• 한국전산유체공학회지
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• 제9권4호
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• pp.20-33
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• 2004

In this study a stretching-mapping method is proposed for calculating the materials' stretching exponents, which are to be used in quantification of the mixing effect. In this method, the mapping tensor associated with the deformation of each fluid material is first obtained. Then deformations of a lot of materials are obtained by applying the mapping tensor. The local stretching rates and their space-average values are next computed with the mapped deformations. Application to a simple time-periodic flow within a cavity shows that the method is indeed effective compared with the conventional method; i.e. the mapping method is fast and yields the same results as the conventional one.

• 대한기계학회논문집
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• 제17권5호
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• pp.1132-1137
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• 1993

본 연구에서는 특수하게 제작된 펀치형상을 갖는 평면변형장출실험에 의한 스탬핑성형성 평가기술(RIST-PSST)의 개요에 대하여 논하고 돔장출 실험결과와 비교하여 본 방법의 특징을 검토하였다.

• 오토저널
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• 제15권2호
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• pp.121-129
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• 1993

Plane strain punch stretching test (PSST) was developed to evaluate stamping formability of sheet materials. In this test, the rectangular specimen of sheet material is uniformly stretched up to fracture by raising a specially designed punch to certainly assure plane strain stretching deformation along the longitudinal direction of the specimen. The stamping formability was evaluated by limit punch height(LPH) in plane strain punch stretching test compared to limit dome height(LDH) in hemispherical punch stretching test. LPH-value in PSST well ranks the stamping formability of various material and correlates with press performance. Moreover by using ultrasonic thickness gauge the plane strain intercept-limit plane strain(FLCo)-in forming limit curve can be accurately determined from thickness measurement around the fracture area. The FLCo derived from thickness measurement well correlates with the results from circle grid analysis for the deformed circle grid marked on the surface of the specimen.

• 한국전산유체공학회지
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• 제9권4호
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• pp.55-63
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• 2004

The three-dimensional Stokes flow within a staggered screw channel is obtained by using a finite volume method. The geometry is intended to mimic the single screw extruder having staggered arrangement of flights. The flow solution is then subjected to the analysis of the stirring performance. In the analysis of the stirring performance, the stretching-mapping method developed by the author is employed for calculating the materials' stretching exponents, which are to be used in quantification of the mixing effect. The numerical results Indicate that the staggered geometry gives indeed far much better stirring-performance than the standard (nonstaggered) flight geometry. It was also shown that care must be given to the selection of the basis planes for evaluating the local stretching rate, and it turns out that the best method (H-method) has its basis plane just on the half way between the past and future evolution of fluid particles subjected to the defromation. In evaluating the stretching exponent, the expansion ratio must be considered which is one of the characteristic differences of the actual three-dimensional flows from the two-dimensionmal counterparts. The larger axial pressure-difference causes in general the smaller stirring performance while the flow rate is increased. The smaller channel length also increases the stirring performance.

• The Journal of Korean Physical Therapy
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• 제14권4호
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• pp.423-440
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• 2002

The purpose of this study is to investigate the conception and developmental process of stretching in sports physical therapy. This study is to find conception of stretching, feature and effect, principles and fundamental rule, consideration of enforcement and developmental process in order to use the basic material which is very helpful in the every field and the scene of sports needing stretching. Flexibility is the ability to move muscles and joints through their full ranges of motion. Flexibility is developed by stretching. About player who insufficiency of flexibility, patient and disabled person who restrict of range of motion, older adult who reduce of flexibility, promote of flexibility for upgrading stability and efficiency of body on the based of scientific principles is completed by stretching. The method of stretching has been developed with passive stretching, CR, PNF stretching, PIC stretching, MET stretching in the order. The effects that we can get through stretching are as follows : 1. Enhance physical fitness. 2. Optimize learning, practice and performance of many types of skilled movement. 3. Increase mental and physical relaxation. 4. Promote development of body awareness. 5. Reduce risk of joint sprain or muscle strain. 6. Reduce risk of back problem. 7 Reduce muscular soreness. 8. Reduce the severity of painful menstruation for female athletes. 9. Reduce muscular tension. 10. Advance recognition of body.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.317-318
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• 2009

In this paper, we observed stretching of carbon nanotube (CNT) aggregates driven by the electric filed in a nematic liquid crystal (LC) medium. The CNT aggregates started to stretch above a threshold filed which is $1.5\;V/{\mu}m$ and the original CNT length which is $1.7{\mu}m$ was stretching up to $19.2\;{\mu}m$ at $3.5\;V/{\mu}m$ electric filed. When the CNT aggregates became to stretching, the width and length of CNT aggregates became narrow and long, respectively. The original morphology of the CNT aggregates was restored upon removal of filed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.170-170
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• 2010

In this paper, we observed stretching of single-wall carbon nanotubes (SWCNTs) aggregates driven by the in-plane field in a homogeneously aligned nematic liquid crystal (LC) medium. Aggregates of SWCNTs started to stretch above the 0.5 V/${\mu}m$ and stretched up to $1.83\;{\mu}m$ from original size with $0.74\;{\mu}m$ at 3.5 V/${\mu}m$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.59-62
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• 1994

Tact Electrical conductivity. optical absorption spectra of poly(p-phenylene vinylene) and their dependence on stretching are discussed in detail. The conductivity in the parallel direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching is higher over one order in magnitude than that in the perpendicular direction to the stretching. The photocurrent spectrum for the ligh polarized parallel to the chain direction is much enhanced in lower photon energy compared with that for the light polarized perpendicular to that direction. The result may be originated in the difference of energies which is needed to photogenerate carriers wi th the light polarized parallel and perpendicular to the chain stretched direction.

• Structural Engineering and Mechanics
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• 제84권6호
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• pp.783-798
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• 2022

This study attempts to investigate the impact of thickness stretching and nonlinear hygro-thermo-mechanical loading on the bending behavior of FG beams. Young's modulus, thermal expansion, and moisture concentration coefficients vary gradually and continuously according to a power-law distribution in terms of the volume fractions of the constituent materials. In addition, the interaction between the thermal, mechanical, and moisture loads is involved in the governing equilibrium equations. Using the present developed analytical model and Navier's solution technique, the numerical results of non-dimensional stresses and displacements are compared with those obtained by other 3D theories. Furthermore, the present analytical model is appropriate for investigating the static bending of FG beams exposed to intense hygro-thermo-mechanical loading used for special technical applications in aerospace, automobile, and civil engineering constructions.

• Steel and Composite Structures
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• 제15권2호
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• pp.221-245
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• 2013

This paper presents an analytical solution to the thermomechanical bending analysis of functionally graded sandwich plates by using a new hyperbolic shear deformation theory in which the stretching effect is included. The modulus of elasticity of plates is assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. The effects of functionally graded material (FGM) layer thickness, volume fraction index, layer thickness ratio, thickness ratio and aspect ratio on the deflections and stresses of functionally graded sandwich plates are investigated.