• Transactions on Electrical and Electronic Materials
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• v.15 no.6
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• pp.328-332
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• 2014

Thin film transistors (TFTs) with an amorphous silicon zinc tin oxide (a-2SZTO) channel layer have been fabricated using an RF magnetron sputtering system. The effect of the change of excitation electron on the variation of the total interfacial trap states of a-2SZTO systems was investigated depending on sputtering power, since the interfacial state could be changed by changing sputtering power. It is well known that Si can effectively reduce the generation of the oxygen vacancies. However, The a-2SZTO systems of ZTO doped with 2 wt% Si could be degraded because the Si peripheral electron belonging to a p-orbital affects the amorphous zinc tin oxide (a-ZTO) TFTs of the s-orbital overlap structure. We fabricated amorphous 2 wt% Si-doped ZnSnO (a-2SZTO) TFTs using an RF magnetron sputtering system. The a-2SZTO TFTs show an improvement of the electrical property with increasing power. The a-2SZTO TFTs fabricated at a power of 30 W showed many of the total interfacial trap states. The a-2SZTO TFTs at a power of 30 W showed poor electrical property. However, at 50 W power, the total interfacial trap states showed improvement. In addition, the improved total interfacial states affected the thermal stress of a-2SZTO TFTs. Therefore, a-2SZTO TFTs fabricated at 50 W power showed a relatively small shift of threshold voltage. Similarly, the activation energy of a-2SZTO TFTs fabricated at 50 W power exhibits a relatively large falling rate (0.0475 eV/V) with a relatively high activation energy, which means that the a-2SZTO TFTs fabricated at 50 W power has a relatively lower trap density than other power cases. As a result, the electrical characteristics of a-2SZTO TFTs fabricated at a sputtering power of 50 W are enhanced. The TFTs fabricated by rf sputter should be carefully optimized to provide better stability for a-2SZTO in terms of the sputtering power, which is closely related to the interfacial trap states.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1072-1081
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• 2020

Screening suitable strains with high temperature adaptability is of great importance for reducing the cost of temperature control in microalgae cultivation, especially in summer. To obtain high temperature-tolerant diatoms, water samples were collected in summer from 7 different regions of China across the Northeast, North and East. A total of 731 water samples was collected and from them 131 diatom strains were isolated and identified based on the 18S rRNA sequences. Forty-nine strains out of the 131 diatoms could survive at 30℃, and 6 strains with relatively high biomass and lipid content at high temperature were selected and were found to be able to grow at 35℃. Cyclotella sp. HB162 had the highest dry biomass of 0.46 g/l and relatively high triacylglycerol (TAG) content of 237.4 mg/g dry biomass. The highest TAG content of 246.4 mg/g dry biomass was obtained in Fistulifera sp. HB236, while Nitzschia palea HB170 had high dry biomass (0.33 g/l) but relatively low TAG content (105.9 mg/g dry biomass). N. palea HB170 and Fistulifera sp. HB236 presented relatively stable growth rates and lipid yields under fluctuating temperatures ranging from 28 to 35℃, while Cyclotella HB162 maintained high lipid yield at temperatures below 25℃. The percentage of saturated fatty acids and monounsaturated fatty acids in all the 6 strains was 84-91% in total lipids and 90-94% in TAGs, which makes them the ideal feedstock for biodiesel.

• Resources Recycling
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• v.24 no.3
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• pp.66-75
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• 2015

The flexural performance of amorphous steel fibers having environmental and economy benefits due to relatively short manufacturing process were evaluated as well as that of hooked steel fibers by varing fiber length and volume fraction. Fiber lengths were 10 mm, 20 mm, 30 mm and fiber volume fractions were varied from 0.3% to 1.2%. Test results with flexural performance showed that mixing design needs to be careful because of relatively high volume of amorphous steel fiber compared to hooked steel fibers. High flexural strength was obtained from both longer fiber length and higher volume fraction. Residual strength and toughness of amorphous steel fiber were similar to that of hooked steel fiber, even though rapid dropping of applied load right after concrete matrix breaking. It can be judged that relatively high ability of energy dissipation around first cracking area relatively overcome rapid dropping of loading.

