• Journal of Microbiology and Biotechnology
• /
• 제22권6호
• /
• pp.793-799
• /
• 2012

A gene related to high pristinamycin yield in Streptomyces pristinaespiralis was selected by amplified fragment length polymorphism (AFLP) and its functions were investigated by gene disruption. First, a 561 bp polymorphic sequence was acquired by AFLP from high-yield recombinants compared with the S. pristinaespiralis ancestor ATCC25486, indicating that this approach is an effective means of screening for valuable genes responsible for antibiotic yield. Then, a 2,127 bp open reading frame of a gene designated spy1 that overlaps with the above fragment was identified and its structure and biological functions were investigated. In silico analysis of spy1 encoding a deduced 708-amino-acid-long serine/threonine protein kinase showed that it only contains a catalytic domain in the N-terminal region, which is different from some known homologs. Gene inactivation of chromosomal spy1 indicated that it plays a pleiotropic regulatory function in pristinamycin production, with a positive correlation to pristinamycin I biosynthesis and a negative correlation to pristinamycin II biosynthesis.

• Structural Engineering and Mechanics
• /
• 제33권6호
• /
• pp.675-696
• /
• 2009

In this paper, a unified solution method is presented for the classical beam theory. In Strength of Materials approach, the geometry, material properties and load system are known and related with the unknowns of forces, moments, slopes and deformations by applying a classical differential analysis in addition to equilibrium, constitutive, and kinematic laws. All these relations are expressed in a unified formulation for the classical beam theory. In the special case of simple beams, a system of four linear ordinary differential equations of first order represents the general mechanical behaviour of a straight beam. These equations are solved using the numerical differential quadrature method (DQM). The application of DQM has the advantages of mathematical consistency and conceptual simplicity. The numerical procedure is simple and gives clear understanding. This systematic way of obtaining influence line, bending moment, shear force diagrams and deformed shape for the beams with geometric and load discontinuities has been discussed in this paper. Buckling loads and natural frequencies of any beam prismatic or non-prismatic with any type of support conditions can be evaluated with ease.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2010년도 정기 학술대회
• /
• pp.620-623
• /
• 2010

구조요소의 설계에서 유한요소해석은 매우 효과적인 방법이며 정확한 해석 기술을 요구한다. 그러나 제조 공정이나 환경에 따라 달라지는 재료 물성이나 불확실성을 내포하는 피로 물성을 확정적인 값으로 이용하는 등 입력 변수의 부정확한 정보로 인해 유한요소해석 결과를 신뢰하지 못하는 경우가 자주 발생한다. 실제 시험을 통해 설계의 결과를 예측하는 것은 경제적인 측면과 시간소요 면에서 한계가 따르기에 신뢰할 수 있는 유한요소해석 방법이 요구된다. 본 연구에서는 고주기의 피로 해석을 위해 유한요소해석을 이용하여 스프링의 응력-수명(S-N) 파라미터를 역 추정하고 수명을 예측해 보았다. 이를 위해 실제 산업현장에서 쓰이는 자동차 서스펜션 코일 스프링을 예제로 사용하였다. 시험 모델에 대해 불확실성을 고려한 베이지안 접근법을 이용하여 입력변수의 파라미터를 역 추정하였으며, 마코프체인몬테카를로(Markov Chain Monte Carlo) 기법을 이용하여 얻어진 피로 물성 파라미터의 샘플 데이터를 이용해서 유한요소해석을 실시하고 신뢰수준 내에서 새로운 구조요소의 피로수명을 예측하였다.

• Journal of Microbiology and Biotechnology
• /
• 제21권11호
• /
• pp.1123-1126
• /
• 2011

The IncP plasmid R995 has been a useful self-transmissible, broad-host-range vector for a number of applications including the recombinase/conjugation-based cloning of large genomic DNA segments. However, R995 derivatives (or related plasmids) expressing a wide range of different resistance markers and Flp recombinase target sites do not exist in the literature. In addition, documented strategies for applying such plasmids in cloning applications that take advantage of conjugation for the convenient isolation and recovery of constructs are extremely limited. Here, we report a new series of R995 plasmids with alternative markers to increase options for applications in backgrounds already expressing resistance to a particular antibiotic(s). These R995 plasmids have been engineered to contain FRT sites that can be used for recombinase-based cloning. We demonstrate the utility of this approach by cloning 20 kb regions from the Salmonella Typhimurium and Escherichia coli genomes and by cloning DNA from an exogenous plasmid source. To our knowledge, this represents the first systematic engineering of an intact, self-transmissible IncP plasmid with a series of alternative antibiotic markers and FRT sites.

• 한국방송∙미디어공학회:학술대회논문집
• /
• 한국방송공학회 1999년도 KOBA 방송기술 워크샵 KOBA Broadcasting Technology Workshop
• /
• pp.119-124
• /
• 1999

This paper proposes an evolutionary model for automatically generating artificial creatures of various shapes and colors according to insect ecology. This model offers a novel way to naturally evolve the shapes and colors of artificial creatures. The evolutionary model used in our research is based on Genetic Algorithms (GA). In this paper, artificial Computer Graphics(CG) creatures develop into various shapes and colors according to the evolutionary model. Later, they can be used as CG animated characters. This model also solves the problem of reducing the time and labor cost for mass production of various characters. It could be used in such areas as the cavalry battle scene in Disney's animation, “Mulan”. Our approach has two steps. At first, artificial creatures move according to information gathered form the five senses. This information is also used for generating the shapes of the five sense organs[1]. Then, based on the GA, evolutionary mode[2], we prepare prototype creatures, which evolve into various shapes and different colors in alternating generations. Finally, our evolutionary model successfully generates various character shapes and colors automatically.

