• Journal of The Korean Association For Science Education
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• v.31 no.6
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• pp.836-847
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• 2011

This study investigated the effects of taking elective science courses in high school on studying science at the university level. The research methods undertaken for this study included surveys of college students in science areas. For physics and biology major students, no significant differences in achievement in the basic courses at the university level were found between the groups that took only Science I courses and the group took Science I and II courses. For chemistry major students, achievement for the group that took Chemistry I and II courses was significantly higher in the basic courses, while no significant differences between the two groups was found in the advanced courses. The perceptions of college students regarding the effects of their science learning experience in high school on learning science at the university level were investigated. All the college students perceived that whether or not they took Science II courses in high school, it did not affect their learning in basic science courses in college. They also perceived that students were able to overcome difficulties by making extra effort even if they did not take Science II courses in high school.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.97-106
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• 2016

This study is to find the converging effects of the Complete Sciences Subjects(CSS) in high school before entrance to University on the scores of Basic Nursing Sciences(BNS) and Major Nursing Subjects(MNS) of 111 senior nursing students of one university. Using the SPSS 19.0, t-test, Pearson's correlation coefficient, multiple and simple linear regression were carried out. The mean scores of the groups that have completed the subjects of Biology I & II, Chemistry I & II were high on Anatomy, Physiology and Pathology. There was a significant difference between the group of completed Biology II and incompleted Biology II on the mean scores of MNS(p<.05). There were positive correlations between the CSS and the scores of BNS and MNS, a moderate correlation between Chemistry II and BNS(r=.303) and a strong correlation between BNS and MNS(r=.796). Explanation rate of CSS on the scores of BNS, and MNS were 18.2%, 8.2% respectively, and on the scores of BNS on MNS was 63.8%. The result of this study can be used in assessing university entrance procedure after repeated study, extended location and more participants, and to use for making pre-school program for the freshmen who didn't CSS.

• Journal of the Korean Chemical Society
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• v.53 no.6
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• pp.793-804
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• 2009

In this study, high school students' perceptions of chemically ill-defined ‘heavy metals’ were examined through questionnaires. Nineteen classes of 11th graders (N = 611) were divided into two groups according to completion of 'Chemistry I', which were 10 science-classes and 9 liberal art-classes and compared each other. Three terms of students' cognition and definition, impact on the formation of their cognition, and their chemical knowledge of 'heavy metals' were analyzed by SPSS. The findings revealed that most of students recognized ‘the heavy metal’ as the metal which causes to be accumulated on any living thing and is hazardous in human body regardless of different major between liberal art and science. Mass media and school instruction were found to be the greatest impact on the formation of these cognitions. Especially, school instruction had more effects on students majoring in science than students majoring in liberal art, which bring the result that students in science-classes have more misconception about the definition of 'heavy metals' with human toxicant regardless of metal species and its content in human body and physical density due to the ill-defined terminology of the textbook than students in liberal art-classes do. It is interesting that students in science-classes understood hazard and chemical structure of 'heavy metals' better, while students in liberal art-classes answered the question better about hazardous properties of heavy metals.

• Journal of Gifted/Talented Education
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• v.26 no.2
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• pp.405-421
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• 2016

The purpose of this study was to investigate students' perception of Advanced Placement Program. Participations of this study were 1144 students from 14 science high schools. The results showed as follows. First, students perceived positively regarding AP program and were willing to take AP courses because of interesting and challenging in academic area which is provided by AP courses. Secondly, many students would like to take AP courses in Differential and Integral Calculus 1, General Physics I, General Chemistry I and General Biology. Also, they would like to take AP courses in first term as a mandatory subjects. Third, responses perceived that AP courses were challenging, difficult, and of high quality. Finally, students perceived the benefit of AP courses in earing college credit. However, 35% of responses wished to receive an exemption for all AP courses. Also, they wished to have dual-major or participate in students exchange program as a benefit of AP program. Implications of the study were discussed in depth based on the results.

