• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.118-123
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• 2007

A robust objective function in the frequency domain is applied to the acoustic full waveform inversion. The proposed objective function is defined as $l_1$-norm of residual wavefields in the frequency domain. Generally, the full waveform inversion is extremely sensitive to a number of factors such as parameterization, initial model, noise and so on. The numerical tests were performed for checking the sensitivity to attenuation and several noises. For the comparison with other objective functions, the conventional least-squares method and the logarithmic method were tested under the same condition. The synthetic data examples show that the proposed algorithm is more robust than the well-known methods.

• Structural Engineering and Mechanics
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• v.25 no.3
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• pp.347-363
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• 2007

A novel methodology, referred to as Auxiliary Domain Method (ADM), allowing for a very efficient solution of nonlinear reliability problems is presented. The target nonlinear failure domain is first populated by samples generated with the help of a Markov Chain. Based on these samples an auxiliary failure domain (AFD), corresponding to an auxiliary reliability problem, is introduced. The criteria for selecting the AFD are discussed. The emphasis in this paper is on the selection of the auxiliary linear failure domain in the case where the original nonlinear reliability problem involves multiple objectives rather than a single objective. Each reliability objective is assumed to correspond to a particular response quantity not exceeding a corresponding threshold. Once the AFD has been specified the method proceeds with a modified subset simulation procedure where the first step involves the direct simulation of samples in the AFD, rather than standard Monte Carlo simulation as required in standard subset simulation. While the method is applicable to general nonlinear reliability problems herein the focus is on the calculation of the probability of failure of nonlinear dynamical systems subjected to Gaussian random excitations. The method is demonstrated through such a numerical example involving two reliability objectives and a very large number of random variables. It is found that ADM is very efficient and offers drastic improvements over standard subset simulation, especially when one deals with low probability failure events.

• Wind and Structures
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• v.9 no.4
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• pp.297-313
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• 2006

The concentration of air pollution along roads is higher than the surrounding area because ventilation efficiency has decreased due to the high-density use of space along roads in recent years. In this study, ventilation efficiency around a heavily traffic road covered by an elevated highway and hemmed in along its side by buildings is evaluated using Visitation Frequency (VF, the frequency for pollutant to return to the objective domain) and Purging Flow Rate (PFR, the air flow rate for defining the local domain-averaged concentration). These are analyzed using Computational Fluid Dynamics (CFD) based on the standard $k-{\varepsilon}$ model. The VF and PFR characteristics of four objective domains are analyzed in terms of the changes in wind direction and arrangements of the fencing dividing up and down direction in the road center under the elevated highway. The resulting VFs are more than 1.0 for all cases, which means that pollutants return to the objective domain restricted by the elevated highway and side buildings. The influence of the arrangement of the buildings around the objective domain and the structure in the domain on the VF is substantial. In cases where there are no obstacles under the elevated highway, the local air exchange rate in the domain tends to be improved. Using these indices, the urban ventilation efficiencies between different urban areas can be compared easily.

• Geophysics and Geophysical Exploration
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• v.22 no.4
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• pp.195-201
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• 2019

The logarithmic objective function used in waveform inversion minimizes the logarithmic differences between the observed and modeled data. Laplace-domain waveform inversions usually adopt the logarithmic objective function and the diagonal elements of the pseudo-Hessian for optimization. In this case, we apply the Levenberg-Marquardt algorithm to prevent the diagonal elements of the pseudo-Hessian from being zero or near-zero values. In this study, we analyzed the diagonal elements of the pseudo-Hessian of the logarithmic objective function and showed that there is no zero or near-zero value in the diagonal elements of the pseudo-Hessian for acoustic waveform inversion in the Laplace domain. Accordingly, we do not need to apply the Levenberg-Marquardt algorithm when we regularize the gradient direction using the pseudo-Hessian of the logarithmic objective function. Numerical examples using synthetic and field datasets demonstrate that we can obtain inversion results without applying the Levenberg-Marquardt method.

• Journal of Broadcast Engineering
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• v.10 no.4 s.29
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• pp.505-514
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• 2005

Image upsampling can be performed in both spatial and frequency (transform) domain. In the spatial domain, various upsampling techniques are developed and 6-tap FIR interpolation filter is most well known method, which is embedded in many video coding standards. It can provide high subjective quality but shows low objective quality. In the transform domain, simple zero padding method can produce upsampled image easily. It shows better objective quality than 6-tap filtering, but it yields ringing effects which annoy eyes. In this paper, we present efficient upsampling method using frequency addition method in transform domain to provide better subjective and objective quality than conventional method Extensive simulation results show that the proposed algorithm produces visually fine images with high PSNR.

