• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.226-235
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• 2000

Two representative finite volume methods, i.e., the time marching method and the pressure correction method, were applied to 8 centrifugal compressor impeller flows, with low to very high level of pressure ratio, among which 7 impellers' experimental performance is given in the open literature. The present study is focused on the prediction differences from both methods, developed by the authors, in the pressure correction method's point of view. In all cases, the time marching method gives a satifactory solution, but the pressure correction method does not. Up to about $18\%$ less level of total-to-total pressure ratio is predicted by the pressure correction method as the level of the impeller pressure ratio increases up to about 10. The drop of total pressure ratio is caused by the underestimation of static pressure rise which seems to be attributed to inappropriate linearization and discretization of the pressure/density coupling terms in the pressure correction equation.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.2
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• pp.112-117
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• 2008

Artifact corrections including normalization and attenuation correction were important for quantitative analysis in Nuclear Medicine Imaging. Normalization is the process of ensuring that all lines of response joining detectors in coincidence have the same effective sensitivity. Failure to account for variations in LOR sensitivity leads to bias and high-frequency artifacts in the reconstructed images. Attenuation correction is the process of the correction of attenuation phenomenon lies in the natural property that photons emitted by the radiopharmaceutical will interact with tissue and other materials as they pass through the body. In this paper, we will review the several approaches for normalization and attenuation correction strategies.

• East Asian mathematical journal
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• v.36 no.4
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• pp.437-454
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• 2020

The purpose of this study is to develop a mathematical assessment and correction materials according to the mathematics learning hierarchy. The scope of the study is set to 'function' in 7th grade of middle school. The researchers developed a draft of the mathematical assessment and correction materials based on the mathematics learning hierarchy through the pilot test and the expert review. Using the results of the expert review, the researchers modified and supplemented the math assessment and correction materials to produce the final version. The mathematics assessment and correction material developed in this study is expected to build an effective guidance system for students with mathematics deficits. In addition, by presenting a mathematical assessment and correction materials to the teachers in the field, it is possible to reduce the effort for the management of underachievers and to provide guidance for the education of students with a lack of math learning.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.3
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• pp.74-81
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• 2014

The coverage area of GNSS regional ionospheric correction model is mainly determined by the disribution of GNSS ground monitoring stations. Outside the coverage area, GNSS users may receive ionospheric correction signals but the correction does not contain valid correction information. Extrapolation of the correction information can extend the coverage area to some extent. Three interpolation methods, Kriging, biharmonic spline and cubic spline, are tested to evaluate the extrapolation accuracy of the ionospheric delay corrections outside the correction coverage area. IGS (International GNSS Service) ionosphere map data is used to simulate the corrections and to compute the extrapolation error statistics. Among the three methods, biharmonic method yields the best accuracy. The estimation error has a high value during Spring and Fall. The error has a high value in South and East sides and has a low value in North side.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.10
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• pp.1559-1562
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• 2022

As electronic devices technology scales down into the deep-submicron to achieve high-density, low power and high performance integrated circuits, multiple bit upsets by soft errors have become a major threat to on-chip memory systems. To address the soft error problem, single error correction, double error detection and double adjacent error correction (SEC-DED-DAEC) codes have been recently proposed. But these codes do not troubleshoot mis-correction problem. We propose the SEC-DED_DAEC code with without mis-correction. The decoder for proposed code is implemented as hardware and verified. The results show that there is no mis-correction in the proposed codes and the decoder can be employed on-chip memory system.

• Journal of the Korea Institute of Building Construction
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• v.8 no.2
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• pp.107-112
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• 2008

According to Korean Architectural Standard Specification (KASS) , at the design stage of the specified concrete strength, strength correction with each temperature level should be considered to secure required strength at 28 days even in low temperature condition, In this paper, the period for the strength correction at the stage of mixture design of the concrete using ordinary Portland cement(OPC) specified in KASS was determined with each region of south Korea based on the meteorological data of KMA(Korea meteorological administration) by applying KASS-5 regulation. In case of 28 days of strength control age, the period for strength correction with 6MPa was calculated to $50{\sim}60$ days and, with 3 MPa. to around 80 days. The period for the strength correction was shown to be decreased with the rise of altitude. The period to consider the delay of the strength development due to low temperature including the period of cold weather concrete was nearly 7 months around 1 year. References for determining the strength correction factors with each region of south Korea was provided in this paper. Further investigation of strength correction of the concrete containing blended cement is to studied.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.221-224
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• 2006

seismic crosshole tomography works applying borehole deviation correction were performed at a test site to detect a small cavity. Two correction methods were applied. The one is the constant distance correction which adds constant distance to surface borehole distance and the other is the constant angle correction which considers an angle between surface borehole location and bottom borehole location. After applying the corrections, the distortions of the image diminished while its resolution improved. Though the constant angle correction is the most appropriate correction method, the constant distance correction can delineate the small cavity sufficiently.

• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.127-139
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• 2018

The GOCI atmospheric correction overland surfaces is essential for the time-series analysis of terrestrial environments with the very high temporal resolution. We develop an operational GOCI atmospheric correction method over land surfaces, which is rather different from the one developed for ocean surface. The GOCI atmospheric correction method basically reduces gases absorption and Rayleigh and aerosol scatterings and to derive surface reflectance from at-sensor radiance. We use the 6S radiative transfer model that requires several input parameters to calculate surface reflectance. In the sensitivity analysis, aerosol optical thickness was the most influential element among other input parameters including atmospheric model, terrain elevation, and aerosol type. To account for the highly variable nature of aerosol within the GOCI target area in northeast Asia, we generate the spatio-temporal aerosol maps using AERONET data for the aerosol correction. For a fast processing, the GOCI atmospheric correction method uses the pre-calculated look up table that directly converts at-sensor radiance to surface reflectance. The atmospheric correction method was validated by comparing with in-situ spectral measurements and MODIS reflectance products. The GOCI surface reflectance showed very similar magnitude and temporal patterns with the in-situ measurements and the MODIS reflectance. The GOCI surface reflectance was slightly higher than the in-situ measurement and MODIS reflectance by 0.01 to 0.06, which might be due to the different viewing angles. Anisotropic effect in the GOCI hourly reflectance needs to be further normalized during the following cloud-free compositing.

• KIISE Transactions on Computing Practices
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• v.23 no.7
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• pp.446-451
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• 2017

The statistical context-sensitive spelling correction technique in this thesis is based upon Shannon's noisy channel model. The interpolation method is used for the improvement of the correction method proposed in the paper, and the general interpolation method is to fill the middle value of the probability by (N-1)-gram and (N-2)-gram. This method is based upon the same statistical corpus. In the proposed method, interpolation is performed using the frequency information between the statistical corpus and the correction document. The advantages of using frequency of correction documents are twofold. First, the probability of the coined word existing only in the correction document can be obtained. Second, even if there are two correction candidates with ambiguous probability values, the ambiguity is solved by correcting them by referring to the correction document. The method proposed in this thesis showed better precision and recall than the existing correction model.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.89-98
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• 2011

Four kinds of gain and offset correction coefficients that are used to correct the nonuniformity between pixels are discussed. And their correction performance has been compared by performing image correction. using the correction coefficients calculated, on the real image data obtained from a newly fabricated camera electronics system. The performance of the correction coefficients depends in general on the number of the light input levels used to obtain the reference image. The result shows that, as expected obviously, when only two light input levles are used to obtain the reference image, even though its correction coefficients are relatively easily calculated, the correction performance is relatively poor. And with the number of light inputs increased to a value of larger than two, the correction performance is improved. It is noted, however, no Significant performance difference is found between the different correction coefficients employed.