• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.337-343
• /
• 2021

In this work, self-absorption correction factor related to the variation of the composition and the density of soil samples were evaluated using the p-type HPGe detector. The validated MCNP5 simulation model of this detector was used to evaluate its Full Energy Peak Efficiency (FEPE) under the variation of the composition and the density of the analysed samples. The results indicates that FEPE calculation of low gamma ray is affected by the composition and the density of soil samples. The self-absorption correction factors for different gamma-ray energies which was fitted as a function of FEPEs via density and energy and fitting parameters as polynomial function for the logarithm neper of gamma ray energy help to calculate quickly the detection efficiency of detector. Factor Analysis for the influence of the element composition in analysed samples on the FEPE indicates the FEPE distribution changes from non-metal to metal groups when the gamma ray energy increases from 92 keV to 238 keV. At energies above 238 keV, the FEPE primarily depends only on the metal elements and is significantly affected by aluminium and silicon composition in soil samples.

• International Journal of Safety
• /
• v.2 no.1
• /
• pp.1-6
• /
• 2003

In this paper, several different fracture criteria using the Eftis and Subramanian's stress solutions [1] are compared with the printed experimental results under different loading conditions. The analytical results of using the solution with non-singular term show better than without non-singular in comparison with the experimental data. And maximum tangential stress criterion (MTS) and maximum tangential strain energy density criterion (MTSE) can get useful results for several loading conditions.

• The Pure and Applied Mathematics
• /
• v.18 no.1
• /
• pp.79-86
• /
• 2011

Suppose that (M,g) is a complete and noncompact Riemannian mani-fold with Ricci curvature bounded below by $-K{\leq}0$ and (N, $\bar{g}$) is a complete Riemannian manifold with nonpositive sectional curvature. Let u : $M{\times}[0,{\infty}){\rightarrow}N$ be the solution of a heat equation for harmonic map with a bounded image. We estimate the energy density of u.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.5
• /
• pp.499-502
• /
• 2001

Unexpectedly, the brightest row was known to represents the lowest lying Te atoms in the STM image of NbTe2. Projected density of states and crystal orbital overlap population show that the 5pz orbital of the lowest lying Te(2) atom doe s not interact with the 4d orbital of Nb strongly so that the 5pz band remains in the vicinity of the Fermi energy. Consequently the lowest lying Te(2) atoms contribute higher electron density near the Fermi energy which in turn exhibits brightest image in the STM experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.1
• /
• pp.60-65
• /
• 2000

The structural and electrical characteristics of PLZT thin films fabricated onto Pt/Ti/SiO\ulcorner/Si substrates by a pulsed laser deposition were investigated to develop the high dielectric thin films were fabricated with different energy density by pulsed laser deposition. This PLZT thin films of 5000 thickness were crystallized at 600 $^{\circ}C$, 200 mTorr O\ulcorner pressure for 2 J/$\textrm{cm}^2$ laser energy density, the arain structure was transformed from planar to columnar grain. It was clearly noted from the SEM observations that oxygen pressured laser powers affect microstructures of the PLZT thin films. 14/50/50 PLZT this film showed a maximum dielectric constant value of $\varepsilon$\ulcorner=1289.9. P-E hysteresis loop of 14/50/50 PLZT thin film was flim ferro-electric. Leakage current density of 14/50/50 PLZT thin film was 10\ulcorner A/$\textrm{cm}^2$.

