• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.53-65
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• 2004

This study aimed to analyze the historical evolution of general ideas concerning the particles that represent matter properties and matter changes divided into physical change and chemical change. In the science historical viewpoint, the general ideas of the base that represent matter properties has been variously revised the 5types. The definition of the matter change have also changed the 3 types. From the analysis of the definitions in secondary school science textbooks and general chemistry textbooks, we found that a lot of confusion of eras in the contents that define the concepts. Sometimes, the definition presented in one textbook was contradictory to the definitions in other textbooks. This tendency has been sustained in the textbooks from the 4th to 7th science curriculum.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.266-280
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• 2000

The purpose of this Study was to explore students' conceptual ecologies in the context of general chemistly learning. This study was implemented in the first semester of 1999 by natural study. We had nine voluntary participants. Data were collected from three semi-constructd interiews, and socio-cultural values. Among three categories, motivationa1 beliefs and socio-cultural values have more effcts rather than epistemology on the context of general chemistry learning, and three typical cases were presented as results of this study. We expect that results of this study will somewhat contribute to establish psychological and socio-cultural context of learning.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.130-133
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• 1991

The distribution of acid producing bacteria and general bacteria in 23 samples of Korean traditional Meju loaves was investigated and the strains isolated from the samples identified. The acid producing bacteria occurred more in outer part than inner part and anaerobic acid producing bacteria showed higher tendency of occurrence compared with the aerobes in each part. The average number of nonhalophilic and halotolerant bacteria belonging to aerobes were counted as $24{\times}10^6$ and $33{\times}10^5$ and the average number of those belonging to anaerobes $10{\times}10^7$ and $58{\times}10^5$ cells/g, respectively. The general bacteria isolated more in outer part than inner part and its average number was $62{\times}10^7$ cells/g. In the isolates, 2 aerobic acid producing strains were identified as Micrococcus spp., 3 anaerobic acid producing strains as Streptococcus sp., Pediococcus sp. and Lactobacillus sp., and 2 strains of aerobic general bacteria as Bacillus spp.

• Journal of the Korean Chemical Society
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• v.47 no.3
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• pp.273-282
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• 2003

A questionnaire on "atomic models and electron configuration" was performed on 34 of 11th grade and 38 of 12th grade students who took the Chemistry-II course in order to examine the degree of learning achievement. Also eight Chemistry-II textbooks published in the 6th curriculum were analyzed for the similarities and differences in dealing with this topic and possible improvements were discussed in conjunction with the questionnaire. The results of this questionnaire showed that the degree of learning achievement on the topics between two different classes were not much different in general, although a little difference was found. This indicates that the topics have been taught in early 11th grade but subsequent supplemental teaching has not been performed. To study on the topics of "atomic models and electron configuration" effectively and systematically, knowledge on the basic spectroscopy and quantum mechanics should be preceeded. However this could be practically difficult under the current high school curriculum. Therefore It would be necessary to describe the basic concepts for the quantum mechanics and spectroscopy schematically in the "Reference Materials" section of the textbook, even if it is not very long. On the other hand, the Chemistry-II textbooks analyzed in this work reveal, in general, to have the similar organization and explanation modes. However it has been analyzed that a connection between the Bohr and electron-cloud atomic models might be insufficient or position of electrons might be possible to be misunderstood by students in some textbooks.

• Journal of The Korean Association For Science Education
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• v.31 no.6
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• pp.931-941
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• 2011

This study aimed to examine the effects of argument-based chemistry laboratory investigations using the Science Writing Heuristic (SWH) approach on students' use and embedding of multimodal representations in summary writing. Participants of this study were thirty-nine freshman students majoring in science education at a National University in Korea. Argument-based chemistry laboratory investigations using the SWH approach were implemented for twenty-three students enrolled in one cohort, and the traditional chemistry laboratory teaching was implemented for 16 students enrolled in the other cohort. Summary writing samples were collected from students before and after the implementation. Summary writing samples produced by students were examined using an analysis framework for examining the use and embeddedness of multimodal representations. Summary writing was categorized into one of verbal mode, symbolic mode, and visual mode. With regard to the embedding of multi-modal representations, summary writing samples were analyzed in terms of 'constructing understanding,' 'integrating multiple modes,' 'providing valid claims and evidence,' and 'representing multiple modes.' Data analysis shows that the students of the SWH group were better at utilizing and embedding multimodal representations in summary writing as they provided evidence supporting their claims. This study provides important implications on pre-service science teacher education.

