• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.301-301
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• 2011

최근 고밀도 메모리 반도체의 재료와 빠른 응답을 요구하는 나노입자를 이용한 비휘발성 메모리 소자의 제작에 대한 연구가 활발히 진행되고 있다. 그에 따른 기존의 플래쉬 메모리가 가지는 문제점을 개선하기 위해서 균일하고 규칙적으로 분포하는 새로운 나노소재의 개발과 비휘발성, 고속 동작, 고집적도, 저전력 소자의 공정기술이 요구되고 있다. 또한 부유게이트에 축적되는 저장되는 전하량을 증가시키기 위한 새로운 소자구조 개발이 필요하다. 한편, 실리 사이드 계열의 나노입자는 금속 나노입자와 달리 현 실리콘 기반의 반도체 공정에서 장점을 가지고 있다. 따라서 본 연구에서는 화합물 중에서 비휘발성 메모리 장치의 전기적 특성을 향상 시킬 수 있는 실리사이드 계열의 바나듐 실리사이드(V3Si) 박막을 열처리 과정을 통하여 수 nm 크기의 나노입자로 제작하였다. 소자의 제작은 p-Si기판에 실리콘산화막 터널층(5 nm 두께)을 건식 산화법으로 성장 후, 바나듐 실리사이드 금속박막을 RF 마그네트론 스퍼터 시스템을 이용하여 4~6 nm 두께로 터널 베리어 위에 증착하고, 그 위에 초고진공 마그네트론 스퍼터링을 이용하여 SiO2 컨트롤 산화막층 (20 nm)을 형성시켰다. 여기서 V3Si 나노입자 형성을 위해 급속 열처리법으로 질소 분위기에서 800$^{\circ}C$로 5초 동안 열처리하여 하였으며, 마지막으로 열 기화 시스템을 통하여 알루미늄 전극(직경 200 ${\mu}m$, 두께 200 nm)을 증착하여 소자를 제작하였다. 제작된 구조는 금속 산화막 반도체구조를 가지는 나노 부유게이트 커패시터이며, 제작된 시편은 투사전자현미경을 이용하여 나노입자의 크기와 균일성을 확인했다. 소자의 전기적인 측정을 E4980A capacitor parameter analyzer와 Agilent 81104A pulse pattern generator system을 이용한 전기용량-전압 측정을 통해 전하저장 효과 및 메모리 동작 특성들을 분석하고, 열처리 조건에 따라 형성되는 V3Si 의 조성을 엑스선 광전자 분광법을 이용하여 확인하였다.

• International Journal of Railway
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• 제2권3호
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• pp.118-123
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• 2009

Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.

• 센서학회지
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• 제17권5호
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• pp.369-374
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• 2008

A novel fiber optic surface plasmon resonance (SPR) sensor using cyclic olefin copolymer (COC) prism with the spectral modulation is presented. The SPR sensor chip is fabricated using the SU-8 photolithography, Ni-electroplating and COC injection molding process. The sidewall of the COC prism is partially deposited with Au/Cr (45/2.nm thickness) by e-beam evaporator, and the thermal bonding process is conducted for micro fluidic channels and optical fibers alignment. The SPR spectrum for a phosphate buffered saline (0.1.M PBS, pH.7.2) solution shows a distinctive dip at 1300.nm wavelength, which shifts toward longer wavelength with respect to the bovine serum albumin (BSA)concentrations. The sensitivity of the wavelength shift is $1.16\;nm{\cdot}{\mu}g^{-1}{\cdot}{\mu}l^{-1}$. From the wavelength of SPR dips, the refractive indices (RI) of the BSA solutions can be theoretically calculated using Kretchmann configuration, and the change rate of the RI was found to be $2.3{\times}10^{-5}RI{\cdot}{\mu}g^{-1}{\cdot}l^{-1}$. The realized fiber optic SPR sensor with a COC prism has clearly shown the feasibility of a new disposable, low cost and miniaturized SPR biosensor for biochemical molecular analyses.

