• Journal of Elementary Mathematics Education in Korea
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• v.21 no.1
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• pp.161-194
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• 2017

The aim of this study is to look into sub-factors of spatial sense that can be contained in spatial sense of solid figure of mathematics curriculum and offer suggestions to improve teaching spatial sense of solid figures in the future. In order to attain these purposes, this study examined the meaning and sub-factors of spatial sense and the relations between spatial sense of solid figure and sub-factors of spatial sense through a theoretical consideration regarding various studies on spatial sense. Based on such examination, this study compared and analyzed textbooks used in South Korea, Finland and the Netherlands with respect to contents of mathematics curriculum and textbooks in grades, sub-factors of spatial sense, and realistic contexts for spatial sense of solid figure. In the light of such theoretical consideration and analytical results, this study provided suggestions for improving teaching spatial sense of solid figures in elementary schools in Korea as follows: extending contents regarding spatial sense of solid figures in mathematics curriculum and considering continuity between grades in textbooks, emphasizing spatial orientation as well as spatial visualization, underlining not only construction with blocks but also mental activities in mental rotation and mental transformation, comparing strength and weakness of diverse plane representations of three dimensional objects, and utilizing various realistic situations and objects in space.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1976.06a
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• pp.87.1-87
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• 1976

Bekesy measured the sound transformation system of the middle ear 49 years ago. According to his reports, a ratio between the size of ear drum and the size of oval window is 17 : 1, and the lever function of the ossicles is physiologically 1.3 : 1. Therefore, the hearing might be aggravated to 27.5㏈ in the case of the vanishment of 3 ossicles. In 1952, Wullstein reported 5 types of tympanop-lasty and the fourth type among them was especially named for the sound-protection. The oval window is only exposed by the sound pressure and the round window is not exposed. According to the application by this idea, the post-operative hearing might be improved until 27.5㏈. Mean while, in 1942, Onchi verified through his experiment that the results of Bekesy's measurement was not completely conformed to Onchi result. Bekesy measured the sound pressure on the stapes plate of the oval window, on the other hand, Onchi measured the sound pressure on the surface of the perilymph of the oval window after removing the stapes plate(Fig. 1).(Figure omitted) The difference of their experiment is recognized that the impedance of the stapes plate exists or not (Fig. 1). Both Audiogrums are compared as Fig. 2. The result of IV type of tympanoplasty is success ful in 54% as the Table 1. (Table Omitted) The reason of unsatisfactory is caused by the thick and unmovable window-membrane and by the closing of air passage to the round window. The closing of the air passage to the round window is occurred by the adhesion between the grafting membrane and the surface of promontorium. In order to preserve this adhesion, I produce to transplantate the mucous membrane of the lip to the bone surface of tympanic cavity after removing the granulation tissue of the tympanic cavity and to form a membranous canal for the sake of air passage (Fig. 3). (Figure Omitted) The post-operative hearing by this method is shown as Fig. 4, 5. In other words, the post-operative sound pressure entered into the cochlea directly, by way of the oval window only, not by way of the round window, as a theorie of the sound protection. (Figure omitted)

• Journal of Elementary Mathematics Education in Korea
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• v.16 no.3
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• pp.359-388
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• 2012

The study aims to extract the framework of sub-factors of spatial sense, to develop test instruments based on the framework to investigate the actual spatial sense ability of fourth to sixth graders in elementary school and to analyze the results. According to the framework of sub-factors of spatial sense of the study, spatial sense has two factors of spatial visualization and spatial orientation. Spatial visualization is divided into mental rotation, mental transformation and figure-ground perception while spatial orientation is categorized into direction sense, distance sense, and location sense. Based on the framework, the test instrument for spatial sense ability was developed and the test was conducted to 430 fourth to sixth students in five elementary schools in capital areas. The following conclusions were drawn from the results obtained in the study. Firstly, the higher school year gets, the more spatial sense grows. However, spatial visualization is developed much more than spatial orientation and their order is reversed with higher graders. Secondly, the most insufficient abilities among fourth to sixth elementary school students' spatial sense were mental transformation of spatial visualization and location sense of spatial orientation. Thirdly, the reasons of differences in sub-factors of spatial sense and graders seem to be from effects of students' learning experiences of spatial sense of mathematics curriculum and the complexities of test items.

• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.47-53
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• 2014

This paper presents a high gain and high harmonic rejection low-noise amplifier (LNA) for software-defined radio receiver. This LNA exploits the high quality factor (Q) series resonance technique. High Q series resonance can amplify the in-band signal voltage and attenuate the out-band signals. This is achieved by a source impedance transformation. This technique does not consume power and can easily support multiband operation. The chip is fabricated in a $0.13-{\mu}m$ CMOS. It supports four bands (640, 710, 830, and 1,070MHz). The measured forward gain ($S_{21}$) is between 12.1 and 17.4 dB and the noise figure is between 2.7 and 3.3 dB. The IIP3 measures between -5.7 and -10.8 dBm, and the third harmonic rejection ratios are more than 30 dB. The LNA consumes 9.6 mW from a 1.2-V supply.

