• Journal of Microbiology and Biotechnology
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• 제24권7호
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• pp.998-1003
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• 2014

Aspartate aminotransferase (AST; E.C. 2.6.1.1), a vitamin B6-dependent enzyme, preferentially promotes the mutual transformation of aspartate and ${\alpha}$-ketoglutarate to oxaloacetate and glutamate. It plays a key role in amino acid metabolism and has been widely recommended as a biomarker of liver and heart damage. Our study aimed to evaluate the extensive preparation of AST and its application in quality control in clinical laboratories. We describe a scheme to express and purify the 6His-AST fusion protein. An optimized sequence coding AST was synthesized and transformed into Escherichia coli BL21 (DE3) strain for protein expression. Ideally, the fusion protein has a volumetric productivity achieving 900 mg/l cultures. After affinity chromatography, the enzyme activity of purified AST reached 150,000 U/L. Commutability assessment between the engineered AST and standard AST from Roche suggested that the engineered AST was the better candidate for the reference material. Moreover, the AST showed high stability during long-term storage at $-20^{\circ}C$. In conclusion, the highly soluble 6His-tagged AST can become a convenient tool for supplying a much better and cheaper standard or reference material for the clinical laboratory.

• Composites Research
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• 제24권6호
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• pp.1-6
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• 2011

본 연구에서는 탄소나노튜브를 물상에서 균일하게 분산시키기 위하여 물에 녹으면서 분자 내에서 자체 도핑이 가능한 새로운 종류의 그래프트 공중합체(PSSA-g-PANI, poly(styrenesulfonic acid-graft-aniline))를 합성하였고, 그 분산 능력을 실험해 보았다. PANI 고분자는 벤조이드와 퀴노이드 구조가 반복되어 존재하는 판상구조로 탄소나노튜브와 같은 탄소나노 소재의 벽에 강하게 결합할 수 있고, 따라서 짧은 시간의 sonication 처리 만으로 나노튜브를 분산시킬 수 있었고 그 분산 용액의 장시간 안정성은 다른 상용화된 분산제보다 뛰어났다. 또한 PSSA-g-PANI 그래프트 고분자/탄소나노튜브 복합 필름은 대략 1.5-2.5 S/cm의 전도도를 기록하였다.

• 한국세라믹학회지
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• 제43권12호
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• pp.823-828
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• 2006

One of the main issues of Solid Oxide Fuel Cells (SOFCs) is to reduce the operating temperature to $750^{\circ}C$ or less. It has advantages of improving the life of component parts and the long-term stability of a system, so the production cost could be decreased. In order to achieve that, the ohmic and polarization loss of a single cell should be minimized first. This paper presents.to fabricate anode-supported single cells with controlling microstructure as a function of particle size and volume of graphite and NiO-YSZ weight ratio. By means of optimizing the manufactural condition through microstructure analysis and performance evaluation, the single cell which had NiO-YSZ=6:4, graphite volume of 24% and graphite size of $75{\mu}m$ as the anode composition showed a distinguished power density of $510mW/cm^2$ at $650^{\circ}C$ and $810mW/cm^2$ at $700^{\circ}C$, respectively.

• 청정기술
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• 제21권1호
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• pp.62-67
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• 2015

본 연구에서는 그래핀과 다중벽 탄소나노튜브를 포함하는 하이브리드 소재의 제조 및 슈퍼캐패시터 전극물질로의 활용에 관한 내용이 진행되었다. 이를 위하여 산화그래핀과 아민(-NH₂) 그룹이 치환된 다중벽 탄소나노튜브를 산 촉매 하에서 반응시켜, 새로운 이민(-C=N-) 결합이 도입된 하이브리드 복합체를 합성하였다. 상기 제조된 하이브리드 소재를 슈퍼캐패시터 전극 물질로 사용하고자 수산화칼륨 전해질 기반의 3상 전극 시스템을 활용하여 전기화학적 특성을 살펴보았다. 또한 하이브리드 소재에 존재하는 그래핀과 다중벽 탄소나노튜브의 비율 변화 실험을 통하여, 그래핀/탄소나노튜브의 질량비가 7.5/1일 때 그 특성이 최적화가 됨을 알 수 있었다. 최적화된 전극은 높은 비축천용량(132 F/g)을 나타내었을 뿐만 아니라, 반복된 충방전 실험에서 높은 안정성(95%, retention after 5000 cycles)을 나타내었다.