• The Korean Journal of Zoology
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• v.7 no.2
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• pp.41-47
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• 1964

D.auraria is a species belonging to the D.melanogaster group, and this species was divided into 3 races(A, B and C race ) by morphoogical difference of the genitals . Korean populations of D.auraria A race are polymorphic with respect to the pigmentation of the abdominal tergites. The female shows two forms of color pattern, dark and light, on the sixth to the ninth tergites, and the male has no distinction shown by the female. Crossing experiments in the laboratory have shown that the difference between these color forms is due to a single pair of allelic genes located on an autosome. In natural populations, the light forms of females are always commoner than the dark one. The number of the light form increases relatively in southern localities and decreases relatively in northern localities. Furthermore, the number of the light form increases relatively in summer and decreases relatively in fall and spring. By genetic analyses of these wild flies, the relation, d/d>d/D>D/D has been disclosed as regards the relative frequencies of the genotypes in natural populations. Three experimental populations have been set up in the laboratory. Homozygous dark forms and homozygous light forms were mixed together and cultured in population cage at the temperature of 25 $^{\circ}C$. Approximately one year later, the frequencies of the light and the dark forms reached an equilibrium , the light one being usually more frequent than the dark one. This indicates that the heterozygous dark form possesses the highest adaptive value, the homozygous light being intermediate and the homozygous dark lowest. In number of adults hached, the homozygous light form was superior to the heterozygous dark form and the homozygous dark form, but the differences are scarcely significant.

• Journal of Korea Water Resources Association
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• v.35 no.5
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• pp.475-484
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• 2002

A series of settling tests and physico-chemical property tests on Saemankeum fine-cohesive sediments has been conducted in order to investigate the correlation between settling properties and their physico-chemical properties which are represented as grain size distribution, mineralogical composition, and percentage of organic contents. Experimental results of physico-chemical property tests show that Saemankeum sediments are relatively large in average grain size(52${\mu}{\textrm}{m}$), and contain very small organic materials(2%), and are dominantly composed of Quarts in mineralogical aspect which has relatively low cohesion. Thus, Saemankeum sediments might be specified as the sediments whose settling properties are more influenced by the gravity than the cohesion. This characteristics of Saemankeum sediments are found to lead to relatively small settling velocity in flocculated settling region in which increasing cohesion results in increasing settling velocity, while relatively large settling velocity in hindered settling region in which settling velocity decreases with increasing cohesion.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.147-163
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• 2000

The mineralogy and chemical composition of reddish to brownish yellow residual soils, so called "Hwangto" have been examined according to representative host rocks. The result of the study indicates that Hwangto consists of 40-80% clay minerals and various minerals such as quartz, feldspar, hornblende, goethite, and gibbsite. Clay minerals include kaolinite, halloysite, illite, hydroxy interlayered vermiculite (HIV), mica/vermiculite interstratifield mineral and chlorite. The mineralogical constituents and contents of Hwangto were different depending on the types of host rocks. Moreover, the Jurassic granitic rocks contain relatively more kaolin minerals, whereas the Cretaceous granitic rocks contain more HIV and illite. In addition, reddish Hwangto contains relatively more kaolinite and HIV, and yellowish Hwangto contains more illite and halloysite. It is suggested that feldspars and micas of host rocks were chemically weathered into illite, halloysite, illite/vermiculite interstratified minerals, and HIV, and finally into kaolinite. Compared with their host rocks, the major chemical compositions of Hwangto tend to contain more $Al_2O_3,\;Fe_2O_3,\;H_2O$ in amount and less Ca, Mg, and Na. Hwangto contains relatively high amount of trace elements, P, S, Zr, Sr, Ba, Rb, and Ce including considerable amount of Li, V, Cr, Zn, Co, Ni, Cu, Y, Nb, La, Nd, Pb, Th in excess of 10 ppm. Relatively high amount of most trace elements were detected in the Hwangto. The major and minor chemical compositions of the Hwangto were different depending on the types of host rocks. However, their difference was in the similar range compared with the compositions of host rocks.

• Journal of Engineering Education Research
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• v.23 no.1
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• pp.10-25
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• 2020

This study was conducted to identify the causes of academic weakness and to find the ways to cope with it for the students majoring in science and engineering at the top university in Korea. For this purpose, a questionnaire was conducted for students who experienced academic warning and poor academic performance at A university, and a total of 207 students responded. The results were divided into two groups majoring in science and engineering or not and the characteristics and differences of each group were analyzed. In addition, in-depth interviews were conducted with five students who had experienced academic warning and poor academic performance. As a result, the group majoring in science and engineering had a relatively low level of difficulty in forming interpersonal relationships and relatively high degree of participation of activities in their departments. The group majoring in science and engineering have a tendency to choose careers that are connected with their majors, and therefore, their response was relatively low due to lack of career goals. However, the group majoring in science and engineering had difficulty in academic performance due to the difference in basic courses and the level of recognition about self-learning strategy needed for university study was relatively low compared with the group majoring in non-science and engineering. When they experienced academic problems, they said that their interest, support, and positive feedback from professors helped them recover their motivation and continue their studies. Through these results, it was confirmed that intervention and support are needed considering the academic situation and characteristics of the students majoring in science and engineering.

