Cutometer 를 이용한 한국 정상 성인의 피부 탄력 성질 측정 및 Dermaflex 와의 비교

서대헌(Dae Hun Suh),이종희(Jong Hee Lee),최용범(Yong Bum Choi),권태은(Tae Eun Kwon),윤재일(Jai Il Youn) 대한피부과학회 2000 대한피부과학회지 Vol.38 No.10

Background:Many studies about the skin elastic properties have been performed until now using diverse methods. Suction methods using Dermaflex and Cutometer are most prevalently used. Objective:We performed this study to obtain the normal range of skin elastic properties using Cutometer and to know the correlation between the data of Cutometer and those of Dermaflex . Methods:Eleven different anatomical sites were measured in 46 healthy young volunteers (M:F=23:23) by Cutometer . The same anatomical sites were also measured by Dermaflex in sixteen volunteers (M:F=8:8). Results:When measured by Cutometer , skin elasticity and distensibility were generally higher in the central part of the body than the distal portion, showing the distal gradient. There were differences according to sexes and a part of them were significant. When we compared Cutometer with Dermaflex , they were closely related to each other in the data about distensibility, there was a weak correlation in the data of elasticity. No correlation was detected between Cutometer and Dermaflex in the data about hysteresis. Conclusion:This study suggests the Korean standard values of elastic properties in their twenties by Cutometer . The values measured by Cutometer and Dermaflex were not interchangeable although they were the same in the aspect of theoretical concept. These features should be considered in the future study measuring skin elastic properties. (Korean J Dermatol 2000;38(10):1333~1340)

Elastic and electronic properties of partially ordered and disordered Zr(C₁₋ <i> _x </i>N<i> _x </i>) solid solution compounds: A first principles calculation study

Kim, Jiwoong,Kwon, Hanjung,Kim, Jae-Hee,Roh, Ki-Min,Shin, Doyun,Jang, Hee Dong Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.619 No.-

<P><B>Abstract</B></P> <P>The elastic properties and electronic structures of partially ordered and disordered Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) solid solution compounds were investigated using first principles calculations to understand the effects of nitrogen content and atomic distribution. To obtain a proper exchange–correlation energy, we used local density and generalized gradient approximations with Perdew–Burke–Ernzerhof (LDA and GGA-PBE) parametrization. Partially ordered and disordered structures of Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) compounds were expressed using unit cell and special quasi-random structure (SQS) models, respectively. We demonstrated that although the disordered models have P1 symmetry with different model sizes and cell shapes compared with ordered models, they reproduce the equilibrium structure and elastic properties of the Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) compounds with B1 (Fm-3m) symmetry. However, clear differences exist in the electronic structures. Therefore, the atomic configuration is essential for calculating the electronic structures of the Zr(C<SUB>1−</SUB> <I> <SUB>x</SUB> </I>N<I> <SUB>x</SUB> </I>) compounds.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Elastic and electronic properties of Zr(C<SUB>1−<I>x</I> </SUB>N<SUB> <I>x</I> </SUB>) compounds by first principles. </LI> <LI> We elucidate the effects of atomic configuration on compound properties. </LI> <LI> Ordered and disordered models are depicted by unit cell and special quasi-random structures. </LI> <LI> Disordered structures are suitable models to estimate compound elastic properties. </LI> <LI> The atomic configuration is essential to obtain accurate electronic structures. </LI> </UL> </P>

Numerical prediction of fiber mechanical properties considering random microstructures using inverse analysis with quasi-analytical gradients

Lim, J.H.,Henry, M.,Hwang, D.S.,Sohn, D. Elsevier [etc.] 2016 Applied Mathematics and Computation Vol.273 No.-

<P>An efficient and robust numerical scheme is reported that can inversely evaluate the elastic properties of fibers in unidirectional composites from the material properties of matrices and composite laminae. Considering the effect of microstructures such as random fiber arrangement, a set of finite element meshes are employed to represent the interaction between fiber and matrix. A lamina-scale cost function comprising the difference between the measured elastic properties and the computed elastic properties of a unidirectional lamina is minimized to evaluate fiber properties. In the minimization process, quasi-analytical gradients derived from prediction formulae, such as the Chamis or Halpin-Tsai models, are adopted to greatly reduce the computation cost. To verify the proposed scheme in terms of accuracy, efficiency, and robustness, the elastic properties of T650-35 fiber in a T650-35/PMR-15 lamina are evaluated with various representative volume elements containing randomly distributed fibers and voids. The evaluation results obtained by the proposed scheme are compared with results in the literature, and the effects of microstructures are discussed. (C) 2015 Elsevier Inc. All rights reserved.</P>