• Journal of The Korean Astronomical Society
• /
• v.19 no.1
• /
• pp.33-49
• /
• 1986

Radial distribution of internal density has been determined for thirteen subclouds in the three giant molecular cloud complexes accompanying Mon OB1, Mon OB2 and CMa OB1 associations, We modeled their radial density structures with the density distribution of isothermal gas spheres. Most of the subclouds, nine out of the thirteen, are well described by isothermal spheres of single component; while the rest four require an additional component. Total mass and potential energy of each subcloud are also derived from the radial density structure; thermal energy and internal velocity dispersion required for sustaining the density structure are deduced from the isothermal gas model. Our derived masses of the clouds are comparable to the values determined by Blitz (1978) under LTE assumption. This agreement suggests that the correction factor for non-LTE effect on mass-estimate is not far from unity. The ratio of the gravitational potential energy to the kinetic energy of thermal motion is as large as 250; hence the thermal motion alone cannot support these clouds against the gravity. Being supported by turbulence motion with velocities of six to seven times the thermal velocity, the clouds of one-component type seem to be in equilibrium with the gravity; while the clouds of two-component type are likely to be in the stage of gravitational collapse.

• Journal of the Korean Society of Safety
• /
• v.23 no.6
• /
• pp.21-27
• /
• 2008

Polypropylene(PP) foams are widely used as protective materials such as automotive bumper and safety helmet, but whose dynamic behaviour are not well defined. In this paper, the compression tests by Split Hopkinson Pressure Bar were conducted to obtain the stress-strain curve and to investigate the effect of density on the absorption of impact energy in the PP foams. Three kinds of foams were chosen depending upon the density. The result of the experiment has revealed that the stiffness of the low-density PP foam is remarkably increased at high strain rate compared with that of the high-density PP foam. And it is also shown that the absorption of impact energy are greatly influenced by the density of PP foam. These results are expected to be utilized for the development of a protective structure with polymer foams.

• Journal of Environmental Science International
• /
• v.6 no.4
• /
• pp.313-322
• /
• 1997

In order to study the seasonal variation of kinetic and potential energy of residual flow field In Suyoung Bay of Korea, we calculated Its energy budget and compared It with the tidal energy there. The potential energy shows the large value In winter and spring and the small one In summer and early autumn when the density stratification Is developed. The kinetic energy of residual flow varies seasonally and the seasonally averaged kinetic energy of residual flow per unit area is 6.4$\times$$10^{-4}ergs s^{-1}cm^{-}2$. It Is mainly governed by the density-driven current with the exception of that In November when the kinetic energy of tide-induced residual current is larger than those of density-driven current and wind-driven current. An averaged traction of the kinetic energy of tide-Induced residual current, wind-driven current and density-driven current, which are the major components of residual flow, is 29.1%, 3.4%, 67.5%, respectively, to the kinetic energy of residual flow, The fraction of kinetic energy of residual flow, potential energy and tidal energy per unit area is 1.0 : 6.7$\times$$10^3$: 8.2$\times$$10^4$ respectively.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.10 no.6
• /
• pp.381-390
• /
• 2015

The efficient design of a transport protocol contributes to energy conservation as well as performance improvement in wireless sensor networks (WSNs). In this paper, a node-density-aware transport protocol (NDTP) for intra-cluster transmissions in WSNs for monitoring physical attributes is proposed, which takes node density into account to mitigate congestion in intra-cluster transmissions. In the proposed NDTP, the maximum active time and queue length of cluster heads are restricted to reduce energy consumption. This is mainly because cluster heads do more works and consume more energy than normal sensor nodes. According to the performance evaluation results, the proposed NDTP outperforms the conventional protocol remarkably in terms of network lifetime, congestion frequency, and packet error rate.

• Journal of the Korean Electrochemical Society
• /
• v.9 no.4
• /
• pp.151-157
• /
• 2006

A two-dimensional numerical model to study the performance of anode-supported flat-tube solid oxide fuel cell (SOFC) far the cross section of the cell in the flow direction of the fuel and air flows is developed. In this model a mass and charge balance, Maxwell-Stefan equation as well as the momentum equation by using, Darcy's law are applied in differential form. The finite element method using FEMLAB commercial software is used for meshing, discritization and solving the system of coupled differential equations. The current density distribution and fuel consumption as well as water production are analyzed. Experimental data is used to verify a predicted voltage-current density and power density versus current density to judge on the model accuracy.