• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.23-23
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• 2009

Recently, the nanowire configuration of GST showed nanosecond-level phase switch at very low power dissipation, suggesting that the nanowires could be ideal for data storage devices. In spite of many advantages of IST materials, their feasibility in both thin films and nanowires for electronic memories has not been extensively investigated. The synthesis of the chalcogenide nanowires was mainly preformed via a vapor transport process such as vapor-liquid-solid (VLS) growth at a high temperature. However, in this study, IST nanowires as well as thin films were prepared at a low temperature (${\sim}250^{\circ}C$) by metal organic chemical vapor deposition(MOCVD) method, which is possible for large area deposition. The IST films and/or nanowires were selectively grown by a control of working pressure at a constant growth temperature by MOCVD. In-Sb-Te NWs will be good candidate materials for high density PRAM applications. And MOCVD system is powerful for applying ultra scale integration cell.

• 공학교육연구
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• 제13권5호
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• pp.55-60
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• 2010

Chemistry laboratory class was produced for senior high school freshmen with the cooperation of university staffs, high school teachers and the university students. Although the students who will take the lab class are senior high school freshmen, we decided to prepare four experiments that are simple and have highly visible reactions or transformation. That is, 1) Water purification, 2) Surface modification, 3) Briggs-Rauscher reaction, and 4) Polymer synthesis and characterization. After the safety guideline and experiment instructions by the faculty staffs, two teaching assistants (TAs) supervised each experiment. Since taking a direct part in it will provide stronger impact than only being one who is just watching the experiment, all experiments contained some process that the high school students must handle the reagents, tools or the equipment, by themselves. Although, the operation performed by the students was limited to a series of simple actions, the various unique phenomena presented by the experiments impressed the students. The lab class was fruitful not only for high school students, but also good for university students. The lab class provided good opportunity for them to improve the abilities to teach and guide someone.

• Reproductive and Developmental Biology
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• 제35권1호
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• pp.1-8
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• 2011

Techniques to evaluate gene expression profiling, such as sufficiently sensitive cDNA microarrays or real-time quantitative PCR, are efficient methods for monitoring human pluripotent stem cell (hESC/iPSC) cultures. However, most of these high-throughput tests have a limited use due to high cost, extended turn-around time, and the involvement of highly specialized technical expertise. Hence, there is an urgency of rapid, cost-effective, robust, yet sensitive method development for routine screening of hESCs/hiPSCs. A critical requirement in hESC/hiPSC cultures is to maintain a uniform undifferentiated state and to determine their differentiation capacity by showing the expression of gene markers representing all three germ layers, including ectoderm, mesoderm, and endoderm. To quantify the modulation of gene expression in hESCs/hiPSC during their propagation, expansion, and differentiation via embryoid body (EB) formation, we developed a simple, rapid, inexpensive, and definitive multimarker, semiquantitative multiplex RT-PCR platform technology. Among the 9 gene primers tested, 5 were pluripotent markers comprising set 1, and 3 lineage-specific markers were combined as set 2, respectively. We found that these 2 sets were not only effective in determining the relative differentiation in hESCs/hiPSCs, but were easily reproducible. In this study, we used the hES/hiPS cell lines to standardize the technique. This multiplex RT-PCR assay is flexible and, by selecting appropriate reporter genes, can be designed for characterization of different hESC/hiPSC lines during routine maintenance and directed differentiation.

• Journal of Periodontal and Implant Science
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• 제47권6호
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• pp.388-401
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• 2017

