• Smart Structures and Systems
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• 제25권5호
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• pp.543-557
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• 2020

This paper presents a series of experimental and numerical investigations on a vertical isolation system with quasi-zero stiffness (QZS) property. The isolation system comprises a linear helical spring and disk spring. The disk spring is designed to provide variable stiffness to the system. Orthogonal static tests with different design parameters are conducted to verify the mathematical and mechanical models of the isolation system. The deviations between theoretical and test results influenced by the design parameters are summarized. Then, the dynamic tests for the systems with different under-load degrees are performed, including the fast sweeping tests, harmonic excitation tests, and half-sine impact tests. The displacement transmissibility, vibration reduction rate, and free vibration response are calculated. Based on the test results, the variation of the transmission rule is evaluated and the damping magnitudes and types are identified. In addition, the relevant numerical time history responses are calculated considering the nonlinear behavior of the system. The results indicate that the QZS isolation system has a satisfactory isolation effect, while a higher damping level can potentially promote the isolation performance in the low-frequency range. It is also proved that the numerical calculation method accurately predicts the transmission character of the isolation system.

• BMB Reports
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• 제44권1호
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• pp.1-10
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• 2011

Inter-cellular communication via diffusible small molecules is a defining character not only of multicellular forms of life but also of single-celled organisms. A large number of bacterial genes are regulated by the change of chemical milieu mediated by the local population density of its own species or others. The cell density-dependent "autoinducer" molecules regulate the expression of those genes involved in genetic competence, biofilm formation and persistence, virulence, sporulation, bioluminescence, antibiotic production, and many others. Recent innovations in recombinant DNA technology and micro-/nano-fluidics systems render the genetic circuitry responsible for cell-to-cell communication feasible to and malleable via synthetic biological approaches. Here we review the current understanding of the molecular biology of bacterial intercellular communication and the novel experimental protocols and platforms used to investigate this phenomenon. A particular emphasis is given to the genetic regulatory circuits that provide the standard building blocks which constitute the syntax of the biochemical communication network. Thus, this review gives focus to the engineering principles necessary for rewiring bacterial chemo-communication for various applications, ranging from population-level gene expression control to the study of host-pathogen interactions.

• 한국한의학연구원논문집
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• 제9권1호
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• pp.51-63
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• 2003

The international government committee is progressing their agreements about intellectual property protection of traditional knowledge(TK), gene resource(GR), folklore(FL) in WIPO. It is in the course of selection with precedence of TK, GR, FL in WlPO, focused on discussions about listing of TK documents, standardization of DB construction, sharing and profit distribution of GR. Their are disagreements between developed countries and underdeveloped countries about intellectual property protection agreements of TK, GR. The developed countries insist on using, the existing intellectual property protections, but the underdeveloped countries ask new ones on character of TK, GR, It causes intangible assets to be valuable trade properties in future world trade. We have to make national plans to face agreements about IP of TK, GR in WIPO with our own TK, GR. We must have a basic attitude about laying down these plans such as raising national economy, considering our TK, GR to be relics of mankind culture. In addition to these, it needs accurate analysis about agreements in WIPO, our TK, GR, scientific mechanical level and capital power.

• 한국실내디자인학회논문집
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• 제19권3호
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• pp.234-241
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• 2010

Avoiding the unified productivity that was caused by the mechanical and technical development due to Industrial Revolution in the past, modern design is incessantly evolving in search of new motive, namely, diversity. Further, we live in the age when the propensity that serves public interest and purpose and sometimes shows quite individual character should be considered. As a result, the comprehensive and harmonious trend of emotional design is being highlighted more remarkably. Involving the social background that further respects human dignity, this is closely related to diverse issues such as human right which should be guaranteed and pursued for individual. While the tradition and innovation caused by the encounter of machine and art had confrontation and conflict in the past, the direction has changed to incessant evolution and interaction where paradigm of technical progress and development is newly composed and changed in modern times. The meaning of service in medical area is expanding and developing from the simple treatment to the more comprehensive healing. Medical space will evolve to the healing space that attaches importance to emotional aspect of human dimension which further understands and respects human being in the future.

• Steel and Composite Structures
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• 제34권4호
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• pp.561-580
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• 2020

Buckling restrained braces (BRBs) were developed as an enhanced alternative to conventional braces by restraining their global buckling, thus allowing development of a stable quasi-symmetric hysteretic response. A wider adoption of buckling restrained braced frames is precluded due to proprietary character of most BRBs and the code requirement for experimental qualification. To overcome these problems, BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were developed and experimentally tested in view of prequalification. In the second part of this paper, a complex nonlinear numerical model for the tested BRBs was developed in the finite element environment Abaqus. The calibration of the numerical model was performed at both component (material models: steel, concrete, unbonding material) and member levels (loading, geometrical imperfections). Geometrically and materially nonlinear analyses including imperfections were performed on buckling restrained braces models under cyclic loading. The calibrated models were further used to perform a parametric study aiming at assessing the influence of the strength of the buckling restraining mechanism, concrete class of the infill material, mechanical properties of steel used for the core, self-weight loading, and frame effect on the cyclic response of buckling restrained braces.