• Journal of Welding and Joining
• /
• 제31권6호
• /
• pp.32-36
• /
• 2013

The large-scale structures have the possibility that there are defects such as cracks due to stress concentration caused by geometric discontinuities in the structure. In this respect, the assessment of fatigue life and the development of structural health monitoring(SHM) are very important. Fatigue design of structure is typically accomplished either using a set of stress cycle (S-N) data obtained from fatigue tests or using the fracture mechanics approach. The stress intensity factor(SIF) is required for the estimation of fatigue crack propagation life from the linear elastic fracture mechanics (LEFM) perspective. In this study, Macro Fiber Composie(MFC) sensor for the measurement of SIF of two dimensional cracks is used. The SIF based on the piezoelectric constitutive law and fracture mechanics are calculated. The measured values of the SIF are later used for the prediction of the crack propagation life. In this study, the measured value of the SIF and the fatigue life are compared with the theoretical results.

• Journal of Theoretical and Applied Mechanics
• /
• 제1권1호
• /
• pp.97-109
• /
• 1995

In this paper, a finite viscoelastic continuum model for rubber and its finite element analysis are presented. This finite viscoelatic model based on continuum mechanics is an extended model of Johnson and Wuigley's 1-D model. In this extended model, continuum based kinematic measures are rigorously defied and by using this kinematic measures, elastic stage law and flow rule are introduced. In kinematics, three configuration are introduced. In kinematics, three configuration are introduced. They are reference, current and virtual visco configurations. In elastic state law, it is assumed that at a certain time, there exists an elastic potential which describes the recoverable elastic energy. From this elastic potential, elastic state law is derived. The proposed flow rule is based on phenomenological observation. The flow rule gives precise relaxation response. In finite element approximation, mixed Lagrangian description is used, where total and similar method of updated Lagrangian descriptions are used together. This approach reduces the numerical job and gives simple nonlinear syatem of equations. To satisfy the incompressible condition, penalty-type modified Mooney-Rivlin energy function is adopted. By this method nearly incompressible condition is obtain the virtual visco configuration. For verification, uniaxial stretch tests are simulated for various stretch rates. The simulated results show good agreement with experiments. As a practical experiments. As a preactical example, pressurized rubber plate is simulated. The result shows finite viscoelastic effects clearly.

• Advances in nano research
• /
• 제5권2호
• /
• pp.69-97
• /
• 2017

In this study, nonlinear response of laminated functionally graded carbon nanotube reinforced composite (FG-CNTRC) plate under low-velocity impact based on the Eshelby-Mori-Tanaka approach in thermal conditions is studied. The governing equations are derived based on higher-order shear deformation plate theory (HSDT) under von $K\acute{a}rm\acute{a}n$ geometrical nonlinearity assumptions. The finite element method with 15 DOF at each node and Newmark's numerical integration method is applied to solve the governing equations. Four types of distributions of the uniaxially aligned reinforcement material through the thickness of the plates are considered. Material properties of the CNT and matrix are assumed to be temperature dependent. Contact force between the impactor and the laminated plate is obtained with the aid of the modified nonlinear Hertzian contact law models. In the numerical example, the effect of layup (stacking sequence) and lamination angle as well as the effect of temperature variations, distribution of CNTs, volume fraction of the CNTs, the mass and the velocity of the impactor in a constant energy level and boundary conditions on the impact response of the CNTRC laminated plates are investigated in details.

• Food Science and Biotechnology
• /
• 제27권6호
• /
• pp.1857-1864
• /
• 2018

Phthalate plasticizers residue in food is a serious threat to public health. Spores of Ganoderma lucidum are easy to be contaminated with phthalates during collection and processing. In this study, supercritical fluid extraction (SFE) was performed to remove phthalates in spores of G. lucidum, and the effects on acid and peroxide values of spores' oil were also evaluated. The results showed SFE removed 100% of the residual di-iso-butyl phthalate, di-n-butyl phthalate and di-2-ethylhexyl phthalate in the spores of G. lucidum. No significant differences in polysaccharides content and fatty acid composition were observed between SFE and control spores. However, the triterpenoid extracts of SFE spores had a 7.45% increase, significantly higher than that in control spores. Accelerated oxidation tests further implied that SFE could improve the stability of spores' oil. Our results suggested SFE is a potential approach to remove phthalate from food related products.

• Bulletin of the Korean Chemical Society
• /
• 제22권7호
• /
• pp.709-715
• /
• 2001

We have been studied photosensitization mechanism's additive effect, of perylene 3,4,9,10-tetracarboxyl-diimide and X-phthalocyanine (charge generation materials), using the photochemical and photoelectrochemical approach. It was found that the photoreceptor on the excited state reacts with metal oxide, which creates the charge transfer on the interface of SnO2/electrolyte. In the electrode (X5P1) made of five X-phthalocyanine and single perylene 3,4,9,10-tetracarboxyldiimide layers, the cathodic photocurrent of X-phthalocyanine in the 400-600 nm region was increased by the addition of perylene 3,4,9,10-tetracarboxyldiimide. The maximum wavelength of fluorescence of perylene 3,4,9,10-tetracarboxyldiimide showed no dependence on the temperature. The addition of 4-dibenzylamino-2-methylbenzaldehyde diphenylhydrazone known as charge transport material was represented as decreasing photocurrent for X-phthalocyanine and perylene 3,4,9,10-tetracarboxyldiimide, respectively. In the electrode (X1P1) made of single X-phthalocyanine and single perylene 3,4,9,10-tetracarboxyldiimide layers, an anodic photocurrent of about 10.5 nA was generated by addition of hydroquinone at 550 nm. And the characteristic of photoinduced discharge was shown to decrease by a factor of 5 and the speed of dark decay was increased by a factor of 1.2.