• Journal of the Korean Chemical Society
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• v.47 no.1
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• pp.72-78
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• 2003

In this study, the effects of grouping by extraversion and introversion in POE learning applied to elementary science class on students' achievement, the perception of learning environment and the attitude toward science instruction were investigated. Ninety-five 5th graders were assigned to the control group and the experimental groups, and taught about acid and base for 9 class hours. In the experimental groups, the homogeneous small group was composed of four introverts or four extroverts, and the heterogeneous small group was composed of two introverts and two extroverts. Two-way ANCOVA results revealed that the homogeneous group performed better than the control group in the application subtest of the achievement test. Significant difference in learning difficulty was found between the heterogeneous group and the control group. In the attitude toward science class, significant interaction effect was found between the instruction and the extraversion/introversion.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.453-460
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• 2011

Recently, there is growing interests in the application of supercritical fluids for food and medical fields since supercritical fluids ($CO_2$ and $N_2O$) have known to be safe and effective as a non-thermal sterilization technique. Although supercritical fluids have been investigated for various kinds of products, they have not yet been used in common currency due to their lack of knowledge related to the antimicrobial activity or detailed mechanisms. In this review paper, we summarized the characteristics, antimicrobial activity and mechanisms, important factors, and applicability of supercritical fluids to help the investigation and commercialization of supercritical fluids sterilization technique.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.376-388
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• 2023

After a longitudinal analysis of the data on the college entrance examination of students enrolled in the Department of Chemistry Education at Gyeongnam from 2014 to 2021, the effect on the academic achievement of general chemistry according to the type of college entrance examination was studied. And the impact on the academic achievement of general chemistry according to the type of admission screening in face-to-face and non-face-to-face teaching-learning was also studied. As a result of analyzing the academic achievement of general chemistry by admission process, students admitted through occasional screening showed relatively high grades of A and B at 88.7%, and the ratio of grades of 1~3 of chemistry I in high school was high. On the other hand, in the case of students admitted through regular admission, the ratio of grades of A and B in general chemistry was very high at 94.3%, and the ratio of grades of 3~4 in chemistry I of the College Scholastic Ability Test was high. As a result of analyzing the academic achievement of general chemistry by class type and admission process, it was found that the grades of chemistry I by face-to-face classes had an effect on the academic achievement of general chemistry in non-face-to-face classes. In both admissions, the academic achievement of general chemistry by face-to-face classes was relatively higher than that of non-face-to-face-to-face classes.

• Journal of the Korean Magnetic Resonance Society
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• v.18 no.2
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• pp.52-57
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• 2014

The TCP domain is a DNA-binding domain present in plant transcription factors and plays important roles in various biological functions. The hydrogen exchange rate constants of the imino protons were determined for the three DNA duplexes containing the DNA-binding sites for the TCP11, TCP15, and TCP20 transcription factors using NMR spectroscopy. The M11 duplex displays unique hydrogen exchange property of the five base pairs in the first binding site (5'-GTGGG-3'). However, the M15 and M20 duplexes lead to clear changes in thermal stabilities of these five base pairs. The unique dynamic features of the five base pairs in the first binding site might play crucial roles in the sequence-specific DNA binding of the class I TCP transcription factors.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.49-52
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• 2009

Single-drop microextraction (SDME) is an extraction methodology where the drop plays an essential role as extracts. It was evaluated for the GC-MS determination of nerve agents, one class of the chemical warfare agents (CWAs). Since these nerve agents are highly toxic, it is important to detect the nerve agents in the environmental samples. Several affecting factors including extraction solvents, stirring rate, extraction time, and amounts of salt were optimized. The limit of detections (LODs) were 0.1 - 10 ng/mL and the relative standard deviations (RSDs%, n=5) were in the range of 6.3% to 9.0% for four nerve agents. Without pretreatment of the environmental samples, 5-103 fold enrichments and 48-100% recovery were accomplished. These results demonstrated the feasibility of this method for on-site and off-site analysis of water sample collected from suspicious CWAs site.

