• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.458-465
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• 2000

Although Fly ash possess viable engineering properties, an overwhelming majority of the fly ash from coal combustion is still placed in storage or disposal sites. Similarly, sludges generated from various water treatment operations are predominantly subject to the fate of land disposal. To prepare sludges for land disposal typically requires time consuming dewatering schemes, which can become extremely difficult to execute dependent upon the composition of the sludge and its affinity for water. This test was undertaken to reuse of fly ash and sludge with mix. In this paper includes of geotechnical properties of fly ash and fly ash-sludge mixture and results of compaction test, unconfined test, falling head test and CBR test and it was analyzed the effect on mixing fly ash with sludge.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.4
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• pp.114-122
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• 2002

Up to now, many constitutive models for clay have been proposed and studied based on the elasto-plastic or elasto-viscoplastic theory and it has been recognized that the effect of time on the loading process is a salient feature. In the present study, cyclic behavior characteristics of clay was studied with a viscoelastic-viscoplastic constitutive model for clay based on the non-linear kinematic hardening rule. In order to examine the behavior of clay several cyclic untrained triaxial tests and also their numerical simulations were performed. As results of that, it was found that the proposed model can well describe cyclic behaviors of clay such as frequency dependent characteristics, and have the high feasibility of numerical simulation for dynamic analysis.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.785-791
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• 2004

The objective of this research is to suggest anoise prediction method for a centrifugal compressor. It is focused on the Blade Passing Frequency component which is regarded as the main part of the rotating impeller noise. Navier-Stokes solver is used to simulate the flow-field of the centrifugal compressor, and the time-dependent pressure data are calculated to perform the near-field noise prediction by using Ffowcs Williams - Hawkings formulation. Indirect Boundary Element Method is applied to consider the noise propagation effect. Pressure fluctuations of the inlet and the outlet in the centrifugal compressor impeller are presented and the sound pressure level prediction results are compared with the experimental data.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.126-130
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• 1992

Recently, fatigue problem become a critical issue in the design of prestressed concrete bridges due to the increase of traffic volumes and use of high-strength materials. Most existing studies are mainly concerned with the fatigue behavior of component materials only such as concrete, reinforcing bars, and prestressing steels and few studies exist that deals with the fatigue behavior of bridge members. An improved analytic formulation for both uncracked and cracked prestressed concrete composite section with cyclic creep effect is developed to take into account the change of neutral axis with crack propagation. The procedure also enables to investigate serviceability limit states, deflection and crack width. The present study allows more realistic analysis and design of prestressed concrete composite girder bridges under fatigue loadings.

• Geotechnical Engineering
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• v.3 no.4
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• pp.7-20
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• 1987

This study was performed to investigate the effect of time-dependent creep on the deformation analysis of multi-dimensional consolidation using the finite element method for young Sedimentary clay. It was assumed that the creep in the clay had occured during consolidation. In the analysis, the Modified cam-clay theory originated from the critical state theory was used as the constitutive equation, in which a term equivalent to the creep was supplemnted. The results of the analysis were in good agreement with the observed values in the field.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.854-859
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• 2008

This study describes the aging behavior of soils and its mechanism, which have been reported in the literatures mainly by Mitchell(1986) and Schmertmann(1991). It could be known that aging of soils has both positive and negative effects on mechanical properties of soils. In order to show aging effects on dam behavior, a parametric study was carried out based considering the presence of a weak area within clay core zone of the fill dam. From the comparison of results obtained from numerical analysis and filed investigation, age-softening phenomena occurred within core zone during about 30 years after its completion.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1061-1066
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• 2014

Time-dependent formulations of the reactive scattering theory based on the wavepacket correlation functions with the M${\phi}$ller wavepackets for the electronically nonadiabatic reactions are presented. The calculations of state-to-state reactive probabilities for the quasi-Jahn-Teller scattering model system were performed. The conical intersection (CI) effects are investigated by comparing the results of the two-surface nonadiabatic calculations and the single surface adiabatic approximation. It was found that the results of the two-surface nonadiabatic calculations show interesting features in the reaction probability due to the conical intersection. Single surface adiabatic calculations with extended Born-Oppenheimer approximation using simple wavepacket phase factor was found to be able to reproduce the CI effect semi-quantitatively, while the single surface calculations with the usual adiabatic approximation cannot describe the scattering process for the Jahn-Teller model correctly.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.8-14
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• 2001

We develop a method to analyze dynamic behavior off multi-stage gear train system. The example system consists of three shafts supported by ball bearings at the ends of them and two pairs of spur gear set. For exact analysis, the meshing tooth pair of gear set is modeled as spring and damper having time-dependent meshing stiffness and damping. The bearing is modeled as spring. The result of this analysis is compared to that of other model having mean mesh stiffness. The effect of the excitation force by the unbalance off rotor off motor is also analyzed. Finally, the change ova natural frequency of the whole system due to the change of an angle between three shafts is compared in each case, and from this analysis, the avoiding angle for design is advised.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.99-104
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• 1999

In this paper, dynamic behavior of a two stage gear train system is analyzed. This system consists of three shafts supported by ball bearing at the ends of them and two pairs of spur gear sets. For exact analysis, the meshing tooth pair of gears is modeled as spring having time-dependent meshing stiffness and damping. The result of this analysis is compared to that of analysis using other model of spring having mean mesh stiffness. The effect of the excitation force by the imbalance of a rotor of a motor on the vibration of a gear train system is also analyzed. Finally, the change of a natural frequency of the whole system due to the change of an angle between three shafts is compared in each case, and from this analysis, the avoiding angle for design is advised.

• YAKHAK HOEJI
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• v.39 no.6
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• pp.689-694
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• 1995

Sphingolipids play important roles in cell regulation and signal transduction. Recently, a sphinogomyelin cycle has been described in which activation of neutral sphingomyelinase leads to the breakdown of sphingomyelin and the generation of ceramide. Ceramide, in turn, has emerged as a candidate intracellular mediator for the action of certain cell agonists and has multiple biologic actions. Ceramide is a potent suppressor of cell growth and an inducer of apoptosis. The present studies show that exposure of IM-9 cells to ceramide resulted in internucleosomal cleavage of DNA, yielding laddered patterns of oligonucleosomal fragments characteristic of apoptosis. DNA fragmentation induced by ceramide was also confirmed by diphenylamine assay. The effect of ceramide on cell cycle progression was also studied. The addition of ceramide increase G$_{1}$ phase distribution in cell cycle. Cell cycle-related cyclin D$_{1}$ gene expression was decreased in a time-dependent manner. These results suggest that apoptosis induced by ceramide is related to cell cycle associated with the alteration of cell cycle in IM-9 cells.