• 대한기계학회논문집A
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• 제28권6호
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• pp.726-731
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• 2004

This paper suggests a material mixing method to mix several materials in a structure. This method is based on ESO(Evolutionary Structural Optimization), which has been used to optimize topology of only one material structure. In this study, two criterions for material transformation and element removal are implemented for mixing several materials in a structure. Optimal topology for a multiple material structure can be obtained through repetitive application of the two criterions at each iteration. Two practical design examples of a short cantilever are presented to illustrate validity of the suggested material mixing method. It is found that the suggested method works very well and a multiple material structure has more stiffness than one material structure has under the same mass.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.259-264
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• 2003

This paper suggests a material mixing method to mix several materials in a structure. This method is based on ESO(Evolutionary Structural Optimization), which has been used to optimize topology of only one material structure. In this study, two criterions for material transformation and element removal are implemented for mixing several materials in a structure. Optimal topology for a multiple material structure can be obtained through repetitive application of the two criterions at each iteration. Two practical design examples of a short cantilever are presented to illustrate validity of the suggested material mixing method. It is found that the suggested method works very well and a multiple material structure has more stiffness than one material structure has under the same mass.

• Structural Engineering and Mechanics
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• 제33권3호
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• pp.285-306
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• 2009

In the literature the problem of the topology optimization of the structure is usually solved for one, clearly described from the mechanical point of view material. Generally the topology optimization answers the question of the distribution of this mentioned above material within the design domain. Finally, material-voids distribution it is obtained. In this paper, for the structure mainly strengthened or sometimes weakened by the inclusions, the variation approach of the topology optimization problem is formulated. This multi material approach may be useful for the design process of various mechanical or civil engineering structures which need to be more "refined" and more "optimal" than they can be using previous topology optimization procedures of optimization one material structures.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 춘계학술대회 논문집
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• pp.108-113
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• 1993

The material for the machine tool structure should have high static stiffiness and damping in its property to improve both the static and dynamic performances. The static stiffness of a machine tool can be inceased by using either higher modulus material in the structure of a machine tool. However, the machine tool structrue with high stiffness but low damping is vulnerable to vibration at the resonance frequencies of the structure . For the high precision and highsped machine tool structure, therefore, the high damping capacity is most important in order to suppress vibration. The damping of a machine tool can not be increased by increasing the static stiffness. The best way to increase the damping capacity of the machine tool structure is to use a composite material which is composed of on material with high stiffness with low damping and another material with low stiffness with high damping. Therefore, in this paper, the bed of the ultra high precision grinding machine for mirror surface machining of brittle materials such as ceramics and composite materials was designed and manufactured with the epoxy concrete material. The epoxy concrete material was prepared by mixing epoxy resin with different size sands and gravels. The modulus, compressive strength, coefficient of thermal expansion, specific heat, and damping factor were measured by varying the compaction ratio, sizes and contents of the ingredients to assess the effect of the processing parameters on the mechanical properties of the material. Based of the measured properties, the prototype epoxy resin concrete bed for the mirror surface CNC grinding machine was designed and manufactured.

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6504-6513
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• 2013

본 연구에서 농촌주택을 대상으로 농촌주택의 구법과 재료의 지역별 시기별 변화 특징 분석결과, 지붕형태는 팔작지붕/우진각지붕(1970)-평지붕(1980)-맞배지붕(1990), 지붕구조재료는 한식목조/간이한식목조-파라펫눈썹지붕/경사슬래브-양식목조-경량철골조, 지붕마감재료는 초가/한식기와-슬레이트-시멘트/강판-아스팔트슁글/샌드위치패널/몰탈방수, 벽체구조재는 한식목조/간이한식목조-시멘트조적조-RC조-경량철골조/양식목조, 벽체마감재료는 흘미장/회벽-치장벽돌쌓기/시멘트미장위 페인트마감-자연석치장/사이딩/타일, 담장재료는 전시기별로 돌담과 시멘트블록, 마당재료는 흙바닥, 콘크리트가 사용된 것으로 나타났다. 지역별 변화특징으로 주택구조, 지붕형태, 지붕구조재료, 벽체마감재료, 외부공간에서 담장재료와 마당재료는 북부지역, 중부지역, 남부지역별로 농촌주택 특징변화의 차이가 나타났으며, 지붕구조재료, 벽체구조재료는 지역별로 유사한 변화양상이 나타나는 것으로 분석되었다.

