• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.1
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• pp.176-187
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• 2001

Most bridges have expansion joints to accommodate thermal expansion and contraction without inducing large forces in the bridges. To evaluate the effects of earthquake-induced at expansion joints of concrete bridges, the first part of this paper deals with a collinear impact between concrete segments, which have the same cross section but different lengths. Especially, impact force, momentum, strain energy and kinetic energy are formulated in mathematically. These results are then used in the second part of this paper to simulate a realistic yet simple analysis of seismic pounding in concrete bridges. Analysis of seismic pounding in idealized concrete bridges is carried out by using a simple lumped-mass model and rationally determined values of the coefficient of restitution and the duration of impact.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.1
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• pp.38-44
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• 2007

Using the mathematical model suggested by Bennet et al.(1992), the reflection and transmission coefficients by a circular pile breakwater has been investigated in the framework of potential theory. Flow separation due to sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of exact energy loss coefficient is critical to enhance the reliability of mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code. The energy loss coefficient can be obtained from the pressure difference between upstream and downstream. Energy loss coefficient is the function of porosity and the relation equation between them is suggested throughout the curve fitting processing. To validated the suggested relation, comparison between the analytical results and the experimental results is made for four different porosities with good agreement.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.181-187
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• 1991

The muscarinic antagonist 1-[benzilic 4, 4'-$[^3H]$ QUINUCLIDINYL BENZILATE $([^3H]$ QNB) bound to a single class of muscarinic receptors with high affinity in rabbit ileal membranes. The $K_D\;and\;B_{ max}$ values for $([^3H]$ QNB calculated from analysis of saturation isotherms were 52.5 pM AND 154 fmol/mg, respectively. Chlopheniramine (CHP), histamine $H_1$ blocker, increased $K_D$ vlue for $([^3H]$QNB without affecting the binding site concentrations and Hill coefficient. The $K_i$ value of CHP for inhibition of $([^3H]$QNB binding in ileal membranes was 1.44\mu{M}$ and the pseudo-Hill coefficient for CHP was close to unit. In the functional assay carbachol, muscarinic agonist, increased the contractile force of ileum with $ED_{50}$ value of $0.11\mu{M}$. CHP caused the rightward shift of the dose-response curve to carbachol. The $pA_2$ value of CHP determined from Schild analysis of carbacholinduced contraction was 5.77 and the slope was unity indicating competitive antagonism with carbachol. The dissociation constant $(K_i)$ of CHP obtained in competitive experiments with $([^3H]$ QNB was similar to the $K_A$ value (1.69 \mu{M)}$ of CHP as inhibitor of carbachol induced contraction in rabbit ileum. This result suggest that the binding of $H_i$ blocker. CHP, vs $([^3H]$QNB to muscarinic receptors in ileal membranes represents an interaction with a receptor of physiological relevance.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.179-182
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• 2004

This paper deals with a new mathematical formulation of nonlinear wave profile based on Banach fixed point theorem. As application of the formulation and its solution procedure, some numerical solutions was presented in this paper and nonlinear equation was derived. Also we introduce a new operator for iteration and getting solution. A numerical study was accomplished with Stokes' first-order solution and iteration scheme, and then we can know the nonlinear characteristic of Stokes' high-order solution. That is, using only Stokes' first-oder(linear) velocity potential and an initial guess of wave profile, it is possible to realize the corresponding high-oder Stokian wave profile with tile new numerical scheme which is the method of iteration. We proved the mathematical convergence of tile proposed scheme. The nonlinear strategy of iterations has very fast convergence rate, that is, only about 6-10 iterations arc required to obtain a numerically converged solution.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.24-29
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• 2002

In this paper, the microstructure and the dielectric properties of Sr$\_$1-x/CaxTiO$_3$(0$\leq$x$\leq$0.2)-based grain boundary layer ceramics were investigated. The sintering temperature and time were 1420∼152 0$\^{C}$ and 4 hours in N$_2$ gas, respectively. The average grain size and the lattice constant were decreased with increasing content of Ca, but the average grain size was increased with increase of sintering temperature. The second phase foamed by the thermal diffusion of CuO from the surface leads to verb high apparent dielectric constant, $\xi$$\_$r/>50000 and low dielectric loss, tan$\delta$<0.05. X-ray diffraction patterns of Sr$\_$1-x/CaxTiO$_3$ exhibited cubic structure, and the peaks shifted upward and the peak intensity were decreased with x. This is due to the lattice contraction as Sr is replaced by Ca with a smaller ionic radius. The specimens treated thermal diffusion for 2hrs in 1150$\^{C}$ exhibited nonlinear current-voltage characteristic, and its nonlinear coefficient(a) was overt 7.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.5
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• pp.745-756
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• 1999