• Journal of Veterinary Science
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• 제22권3호
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• pp.25.1-25.16
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• 2021

Background: Malignant lymphoma is the most common hematopoietic malignancy in dogs, and relapse is frequently seen despite aggressive initial treatment. In order for the treatment of these recurrent lymphomas in dogs to be effective, it is important to choose a personalized and sensitive anticancer agent. To provide a reliable tool for drug development and for personalized cancer therapy, it is critical to maintain key characteristics of the original tumor. Objectives: In this study, we established a model of hybrid tumor/stromal spheroids and investigated the association between canine lymphoma cell line (GL-1) and canine lymph node (LN)-derived stromal cells (SCs). Methods: A hybrid spheroid model consisting of GL-1 cells and LN-derived SC was created using ultra low attachment plate. The relationship between SCs and tumor cells (TCs) was investigated using a coculture system. Results: TCs cocultured with SCs were found to have significantly upregulated multidrug resistance genes, such as P-qp, MRP1, and BCRP, compared with TC monocultures. Additionally, it was revealed that coculture with SCs reduced doxorubicin-induced apoptosis and G2/M cell cycle arrest of GL-1 cells. Conclusions: SCs upregulated multidrug resistance genes in TCs and influenced apoptosis and the cell cycle of TCs in the presence of anticancer drugs. This study revealed that understanding the interaction between the tumor microenvironment and TCs is essential in designing experimental approaches to personalized medicine and to predict the effect of drugs.

• 한국동물생명공학회지
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• 제36권2호
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• pp.69-75
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• 2021

Cryopreservation is a widely-used efficient means of long-term sperm preservation. However, unlike other types of semen, cryopreserved boar semen has reduced fertility and the efforts continue to optimize post-thawing sperm recovery. In this study, we evaluated the effects of various washing solutions (Hulsen solution, lab-made DPBS and commercial DPBS) on post-thawing porcine sperm kinematics (CASA system), viability (SYBR-14/PI) and acrosome integrity (PSA/FITC). We also examined the effect of washing-centrifugation on frozen-thawed semen kinematics. The results indicate that type of washing solution and post-thawing centrifugation alters parameters linked to sperm quality (total motility, progressive motility, viability and acrosome integrity). Significantly higher (p < 0.05) motility and progressive motility were obtained when cryopreserved semen was processed with Hulsen solution. The post-thaw percentage of live and intact acrosomal sperm was significantly higher in group 1 (Hulsen solution) as compared to other groups. Following thawing-centrifugation, the results showed significantly higher motility and progressive motility in group 1 than other groups. However, the latter two DPBS groups did not differ statistically. Taken together, Frozen-thawed spermatozoa motility, acrosome integrity and viability can be affected by the type of washing solution used. Moreover, centrifugation of frozen-thawed semen has an unfavorable effect on total motility and progressive motility.

• Journal of Microbiology and Biotechnology
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• 제32권11호
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• pp.1471-1478
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• 2022

2'-Fucosyllactose (2'-FL), the most abundant fucosylated oligosaccharide in human milk, has multiple beneficial effects on human health. However, its biosynthesis by metabolically engineered Escherichia coli is often hampered owing to the insolubility and instability of α-1,2-fucosyltransferase (the rate-limiting enzyme). In this study, we aimed to enhance 2'-FL production by increasing the expression of soluble α-1,2-fucosyltransferase from Helicobacter pylori (FucT2). Because structural information regarding FucT2 has not been unveiled, we decided to improve the expression of soluble FucT2 in E. coli via directed evolution using a protein solubility biosensor that links protein solubility to antimicrobial resistance. For such a system to be viable, the activity of kanamycin resistance protein (Kan^R) should be dependent on FucT2 solubility. Kan^R was fused to the C-terminus of mutant libraries of FucT2, which were generated using a combination of error-prone PCR and DNA shuffling. Notably, one round of the directed evolution process, which consisted of mutant library generation and selection based on kanamycin resistance, resulted in a significant increase in the expression level of soluble FucT2. As a result, a batch fermentation with the ΔL M15 pBCGW strain, expressing the FucT2 mutant (F#1-5) isolated from the first round of the directed evolution process, resulted in the production of 0.31 g/l 2'-FL with a yield of 0.22 g 2'-FL/g lactose, showing 1.72- and 1.51-fold increase in the titer and yield, respectively, compared to those of the control strain. The simple and powerful method developed in this study could be applied to enhance the solubility of other unstable enzymes.

