• Economic and Environmental Geology
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• v.36 no.2
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• pp.141-148
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• 2003

We investigated the distribution of sea ice using various microwave remote sensing techniques including radar altimeter, radiometer, and scatterometer data in the part of Drake passage, Antarctica, between the area 45$^{\circ}$-75$^{\circ}$W and 55$^{\circ}$-66$^{\circ}$S. Topex/poseidon radar altimeter data were used to analyze the monthly distribution of sea ice surface area between 1992 and 1999 by using Geo_bad_1 flag or MGDR. From satellite radiometer measurements of DMSP's SSM/I, sea ice concentration was extracted during the period from 1993 to 1996. To select a value of ice concentration, normally ranging from 0 to 100%, that can be used as a critical value of judging the existence for ice, sea ice areas estimated from various ice concentrations of radiometer measurements were correlated with the area estimated from the radar altimeter measurements. As a result, 20% of ice concentration was selected, and, then this value was used to integrate radiometer data with radar altimeter and ERS-1/2 scatterometer data. To indirectly verify the result, the last 20 year's sea ice concentration was correlated with surface temperature data near Esper-anza Observation Station. The two data showed a high correlation coefficient of 0.86. The amount of sea ice and temperature variation were found to be closely related in the study area, and this indirectly verifies the result of this study. We provided a method to judge the existence of sea ice from ice concentration of satellite radiometer data and suggested a method to monitor more detailed temporal and spatial variation of sea ice distribution by integra-tion of various microwave remote sensing techniques.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.1
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• pp.19-25
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• 2002

The objectives of this study were to understand the possible mechanism of duck sperm toxicity induced by arsenic exposure in vivo, and to investigate the roles of the antioxidant L-ascorbic acid in ameliorating the arsenic-induced sperm impairment. To test the acute toxicity, the percentages of mortality of mature drakes treated with different concentrations of trivalent sodium arsenite, As (III), and pentavalent sodium arsenate, As (V) were measured. The LD50 value of As (III) for mature drakes was $4.89{\pm}1.49$ ppm. Although As (V) didn't cause any deaths even at a concentration of 40 ppm, the chronic toxicity of As (V) on sperm quality was shown by a decreased fertilization rate. When the concentrations of As (V) were above 0.4 ppm, fertilization rates were lower than those of 0.04 ppm and control. Drakes treated with 40 ppm of As (V) had the highest malondialdehyde (MDA) level in the testis tissue, $3.100{\pm}0.218{\mu}mole/g$ testis. This showed that 40 ppm of As (V) significantly induced lipid peroxidation in testis tissue. For the 1.2 ppm As (III) treatment, several significant effects were observed: (1) sperm motility was decreased most dramatically by $52.0{\pm}9.1$% after three days of incubation; (2) fertilization rate of artificially inseminated semen was the lowest, $26.4{\pm}15.4$; (3) the MDA concentration in testis tissue, $7.846{\pm}0.246{\mu}mole/g$ testis, was significantly higher than the others (p<0.05); (4) the sperm number, $1.17{\pm}0.40({\times}10^9)$, was significantly lower than with the 60 ppb and control treatments (p<0.05); (5) a black appearance and soft texture was observed in the testis tissue. The antioxidant L-ascorbic acid administered along with 1.2 ppm As (III) decreased the toxicity of arsenic. The ameliorating effects included: improved sperm motility, increased sperm number and fertilization rate, and decreased MDA concentration in the testis tissue. This study suggests that the toxicity of the trivalent arsenic on sperm quality is partly from free radicals generated by its metabolic pathway, and the antioxidant ascorbic acid ameliorates arsenic-caused sperm impairment.

• Journal of the Mineralogical Society of Korea
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• v.19 no.3 s.49
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• pp.163-169
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• 2006

Mineralogy and geochemistry of the sediment core from the seamount (2710 m below the sea level) just south of the Antarctic Polar Front were examined to draw paleoceanographic information in glacial-interglacial cycles. Smectite was most abundant clay mineral associated with illite and chlorite. Its content was slightly higher below 170 cm, suggesting a boundary between isotope stage 4 and 5. Si, Zr, Cs, Th, REE, $K_{2}O$, and $Al_{2}O_{3}$ show complete antithetical distribution with respect to $CaCO_{3}$ through the core. $SiO_{2}$ maxima and $CaCO_{3}$ minima at depths of 24, 136, and 176 cm are probably correlated with massive influx of ice-rafted debris during the advance of Antarctic ice shelves. Ni, Cu, and Ba show rather little correlation with $SiO_{2}$, suggesting their relation to biogenic debris, precipitation from seawater, or hydrothermal input. Particularly, Ba maxima tend to lag $10{\sim}20cm$ after $SiO_{2}$ maxima, probably due to rapid increase of productivity following deglaciation.

• Journal of Elementary Mathematics Education in Korea
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• v.22 no.3
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• pp.267-282
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• 2018

The purpose of this study is to develop and apply a Convergence program for teaching of congruence and symmetry and to investigate the effects of the mathematical creativity and convergence talent. For these purposes, research questions were set up as follows: 1. How is a Convergence program for teaching of congruence and symmetry developed? 2. How does a Convergence program affect the mathematics creativity and convergence talent of fifth grade student in elementary school? The subjects in this study were 16 students in fifth-grade class in elementary school located in Songpa-gu, Seoul. A Convergence program was developed using the integrated unit design process chose the concept of congruence and symmetryas its topic. The developed program consisted of a total 12 class activities plan, lesson plans for 5 activities. Mathematics creativity test, a test on affective domain related with convergence talent measurement were carried out before and after the application of the developed program so as to analyze the its effects. In addition, students' satisfaction for the developed program was investigated by a questionnaire. The results of this study were as follows: First, A convergence program should be developed using the integrated unit design process to avoid focusing on the content of any one subject area. The program for teaching of congruence and symmetry should be considered students' learning style and their preferences for media. Second, the convergence program improved the students' mathematical creativity and convergence talent. Among the sub-factors of mathematical creativity, originality was especially improved by this program. Students thought that the program is good for their creativity. Plus, this program use two subject class, Math and Art, so student do not think about one subject but focus on topic 'congruence and symmetry'. It help students to develop their convergence talent.

