• Journal of Korean Ophthalmic Optics Society
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• v.7 no.1
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• pp.57-61
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• 2002

Ternary $SrO-B_2O_3-SiO_2$ glasses were fabricated as a function of R(${\equiv}SrO\;mole%/B_2O_3\;mole%$) and K(${\equiv}SiO_2\;mole%/B_2O_3\;mole%$). The structures of these glasses were investigated through Infrared transmittance, vicker's hardness, and refractive index. The results indicated : First, in the infrared transmittance spectra, when R increased, the intensities of the absorption bands around $1200{\sim}1600cm^{-1}$ resulting from the B-O stretching vibration bond in the symmetrical trigonal $BO_3$ units decreased, and these of the absorption bands around $800{\sim}1200cm^{-1}$ caused by the B-O stretching vibration bond of the tetrahedral $BO_4$ units varied. Also, the intensities of the absorption bands for the B-O stretching vibration bond in trigonal $BO_3$ units increased and these of the bands for B-O stretching vibration bond in tetrahedral $BO_4$ units decreased as K increased. Second, the increase and the decrease of vicker's hardness values for these glasses depended on the fraction of $BO_4$ units and it of $BO_3$ units, respectively. The refractive index of these glasses mostly depended on the SrO contents and only slightly depended on the fraction of $BO_4$ and $BO_3{^-}$ units.

• School Mathematics
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• v.19 no.2
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• pp.385-403
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• 2017

This paper analyzed the units of capacity and weight in the mathematics textbooks in terms of units, relationship between the units, and the need of standard units. The results of this study showed that there were differences in the representation of the units, the notation of units, the types of units, and the representation of basic amount of units in the mathematics textbooks developed by the 5th, 6th, 7th, 2007 revised, and 2009 revised national mathematics curriculum respectively. The mathematics textbook developed by the 2009 revised mathematics curriculum was found to be generally consistent with the International System of Units (SI). However, the way of defining 1kg through the weight of water was found to be different from the SI. The relationship between the units was consistently described only with a written sentence in the previous mathematics textbooks, but the 2009 revised mathematics textbook presents questions and pictures to foster students' understanding of the relationship. Finally, activities and questions are required for students to recognize the universality and convenience of the standard units through the inconvenience of arbitrary units. Based on these results, this paper provides implications for the development of mathematics textbooks in the units of capacity and weight.

• Journal of Korean Society for Quality Management
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• v.6 no.1
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• pp.27-30
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• 1978

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1985.10a
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• pp.164-169
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• 1985

• Journal of the Korean Society of Radiology
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• v.4 no.2
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• pp.31-35
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• 2010

In this study, we surveyed students recognition of the base units and radiation related units among international standard units, and determined the necessity of unit education. The survey was conducted using a questionnaire composed of 18 questions, and in the survey, students at the Radiology Department were asked about recognition and education. According to the results of the survey, around 44% of the students answered wrongly on base unit kV, and around 28% answered wrongly on km. Particularly with regard to the relation between units and numbers, around 57% of the students chose wrong answers. As to prefix mega and giga, respectively, 22% and 20% of the students chose wrong answers. To the question on radiation related unit Sv, around 30% gave wrong answers. Recognition of radiation related units was higher in senior students. To the question of whether to have received special education on units, over 50% of the students replied negatively. These results suggest the necessity of education on international standard units.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.6
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• pp.454-458
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• 2009

The technology of virtual environments has been developed with better-quality appearance on a computer display in mind, but without consideration for objects' precise measurements in physical units. With the increased application of computer graphics in a variety of areas, there is a need for precise measurement functionality in addition to visualization. This paper describes the definition of physical properties using measurement units for X3D based virtual objects, to provide their precise physical information in virtual environments. To this end, we have included the physical property node in the X3D specification. The physical measurement units, such as length, mass, time, temperature, etc., are based on SI units (International System of Units).

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.27-31
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• 2002

Quarternary $Li_2O-B_2O_3-Al_2O_3-SiO_2$ glasses were fabricated by the function of $R({\equiv}Li_2Omole%/B_2O_3mole%)$ and $K({\equiv}(Al_2O_3mole%+SiO_2mole%/B_2O_3mole%)$. The structures of these glasses were investigated through refractive index and Vicker's hardness. The refractive index increased as the increase of the polarizability in the glass network. In the region of low $Li_2O$ content, the refractive index increased due to the increase of the polarizability in the glass network but, in the region of high $Li_2O$ content, the rate of increase of the refractive index decreased due to the increase of the molar volume caused by the formation of $BO_3{^-}$ units with relatively high molar volume. And, the refractive index decreased as the increase of $Al_2O_3+SiO_2$ content with the molar volume in the glass network. The increase and decrease of vicker's hardness values for those glasses depended on the fraction of tetrahedral $BO_4$ units and it of triangle $BO_3{^-}$ units with non-bridging oxygen, respectively.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.7-10
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• 2003

Quarternary $SrO-B_2O_3-Al_2O_3-SiO_2$ glasses were fabricated as a function of $R({\equiv}SrO\;mole%/B_2O_3\;mole%)$ and $K({\equiv}(Al_2O_3+SiO_2)\;mole%/B_2O_3\;mole%)$. The structures of these glasses were investigated through Infrared absorption spectra. When R increased, the intensities of the absorption bands around $1,200{\sim}1,600cm^{-1}$ resulting from the B-O stretching vibration bond in the symmetrical trigonal $BO_3$ units decreased, and these of the absorption bands around $800{\sim}1,200cm^{-1}$ caused by the B-O stretching vibration bond of the tetrahedral $BO_4$ units varied. Also, the intensities of the absorption bands for the B-O stretching vibration band in trigonal $BO_3$ units increased and these of the bands for B-O stretching vibration bond in tetrahedral $BO_4$ units decreased as K increased.

• The Monthly Technology and Standards
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• s.5
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• pp.41-42
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• 2002

• Product Safety
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• no.4 s.148
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• pp.24-31
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• 2006