• Journal of Korean Society of Steel Construction
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• v.20 no.3
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• pp.409-419
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• 2008

A co-rotational quasi-conforming formulation of four- node stress resultant shell elements using Ivanov-Ilyushin yield criteria are presented for the nonlinear analysis of plate and shell structure. The formulation of the geometrical stiffness is defined by the full definition of the Green strain tensor and it is efficient for analyzing stability problems of moderately thick plates and shells as it incorporates the bending moment and transverse shear resultant force. As a result of the explicit integration of the tangent stiffness matrix, this formulation is computationally very efficient in incremental nonlinear analysis. This formulation also integrates the elasto-plastic material behaviour using Ivanov Ilyushin yield condition with isotropic strain hardening and its asocia ted flow rules. The Ivanov Ilyushin plasticity, which avoids multi-layer integration, is computationally efficient in large-scale modeling of elasto-plastic shell structures. The numerical examples herein illustrate a satisfactory concordance with test ed and published references.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.3
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• pp.168-174
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• 2016

A conductive oxide-based sapphire glass indium tin oxide/metal electrode and the optical coating, through patterning process was studied in excellent optical properties and integrated touch panel has a high strength. Indium tin oxide conductive oxides of the sapphire glass to 0.3 A at DC magnetron sputtering method of 10 min, gas flow Ar 10 Sccm Ar, $O_2$ 1.0 Sccm the formation conditions of the thin film after annealing at $550^{\circ}C$ for 30min was achieved through a 86% transmittance. In addition, the coating 130 nm hollow silica sol-gel was to improve the optical transmittance of the indium tin oxide to 91%. For the measurement by the modeling hollow silica sol by Macleod simulation and calculated the average values of silica part to the presence or absence in analogy to actual. Refractive index value and the actual value of the material on the simulation the transmittance difference is it does not completely match the air region similar to the actual value (transmission) could be confirmed that the measurement is set to a value of between 5 nm and 10 nm.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.196-205
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• 2008

Variability in vertical ozone and meteorological profiles was measured by 2Z electrochemical concentration cells (ECC) ozonesonde at Bangyi in Seoul ($37.52^{\circ}N$, $127.13^{\circ}E$) during June $6{\sim}9$, 2003 in odor to identify the vertical distribution of ozone and its relationship with the lower-atmospheric structure resulted in the high ozone concentrations near the surface. The eight profiles obtained in the early morning and the late afternoon during the study period clearly showed that the substantial change of ozone concentrations in lower atmosphere(${\sim}5\;km$), indicating that it is tightly coupled to the variation of the planetary boundary layer (PBL) structure as well as the background synoptic flow. All profiles observed early in the morning showed very low ozone concentrations near the surface with strong vertical gradients in the nocturnal stable boundary layer due to the photochemical ozone loss caused by surface NO titration under very weak vertical mixing. On the other hand, relatively uniform ozone profiles in the developed mixing layer and the ozone peaks in the upper PBL, were observed in the late afternoon. It was noted that a significant increase in ozone concentrations in the lower atmosphere occurred with the corresponding decrease of the mixing height in the late afternoon on June 8. Ozone in upper layer did not vertically vary much compared to that in PBL but changed significantly on June 6 that was closely associated with the variation of synoptic flows. Interestingly, heavily polluted ozone layers aloft (a maximum value of 115 ppb around 2 km) were formed early in the morning on 6 through 7 June under dominant westerly synoptic flows. This indicates the effects of the transport of pollutants on regional scale and consequently can give a rise to increase the surface ozone concentration by downward mixing processes enhanced in the afternoon.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.301-311
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• 2004

This study is suggested a new dielectric tracer test method to understand geological structure of porous media and groundwater flow to use the dielectric constant which is one of electrical special quality of various geological materials. To measure their parameters, tracer material is made an ethanol mixing liquid(EML) having a same specific gravity of water. Also, soil materials are prepared a dielectric tracer test using the FDR system that could measure dielectric constant for saturated standard sand and river sand layers which have different initial porosity. To compare with their results, we discussed with the concentration variation of saline water having a saline concentration $3\%$ which is general tracer material by using the electro multi-meter system in the laboratory or field test. In two tracer experiment results, EML tracer test could confirm definitely EML concentration variation from each saturated soil layer as standard and river sands. However, tracer test of saline water $3\%$ concentration could not confirm permeating movement of water by degree of salinity change because these are settled at lower part column in a whole column area continuously. These causes are that specific gravity of saline water is heavier than water. That is, it could know that deposition of saline water is composed of lower part of soil column continuously independently of the direction of water into saturated soil material.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.5
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• pp.587-609
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• 2019

Short-and long-term stabilities of bentonite, favored material as buffer in geological repositories for high-level waste were reviewed in this paper in addition to alternative design concepts of buffer to mitigate the thermal load from decay heat of SF (Spent Fuel) and further increase the disposal efficiency. It is generally reported that the irreversible changes in structure, hydraulic behavior, and swelling capacity are produced due to temperature increase and vapor flow between $150{\sim}250^{\circ}C$. Provided that the maximum temperature of bentonite is less than $150^{\circ}C$, however, the effects of temperature on the material, structural, and mineralogical stability seems to be minor. The maximum temperature in disposal system will constrain and determine the amount of waste to be disposed per unit area and be regarded as an important design parameter influencing the availability of disposal site. Thus, it is necessary to identify the effects of high temperature on the performance of buffer and allow for the thermal constraint greater than $100^{\circ}C$. In addition, the development of high-performance EBS (Engineered Barrier System) such as composite bentonite buffer mixed with graphite or silica and multi-layered buffer (i.e., highly thermal-conductive layer or insulating layer) should be taken into account to enhance the disposal efficiency in parallel with the development of multilayer repository. This will contribute to increase of reliability and securing the acceptance of the people with regard to a high-level waste disposal.