• Journal of Korean Elementary Science Education
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• v.24 no.1
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• pp.86-101
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• 2005

In this study, a brain-basrd model for science teaching and learning was developed based on the natural processes which human acquire knowledge about a natural object or on event, the major domains of science educational objectives of the national curriculum, and the human brain's organizational patterns and functions. In the model, each educational objective domain is related to the brain regions as follows: The affective domain is related to the limbic system, especially amygdala of human brain which is involved in emotions, the psychomotor domain is related to the occipital lobes of human brain which perform visual processing, temporal lobes which perform functions of language generating and understandng, and parietal lobes which receive and process sensory information and execute motor activities of body, and the cognitive domain is related to the frontal and prefrontal lobes which are involved in think-ing, planning, judging, and problem solving. The model is a kind of procedural model which proceed fiom affective domain to psychomotor domain, and to cognitive domain of science educational objective system, and emphasize the order of each step and authentic assessment at each step. The model has both properties of circularity and network of activities. At classrooms, the model can be used as various forms according to subjects and student characteristics. STS themes can be appropriately covered by the model.

• Journal of Korean Home Economics Education Association
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• v.15 no.1
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• pp.15-32
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• 2003

This study examined teacher perception of the instructional method. activities and material in terms of class quality enhancement. Also this study established instructional method. activities and material application Per 7th Practical Arts Education Course guidance domain. and type identification of the instructional method and activities unique to the Practical arts curriculum. Conclusions : 1. Teachers consider the instructional method and material beneficial. However in the item relevant to application of diverse instructional methods Per specific teaching objective and educational content in the actual classroom. the highest percentage responding. ‘relatively yes’ (39.7%) . balanced out with those answering. ‘no’(37.7%) 2. In linking the instructional method and material to secondary school home economics education, teachers experienced difficulty in teaching only the clothing education domain . 3. In each guidance domain, lecture method, problem-solving learning. cooperative learning. home project learning and functional learning were surveyed for instructional method suitability. Notably, home project learning was identified as a significant instructional method. This result begs in-dept analysis as home project learning may be utilized as a tool to compensate for the absence of practical educational objective condition fulfillment and to substitute for teachers unable to Provide such functional guidance in class. 4. In each guidance domain. role-playing. debate/discussion. case study research, practical exercise and activity reporting were rated as essential teaching ㆍ learning activities. 5. In each guidance domain.‘VCR’, ‘CD-ROM’ and ‘Web media’ were identified as suitable instructional materials .

• Hwankyungkyoyuk
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• v.14 no.2
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• pp.28-39
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• 2001

The purpose of this study is to understand the characteristics and the differences regarding the teaching & learning objectives of Environment textbooks for middle school students with the consideration of the 7th Korean National Curriculum. For this the teaching & teaming objectives of three Environment textbooks currently used categorized according to the domain frame of environmental education in the Report of UNESCO(1980). three Environment textbooks and their teacher's guide books are those printed by three companies(A, B, and C) and Joongahng co.. The five objective categories recommended by UNESCO are awareness, knowledge, attitude, skills and participation and six types of skills by National Curriculum Council of England are communication skills, numeracy skills, study skills, problem-solving skills, personal and social skills and information technology skills. It is showed that'Human and Environment'domain is emphasized roughly in the awareness and the knowledge section without any statement of the participation section, 'Environmental Problems and its Counter-plan'domain in the knowledge and the skills section, 'Environmental Conservation'domain in the skills and the participation section of objectives. It is revealed that the skills section of the teaching 8t learning objectives is mainly involved in 'Environmental Problems and its Counter-plan'domain and'Environmental Conservation' domain. According to the result of the analysis of the connectivity between the Environment Curriculum of the 7th Korean National Curriculum and the Environment textbooks regarding objectives stated in the sub-domain level, it says those are generally appropriate ones. But some objectives are emphasized weakly or not at all in several sub-domains such as'The living environment to keep','The environmental problems of the earth','Making environment pleasant'. It is proposed that the efforts to state objectives in the Environment textbooks evenly are needed to be paid (or the well-balanced teaching & teaming of the Environment subject.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.872-873
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• 2011

This paper presents a multi-domain topology optimization using the harmonically excited coil and the iron in order to focus pulsed magnetic field (PMF). The design sensitivity of the harmonic magnetic field is derived by adjoint variable method. As a result of the optimization, PMF is considerably concentrated on the objective domain with much less leakage than the initial model.

• The Journal of the Acoustical Society of Korea
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• v.16 no.2E
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• pp.38-46
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• 1997

The objective of the paper is to compare the computational complexity of five algorithms for computing time-domain second-order Volterra filter outputs in terms of number of real multiplication and addition operations required for implementation. This study shows that if the filter memory length is greater that or equal to 16, the fast algorithm using the overlap-save method and the frequency-domain symmetry properties of the quadratic coefficients is the most efficient among the algorithms investigated in this paper, When the filter memory length is less than 16, the algorithm using the time-domain symmetry properties is better than any other algorithm.