• 한국식품과학회지
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• 제35권1호
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• pp.155-158
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• 2003

겨자 페이스트의 시간의존성을 관찰하기 위해 총고형분 함량(18, 21, 24, 27, 30%)과 전단속도$(15,\;20,\;25\;s^{-1})$를 달리하여 시간-전단응력 변화가 분석되었으며, 이들 데이터들은 Figoni 및 Shoemaker 모델, Weltman 모델, Hahn 모델에 적용하여 정량적으로 평가되었다. 일정한 전단속도에서 겨자페이스트의 농도가 증가함에 따라 보다 높은 전단응력을 나타냈으며, 3종류의 모델식에서의 각 매개변수들은 농도에 따라 일정한 경향을 나타내어 겨자 페이스트의 시간의존 유동 특성에는 다른 분산식품들과 마찬가지로 농도에 의해 크게 영향을 받음을 알 수 있었다. 그러나 일정 농도를 기준으로 전단속도에 따른 시간의존성 변화에서는 25%와 27%농도를 가진 시료를 제외하고는 각 매개변수 값들의 차이는 거의 없는 것으로 나타났다. 시간의존 유동특성 모델에 적용한 결과, Weltman 모델이 다른 모델식에 비해 가장 높은 결정계수$(R^2)$을 보여주고 있어 Weltman 모델식이 겨자 페이스트 시간의존성을 나타내는 가장 적합한 모델식임을 알 수 있었다.

• 한국세라믹학회지
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• 제24권3호
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• pp.289-295
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• 1987

The changes of physical properties of portland cement pastes and mortars were investigated by addition of sodium gluconate. Flow table experiment and viscosity measurement were took in order to find dispersing effect, and time-dependent changesof viscosity and rates of hydration heat evolution were carried out for the sake of finding retardation effect of hydration. And changes of physical properties of cement pastes and mortars were discussed by setting time, compressive strength and porosity.

• 정보저장시스템학회논문집
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• 제1권2호
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• pp.132-136
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• 2005

It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.

• Structural Engineering and Mechanics
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• 제46권1호
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• pp.53-73
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• 2013

Prediction of prestressed concrete girder integral abutment bridge (IAB) load effect requires understanding of the inherent uncertainties as it relates to thermal loading, time-dependent effects, bridge material properties and soil properties. In addition, complex inelastic and hysteretic behavior must be considered over an extended, 75-year bridge life. The present study establishes IAB displacement and internal force statistics based on available material property and soil property statistical models and Monte Carlo simulations. Numerical models within the simulation were developed to evaluate the 75-year bridge displacements and internal forces based on 2D numerical models that were calibrated against four field monitored IABs. The considered input uncertainties include both resistance and load variables. Material variables are: (1) concrete elastic modulus; (2) backfill stiffness; and (3) lateral pile soil stiffness. Thermal, time dependent, and soil loading variables are: (1) superstructure temperature fluctuation; (2) superstructure concrete thermal expansion coefficient; (3) superstructure temperature gradient; (4) concrete creep and shrinkage; (5) bridge construction timeline; and (6) backfill pressure on backwall and abutment. IAB displacement and internal force statistics were established for: (1) bridge axial force; (2) bridge bending moment; (3) pile lateral force; (4) pile moment; (5) pile head/abutment displacement; (6) compressive stress at the top fiber at the mid-span of the exterior span; and (7) tensile stress at the bottom fiber at the mid-span of the exterior span. These established IAB displacement and internal force statistics provide a basis for future reliability-based design criteria development.

