• Journal of Korean Elementary Science Education
• /
• v.27 no.3
• /
• pp.287-295
• /
• 2008

Elementary students' behaviors classifying leaves have been analyzed according to the material types provided for the classification class. 199 sixth grade students were participated in the task classifying the leaves of various plants for the research. The three types of materials provided to them for the class were real leaves, photos of the leaves and explanation cards including the photos of leaves. One of the research findings was that the only material made students handle in the observed behaviors was the real leave of the material types given as classifying. Three were differences between groups in the time required and the number of using criteria for the class. The numbers of criteria had been applied to analyzing their behaviors as classifying the real leaves which were less than those with photo materials. The amount of taken time to classify the real leaves and photo materials were less than those of another material. Finally, the contents of criteria did not differ between groups except appearing properties presented to the task with photo and explanation materials. It is expected that the research can be contributed for elementary school teachers and for curriculum developers to choose appropriate instructional materials as constructing curriculum contents for elementary science to make elementary school students acquire classifying skill in science classes.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2424-2429
• /
• 2003

The importance of e-Learning, which supports to study anywhere and anytime, has been pointed out for improving education. There have been various research papers on e-Learning system for educations. Most of literatures have focused on guiding the student or measuring understanding their level etc. Design method of e-Learning system has not been discussed based on structure and analysis of the class. In this paper, scheme of the class is proposed by analyzing and structuring class, then design method of e-Learning system is discussed based on it.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.239-242
• /
• 2009

$Sr_2Si_5N_8:Eu^{2+}$, one of the most recently developed phosphors for use in white light emitting diodes, exhibits a two-peak emission. Namely, the emission band of $Sr_2Si_5N_8:Eu^{2+}$ is deconvoluted into two Gaussian peaks irrespective of the $Eu^{2+}$ concentration. We examined the two-peak emission of $Sr_2Si_5N_8:Eu^{2+}$ by analyzing the time-resolved photoluminescence spectra. We revealed that the two-peak emission was closely associated with the energy transfer taking place between $Eu^{2+}$ activators located at two different crystallographic sites in the $Sr_2Si_5N_8$ structure. The experimental results coincided well with the rate equation model involving the crystallographic information of the host.

• Journal of Applied and Pure Mathematics
• /
• v.4 no.1_2
• /
• pp.27-36
• /
• 2022

An innovation diffusion model is proposed model consists of three classes, namely, a non-adopter class, adopter class innovation-I, and adopter class innovation-II in a partially competitive and cooperative market. The proposed model is analyzed with the help of the qualitative theory of a system of ordinary differential equations. Basic influence numbers associated with first and second innovation $R_{0_1}$ and $R_{0_2}$ respectively in the absence of each other are quantified. Then the overall basic influence number (R₀) of the system is assessed for analyzing stability in the market in different situations. Sensitivity analysis of basic influence numbers associated with first and second innovation in the absence of each other is carried out. Numerical simulation supports our analytical findings.

• Journal of Species Research
• /
• v.12 no.spc2
• /
• pp.1-6
• /
• 2023

During an investigation into the indigenous prokaryotic species diversity in Korea, a total of five bacterial strains were isolated from various environments in Korea. The isolated bacterial strains were identified by analyzing their 16S rRNA gene sequences, and those with a minimum of 98.7% sequence similarity with known bacterial species but not reported in Korea were designated as unrecorded species. These isolates were assigned to three phyla, five orders, five families, and five different genera. The isolates were identified as Cumulibacter manganitolerans (99.1%) and Myolicibacterium tusciae (98.7%) of the class Actinomycetes; Bacillus marasmi (99.9%) of the class Bacilli; and Novosphingobium mathurense (100%) and Microvirga ossetica (98.8%) of the class Alphaproteobacteria. Gram reaction, colony and cellular morphology, basic biochemical characteristics, and phylogenetic position of theses isolates are also described.

