• Transactions on Electrical and Electronic Materials
• /
• 제15권6호
• /
• pp.328-332
• /
• 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
• /
• 제30권7호
• /
• pp.1072-1081
• /
• 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.

• 자원리싸이클링
• /
• 제24권3호
• /
• pp.66-75
• /
• 2015

상대적으로 제조공정이 짧아 환경 및 경제적 이점을 갖는 비정질강섬유(AF)를 길이 및 혼입률을 변화하여 휨성능을 평가와 더불어 기존의 일반강섬유(HF)와의 비교분석을 실시하였다. 섬유의 길이는 10 mm, 20 mm, 30 mm, 및 혼입률은 0.3%, 0.6%로 변화를 주어 실험을 진행하였다. 비정질강섬유(AF의 경우 비중은 일반강섬유(HF)와 거의 동일한 값을 가지나 겉보기부피는 약 2배정도 커서 같은 혼입률에서 투입되는 섬유의 개수는 훨씬 증가되어 배합설계에서 주의를 할 필요가 있다. 실험결과 휨강도의 영향은 섬유의 길이 및 혼입률이 증가할수록 강도의 증가를 보였으며, 일반강섬유(HF)보다 크게 나타났다. 특히 최대하중부근에서의 에너지소산능력이 뚜렷하게 증가하여 잔류하중단계에서의 급격한 감소에도 불구하고 일반강섬유(HF)와 거의 유사한 잔류강도 및 에너지소산능력을 보여주었다. 콘크리트 균열 후 파괴진행단계에서는 섬유의 인발저항에 의한 균열진행이 아닌 섬유의 파단에 의한 강도의 급격한 감소를 보여준 것으로 판단된다.

• 한국동물학회지
• /
• 제7권2호
• /
• pp.41-47
• /
• 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.

• 한국수자원학회논문집
• /
• 제35권5호
• /
• pp.475-484
• /
• 2002

새만금 미세점착성 퇴적물의 침강특성을 퇴적물 자체의 물리ㆍ화학적 기본특성과 연계 해석하기 위하여, 퇴적물의 입경분포, 광물질 구성 및 유기물 함량 조사로 구성되는 새만금 퇴적물에 대한 물리ㆍ화학적 특성 조사가 수행되었다. 새만금 퇴적물의 물리ㆍ화학적 특성에 대한 분석 결과, 새만금 퇴적물은 평균입경(52$\mu\textrm{m}$)이 비교적 크고 유기물 함량(2%)이 매우 작으며, 점착력이 비교적 자은 석영이 주된 광물질 구성성분으로 점착력에 의한 침강효과 보다는 중력에 의한 침강효과가 더 큰 퇴적물인 것으로 밝혀졌다. 따라서 이러한 효과로 인하여, 새만금 퇴적물은 응집효과가 침강속도를 증가시키는 응집침강 영역에서 비교적 작은 침강속도를 가지며, 응집효과가 침강속도를 감소시키는 간섭침강 영역에서는 비교적 큰 침강속도를 갖는 것으로 나타났다.

• 한국광물학회지
• /
• 제13권3호
• /
• pp.147-163
• /
• 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.

• 공학교육연구
• /
• 제23권1호
• /
• pp.10-25
• /
• 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.

• 대한한방부인과학회지
• /
• 제20권1호
• /
• pp.169-185
• /
• 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.

• 한국안전학회지
• /
• 제27권3호
• /
• pp.182-188
• /
• 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.

• 한국환경과학회지
• /
• 제24권8호
• /
• pp.969-980
• /
• 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.