• Journal of Cadastre & Land InformatiX
• /
• v.48 no.2
• /
• pp.99-108
• /
• 2018

The purpose of this study is to determine the precise height in mountainous areas of South Korea and Jiri mountain area was selected as a test bed for the study. Gravity observation and GNSS surveying were performed for 44 BM(Benchmark) points in the test bed and calculate the height and the height correction. In the calculation, the dynamic correction amount, the orthometric correction amount and the normal correction amount were calculated, and the dynamic height and orthometric height and the normal height were calculated considering each correction amount. The results showed that the difference between normal gravity and observed gravity and also the difference between orthometric correction and the normal correction. In addition, the results of the comparison of the present official BM height and the computed orthometric height in this study show that Korean height system should be shifted from the normal orthometric height system to the orthometric height system. Because the difference between the orthometric correction and the normal correction within the test bed indicated a distribution of at a minimum of -234.41 mm up to 196.925 mm, and the difference between the present official BM height and the calculated orthometric height were distributed from -0.121m to 0.011 m.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.249-254
• /
• 1987

This paper presents a new method for generating smooth free-form surface by local correction. B-spline surface is used for its convenience of local correction, and the direction of surface correction is fixed to the average-surface-normal direction. The surface to be corrected is approximated into a uniform cubic B-spline surface. Then, the smoothness (curvature arrows, iso-parametric lines) of the approximated surface is displayed with B-spline control points. When a control point near the region that needs correction is selected, a new point 1 mm higher than the original control point in the direction of the average surface normal is displayed. And the surface is corrected by giving the amount of control point movement interactively. Since the direction of correction is given by the program and the amount of correction is selected by the user, the method is called semiautomatic. sufficiently smooth surface can be obtained by this method. Examples are given to illustrate the method.

• Geophysics and Geophysical Exploration
• /
• v.20 no.4
• /
• pp.232-240
• /
• 2017

Normal moveout correction is one of the main procedures of seismic reflection data processing and a crucial pre-processing step for AVO analysis. Unfortunately, stretch phenomenon, which is the intrinsic problem of NMO correction, degrades the quality of stack section and reliability of AVO analysis. Although muting is applied to resolve this problem, it makes far-offset traces more useful to develop an advanced NMO correction technique without stretch. In this paper, easy and detailed explanations are provided on the definition and methodology of NMO correction, and then the cause of stretch is explained with its characteristics. A graphical explanation for NMO correction is given for the intuitive understanding of stretch phenomenon. Additionally, the theoretical formulation is derived to quantitatively understand the NMO correction. Through explaining the muting process to remove NMO stretch, the limitations of conventional methods are investigated and the need for a new resolution comes to discussion. We describe a stretch-free NMO correction based on inverse theory among many different stretch-free NMO corrections. Finally, the stretch-free NMO correction is verified through synthetic example and real data.

• Journal of Korea Multimedia Society
• /
• v.18 no.2
• /
• pp.106-112
• /
• 2015

In this paper, we propose a method for correction of perspective distortion on a taken image. An image taken by a camera is caused perspective distortion depending on the direction of the camera when objects are projected onto the image. The proposed method in this paper is to obtain the normal vector of the plane through the depth information using a depth camera and calculate the direction of the camera based on this normal vector. Then the method corrects the perspective distortion to the view taken from the front side by performing a rotation transformation on the image according to the direction of the camera. Through the proposed method, it is possible to increase the processing speed than the conventional method such as correction of perspective distortion based on color information.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.1
• /
• pp.79-85
• /
• 2014

Purpose: This study investigated accommodative changes by measuring accommodative response, appearing on the normal and convergence insufficiency Group, by using both eyes open-view auto-refractometer (Nvision-K5001, shin-nippon, Japan). Methods: It carried out objective and subjective refractions, targeting 74 college students (54 males and 20 females) aged between 19 and 29 ($21.59{\pm}2.53$), spherical equivalent OD $-2.28{\pm}2.03$ D, OS $-2.18{\pm}2.01$ D, by measuring accommodative responses at full correction and under correction with plus lens +0.25, +0.50, +0.75 arbitrarily added. Results: In the group of normal and convergence insufficiency, the shorter fixation distances were, the greater accommodative lags showed. The group of convergence insufficiency showed the lesser changes of accommodative response than those of normal. But we found that the convergence insufficiency group had a little larger accommodative amplitude in the total fixation distances. The full correction of convergence insufficiency group and the under correction (+0.50 D) of normal were alike in the accommodative responses. We have also investigated that the correlation between accommodative responses and fixation distances was decreased steeply at the excessive low vision correction. Conclusions: Under correction (+0.50 D) in a near distance is expected to avoid unnecessary accommodative responses, make eyes relaxed and comfortable.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.29 no.3
• /
• pp.319-325
• /
• 2011

It has been used not orthometric height but normal orthometric height for the official height in Korean benchmark because it has been used not observed gravity but normal gravity for the computation of orthometric correction. The purpose of this study is to propose height renewal method of Korean benchmark. For this purpose, we observed gravity by CG5 digital gravimeter in both the first benchmark line between Sokcho and Gangneung area and the second benchmark line between Soksa and Inje area. We calculated relative gravity value and orthometric correction in all benchmarks. So, the maximum orthometric correction shows -0.349mm in the first benchmark line, and the maximum orthometric correction shows -44.060mm in the second benchmark line. In conclusion, we can confirm that the orthometric correction based on observed gravity is necessary for more accurate official height computation in the Korean benchmark.

