• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.564-571
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• 2002

Three-dimensional numerical analysis of the turbulent premixed flame propagation in a constant volume combustion chamber is performed using the KIVA-3V code (Amsden et. al. 1997) by the flame surface density (FSD) model. A simple near-wall boundary condition is eaployed to describe the interaction between turbulent premixed flame and the wall. A mean stretch factor is introduced to include the stretch and curvature effects of turbulence. The results from the FSD model are compared with the experimental results of schlieren photos and pressure measurements. It is found that the burned mass rate and flame propagation by the FSD model are in reasonable agreement with the experimental results. The FSD combustion model proved to be effective for description of turbulent premixed flames.

• Biomedical Science Letters
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• v.12 no.2
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• pp.119-125
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• 2006

In relation to the tissue engineering, the cellular responses to the morphology of the scaffold surface are interesting topics. Human ligament fibroblasts (HLFs) were cultured on the micrpatterned silicone substrates subjected to cyclic stretch to simulate ligament motion. Groove and ridge width of silicone substrates was 10/50, 20/50, 20/10, and 20/20 ${\mu}m$ (groove/ridge ${\mu}m$) with a depth of $3{\mu}m$. Strain was applied over two days for 4 hours per day with a frequency of 0.5 Hz with the magnitudes of 4 or 8%. The purpose of this study was to evaluate ligament fibroblast alignment and cellular responses in relation to the pattern of microgrooved surface and stretching magnitude. Ligament fibroblasts in the microgrooved surface were elongated and aligned parallel to the microgrooves under no stretch. Uniaxial cyclic stretch induced cellular activities and their orientation rise in cellular response and the cells showed alignment and elongation perpendicular to the direction of the stretch. Biochemical analyses showed that the best cellular response was found on the $20/50{\mu}m$ under 8% stretch. The surface morphology and mechanical stretching were found to contribute to increase of proliferation, collagen production.

• Textile Coloration and Finishing
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• v.23 no.4
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• pp.233-240
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• 2011

A fineness range of 150 Nm-170 Nm has recently been applied to produce much finer wool products, so that processing techniques for the wool fabrics have been developed very rapidly. However, the worsted wool-like technique using polyester fiber has not been still implemented in general processing technique. Therefore, this research is to develop materials of side-by-side type with high finess, high shrinkage and stretchability. The mechanical properties of the produced fabrics were analyzed and the fundamental information were obtained for the new worsted wool-like products. The physical properties of a latent crimped yarns of side-by-side type with stretch function are analyzed. Also the mechanical properties of five kinds of fabrics are analyzed, which are produced with non-circular shape(+type) warp yarns of a twist of 1000(T/M) and with two kinds of latent weft yarns of a twist of 1000 T/M and DTY respectively.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1922-1927
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• 2005

This paper describes the mechanism of a new biped machine capable of doing human-robot cooperation work. The biped machine, WABIAN-2 is made of two seven degrees of freedom (DOF) legs, a two DOF waist and no DOF trunk. Its leg system consists of two three DOF ankles, two one DOF knees and two three DOF hips to deal with various walk motions. Its height is about 1.2[m], and its weight is 40[kg]. It is designed with large movable range as a human. Also, a knee stretch walk pattern generation for the biped machine to perform natural walk like a human is discussed in this paper. Its leg motion is compensated by using the motion of its waist. Basic knee stretch walk experiments using WABIAN-2 are conducted on the plane, and the validity of its mechanism and walk pattern generator is verified.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.215-221
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• 2015

The elbow reflex, a principal reflex in the upper extremity, plays an important role in the diagnosis of cervical spine syndromes. In this study, the muscle activations of brachial biceps and triceps, and the kinematics of upper extremities were predicted using an activation model for the stretch reflex. The muscle activations that equated the simulation results estimated by the analysis model with the experimental results were obtained first, and the activations obtained from the simulations were compared with the electromyography signals obtained from the experiments, for model validation. The root mean squares error of the joint angles (obtained from experiments and simulation using the suggested model) was 0.056, a value that is half of that obtained using the previous model. This demonstrates that the suggested model corresponded well with the actual reflex.

