• 대한수학교육학회지:수학교육학연구
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• 제12권1호
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• pp.17-27
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• 2002

To solve the addition word problems provides young children the chance to learn about and exercise in problem solving. This paper focuses on two aspects to be considered in addition word problems: the homogeneity of objects and the variety of contexts. The homogeneity of objects involved in addition word problems has to be kept in the following reasons: concept of unit, effectiveness of information, prevention of inappropriate variety, inconsistency of mathematics with real world, continuity between elementary and secondary mathematics. And for the variety of contexts, the additive structure proposed by G. Vergnaud, can be considered: composition, transformation, relation of comparison, composition of two transformations, composition of two relations, transformation of a relation. According to this structure, some examples, which contain homogeneous objects, were extracted from the elementary school mathematics textbooks.

• Journal of Computing Science and Engineering
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• 제4권2호
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• pp.97-109
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• 2010

Nonnegative matrix factorization (NMF) is a popular method for multivariate analysis of nonnegative data, which is to decompose a data matrix into a product of two factor matrices with all entries restricted to be nonnegative. NMF was shown to be useful in a task of clustering (especially document clustering), but in some cases NMF produces the results inappropriate to the clustering problems. In this paper, we present an algorithm for orthogonal nonnegative matrix factorization, where an orthogonality constraint is imposed on the nonnegative decomposition of a term-document matrix. The result of orthogonal NMF can be clearly interpreted for the clustering problems, and also the performance of clustering is usually better than that of the NMF. We develop multiplicative updates directly from true gradient on Stiefel manifold, whereas existing algorithms consider additive orthogonality constraints. Experiments on several different document data sets show our orthogonal NMF algorithms perform better in a task of clustering, compared to the standard NMF and an existing orthogonal NMF.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제18권1호
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• pp.1-29
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• 2014

When taught the precise definition of ${\pi}$, students may be simply asked to memorize its approximate value without developing a rigorous understanding of the underlying reason of why it is a constant. Measuring the circumferences and diameters of various circles and calculating their ratios might just represent an attempt to verify that ${\pi}$ has an approximate value of 3.14, and will not necessarily result in an adequate understanding about the constant nor formally proves that it is a constant. In this study, we aim to investigate prospective teachers' conceptual understanding of ${\pi}$, and as a constant and whether they can provide a proof of its constant property. The findings show that prospective teachers lack a holistic understanding of the constant nature of ${\pi}$, and reveal how they teach students about this property in an inappropriate approach through a proving activity. We conclude our findings with a suggestion on how to improve the situation.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2009년도 춘계학술발표회 논문집
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• pp.91-94
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• 2009

항공사진촬영은 계획된 노선을 따라 항공기를 조정하여 적절한 위치에서 촬영을 수행하는 작업이다. 특히 3차원 공간데이터 구축을 위하여 사용되는 다각사진촬영시스템의 경우 대형 CCD가 중형 CCD를 사용함으로써 촬영면적이 크지 않아서 적절한 위치에서 촬영이 이루어 지지 않는 경우 충분한 중복도를 확보하지 못하여 외부표정요소 결정에 문제가 발생할 소지가 있다. 따라서, GPS/INS를 이용하여 정확한 항공기의 위치를 결정하여 사전에 계획된 위치에서 촬영을 실시함으로써, 정확한 3차원 공간데이터의 모델링을 수행할 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1908-1909
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• 2007

The design of an intelligent toothbrush, capable of monitoring brushing motion, orientation through the grip axis, during toothbrushing is described. Inappropriate Toothbrushing styles, even in adults, sometimes cause dental problems, cavities, gingivitis, etc. This smart system provides user to monitor his or her brushing pattern using accelerometer and magnetic sensors for evaluation of toothbrushing style. Directional information of toothbrush with respect to earth's magnetic field and activity data were measured by a miniaturized low-power micro- controller, MSP430 and transmitted to personal computer by 2.4GHz radio transmitter, nRF2401. A personal computer provides an on-line display of activity and orientation measurements during toothbrushing. The signal trace is then analyzed to extract clinically relevant measurement. This preliminary study showed that the proposed monitoring system was conceived to aid dental care personnel in patient education and instruction in oral hygiene regarding brushing style.