• Journal of Periodontal and Implant Science
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• 제53권1호
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• pp.20-37
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• 2023

Purpose: Our pilot study showed that a 3-dimensional dual drug delivery scaffold (DDDS) loaded with Chinese herbs significantly increased the regenerated bone volume fraction. This study aimed to confirm the synergistic anti-inflammatory and osteogenic preclinical effects of this system. Methods: The targets and pathways of parthenolide and naringin were predicted. Three cell models were used to assess the anti-inflammatory effects of parthenolide and the osteogenic effects of naringin. First, the distance between the cementoenamel junction and alveolar bone crest (CEJ-ABC) and the bone mineral density (BMD) of surgical defects were measured in a rat model of periodontitis with periodontal fenestration defects. Additionally, the mRNA expression levels of matrix metallopeptidase 9 (MMP9) and alkaline phosphatase (ALP) were measured. Furthermore, the number of inflammatory cells and osteoclasts, as well as the protein expression levels of tumor necrosis factor-alpha (TNF-α) and levels of ALP were determined. Results: Target prediction suggested prostaglandin peroxidase synthase (PTGS2) as a potential target of parthenolide, while cytochrome P450 family 19 subfamily A1 (CYP19A1) and taste 2 receptor member 31 (TAS2R31) were potential targets of naringin. Parthenolide mainly targeted inflammation-related pathways, while naringin participated in steroid hormone synthesis and taste transduction. In vitro experiments revealed significant antiinflammatory effects of parthenolide on RAW264.7 cells, and significant osteogenic effects of naringin on bone marrow mesenchymal stem cells and MC3T3-E1 cells. DDDS loaded with parthenolide and naringin decreased the CEJ-ABC distance and increased BMD and ALP levels in a time-dependent manner. Inflammation was significantly alleviated after 14 days of DDDS treatment. Additionally, after 56 days, the DDDS group exhibited the highest BMD and ALP levels. Conclusions: DDDS loaded with parthenolide and naringin in a rat model achieved significant synergistic anti-inflammatory and osteogenic effects, providing powerful preclinical evidence.

• Asian-Australasian Journal of Animal Sciences
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• 제18권12호
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• pp.1701-1707
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• 2005

This study deals with the characterization of porcine PIK3C3 and association tests with quantitative traits. PIK3C3 belongs to the class 3 PI3Ks that participate in the regulation of hepatic glucose output, glycogen synthase, and antilipolysis in typical insulin target cells such as those in the such as liver, muscle system, and fat. On the analysis of full-length mRNA sequence, the length of the PIK3C3 CDS was recorded as 2,664 bps. As well, nucleotide and amino acid identities between human and pig subjects were 92% and 99%, respectively. Five SNPs were detected over 5 exons. We performed genotyping by using a SNP C2604T on exon24 for 145 F$_2$ animals (from a cross between Korean native boars and Landrace sows) by PCR-RFLP analysis with Hpy8I used to investigate the relationship between growth and fat depot traits. In the total association analysis, which doesn' consider transmission disequilibrium, the SNP showed a significant effect (p<0.05) on body weight and carcass fat at 30 weeks of age as well as a highly significant effect (p<0.01) on back fat. In an additional sib-pair analysis, C allele still showed positive and significant effects (p<0.05) on back fat thickness and carcass fat. Moreover, the effects of C allele on the means of within-family components for carcass fat and back fat were estimated as 2.76 kg and 5.07 mm, respectively. As a result, the SNP of porcine PIK3C3 discovered in this study could be utilized as a possible genetic marker for the selection of pigs that possess low levels of back fat and carcass fat at the slaughter weight.

• 한국축산시설환경학회지
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• 제16권3호
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• pp.167-174
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• 2010

본 시험은 돈분뇨 슬러리�l 액상처리효과를 증시키기 위하여 담체를 활용한 폭기조 운영조건 변화에 따른 처리효과를 측정하기 위한 목적으로 수행하였으며, 시험 결과는 다음과 같다. 1. BOD와 COD의 제거효율은 일반 관행폭기에 비해 담체 처리구에서 더 좋은 결과를 보였다. 담체 중에서도 섬유상 담체에서 그 제거율이 높았다. SS의 경우는 관행 폭기처리구보다 담체 적용구에서 그 변화정도가 적었다. 반면에 질소의 제거율은 담체 적용에 의해 뚜렷하게 개선되었다. 2. 슬러지 침강성과 농축성을 나타내는 SVI 값은 대조구에서 나타난 25%에 비해 담체 적용구가 높았으며 섬유상 담체적용구에서 45%의 가장 높은 감소정도를 보였다. 3. 관행 폭기구에서의 슬러지 발생량을 100으로 기준하여 볼 때 섬유담체에서 약 85% 정도의 슬러지 발생량을 보임으로써 각 처리구중에서 슬러지 발생량이 가장 적은 것으로 나타났다. 4. 담체를 적용한 경우 슬러지중의 휘발성 고형분 함량이 일반 관행 폭기구에서 발생한 슬러지보다 더 낮아지는 결과를 보였다.