• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.953-958
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• 2007

Anchoring quantum dots (QDs) onto thermodynamically stable, large band gap oxide semiconductors is a very important strategy to enhance their quantum yields for solar energy conversion in both visible and near-IR regions. We describe a general procedure for anchoring a few chalcogenide QDs onto the titanium oxide layer. To anchor the colloidal QDs onto a mesoporous TiO2 layer, linker molecules containing both carboxylate and thiol functional groups were initially attached to TiO2 layers and subsequently used to capture dispersed QDs with the thiol group. Employing the procedure, we exploited cadmium selenide (CdSe) and cadmium telluride (CdTe) quantum dots (QDs) as inorganic sensitizers for a large band gap TiO2 layer of dye-sensitized solar cells (DSSCs). Their attachment was confirmed by naked eyes, absorption spectra, and photovoltaic effects. A few QD-TiO2 systems thus obtained have been characterized for photoelectrochemical solar energy conversion.

• Journal of Magnetics
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• 제22권1호
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• pp.49-54
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• 2017

The significant reduction of the image quality caused by the magnetic field of samples is a major problem affecting the application of SEM (scanning electron microscopy) in the analysis of electronic devices. The main reason for this is that the electron trajectory is deflected by the Lorentz force. The usual solution to this problem is degaussing the sample at high temperatures. However, due to the poor heat resistance of some electronic components, it is imperative to find a method that can reduce the impact of magnetic field on the image quality and is straightforward and easy to operate without destroying the sample. In this paper, the influence of different magnetic field directions on the imaging quality was discussed by combining the experiment and software simulation. The principle of the method was studied, and the best observation direction was obtained.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2355-2364
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• 2018

We evaluated the effect of particle size and associated dynamics on a hydrocyclone separation process in order to understand the movement of the particle trajectories inside the hydrocyclone via numerical analysis, with particles of acid hydrolysis residues discharged in $TiO_2$ production via the sulfate method as a case study. The values obtained from the numerical simulation were successfully compared with those from experimental tests in the literature, allowing a description of the dynamics of the particles, their acting forces, and their relevant properties together with separation efficiency. The results showed that particle motion is jointly controlled by the drag force, the pressure gradient force and the centrifugal force. With increasing particle size, the influence of the drag force is weakened, whereas that of the centrifugal force and pressure gradient is strengthened. Factors including particle density, slurry viscosity, and inlet slurry flow rate also contribute to a clear and useful understanding of particle motion behavior in the hydrocyclone as a method for improving the separation efficiency.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1773-1776
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• 2012

• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.577-580
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• 2004

• 대한지구과학교육학회지
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• 제13권1호
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• pp.121-133
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• 2020

본 연구는 융합(STEM)교육의 핵심인 공학 설계를 기반으로 과학 수업에서 공학을 의미있고 쉽게 융함하여 수업을 설계할 수 있도록 수업 준거틀을 제안 한 것이다. 본 연구에서 개발된 과학·공학 융합 수업 준거틀은 과학과 공학 융합 교육에 대한 국내외 이론적, 실제적 선행 연구 분석과 전문가 토의, 그리고 현장교사들의 피드백에 근거하여 개발되었다. 과학·공학 융합 수업 준거틀은 과학 수업에서 공학 설계를 주요 교수법 및 문제해결 방법으로 사용하며, 선행 연구에서 제시된 공학 융합 수업의 핵심요소와 학년군별 성취수준을 고려하여 공학 설계에 대한 이해가 부족한 현장 교사들이 쉽게 공학 설계를 과학 수업에 도입할 수 있는 방법을 제공한다. 또한 본 연구에서 개발된 과학·공학 융합 수업 준거틀은 복잡하게 제시된 한국 STEAM 교육 준거틀의 단점을 보완하여 현장교사뿐 아니라 예비교사들이 쉽게 공학적 설계와 문제해결과정에 대해 이해하고 이를 적용하여 과학 융합 수업을 설계하는데 구체적인 지침을 제공할 수 있다.