• The Journal of Korean Physical Therapy
• /
• v.24 no.2
• /
• pp.66-72
• /
• 2012

Purpose: The purpose of this study is to explore the importance of the image distortion correction in the cross sectional area measurement for the iliopsas muscle, tensor fasciae latae muscle, gluteus maximus muscle and the knee extensor muscles, by using (magnetic resonance imaging) MRI. Methods: This study was performed using an open 0.32T MRI system. To estimate the image distortion, T1 images for an AAPM homogeneity/linearity phantom were acquired, and the region in which the maximum geometric distortion was less than or equal to the pixel size (1.6 mm) of the images, it was defined as the distortion correction-free region. The T2 images for a human subject's pelvis and thigh in normal positions were obtained. Then, after the regions of interest in the pelvis and thigh were moved into the distortion correction-free region, T2 images for the pelvis and thigh were scanned with the same imaging parameters used in the previous T2 imaging. The cross-sectional areas were measured in the two T2 images that were obtained in the normal position, and the distortion correction-free region, as well as the area error caused by geometric image distortion was calculated. Results: The geometrical distortion is gradually increased, from the magnet center to the outer region, in axial and coronal plane. The cross-sectional area error of gluteus maximus muscle and the knee extensors was as high as 9.27% and 3.16% in before and after distortion correction, respectively. Conclusion: The cross-sectional area of the muscles that suffered from the geometrical distortion is necessary to correct for the estimation of the intervention.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.42
• /
• pp.19.1-19.4
• /
• 2020

Background: The tongue in groove technique (TIG) is a useful technique for the correction of the nasal tip projection and the nasolabial angle. The purpose of this study was to determine the utility of this technique for nasal tip rotation and projection correction in the Iranian society. Methods: This is a retrospective clinical trial study of 20 patients undergoing open septo-rhinoplasty using TIG technique from January 2017 to August 2019 at the oral and maxillofacial unit of Bu Ali Hospital and private sector. Preoperative and postoperative profile view photographs were compared to assess the changes in tip projection and rotation. Results: Fifteen patients (75%) had normal angular size, and 5 of them (25%) were not within the normal range after the surgery. The Fisher exact test showed that this success was statistically significant (P = 0.006). Ten patients (50%) had normal projection size, postoperatively. The Fisher exact test showed that this effect was statistically significant (P < 0.01) Conclusion: The study demonstrated the benefit of TIG on the correction of nasal tip projection and rotation.

• Journal of the Korean Statistical Society
• /
• v.34 no.4
• /
• pp.345-366
• /
• 2005

This paper considers the cointegrating vector estimator in the error correction model with stationary covariates, which combines the stationary vector autoregressive model and the nonstationary error correction model. The cointegrating vector estimator is shown to follow the locally asymptotically mixed normal distribution. The variance of the estimator depends on the co­variate effect of stationary regressors, and the asymptotic efficiency improves as the magnitude of the covariate effect increases. An economic application of the money demand equation is provided.

• Proceedings of the KSRS Conference
• /
• 1998.09a
• /
• pp.252-256
• /
• 1998

Accurate mapping of satellite images is one of the most important Parts in many remote sensing applications. Since the position and the attitude of a satellite during image acquisition cannot be determined accurately enough, it is normal to have several hundred meters' ground-mapping errors in the systematically corrected images. The users which require a pixel-level or a sub-pixel level mapping accuracy for high-resolution satellite images must use a number of Ground Control Points (GCPs). In this paper, the performance of two geometric correction algorithms is tested and compared. One is the polynomial warping algorithm which is simple and popular enough to be implemented in most of the commercial satellite image processing software. The other is full camera modelling algorithm using Physical orbit-sensor-Earth geometry which is used in satellite image data receiving, pre-processing and distribution stations. Several criteria were considered for the performance analysis : ultimate correction accuracy, GCP representatibility, number of GCPs required, convergence speed, sensitiveness to inaccurate GCPs, usefulness of the correction results. This paper focuses on the usefulness of the precision correction algorithm for regular image pre-processing operations. This means that not only final correction accuracy but also the number of GCPs and their spatial distribution required for an image correction are important factors. Both correction algorithms were implemented and will be used for the precision correction of KITSAT-3 images.