• Journal of Educational Research in Mathematics
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• v.27 no.4
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• pp.747-764
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• 2017

Problems in mathematics textbooks are very important because there is a high reliance on textbooks in elementary school mathematics classes and there is a strong belief that mathematics is to find the solution to problems. Considering this importance, we analyzed problems in elementary mathematics textbooks quantitatively and qualitatively. Concretely, problems of addition and subtraction with carry on in the range of two digit numbers in the mathematics textbooks from the 1st to the 2015 national revised curriculum were analyzed. As a result, the problems in each textbook were found to reveal important features of the textbook reflecting changes in curriculum and educational background. And the problem of textbooks has changed in the direction of enhancing students' reasoning, communication, and problem solving ability. Based on these results, we suggested several implications for dealing with problems in elementary mathematics textbooks.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.11
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• pp.915-922
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• 1991

This research paper presents an ALU unit using 1.0$\mu$m CMOS technology capable of doing IEEE standard single and double precision floating poing calculation within 32ns (2 clock) at 60 MHz clock speed. This 32ns speed was achieved by using 9ns 1's complement arithmetic 54 bit carry select adder instead of previous 2's complement adders. On the first cycle, this adder is used for addition or subtraction and the second cycle uses this adder for rounding. This reduces the number of required adders from two to one. Speed improvement is 2 to 5 times compared with previous 40MHz design. Design goal was 60MHz, however, this unit is functioning at 80 MHz at room temperature.

• Clinical and Experimental Reproductive Medicine
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• v.29 no.4
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• pp.295-302
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• 2002

Uterine cells carry out proliferation and differentiation for preparation the embryonic implantation during pregnancy. Therefore regulation of the cell proliferation is an essential step for uterine preparation, but there is not much information about the proliferation related genes in pregnant uterus. To identify these implantation specific genes, a PCR-select cDNA subtraction method was employed and got a few genes. One of the identified genes is a novel gene encoding oral tumor suppressor doc-1. To detect the doc-1 expression on the pregnant uterus, dot blotting, RT-PCR, and in situ hybridization were employed. Dot blotting revealed that doc-1 mRNA expression increase after implantation. During normal pregnancy, doc-1 mRNA expression was detected as early as day 1 of pregnancy with RT-PCR. Its expression was increased about 15 times after embryonic implantation. doc-1 transcript was localized in luminal epithelial cells but it was very faint during preimplantation. After starting the implantation, it localized in the stromal cells; heightened expression of doc-1 correlates with intense stromal cell proliferation surrounding the implanting blastocyst on day 6 morning. However in the decidualized cells, the intensity of localized doc-1 mRNA was weak. From those results, it is revealed that doc-1 express at pregnant uterus of the mouse. In addition it is suggested that doc-1 is the gene regulating the proliferation of the luminal epithelial cells and stromal cells during early implantation and decidualization.