• 건축역사연구
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• 제20권2호
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• pp.55-70
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• 2011

This paper aimed at analyzing of structural carpentry terminology for bracket structure in Yingzaofashi ${\ll}$營造法式${\gg}$in the era of Song Dynasty and illuminating coinage characteristics and method of Structural Carpentry Terminology for bracket Structure through graphonomy research and system and structure of these terms. The results are as follow. The structural carpentry terminologies for structure were identified to be approximately 23 words, and terminology of bracket structure鋪作 is largely categorized into 3 categories of Type鋪作次序, Structure, Place. On the other hand, the structural carpentry terminologies for parts largely categorized into 2 categories of Bracket structure鋪作, Others. Bracket structure terminologies for parts were derived from the core of Dou枓, Gong栱, Ang昂, Fang方. The phenomena of derivation in structural carpentry terminology for bracket structure can be explained by the difference in the shape of subsidiary material and the location for usage of the subsidiary material and part of the subsidiary material and their functions.

• 한국공간구조학회논문집
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• 제16권2호
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• pp.55-60
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• 2016

The Membrane structure has a number of problems in the application of a fireproof code based on general buildings codes. Thus, the fireproof code of membrane structure is necessary to activate the construction of the membrane structure. Because it requires a systematic classification of fire retardant and flame proof performance of membrane material. Fire retardant and flame proof tests are conducted on membrane materials mostly used in current construction to propose the fire and flame retardant performance criteria of membrane materials. Fire and flame retardant tests results, PTFE membrane material with the glass fiber fabric have a limit-combustible performance. PVDF membrane material with the polyester fabric does not ensure the fire retardant performance, but this membrane material has the flame retardant performance of a thick fabric. Also, ETFE does not ensure the fire retardant performance, but this membrane material has the flame retardant of a thin fabric.

• 한국안전학회지
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• 제21권3호
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• pp.87-93
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• 2006

When a structure is constructed at the site composed of soil, the behavior of a structure is much affected by the characteristics of soil. Therefore, the effect of soil-structure interaction is an important consideration in the design of a structure at the site composed of soil. Precise analysis of soil-structure interaction requires a proper description of soil profile. However, most of approaches are nearly unpractical for soil exhibiting material discontinuity and complex geometry since those cannot consider precisely complicated soil profiles. To overcome these difficulties, an improved integration method is adopted and enables to integrate easily over an element with material discontinuity. As a result the mesh can be generated rapidly and highly structured, leading to regular and precise stiffness matrix. The influence of soil profile on the response is examined by the presented method. It is seen that the presented method can be easily used on soil-structure interaction problems with complicated soil profile and produce reliable results regardless of material discontinuities.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.821-824
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• 2008

This paper presents a systematic approach for estimating material performance of concrete mixture design based on satisfaction curves developed from statistical evaluation of existing or newly obtained material property related data. In performance based material design (PBMD) method, concrete material used for construction of a structure is designed considering a structure's specified performance requirements based on its usage and characteristics such as environmental conditions, structure types, expected design life, etc.Satisfaction curves express the probabilities that one component of substrates (i.e., aggregate size, cement content, etc) of concrete mixture will sustain different criterion value for a given concrete mixture design. This study presents a statistical analysis method for setting up concrete material parameter versus concrete criterion relationships in the form of satisfaction curves and for estimating confidence bounds on these satisfaction curves. This paper also presents an analysis method to combine multiple satisfaction curves to form one unique satisfaction curve that can relate the performance of concrete to a single evaluating value. Based on several evaluated mixture design examples for various material properties, the validity of the proposed method is discussed in detail.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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• pp.51-59
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• 2012

Piezoelectric langasite crystals have superior properties such as high temperature performance and high quality Q and can be applied in combustion pressure sensors and surface acoustic wave (SAW) filters. Crystal growth, crystal structure and properties of langasite group are reviewed, and the mechanism of piezoelectricity of langasite is presented based on the crystal structure and deformation under high pressure. Finally, for the discovery of new piezoelectric materials, this paper presents the role of the framework, and recommends the search of framework crystal structure, because the characteristic of the mechanism exists on the framework of the crystal structure.