• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2419-2421
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• 2008

Some of the scallops like Amesium balloti have an excellent level-swimming ability, i.e. they can swim about 20m by single level swimming with a maximum swimming velocity of about 1.6m/s in the sea. On the other hand, some species like Patinopecten yessoensis have longitudinal grooves on the upper and lower surfaces and others do not. Therefore, in the present study, we measure the lift and drag forces on a real scallop model (Patinopecten yessoensis) in a wind tunnel. Experiments are performed at the Reynolds number of 75,000 based on the maximum chord length, which is within the swimming condition of real scallop (Re = $30,000{\sim}300,000$). To see the effect of longitudinal grooves, we measure the aerodynamic forces on a scallop model by removing the grooves. With the grooves, the lift force increases at low angles of attack (${\alpha}<10^{\circ}$). The drag force increases slightly at all the attack angles considered. The lift-to-drag ratio is increased by about 10% at ${\alpha}<10^{\circ}$.

• Archives of Pharmacal Research
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• v.10 no.2
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• pp.80-87
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• 1987

To get a better insight into the exxistence and the role of a Na-Ca exchange mechanism in smooth muscle, the effect of Na substitution with sucrose on tension development, cellular Ca uptake and $^{45}Ca$ efflux was investigated using isolated cat ileal longitudinal muscle strips. Experimental results were summarized as follows;1) Exposure of the cat ileal longitudinal muscle to Na-free solution induced a contraction, and the magnitude of the contraction increased after incubation of the muscle strips with ouabain ($2{\times10^{-}5}$M) for 1hr. 2) Cellular Ca uptake in Na-free solution increased with an increase in Na content of the Na-loading media, and a linear relationship existed between tissue Na content and cellular Ca uptake for 10 min 3) After tissues were equilibrated in PSS containing $^{45}Ca$ for 2hr, cellular Ca uptake decreased with rising the external Na concentration. 4)Removal of medium Na or inhibition of the Na-K pump decreased the rate of $^{45}Ca$ efflux. These results strongly suggested that Na substitution increases cellular Ca uptake and decreases the rate of $^{45}Ca$ efflux via a Na-Ca exchange mechanism.

• Communications for Statistical Applications and Methods
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• v.29 no.1
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• pp.65-83
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• 2022

Although various statistical methods have been developed to map time-dependent genetic factors, most identified genetic variants can explain only a small portion of the estimated genetic variation in longitudinal traits. Gene-gene and gene-time/environment interactions are known to be important putative sources of the missing heritability. However, mapping epistatic gene-gene interactions is extremely difficult due to the very large parameter spaces for models containing such interactions. In this paper, we develop a Gaussian process (GP) based nonparametric Bayesian variable selection method for longitudinal data. It maps multiple genetic markers without restricting to pairwise interactions. Rather than modeling each main and interaction term explicitly, the GP model measures the importance of each marker, regardless of whether it is mostly due to a main effect or some interaction effect(s), via an unspecified function. To improve the flexibility of the GP model, we propose a novel grid-based method for the within-subject dependence structure. The proposed method can accurately approximate complex covariance structures. The dimension of the covariance matrix depends only on the number of fixed grid points although each subject may have different numbers of measurements at different time points. The deviance information criterion (DIC) and the Bayesian predictive information criterion (BPIC) are proposed for selecting an optimal number of grid points. To efficiently draw posterior samples, we combine a hybrid Monte Carlo method with a partially collapsed Gibbs (PCG) sampler. We apply the proposed GP model to a mouse dataset on age-related body weight.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1439-1447
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• 2014

Most of literatures on Korean child aggression are based on using the cross-sectional data sets. Although there is a related study with a longitudinal data set, it is assumed that the data sets measured repeatedly in the longitudinal data are mutually independent. A longitudinal data analysis for Korean child aggression is then necessary. This study is to analyze the effect of child development outcomes including academic achievement, self-esteem, depression anxiety, delinquency, victimization by peers, abuse by parents and internet using time on child aggression with Korea Welfare Panel Study data observed three times between 2006 and 2012. Since Korea Welfare Panel Study data have missing values, the missing at random is assumed. The linear mixed effect model and the restricted maximum likelihood estimation are considered.

