• 한국미생물·생명공학회지
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• 제39권2호
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• pp.140-145
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• 2011

돼지유행성설사 바이러스(porcine epidemic diarrhea virus: PEDV)는 자돈에게 감염 시 수양성설사를 동반한 급성 장염을 유발하며 매우 높은 폐사율을 보이는 그룹 1 코로나바이러스이다. PEDV는 다른 그룹 1 코로나바이러스와 마찬가지로 숙주 세포에 감염 시 aminopeptidase N (APN)을 세포 수용체로 이용한다고 알려져 있다. 코로나바이러스의 spike(S) 단백질은 숙주세포의 표면에 부착과 관련하여 감염 개시에 있어 중요한 역할을 하는 것으로 알려져 있으며 특히 S 단백질의 S1 도메인은 세포 수용체에 특이적인 결합을 매개하는 수용체 결합 도메인(receptor binding domain: RBD)을 포함하고 있는 것으로 알려져 있다. 이미 많은 코로나바이러스의 RBD의 위치가 확인되어져 있지만 PEDV의 RBD에 대해서는 아직까지 알려진 바가 없다. 본 연구에서는 돼지 APN 수용체와 결합을 매개하는 PEDV의 RBD를 규명하기 위해 S1 도메인을 주형으로 하는 일련의 재조합 truncated variant들을 제작하였고 각각의 truncated들이 실제로 pAPN과의 결합을 이루는지에 대하여 실험을 통해 확인하였다. 그 결과 S1 도메인의 N 말단 부분이 pAPN과의 결합에서 중요한 부위임을 확인할 수 있었다. 본 연구에서 도출된 결과는 향후 PEDV의 S 단백질과 pAPN간의 분자적 상호작용을 이해하는 데에 도움을 줄 것으로 판단된다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1996년도 학술대회
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• pp.223-227
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• 1996

In this paper we propose an adaptive fast image restoration filter, which is suitable for reducing the blocking artifacts in the compressed image in real-time. The proposed restoration filter is based on the observation that quantization operation in a series of coding process is a nonlinear and many-to-one mapping operator. And then we propose an approximated version of constrained optimization technique as a restoration process for removing the nonlinear and space varying degradation operator. We also propose a novel block classification method for adaptively choosing the direction of a highpass filter, which serves as a constraint in the optimization process. The proposed classification method adopts the bias-corrected maximized likelihood, which is used to determine the number of regions in the image for the unsupervised segmentation. The proposed restoration filter can be realized either in the discrete Fourier transform domain or in the spatial domain in the form of a truncated finite impulse response (FIR) filter structure for real-time processing. In order to demonstrate the validity of the proposed restoration filter experimental results will be shown.

• Steel and Composite Structures
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• 제22권2호
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• pp.301-321
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• 2016

The objective of this paper is to investigate buckling behavior of composite laminated cylinders by using semi-analytical finite strip method. The shell is subjected to deformation-dependent loads which remain normal to the shell middle surface throughout the deformation process. The load stiffness matrix, which is responsible for variation of load direction, is also throughout the deformation process. The shell is divided into several closed strips with alignment of their nodal lines in the circumferential direction. The governing equations are derived based on the first-order shear deformation theory with Sanders-type of kinematic nonlinearity. Displacements and rotations of the shell middle surface are approximated by combining polynomial functions in the meridional direction and truncated Fourier series along with an appropriate number of harmonic terms in the circumferential direction. The load stiffness matrix, which is responsible for variation of load direction, is also derived for each strip and after assembling, global load stiffness matrix of the shell is formed. The numerical illustrations concern the pressure stiffness effect on buckling pressure under various conditions. The results indicate that considering pressure stiffness causes buckling pressure reduction which in turn depends on various parameters such as geometry and lay-ups of the shell.

• Journal of Microbiology and Biotechnology
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• 제8권1호
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• pp.42-48
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• 1998

In order to maximize the secretory expression of human serum albumin (HSA) in the yeast Saccharomyces cerevisiae, a series of HSA expression vectors were constructed with a combination of different promoters, 5' untranslated regions (5'UTR), and secretion signal sequences. The expression vector composed of the galactose-inducible promoter GALl0, the natural 5'UTR, and the natural signal sequence of HSA directed the most efficient expression and secretion of HSA among the constructed vectors when introduced into several S. cerevisiae strains. Although the major form of HSA expressed and secreted in the yeast transformants was the mature form of 66 kDa, the truncated form of 45 kDa was also detected both in the cell extract and in the culture supernatant. The level of the intact HSA protein in the culture supernatant reached up to 30 mg/l at 24 h of cultivation in a shake-flask culture but began to decrease afterwards, indicating that the secreted HSA protein was unstable in a prolonged culture of yeast.

• 설비공학논문집
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• 제19권6호
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• pp.457-463
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• 2007

Various correlations of saturated vapor density in a truncated power series form are tested and compared in this study. Saturated vapor density correlation can be expressed relating logarithmic reduced density to the reduced temperature. Five types of correlation has been investigated using saturated vapor density data for 22 pure substance refrigerants from ASHRAE (American Society of Heating, Reftigerating and Air-Conditioning Engineers, Inc.) property tables and NIST (National Institute of Standards and Technology) Chemistry Webbook. Correlations are fitted to the data points by least squares method. Data points are equally weighted. The best type of correlation among the five types is suggested. The results obtained indicate that the best correlations with 3, 4, and 5 terms yield average AAD's (Average Absolute Deviation) of 0.27%, 0.04%, and 0.02%, respectively, while widely used conventional correlations with 3, 4, and 5 terms yield those of 1.19%, 0.61%, and 0.17%. The suggested type of correlation could reduce the number of terms while improving performance.

