• Structural Engineering and Mechanics
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• 제54권4호
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• pp.755-769
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• 2015

In this study, a 2-D finite element formulation in the frame of nonlocal integral elasticity is presented. Subsequently, the bending problem of a nanobeam under different types of loadings and boundary conditions is solved based on classical beam theory and also 3-D elasticity theory using nonlocal finite elements (NL-FEM). The obtained results are compared with the analytical and numerical results of nonlocal differential elasticity. It is concluded that the classical beam theory and the nonlocal differential elasticity can separately lead to significant errors for the problem under consideration as distinct from 3-D elasticity and nonlocal integral elasticity respectively.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.973-974
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• 2009

• 한국콘텐츠학회논문지
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• 제21권3호
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• pp.184-193
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• 2021

본 연구는 우리나라 16개 지역을 대상으로 기술혁신활동과 그 경제적 성과를 분석하였다. 실증분석은 과학기술정책연구원의 서베이 data를 이용하였고, 분석모형은 R&D지출과 매출액에 대한 단순모형 I과 노동변수를 추가한 Cobb-Douglas 모형 II로 분석하였다. 분석결과 모형 I은 전국을 대상으로 한 분석에서는 R&D 지출에 대한 매출액 탄력성이 0.42로 추정되었으며, 지역별로 보면 울산이 0.66으로 최고치를 보인 반면 부산지역은 0.2로 최저치를 보여주고 있다. 모형 II에서는 R&D 지출의 통계적 유의성이 약하고 상대적으로 노동의 통계적 유의성은 높게 나타나고 있는데, 이는 기술투자가 경제적 성과로 나타나는 데에 불확실성이 보다 강하게 존재하기 때문으로 보인다. 이를 보완하기 위해 분산분석을 통해 동질적인 지역을 대상으로 3개 권역으로 구분하였는데, Group A는 상대적으로 규모가 작고 높은 R&D집약도를 보이고 있으며, Group C는 규모가 큰반면 낮은 R&D집약도를 보이고 있다. 분석 결과는 모형 I에서 매출액에 대한 R&D 탄력성은 Group C가 0.48로서 가장 높게 나타나고 있고, Group B는 0.38, Group A는 0.29로서 권역별 차이가 뚜렷하게 나타났다. 모형 II에서는 매출액에 대한 R&D 탄력성은 Group C가 0.088로서 가장 높고, Group B는 0.086, Group A는 0.031의 순으로 나타났다. 노동 탄력성은 Group A가 1.16으로 가장 높고, Group C가 1.13, Group B는 1.10순으로 나타나고 있는데, 이는 중소기업이 다수인 지역에서 매출액에 대한 R&D 탄력성보다는 노동탄력성이 크게 나타나고 있음을 보여주고 있다.

• KSBB Journal
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• 제31권3호
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• pp.178-185
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• 2016

Aging of the face is mainly related to the features that are sagging or loss of elasticity of the skin by reducing the volume around the eyes or cheek. Intrinsic aging can be seen to cause thinner dermis, reduction of extracellular matrix and subcutaneous fat. This study was carried out to investigate the skin volume augmentation and anti-wrinkle effects of Tribulus terrestris fruit extract. Skin anti-aging effect of Tribulus terrestris fruit extract was evaluated by using lipid accumulation, expressin of type I procollagen and elastin in preadipocytes and human dermal fibroblasts. Tribulus terrestris fruit extract augmented preadipocytes differentiation about 56% at 100 µg/mL. The type I procollagen and elastin were increased about 35% and 25% by treatment 20% Tribulus terrestris fruit extract, respectively. The clinical study also showed that skin sagging, skin elasticity, and dermal density improved without adverse effect following 4 week application of cream containing 2% Tribulus terrestris fruit extract. We suggest that Tribulus terrestris fruit extract can have the good possibility as skin volume augmenting, skin elasticity and wrinkle improving agent.

• Advances in nano research
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• 제9권4호
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• pp.295-307
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• 2020

The vibrational characteristics of Multi-Phase Nanocomposite (MPC) reinforced annular/circular plate under initially stresses are presented using the state-space formulation based on three-dimensional elasticity theory (3D-elasticity theory) and Differential Quadrature Method (DQM). The MPC reinforced annular/circular plate is under initial lateral stress and composed of multilayers with Carbon Nanotubes (CNTs) uniformly dispersed in each layer, but its properties change layer-by-layer along the thickness direction. The State-Space based Differential Quadrature Method (SS-DQM) is presented to examine the frequency behavior of the current structure. Halpin-Tsai equations and fiber micromechanics are used in the hierarchy to predict the bulk material properties of the multi-scale composite. A singular point is investigated for modeling the circular plate. The CNTs are supposed to be randomly oriented and uniformly distributed through the matrix of epoxy resin. Afterward, a parametric study is done to present the effects of various types of sandwich circular/annular plates on frequency characteristics of the MPC reinforced annular/circular plate using 3D-elasticity theory.

