• The Mathematical Education
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• v.46 no.2 s.117
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• pp.155-171
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• 2007

One second grader, Junsu, was observed 4 times before and after formal multiplication lesson in Grade 2. This study describes how solution strategies in multiplication problems develop over time and investigates awareness of the relation between situation and computation in simple measurement and partitive division problems as informally experienced. It was found that Junsu used additive calculation for small-number multiplication problems but could not solve large-number multiplication problems and that he did not have concept of mathematical terms at first interview stage. After formal teaching, Junsu learned a variety of multiplication solution strategies and transferred from additive calculation to multiplicative calculation. The cognitive processing load of each strategy was gradually reduced. Junsu experienced measurement division as a dealing strategy and partitive division as a estimate-adjust strategy dealing more than one object in the first round.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.16-23
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• 1992

Conductance calculation is essential in designing a vacuum system. Since mathematical solution is nearly impossible except for a few simple cases, it has been so usual to calculate the conductance for a series connection of components using an approximate formula by Oatley. However, Oatley's formula has a fundamental flaw of totally neglecting the effect of gas beaming. In this study, a new technique is suggested for calculating the conductance with the same accuracy as the Monte Carlo method but with much less computing time, and applied to a system of tube connections in series. The effects of gas beaming in the calculation of conductance is analyzed quantitatively by comparing the conductance calculated by this method with those from Oatley's formula.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1386-1391
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• 2008

As the time goes by, the energy use in buildings are increasing threateningly. So, it is important to have an accurate energy load calculation for buildings. The accurate energy simulation program carries numerous input data. So, our purpose of this study is to verify the application of simplify modeling method which eliminates coordinates of building components instead of using full coordinates by using DOE2. After comparing original modeling method with simplify modeling method, we applied PAF for daylighting control in the building to verify the application of daylighting control in simplify modeling method. The results shows that there are little difference between original modeling and simplify modeling. Also it showed that application of daylighting control has little difference between original modeling so it is feasible to adapt simplify modeling. These results reveals that the application of simplify modeling is possible to predict energy load and use of the building.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.1
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• pp.40-45
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• 1991

This paper proposes a simplifying model for the calculation of the radiant flux and radiation energy in an RD (Radiation Dominated) arcplasma. Defects of the previous models are that the radiant flux and radition energy must be numerically solved by the three dimensional integration, and these calculations demand enormous computing time. Thses attribute to the global properties of radiation transfer. This paper suggests a simple calculation technique of radiation characteristics by considerig the relation between the plasma states and the radiation transfer process and by the systematic tabulation of the relation.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.673-675
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• 2003

As the electrical power industry is restructured and the electrical power exchange is updated per hour, it is important to accurately and rapidly quantify ATC of the transmission system. This paper proposed QFA method, which can reduce calculation time comparing with CPF method and has few errors in ATC calculation. It proved that the method can calculate ATC more fast and accurately in case study using IEEE 24 bus RTS(MRTS) and 7 bus.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.55-57
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• 2009

This paper deals with an improved core loss calculation under the load conditions, namely, no-load, AC-load and DC-load of multi-pole PM generator from curve fitting method using modified Steinmetz equation considered anomalous loss. For an accurate calculation, magnetic field analyses in stator core considering the time harmonics are performed. And using the nonlinear finite element analysis (FEA), we applied separated rotating and alternating magnetic field to core loss calculation. In order to verify the core loss results by proposed method, the experimental system for no-load core loss measurement has been implemented with DC motor, power analyzer and manufactured PM generator. And, the analysis results with rotational speed agree extremely well with those obtained by measurement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.10
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• pp.3482-3497
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• 2021

Artificial intelligence has emerged as the core of the 4th industrial revolution, and large amounts of data processing, such as big data technology and rapid data analysis, are inevitable. The most fundamental and universal data interpretation technique is an analysis of information through regression, which is also the basis of machine learning. Ridge regression is a technique of regression that decreases sensitivity to unique or outlier information. The time-consuming calculation portion of the matrix computation, however, basically includes the introduction of an inverse matrix. As the size of the matrix expands, the matrix solution method becomes a major challenge. In this paper, a new algorithm is introduced to enhance the speed of ridge regression estimator calculation through series expansion and computation recycle without adopting an inverse matrix in the calculation process or other factorization methods. In addition, the performances of the proposed algorithm and the existing algorithm were compared according to the matrix size. Overall, excellent speed-up of the proposed algorithm with good accuracy was demonstrated.

• Journal of Sensor Science and Technology
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• v.32 no.1
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• pp.62-65
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• 2023

The wave mode calculation of a large-scale optical system in comparison to the working wavelength is practically impossible because the computational cost increases exponentially. In this paper, we propose a method that can obtain the optical mode in a large-scale optical system. The method carries out simulations by dividing the calculation area into blocks and moving along the light axis along which the light propagates. By applying this method to the calculation of resonant modes in a ring-type optical resonator, which is mainly used for ring laser optical gyro sensors, the efficiency of the proposed method was verified.

• Earthquakes and Structures
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• v.24 no.5
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• pp.365-375
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• 2023

Energy dissipation systems increase the energy dissipation capacity of buildings considerably. In this study, the effect of dampers on a typical 10-storey reinforced concrete structure with a ductile moment-resisting frame was investigated. In this context, 5 different models were created according to the calculation of the slip load and the positions of the dampers in the structure. Nonlinear time-history analyzes using 11 different earthquake acceleration records were performed on the models using the ETABS program. As a result of the analyses, storey displacements, energy dissipation ratios, drift ratios, storey accelerations, storey shears, and hysteretic curves of the dampers on the first and last storey and overturning moments are presented. In the study, it was determined that friction dampers increased the energy dissipation capacities of all models. In addition, it has been determined that positioning the dampers in the outer region of the structures and taking the base shear as a basis in the slip load calculation will be more effective.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.329-330
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• 2021

The calculation of the correct construction value in the construction should be investigated after the quantity is calculated. In order to calculate the quantity requires a lot of cost and time, and the initial accurate quantity calculation is not possible. Therefore, in the planning step in order to successfully complete the project to demonstrate the practicality of the difference between the construction cost by the construction design by presenting a method for calculate the quantity through the estimate with the construction open, floor plan, surface view, section.