• Atmosphere
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• v.25 no.4
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• pp.659-667
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• 2015

In this study, sensitivity of inflow wind speed and turbulent Schmidt number to pollutant dispersion in an urban street canyon is investigated, by comparing CFD-simulated results to wind-tunnel results. For this, we changed systematically inflow wind speed at the street-canyon height ($1.5{\sim}10.0m\;s^{-1}$ with the increment of $0.5m\;s^{-1}$) and turbulent Schmidt number (0.2~1.3 with interval of 0.1). Also, we performed numerical experiments under the conditions that turbulent Schmidt numbers selected with the magnitude of mean kinetic energy at each grid point were assigned in the street canyon. With the increase of the inflow wind speed, the model underestimated (overestimated) pollutant concentration in the upwind (downwind) side of the street canyon because of the increase of pollutant advection. This implies that, for more realistic reproduction of pollutant dispersion in urban street canyons, large (small) turbulent Schmidt number should be assigned for week (strong) inflow condition. In the cases of selectively assigned turbulent Schmidt number, mean bias remarkably decreased (maximum 60%) compared to the cases of constant turbulent Schmidt number assigned. At week (strong) inflow wind speed, root mean square error decreases as the area where turbulent Schmidt number is selectively assigned becomes large (small).

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.75-76
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• 2015

Lifted flame stabilization mechanism can be explained with constant Schmidt number from the equation of $H^{\ast}_L/d^2_o=const{\times}v_e^{(2Sc-1)/(Sc-1)}$. In this research, a method of local Schmidt number was applied in order to measure edge flame propagation velocities, and edge flame propagation velocity was calculated from the trend between lift-off height and nozzle flow rate.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.139-150
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• 2006

A study has been made of the Schmidt hammer rebound test for the estimation of engineering and physical characteristics of sedimentary rocks. As there is no universal formular for the estimation of rock strength due to geological conditions, in this study only sedimentary rocks are adopted to testing. The aim of study is to make the information more meaningful and useful for engineers and contractors by providing rapid, cheap and easy method. The obtained parameters were correlated and regression equations were established among Schmidt hammer rebound number, uniaxial compressive strength, tangent Young's modulus, indirect tensile stress, water absorption and porosity of rocks with high coefficients of correlation with each other.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.601-609
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• 2018

Steel bolts are used in the construction industry for a large variety of applications that range from fixing permanent installations to temporary fixtures. In the past much research has been focused on developing destructive testing techniques to estimate their pull-out load carrying capacity with very little attention to develop non-destructive techniques. In this regards the presented research work details the combined use of ultrasonic pulse velocity and Schmidt hammer tests to identify anchor bolts with faculty installation and to estimate their pull-out strength by relating it to the Schmidt hammer rebound value. From experimentation, it was observed that the load capacity of bolt depends on its embedment length, diameter, bond quality/concrete strength and alignment. Ultrasonic pulse velocity test is used to judge the quality of bond of embedded anchor bolt by relating the increase in ultrasonic pulse transit time to the presence of internal pours and cracks in the vicinity of steel bolt and the surrounding concrete. This information combined with the Schmidt hammer rebound number, R, can be used to accurately identify defective bolts which resulted in lower pull-out strength. 12 mm diameter bolts with embedment length of 70 mm and 50 mm were investigated using constant strength concrete. Pull-out load capacity versus the Schmidt hammer rebound number for each embedment length is presented.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.909-912
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• 2001

This paper presents the validities of the removal time of side forms considering the relationship between rebound number of P type schmidt hammer and compressive strength. According to test results, compressive strength of 40% of W/C at 12 hours shows 16kgf/$cm^{2}$ and 50% of W/C at 15 hours, 13kgf/$cm^{2}$. Rebound number at 9 hours after casting shows 13 and 9 (W/C 40% and W/C 50%). According to the regression analysis, rebound number of P type schmidt hammer to gain 50kgf/$cm^{2}$ of is estimated 20.1. It is thought that desirable rebound number of P type schmidt hammer to gain 50kgf/$cm^{2}$ is determined 25 considering safety factor.