Purpose: The physicochemical properties of a xenograft are very important because they strongly influence the bone regeneration capabilities of the graft material. Even though porcine xenografts have many advantages, only a few porcine xenografts are commercially available, and most of their physicochemical characteristics have yet to be reported. Thus, in this work we aimed to investigate the physicochemical characteristics of a porcine bone grafting material and compare them with those of 2 commercially available bovine xenografts to assess the potential of xenogenic porcine bone graft materials for dental applications. Methods: We used various characterization techniques, such as scanning electron microscopy, the Brunauer-Emmett-Teller adsorption method, atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and others, to compare the physicochemical properties of xenografts of different origins. Results: The porcine bone grafting material had relatively high porosity (78.4%) and a large average specific surface area (SSA; $69.9m^2/g$), with high surface roughness (10-point average roughness, $4.47{\mu}m$) and sub-100-nm hydroxyapatite crystals on the surface. Moreover, this material presented a significant fraction of sub-100-nm pores, with negligible amounts of residual organic substances. Apart from some minor differences, the overall characteristics of the porcine bone grafting material were very similar to those of one of the bovine bone grafting material. However, many of these morphostructural properties were significantly different from the other bovine bone grafting material, which exhibited relatively smooth surface morphology with a porosity of 62.0% and an average SSA of $0.5m^2/g$. Conclusions: Considering that both bovine bone grafting materials have been successfully used in oral surgery applications in the last few decades, this work shows that the porcinederived grafting material possesses most of the key physiochemical characteristics required for its application as a highly efficient xenograft material for bone replacement.

• Parasites, Hosts and Diseases
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• 제47권4호
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• pp.337-344
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• 2009

In a previous study, we reported our discovery of Acanthamoeba contamination in domestic tap water; in that study, we determined that some Acanthamoeba strains harbor endosymbiotic bacteria, via our molecular characterization by mitochondrial DNA restriction fragment length polymorphism (Mt DNA RFLP). Five (29.4%) among 17 Acanthamoeba isolates contained endosymbionts in their cytoplasm, as demonstrated via orcein staining. In order to estimate their pathogenicity, we conducted a genetic characterization of the endosymbionts in Acanthamoeba isolated from domestic tap water via 16S rDNA sequencing. The endosymbionts of Acanthamoeba sp. KA/WP3 and KA/WP4 evidenced the highest level of similarity, at 97% of the recently published 16S rDNA sequence of the bacterium, Candidatus Amoebophilus asiaticus. The endosymbionts of Acanthamoeba sp. KA/WP8 and KA/WP12 shared a 97% sequence similarity with each other, and were also highly similar to Candidatus Odyssella thessalonicensis, a member of the $\alpha$-proteobacteria. The endosymbiont of Acanthamoeba sp. KA/WP9 exhibits a high degree of similarity (85-95%) with genus Methylophilus, which is not yet known to harbor any endosymbionts. This is the first report, to the best of our knowledge, to show that Methylophilus spp. can live in the cytoplasm of Acanthamoeba.

• 열처리공학회지
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• 제24권1호
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• pp.37-44
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• 2011

High temperature wear of AlCrN coated tool steels sliding against the ultra-high strength boron steels used for hot press forming has been studied. The sliding wear tests have been carried out using a pin-on-disc of configuration under applied normal load of 50 N for 20 min with heating the ultra-high strength boron steels up to $800^{\circ}C$. Characterizations of tribolayers formed on the contacting surfaces between the tribopairs of the AlCrN coated tool steels and the ultra-high strength boron steels have been studied. It was found on the tribolayers of the AlCrN coated tool steels that microcracking and oxides containing Fe and Cr to increase friction coefficient were formed at the early stage of sliding wear, followed by the generation of the smeared oxide layers containing Fe transferred from the tribopair to decrease friction coefficient. This may mainly contribute to very low specific wear rate of the AlCrN coated tool steels sliding against the ultra-high strength boron steels, resulting from oxideoxide contact between the tribopair.