• 수산경영론집
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• 제47권1호
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• pp.87-100
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• 2016

Suhyup Bank became to be subject to regulation of capital ratio by Basel III which was introduced in order to enhance stability of the financial institution. Accordingly, Suhyup Bank will require recapitalization. It is important to estimate the risk-weighted assets in calculating of Suhyup Bank's recapitalization scale. Therefor, this study aimed to present a scientific model as estimated the risk-weighted assets. Risk-weighted assets are calculated by applying different risk weights for loans, may have a certain relationship with the loans. Results show that the risk-weighted assets is affected by the previous year's risk-weighted assets and influenced the increase in loans during the year. Since the required basic capital adequacy ratio was specified, the risk-weighted assets should be predicted reasonably. Accordingly, on this study it was tried to derive the accounting equation to predict the risk-weighted assets based on management data of a bank since introduction of Basel III. As the risk-weighted assets were weighted differently according to the type of loans, if the accounting equation is derived by using the type of loans, then it would be helpful for the risk management of banks in the long-term. According to this, the increase of loan would be predicted on the basis of past management performance of Suhyup Bank, and for this reason, the future risk-weighted assets of Suhyup Bank were predicted. The result of this study was showed that 98.3% of risk-weighted assets of the previous year, 62.4% of the secured loan changes and 95.1% of the credit loan changes affected risk-weighted assets.

• 대한기계학회논문집B
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• 제34권3호
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• pp.325-331
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• 2010

3-컵 풍속계는 자동기상측정, 환경 모니터링, 풍력 발전에 필요한 풍속을 측정하기 위해 널리 사용되고 있다. 일반적으로 3-컵 풍속계의 회전부를 지지하는 베어링은 오염물질, 진동 또는 돌풍 등의 여러 요인에 의해 마모되기 쉽고, 이로 인해 풍속에 대한 출력 특성이 장기적으로 변한다. 따라서 3-컵 풍속계를 주기적으로 교정하여 풍속에 대한 출력 특성을 유지 및 관리해야 한다. 본 연구에서는 3-컵 풍속계가 설치된 현장에서 풍속계를 교정 할 목적으로 제트 유동을 이용한 현장용 교정 장치를 제작하였다. 현장용 교정 장치가 3-컵 풍속계를 교정할 수 있는지 확인하기 위해, 현장용 교정 장치의 제트 유동 특성을 측정하였다. 현장용 교정 장치를 가지고 5 종류의 3-컵 풍속계들을 교정하였고, 풍동에서 3-컵 풍속계를 교정한 결과와 비교하였다.

• 한국동물학회지
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• 제39권1호
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• pp.75-88
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• 1996

OTF9-63 (OTF9)와 P19S1O1A1 (P19) 배종양 세포들의 체세포에 존재하는 불화성 X 염색체의 재활성과 유발 능력을 조사하였다. 배종야 세포와 체세포들의 융합에 의해 얻어진 HATr 클론들의 형태, 염색체 복제 양상을 비롯하여 X 염색체에 존재하나 그 위치는 상당히 먼 유전자들인 Hprt와 Pgk-1의 발현 양상을 분석한 결과, OTF9 세포는 불활성 X 염색체를 재활성화 시킬 수 있는데 반해 P19 세포는 불가능한 것으로 나타났다. 또한, 모든 유합세포는 장기간 배양되었을 때 성염색체의 수가 감소하였으며, 결국 1:2의 성염색체:상염색체의 비율을 나타내었다. 배종양 세포-체세포 융합세포의 이용은 초기 배발생 과정에서 시작되어 난자형성 과정의 감수분열 전까지의 유지되는 X 념색체의 재활성화 기작을 연구하기 위한 실험 방법을 제공한다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제34권4호
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• pp.468-474
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• 2008