The purpose of this study is to investigate the characteristics of the clothing consumption expenditures by the business cycles in Korea during the period of first quarter of 1979 to second quarter of 1998. Business cycles were examined using data GNP from the National Accounts published by the Bank of Korea and clothing expenditures from the monthly statistics of Korea published by the National Statistical Office of Korea. Data were analyzed by regression analysis standard deviation sample cross-correlation coefficient and skewness statistics. The main results are as follows. 1. During the period of 1979.I-1998.II GNP and per-person consumption expenditures for clothing and shoes have continuously increased except during 1980 and the recent depression of the national economy. Clothing expenditures dropped severely during the two recent depression of the national economy. Clothing expenditure dropped severely during the two depression periods. Clothing expenditures were the highest in the fourth quarter and the lowest in the third quarter of the year. 2. According to the results of the regression analysis the business cycles had a significant influence on the clothing expenditures. the volatility of the clothing expenditure was 2.60 times higher than that of the business cycles. 3. Clothing expenditures displayed procyclical fluctuation and coincident movement to the business cycles. Also clothing expenditures showed an unsymmetric behavior over the expansion phases and contraction phases of the business cycles. That is the clothing expenditures increased slowly in the expansion phases and decreased quickly and severely in the contraction phases of the business cycles.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.59-66
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• 2011

Purpose: The objective of this study was to evaluate the inter- and intra-examiner reliability of ultrasonography (US) for measuring the thicknesses and cross-sectional area of the longus colli muscle (LCM) in healthy subjects. Methods: Twenty-five healthy adults participated in this study as subjects and two examiners attended to the study. LCM size was measured at the level of the thyroid cartilage. All subjects were randomly allocated to one of the three different methods. Method 1 was that the examiner A conducts the first measurement and one hour later conducts the second measurement and twenty four hours later conducts the third measurement, respectively. Method 2 was that the examiner B conducts the measurements in the same way as the examiner A. Method 3 was that the examiners A and B randomly conduct the measurements twice at an interval of one hour. Results: The intra-class correlation coefficient (ICC) for the intra-examiner reliability ranged from 0.78 to 0.98 at rest and 0.57 to 0.98 during contraction for the examiner A. The $ICC_{3,3}$ for the intra-examiner reliability ranged from 0.60 to 0.96 at rest and 0.57 to 0.92 during contraction for the examiner B. The $ICC_{2,3}$ for the inter-examiner reliability ranged from 0.80 to 0.91 at rest and 0.84 to 0.93 during contraction. Conclusion: The findings of this study indicate that US is a reliable method for measuring the LCM size.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.73-76
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• 2009

Autogenous shrinkage of high-strength mass concrete is affected high temperature history. So to evaluate autogenous shrinkage of high-strength mass concrete accurately, thermal expansion in it should be removed. In this study, compensated autogenous shrinkage was calculated after gathering thermal expansion coefficient at early age experimentally. As a result of the study. Autogenous shrinkage of mass specimen (300 ${\times}$ 300 ${\times}$ 300mm) was remarkably higher than it of standard specimen (100 ${\times}$ 100 ${\times}$ 400mm). So it was found that compensation on thermal expansion should in evaluating autogenous shrinkage of high-strength mass concrete. And this study shows results on opc and similar own contraction, if used retarder.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1603-1612
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• 1996

The pressure loss coefficient of Newtonian and non-Newtonian fluids such as water, aqueous solutions of Carbopol-934 and Separan AP-273 and blood in the stenotic tubes are determined experimentally and numerically. The numerical analyses for flows of non-Newtonian fluids in the stenotic tubes are conducted by the finite element method. The effect of the contraction ratio and the ratio of length to diameter on the pressure drop are investigated by the experiments and numerical analysis. The pressure loss coefficients are significantly dependent upon the Reynolds number in the laminar flow regime. As Reynolds number increases, the pressure loss coefficients of both Newtonian and non-Newtonian fluids decrease in the laminar flow regime. As the ratio of length to diameter increases the maximum pressure loss coefficient increases in the laminar flow regime for both Newtonian and non-Newtonian fluids. Newtonian fuid shows the highest values of pressure loss coefficient and blood the next, followed by Carbopol solution and Separan solution in order. Experimental results are used to verify the numerical analyses for flows of Newtonian and non-Newtonian fluids. Numerical results for the maximum pressure loss coefficient in the stenotic tubes are in fairly good agreement with the experimental results. The relative differences between the numerical and experimental results of the pressure loss coefficients in the laminar flow regime range from 0.5% to 14.8%.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.39-53
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• 2018

Generally, the total ventilation resistance coefficient in a tunnel consists of inlet/outlet loss coefficient, wall friction coefficient, and other loss coefficient caused by sudden expansion and contraction of cross-section, etc. For the tunnel before opening, when the running ventilation fan is stopped, the wind speed in the tunnel is reduced by the total ventilation resistance drag. The velocity decay method is comparatively stable and easy to estimate the wall friction coefficient in the pre-opening tunnel. However, the existing study reported that when the converging wind speed is a negative value after the ventilation fan stops, it is difficult to estimate the wall friction coefficient according to the velocity decay method. On the other hand, for the operating tunnel in which the piston effect acts, a more complex process is performed; however, a reasonable wall friction coefficient can be estimated. This paper aims at suggesting a method to minimize the measurement variables of the piston effect and reviewing a method that can be applied to the operating tunnel. Also, in this study, a new method has been developed, which enables to calculate an variation of the piston effect if the piston effect is constant with a sudden change of external natural wind occurring while the wind speed in the tunnel decreases after the ventilation fan stops, and a programming logic has been also developed, which enables dynamic simulation analysis in order to estimate the wall friction coefficient in a tunnel.