• Tunnel and Underground Space
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• v.6 no.1
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• pp.30-38
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• 1996

A two dimensional analysis program for groundwater flow in fractured network was developed to analyze the influence of discontinuity characteristics on groundwater flow. This program involves the generation of discontinuities and also connectivity analysis. The discontinuities were generated by the probabilistic density function(P.D.F.) reflecting the characteristics of discontinuities. And the fracture network model was completed through the connectivity analysis. This program also involves the analysis of groundwater flow through the discontinuity network. The result of numerical experiment shows that the equivalent hydraulic conductivity increased and became closer to isotropic as the density and trace length increased. And hydraulic head decreased along the fracture zone because of much water-flow. The grouting increased the groundwater head around cavern. An analysis of groundwater flow through discontinuity network was performed around underground oil storage cavern which is now under construction. The probabilistic density functions(P.D.F) were obtained from the investigation of the discontinuity trace map. When the anisotropic hydraulic conductivity is used, the flow rate into the cavern was below the acceptable value to maintain the hydraulic containment. But when the isotropic hydraulic conductivity is used, the flow rate was above the acceptable value.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.278-284
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• 2009

The global force and interaction body force density were evaluated in permanent magnets by using the virtual air-gap scheme incorporating the finite-element method. Until now, the virtual air-gap concept has been successfully applied to calculate a contact force and a body force density in soft magnetic materials. These force calculating methods have been called as generalized methods such as the generalized magnetic charge force density method, the generalized magnetizing current force density method, and the generalized Kelvin force density method. For permanent magnets, however, there have been few research works on a contact force and a force density field. Unlike the conventional force calculating methods resulting in surface force densities, the generalized methods are novel methods of evaluating body force density. These generalized methods yield the actual total force, but their distributions have an irregularity, which seems to be random distributions of body force density. Inside permanent magnets, however, a smooth pattern was obtained in the interaction body force density, which represents the interacting force field among magnetic materials. To evaluate the interaction body force density, the intrinsic force density should be withdrawn from the total force density. Several analysis models with permanent magnets were tested to verify the proposed methods evaluating the interaction body force density and the contact force, in which the permanent magnet contacts with a soft magnetic material.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1117-1121
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• 2010

Several isotropic compression-expansion tests and a series of drained conventional traxial tests with various confining pressures for relative density of Beakma river sand 25%, 50%, 80% and 100% selecting Lade's Single Work-Hardening constitutive model. This examination materials use regression analysis as a basis, depending on the relative density of soil parameters change statement attributes. Yield fuction represent the soil parameters h and $\alpha$ is not affected by the changes in the relative density. $\eta_1$ could be replaced by fomula. And Numerical analysis results predicted very good and could confirm that.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1121-1124
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• 2001

In this study, we verify th effects of pattern density on interlayer dielectric chemical mechanical polishing process based on the analysis of Preston's equation and confirm this analysis by several experiments. Appropriate modeling equation, transformed form Preston's equations used in glass polishing, will be suggested and described the effects of this modeling during pattern wafer ILD CMP. Results indicate that the modeling is well agreed to middle density structure of the die in pattern wafer, but has some error in low and high density structure of the die. Actually, the die used in Fab, was designed to have a appropriate density, therefore this modeling will be suitable for estimating the results of ILD CMP.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1201-1206
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• 2004

This paper deals with the numerical analysis of natural convection flow induced by the density inversion effect of water inside horizontal pipe. The numerical method is based on SIMPLE/PWIM in general coordinate for its wide applicabilities. The numerical tool was validated through the comparison with the previous results concerning the density inversion effect of water It is shown that the developed numerical tool could predict the flow pattern and the heat transfer phenomena qualitatively And it is also found that the density inversion effect of water has significant effects on the flow pattern.

• Journal of Magnetics
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• v.15 no.4
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• pp.190-193
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• 2010

The design of joints in a transformer core significantly affects the transformer's efficiency. Air gaps cause variations in the flux distribution at the joints of the laminations, which depend on the geometry. Two similar samples consisting of electrical steel strips and amorphous ribbons were made. The spatial flux distributions were determined using an array of search coils for each sample. 2D models of these samples were created and examined by finite element analysis. The magnetic flux distribution for each lamination in the samples was computed. The results show that the flux density in amorphous ribbons above and below the air gap starts to approach saturation at lower flux density levels than for electrical steel. The flux density measured using the search coil under the air gap is increased in amorphous ribbons and decreased in the electrical steel with increasing frequency.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.912-920
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• 2006

The purpose of this study is to present the design standard for load density in subway station. From the data of electric equipment capacity and electric power consumption for 43 subway stations, current levels of the load density and excess capacity factor were surveyed and analyzed, In addition mean value, standard deviation, maximum value, median value and correlation coefficient were evaluated through excel program. Also it was carried out the regression analysis. The estimation method of load density and design criterion were studied. As a result, load density in this thesis have been proposed : 51.3 $[VA/m^2]$ on the general power load can be a standard value for subway station.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.2
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• pp.29-35
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• 1992

The distribution of magnetic flux density of electro-magnetic chucks may clarify the clamping characteristics which are strongly related to the machining efficiency and machining accuracy in a surface grinder. Therefore the distribution of the normal and the tangential components of magnetic flux density has been analyzed theoretically. It appears that the normal and the tangential components of magnetic flux density increase as the ratio of the separator width to the pitch e/p decreases. The results seem to increase the uniformity and stability of normal component of magnetic flux density for the decreased e/p.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.537-540
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• 2003

In this paper, we evaluated error correction performance and recording density of an optical disc system. The performance of Low-Density Parity Check code (LDPC) is compared to the HD-DVD (BD) ECC. The recording density of optical disc can be increased by reducing the redundancy of the user data. Moreover, since the correction capability of LDPC with decreased redundancy is better than that of BD, the recording density can also be increased by reducing the mark length of the data on the disc surface.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.8
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• pp.365-370
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• 2005

Microwave diagnostics have been widely utilized to measure the important parameters of high temperature and high density plasmas. Reflectometry is known as a promising microwave diagnostic which has a number of merits to measure electron density profiles. In the KSTAR device, X-mode FM reflectometry is planned to measure the plasma density profiles. FM reflectometry is required to extract phase information on raw mixer IF signals, thereby obtaining time-of-flight of reflectometry signals. It is known that the data analysis method is crucial to determine the performance of FM reflectometry In fact, there are several analysis programs which have been utilized in various FM systems. Since each program was developed for a specific device, however, it is difficult to directly apply it to a different reactor like the KSTAR device. It is necessary, therefore, to develop a data analysis program for the KSTAR FM reflectometry. In this paper, complex digital demodulation (CDM) and wavelet transformation are examined in terms of the performance of density profile reconstruction. For the comparison of both methods, FM reflectometry signals are generated on the basis of assumed profiles and the interaction of the X-mode wave and the plasma. In order to see how well both methods work under various conditions, three types of profiles are assumed and noise effects are included. As a result, both methods work well under the condition of gentle density gradient and small noise level. As density gradient becomes steeper and noise level gets higher. the reconstruction performance of wavelet is better than that of CDM.