• 대한기계학회논문집A
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• 제24권2호
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• pp.496-505
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• 2000

A semi-infinite parallel crack propagated with constant velocity in two bonded anisotropic strip under anti-plane clamped displacement is analyzed. Using Fourier integral transform a Wiener-Hopf equation is derived. By solving this equation the asymptotic stress and displacement fields near the crack tip are determined, where the results give the more general expression applicable to the extent of the anisotropic material having one plane of elastic symmetry for the parallel crack. The dynamic stress intensity factor and energy release rate are also obtained as a closed form, which are the results applicable to the problem both of dynamic and static crack under the same geometry as this study. The stress intensity factor approaches zero at the critical crack velocity which is less than the shear wave velocity, but in typical case of isotropic or orthotropic material agrees with the velocity of shear wave. Also a circular shear stress around crack tip is considered, from which the stress is shown to be approximately symmetric about the horizontal axis. Referring to the maximum stress criteria, it could be shown that a brenched crack is formed by crack growth as crack velocity increases.

• Structural Engineering and Mechanics
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• 제58권5호
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• pp.783-797
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• 2016

Exact solutions for stresses, strains, and displacements of a perforated rectangular plate by an arbitrarily located circular hole subjected to both linearly varying in-plane normal stresses on the two opposite edges and in-plane shear stresses are investigated using the Airy stress function. The hoop stress occurring at the edge of the non-central circular hole are computed and plotted. Stress concentration factors (the maximum non-dimensional hoop stresses) depending on the location and size of the non-central circular hole and the loading condition are tabularized.

• 대한기계학회논문집
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• 제11권1호
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• pp.88-96
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• 1987

본 논문에서는 Maubach의 방법에 내재된 불합리한점을 보완하고자 Fig.1(b)와 같이 .iota.=0인 곳에서 속도구배를 ㄹ변환하여 마찰계수와 조도함수를 계산하였다. 이 방법에 의해 얻어진 속도분포에서는 .iota.=0인 곳에서 속도구배에 불연적성이 일어나지 않는다.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.217-222
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• 2015

In this paper, a study was conducted for the optimization through shear web of shape the Edison program in wind power blade. We measured the displacement and stress distribution through two optimization methods to select the model with the smallest displacement and stress values. Before running the analysis, We try to find the inflection point through the shear web of the model and then analyze by introducing the geometric nonlinearity. The first optimization variables are introduced by the pitch angle and three web shapes. Third model such a honeycomb structure is good way to get an advantage for bending test. According to a method of previous optimization, third model is chosen and then the thickness of the web and blade as a variable is introduced, it is extracted as a result of displacement and the maximum stress per mass.

• KSBB Journal
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• 제5권4호
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• pp.391-396
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• 1990

4.0$\times$10-3 (IU/cells/day) of maximum specific scu-PA production, which was higher than those by a 75$\textrm{cm}^2$ T-flask and conventional perfusion systems, was maintained by tube-type bioreactor at 0.35 (1/h) of perfusion rate corresponding to 0.15 (dynes/$\textrm{cm}^2$) of shear stress. The production of scu-PA is also increased as shear stress was slowly increased, which is similar to natural human blood circulation. The tube reactor proves that there may be no limitation of oxygen supply by showing 1.0 (1/h) of oxygen transfer coefficient at steady state and this system yields much lower shear stress of 0.3(dynes/$\textrm{cm}^2$) than that of 5-8(dynes/$\textrm{cm}^2$) by conventional agitation systems.

• Archives of Pharmacal Research
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• 제19권3호
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• pp.183-190
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• 1996

There are a wide variety of semi-solid ointments used for healing the skin diseases, whose therapeutic and skin penetration abililties may greatly differ from one another depending on the compositions of ointment vehicles. A computer optimization technique was applied to obtain the optimum formula of o/w type ointment giving the in vitro maximum absorption rate through hairless rat skin membrane. Some of the formulations were selected to find out a relationship between skin penetration of ointment and its Theological characteristics. The experimental value of absorption rate obtained from the ointment by optimum formula agreed well with the theoretical value obtained from a polynomial regression analysis, Three kinds of ointments selected among 15 formulations were obtained with a concentric cylinder type rheometer (Model; Rheolab SM-HM Physica, Germany) at 20, 30, 40 and $50^{\circ}C$ for rheograms of rhelolgical properties of o/w type ointments. As the temperature was raised, all products showed a decrease in both shear stress and yield values. The higher skin penetration, the lower shear stress showed.

• 한국기계연구소 소보
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• 통권17호
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• pp.75-82
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• 1987

Shrink-rings (Stress-rings) are used in the fabrication of powder compaction dies to increase the allowable compaction pressures for a given die material. Optimum Procedures are used to insure that the stress distributions in the die and stress-rings ultilize fully the strength available in each of the die elements. Two criteria for the optimum die design are used: Maximum shear stress limit for one-piece dies and zero tensile stress limit for combined dies. Examples for each case are presented in this paper.

• 대한기계학회논문집A
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• 제23권6호
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• pp.912-921
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• 1999

Shear stress acting on the arterial wall by blood flow is an important hemodynamic factor influencing blocking of blood vessel by thickening of an arterial wall. In order to study the effects of wall elasticity on the wall shear rate distribution in an artery-divergent graft anastomosis, a rigid and a elastic model are manufactured. These models are placed in a pulsatile flow loop, which can generate the desired flow waveform. Flow visualization method using a photochromic dye is used to measure the wall shear rate distribution. The accuracy of measuring technique is verified by comparing the measured wall shear rate in the straight portion of a model with the theoretical solution. Measured wall shear rates depend on the wall elasticity and flow waveform. The mean and maximum shear rate in the elastic model are lower than those in rigid model, and the decreases are more significant near the end of a divergent tube. The reduction of mean and maximum of wall shear rate in an elastic model are up to 17 percent.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.703-704
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• 2002

The two major problems related to the blood flow in a floating type polymer valve are thrombus formation and hemolysis. It is well known that the shear stress in the fluid and flow separation around the valve are blamed for such disastrous phenomena. In this viewpoint, through study of the flow field around the valve is imperative to improve design of the valve. The aim of this study is to investigate the fluid flow around a floating type polymer valve. The numerical method employed in this study is the finite element software called ADINA. Incompressible viscous flow is assumed for blood using the assumption of Newtonian fluid. In this study, two prominent features of the axisymmetric flow around the floating type polymer valve are observed: jet-like flows observed near the gap between the conduit and the valve, and recirculating flow downstream of the valve. We also provided a detailed description of shear stress field according to the variation of flow conditions. The shear stress in fluid has its maximum value near the gap between the valve and the conduit.

• 동력기계공학회지
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• 제5권1호
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• pp.21-26
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• 2001

This paper represents the turbulent intensity, the turbulent kinetic energy and Reynolds shear stress in the X-Y plane of cone type swirl gas burner measured by using X-probe from the hot-wire anemometer system. The experiment is carried out at flowrate 350 and $450{\ell}/min$ respectively in the test section of subsonic wind tunnel. The turbulent intensity and the turbulent kinetic energy show that the maximum value is formed in the narrow slits distributed radially on the edge of a cone type swirl burner, hence, the combustion reaction is anticipated to occur actively near this region. And the turbulent intensities ${\upsilon}\;and\;{\omega}$ are disappeared faster than the turbulent intensity u due to the inclined flow velocity ejecting from the swirl vanes of a cone type baffle plate of burner. Moreover, the Reynolds shear stress $u{\upsilon}$ is distributed about three times as large as the Reynolds shear stress $u{\omega}$ in the outer region of the cone type gas burner.