• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.105-112
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• 2002

Increases in excess pore water pressure without change of surcharge load were reported in clay underneath embankment at Berthierville and Olga sites after the end of construction. These abnormal phenomena could not be explained by classical consolidation theory. This paper presents a nonlinear viscoplastic model to interpret an increase in pore water pressure on natural clay, The proposed model can consider the combined processes of pore water pressure dissipation according to Darcy's law and pore water pressure generation due to viscoplastic strain, as well as time-dependent viscoplastic behaviour and strain rate dependency of preconsolidation pressure. The calculated results using numerical analysis are compared with measured ones under embankments built on soft clay at Berthierville and Olga in Quebec, Canada. It may be possible to explain the phenomenon of excess pore water pressure increase after the end of construction using the proposed nonlinear viscoplastic model.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.1
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• pp.1-6
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• 2002

The preparation of 0.9PMN-0.1PT ceramics by the metal alkoxide method and the effect of excess $Mg(OC_2H_5)_2$, $Pb(CH_3COO)_2{\cdot}3H_2O$ are reported. The excess$ Mg(OC_2H5)_2$ addition signficantly affects the rate of perovskite phase formation in 0.9PMN-0.1PT ceramics. The sample by addition of 5 wt% excess $Mg(OC_2H5)_2$ sintered at $1150^{\circ}C$ for 1 hr obtained perovskite single phase and showed 98% of the theoretical density. The dielectric constant of the pellets sintered at $1150^{\circ}C$ was increased by the addition of 5 wt% excess $Mg(OC_2H_5)_2$ and had a maximum value of 15000 at 1 kHz.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.28-33
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• 2018

Currently, the government has been expanding the supply of semi-low-pressure in order to solve the problems of unsupplied area of city gas and to secure the economical efficiency of small supplied area. It is mainly supplied from the central storage tank to each household by buried piping. It is necessary to provide such a shutoff valve that can block the excess flow gas due to pipeline leak or rupture when piping is damaged by other construction. For this study, System CFD code named Flownex has been used and a component corresponding to the actual EFV was developed. We compared Flownex results with experimental data to verify the accuracy of Flownex and confirmed the error rate to be around 2%. In this study, pipeline network modeling was done by selecting the LPG supply pipeline in a village and installed the component of the EFV at each junction. We selected the longest pipeline from the main pipeline and set scenarios so that the excess flow occurs by that the pipeline is ruptured before entering the household. The excess flow occurs by the pipeline rupture and the EFV is closed. At this time, we analyzed backflow effects to the other pipeline by closing EFV.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.75-87
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• 2006

A series of calibration chamber tests are performed to investigate the spatial distribution of the excess porewater pressure due to piezocone penetration into overconsolidated clays. It was observed that the excess porewater pressure increases monotonically from the piezocone surface to the outer boundary of the shear zone and then decreases logarithmically, approaching zero at the outer boundary of the plastic zone. It was also found that the size of the shear zone decreases from approximately 2.2 to 1.5 times the cone radius with increasing OCR, while the plastic radius is about 11 times the piezocone radius, regardless of the OCR. Based on the modified Cam clay model and the cylindrical cavity expansion theory, the expressions to predict the Initial porewater pressure at the piezocone were developed, considering the effects of the strain rate and stress anisotropy. The method of predicting the spatial distribution of excess porewater pressure proposed in this study was verified by comparing it with the porewater pressure measured in overconsolidated specimens in the calibration chamber.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.353-358
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• 1995

The emission characteristics of a semi-Bunsen type burner for gas boilers were studied experimentally. The experimental results reveal that nitric oxide emission increases with fuel flow rate. It is linearly proportional to total fue flow rate at a small amount of fuel up to 0.4 liters per minute. It does not change significantly within the range of fuel flow rate from 0.4 to 1.2 liters per minute per nozzle and increases at large fuel flow rate. The carbon monoxide emission reveals to be dependent upon the fuel flow rate per each nozzle and the number of fuel injection nozzles. Diameter of an injection nozzle could have an effect on the emission characteristics of this type of burners. However, there is no marked change in the nitric oxide emission if the total fuel flow rate is same with different nozzle sizes.

• The Journal of the Korean life insurance medical association
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• v.30 no.2
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• pp.12-15
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• 2011

Background: The beneficial effects of implantable cardioverter defibrillators (ICDs) in primary and secondary prevention patients are well established. However, data on potential differences between both groups in mortality are scarce. The aim of this study was to assess extra risk differences between primary and secondary prevention ICD recipients. Methods: Comparative mortality figures were calculated from a source article using mortality analysis methods. Results: Mortality ratio (MR) of primary and secondary prevention ICD recipients were 393% and 373%. Excess death rates (EDR) of both groups were 42 and 38 per 1,000. Discussion: MR and EDR were higher in primary prevention group. But, there was no significant difference.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.115-123
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• 2001

This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.669-676
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• 2000

The estimation of consolidation rate is one of the important factors in the construction on soft clayey deposits. A number of researches are carried out to predict the consolidation behavior in field, however, most of the results show the discrepancies between the prediction and observation. This paper analyzes consolidation behavior of normally consolidated clay in K/sub o/ condition with 2-dimensional drainage by use of the numerical methods. Elastic and elastic-plastic finite element analyses are compared in terms of the dissipation of excess pore pressure. These results are also compared with Terzaghi-Rendulic's equation that is implemented by finite difference method. The consolidation time calculated by using elastic model is found to be similar to the result of Terzaghi-Rendulic's equation. The consolidation predicted by MCC model takes more time than other cases. Initial increase of excess pore pressure in radial drainage can be shown, however, this phenomenon does not have a significant effect on tile final consolidation time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.56-59
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• 2000

In this study, Ferroelectric $Pb(Zr_x,Ti_{1-x})O_3$(x=0.53) thin films were fabricated by the spin-coating on the Pt/Ti/$SiO_2$/Si substrate using the PZT metal alkoxide solutions with various excess Pb contents. Etching of PZT film was performed using planar inductively coupled Ar(20)$/Cl_2/BCl_3$ plasma. The etch rate of PZT film was 2450 ${\AA}/min$ at Ar(20)$/BCl_3$(80) gas mixing ratio and substrate temperature of $80^{\circ}C$. The leakage current densities of before etching and after etching PZT thin film were $6.25\times10^{-8}A/cm^2$, $8.74\times10^{-7}A/cm^2$ with electric field of 0.07MV/em, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.7
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• pp.620-628
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• 2008

Cadmium sulphide (CdS) thin film, which is used as a window layer of heterojunction solar cell, on the glass substrate was deposited by vacuum evaporation. Effects of deposition conditions such as the source and substrate temperature on electrical and optical properties of CdS films was investigated. As the source temperature was increased, the deposition rate of CdS films was increased. In addition, the optical transmittance and the electrical resistivity of CdS films were decreased as the source temperature was increased. This results were attributed to the increase of excess Cd amount in the film. The crystal structure of CdS films exhibited the hexagonal phase with preferential orientation of the (002) plane. As the substrate temperature was increased, the crystal structure of CdS films was improved and the resistivity of the films was increased due to the decrease of excess Cd in film.