• Journal of Science Education
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• v.43 no.2
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• pp.195-206
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• 2019

The study aims to find a way to guarantee high school students choose science subjects by exploring its necessity as a prerequisite for admission to university science and engineering major courses. For this purpose, a survey was administered to 516 science & engineering college students to investigate their cognition and completion of the prerequisite science subjects related to their major, department adjustment, and influence on their major of study. Among nine major clusters, Physics was identified as a science domain with a high relevance to majors in five major clusters, and Chemistry in three. The students who completed both science I and II subjects related to their majors responded most positively to the usefulness of prerequisite subjects to their studies. Suggestions include conditions for the opening of science II subjects, strengthening the connection between science subjects and IT, promotion of linkage between the prerequisite subject and major studies to assert students' choice of science subjects in high school.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.679-695
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• 1998

A series of ${\alpha}{\omega}-bis[4-(4'-(S)-(+)-2-methylbutylbiphenyl-4-carboxy)phenoxy]alkanes$, were synthesized, and their thermal and liquid crystalline properties were studied. The chain length of the central polymethylene spacers, x, of the chiral twin compounds was varied from 3 to 12. These compounds were characterized by elemental analysis, IR and NMR spectroscopy, differential thermal analysis (DSC), and crosspolarized microscopy. All compounds were found to be enantiotropic liquid crystalline, and the values of melting $(T_m)$ and isotropization temperature $(T_i)$ as well as ${\delta}H_I$ and ${\delta}S_I$ decreased in a zig-zag fashion, revealing the so called odd-even effect as x increased. Their mesomorphic properties fell into four categories depending upon x; (a) compounds with x=3, 4 and 5 formed only a cholesteric phase on heating, while on cooling they went through two transitions of isotropic (I)-to-cholesteric (Ch) and Ch-to-smectic $A\;(S_A)$ phases before crystallization. (b) compounds with x=6, 8 and 10 exhibited only a cholesteric phase both on heating and on cooling. (c) compounds with x=7 and 9 went through three transitions of crystal $(C)-to-S_A,\;S_A-to-Ch,$ and Ch-to-I phases on heating while on cooling they went through four transitions of I-to-Ch, $Ch-to-S_A,\;S_A-to-Smectic\;C\;(S_C),\;and\;S_c-to-C$ phases in that order, and (d) compounds with x=11 and 12 went reversibly through four transitions of $C-to-S_C,\;S_C-to-S_A,\;S_A-to-Ch,$ and Ch-to-I phases.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.67-72
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• 2008

We have studied the effect of heat treatment of multi-walled carbon nanotubes (MWNTs) as a counter electrode on the electro-chemical properties of dye-snsitized solar cells. MWNTs on the p-type Si substrate were synthesized by thermal chemical vapor deposition (CVD) using Fe catalysts. We prepared the two types of MWNTs samples with the different diameters. The rapid thermal annealing (RTA) treatment for the MWNTs was carried out at the growth temperature ($900^{\circ}C$) for 1 minute with $N_2$ gas atmosphere. The structural, electrical and electrochemical properties of MWNTs were investigated by field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, 2-point probe station and electrochemical impedance spectroscopy (EIS). The I(D)/I(G) ratio of heat-treated MWNTs in Raman spectra was considerably decreased. It was also found that the heat-treated MWNTs showed better redox reaction of iodide at the interface between MWNTs surface and electrolyte than that of as-grown MWNTs. The redox resistance value of heat-treated electrodes was measured to be much lower than that of as-grown electrode at the interface. As a result, the counter electrode using the heat-treated MWNTs showed better electrochemical properties.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.127-137
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• 2000

Eleven new compounds that are composed of bis(p-substituted phenyl) terephthalate unitand the decyloxy pendant as lateral were synthesized and their thermal and liquid crystalline properties were studied by the differential scanning calorimetry (DSC) and on a hot-stage of a polarizing microscope. The ter-minal substituent groups of the compound were varied; X= -H(II-H), -F(lI-F), -CII(II-CI), -Br(ll-Br), -I(II-I), -$NO_2(lI-NO_2$), $-CF_3(II-CF_3$), -$OC_2H_5(II-OC_2H_5$), -$OC_4H_9(II-OC_4H_9$), -$C_6H_5(Il-C_6H_5$). The compounds of $II-OC_2H_5,\;II-OC_4H_9$ and $II-C_6H_5$ were monotropically nematic. In contrast, the compounds of Il-H, II-F, II-Cl, II-Br, II-I, $lI-NO_2$, $II-CF_3$, and II-CN did not show liquid crystalline properties.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.616-616
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• 2013

