• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.429-434
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• 2016

Here, we introduce a means of utilizing waste oyster shells which were obtained from temporary storage near coastal workplaces as $CO_2$ adsorbents. The calcined CaO can be easily dissociated to $Ca^{2+}$ cation and $CO_3{^{2-}}$ anion by hydrolysis and gas-liquid carbonation reaction and converted to precipitated calcium carbonate (PCC) in algae-containing water. The calcium hydroxide and carbonation combination in algae-containing water significantly contributed to improving water quality which is very dependent on the addition amount of calcined powders.

• Environmental Analysis Health and Toxicology
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• v.4 no.3_4
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• pp.29-59
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• 1989

For the purpose of electrolytic treatment of wastewater containing various heavy metals, the BPBE Cell of batch and continuous type was considered and experimented. Some results from this study were summarized as follows: 1. When the artificial wastewater containing 500 mg/l of the concentration of various heavy metallic ion was electrolyzed in BPBE Cell of batch type, the removal efficicency was over 95% in cadmiun (II), lead (II), chromium (Ⅵ) and over 85% in copper (II), chromium (III). 2, As granular activated carbon packed in BPBE Cell, coconut shell was superior to lignite and the removal efficiency was the highest when the activated carbon was 4/6 mesh, the voltage was 20V. 3. When the heavy metallic ion in wastewater was electrolyzed in BPBE Cell of continuous type, about 1,000mg of heavy metal per 1kg of coconut sell could be removed. 4. The treatment method of heavy metallic ion in wastewater by BPBE Cell cost less than in the former chemical treatment method and the coconut shell packed in BPBE Cell could be regenerated by chemical method.

• Steel and Composite Structures
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• v.35 no.6
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• pp.765-777
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• 2020

In the context of classic conical shell formulation, nonlinear forced vibration analysis of truncated conical shells and annular plates made of multi-scale epoxy/CNT/fiberglass composites has been presented. The composite material is reinforced by carbon nanotube (CNT) and also fiberglass for which the material properties are defined according to a 3D Mori-Tanaka micromechanical scheme. By utilizing the Jacobi elliptic functions, the frequency-deflection curves of truncated conical shells and annular plates related to their forced vibrations have been derived. The main focus is to study the influences of CNT amount, fiberglass volume, open angle, fiber angle, truncated distance and force magnitude on forced vibrational behaviors of multi-scale truncated conical shells and annular plates.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2631-2636
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• 2008

The most components and piping of the secondary side of domestic nuclear power plants were manufactured carbon-steel and low-alloy steel. Flow accelerated corrosion leads to wall thinning (metal loss) of carbon steel components and piping exposed to the flowing water or wet steam of high temperature, pressure, and velocity. The feedwater heaters of many nuclear power plants have recently experienced sever wall thinning damage, which increases as operating time progress. Several nuclear power plants in Korea have also experienced wall thinning damage in the shell wall around the impingement baffle. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the experimental results based on down-scaled experimental facility. The experiments were performed based on several types of impingement baffle plates which are installed in low pressure feedwater heater.

• Advances in concrete construction
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• v.13 no.6
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• pp.451-459
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• 2022

In present study, the nonlocal Flügge shell model based is utilized to investigate the vibration characteristics of armchair and chiral single-walled carbon nanotubes with impact of small-scale effect subjected to two boundary supports. The wave propagation approach is employed to determine eigen frequencies for armchair and chiral tubes. The fundamental frequencies scrutinized with assorted aspect ratios by varying the bending rigidity. The raised in value of nonlocal parameter reduces the corresponding fundamental frequency. It is investigated with higher aspect ratio, the boundary conditions have a momentous influence on vibration of CNT. It is concluded that frequencies would increase by increasing of the bending rigidity. Solutions of the frequency equation have determined by writing in MATLAB coding.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.36-41
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• 1998

The objective of this study is to investigate effects of prebuckling on the buckling of laminated composite cylindrical shells. axial compression is considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. This study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.03a
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• pp.112-116
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• 1998

The objective of this study is to investigate effects of prebuckling on the buckling of laminated composite cylindrical shells. Axial compression is considered for laminated composite cylindrical shells with length to radius ratios. The shell walls are made of a laminate with several symmetric ply orientations. This study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when membrane prebuckling displacements are considered.

• Journal of Wetlands Research
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• v.25 no.1
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• pp.1-13
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• 2023

Coastal shellfish in the shallow aquaculture waters form carbon contained shells as they grow. The existing researches showed that carbon flux can be improved, if the shells are re-treated by the carbon stored methods. In the present study, firstly, the mechanism and the quantitative flux of carbon dioxide in the shellfish individual have been analyzed. The re-treated methods of the useful by-product in the shellfish aquaculture, shells, have been reviewed. Finally, the potential effects to reduce the greenhouse gas has been suggested, if the shells can be properly re-treated.

• Journal of the korean society of oceanography
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• v.32 no.2
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• pp.63-68
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• 1997

Stable isotope profiles with fine-scale resolution were constructed from the fossil mollusk shells, Mercernaria mercernaria, obtained from the late Pleistocene transgressive deposits of Gomez Pit, Virginia, USA. Incremental sampling were made along the axis of maximum growth to provide high-resolution ${\delta}^{18}$O and ${\delta}^{13}$C records. The ${\delta}^{18}$O shell profiles exhibit a series of pronounced cycles in the overall amplitude, corresponding to strong seasonal variations in temperature, which is apparently positive environmental variable. Contrasts between the patterns of ${\delta}^{18}$O and ${\delta}^{13}$C profiles reflect the relationship influencing the seasonal carbon cycling in the shallow marine environment. Positive anomalies of the ${\delta}^{13}$C values during the summer were observed to be out of phase with the ${\delta}^{18}$O profile. Such relatively heavier carbon source may be alternated due to seasonal methanogenesis during the summer. A hypothesized methane-based system may be operated in the shallow and marginal marine environment, resulting in a ${\delta}^{13}$C enriched bicarbonate pool, in which the heavier isotope seems to be incorporated to the shell carbonate.

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.565-578
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• 2018

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.