• Steel and Composite Structures
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• 제12권5호
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• pp.413-426
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• 2012

In this paper, nonlinear static analysis of three-dimensional cable stayed bridges is performed for the time dependent materials properties such as creep, shrinkage and aging of concrete and relaxation of cable. Manavgat Cable-Stayed Bridge is selected as an application. The bridge located in Antalya, Turkey, was constructed with balanced cantilever construction method. Total length of the bridge is 202 m. The bridge consists of one $\ddot{e}$ shape steel tower. The tower is at the middle of the bridge span. The construction stages and 3D finite element model of bridge are modeled with SAP2000. Large displacement occurs in these types of bridges so geometric nonlinearity is taken into consideration in the analysis by using P-Delta plus large displacement criterion. The time dependent material strength and geometric variations are included in the analysis. Two different finite element analyses carried out which are evaluated with and without construction stages and results are compared with each other. As a result of these analyses, variation of internal forces such as bending moment, axial forces and shear forces for bridge tower and displacement and bending moment for bridge deck are given with detailed. It is seen that construction stage analysis has a remarkable effect on the structural behavior of the bridge.

• Steel and Composite Structures
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• 제30권6호
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• pp.567-576
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• 2019

Time-dependent creep analysis of a rotating functionally graded cantilever beam with trapezoidal longitudinal cross section subjected to thermal and inertia loading is investigated using first-order shear deformation theory (FSDT). The model described in this paper is a simple simulation of a turbine blade working under creep condition. The material is a metal based composite reinforced by a ceramic where the creep properties of which has been described by the Sherby's constitutive model. All mechanical and thermal properties except Poisson's ratio are assumed to be variable longitudinally based on the volume fraction of constituent. The principle of virtual work as well as first order shear deformation theory is used to derive governing equations. Longitudinal distribution of displacements and stresses are investigated for various volume fractions of reinforcement. Method of successive elastic solution is employed to obtain history of stresses and creep deformations. It is found that stresses and displacements approach their steady state values after 40000 hours. The results presented in this paper can be used for selection of appropriate longitudinal distribution of reinforcement to achieve the desired stresses and displacements.

• 천문학회지
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• 제27권2호
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• pp.177-190
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• 1994

We have examined the photometric evolution of elliptical galaxies, using stellar evolutionary models covering the wide ranges of metallicity and mass, and the different IMFs (simple IMP & time-dependent bimodal IMF). The model with a time-dependent bimodal IMF can reproduce the observed integrated magnitudes and colors at all wavelengths. The computed model shows that the star formation in elliptical galaxies is still going on, although the number of newly born stars is very small. The chemical evolutionary effect is clearly seen in the C-M diagram of computed elliptical galaxies.

• 통합자연과학논문집
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• 제4권1호
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• pp.1-6
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• 2011

The properties of porous silicon, such as substrate properties, porosity, thickness, refractive index, surface area, and optical properties of porous silicon were reviewed. Some properties, such as porosity, refractive index, thickness, pore diameter, multi-structures, and optical properties, are strongly dependent on the anodization process parameters. These parameters include HF concentration, current density, anodization time, and silicon wafer type and resistivity.

• 한국대기환경학회지
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• 제19권2호
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• pp.191-204
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• 2003

A one dimensional time dependent acid rain model considering size distribution of aerosols and hydrometeors is developed to predict observed chemical and physical properties of precipitation. Temporal variations of anions and cations observed are predicted fairly well with acid rain model simulations. It is found that aerosol depletion rates are highly dependent on aerosol sizes under the assumption of Marshall - Palmer raindrop size distribution. Also, the aerosol depletion during the initial rain event largely influences on ion concentrations in rainwaters.

• Bulletin of the Korean Chemical Society
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• 제17권1호
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• pp.61-65
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• 1996

The semiempirical time-dependent Hartree-Fock PM3 calculations have been performed on three polyene systems. In order to study the nonlinear optical properties, we calculated the frequency-dependent first-, second-, and third-order polarizabilities of thiophene-, furan-, pyrrole-nitro polyene systems. The PM3 predicted average and longitudinal polarizabilties increase in the order: thiophene- > pyrrole- > furan-nitro polyene systems. The PM3 predicted limiting average second-order polarizabilities show the order: pyrrole- > furan- > thiophene-nitro polyene systems. The average and longitudinal third-order polarizabilties have the following order: pyrrole- > thiophene- > furan-nitro polyene systems. In these trends, we sugest that pyrrole group is the best donor group among the three polyene systems.