• Molecules and Cells
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• 제27권1호
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• pp.21-37
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• 2009

Map-based cloning to find genes of interest, marker-assisted selection (MAS), and marker-assisted breeding (MAB) all require good genetic maps with high reproducible markers. For map construction as well as chromosome assignment, development of single copy PCR-based markers and map integration process are necessary. In this study, the 132 markers (57 STS from BAC-end sequences, 13 STS from RFLP, and 62 SSR) were newly developed as single copy type PCR-based markers. They were used together with 1830 markers previously developed in our lab to construct an integrated map with the Joinmap 3.0 program. This integrated map contained 169 SSR, 354 RFLP, 23 STS from BAC-end sequences, 6 STS from RFLP, 152 AFLP, 51 WRKY, and 99 rRAMP markers on 12 chromosomes. The integrated map contained four genetic maps of two interspecific (Capsicum annuum 'TF68' and C. chinense 'Habanero') and two intraspecific (C. annuum 'CM334' and C. annuum 'Chilsungcho') populations of peppers. This constructed integrated map consisted of 805 markers (map distance of 1858 cM) in interspecific populations and 745 markers (map distance of 1892 cM) in intraspecific populations. The used pepper STS were first developed from end sequences of BAC clones from Capsicum annuum 'CM334'. This integrated map will provide useful information for construction of future pepper genetic maps and for assignment of linkage groups to pepper chromosomes.

• 한국과학교육학회지
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• 제28권5호
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• pp.409-423
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• 2008

최근 과학교육 분야의 연구들에 의하면 학생들은 과학수업 시 다양한 어려움을 지각하며 수업 후에도 이러한 어려움이 잘 해소되지 않는다는 연구 결과가 보고되고 있다. 그러나 학생들이 느끼는 과학학습의 어려움과 그 원인을 조사하여 이를 해소시키기 위한 연구는 아직 부족한 실정이다. 따라서 학생들의 과학학습 어려움에 대한 체계적인 분석과 더불어 어려움을 해소하고 학습효과를 향상시킬 수 있는 새로운 수업모형 개발이 필요하다. 본 연구에서는 최근의 과학학습 과정에서 학생의 겪는 어려움과 기존 과학수업 모형에 관한 선행연구들을 조사하여, 이 결과를 통합적 정신모형이론 관점에서 분석하였다. 이러한 과정을 거쳐 과학학습 어려움 해소를 도울 수 있는 통합적 정신모형 이론에 기반한 4M 순환학습 수업모형을 개발하였다.

• 대한화학회지
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• 제57권4호
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• pp.489-492
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• 2013

N-doped $TiO_2$ microcuboids were successfully prepared by a simple one-pot hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. It was found that the N-doped $TiO_2$ microcuboids enhanced absorption in the visible light region, and exhibited higher activity for photocatalytic degradation of model dyes. Based on the experimental results, a visible light induced photocatalytic mechanism was proposed for N-doped anatase $TiO_2$ microcuboids.

• The Plant Pathology Journal
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• 제38권2호
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• pp.167-174
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• 2022

Pseudomonas amygdali is a hemibiotrophic phytopathogen that causes disease in woody and herbaceous plants. Complete genomes of four P. amygdali pathovars were comparatively analyzed to decipher the impact of genomic diversity on host colonization. The pan-genome indicated that 3,928 core genes are conserved among pathovars, while 504-1,009 are unique to specific pathovars. The unique genome contained many mobile elements and exhibited a functional distribution different from the core genome. Genes involved in O-antigen biosynthesis and antimicrobial peptide resistance were significantly enriched for adaptation to hostile environments. While the type III secretion system was distributed in the core genome, unique genomes revealed a different organization of secretion systems as follows: type I in pv. tabaci, type II in pv. japonicus, type IV in pv. morsprunorum, and type VI in pv. lachrymans. These findings provide genetic insight into the dynamic interactions of the bacteria with plant hosts.