• Journal of the Korean Home Economics Association
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• v.47 no.3
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• pp.103-118
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• 2009

This study was conducted to explore the factors that influence the development of happiness during childhood using longitudinal data obtained from the Korea Youth Panel Survey(KYPS). Specifically, the causal relationships between factors impacting the individual children, the home environment factor, and the happiness of children were examined over a 3-years-period. The subjects evaluated in this study included 2,844 children (1,524 boys and 1,320 girls) and 2,844 parents who were administered the KYPS. The data were analyzed using the SAS program. The results revealed that happiness that develops during childhood remains stable and constant, which indicates that prior happiness has a strong effect on future happiness. The individual factors affecting the children, which include schoolwork achievement and extra private education, were found to have a great influence on the development of happiness at all ages. The use of longitudinal data in this study is a new method in the field of Human Development.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.573-581
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• 2009

In the case that the average velocity within rectangular-shaped sedimentation basin is less than 1.5cm/sec, and Froude number less than $10^{-6}$, it can not be expected that the longitudinal baffle improves the sedimentation efficiency. Also, since relatively lower velocity increases the effect of geostrophic body force, asymmetric flow pattern on a plane occurs within the basin. From the results of CFD (Computational Fluid Dynamics) simulation, in the case that the highest velocity within rectangular-shaped sedimentation basin is over 1.5cm/sec, and Froude number over $10^{-6}$, it can be expected that the longitudinal baffle installed within rectangular-shaped sedimentation basin improves the sedimentation efficiency.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.120-127
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• 1998

This paper deals with the dynamic responses of the multi-span continuous bridge with longitudinal shear keys. It is motivated by a need to understand the effects of longitudinal shear keys which may be used for the reduction of the longitudinal seismic force in continuous bridges. The results show that (1) The force reduction of fixed pier is proportional to the ratio of gap size and elastic maximum displacement of the bridges without shear keys ; (2) The thermal movement has little effect on the response of the continuous bridges with shear keys. Also the simplified equation is proposed to calculate the maximum response of the continuous bridges with longitudinal shear keys. The equation requires only the elastic analysis results of the bridge and the gap size between superstructure and shear keys.

• Structural Engineering and Mechanics
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• v.8 no.6
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• pp.531-546
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• 1999

The paper presents an experimental and theoretical study on the influence of steel fibers and longitudinal tension and compression reinforcements on immediate and long-term deflections of high-strength concrete beams of 85 MPa (12,300 psi) compressive, strength. Test results of eighteen beams subjected to sustained load for 180 days show that the deflection behavior depends on the longitudinal tension and compression reinforcement ratios and fiber content; excessive amount of compression reinforcement and fibers may have an unfavorable effect on the long-term deflections. The beams having the ACI Code's minimum longitudinal tension reinforcement showed much higher time-dependent deflection to immediate deflection ratio, when compared with that of the beams having about 50 percent of the balanced tension reinforcement. The results of theoretical analysis of tested beams and those of a parametric study show that the influence of steel fibers in increasing the moment of inertia of cracked transformed sections is most pronounced in beams having small amount of longitudinal tension reinforcement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.8
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• pp.763-770
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• 2000

In tunnel ventilation, the Purpose of ventilation control is to keep the required pollution level with minimum consumption of energy But tunnel ventilation has large disturbances caused by discharge of pollutants, traffic forces especially strong for longitudinal ventilation. Hence in this paper, the tunnel ventilation control logic applying fuzzy control theories is proposed and the simulation program of tunnel ventilation control is developed. The characteristics of longitudinal ventilation with jet fans are estimated and the effect of the proposed tunnel ventilation control is verified by the simulation program.

• Advances in nano research
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• v.13 no.2
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• pp.147-164
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• 2022

This article investigates the longitudinal vibration of a nanorod embedded in viscoelastic medium according to the nonlocal strain gradient theory. Viscoelastic medium is considered based on Kelvin-Voigt model. Governing partial differential equation is derived based on longitudinal equilibrium and analytical solution is obtained by adopting harmonic motion solution for the nanorod. Modal frequencies and corresponding damping ratios are presented to demonstrate the influences of nonlocal parameter, material length scale, elastic and damping parameters of the viscoelastic medium. It is observed that material length scale parameter is very influential on modal frequencies especially at lower values of nonlocal parameter whereas increase in length scale parameter has less effect at higher values of nonlocal parameter when the medium is purely elastic. Elastic stiffness and damping coefficient of the medium have considerable impacts on modal frequencies and damping ratios, and the highest impact of these parameters on frequency and damping ratio is seen in the first mode. Results calculated based on strain gradient theory are quite different from those calculated based on classical elasticity theory. Hence, nonlocal strain gradient theory including length scale parameter can be used to get more accurate estimations of frequency response of nanorods embedded in viscoelastic medium.