Acoustic and Elastic Properties of the Southeastern Yellow Sea Mud, Korea

Kim, Gil-Young The Acoustical Society of Korea 2006 韓國音響學會誌 Vol.25 No.e2

Compressional wave velocity (Vp), shear wave velocity (Vs), elastic and physical properties, and electrical resistivity for two core sediments obtained from Southeastern Yellow Sea Mud (SEYSM) were measured and computed. The sediments consist of homogeneous mud (mostly silt and clay) with shells and shell fragments. As a result, the mean grain size is uniform ($7.5-8.5{\Phi}$ throughout the core sediments. However, physical properties such as wet bulk density and porosity show slightly increasing and decreasing patterns with depth, compared to the mean grain size. The compressional (about 1475 m/s in average) and shear wave (about 60 m/s in average) velocities with depth accurately reflect the pattern of wet bulk density and porosity. Electrical resistivity is more closely correlated with compressional wave velocity than physical properties. The computed Vp/Vs and Poisson's ratios are relatively higher (more than 10) and lower (approximately 0.002) than Hamilton's (1979) data, respectively, suggesting the typical characteristics of soft and fully water-saturated marine sediments. Thus, the Vp/Vs ratio in soft and unconsolidated sediments is not likely sufficient to examine lithology and sediment properties. Relationships between the elastic constant and physical properties are correlated well. The elastic constants (Poisson's ratio, bulk modulus, shear modulus) given in this paper can be used to characterize soft marine sediments saturated with seawater.

초탄성 고무 물성평가를 위한 구형 압입시험의 수치접근법

이진행 ( Lee Jin Haeng ),김동욱 ( Kim Dong Ug ),이형일 ( Lee Hyeong Il ) 한국고무학회 2004 엘라스토머 및 콤포지트 Vol.39 No.1

본 연구에서는 먼저 유한요소해석을 통한 주요 물성계수들이 압입시 하중-변위 곡선형상에 미치는 영향을 분석하였다. 또한 유한요소 압입해석을 통해 마찰계수의 영향으로 하중-변위 곡선, 시편하부의 단위부피당 변형에너지 및 변형률 주불변량이 바뀌지 않는 최적 압입깊이와 시편하부지점을 선정하였다. 이러한 관찰을 통해 하나의 요소에서 얻어지는 단위부피당 변형 에너지와 변형률 주불변량을 하중-변위 데이터와 모사 시킬 수 있는 무차원 함수를 얻을 수 있었으며, 이 과정에서 예측된 물성계수를 바탕으로 공칭응력-공칭변형률 곡선을 얻을 수 있었다. In this work, effects of hyper-elastic rubber material properties on the indentation load-deflection curve and subindenter deformation are first examined via finite element (FE) analyses. An optimal data acquisition spot is selected, which features maximum strain energy density and negligible frictional effect. We then contrive two normalized functions, with map an indentation load vs. deflection curve into a strain energy density vs. first invariant curve. From the strain energy density vs. first invariant curve, we can extract the rubber material properties. This new spherical indentation approach produces curve, we can extract the rubber material properties. This new spherical indentation approach produces the rubber material properties in a manner more effective than the common uniaxial tensile/compression tests. The indentation approach successfully measures the rubber material properties and the corresponding nominal stress-strain curve.

Investigations of radiation shielding using Monte Carlo method and elastic properties of PbO-SiO2-B2O3-Na2O glasses

Shams A.M. Issa,Yasser B. Saddeek,H.O. Tekin,M.I. Sayyed,Khamies saber Shaaban 한국물리학회 2018 Current Applied Physics Vol.18 No.6

Several physical parameters such as the packing density (PD), oxygen molar volume (OMV), oxygen packing density (OPD) and the elastic moduli of the quaternary glass system xPbO-(30-x)SiO2-46.67B2O3-23.33Na2O (x = 0, 5, 10 and 15 mol%) have been evaluated. The elastic moduli were computed according to Makishima-Mackenzie model and Rocherulle model. The values of these moduli have been compared to their experimental values. Moreover, different shielding parameters such as mass attenuation coefficients (MAC), half value layer (HVL), mean free path (MFP), effective atomic numbers (EAN), effective electron densities (EED) and buildup factors have been evaluated using the WinXcom program in the energy range 0.015–15 MeV for the quaternary studied glass system. The MAC values have been compared with MCNPX (version 2.6.0) Monte Carlo code. Besides, mass stopping power (MSP) for proton, alpha and electron as well as the removal cross section for fast neutron (∑R) have been calculated. The results observed that the composition has the highest value of PbO (15 mol %) showed excellent nuclear radiation shielding and elastic properties.