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.480-482
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• 2009

A 2-year-old, castrated male, Scottish fold cat was referred to Veterinary Medical Teaching Hospital of Seoul National University (VMTH-SNU) for evaluation of acute bilateral blindness after general anesthesia. For dental prophylaxis in local animal hospital, general anesthesia had been induced with intravenous acepromazine and ketamine, and maintained with isoflurane after intubation. At VMTH-SNU on next day, complete blood count, electrolytes and serum chemistry values were within normal ranges. On neurologic examination, visual placing and postural reactions like as hopping, hemiwalking and wheelborrowing were reduced on right hindlimb. On ophthalmic examination, menace responses were absent on both eyes and pupillary light reflex (PLR) reduced on right eye, but other reflex and fundus were normal. Prednisolone (2 mg/kg sid for 3 days) was administrated orally and tapered. Visual placing was possible on 2nd day, and postural reactions were recovered on 4th day after dental prophylaxis. Based on the process and recovery, this case was considered as postoperative visual loss (POVL) after general anesthesia.

• Resources Recycling
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• v.18 no.6
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• pp.3-9
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• 2009

The present review paper deals the liquid-liquid extraction (LLE) general principles and the basic fundamentals, general process of LLE followed by the importance of LLE reagents. LLE is a process of transferring a chemical compound from one liquid phase to a second liquid phase, immiscible with the first. In analytical chemistry, this method enjoys a favored position among separation techniques because of its simplicity, speed and wide scope. By utilizing apparatus no more complicated than a separatory funnel and requiring several minutes at most to perform, extraction procedures offer much to the analytical chemist.

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.85-93
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• 2004

The purpose of this research was to investigate the change of argumentation of middle school students when they participated in argument tasks with CASE(Cognitive acceleration through science education) programs. Students argumentations were divided into two categories; 'explanatory argumentation' and 'dialogic argumentation'. Several argumentation components were used in their argumentation. Among argumentation components, claim and ground took place more than half of argumentation components. The percentage of 'dialogic argumentation' was lower than the percentage of 'explanatory argumentation'. The percentage of 'dialogic argumentation' was getting higher during CASE intervention. CASE programs had more effect on symmetric group than asymmetric group, however it was unstable. In general, participation ratio in argumentation of the formal operational student was high and the ratio in argumentation of the transitional student was getting higher.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.244-244
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• 2017

Soil salinity due to accumulation of salts particularly sodium chloride affects agricultural lands and their vegetation. Generally, rice is a moderately sensitive plant with some cultivars with varying tolerance to salinity. Though there are physiological differences between salt-sensitive and salt-tolerant rice cultivars, both are still affected especially during high salinity and prolonged exposure. This also ultimately affects their indigenous bacterial endophytes particularly those that inhabit the rice seed endosphere. This study investigates the dynamic structure of seed bacterial endophytes of salt-sensitive and tolerant rice cultivars grown in different levels of soil salinity. Endophytic bacterial diversity was studied Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis. Results revealed a very interesting pattern of diversity and shifts in community structure of bacterial endophytes in the rice seeds. There is a general decrease in diversity for the salt-sensitive rice cultivar, IR29 as soil salinity increases. For the salt-tolerant cultivars, IC32 and IC37, diversity interestingly increased at moderate salinity then decreased at high soil salinity. The patterns of community structure is also strikingly different for the salt-sensitive and salt-tolerant rice cultivars. IR29 has a more even distribution of abundance, but under soil salinity, the community shifted where Curtobacterium, Pantoea, Flavobacterium and Microbacterium become the more dominant bacterial communities. For IC32 and IC37, the dominant bacterial groups under normal stress conditions were also the dominant bacterial groups during salt stress conditions. Their seed bacterial community is dominated by endophytes belonging to Microbacterium, Flavobacterium, Pantoea, Kosakonia and Enterobacter. Stenotrophomonas and Xanthomonas have not changed in terms of abundance under different salinity stress level in the salt-sensitive and salt-tolerant rice cultivars. This study showed that soil salinity greatly influenced the seed bacterial communities of rice seeds irrespective of their physiological tolerance to salinity.

• Applied Biological Chemistry
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• v.37 no.2
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• pp.124-129
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• 1994

The rate of hydrolysis of insecticidal $O,O-diethyl-{\alpha}-cyanobenzylideneamino-oxyphosphorothioate\;(Volaton^{\circledR})$ has been studied in 25% (v/v) aqueous dioxane. On the basis of solvent effect (pH 6.0; m=0.21, n=1.55, pH 12.0; m=0.42, n=3.14 & $|m|{\ll}|l|$), general base catalysis, hydrolysis product analysis, calculation of molecular orbital (MO) and rate equation, it may be concluded that the hydrolysis of Volaton proceeds through the $A_{AC}2$ mechanism via trigonal bipyramidal $(sp^3d^2)$ intermediate below pH 7.0, while above pH 9.0 the hydrolysis proceeds through the $B_{AC}2$ mechanism. Hydrolysis reactivity of Volaton depends on positive charge strength $(p{\gg}{\alpha}C_2)$ rather than steric hindrance. In the range between pH 7.0 and pH 9.0, these two reactions occur competitively.