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.487-500
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• 1998

A bird's-eye view on preparation, structure and properties of polymeric complexes in the field of Inorganic-Organic-Hybrids is presented in the view point of solid state and materials chemistry. These materials are useful precursors for preparing nanoparticles and fine grain oxides. Some of them are electroactive and are used as protonic or lithium electrolytes, electrochromic materials or membranes for sensors and actuators. New results on bio-hybrids, a class of material not far from polymeric complexes, are also described.

• Mass Spectrometry Letters
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• v.13 no.4
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• pp.125-132
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• 2022

There are many types of spring blossoms on the Daedeok campus of Chungnam National University (CNU) at the area of 1,600,000 square meters. As an assignment for the class of Analytical Chemistry I for second-year undergraduate students, 2021, flower petals collected from various floral groups (Korean azalea, Korean forsythia, Dilatata lilac, Lilytree, Lily magnolia, and Prunus yedoensis) were analyzed using headspace extraction coupled to gas chromatography-mass spectrometry (HS-GC-MS) to study the aromatic profiles and fragrance compounds of each sample group. Various types of compounds associated with the aroma profiles were detected, including saturated alcohols and aldehydes (ethanol, 1-hexanol, and nonanal), terpenes (limonene, pinene, and ocimene), and aromatic compounds (benzyl alcohol, benzaldehyde). The different contribution of these compounds for each floral type was visualized using statistical tools and classification models based on principal component analysis with high reliability (R² = 0.824, Q² = 0.616). These results showed that HS-GC-MS with statistical analysis is a powerful method to characterize the volatile aromatic profile of biological specimens.

• Journal of the Korean Chemical Society
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• v.64 no.5
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• pp.277-290
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• 2020

In this study, four gifted students in the second year of middle school at Gifted Education Center of the National University in Jeollanam-do were surveyed students' perceptions of the effectiveness of science class using science writing heuristic in terms of metacognition and the goals of the 2015 revised science curriculum. Through questionnaires and interviews with gifted science students, science gifted students recognized that the science class using science writing heuristic had a positive effect on the four subdomains (planning, monitoring, control, and evaluation) of metacognition. For this reason, the science gifted students presented self-directed experience in designing experiments, continually checking the collected experimental data, feedback process, and reflecting experience in preparing conclusions. Science gifted students recognized that science class using science writing heuristic had a positive effect on the goals of the 2015 revised science curriculum(attitudes, inquiry, knowledge, Science·Technology·Society(STS), and the enjoyment and usefulness of science learning) that correspond to through inquiry science writing lessons. For this reason, the science gifted students presented self-directed inquiry experiences, continual inquiry experiences on the same subject, thinking process at each stage of inquiry, learning experiences through inquiry, experience of the whole inquiry process, and inquiry of phenomena closely related to real life. Therefore, for the effective science class, it is necessary to apply the characteristics of science class using science writing heuristic which is responded by science gifted students to general science class as well as science gifted class later.

• Journal of The Korean Association For Science Education
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• v.30 no.4
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• pp.519-531
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• 2010

In this study, we investigated the elementary school students' images of science class and the factors influencing their formations. 280 sixth graders were selected from nine elementary schools in Gyeonggi province and Gangwon province and the DASCT-C (Draw-A-Science-Class-Test Checklist) was administered. In addition, four students were individually interviewed in order to investigate their responses deeply. Analyses of the results revealed that the students' images of science class for four science subjects (physics, chemistry, biology, and earth science) were more 'student-centered' than 'teacher-centered' or 'neutral'. The students of the teacher with student-centered image of science class had also more student-centered images than those with teacher-centered images. Many students answered that the main factors affecting their images of science class were the experiences of impressed or funny science classes, the perceptions of wanted science classes, the active science learning experiences, the educational experiences outside the school curriculum, and the negative science learning experiences. Educational implications of these findings are discussed.

• Bulletin of the Korean Chemical Society
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• v.15 no.7
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• pp.534-537
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• 1994

A new metabolite 2 of bastadin class and the previously reported bastadins 3 and 4 were isolated from the sponge Ianthella basta collected in Indonesia.