• 기술혁신연구
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• 제19권3호
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• pp.57-83
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• 2011

본 연구에서는 CGE(Computable General Equilibrium)모형을 이용하여 28개 산업별 R&D투자액의 GDP 파급효과를 추정한 뒤, 그 결과로써 GDP의 R&D투자탄력성을 계산하여 산업별 R&D 투자 우선순위를 제시하였다. 우선순위는 28개 대분류 산업 중 전체 연구 개발투자에서 차지하는 비중이 1% 미만인 16개 산업을 제외한 12개 산업에 대해서만 적용해 보았다. 먼저 GDP의 R&D투자 탄력성에 근거한 우선순위는 제1차 금속제품, 화학제품, 음식료품, 전기 및 전자기기, 수송장비, 금속제품, 정밀기기, 전력 가스 및 수도, 일반기계, 통신 및 방송, 건설, 사회 및 기타 서비스, 부동산 및 사업 서비스 순이었다. GDP의 R&D투자탄력성에 근거한 순위설정은 비교적 우리나라 산업들의 현황을 잘 보여주고 있는 것으로 판단된다. 보조 지표인 2030년 기준 균형 대비 GDP 증가율에 근거한 우선순위 역시 판정기준으로 유사한 결과를 보여주었다. 결국 두 개의 우선순위 기준은 국가과학기술위원회의 R&D예산투자방향 및 기준 설정과 주요 사업별 예산배분 방향에 좋은 판정기준으로 활용될 수 있음을 보여주었다.

• 대한화장품학회지
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• 제30권3호
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• pp.385-388
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• 2004

최근에 천연성분의 화장품 응용에 대한 관심이 높아지고 식물에 함유하고 있는 피토에스트로겐(Phytoestrogen)의 항노화 물질 연구가 중요해지고 있다. 태국 식물 Pueraria mirifica 추출물을 $4\%$ 함유한 크림제제(PM 크림)를 추출물 성분이 제외된 플라시보 크림과 비교하여 총 30명 여성을 대상으로 16주간 임상시험을 수행하였다. 피부 모사판을 제작하여 주름 측정을 하였고, 피부 탄력과 보습을 기기 평가하였다. 특히 피부 탄력도는 placebo 크림 사용군 대비 추출물 함유 크림 사용군이 통계적으로 유의하게 탄력도가 증가하였다. 주름이나 보습평가는 특이할 만한 결과를 나타내지는 못했다. Pueraria mirifiaca는 피부 탄력 개선을 주는 항노화 화장품 개발에 응용될 수 있을 것이라 기대된다.

• 한국농공학회지
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• 제35권4호
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• pp.38-46
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• 1993

This study is to analyze effect of exposure environment and mode of ASR on the engineering properties of synthetic lightweight aggregate concrete, such as dynamic modulus of elasticity and ultrasonic pulse velocity. The results of this study are summarized as foflows ; 1. The expansion rate of each exposure environment in 380$^{\circ}$C and NaCI 4% solution was shown higher than in 20$^{\circ}$C and normal water. The expansion rate of each exposure mode was largely shown in order of fjill immersion, wetting/drying, half immersion. 2. The dynamic modulus of elasticty and ultrasonic pulse velocity of each exposure environment in 38$^{\circ}$C and NaCl 4% solution was shown less than in 20$^{\circ}$C and normal water. The dynamic modulus of elasticity and ultrasonic pulse velocity of each exposure mode was shown smaller in order of full immersion, wetting/drying, half imersion.3. The relation between dynamic modulus of elasticity and ultrasonic pulse velocity was highly significant. The dynamic modulus of elasticity was increased with increase of ultrasonic pulse velocity. The decreasing rate of the dynamic modulus of elasticity was shown 2.1~3.4 times higher than the ultrasonic pulse velocity at each age, exposure environment and mode, respectively. 4. The expansion of each exposure environment and mode was increased with increase of curing age. The dynamic modulus of elasticity and ultrasonic pulse velocity of those concrete was increased with increase of curing age. At the curing age 28 days, the highest properties was showed at each type concrete, it was gradually decreased with increase of curing age. Specially, at the curing age 98 days of full immersion, the rate of expansion of type D was shown 3.95 times higher than the type A. But the dynamic modulus of elasticity and ultrasonic pulse velocity was decreased 17% and 8.3%.

• Steel and Composite Structures
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• 제27권2호
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• pp.201-216
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• 2018

In this paper, three-dimensional (3D) elasticity theory in conjunction with nonlocal strain gradient theory (NSGT) is developed for mechanical analysis of anisotropic nanoparticles. The present model incorporates two scale coefficients to examine the mechanical characteristics much accurately. All the elastic constants are considered and assumed to be the functions of (r, ${\theta}$, ${\varphi}$), so all kind of anisotropic structures can be modeled. Moreover, all types of functionally graded spherical structures can be investigated. To justify our model, our results for the radial vibration of spherical nanoparticles are compared with experimental results available in the literature and great agreement is achieved. Next, several examples of the radial vibration and wave propagation in spherical nanoparticles including nonlocal strain gradient parameters are presented for more than 10 different anisotropic nanoparticles. From the best knowledge of authors, it is the first time that 3D elasticity theory and NSGT are used together with no approximation to derive the governing equations in the spherical coordinate. Moreover, up to now, the NSGT has not been used for spherical anisotropic nanoparticles. It is also the first time that all the 36 elastic constants as functions of (r, ${\theta}$, ${\varphi}$) are considered for anisotropic and functionally graded nanostructures including size effects. According to the lack of any common approximations in the displacement field or in elastic constant, present theory can be assumed as a benchmark for future works.

• Structural Engineering and Mechanics
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• 제51권6호
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• pp.1067-1089
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• 2014

In this paper, three dimensional static and dynamic analyses of two dimensional functionally graded annular sector plates have been investigated. The material properties vary through both the radial and axial directions continuously. Graded finite element and Newmark direct integration methods have been used to solve the 3D-elasticity equations in time and space domains. The effects of power law exponents and different boundary conditions on the behavior of FGM annular sector plate have been investigated. Results show that using 2D-FGMs and graded elements have superiority over the homogenous elements and 1D-FGMs. The model has been compared with the result of a 1D-FGM annular sector plate and it shows good agreement.