• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.617-626
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• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.522-526
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• 1992

Carbonation process of an aqueous solution of $Ca(OH)_2$ with $CO_2$ gas at $10^{\circ}C$ has been studied to investigate the formation and transformation processes of amorphous calcium carbonate. It was suggested that the amorphous calcium carbonate consisting of spherical particles with the diameter in the range of $0.02{\sim}0.05{\mu}m$ be a non-stoichiometric $CaCO_3$ phase containing small amounts of $H_2O$ and small incorporations of $HCO^-_3$. Amorphous $CaCO_3$ is unstable in the aqueous solution and converts to calcite, and its morphology depends on the carbonate species present in the slurry such that with [$CO_3^{2-}$] prevailing, chain-like calcite composed of ultrafine colloidal particles and with [$HCO^-_3$] prevailing, rhombohedral particles of calcite are formed respectively. Therefore, morphological control of calcium carbonate crystals could be expected by the adequate controls of transformation process of the amorphous calcium carbonate.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.338-344
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• 2008

The improvement of energy conservation is mandatory to decrease consumption of fossil fuels and to minimize negative impacts on the environment which originates from large cooling and heating demand. The absorption heat pump technology has a large potential for energy-saving in this respect. Absorption heat pump is a means to upgrade waste heat without the addition of extra thermal energy. The higher performance of absorber is of great importance for absorption heat pump cycle. In this study, in order to improve the performance of absorber, the absorber of tangential feed of a liquid phase with spiral tube has been investigated using methanol-glycerine as a working fluid. The spiral tube and tangential feeding generate the turbulence into the liquid flow while increasing the mass and heat transfer coefficients. The simultaneous heat and mass transfer were found to take place in a liquid turbulent film in the absorber with the spiral tube during the process of gas absorption. By calculating mass and heat transfer coefficients by measurement of the concentration and the temperature of each position in the absorber, the entrance was found to be more effective in enhancing mass and heat transfer.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.3
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• pp.173-179
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• 2004

In this study, the influence of heat treatment and Ca contents on the electrochemical behavior was investigated. Mg-Ca alloys, i.e., Mg-0.22wt%Ca, Mg-0.56wt%Ca, Mg-1.31wt%Ca are prepared by ingot metallurgy. As-cast Mg-Ca alloys exhibited better electrochemical properties than pure Mg. Especially, Mg-0.22wt%Ca alloy improves its anode efficiency up to 62% and lowers the OCP up to -1.72VSCE. Microstructure and XRD patterns of Mg-Ca alloys show that additive Ca element is mainly solid-solutioned. While, the others show the microstructure and XRD pattern with large $Mg_2Ca$ at grain boundary. To assess the effect of heat treatment on the as-cast Mg-alloy, the specimens were heat treated at $200^{\circ}C$ for 2 hours under $CO_2$ gas atmosphere. Although corrosion properties of Mg-Ca alloys are somewhat deteriorated by heat treatment at $200^{\circ}C$ Mg-0.22wt%Ca alloy with uniformly distributed nano-sized $Mg_2Ca$ phase in ${\alpha}$-Mg matrix show still better corrosion properties than pure Mg specimen.

• Fire Science and Engineering
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• v.32 no.3
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• pp.76-87
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• 2018

This study describes the damage effects modeling for a quantitative prediction about the hazardous distances from pressurized chlorine saturated liquid tank, which has two-phase leakage. The heavy gas, chlorine is an accidental substance that is used as a raw material and intermediate in chemical plants. Based on the evaluation method for damage prediction and accident effects assessment models, the operating conditions were set as the standard conditions to reveal the optimal variables on an accident due to the leakage of a liquid chlorine storage vessel. A model of the atmospheric diffusion model, ALOHA (V5.4.4) developed by USEPA and NOAA, which is used for a risk assessment of Off-site Risk Assessment (ORA), was used. The Yeosu National Industrial Complex is designated as a model site, which manufactures and handles large quantities of chemical substances. Weather-related variables and process variables for each scenario need to be modelled to derive the characteristics of leakage accidents. The estimated levels of concern (LOC) were calculated based on the Gaussian diffusion model. As a result of ALOHA modeling, the hazardous distance due to chlorine diffusion increased with increasing air temperature and the wind speed decreased and the atmospheric stability was stabilized.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.544-549
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• 2017