• The Journal of Korean Obstetrics and Gynecology
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• v.20 no.1
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• pp.169-185
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• 2007

Purpose : The purpose of this study was to investigate menstrual symptoms and patterns of high school girls by Sasang constitution and relationship between such symptoms and Sasang constitution. Methods : For the study, QSCCII and 'M.B.Q' employed to analyze the data collected from 581 high school girls in Pusan from July 11 to July 20, 2006. Results : As for menstrual characteristics of the subjects by Sasang constitution Taeeumins start menarche is relatively early in contrast with Soeumins who experienced menarche relatively late(P=.012). This survey proves that menses last relatively long for Soeumin whereas Soyangins have relatively short period of menstruation(P=.043). Furthermore, Taeeumins account for majority of those who have much quantity of menstruation with 22.7% while Soeumins account for majority with 13.2%. From the analysis into menstrual symptoms of the subjects put under 5 categories of Sasang constitution, it became evident that Soeumins turned out to have most negative affect(11.8${\pm}$3.78) (P=.053). Soeumins scored the highest points in the response area of autonomic reactions(10.6${\pm}$3.24)(P=.014). In the total points of menstrual symptoms including the above 5 sub-categories, Soeumins recorded the highest scores(52.4${\pm}$12.5), followed by Soyangins(50.0${\pm}$12.2) and Taeeumins in order, showing that there is no statistically significant difference(F = 2.859, p = .058) among them although Soeumins seem to feel slightly more menstrual symptoms than Soyangins and Taeeumins. Conclusion : We hope these results could be helpful to diagnosis and treatment of mestrual diseases.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.182-188
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• 2012

In this study we analyzed carbon emissions of leaves of a Pinus densiflora which is vulnerable to a forest fire using the cone calorimeter in order to analyze greenhouse gas emissions from forest fires depending on region and altitude. Fuels were collected from 9 regions[Hongcheon(Gangwon-do), Chungsong(Gyeongbuk-do), Yanhpyeong (Gyeonggi-do), Jecheon(Chungchongbuk-do), Gongju(Chungcheongnam-do), Wuju(Jeollabuk-do), Youngam(Jeollanam-do), Busan and Jeju-do)] and 9 altitudes(80 m, 450 m, 900 m, 1000 m, 1100 m, 1200 m, 1300 m, 1400 m and 1500 m) and then, carbon dioxide and carbon monoxide emissions contained in a weight of 50 g of fuel were analyzed. According to the results, there were differences in carbon emissions by regional groups, as the average carbon dioxide and carbon monoxide emissions in 9 regions were nearly 43.5929 g to 52.8868 g, and 0.8842 g to 3.6422 g, respectively. Busan and Jecheon had relatively higher carbon dioxide emissions and especially, Busan had 1.23 times higher carbon dioxide emissions than Jeju-do. Also, Gongju, Chungcheongnamo Province and Busan had relatively higher carbon monoxide emissions and especially, Gongju and Pusan had relatively higher carbon monoxide emissions and especially, Gongju had 4.12 higher carbon monoxide emissions than Hongcheon. In addition, there were differences in carbon emissions too depending on altitude, since carbon dioxide and carbon monoxide emissions in 9 altitudes were respectively, 40.7015 g to 68.9297 g and 1.3923 g to 12.2918 g. At the altitude of 80m, carbon dioxide and carbon monoxide emissions were respectively, 68.9297 g and 12.2918 g, and at the altitude of 450m, carbon dioxide and carbon monoxide emissions were respectively, 65.5115 g and 11.2497 g. These results show that pine trees at the lower altitude discharge relatively more carbon. It is considered that this analysis on carbon emissions depending on region and altitude can be effectively used for predicting greenhouse gas emissions and establishing statistical data from forest fires in each region and altitude.

• Journal of Environmental Science International
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• v.24 no.8
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• pp.969-980
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• 2015

In order to certificate the distribution and pollution of heavy metal of surface sediments in Nakdong River were collected and analyzed for grain size, water content, ignition loss and heavy metal content. Surface sediments mainly composed of sand(avg. 94.6%) and water content and ignition loss were 20.46%, 1.53% on average. Grain size were relatively fine and organic matter content were relatively high in the Hoichun and Sunakdonggang. Most of heavy metal content(Zn > Cr > Pb > Ni > Cu > Hg) in the Deokcheongang and Sunakdonggang were higher than the other streams. The Igeo were non polluted(less than 0) in all streams and the EF were relatively high in the small stream and PLI were non polluted(less than 1). In addition, organic matter, heavy metal content and pollution were highly correlation with grain size. Surface sediments in study area, heavy metal pollution of the Sunakdonggang were relatively high compared to the other stream but these results were not serious pollution that exceed the sediment pollution evaluation standard of river and lake in Korea and pollution levels adversely affected the majority of benthos were not.