• International Journal of Advanced Culture Technology
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• 제9권3호
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• pp.174-180
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• 2021

The necessity of this study is as follows. A decrease in the number of newborns, an increase in the youth unemployment rate, and a decrease in the employment rate are having a fatal impact on universities. To help increase the employment rate of universities, we intend to utilize Big Data of university public information. Big data refers to the process of collecting and analyzing data, and includes all business processes of finding data, reprocessing information in an easy-to-understand manner, and selling information to people and institutions. Big data technology can be divided into technologies for storing, refining, analyzing, and predicting big data. The purpose of this study is to find the vision and special department of a university with a high employment rate by using big data technology. As a result of the study, big data was collected from 227 universities on www.academyinfo.go.kr site, We selected 130 meaningful universities and selected 25 universities with high employment rates and 25 universities with low employment rates. In conclusion, the university with a high employment rate can first be said to have a student-centered vision and university specialization. The reason is that, for universities with a high employment rate, the vision was to foster talents and specialize, whereas for universities with a low employment rate, regional bases took precedence. Second, universities with a high employment rate have a high interest in specialized departments. This is because, as a result of checking the presence or absence of a characterization plan, universities with a high employment rate were twice as high (21/7). Third, universities with high employment rates promote social needs and characterization. This is because the characteristic departments of universities with high employment rates are in the order of future technology and nursing and health, while universities with low employment rates promoted school-centered specialization in future technology and culture, tourism and art. In summary, universities with high employment rates showed high interest in student-centered vision and development of special departments for social needs.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.615-621
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• 2013

본 연구에서는 수계 레독스 흐름전지에서 사용하는 멤브레인 특성분석방법을 개선하여 비수계 레독스 흐름 전지를 위한 멤브레인 특성분석방법을 확립하였다. 비수계 레독스 흐름 전지에 적합한 멤브레인 특성을 확인하기 위해 상용 멤브레인의 이온교환능력, 이동수, 이온 전도도, 활물질 투과도, 전지효율 실험 등 특성분석들을 수행하였다. 상용 음이온 교환 멤브레인의 특성분석 실험을 통해 충 방전 효율 및 에너지효율과 이온 선택성의 상관관계를 조사하였다. Neosepta AHA 음이온 교환 멤브레인은 이동수 측정에서 0.81의 값으로 비수계 전해질에서 비교적 낮은 이온 선택성을 보였지만, 충방전 전지효율 평가에서는 92%의 충 방전효율과 86%의 에너지효율을 각각 나타내었다. 또한 이온의 선택성이 없는 다공성 멤브레인은 높은 전류밀도의 비수계 레독스 흐름 전지에 적절함을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2013

The electrical characterization of Au islands on TiO2 at nanometer scale (as a Schottky nanodiode) has been studied with conductive atomic force microscopy in ultra-high vacuum. The diverse sizes of the Au islands were formed by using self-assembled patterns on n-type TiO2 semiconductor film using the Langmuir-Blodgett process. Local conductance images showing the current flowing through the TiN coated AFM probe to the surface of the Au islands on TiO2 was simultaneously obtained with topography, while a positive sample bias is applied. The boundary of the Au islands revealed a higher current flow than that of the inner Au islands in current AFM images, with the forward bias presumably due to the surface plasmon resonance. The nanoscale Schottky barrier height of the Au/TiO2 Schottky nanodiode was obtained by fitting the I-V curve to the thermionic emission equation. The local resistance of the Au/TiO2 nanodiode appeared to be higher at the larger Au islands than at the smaller islands. The results suggest that conductive atomic force microscopy can be used to reveal the I-V characterization of metal size dependence and the electrical effects of surface plasmon on a metal-semiconductor Schottky diode at nanometer scale.

• 한국표면공학회지
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• 제57권2호
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• pp.71-85
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• 2024

This article provides an overview of Raman spectroscopy and its practical applications for surface analysis of semiconductor processes including real-time monitoring. Raman spectroscopy is a technique that uses the inelastic scattering of light to provide information on molecular structure and vibrations. Since its inception in 1928, Raman spectroscopy has undergone continuous development, and with the advent of SERS(Surface Enhanced Raman Spectroscopy), TERS(Tip Enhanced Raman Spectroscopy), and confocal Raman spectroscopy, it has proven to be highly advantageous in nano-scale analysis due to its high resolution, high sensitivity, and non-destructive nature. In the field of semiconductor processing, Raman spectroscopy is particularly useful for substrate stress and interface characterization, quality analysis of thin films, elucidation of etching process mechanisms, and detection of residues.