• Journal of architectural history
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• v.18 no.2
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• pp.47-63
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• 2009

This study focused on changes in form and spatial uses of Urban Hanok in Bukchon, Seoul. There are 10 representative cases which have been renovated through the policy of 'Preservation & Regeneration of Bukchon' by Seoul metropolitan government and other experts. Changes in form and spatial uses of Urban Hanok in Buckon are as follows. First, Changes of scale. Trough removing extension parts, facade of renovated Hanoks are 'transformed' into recovering their identity. Using basements or lofts, intensive application of spaces is transformation which promotes the vitality of Hanoks. Second, changes of space organization. As Hanok changes its function from residence to commercial or cultural use, il a1so changes space character or reorganizes space organization. It is important that deciding function of Hanok has to adjust its scale and organization. Third, changes of construction performance. Through introducing new material and constructing method, performance of wall has been changed respecting its wooden structure and interior-exterior figure. However, technical studies must back it up not to destroy its value of eco-friendly architecture. Fourth, changes of facility systems, like floor heating system. They changes floor level of Hanok equally, and then sections of Hanok have became simple. Furthermore, inserting new facility space, such as boiler room, stand-up kitchen, bathroom and toilet, organization of space also changed. It is necessary that wise alternative proposal through the method of transformation or mutation must be presented. These four changes can be classification into method of 'transformation' and 'mutation'. Changes of scale are method of transformation and changes of space organization are method of mutation. Also, while changes of construction performance are mutation, changes of facility systems are transformation. Recently, as price of lots have been increased, a lot of Hanoks have been commercialized. Thc commercial energy threat 'the identity of Bukchon as residential area'. From now on, to operate 'identity' and 'vitality' complementary, it is necessary to make up for the preservation policy of Hanok and consolidate renovating standards of Hanok which correspond to character of particular region and building usage.

• Bulletin of the Korean Mathematical Society
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• v.26 no.1
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• pp.47-52
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• 1989

Methods of Riemannian geometry has played an important role in the study of compact transformation groups. Every effective action of a compact Lie group on a differential manifold leaves a Riemannian metric invariant and the study of such actions reduces to the one involving the group of isometries of a Riemannian metric on the manifold which is, a priori, a Lie group under the compact open topology. Once an action of a compact Lie group is given an invariant metric is easily constructed by the averaging method and the Lie group is naturally imbedded in the group of isometries as a Lie subgroup. But usually this invariant metric has more symmetries than those given by the original action. Therefore the first question one may ask is when one can find a Riemannian metric so that the given action coincides with the action of the full group of isometries. This seems to be a difficult question to answer which depends very much on the orbit structure and the group itself. In this paper we give a sufficient condition that a subgroup action of a compact Lie group has an invariant metric which is not invariant under the full action of the group and figure out some aspects of the action and the orbit structure regarding the invariant Riemannian metric. In fact, according to our results, this is possible if there is a larger transformation group, containing the oringnal action and either having larger orbit somewhere or having exactly the same orbit structure but with an orbit on which a Riemannian metric is ivariant under the orginal action of the group and not under that of the larger one. Recently R. Saerens and W. Zame showed that every compact Lie group can be realized as the full group of isometries of Riemannian metric. [SZ] This answers a question closely related to ours but the situation turns out to be quite different in the two problems.

• Management Science and Financial Engineering
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• v.14 no.2
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• pp.89-104
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• 2008

Growth curves including Bass, Logistic and Gompertz functions are widely used in forecasting the market demand. Nonlinear least square method is often adopted for estimating the model parameters but it is difficult to set up the starting value for each parameter. If a wrong starting point is selected, the result may lead to erroneous forecasts. This paper proposes a method of selecting starting values for model parameters in estimating some growth curves by nonlinear least square method through grid search and transformation into linear regression model. Resealing the market data using the national economic index makes it possible to figure out the range of parameters and to utilize the grid search method. Application to some real data is also included, where the performance of our method is demonstrated.

• The Mathematical Education
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• v.52 no.4
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• pp.567-586
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• 2013

The purpose of this study was to introduce the Knowledge Quartet (KQ) framework by which we can analyze teacher knowledge revealed in teaching mathematics. Specifically, this paper addressed how the KQ framework has been developed and employed in the context of research on teacher knowledge. In order to make the framework accessible, this paper analyzed an elementary school teacher's knowledge in teaching her fifth grade students how to figure out the area of a trapezoid using the four dimensions of the KQ (i.e., foundation, transformation, connection, and contingency). This paper is expected to provide mathematics educators with a basis of understanding the nature of teacher knowledge in teaching mathematics and to induce further detailed analyses of teacher knowledge using some dimensions of the KQ framework.

• Communications for Statistical Applications and Methods
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• v.26 no.6
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• pp.591-610
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• 2019

Deep Learning is one of the machine learning methods to find features from a huge data using non-linear transformation. It is now commonly used for supervised learning in many fields. In particular, Convolutional Neural Network (CNN) is the best technique for the image classification since 2012. For users who consider deep learning models for real-world applications, Keras is a popular API for neural networks written in Python and also can be used in R. We try examine the parameter estimation procedures of Deep Neural Network and structures of CNN models from basics to advanced techniques. We also try to figure out some crucial steps in CNN that can improve image classification performance in the CIFAR10 dataset using Keras. We found that several stacks of convolutional layers and batch normalization could improve prediction performance. We also compared image classification performances with other machine learning methods, including K-Nearest Neighbors (K-NN), Random Forest, and XGBoost, in both MNIST and CIFAR10 dataset.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.298-301
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• 2004

In the last ten years, manufacturing companies like GE, IBM, Motorola and service companies like GE Capital and CITIBANK have realized that Six Sigma has standed for quality reform movemant. Six Sigma management which makes the critic effects on the quality management have enlarged and applied office indirect work process and service department as well beyond question manufacturing process. Then Can Six Sigma application methodology from manufacturing industry be applied to service industry without transformation? Can Six Sigma be applied on improvement of Information system quality which is the critic key figure of current successful companies? These questions would be resolved by conducting researches about application and evaluation of Six Sigma on manufacturing industry and service industry. This paper will furnish information of Six Sigma's new function for future business situation through comparing those researches