• Journal of Korean Ophthalmic Optics Society
• /
• v.8 no.1
• /
• pp.1-5
• /
• 2003

Quarternary $Na_2O-B_2O_3-Al_2O_3-SiO_2$ glasses were fabricated by the function of $R({\equiv}Na_2O\;mole%/B_2O_3\;mole%)$ and $K({\equiv}(Al_2O_3\;mole%+SiO_2\;mole%)/B_2O_3mole%)$. 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 $Na_2O$ content, the refractive index increased due to the increase of the polarizability in the glass network, but in the region of high $Na_2O$ 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.

• Economic and Environmental Geology
• /
• v.36 no.6
• /
• pp.511-525
• /
• 2003

The Okcheon Group in the southwestern part of the Okcheon Metamorphic Belt is subdivided into two distinct tectonostratigraphic units: the Boeun unit in the south and the Pibanryeong unit in the north. The Boeun unit consists of petites, psammites, carbonaceous petites, limestones and pebble-bearing quartzites. The Pibanryeong unit is composed of petites, well-sorted fine-grained psammites, carbonaceous psammites and quartzites. In order to outlining stratigraphy and depositional environments of the Okcheon Group, detailed stratigraphic sections were measured in three locations; one section(Gosan section) of the Boeun unit and two sections(Sorungjae and Hwangryeongzae sections) of the Pibanryeong unit. The Gosan section of the Boeun unit is interpreted to be deposited in the shallow marine environments, whereas the Sorungjae and Hwangryeonaiae sections of the Pibanryeong unit appear to be deposited in slope and deep basin environments. This result indicates rapid subsidence between deposition of the Boeun and Pibanryeong units in sedimentary environment. The trace of sedimentological environments in the Hwasan area was investigated by geochemical analysis of 109 metapelitic and psammitic rock samples. Distinct chemical variations of politic and psammitic rocks from the Boeun and Pibanryeong units in the study area are evident from plots of major elements and $A1_2O_3$/$SiO_2$ versus Basicity Index($Fe_2O_3{＋}MgO$)/($SiO_2{＋}K_2O{＋}Na_2O$). The rocks show a progressive chemical trend from the Boeun unit to the Pibanryeong unit on these diagrams. They in the southern sector of the Boeun unit display lower values and a comparatively wide range of $A1_2O_3$/$SiO_2$ and Basicity Index, as compared with those from the northern sector of the Boeun and Pibanryeong units. The southern sector of the Pibanryeong unit including narrow staurolite-bearing zone is characterized by values that are transitional between the Boeun and Pibanryeong units. These data, combined with depositional environment progressively deepened towards the northwest, support a half-graben model for the Okcheon basin, as proposed by Cluzel et al.(1990)

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

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.38 no.5
• /
• pp.18-21
• /
• 1996

• Journal of the Speleological Society of Korea
• /
• v.14 no.15
• /
• pp.42-90
• /
• 1987

Lee, Moon Won reported by 63 kinds lescribing the petrography and bulk chemical Composition in Petrology of Cheju volcanic island. The total Chemical Composition data was analyzed by the program of FORTRAN77. First, the Conversition equations and the scatter diagram were examined to the analysis, by the least square method. Next, a statistical data requested a mean Value, maximum value, minimum value, the range, the standard deviation, the variance, the Standord Error and the Coefficient of variation. In the standard deviation, a small Composition is MnO and P$_2$O$\sub$5/, a large Composition is SiO$_2$, Mgo and FeO. The Standard error and the variance were the tandency looked like the Standard deviation well. However, the Coefficient Variation differs from the Standard deviation. Where, a large Coefficient of variation are H$_2$O$\^$-/ and H$_2$O$\^$+/, a small Coefficient of variation are Al$_2$O$_3$ and SiO$_2$. The Correlation of Coefficient Can be Calculated numerically from the relation between SiO$_2$, Al$_2$O$_3$ and TiO$_2$ to other Compositions.

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

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

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.22 no.4
• /
• pp.87-92
• /
• 2014

In spite of ICAO's effort to ensure the safety of flight operation by requiring crews, controllers, and other ground aviation staffs to use unified system for units, SI (System International of units), there are still many aircrafts designed, manufactured, and operated based on non-SI units, and many crew training in airline companies are also conducted based on non-SI. Due to this confusion of using different unit systems in international flight operation, many crew members and passengers are exposed to danger. International flights pilots may have confusion while flying different airspaces of different countries that use different unit systems, and this may cause human errors causing accidents and incidents. Due to these reasons, it is needed to establish the standards to reflect non-SI that many countries practically use to SI, which is international standard.

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

• Nuclear Engineering and Technology
• /
• v.8 no.2
• /
• pp.124-128
• /
• 1976