• Education of Primary School Mathematics
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• v.23 no.3
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• pp.135-156
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• 2020

The purpose of this study is to analyze the effect of average unit learning on the knowledge of the representative value of 5th grade elementary school students. In the information-oriented society, the ability to organize and summarize the data has become an essential resource. In the process of correctly analyzing statistical data and making reasonable decisions, the summary of the data plays an important role, and it is necessary to learn the concept of representative values in order to describe the center of the data in a series of numbers. For research, an informal knowledge type possessed by a fifth grade elementary school student with respect to a representative value before learning an average unit is examined and compared with the representative value after learning the average unit. A suggestion point for representative value guidance in school mathematics is provided while examining the change in knowledge with respect to the representative value. Seeing the informal types of elementary school students' representative values will help them learn how to formalize the concept of representative values in middle and high schools. It will give suggestions about the concept of representative values and the method of instruction that should be dealt with in elementary schools. The informal knowledge about the representative value can help with formal representative value that will be learned later. Therefore, This study's discussions on statistical learning of elementary school students are expected to present meaningful implications for statistical education.

• Journal of Educational Research in Mathematics
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• v.22 no.3
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• pp.429-444
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• 2012

As one of the trials for a systematic approach to mathematics terms which occupies an important place in teaching and learning mathematics, compositions of listed terms in 2011 elementary mathematics curriculum in Korea are discussed in this study. To this end, listed terms are classified in view of three points and looked for their characteristics, from which implications are found out for elementary mathematics teaching and learning First of all classifications into grade-group and domain-specific terms, then into newly coined terms and terms from everyday life, and then into korean terms and chinese character terms and english terms are attempted. Next, terms with a kernel and terms without a kernel are distinguished, and in this process, term-sets are presented. Finally, object terms, operation terms, relationship terms, measure terms, conditions terms, graphics terms, name terms are classified. Based on these results, the following implications for elementary mathematics teaching and learning are suggested. First, it should be considered that many of the listed terms in 2011 curriculum are newly coined and chinese character terms. Second, the interconnections between terms should be considered. Third, a variety of roles and functions of the terms should be considered.

• School Mathematics
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• v.8 no.4
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• pp.379-396
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• 2006

The purpose of this study is to analyze characteristics of problem solving in mathematics for gifted students through case study on solving the mathematical problem for gifted students, and to investigate what are relationships with the cognitive and affective characteristics. To this end, this study was to analyze the characteristics on the problem solving in mathematics by using qualitative research method after it selected two students who had specific education for brilliant students. As a result, this study has shown that it had high preference for question with clear answer, high preference for individual inquiry learning, high adhesion to answer for question, and high adhesion for assignment on characteristics of process of problem solving, but there was much difference in spirit of competition. As to the characteristics of thoughts in problem solving, this study has shown that it had high grasp capacity, intuitive insight, and capacity for visualization, but there were differences in capacity for generalization and adaptability. However, both two students had low values in deductive thought. In addition, as to the home environment and cognitive and affective characteristics, they were not related to the characteristics on problem solving directly, but it has shown that it affected each other indirectly. As to the conclusion of this study, this researcher thinks that it will be valuable documentation in order to improve curriculum, development of textbooks, and teaching method for special education for the gifted students and education for secondary mathematics.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.92-100
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• 2011

This paper describes a numerical modeling for deflection calculation using the natural frequency response that is measured acceleration response for concrete bridges. In the formulation of the dynamic deflection, the change amounts and the transformed responses about six kinds of free vibration responses are defined totally. The predicted response can be obtained from the measured acceleration data without requiring the knowledge of the initial velocity and displacement information. The relationship between the predicted response and the actual deflection is derived using the mathematical modeling that is induced by the process of a acceleration test data. In this study, in order to apply the proposed response predicted model to the integration scheme of the natural frequency domain, the Fourier Fast Transform of the deflection response is separated into the frequency component of the measured data. The feasibility for field application of the proposed calculation method is tested by the mode superposition method using the PSC-I bridges superstructures under several cases of moving load and results are compared with the actually measured deflections using transducers. It has been observed that the proposed method can asses the deflection responses successfully when the measured acceleration signals include the vehicle loading state and the free vibration behavior.

• Korean Journal of Construction Engineering and Management
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• v.11 no.4
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• pp.22-31
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• 2010

Because the estimated cost at early stage has great influence on decisions of project owner, the importance of early cost estimation is increasing. However, it depends on experience and knowledge of the estimator mainly due to shortage of information. Those tendency developed into case-based reasoning(CBR) method which solves new problems by adapting previous solution to similar past problems. The performance of CBR model is affected by attribute weight, so that its accurate determination is necessary. Previous research utilizes mathematical method or subjective judgement of estimator. In order to improve the problem of previous research, this suggests CBR schematic cost estimation method using genetic algorithm to determine attribute weight. The cost model employs nearest neighbor retrieval for selecting past case. And it estimates the cost of new cases based on cost information of extracted cases. As the result of validation for 17 testing cases, 3.57% of error rate is calculated. This rate is superior to accuracy rate proposed by AACE and the method to determine attribute weight using multiple regression analysis and feature counting. The CBR cost estimation method improve the accuracy by introducing genetic algorithm for attribute weight. Moreover, this makes user understand the problem-solving process easier than other artificial intelligence method, and find solution within short time through case retrieval algorithm.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.2
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• pp.133-141
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• 2017