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.357-362
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• 2006

This study is to evaluate the objective sensibility of the commercial lining fabrics. Five kinds of the linings were collected by adding taffetas with four kinds of fibers (polyester, nylon, rayon, and acetate) to one polyester stretch fabric. The six basic mechanical and hand properties were studied by using KES-FB system (Kawabata Evaluation System). The result of measuring the mechanical properties shows that polyester has high bending rigidity (B), that polyester-stretch has a high value of linearity of load-extension curve (LT), tensile energy (WT), tensile resilience (RT), and coefficient of friction (MIU) and a low value of bending rigidity(B), shear property, and geometrical roughness (SMD). The nylon has a high value of bending rigidity (B), shear property, and compression resilience (RC). The rayon has a high value of coefficient of friction (MIU) and linearity of compression-thickness curve (LC) and a low value of shear property, and the acetate has a low value of shear property. The result of hand value shows that polyester, nylon, and acetate are a high value of KOSHI (stiffness), NUMERI (smoothness), and FUKURAM (fullness & softness), and they feel stiff and massive, that rayon has a low value of NUMERI and FUKURAMI. The total result of hand value shows that polyester taffeta and polyester stretch fabric are about the same as the best material for the lining of a woman's dress for spring and summer, and the next thing is acetate, but nylon and rayon are somewhat inferior materials. This provides a fundamental data for the comfortable clothing production of a higher value-added product through the study on the mechanical and hand properties of the lining as well as the right side of fabrics.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.171-178
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• 2006

The performance in the practical combustion system including reciprocating engines and gas turbine combustors is being much governed by turbulent reacting flow that is often analyzed by both a laminar flamelets concept and flame interaction. The characteristics of laminar flame interaction have been investigated numerically to provide basic understanding of wrinkled turbulent flames under concentration interaction resulting from inhomogeneity in fuel-air mixing, especially focused on the transition of flame characteristics such as diffusion flame, partially premixed diffusion flame, and triple-layer flame by the variation in the degree of premixedness. The extinction stretch rates to the premixedness have also been obtained in this paper. The boundary defining the regime of the existence of triple-layer flames as functions of both stretch rate and premixedness has been determined which agrees well with previously reported experiment measuring OH radical concentration peaks based on PLIF.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1119-1128
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• 1990

A numerical method for analyzing non-isothermal, rigid-viscoplastic deformation problems has been presented. As an application, a stretch forming of sheet metals, including temperature effect, has been analyzed by a three-dimensional finite element method. Bishop`s step-wise decoupled method is adopted to solve thermomechanical coupling between deformation and heat transfer. Using the method, the effect of temperature on strain distribution during stretch forming is investigated. By comparison of the non-isothermal results with isothermal analysis, the importance of including temperature effects in the analysis of metal forming problems is emphasized. The predicted results were in good agreement with the existing experimental measurements at the different punch temperatures and dome heights investigated. It is also found that any increase of the punch temperature appeared to postpone the strain localization process by lowering the peak strain in the critical punch-sheet contact region and by normalizing strain distribution within the specimen.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.5
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• pp.267-274
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• 2008

Since first discovered in chick skeletal muscles, stretch-activated channels (SACs) have been proposed as a probable mechano-transducer of the mechanical stimulus at the cellular level. Channel properties have been studied in both the single-channel and the whole-cell level. There is growing evidence to indicate that major stretch-induced changes in electrical activity are mediated by activation of these channels. We aimed to investigate the mechanism of stretch-induced automaticity by exploiting a recent mathematical model of rat atrial myocytes which had been established to reproduce cellular activities such as the action potential, $Ca^{2+}$ transients, and contractile force. The incorporation of SACs into the mathematical model, based on experimental results, successfully reproduced the repetitive firing of spontaneous action potentials by stretch. The induced automaticity was composed of two phases. The early phase was driven by increased background conductance of voltage-gated $Na^+$ channel, whereas the later phase was driven by the reverse-mode operation of $Na^+/Ca^{2+}$ exchange current secondary to the accumulation of $Na^+$ and $Ca^{2+}$ through SACs. These results of simulation successfully demonstrate how the SACs can induce automaticity in a single atrial myocyte which may act as a focus to initiate and maintain atrial fibrillation in concert with other arrhythmogenic changes in the heart.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.529-534
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• 2000

A finite element analysis for a rotating cantilever beam is presented in this study. Based on a dynamic modelling method using the stretch deformation instead of the conventional axial deformation, three linear partial differential equations are derived from Hamilton's principle. Two of the linear differential equations show the coupling effect between stretch and chordwise deformations. The other equation is an uncoupled one for the flapwise deformation. From these partial differential equations and the associated boundary conditions, are derived two weak forms: one is for the chordwise motion and the other is for the flapwise motion. The weak forms are spatially discretized with newly defined two-node beam elements. With the discretized equations or the matrix-vector equations, the behaviours of the natural frequencies are investigated for the variation of the rotating speed.