• 패션비즈니스
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• 제15권1호
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• pp.63-79
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• 2011

This study examines the relationship between breast shape and brassiere construction through the comparative analysis of brassiere pattern on the breast shape. This researcher drew the brassiere pattern of developing a pre-study for Chinese female adults according to average size based on the four breast shapes. And then we measures brassiere pattern size and comparatively analyzes breast between size and shape. Comparative analysis results of brassiere patterns are verified differences of size and shape on the breast shape. Above all an angle of cup dart showed remarkable differences on the breast shape. An angle of cup dart isn't proportioned to breast size. An angle of cup dart for cone shape is bigger than dome shape. Because cone shape breast is protruded center part but dome shape breast have a shape of smooth curve like a half globe. So an angle of a cone shape breast cup dart is determined bigger than dome shape breast. For increasing the uplift effect of brassiere, brassiere pattern is different on the breast shape. And a brassiere pattern need different drawing methods about the angle of cup dart, breast inner side diameter, slope and so on. This study has an important significance that it established a mechanical relationship of breast shape and brassiere pattern.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.141-146
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• 2012

Aluminum alloys have been used with various thicknesses suitable for light weight of structure. It is known that the thickness effect of material is an important factor affecting fatigue crack propagation under constant fatigue stress condition. In this work, we presented the behavior of fatigue crack propagation in thin plate compared to thick plate Al 2024-T3 alloy with referred thickness effect in a correlative equation determined by the shape factor and the loading factor. We chose two factors that are used in the correlative equation with considering that the experiments were carried out under a constant fatigue stress condition. The thickness ratio of thin plate compared to thick plate and the equivalent effective stress intensity factor ratio depending on thickness were chosen as shape and loading factors. A correlative equation is utilized to determine the equivalent effective stress intensity factor range of thin plate and identify the degree of increasing phenomenon of fatigue life in thin plate compared to thick plate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.186-191
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• 2001

Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 shape memory alloy(SMA) composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation and volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 SMA composite. In addition, two dimensional AE source location technique was applied to inspect the crack initiation and propagation in composite.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.72-77
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• 2001

Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi fiber was used to solve the tensile residual stress as the reinforced material. TiNi fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 shape memory alloy composite.

• 터널과지하공간
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• 제31권6호
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• pp.440-459
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• 2021

최근 대형 로드헤더가 국내 터널현장에 도입되면서 해외 제조사의 굴진율 예측모델에 대한 관심이 증가하고 있다. 현재 주로 사용되는 해외모델은 압축강도로부터 굴진율을 예측하고 있는데, 암석 시험편의 직경 대 길이의 비율이 1.0인 시편을 일축압축시험으로 사용하고 있다. 일반적으로 시편의 형상과 치수는 강도에 영향을 미치는 것으로 알려져 있다. 본 기술보고에서는 직경 대 길이 비율에 따른 암석강도의 변화에 대한 기존 연구사례를 조사하였다. 그 형상효과에 대한 원인을 이론적으로 고찰하였다. 이를 토대로 국내 예정된 암종에 대해서 길이 비율에 따른 강도의 변화 양상을 예측하고 굴진율 수정모델을 제시하였다.

• Fibers and Polymers
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• 제7권4호
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• pp.328-332
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• 2006

Poly(ethylene terephthalate) (PET) and poly(ethylene glycol) (PEG) copolymers cross-linked with pentaerythritol, a four-way cross-linker, are prepared to compare their mechanical and shape memory properties with the one cross-linked by glycerol. Composition of PEG and pentaerythritol is varied to search for the one with the best mechanical and shape memory properties. The highest shape recovery rate is observed for the copolymer composed of 30 mol% PEG-200 and 2.5 mol% pentaerythritol. Four-way cross-linking by pentaerythritol significantly improves shape recovery rate and retention of high shape recovery rate after repeated use compared to the one cross-linked by glycerol, a three-way cross-linker, and difference and advantage of additional cross-linking point are discussed.