• Tribology and Lubricants
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• 제20권3호
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• pp.132-139
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• 2004

Many researches about the contacts between cam and follower have investigated EHL film thickness either without dynamic loading effect or only with curve fitting formula such as Dowson-Hamrock's, because including squeeze film effect makes it hard to obtain convergence and stability of computation. Therefore, inaccurate information about minimum film thickness without dynamic loading condition causes inappropriate design of cam profiles and wrong selection of cam and follower materials. In this work, computation tools both for kinematics and dynamics of valve train system of push-rod type and for fluid film thickness with elastic deformation on the basis of dynamic loading condition with multigrid multi-level method is developed. The computational results of minimum film thickness with the respects of both static and dynamic loading conditions are compared for the contact of flat follower over the entire cycle.

• 한국축산시설환경학회지
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• 제18권sup호
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• pp.7-12
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• 2012

To prevent the inappropriate treatment of livestock manure and induce the correct circulation of them into farmland, systematic monitoring and management by the treatment and circulation stage of livestock manure are required. The purpose of this study was to apply ubiquitous information communictation technology (u-ICT) to a livestock waste management system for better treatment by utilizing ubiquitous computing technology in the livestock sector. Elements and levels of applicable u-ICT technology for efficient livestock manure management were derived by analyzing previous researches. In addition, a conceptual diagram of an integrated management system was suggested by analyzing the existing liquid fertilization process.

• 여성건강간호학회지
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• 제15권2호
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• pp.140-149
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• 2009

Purpose: The purposes of this phenomenological study were to explore the experience of preterm labor. Methods: The participants were 7 women admitted to two obstetric hospitals in Kyunggi-do Province with preterm labor. Data was collected with MP3 records through individual in-depth interviews and participated observation. The data was analyzed by Giorgi(1985) method. Results: The results were divided into six categories as follows: 1) Inappropriate coping: unexpected event, overwork, lack of insight of preterm labor, 2) Burn out: multiple role, burden, role conflict. 3) Restrictions of lifestyle: uncomfortable hospital environment, wearisomeness, limitations of personal hygiene, 4) Physical discomfort: headache, flush, tremor, palpitations, 5) Psychological distress : concerns about fetus health status, fear of possible preterm delivery, lack of information, financial worries, 6) A transition to new lifestyle: share of household chores, communication with self-help group, careful lifestyle. Conclusion: The findings of this study will offer a better understanding of women's preterm labor experiences and suggest clues to nurses on how to improve the care they provide.

• Current Optics and Photonics
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• 제4권4호
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• pp.345-352
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• 2020

We describe a calibration method to improve the accuracy of interferometric snapshot spectroscopic ellipsometry employing a dual-spectrometer sensor scheme. Conventional spectral wavelength calibration of a spectrometer has been performed by using a calibration lamp having multiple peaks at specific wavelength. This paper shows that such a conventional spectrometer calibration method is inappropriate for the proposed interferometric snapshot spectroscopic ellipsometry to obtain highly accurate ellipsometric phase information. And also, systematic error analysis of interferometric snapshot spectroscopic ellipsometry is conducted experimentally.

• 대한방사선기술학회지:방사선기술과학
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• 제42권4호
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• pp.301-308
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• 2019

This study reviewed whether radiology-related pictograms listed on the website of hospitals deliver clearly, accurately and quickly the necessary information. TOPSIS was carried out to select the most fitting pictograms for the department of radiology, department of radiation oncology, and department of nuclear medicine. The finally selected pictogram for the department of radiology shows an image of the chest (lungs), while that for the department of radiation oncology shows the process of treatment using equipment. Using these pictograms as standards seem to be appropriate to a certain level. However, the pictogram for department of nuclear medicine has a symbol for a nucleus and is thus inappropriate to meet the standards for a hospital pictogram. This study is meaningful in that it has established evaluation methods and procedures relaetd to radiation pictograms.