• 한국태양에너지학회 논문집
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• 제34권5호
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• pp.53-63
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• 2014

Caltech's Linde-Robinson Laboratory was originally built in 1932 featuring a Spanish mission-style design, whose function was to facilitate a solar observatory with a coelostat solar telescope dome and a solar shaft extending from the roof to more than 36.58m below the ground. The building has now been transformed into a cutting-edge center for research and instruction in global environmental science that retains its original character while setting new standards in energy efficiency and green design. It is the first LEED Platinum lab in the USA for renovation of a historical research building, consuming only one-sixth of the energy that the lab's comparable laboratories do. This work introduces various energy and environmental strategies hired for its sustainable rehabilitation and, especially, examines the functional validity of solar telescope daylighting by a coelostat. Observations were made on the llumination of underground floors, where illuminances of 40~50 lx were measured.

• Macromolecular Research
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• 제10권4호
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• pp.187-193
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• 2002

Several methods have been used to synthesize polymer-clay nanocomposites. In-situ polymerization with clay belongs to a classical way to develop nano-structured materials, while melt intercalation is being recognized as another useful approach due to its versatility and environmentally benign character. In this research, we prepared polymer-clay nanocomposites based on the poly (methyl methacrylate) and organically modified montmorillonite via two-stage sonication process. According to the unique mode of power ultrasonic wave, the sonication during processing led to enhanced breakup of the clay agglomerates and reduction in size of the dispersed phase. Optimum conditions to form stable exfoliated nanocomposites were studied for various compositions and conditions. It was found that a novel attempt carried out in this study yielded further improvement in the mechanical performance of the nanocomposites compared to those produced by the conventional melt mixing process, as revealed by DMA, XRD and TEM. And rheological properties of nanocomposites were measured by ARES. As a result, sonicated PMMA-clay nanocomposites exhibits enhanced properties such as storage modulus and thermal stability than that of neat PMMA.

• 한국전기전자재료학회논문지
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• 제16권8호
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• pp.700-704
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• 2003

This paper describes on characteristics of 2" 3C-SiC wafer bonding using PECVD (plasma enhanced chemical vapor deposition) oxide and HF (hydrofluoride acid) for SiCOI (SiC-on-Insulator) structures and MEMS (micro-electro-mechanical system) applications. In this work, insulator layers were formed on a heteroepitaxial 3C-SiC film grown on a Si (001) wafer by thermal wet oxidation and PECVD process, successively. The pre-bonding of two polished PECVD oxide layers made the surface activation in HF and bonded under applied pressure. The bonding characteristics were evaluated by the effect of HF concentration used in the surface treatment on the roughness of the oxide and pre-bonding strength. Hydrophilic character of the oxidized 3C-SiC film surface was investigated by ATR-FTIR (attenuated total reflection Fourier transformed infrared spectroscopy). The root-mean-square suface roughness of the oxidized SiC layers was measured by AFM (atomic force microscope). The strength of the bond was measured by tensile strength meter. The bonded interface was also analyzed by IR camera and SEM (scanning electron microscope), and there are no bubbles or cavities in the bonding interface. The bonding strength initially increases with increasing HF concentration and reaches the maximum value at 2.0 ％ and then decreases. These results indicate that the 3C-SiC wafer direct bonding technique will offers significant advantages in the harsh MEMS applications.ions.

• 동아시아식생활학회지
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• 제6권1호
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• pp.69-76
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• 1996

This study examined the distinctive character and level of preference of SsookGae-Dduck which was produced with making 2, 3, 4, 5% of difference, adding 30% mugwort. In the sensory evaluation for SsookGae-Dduck, the bitterness, hardness and flavor were highly evaluated as the amount of mugwort powder was increasing. The sweetness and color showed the highest number in the adding group of 2% mugwort powder. In the being moistness degree, the 30% adding group of mugwort was the highest one, and 3% adding group in the mugwort powder. And the chewiness was highly marked in the adding group of 30% mugwort, and 5% adding group was highly marked in the mugwort powder. In the mechanical evaluation of SsookGae-Dduck, the hardness and adhesiveness were highly marked in the adding group of 5% mugwort powder, the adding group of 4% showed the highest number in the springiness, cohesiveness, gumminess and chewiness. Through these all studies, the mugwort powder should be used in the multi way of our food life and it was really necessary to be studies and to be taken interest in this area constantly.

• Wind and Structures
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• 제4권4호
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• pp.333-352
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• 2001

A two dimensional discrete vortex method (DIVEX) has been developed to predict unsteady and incompressible flow fields around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow field that the particles collectively induce. This paper gives a brief description of the numerical implementation of DIVEX and presents the results of calculations on a recent suspension bridge deck section. The predictions for the static section demonstrate that the method captures the character of the flow field at different angles of incidence. In addition, flutter derivatives are obtained from simulations of the flow field around the section undergoing vertical and torsional oscillatory motion. The subsequent predictions of the critical flutter velocity compare well with those from both experiment and other computations. A brief study of the effect of flow control vanes on the aeroelastic stability of the bridge is also presented and the results from DIVEX are shown to be in accordance with previous analytical and experimental studies. In conclusion, the results indicate that DIVEX is a very useful design tool in the field of wind engineering.