• International Journal of Aeronautical and Space Sciences
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• 제15권2호
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• pp.113-122
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• 2014

The objective of the paper is to clarify a methodology based on the use of the existing component mode synthesis methods for the case of two damped substructures which are coupled through a linking viscoelastic flexible substructure and for which the structural modes with free geometrical interface are used for each main substructure. The proposed methodology corresponds to a convenient alternative to the direct use either of the Craig-Bampton method applied to the three substructures (using the fixed geometric interface modes) or of the flexibility residual approaches initiated by MacNeal (using the free geometric interface modes). In opposite to a geometrical interface which is a topological interface on which there is a direct linkage between the degrees of freedom of substructures, we consider a physical flexible interface which exists in certain present technologies and for which the general framework linear viscoelasticity is used and yields a frequency-dependent damping and stiffness matrices of the physical flexible interface.

• 대한기계학회논문집A
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• 제24권6호
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• pp.1427-1437
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• 2000

In the authors＇ preceeding paper, an improved component mode synthesis (CMS) technique in which experimental data as well as finite-element data are available in sub-systems has been proposed. Thi s technique, called an improved experimental free-interface method (IEFIM), has been proved to be more accurate and more efficient than the conventional experimental CMS method based on McNeal's formulation. It is due to the facts that dynamic residual terms as well as static ones are compensated from experimentally obtained FRFs and that FRFs measured on any frequencies can be used for the compensation. In this paper, the technique is applied to the component mode synthesis of a car body structure. As a result, the applicability of the technique to a large structure is demonstrated.

• Carbon letters
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• 제13권1호
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• pp.1-16
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• 2012

The near explosion of attention given to graphene has attracted many to its research field. As new studies and findings about graphene synthesis, properties, electronic quality control, and possible applications simultaneous burgeon in the scientific community, it is quite hard to grasp the breadth of graphene history. At this stage, graphene's many fascinating qualities have been amply reported and its potential for various electronic applications are increasing, pulling in ever more newcomers to the field of graphene. Thus it has become important as a community to have an equal understanding of how this material was discovered, why it is stirring up the scientific community and what sort of progress has been made and for what purposes. Since the first discovery, the hype has expediently led to near accomplishment of industrial-sized production of graphene. This review covers the progress and development of synthesis and transfer techniques with an emphasis on the most recent technique of chemical vapor deposition, and explores the potential applications of graphene that are made possible with the improved synthesis and transfer.

• The Journal of the Acoustical Society of Korea
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• 제20권4E호
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• pp.31-38
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• 2001

A large-scale synthesis database for a unit selection based synthesis method usually retains redundant synthesis unit instances, which are useless to the synthetic speech quality. In this paper, to eliminate those instances from the synthesis database, we proposed a new pruning method called weighted vector quantization (WVQ). The WVQ reflects relative importance of each synthesis unit instance when clustering the similar instances using vector quantization (VQ) technique. The proposed method was compared with two conventional pruning methods through the objective and subjective evaluations of the synthetic speech quality: one to simply limit maximum number of instance, and the other based on normal VQ-based clustering. The proposed method showed the best performance under 50% reduction rates. Over 50% of reduction rates, the synthetic speech quality is not seriously but perceptibly degraded. Using the proposed method, the synthesis database can be efficiently reduced without serious degradation of the synthetic speech quality.

• 대한화학회지
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• 제58권3호
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• pp.297-302
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• 2014

The synthetic route to coumarin systems is well established and one approach of particular interest leads to the intermediate 7-diethylamino-3-formylcoumarin. A combination of the N,N-diethylamino-coumarin donor with a wide range of acceptor groups of varying electron withdrawing strength should permit the synthesis of a series of extended coumarin dyes with absorption maxima range from 500 to 600 nm, or even beyond. In this communication, a novel efficient synthesis of indoles, benzothiazole and benzoxazole based on coumarin chromophores were achieved and the coloristic and fluorophoric properties of these chromophores were studied.

• Tribology and Lubricants
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• 제29권6호
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• pp.392-396
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• 2013

Biodiesel fuels contain unsaturated fatty acid ester, which can easily oxidize, especially when exposed to ultraviolet light. The products formed by this oxidation give rise to sediment or gum formation. As a result, the fuel can contribute to the corrosion and plugging of the filter pump. Antioxidants have been used in an effort to stabilize biodiesels, but there is still a need for a biodiesel composition with improved oxidation stability. In general, good fuel compositions should provide synergistic combinations of a biodiesel and antioxidants. Our work involved the synthesis of antioxidants to improve the oxidative stability of biodiesel fuel.

• 전자공학회논문지A
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• 제31A권2호
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• pp.116-124
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• 1994

This paper describes the design of a high-level synthesis system. ISyn: Interface Synthesis System for ISPS-A. which generates hardware satisfying timing constraints. The original version of ISPS is extended to be used for the description/capture of interface operations and timing constraints in the ISPS-A. To generate the schedule satisfying interface constraints the scheduling process is divided into two steps:pre-scheduling and post-scheduling. ISyn allocates hardware modules with I/O ports by the clique partitioning algorithm. Experimental results show that ISyn is capable of synthesizing hardware modules effectively for internal and/or interactive operations.

• 대한기계학회논문집
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• 제13권4호
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• pp.799-806
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• 1989

본 논문에서는 일반적으로 축방향 변위에 대한 모우드만을 가지고 있는 경우의 합성을 위해 축방향 변위 모우드의 커브-피팅을 이용하여 기울기 정보를 얻고 모델링된 요소의 연결부에 부여함으로써, 변위 정보만을 사용하는 방법보다 좀 더 정확한 고유값을 얻을 수 있음을 보이고자 한다.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1133-1145
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• 2000

It is necessary to develop an efficient analysis method to identify the dynamic characteristics of a large mechanical structure and update its finite element model. That is because these processes need the huge computation of a large structure and iterative estimation due to the use of the first- order sensitivity. To efficiently carry out these processes, a new method, called the generalized free-interface mode sensitivity method, has been proposed in the authors' preceeding paper. This method is based on substructuring approach such as a free-interface method and a generalized synthesis algorithm. In this paper, the proposed method is applied to the model updating of a car body structure to verify its accuracy and reliability for a large mechanical structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.536-542
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• 2000

The present paper introduces a new fixed interface component mode synthesizing technique based on the notion of higher-order field-consistency. The present technique employs higher-order residual constraint modes in addition to lower fixed interface normal modes while consistency in matching field variables at the substructure interface is maintained. The present field-consistency approach does not increase the size of the synthesized system even if higher-order residual constraint modes are included. A new field-consistent higher-order synthesis technique is first presented and a numerical example is given to verify the present method.