• Journal of Korea Water Resources Association
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• v.56 no.8
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• pp.509-520
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• 2023

Various drought indices are widely used for assessing drought conditions which are affected by many factors such as precipitation, soil moisture, and runoff. The values of drought indices varies depending on hydro-meteorological data and calculation formulas, and the judgment of the drought condition may also vary. This study selected four calculation components such as precipitation data length, accumulation period, probability distribution function, and parameter estimation method as the sources of uncertainty in the calculation of standardized precipitation index (SPI), and evaluated their contributions to the uncertainty using root mean square error (RMSE) and linear mixed model (LMM). The RMSE estimated the overall errors in the SPI calculation, and the LMM was used to quantify the uncertainty contribution of each factor. The results showed that as the accumulation period increased and the data period extended, the RMSEs decreased. The comparison of relative uncertainty using LMM indicated that the sample size had the greatest impact on the SPI calculation. In addition, as sample size increased, the relative uncertainty related to the sample size used for SPI calculation decreased and the relative uncertainty associated with accumulation period and parameter estimation increased. In conclusion, to reduce the uncertainty in the SPI calculation, it is essential to collect long-term data first, followed by the appropriate selection of probability distribution models and parameter estimation methods that represent well the data characteristics.

• Journal of the Korean Geotechnical Society
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• v.27 no.8
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• pp.63-71
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• 2011

In case of applying BIM method to the civil engineering of irregularly shaped structure, BIM method is recognized to have relatively high construction productivity. In this paper, we developed quantity calculation algorithms applying BIM method to NATM tunnel construction method and implemented BIM based 3D-BIM Modeling Quantity Calculation. The results showed that BIM-based method has high reliabilty in structure work in which errors occurred only in the range between 0.00% and -1.45%. On the other hand, BIM method applied to earth work showed great error range of -19.78% to 35.30%. So the benefit and applicability of BIM method in civil engineering were confirmed. In addition, routine method for the quantity of earth work has negligible error as in the case of structure work. But, rock type's quantity calculation showed significant errors so that the reliability of 2D-based volume calculation is problematic. It may thus be concluded that 3D-BIM is more reliable than the routine method in estimating the quantity of earth work. Considering the reliability and merits in the stage of its design, construction and maintenance levels, the application of BIM to civil engineering works is recommended.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.938-941
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• 1999

In this paper, we designed a pipeline (15,9) Reed-solomon decoder. To compute the error locator polynomials, we used the Euclidean algorithm. This algorithm includes computation of inverse element. We avoided the inverse element calculation in this RS decoder by using ROMs. We designed this decoder using VHDL. Simulation results show that the designed decoder corrects three error symbols. We implemented this design through an Altera FPGA chip.

• Journal of radiological science and technology
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• v.30 no.1
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• pp.33-38
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• 2007

The propose of this study is a verification of the correct calculation of the dose around source and the prescription dose of Ir-192 source in the plato treatment planning system. The source and orthogonal coordinates for lateral direction and those for the anterior posterior direction were drawn on a A4 paper and then input into the system. The prescription dose was prescribed to two points with radius 1 cm in the direction of polar angle $90^{\circ} and $270^{\circ} from the center of the source. The doses of prescription point and dose points acquired from the treatment planning system were compared with those from manual calculation using the geometry function formalism derived by Paul King et al. In this analysis, the doses of prescription point were exactly consistent with each other and those of dose points were obtained within the error point of 1.85%. And the system of accuracy was evaluated within 2% of tolerance error. Therefore, this manual dose calculation used for the geometry function formalism is considered to be useful in clinics due to its convenience and high quality assurance.

• Nuclear Engineering and Technology
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• v.16 no.4
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• pp.202-216
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• 1984

The success of coarse-mesh nodal solution methods provides strong motivation for finding homogenized parameters which, when used in global nodal calculation, will reproduce exactly all average nodal reaction rates for large nodes. Two approximate theories for finding these ideal parameters, namely, simplified equivalence theory and approximate node equivalence theory, are described herein and then applied to the PWR benchmark problem. Nodal code, ANM, is used for the global calculation as well as for the homogenization calculation. From the comparative analysis, it is recommended that homogenization be carried out only for the unique type of fuel assemblies and for core boundary color-sets. The use of approximate homogenized cross-sections and approximate discontinuity factors predicts nodal powers with maximum error of 0.8% and criticality within 0.1% error relative to the fine-mesh KIDD calculations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.205-213
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• 2009

This study was planned to develop monitoring system of cable force to resolve cable force of cable-stayed bridge efficiently in a long-term plan. In the proposed monitoring system, firstly data are sampled from real-time acceleration record, secondly these sampled data are frequency analyzed by using the FFT(Fast Fourier Transform) algorism and lastly the analyzed results are averaged and generalized. For evaluating the applicability of this monitoring system, field loading test has performed in real cable-stayed bridge. In comparison with cable force by field manual calculation and cable force of monitoring system by semi-automatic calculation, the difference of calculated cable forces has within 1% error range and it is acceptable range. Additionally within negligible 5% error range of difference has occur between field manual calculation and monitoring system by automatic calculation. so monitoring system in this study has been verified to be reliable.

