• 산업식품공학
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• 제21권4호
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• pp.303-311
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• 2017

To automate cooking processes, quantitative descriptions are needed on how quality parameters, such as texture change during heating. Understanding mechanical property changes in foods during thermal treatment due to changes in chemical composition or physical structure is important in the context of engineering models and in precise control of quality in general. Texture degradation of food materials has been studied widely and softening kinetic parameters have been reported in many studies. For a better understanding of kinetic parameters, applied kinetic models were investigated, then rate constants at $100^{\circ}C$ and activation energy from previous kinetic studies were compared. The food materials are hardly classified into similar softening kinetics. The range of parameters is wide regardless of food types due to the complexity of food material, different testing methods, sample size, and geometry. Kinetic parameters are essential for optimal process design. For broad and reliable applications, kinetic parameters should be generated by a more consistent manner so that those of foods could be compared or grouped.

• Structural Engineering and Mechanics
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• 제69권5호
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• pp.547-555
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• 2019

In this study, vibration analysis of a concrete foundation-reinforced by $SiO_2$ nanoparticles resting on soil bed is investigated. The soil medium is simulated with spring constants. Furthermore, the Mori-Tanaka low is used for obtaining the material properties of nano-composite structure and considering agglomeration effects. Using third order shear deformation theory or Reddy theory, the total potential energy of system is calculated and by means of the Hamilton's principle, the coupled motion equations are obtained. Also, based an analytical method, the frequency of system is calculated. The effects of volume percent and agglomeration of $SiO_2$ nanoparticles, soil medium and geometrical parameters of structure are shown on the frequency of system. Results show that with increasing the volume percent of $SiO_2$ nanoparticles, the frequency of structure is increased.

• Steel and Composite Structures
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• 제38권4호
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• pp.447-462
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• 2021

In this work, we consider a problem in the context of thermoelectric materials with memory-dependent derivative for a half space which is assumed to have variable thermal conductivity depending on the temperature. The Lamé's modulii of the half space material is taken as a function of the vertical distance from the surface of the medium. The surface is traction free and subjected to a time dependent thermal shock. The problem was solved by using the Laplace transform method together with the perturbation technique. The obtained results are discussed and compared with the solution when Lamé's modulii are constants. Numerical results are computed and represented graphically for the temperature, displacement and stress distributions. Affectability investigation is performed to explore the thermal impacts of a kernel function and a time-delay parameter that are characteristic of memory dependent derivative heat transfer in the behavior of tissue temperature. The correlations are made with the results obtained in the case of the absence of memory-dependent derivative parameters.

• Advances in nano research
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• 제12권4호
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• pp.405-414
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• 2022

In this study, the elastic plane problem of a layered composite containing an internal or edge crack perpendicular to its boundaries in its lower layer is examined using numerical analysis. The layered composite consists of two elastic layers having different elastic constants and heights. Two bonded layers rest on a homogeneous elastic half plane and are pressed by a rigid cylindrical stamp. In this context, the Finite Element Method (FEM) based software called ANSYS is used for numerical solutions. The problem is solved under the assumptions that the contacts are frictionless, and the effect of gravity force is neglected. A comparison is made with analytical results in the literature to verify the model created and the results obtained. It was found that the results obtained from analytical formulation were in perfect agreements with the FEM study. The numerical results for the stress-intensity factor (SIF) are obtained for various dimensionless quantities related to the geometric and material parameters. Consequently, the effects of these parameters on the stress-intensity factor are discussed. If the FEM analysis is used correctly, it can be an efficient alternative method to the analytical solutions that need time.

• 셀메드
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• 제12권1호
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• pp.4.1-4.13
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• 2022

The present communication attempts to evaluate the physicochemical and preliminary phytochemical studies on the fruit of Terminalia chebula Retz. Combretaceae family. Haritaki is one of the most celebrated herbs in the Indian traditional medicine system, Ayurveda. Terminalia chebula is known to exhibit different properties like anticancer, anti-inflammatory, anti-protozoal, antimicrobial, antioxidant, hepato and renal protective activities, and in the management of metabolic syndrome. As there is no detailed standardisation work reported on fruit, the physicochemical parameters, preliminary phytochemical constants, heavy metals, analysis are carried out. The phytochemical screening indicated the presence Tannin, Alkaloid, Phenol, Carbohydrate, Steroids, Protein and Resin compounds in CO₂ extract of Haritaki. The present investigation will helpful in assessing the quality and purity of a crude drug. Thus, the study provides facts that CO₂ extract of Haritaki contains medicinally important bioactive phytochemical compounds which justifies the use of plant species as conventional medicine for treatment of many diseases.

• Steel and Composite Structures
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• 제46권6호
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• pp.759-772
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• 2023

This manuscript presents a comprehensive mathematical model to investigate buckling stability and postbuckling response of bio-inspired composite beams with helicoidal orientations. The higher order shear deformation theory as well as the Timoshenko beam theories are exploited to include the shear influence. The equilibrium nonlinear integro-differential equations of helicoidal composite beams are derived in detail using the energy conservation principle. Differential integral quadrature method (DIQM) is employed to discretize the nonlinear system of differential equations and solve them via the Newton iterative method then obtain the response of helicoidal composite beam. Numerical calculations are carried out to check the validity of the present solution methodology and to quantify the effects of helicoidal rotation angle, elastic foundation constants, beam theories, geometric and material properties on buckling, postbuckling of bio-inspired helicoidal composite beams. The developed model can be employed in design and analysis of curved helicoidal composite beam used in aerospace and naval structures.

• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.96-100
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• 1996

This paper describes a concrete method for computing characteristic impedances and effective dielectric constants of the microstrip coupled lines without and with a dielectric overlay. The frequency-independent spectral domain method is used for the analysis of these lines. This method is a powerful, accurate, and numerically efficient approach for planar transmission line structure. For designing the optimal directional coupler, the velocities of even and odd mode must be equal but velocities of these two modes are different in the conventional coupled line which is inhomogeneous. The results show that these two velocities can be almost same according to variations of structural and material parameters in terms of the overlay(superstrate).

• 터널과지하공간
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• 제26권5호
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• pp.363-374
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• 2016

여러 가지 이유로 단일시험편에서 평면이방성 암석의 5개의 독립적 탄성상수를 결정해야 할 경우, Saint-Venant 근사식은 오랫동안 매우 유용하게 사용되어 왔다. 본 논문은 이 경험적 수식이 겉보기 탄성계수로 표현되는 수식으로 전환될 수 있음을 탄성이론에 근거한 수학적 전개를 통하여 밝히고 있다. 이렇게 전환된 수식은 이방성 각도에 단조증가하는 특성을 갖고 있으며, 이방성 암반의 초기응력측정에 유용하게 사용될 것이다. 문헌의 자료를 분석한 결과, $G^2$의 측정값은 각도와 관계없이 일정한 크기이며, Saint-Venant 근사식에 의하여 유도된 값보다 작은 것으로 분석되었다. 이러한 감분은 층상의 경계면에서 미끄러짐에 의하여 발생하는 것으로 판단되며, 미끄러짐에 의한 감소비율은 층상의 결합상태와 암석의 강도에 따라 유추될 수 있다. 이러한 분석들이 향후에 계속되어 자료가 누적된다면 감소비율을 규정할 수 있고, Saint-Venant 근사식의 수정을 통하여 단일시험편으로부터 탄성상수를 결정할 수 있을 것이다.

• 한국광학회지
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• 제13권3호
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• pp.215-222
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• 2002

광기록매체용 Ge-Sb-Te다층박막 성장과정을 in-situ 타원계를 사용하여 실시간으로 모니터하여 각 층의 두께를 제어하고 성장된 Ge-Sb-Te 다층박막을 ex-site 분광타원법으로 확인하였다. 보호층인 ZnS-SiO$_2$와 기록층인 Ge$_2$Sb$_2$Te$_{5}$을 단결정실리콘 기층 위에 스퍼터링 방법으로 각각 성장시키면서 구한 타원상수 성장곡선을 분석하여 성장에 따르는 보호층의 균일성 및 기록 층의 밀도변화를 파악하고 이를 기초로 하여 Ge-Sb-Te광기록 다층박막의 두께를 정밀하게 제어하였다. Ge$_2$Sb$_2$Te$_{5}$ 단층박막 시료의 복소굴절율은 eX-Situ 분광타원분석을 통하여 구하였다. 제작된 다층구조는 설정된 다층구조인 ZnS-SiO$_2$(1400$\AA$)$\mid$ GST(200 $\AA$)$\mid$ZnS-SiO$_2$(200$\AA$)와 각 층의 두께 및 전체 두께에서 1.5% 이내에서 일치하는 정확도를 보여주었다.주었다.

• 비파괴검사학회지
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• 제19권3호
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• pp.180-188
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• 1999

SiC 입자강화 2124Al 금속복합재료의 강화재 부피분율에 따른 탄성 stiffness를 초음파 공명 스펙트로스코피(resonant ultrasound spectroscopy: RUS) 방법을 이용하여 측정하였다. RUS 방법은 한 개의 소형 시편으로 9개의 독립변수를 가진 사방정계(orthorhombic) 탄성계수를 간단한 실험으로 측정 가능함을 보여주었다. SiC 강화재 부피분율 변화에 따른 탄성계수를 측정하였는데 이 경우 초기 추정 탄성계수를 구하기 위해서 부피 분율에 따른 미세조직 사진으로부터 강화재의 형상(aspect ratio)과 방향을 고려한 유효 aspect ratio 개념을 도입하였고. Mori-Tanaka 이론식에 의한 계산결과를 이용하였다. 이로부터 계산된 공진주파수와 RUS의 측정 공진주파수 사이를 최소화함으로 정확한 탄성계수를 측정하였다. 측정된 stiffnesses로부터 공학적 탄성계수인 Young's modulus를 계산하였으며, 계산된 Young's modulus와 압출방향으로 인장 시험한 Young's modulus를 비교분석 하였다. SiC 입자의 부피분율이 증가함에 따라 탄성계수가 증가함을 나타내었고, 탄성 stiffness의 거동은 강화재가 많이 첨가될수록 횡등방성(transversely isotropic)이 강하게 나타났으며 이것은 압출공정에 의해 강화재 입자의 방향성 재배열에 기인한다. 한편 일정크기 시편에 있어서 기본 공진주파수가 강화재 부피분율에 따라 고주파수 영역으로 이동하는 현상이 관찰되었으며, 이로 부터 비파괴적으로 강화재 부피분율을 예측할 수 있는 가능성을 제시하였다.