Purpose: Previous clinical investigations of sinus floor augmentation have demonstrated repneumatization of grafted sinus. The aim of this study is to evaluate and compare the height changes of sinus floor after grafting with deprotenized bovine bone mineral (DBBM) and beta tricalcium phosphate (TCP). Materials and methods: 34 sinuses in 28 patients were augmented with 100% DBBM or 100% TCP through lateral approaches. Sinusgraft height was measured before, immediately after, and 6 months after bone graft with panoramic radiography. Result: After 6 months, the decreases of graft heights were 14.53% for DBBM group and 15.15% for TCP group. There was no statistically significant difference. Discussion and Conclusion: Long-term stability of sinus-graft height represents an important factor for implant success. After the uses of DBBM and TCP for maxillary sinus floor augmentations, acceptable graft height maintenances were observed.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.193-197
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• 2002

The tribological properties and van der Waals attractive forces and the thermal stability of films are very important characteristics of highly hydrophobic fluorocarbon (FC) films for the long-term reliability of nano system. The effect of thermal annealing on films and van der Waals attractive forces and friction coefficient of films have been investigate d in this study. It was coated Al wafer which was treated O2 and Ar that ocatfluorocyclobutane ($C_4_{8}$) and Ar were supplied to the CVD chamber in the ratio of 2:3 for deposition of FC Films. Static contact angle and dynamic contact angle were used to characterize FC films. Thickness of films was measured by variable angle spectroscopy ellipsometer (VASE). Nanotribological data was got by atomic force microscopy (AFM) to measure roughness, lateral force microscopy (LFM) to measure friction force, and force vs. distance (FD) curve to evaluate adhesion force. FC films were cured in N2 and vacuum. The film showed the slight changes in its properties after 3 hr annealing. FTIR ATR studies showed the decrease of C-F peak intensity in the spectra as the annealing time increased. A significant decrease of film thickness has been observed. The friction force of Al surface was at least thirty times higher than ones with FC films. The adhesive force of bare Al was greater than 100 nN. After deposit FC films adhesive force was decreased to 40 nN. The adhesive force of films was decreased down to 10 nN after 24 hr annealing. During 24 hr annealing in $N_2$and vacuum at $100^{\circ}C$ film properties were not changed so much.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.151-159
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• 2015

PURPOSE. To describe and characterize the surface topography and cleanliness of CAD/CAM manufactured zirconia abutments after steaming and ultrasonic cleaning. MATERIALS AND METHODS. A total of 12 ceramic CAD/CAM implant abutments of various manufacturers were produced and randomly divided into two groups of six samples each (control and test group). Four two-piece hybrid abutments and two one-piece abutments made of zirconium-dioxide were assessed per each group. In the control group, cleaning by steam was performed. The test group underwent an ultrasonic cleaning procedure with acetone, ethyl alcohol and antibacterial solution. Groups were subjected to scanning electron microscope (SEM) analysis and Energy-dispersive X-ray spectroscopy (EDX) to verify and characterize contaminant chemical characterization non- quantitatively. RESULTS. All zirconia CAD/CAM abutments in the present study displayed production-induced wear particles, debris as well as organic and inorganic contaminants. The abutments of the test group showed reduction of surface contamination after undergoing an ultrasonic cleaning procedure. However, an absolute removal of pollutants could not be achieved. CONCLUSION. The presence of debris on the transmucosal surface of CAD/CAM zirconia abutments of various manufacturers was confirmed. Within the limits of the study design, the results suggest that a defined ultrasonic cleaning process can be advantageously employed to reduce such debris, thus, supposedly enhancing soft tissue healing. Although the adverse long-term influence of abutment contamination on the biological stability of peri-implant tissues has been evidenced, a standardized and validated polishing and cleaning protocol still has to be implemented.