• KIEAE Journal
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• v.14 no.4
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• pp.35-45
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• 2014

The main objective of this study is to provide an effective algorithm of the transmitted solar radiation calculation through window glazing on a clear day. This algorithm would be used in developing a computer program for fenestration system analysis and shading device design. Various simulation methods have been evaluated to figure out the most accurate and effective procedure in estimation of transmitted solar radiation on a tilted surface on a clear day. Characteristics of simulated results of each step have been scrutinized by comparing them with measured results of the site as well as results from other simulation programs. Generally, the Duffie & Beckman's solar calculation method introducing the HDKR anisotropic model provided the most reliable simulation results. The DOE-2 program usually provided over-estimated simulation results. The estimation of extraterrestrial solar radiation and beam normal radiation were conducted pretty accurately. However, the solar radiation either on horizontal surface or on tilted surface involves complicated factors in estimation. Even though the estimation results were close to the real measured data during summer when solar intensity is getting higher, the estimation provided more error when solar intensities were getting weaker. The convex polygon clipping algorithm with homogeneous coordinates was fastest model in calculation of sunlight to shaded area ratio. It could not be applied because of its shape limitation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1667-1675
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• 2003

This paper has considered the calculation of lateral stiffness of radial tire's sidewall, which consists of cord stiffness and rubber sheet stiffness, by using the material constants of rubber compounds of tire. We have suggested and illustrated how to calculate the rubber sheet lateral stiffness by considering the following aspects. First, the rubber sheet consists of various kinds of rubber compounds with different thickness along the sidewall in the radial direction. Secondly, equivalent Young's modulus of the rubber sheet can be calculated by using available experimental data of rubber compounds. The present method enables us to divide the calculation domain as many as we want, which can reduce numerical error in the calculation of geometrical and mechanical properties. We have illustrated the calculation by using the data of the radial tire for passenger car of P205/60R15.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.129-137
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• 1984

In brachytherapy, it is important to determine the positions of the radiation sources which are inserted into a patient and to estimate the dose resulting from the treatment. Calculation of the dose distribution throughout an implant is so laborious that it is rarely done by manual methods except for model cases. It is possible to calculate isodose distributions and tumor doses for individual patients by the use of a microcomputer. In this program, the dose rate and dose distributions are calculated by numerical integration of point source and the localization of radiation sources are obtained from two radiographs at right angles taken by a simulator developed for the treatment planning. By using microcomputer for brachytherapy, we obtained the result as following 1. Dose calculation and irradiation time for tumor could be calculated under one or five seconds after input data. 2. It was same value under$\pm2\%$ error between dose calculation by computer program and measurement dose. 3. It took about five minutes to reconstruct completely dose distribution for intracavitary irradiation. 4. Calculating by computer made remarkly reduction of dose errors compared with Quimby's calculation in interstitial radiation implantation. 5. It could calculate the biological isoffect dose for high and low dose rate activities.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1479-1486
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• 2019

The purpose of the present study is to develop the 3D static and noise simulator based on Galerkin Finite Element Method (GFEM) using the unstructured hexahedral elements. The 3D, 2G neutron diffusion and noise equations are discretized using the unstructured hexahedral by considering the linear approximation of the shape function in each element. The validation of the static calculation is performed via comparison between calculated results and reported data for the VVER-1000 benchmark problem. A sensitivity analysis of the calculation to the element type (unstructured hexahedral or tetrahedron elements) is done. Finally, the neutron noise calculation is performed for the neutron noise source of type of variable strength using the Green function technique. It is shown that the error reduction in the static calculation is considerable when the unstructured tetrahedron elements are replaced with the hexahedral ones. Since the neutron flux distribution and neutron multiplication factor are appeared in the neutron noise equation, the more accurate calculation of these parameters leads to obtaining the neutron noise distribution with high accuracy. The investigation of the changes of the neutron noise distribution in axial direction of the reactor core shows that the 3D neutron noise analysis is required instead of 2D.