This paper aims to examine the effect of rotational fluid motion about the efficiency of the gas - liquid ejector, which is a core unit in a ship equilibrium water treatment system. The ejector is a device for injecting ozone into ship equilibrium by the negative pressure generated by exchange of momentum between water and ozone. The existing ejector ejects the driving fluid with a simple form. In this paper, however, a rotation induction device is applied to the driving nozzle so that the driving fluid can be rotated and injected. To investigate the flow characteristics by the rotational movement of the driving fluid, CFD was used. The pressure and flow rate of the driving fluid, the negative pressure and suction flow rate of the suction fluid in the suction part, and the discharge pressure were predicted. On the basis of the results, the efficiency of the ejector using the rotation induction system was 22.25%, which was about 1.7% better than that of the existing ejector. Finally, to verify the feasibility of the CFD, an experiment was conducted on the ejector using the rotation induction device and the results were similar to those of the CFD.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.316-322
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• 2014

With increase in demand for higher operating temperatures of gas turbines, extensive research efforts have been carried out to enhance the performance of thermal barrier coatings (TBCs) in the field of coating processing as well as materials. In this study, thermal barrier coatings in lanthanum/gadolinium zirconate system, which is one of the most promising candidates for replacing yttira-stabilized zirconia (YSZ) in thermal barrier coating applications, are fabricated via suspension plasma spray. Dense, $300{\sim}400{\mu}m$ thick coatings of fluoritephase zirconate with modest amount of segmented microstructures are obtained by using suspension plasma spray with suspensions of planetary-milled mixture between lanthanum and/or gadolinium oxide and nano zirconia. These coatings exhibit thermal conductivities of 1.6 ~ 1.7 W/mK at $1000^{\circ}C$, which is relatively lower than that of YSZ.

• Journal of the Korean Applied Science and Technology
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• v.34 no.4
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• pp.892-898
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• 2017

In this study, the basic properties of recoverable gaseous and solid materials were investigated from heavy oil contained in the resources. The basic characteristics of pyrolysis reaction for the conversion of bituminous oil to pyrolysis various temperature were investigated. The characteristics of gas and solid phase byproducts were also investigated with a laboratory scale fixed bed reactor according to various reaction temperature. As a result, it was confirmed that the oil yield was about 17% at $550^{\circ}C$ and $CH_4$, $CaCO_3$ and CaO could be recovered as by-products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.5
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• pp.917-920
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• 2004

The migration potential of volatile organic solvents widely employed in the printing process of food packaging was investigated by using a closed experimental system, which contained a food sample and a paper sheet spiked with the contaminant solvents. The studied organic compounds included toluene and p,m,o-xylene which are relatively highly volatile. Typical food samples of caramel, beef jerky and butter were selected based on their chemical composition and were assigned to the migration system at 10, 25 and 4$0^{\circ}C$. The equilibrated migration level was very high with almost complete transfer in the butter with high fat, while caramel of high carbohydrate content and beef jerky of high protein showed migration degree of 37∼56% and 37∼77%, respectively. Temperature did significantly influence the migration on beef jerky with higher level at higher temperature. There was no difference in the migration level among the solvents.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.510-515
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• 1994

Yttria-stabilized zirconia(YSZ) films were prepared onto p-type (100) silicon wafer by a plasma-enhanced metallorganic chemical vapor deposition(PE MO CVD) processing involving the application of vapor mixture of tri(2.2.6.6-tetramethyl-3, 5-heptanate) yttrium$[Y(DPM)_3]$, zirconiumtriflouracethyla cetonate$(Zr(tfacac)_4$ and oxygen gas. The x-ray diffraction(XRD) and fourier transform infrared spectra(FT1R) results showed that the deposited YSZ films had a single cubic phase. $Y_2O_3$ content of YSZ film was analyzed by PIXE(partic1e induced x-ray emission). The experimental results by PIXE revealed that 12.lmol%, 20.4mol% and 31.6mol% $Y_2O_3$ could be obtained as the $Y(DPM)_3$ bubbling temperature varied at $160^{\circ}C, 165^{\circ}C$ and $170^{\circ}C$ respectively. The increase of $Y(DPM)_3$ bubbling temperature caused shifting flat band voltage to have a negative value.