Nano-indentation 실험과 유한요소 해석을 연계한 재료의 탄소성 물성 평가법 개발

김윤재(Y.J Kim),송태광(T.K Song),박준협(J-H Park),한준희(J-H Hahn) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월

Determination of elastic properties of nano-scale materials using nano-indentation tests is well established, but that of plastic properties is not yet clear. This paper presents a method to extract plastic properties from nano-indentation test, together with results from detailed elastic-plastic FE analysis. It shows that the plastic properties determined from this method are not unique, in the sense that a number of different plastic properties can give the same load-displacement response from nano-indentation test. Possible ways to overcome such problems are discussed.

Ab initio investigation into the structural, electronic and elastic properties of AlCu2TM (TM = Ti, Zr and Hf) ternary compounds

Mingjun Pang,Yongzhong Zhan,Haizhou Wang 한국물리학회 2012 Current Applied Physics Vol.12 No.3

The AleCueTM (TM = transition metal) alloy system has attracted great attention for both excellent glass-forming ability and its interesting physical properties. In this work, an investigation into the crystal,electrical and elastic properties of the AlCu2TM (TM = Ti, Zr, and Hf) compounds has been conducted by first-principles calculations based on density-functional theory. The fully relaxed structure parameters of the AlCu2TM compounds are in good agreement with previous experimental and other theoretical results. Besides, the cohesive energies of all the AlCu2TM compounds have been evaluated. The energy band and densities of state of these compounds are also obtained. According to the calculated single crystal elastic constants, all the compounds are mechanically stable. The polycrystalline bulk moduli,shear moduli, Young’s moduli and Poisson’s ratio have been deduced by using VoigteReusseHill (VRH)approximations. The calculated negative Cauchy pressure and ratio of bulk modulus to shear modulus indicated that the AlCu2TM compounds are ductile materials. The Debye temperatures of the AlCu2TM compounds decrease with increasing the TM (Ti, Zr, and Hf) atomic number.

Hydrogen's influence on reduced activation ferritic/martensitic steels' elastic properties: density functional theory combined with experiment

Sinan Zhu,Chi Zhang,Zhigang Yang,Chenchong Wang 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.8

Reduced activation ferritic/martensitic (RAFM) steels are widely applied as structural materials in thenuclear industry. To investigate hydrogen's effect on RAFM steels' elastic properties and the mechanismof that effect, a procedure of first principles simulation combined with experiment was designed. Densityfunctional theory models were established to simulate RAFM steels' elastic status before and after hydrogen'sinsertion. Also, experiment was designed to measure the Young's modulus of RAFM steelsamples with and without hydrogen charging. Both simulation and experiment showed that the solubilityof hydrogen in RAFM steels would decrease the Young's modulus. The effect of hydrogen on RAFMsteels' Young's modulus was more significant in water-quenched steels than it was in tempering steels. This indicated that defects inside martensite, considered to be hydrogen traps, could decrease thecohesive energy of the matrix and lead to a decrease of the Young's modulus after hydrogen insertion.

First-principles investigation of structural, elastic, electronic and magnetic properties of Be0.75Co0.25Y (Y=S, Se and Te) compounds

W. Tanveer,M.A. Faridi,N.A. Noor,Asif Mahmood,B. Amin 한국물리학회 2015 Current Applied Physics Vol.15 No.11

We have theoretically investigated the structural, elastic, electronic and magnetic properties of Be0.75Co0.25Y (Y=S, Se and Te) alloys, in their zinc-blend phase. This study is carried out by using the fullpotential augmented plane wave plus local orbitals method within the density functional theory. Foe computing the exchange-correlation potential, the Wu and Cohen generalized gradient approximation is employed to calculate structural and elastic properties whereas the modified Becke and Johnson potential local density approximation is utilized to examine electronic and magnetic properties. By minimizing the total energy in paramagnetic (PM) and ferromagnetic (FM) phases, it is found the studied compounds are stable in FM structure. The mechanical behavior of the studied compounds is reported with the calculation of shear modulus, Young's modulus, and Poisson's ratio provides. Such mechanical aspects might be useful for the experimentalists to study the mechanical properties upon alloying BeY compounds with Co. We also compute electronic structures, density of states (total and partial), pdexchange splitting and magnetic moments. Moreover, bond nature is studied by estimating the spin polarized charge densities of Be0.75Co0.25Y (Y=S, Se and Te).