes that the strength of a buckled specimen can be recovered by heating correction and the use of an adequate stiffener.

• 한국항행학회논문지
• /
• 제26권6호
• /
• pp.412-417
• /
• 2022

본 논문에서는 MATLAB GUI 기반으로 개발된 다중 위성군 network RTK MAC 보정정보 생성 소프트웨어에 대해서 소개한다. 해당 소프트웨어는 GPS와 GLONASS, Galileo를 포함한 다중 위성군의 보정정보를 생성하는 알고리즘의 유효성을 평가하기 위해 시뮬레이션 데이터 기반 후처리 소프트웨어로 개발되었다. 소프트웨어 구동 결과 다중 위성군의 시스템별 network RTK 보정정보가 MATLAB 파일 형식으로 출력된다. 본 논문에서는 개발된 소프트웨어의 성능을 평가하기 위해 소프트웨어를 통해 생성된 보정정보를 사용자에게 적용한 후 잔여 오차를 분석하였다. 분석 결과 사용자 잔여 오차의 크기가 10 cm 이하를 유지하는 것을 확인함으로써, 유효한 network RTK 보정정보 생성이 가능함을 확인하였다.

• 한국자동차공학회논문집
• /
• 제9권6호
• /
• pp.201-206
• /
• 2001

The hole-drilling method makes a little hole through the metal surface that has residual stress and measures the relieved stress with a strain gage. It is used widely in measuring the residual stress of surfaces. In this method, the inclined hole is one of the source of error. This paper presents a finite element analysis of influence of the inclined hole for the uniaxial residual stress field. The stress differences between measured and applied residual stress increase proportionally to inclined angle of the hole. The correction equations which easily obtain the residual stress taking account of the inclined angle and direction are derived. The measurement error of stress due to the inclined hole can be reduced to around 1% through this study.

• Journal of Chest Surgery
• /
• 제33권2호
• /
• pp.139-145
• /
• 2000

Background: The purpose of this study is to review the clinical course after the correction of noncomplicated ventricular septal defect and to analyze the morbidity and risk factors of postoperative complications and evaluate residual defect during the follow-up period. Material and Method: From September 1994 to June 1998 24 patients(median age 10 months) underwent surgery under the diagnosis of ventricular septal defect. We made a retrospective review of the clinical records including the operation notes critical care unit records echocardiography results and the follow-up records. Result: There was no early mortality nd late mortality. There was no postoperative complete conduction block. Respiratory complication was the most common complication. The body weight age type of ventricular septal defect associated anomalies and operative procedure were not related to the incidence of complications. residual ventricular septal defects aortic valve regurgitation and tricuspid valve regurgitation were insignificant in postoperative hemodynamics, Conclusions: Correction of the noncomplicated ventricular septal defect was done without mortality and complete heart block. Aggressive preoperative medical treatment and early surgical treatment may decrease postoperative complications. Postoperative residual shunt and tricuspid regurgitation were not problematic during the follow-up

• 대한기계학회논문집A
• /
• 제24권8호
• /
• pp.2059-2064
• /
• 2000

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, one of the source of error is due to the misalignment between the drilling hole and strain gage center. This paper presents a finite element analysis of the influence of such misalignment for the uniaxial residual stress field. The stress error increases proportionally to hole eccentricity. The correction equations which easily obtain the residual stress taking account of the hole eccentricity are derived. The stress error due to the hole eccentricity decreases by approximately one percent using this equations.