• Journal of Practical Agriculture & Fisheries Research
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• v.8 no.1
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• pp.30-42
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• 2006

This experiment was conducted to investigate current situation and plant grouping by light and watering of mingled several cacti and succulents in a pot. The main 11 cacti are consist of Myrtillocactus geometrizans (Mart.) Cons., Gymnocalycium mihanovichii var. friedrichii Werd., Marginatocereus marginatus(DC.) Backbg., Eriocactus leninghausii (Hge. Jr.) Backbg, Notocactus scopa (Spreng.) Berg., Lobivia nealeana Backbg., Mammillaria elongata var. intertexta (DC.) SD., Pseudoespostoa (Vp1.) Backbg., Mammillaria albilanata Backbg., Mammillaria klissingiana Bod. and Espostoa lanata (HBK.) Br. & R. The main 10 succulents are Kalanchoe thyrsifolia Harv., Portulacaria afra var. foliis-variegatis Jacobs., Crassula perforata Thunbg., Echeveria pulvinata Rose, Aeonium arboreum cv. atropurpureum., Echeveria lauii Moran & J. Meyran, Pachypodium lamerei Drake, Sedum rubrotinctum cv. Aurora Boom., Aloe mitriformis Mill., and Euphorbia coerulescens Haw. The cacti were native to Mexico, Brazil, Peru, Paraguay, Ecuador, etc. The sucullents were native to Mexico, Africa, Gran Canaria, Madagascar, etc. Most of all the cacti and sucullents in the experiment are growing well under full sun or light shade, however Portulacaria afra var. foliis-variegatis Jacobs, and Sedum rubrotinctum cv. Aurora Boom. did not influenced by light. And all the plants require a little or moderate watering. Thus, planting by similar required water and light, when growing in a pot of several cacti and succulents, might be decreased the rate of death causing by their different plant physiology.

• Korean Journal of Veterinary Research
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• v.23 no.2
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• pp.137-148
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• 1983

This study was made for the better information of the male reproductive system on the meat-type drake, Cherry Belly X White Golden. The epithelium of ductules of epididymal region and deferent duct were observed histologically and histochemically with the progress of their development. India-ink absorbability on the luminal epithelium was also investigated after the administration of India-ink. The results are as follows; 1. Rete testis and various round ductules in immature form appeared in epididymis within 6 weeks after hatching, and simple cuboidal and simple columnar epithelium were found in the epithelia of the ductules within 8 weeks after hatching. Larger ductules were found on epididymal surface which was in the developing stage near to the immature efferent ductule. From 10th to 20th week, various ductules appeared in epididymis, and developing form of efferent ductules were much more increased on epididymal surface. The luminal epithelium of the ductules were composed of ciliated simple columnar and pseudostratified ciliated columnar cells. At the same time, deferent duct appeared. From the 21th week, various ductules in epididymis became abruptly matured. Lumen of rete testis was lined by simple squamous or simple cuboidal epithelium, and that of efferent ductules, having many folds and being larger than any others were lined by pseudostratified ciliated columnar epithelium in which ciliated columnar cells, non-ciliated cells(clear cells) and basal cells were noted. Connecting tubules of star shaped lumen were composed of pseudostratified ciliated columnar epithelium in which ciliated columnar cells, nonciliated cells, and basal cells were observed. The luminal surface of epididymal ducts was smooth and has thick pseudostratified columnar epithelium which was composed of high columnar cells and basal cells. From 26th week after hatching, sperm pooling was started in various ductules. 2. From 4th to 10th week, simple cuboidal epithelium of deferent duct transformed to simple columnar epithelium with the progress of aging. At the basement of epithelium, clear round cells were noted. From 12th to 20th week, high columnar cells with enlongated nucleus were noted on the luminal border of deferent ducts, forming folds of pseuclostratified columnar epithelium. From 20th week, the deferent duct started to have septa in it's lumen and composed mainly of pseudostratified columnar epithelium, and round cells disappeared. From 20th week, the lumen diameter of deferent duct became wider with the progress of aging, but there was no difference among the values of lumen diameter in upper, middle, and lower part of deferent ducts. At 26th week, the pooling period of sperms in deferent ducts, the lumen diameter became rapidly widen, especially in the lower part of deferent ducts. Thickness of muscular layer of ductus deferens showed gradual growth within 24 weeks but did abrupt thickening from 26th week. 3. Saliva resistant PAS granules were dotted on the top of nucleus in efferent ductules epithelium but the amount of the granules were little in the connecting ductules's epithelium. The granules reactive to acid phosphatase were abundant in the some epithelial cells of efferent ductules and connecting ductules, especially above the nucleus of cells. The granules reactive to alkaline phosphatase were noted on the luminal border of efferent ductules. Parts of free border of efferent ductules and middle portion of deferent ducts were stained slightly by alcian blue technique. India ink granules were found mainly in the epithelium of efferent ductules but were few in that of connecting ductules.