• Title/Summary/Keyword: chemistry concept

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The Analysis of Analogies in Chemistry Content of Secondary School Science Textbooks Based on the 7th National Curriculum (제7차 중등 과학 교과서의 화학 영역에 사용된 비유 분석)

  • Cha, Jeong-Ho;Byun, Soon-Hwa;Noh, Tae-Hee
    • Journal of the Korean Chemical Society
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    • v.48 no.6
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    • pp.629-637
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    • 2004
  • 제7차 교육과정에 따른 중등 과학 교과서 중 화학 영역에 사용된 비유를 분석하였다. 전체 35권의 교과서에서 비유 사용 빈도는 325회로 13쪽마다 평균 1회 사용되었고, 단 한 번만 사용된 비유가 많았다. 유형별로는 기능적 비유, 언어와 그림을 모두 사용한 비유, 추상적 목표물을 구체적 비유물로 설명한 비유, 단순 비유와 부연 비유, 교사 중심 비유, 체계성이 낮은 비유가 많았고, 일상 비유와 작위적 비유가 비슷하게 사용되었다. 교과서 본문 중에 '비유‘라는 용어를 사용한 경우는 적었으며, 제한점에 대한 언급은 거의 없었다. 제6차 교육과정에 따른 과학 교과서에 비하여 쪽 당 비유의 수는 증가하였으나, 표현 방식, 작위성, 학습자 참여성을 제외한 모든 유형에서 비슷한 경향을 나타내었다. 이 결과들에 대한 교육적 시사점을 논의하였다.

Development of Modeling and control Methods for Multi-DOF dielectric polymer actuator

  • Jung, M.Y.;Jung, K.M.;Koo, J.C.;Choi, H.R.;Nam, J.D.;Lee, Y.K.
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.1225-1228
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    • 2004
  • Principles and mechanism of energy transduction of dielectric polymer materials are well known from the various smart material related publications. However their introduction to industrial actuator applications is limited mainly due to difficulties guarantee controllability and reliability. Most of the previous publications have elaborates energy transduction physics of chunk of polymer while development of construction methods for feasible actuators made of the material is rarely proposed. In the present article, a conceptual design of multi-DOF linear polymer actuator construction that is to be controllable with moderate level of control work os introduced. In addition, numerical models that are developed with a unified energy based approach are presented not only for basic working mechanism analysis of the polymetric soft actuator but for providing analytical foundation to expend the concept toward design of multi-DOF actuator controls.

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Ultra pH-Sensitive Polymeric Nanosystems for Tumor Targeting and chemotherapy

  • Lee, Eun-Seong;Na, Kun;Bae, You-Han
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.56-57
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    • 2006
  • The ultra pH-sensitive polymeric mixed micelles based on poly(L-histidine) chemistry and constructed from block copolymers containing polyHis, present four functionalities as decreasing pH: ligand exposure at pH 7.0, micelle destabilization below pH 6.8, enhanced DOX release and endosomal membrane disruption. The first functionality is expected to endow tumor pH specificity to nonspecific ligands and the rest ones may help to treat solid tumors that are hard-to-treat by conventional chemotherapy (resistant tumors). The concept was proven in vitro studies and in vivo model.

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A Liquid Theory. Nature of Liquid by Roulette Model (액체론. Roulette 모델로 설명되는 액체의 본질)

  • D. Chio;H. Park;M. Kim
    • Journal of the Korean Chemical Society
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    • v.22 no.1
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    • pp.1-6
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    • 1978
  • Feeling the potential field within a cell for various environments, every liquid molecule moves to minimize its potential energy. With this simple and fundamental concept, liquid molecules may be treated as a combination of three kinds of typical molecules characterized by Lennard-Jones and Devonshire's earlier work. We can get a partition function which has better functional from and less defects compared to the cell theory and the significant structure theory.

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Development of New Agrochemicals by Quantitative Structure-Activity Relationship (QSAR) Methodology -IV. A Tendency of Research and Prospect in Korea- (정량적인 구조-활성상관(QSAR) 기법에 의한 새로운 농약의 개발 -IV. 국내의 연구 동향과 전망-)

  • Sung, Nack-Do
    • Applied Biological Chemistry
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    • v.46 no.3
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    • pp.155-164
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    • 2003
  • It was reviewed for the status of domestic research before and after 1990's for search of a new pesticides using 2D QSAR of quantitative structure-activity relationship (QSAR) methodologies (Sung, Nack-Do (2002) Development of new agrochemicals by quantitative structure-activity relationship (QSAR) methodology. Kor J. Pestic. Sci. 6, 166-174, 231-243 & 7, 1-11) which was proposed according to Hansch-Fujita equation based on the concept of biological Hammett equation.