• Journal of The Korean Association For Science Education
• /
• v.40 no.6
• /
• pp.595-609
• /
• 2020

The purpose of this study is to analyze the experiences of teachers who participated in the development of online science class videos in the context of covid-19, their perception of online science class, and the characteristics of the online science class content developed by teachers. A survey and interviews were conducted with ten elementary school teachers who made online science class videos themselves. Also the characteristics of the online science class were investigated by analyzing the online science class video produced by the participants. As a result, participants in the study recognized the lack of production time, difficulty in filming and editing, concerns over misconceptions, the problem of solving copyrights for existing materials, and the burden of external disclosure. Although it was a teacher who had experience producing online science class video contents, no research participants actively answered the merits of online science class. On the other hand, the study participants cited that the shortcomings of online science classes were that students had fewer opportunities for inquiry and lack of communication or interaction. In particular, these shortcomings were thought to have a great influence on the quality of online science classes, especially in making inquiry classes difficult. Some teachers took a negative view that online science classes could not completely replace face-to-face classes. However, if multiple teachers are presented with supplementary teaching activities that complement the content-based online teaching method, the method of combining online science classes and face-to-face classes is not. Through the analysis of the contents of the online science class, the introduction and arrangement steps of the online science class were similar to the process of the face-to-face science class, but the inquiry step and the conceptual explanation step showed a big difference from the face-to-face science class.

• Journal of The Korean Association For Science Education
• /
• v.26 no.1
• /
• pp.9-15
• /
• 2006

Students have often experienced difficulties in understanding the concept of the particulate nature of matter despite its importance in chemistry. Although various instructional methods have been suggested for teaching this concept, systematic studies have been rarely conducted. Therefore, this study investigated the effects of drawing and analyzing pictures. Three classes of 7th graders at a coed middle school in Seoul were assigned to the control group, the drawing group, and the analyzing group, respectively. Students were taught about the three states of matter and the motion of molecules for 8 class periods. The instructional effects on student conception, achievement, and science learning motivation were investigated by student visual learning styles. Results revealed that the scores of a conceptions test and a science learning motivation test for both the drawing group and the analyzing group were higher than those for the control group. Additionally, the scores of the science learning motivation test were also found to be higher for students with a more visual learning style than their counterparts.

• The Journal of the Korea Contents Association
• /
• v.16 no.11
• /
• pp.594-604
• /
• 2016

This study was performed by targeting nurses majoring in nursing science of Korea National Open University in order to examine the level of their class satisfaction, academic self-efficacy and self-directed learning ability and to identify their effects on self-directed learning ability. Data was collected by targeting 231 nurses majoring in nursing science of Korea National Open University and for data analysis, technical statistics, correlation analysis and multiple regression analysis were performed through statistical analysis program. This study revealed that there was significant correlation among the levels of participants' class satisfaction, self-directed learning ability and academic self-efficacy and it was identified that class satisfaction and self-directed learning ability affected academic self-efficacy. The findings of this study could be utilized as base data when developing a program to enhance nursing student's self-directed learning ability and it is suggested that an interventional research of analyzing validity and effectiveness of developed education program would be also required.

• BMB Reports
• /
• v.32 no.6
• /
• pp.541-546
• /
• 1999

When we compared the chitinase activity of various plant sources using colorimetric or active gel-staining assay methods, the specific activity of pumpkin leaves was the highest among the samples we analyzed. The highly active chitinase from pumpkin leaves (designated PL-ChtIII) was purified to homogeneity using affinity chitin gel and HPLC Mono-Q anion-exchange cloumn chromatographies. In contrast to other members of the class III chitinase family, PL-ChtIII showed a strong binding affinity to the regenerated chitin gel column. The apparent molecular weight of PL-ChtIII was estimated to be 29 kDa on SDS-PAGE gel, while its optimum pH and temperature were shown to be pH 6.0 and $60^{\circ}C$, respectively. Analyzing the reaction products of PL-ChtIII with swollen chitin as substrate, the dimer and tetramer of N-acetylglucosamine were produced as major products in the first hour of the enzymatic reaction along with a small amount of monomers and trimers. As the reaction time increased, dimeric N-acetylglucosamine became the predominant form of reaction product.

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.9
• /
• pp.895-902
• /
• 2015

In this paper, finite element analysis of a cycloidal pitch reducer for a 2 MW-class wind turbine is reviewed. The system is composed of one cycloid set, one spur gear set, an input shaft, an output shaft, and a housing. The system was also evaluated for stability by analyzing spur gear strength according to ISO 6336. An analysis of the natural vibration characteristics of the 2 MW-class wind turbine cycloid pitch reducer was performed with attention to critical speed with input mass unbalance, output mass unbalance, spur gear transmission error, cycloid gear transmission error, and excitation frequency.