• 한국재료학회지
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• 제8권11호
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• pp.993-998
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• 1998

본 연구는 형상기억합금을 이용하여 제조한 신소재 중의 하나인 형상기억복합재료를 소개하고자 한다. 이 복합재료는 TiNi 섬유의 형상기억효과로 금속복합재료의 취약점이라 할 수 있는 기지와 섬유간의 열팽창차이로 인한 인장잔류응력을 제거하고 기지내에 압축잔류응력을 발생시켜 높은 인장강도를 갖는다. 따라서 본 연구에서는 용탕단조법으로 복합재료를 제조한 후 미세조직을 관찰하고 TiNi 섬유의 역변태온도 이상에서 피로실험을 수행하여 복합재료의 피로특성을 검토하였다. 이 결과 363K에서의 피로균열전파제어효과는 섬유체적률과 예변형에 의하여 증가된다.

• 비파괴검사학회지
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• 제27권4호
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• pp.328-338
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• 2007

스마트 재료를 이용한 복합재료의 가장 큰 장점 중의 하나는 재료내부에 발생한 균열을 제어하는데 있다. 구조용 재료로 사용 중에 구조물 내에 균열이 발생할 때 균열의 진전을 억제할 수 있는 방법 중의 하나가 형상기억합금재료의 형상기억효과를 이용하는 것이다. 본 연구에서는 최적의 제조조건을 도출하여 형상기억합금을 이용한 형상기억복합재료를 제조하였다. 또한 형상기억복합재료 내부의 형상기억합금에 의한 형상기억효과를 평가하기 위하여 복합재료에 인장하중을 가하여 복합재료에 발생하는 응력분포를 평가하고 복합재료에 열을 가하여 형상기억합금을 원래의 상태로 복귀하면서 복합재료 전체의 응력변화를 평가하였다. 형상기억복합재료의 인장하중에 따른 응력분포를 관찰하기 위하여 광탄성에 의한 가시화 장치를 이용하였다.

• 한국농공학회지
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• 제42권5호
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• pp.151-159
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• 2000

Dynamic loading of structures often causes excursions of stresses will into the inelastic range and the influence of geometry changes on the response is also significant in may cases. In general , the shell structures designed according to quasi-Static analysis may collapse under condition of dynamic loading. Therefore, for a more realistic prediction on the lad carrying capacity of these shell. both material and geometric nonlinear effects should be considered. In this study , the material nonlinearity effect on the dynamic response is formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a Total Lagrangian formulation. the reinforcing bars are modeled by the equivalent steel layer at the location of reinforcements, and Von Mises yield criteria is adopted for the steel layer behavior. Also, Drucker-Prager yield criteria is applied for the behavior of concrete. the shape imperfection of dome is assumed as 'dimple type' which can be expressed Wd1=Wd0(1-(r-a)m)n while the shape imperfection of wall is assumed as sinusoidal curve which is Wwi =Wwo sin(n $\pi$y/l). In numerical test, three cases of shape imperfection of 0.0 -5.0cm(opposite direction to loading ; inner shape imperfection)and 5cm (direction to loading : outward shape imperfection) and thickness of steel layer determined by steel ratio of 0,3, and 5% were analyzed. The effect of shape imperfection and steel ratio and behavior characteristics of perfect shape shell and imperfect shape shell are identified through analysis of above mentioned numerical test. Dynamic behaviors of dome and wall according toe combination of shape imperfection and steel ratio are also discussed in this paper.

• 한국항공우주학회지
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• 제36권8호
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• pp.790-796
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• 2008

고체 추진기관은 고정된 추진제 그레인 형상과 노즐목 때문에 정해진 단순 추력을 가지게 된다. 핀틀 노즐은 기존의 고체 추진기관의 장점을 가지면서도 추력 조절이 불가능한 단점을 보완하기 위해 제안된 방법이다. 본 연구에서는 핀틀 형상이 노즐 성능에 미치는 영향을 실험과 수치해석 방법으로 평가하였다. 핀틀 형상은 단순성의 원리에 근거하여 변경하였으며 각각의 형상에 대한 내부 유동장은 난류모델을 적용하여 Fluent로 해석하였다. 본 연구로부터 핀틀 형상이 노즐내의 충격파 구조 및 유동박리 영향을 주어 노즐 추력 및 핀틀 하중에 영향을 미침과 최적의 노즐 성능을 발휘할 수 있는 핀틀 형상이 존재함을 확인하였다.