Optimum pH of Chicken peroxidase (닭의 과산화수소 분해효소의 최적pH)

  • Lee, Beom-Gyu;Kwon, Hyo-Shik;Kim, Kyoung-Eun;Yoon, Kil-Joong
    • Analytical Science and Technology
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    • v.14 no.3
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    • pp.286-289
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    • 2001
  • The effect of pH and the substrate concentration on the sensing ability of the chicken peroxidase enzyme electrode was examined quanititatively. Using the new Michaelis-Menten equation, to which pH concept was introduced, enabled to calculate all kinds of dissociation constant related to chicken peroxidase and subsequently to determine the optimum pH of the sensor.

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Binding Set Analysis for Interaction of Human Serum Albumin with Cethyl Trimethylammonium Bromide

  • Bordbar, Abdol-Khalegh;Sohrabi, Nasrin;Gharibi, Hossain
    • Bulletin of the Korean Chemical Society
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    • v.25 no.6
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    • pp.791-795
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    • 2004
  • The binding of cethyl trimethylammonium bromide, (CTAB) with human serum albumin (HSA) has been investigated at 5 mM phosphate buffer pH 7.0, 27 $^{\circ}C$ and various ionic strength using ion selective membrane electrodes. This method is faster and much more accurate than equilibrium dialysis technique, so provides sufficient and accurate data for binding data analysis. A novel and simple method was introduced for resolution and characterization of binding sets on basis of binding capacity concept. The values of Hill binding parameters were estimated for each set and used for calculation of intrinsic binding affinity. The results interpreted on basis of nature of forces which interfered in the interaction and represent the existence of three and two binding sets for binding of CTAB at $10^{-4}$ and $10^{-3}$ M of NaBr, respectively.

Preferential Solvation and Statistical Analysis for Solvent Polarity Parameters in MeOH Binary Mixtures

  • Sakong Yeol;Yoo Seoung-Kyo;Lee Ikchoon
    • Bulletin of the Korean Chemical Society
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    • v.13 no.6
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    • pp.636-642
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    • 1992
  • Preferential solvation (PS) phenomena of solutes based on solvent polarity, $E_T$ and AN, were studied by UV/vis. and NMR spectra in MeOH binary mixtures. According to the extent of solvent-solvent interaction, different solvation phenomena were found. PS concept was applied to explain the reactivity of tert-butyl halides solvolysis. The findings of solvation phenomena have been related to the rate of solvolysis and PS suggested as a reason for the solvent dependence of the rates of reaction. Moreover, we found that the results of principal components analysis using six parameters are in good accordance with the results of PS phenomena in mixed methanol systems.

Standardizing GC-FID Measurement of Nonmethane Hydrocarbons in Air for International Intercomparison Using Retention Index and Effective Carbon Number Concept

  • Liaw, Sheng-Ju;Tso, Tai-Ly
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.807-814
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    • 1995
  • Accurate measurements of ozone precursors are required to understand the process and extent of ozone formation in rural and urban areas. Nonmethane hydrocarbons (NMHCs) have been identified as important ozone precursors. Identification and quantification of NMHCs are difficult because of the large number present and the wide molecular weight range encountered in typical air samples. A major plan of the research team of the Climate and Air Quality Taiwan Station (CATs) was the measurement of atmospheric nonmethane hydrocarbons. An analytical method has been development for the analysis of the individual nonmethane hydrocarbons in ambient air at ppb (v) and subppb(v) levels. The whole ambient air samples were collected in canisters and analyzed by GC-FID with $Al_2O_3$/KCl PLOT column. Our targeted for quantitative analysis 43 compounds that may be substantial contributors to ozone formation. The retention indices and molar response factors of some commercially available $C_2{\sim}C_{10}$ hydrocarbons were determined and used to identify and quantify air samples. A quality assurance program was instituted to ensure that good measurements were made by participating in the International Nonmethane Hydrocarbon Intercomparison Experiments (NOMHICE).

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The Acid-Base-Concepts of Korean Secondary Students (우리나라 중.고등학교 학생이 갖고 있는 '산과 염기'의 개념에 관한 연구 -서울 일부지역의 여학생을 중심으로-)

  • Kim, Hwa-Sook
    • Journal of The Korean Association For Science Education
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    • v.12 no.2
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    • pp.55-65
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    • 1992
  • The purpose of the study is to compare the learning contents of theme acids and bases that are commonly dealed with in elementary, middle and high schools m Korea and to investigate the acid-base-concepts of secondary students. The results of the study were as follows: 1) Many students did not have an interest in the chemistry and they pointed out the necessity of many experiments and practices and its application to the practical life. 2) It is found that most of textbooks used in the elementary school are written to make the students have an interest in the science through the experiments and pratices. However the textbooks used in the secondary school are too theoretically written so that many students are likely to lose the interests in the chemistry. 3) Although students had already learned Arrhenius's acid-base-concept, many students tried to solve the question with Liebig's theory as a acid-base-concept. This misconception might be caused by learning by cramming and teaching too theoretically. Accordingly, it is necessary that the education of science is carried out to make the students have an interest in the science by providing the students with the much more experiments and practices and also applying it to the practical life.

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