• Journal of Korea Water Resources Association
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• v.47 no.8
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• pp.703-715
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• 2014

This study aims to investigating the effect of Schmidt number (${\sigma}_c$) on sediment suspension and hydrodynamics calculation. The range of ${\sigma}_c$ is also studied based on the flux Richardson number ($Ri_f$) and gradient Richardson number ($Ri_g$). Numerical experiments are carried out by 1 dimensional vertical model. Both cohesive and non-cohesive sediments are tested under the conditions of pure current and oscillatory flow. The turbulence damping effect due to sediment suspension is examined considering ${\sigma}_c$ as a constant for the damping effect. The results of this study show the consistent effect of ${\sigma}_c$ on sediment suspension regardless of hydrodynamic condition. It is also found that the model overestimates the flow velocity and turbulent kinetic energy when the damping effect is not considered. Under the conditions of $Ri_f$ and $Ri_g$ causing density stratification, it is known that the vertical mixing of sediment is reasonably calculated in the range of ${\sigma}_c$ from 0.3 to 0.5.

• Korean Journal of Veterinary Research
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• v.49 no.4
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• pp.273-278
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• 2009

Neurofascin, one of the members of L1CAM, has been known to have some important roles during the development of nerve fibers. In order to investigate the role of neurofascin associated with the formation of Schmidt-Lantermann incisure in the sciatic nerve, the localization of neurofascin was studied with electron microscopy, immuno-fluorescence and immuno-electron microscopy. In the electron microscopy, the first formation of Schmidt-Lantermann incisure was checked at postnatal day 6 and the complete form of incisures traversing the whole myelin sheath began to be observed at postnatal day 8. In the immunofluorescence, neurofascin immunoreactive Schmidt-Lantermann incisures were first checked at postnatal day 6 and dramatically increased with aging by postnatal day 56. In the immunoelectron microscopy, neurofascin immunoreactive gold particles at the incisure forming sites were first observed at postnatal day 6 and the number of gold particles was increased as the animal was getting old by postnatal day 56. According to the present study, neurofascin is likely to have some relationships with Schmidt-Lantermann incisure formation.

• Computers and Concrete
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• v.15 no.3
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• pp.473-484
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• 2015

In this study, the availability of Schmidt hammer has been investigated as a reliable method to determine the quality of concrete in irrigation networks. For this purpose, the 28-day compressive strength of concrete material used in the construction irrigation channel of Bafra lowland, which is one of the most fertile plains in Turkey was examined by means of concrete compression and as well as concrete Schmidt hammer in laboratory conditions. This study was carried out on cylindrical samples to represent the everyday concrete party ($150m^3$) produced by contractor firm as 3 replications. The statistical analysis of experimental data showed that the correlations between the values of 28-day compressive strength of Schmidt hammer and the rebound number was found to be 0.98. Differences of the compressive strength between compression testing and Schmidt hammer were statistically significant at P<0.01. In this context, it was found that the reliability of compressive strength of the concrete compression test are excellent, also the reliability of compressive strength of Schmidt hammer are fair in assessing the quality of concrete irrigation channels.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.837-845
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• 2005

In this paper, an investigation on high-Schmidt number (Sc=1670) mass transfer in turbulent flow around a rotating circular cylinder is carried out by Direct Numerical Simulation. The concentration field is computed for three different values of low Reynolds number, namely 161, 348 and 623 based on the cylinder radius and friction velocity. Statistical study reveals that the thickness of Nernst diffusive layer is very small compared with that of viscous sub-layer in the case of high Sc mass transfer. Strong correlation of concentration field with streamwise and vertical velocity components is observed. However, that is not the case with the spanwise velocity component. Instantaneous concentration visualization reveals that the length scale of concentration fluctuation typically decreases as Reynolds number increases. Statistical correlation between Sherwood number and Reynolds number is consistent with other experiments currently available.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.199-207
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• 2008

As infrastructures are being deteriorated, nondestructive evaluation of existing structures and construction quality control are increasingly demanded. The importance of predicting compressive strength of concrete structure is also gradually increasing in construction industry. The estimation of concrete compressive strength is a critical factor of the construction management and quality control. This study has been conducted using Schmidt hammer test and Impact echo method, which are nondestructive test methods for the comparison of the concrete compressive strength. It is focusing to examine the relationship between compressive strength of concrete and rebound number by Schmidt hammer test result by Impact echo method. It was found that concrete compressive strength and rebound number have a close correlation.