The hybrid acoustic sensor for implantable hearing aid has the structure in which a sound pressure based acoustic sensor (ECM) and a vibration based acceleration sensor are combined. This sensor combines the low frequency sensitivity of an acoustic sensor with the high frequency sensitivity of an acceleration sensor, allowing the acquisition of a wide range of sound from low to high frequency. In this paper, an acceleration sensor for use in a hybrid acoustic sensor has been proposed. The acceleration sensor captures the vibration of the tympanic membrane generated by the acoustic signal. The size of the proposed acceleration sensor was determined to diameter of 3.2 mm considering the anatomical structure of the tympanic membrane and the standard of ECM. In order to make the hybrid acoustic sensor have high sensitivity and wide bandwidth characteristics, the aim of the resonance frequency of the acceleration sensor is to be generated at about 3.5 kHz. The membrane of the acceleration sensor derives geometric structure through mathematical model and finite element analysis. Based on the analysis results, the membrane was implemented through a chemical etching process. In order to verify the frequency characteristics of the implemented membrane, vibration measurement experiment using external force was performed. The experiment results showed mechanical resonance of the membrane occurred at 3.4 kHz. Therefore, it is considered that the proposed acceleration sensor can be utilized for a hybrid acoustic sensor.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.76-85
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• 1993

In order to predict the free surface signature of turbulent ship wakes two things are essential; a basic understanding of the mechanism of turbulent vortical flow/free surface interactions and a mathematical model to accurately predict the signature. The goal of the study described here is both to supplement experimental work to obtain basic understanding, as well as to condense this understanding in a model(or models) that captures the essential phenomena and thus allows predictions. To do so we followed two main paths guided by experimental observations. One is full simulations of the flow using the clavier-Stokes equations. The other is a vortex modeling, where the vortical structures of the flows are approximated by idealized structures, an the interaction assumed to be essentially inviscid. These approaches complement each other. Full simulations are only applicable to small scale phenomena, where the system is simple, and the Reynolds number is low. The vortex modeling, on the other hand, cannot represent essentially viscous aspects of the problem such as the effect of contamination gradient. Obviously, the modeling is what may eventually lead to a prediction method; the full simulations-too limited to mimic all but the simplest circumstances-are to aid and support the construction of realistic models. We address two-dimensional aspects of the vortex/free surface interaction first. Secondly we obtain some basic understanding of the interaction process through an experiment and then talk about several three-dimensional problems hoping to develop a successful prediction model.

• Korean Business Review
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• v.14
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• pp.31-44
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• 2001

The purpose of auditing is to express an auditor's opinion on the fair presentation of the financial position and business operations of companies according to the financial accounting standards, and to raise the reliability of the financial statements and to enable the user of the financial statements to make a proper judgement on the companies. There should be an audit risk in the audit of the financial statements in a modem sense because it is done by the sampling audit not by the detailed one. Audit risk is the risk that an auditor may unknowingly fail to modify appropriately the auditors' report on financial statements containing a material misstatement. The audit risk eventually hurt the reliability of the financial statements when the auditors set up different audit risks because it is determined by the auditor's professional judgement. Thus, there have been negative opinions on the Audit Risk Model suggested in the SAS No. 47 because it cannot explain the process of auditor's judgement and bring different results. In view of the results so far achieved, which influences the auditor's decision making, should be done by the Belief Function Mode Model in a position of raising the reliability of the financial statements and emphasizing the usefulness and effectiveness of the auditing.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.2 s.308
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• pp.21-32
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• 2006

The license plate recognition (LPR) unit consists of the following core components: plate region segmentation, individual character extraction, and character recognition. Out of the above three components, accuracy in the performance of plate region segmentation determines the overall recognition rate of the LPR unit. This paper proposes an algorithm for segmenting the license plate region on the front or rear of a vehicle in a fast and accurate manner. In the case of the proposed algorithm images are captured on the spot where unmanned monitoring of illegal parking and stowage is performed with a variety of roadway environments taken into account. As a means of enhancing the segmentation performance of the on-the-spot-captured images of license plate regions, the proposed algorithm uses a mathematical model for license plate colors to convert color images into digital data. In addition, this algorithm uses Gaussian smoothing and double threshold to eliminate image noises, one-pass boundary tracing to do region labeling, and MBR to determine license plate region candidates and extract individual characters from the determined license plate region candidates, thereby segmenting the license plate region on the front or rear of a vehicle through a verification process. This study contributed to addressing the inability of conventional techniques to segment the license plate region on the front or rear of a vehicle where the frame of the license plate is damaged, through processing images in a real-time manner, thereby allowing for the practical application of the proposed algorithm.

• Elastomers and Composites
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• v.34 no.2
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• pp.135-146
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• 1999

The thermal degradation kinetics of SBR and tire were studied using a conventional thermogravimetric analysis in the stream nitrogen at a heating rate of 5, 10, 15, $20^{\circ}C/min$, respectively. Thermogravimetric curves and their derivatives were analyzed using various analytical methods to determine the kinetic parameters. The degradation of the SBR and tire was found to be a complex process which has multi-stages. The Friedman method gave average activation energies for the SBR and tire of 247.53kJ/mol and 230.00kJ/mol, respectively. Mean-while, the Ozawa method Eave 254.80kJ/mol and 215.76kJ/mol. It would appear that either. Friedman's differential method or Ozawa's integral method provided satisfactory mathematical approaches to determine the kinetic parameters for the degradation of the SBR and tire. Approximately 86% and 55% of oil products were obtained at a final temperature of $700^{\circ}C$ and a heating rate of $20^{\circ}C/min$ for the SBR and tire respectively.