그래핀(Graphene)은 열전도도가 높고 전자 이동도(200,000 cm2V-1s-1)가 우수한 전기적 특성을 가지고 있어 전계 효과 트랜지스터(Field effect transistor; FET), 유기 전자 소자(Organic electronic device)와 광전자 소자(Optoelectronic device) 같은 반도체 소자에 응용 가능하다. 최근에는 아크 방출(Arc discharge method), 화학적 기상 증착법(Chemical vapor deposition; CVD), 이온-조사법(Ionirradiation)등을 이용한 이종원자(Hetero atom)도핑과 화학적 처리를 이용한 기능화(Functionalization)등의 방법으로 그래핀의 전도도를 향상시킬 수 있었다. 그러나 이러한 방법들은 기판의 표면을 거칠게 하며, 그래핀에 많은 결함들이 발생한다는 단점이 있다. 이러한 단점을 극복하기 위해 자가조립 단층막법(Self-assembled monolayers; SAMs)을 이용하여 기판을 기능화한 후 그 위에 그래핀을 전사하면, 자가조립 단층막의 기능기에 따라 그래핀의 일함수를 조절 가능하고 운반자 농도나 도핑 유형을 변화시켜 소자의 전기적 특성을 최적화 할 수 있다 [1-3]. 본 연구에서는 PET(polyethylene terephthalate) 기판에 SAMs를 이용하여 유연하고 투명한 그래핀 전극을 제작하였다. 산소 플라즈마와 3-Aminopropyltriethoxysilane (APTES)를 이용하여 PET 기판 표면 위에 하이드록실 기(Hydroxyl group; -OH)와 아민 기(Amine group; -NH2)를 순차적으로 기능화 하였고, 그 위에 화학적 기상 증착법을 이용하여 합성한 대면적의 균일한 그래핀을 전사하였다. PET 기판 위에 NH2 그룹이 존재하는 것을 접촉각 측정(Contact angle measurement)과 X-선 광전자 분광법(Xray photoelectron spectroscopy: XPS)을 통해 확인하였으며, NH2그룹에 의해 그래핀에 도핑 효과가 나타난 것을 라만 분광법(Raman spectroscopy)과 전류-전압 특성곡선(I-V characteristic curve)을 이용하여 확인하였다. 본 연구 결과는 유연하고 투명한 기판 위에 안정적이면서 패턴이 가능하기 때문에 그래핀을 기반으로 하는 반도체 소자에 적용 가능할 것이라 예상된다.

• Journal of The Korean Association For Science Education
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• v.40 no.2
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• pp.217-226
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• 2020

The purpose of this research is to draw suggestions on the settling of the 2015 revised curriculum and the direction of science curriculum improvement by identifying the current status of science general elective courses for high school sophomores, and examining teachers' perception. To this end, with 12 city and provincial education offices' cooperation, we analyzed the status of science elective subjects that freshmen took in 2018 by school year, school type and region. In addition, in-depth interviews were conducted with nine science teachers of the focus group to discuss ways to improve curriculum operation and implementation of science general elective courses, and ways to raise the selection rate. The number of science general elective courses for high school students in 12 municipal and provincial education offices was confirmed to be 163,710 for Physics I, 216,754 for Chemistry I, 290,736 for Bioscience I, and 200,861 for Earth Science I. By school type, autonomous high schools have the highest completion rate, while specialized schools and vocational schools have very low rates. Units completed per semester for general elective courses were mostly three units (61.5%) and two units (28.7%). High school science teachers suggested reconstruction of three-unit elective courses that can be completed in one semester, content development focused on competences rather than knowledge, and the need for a teacher community to improve teachers' teaching competences. Based on the results of the research, ways to operate high school science elective curriculum in preparation for the high school credit system were suggested.