• KSBB Journal
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• 제7권3호
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• pp.201-208
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• 1992

일부의 EGF receptor 에는 EGF 가 세포표면에서 receptor 와 결합할 때 보다 높은 친화력(high affinity)을 보이고 있는데 그 이유를 설명하기 위해서 EGF receptor 의 cytoplasmic 영역을 절단하여 EGF 와의 친화력을 측정하였다. Scatchard plot 의 결과 1022 아미노산 이하로 절단된 receptor 는 high affinity 특성을 상실하였다. Triton X-100로 세포막을 제거하여 cytoskeleton 이 EGF receptor 의 구조에 미치는 영향을 조사한 결과 cytoskeleton과 결합한 receptor 보다 EGF 에 대해서 더 높은 친화력을 보였다. 따라서 cytoskeleton 이 high affinity EGF receptor 를 형성하는데 영향을 미치고 receptor 와 cytoskeleton 의 가능한 결합부위는 1022-1186 아미노산 사이인 것 같다.

• 한국레이저가공학회지
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• 제14권2호
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• pp.24-29
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• 2011

The design of a telecentric f-${\theta}$ lens with a field of view (FOV) $30^{\circ}$ and an effective focal length of 1000mm is presented. The optical stop is placed at the front plane and the design is based on a geometric ray tracing technique, and the designed system consists of a series of convex and concave lenses. The designed f-${\theta}$ lens showed a considerable reduction in weight with a simplified structure and resulted in a good performance in the designated FOV. Detail analysis of rays is also presented. 653nm (red laser), 586nm (green laser), and 468nm (blue laser) were simulated as a light source and image illuminating source. The developed optical design requires 7 pieces of lenses made of SF1, N-FK56, N-LAK33, and BK7 glass materials. With optimal parametric design, the effective focal length was calculated to be 974.839mm which is very close to the initial design target. For the manufacturing purpose, the dimensions of lens curvature and thickness were truncated with error ranging 0.1% to 3.2%. As a result, the overall error was calculated to be 3.2% which can be still tolerable for display, laser material, and machining processing.

• Wind and Structures
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• 제13권3호
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• pp.235-256
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• 2010

The aeroelastic stability of bridge decks equipped with multiple tuned mass dampers is studied. The problem is attacked in the time domain, by representing self-excited loads with the aid of aerodynamic indicial functions approximated by truncated series of exponential filters. This approach allows to reduce the aeroelastic stability analysis in the form of a direct eigenvalue problem, by introducing an additional state variable for each exponential term adopted in the approximation of indicial functions. A general probabilistic framework for the optimal robust design of multiple tuned mass dampers is proposed, in which all possible sources of uncertainties can be accounted for. For the purposes of this study, the method is also simplified in a form which requires a lower computational effort and it is then applied to a general case study in order to analyze the control effectiveness of regular and irregular multiple tuned mass dampers. A special care is devoted to mistuning effects caused by random variations of the target frequency. Regular multiple tuned mass dampers are seen to improve both control effectiveness and robustness with respect to single tuned mass dampers. However, those devices exhibit an asymmetric behavior with respect to frequency mistuning, which may weaken their feasibility for technical applications. In order to overcome this drawback, an irregular multiple tuned mass damper is conceived which is based on unequal mass distribution. The optimal design of this device is finally pursued via a full domain search, which evidences a remarkable robustness against frequency mistuning, in the sense of the simplified design approach.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.317-317
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• 2010

This paper reports syntheses of $TiO_2$ nanocubes and theirs application to DSSC. We synthesized $TiO_2$ nanocubes via solvothermal method using titanium isopropoxide (TTIP) and tetramethylammoiumhydroxide (TMAH). By adding longer alkyl chain ammonium hydroxide that slowed down the growth rate of the crystal, $TiO_2$ nanocubes were obtained with average particle size in the range of 40 nm to 70 nm. By TEM investigation, each particle was found to be single crystal of anatase having six-faces of (001) and {100} crystallographic planes truncated by {101} series of planes, which are clearly distinguishable from spherical nanoparticles. Among various application, utilizing nanocubes as photo-electrode in dye-sensitized solar cell, we investigated photo-electron conversion performances in comparison with spherical shaped $TiO_2$ nanoparticles by I-V characteristics and IPCE measurements, etc.. Photocurrent-transient analysis revealed that $TiO_2$ nanocubes have a higher transient electron transfer rate by more than 10 times compared with spherical particles of similar size. Fast electron transport along the cube edges having small curvature was suggested as a plausible origin of high diffusion coefficient of electron in nanocube $TiO_2$.

• 한국전산구조공학회논문집
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• 제28권2호
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• pp.123-130
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• 2015

본 논문에서는 전자기파에 대한 수치적 파동흡수 경계모델인 Perfectly-Matched-Layer(PML)를 개발하고 PML을 연동시킨 유한요소법에 의해 콘크리트 구조물을 통과하는 마이크로파의 전파거동을 해석하는 수치적 기법을 제시한다. 콘크리트 부재와 공기로 구성된 무한매질을 PML을 경계로 하는 유한영역으로 치환하고, 이 유한영역에서 평면 전자기파에 대한 시간 영역 맥스웰방정식의 수치 해를 혼합유한요소법에 의해 계산하였다. 공기로만 이루어진 균일매질의 경우와 콘크리트 구조물이 존재하는 비균일 매질의 경우에 대하여 단일주파수 및 복합주파수를 갖는 마이크로파의 전기장을 계산하였고, 오차분석을 위해 $L^2$-놈 형태로 표현되는 정해와 수치 해의 상대오차를 정의하여 수치 해의 정확도를 평가하였다. 이 연구는 마이크로파를 이용한 철근콘크리트 구조물의 건전도평가 및 손상평가에 적용될 수 있다.