• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.608-613
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• 2003

In this paper, the effect of interconnected boundary between journal and thrust bearings on the performance of self-acting air-lubricated bearings is investigated. When journal and thrust bearings have common boundary, conventional boundary condition which assumes that the boundary pressure is equal to atmosphere is no more valid. Instead, new boundary condition by mass conservation at interconnected boundary is needed. To do this, a duct model satisfying mass conservation at interconnected boundary is developed. Using this model, pressure distribution at interconnected boundary is numerically analyzed with changing the volume of interconnecting part. As a result, it is shown that load capacity of thrust bearing can be greatly increased when journal and thrust have a common boundary.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.2
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• pp.180-192
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• 1998

Enthalpy transport in a pulse tube was investigated by two-dimensional analysis of mass, momentum and energy equations assuming that the axial temperature gradient in the pulse tube is constant. Time-averaged second-order conservation equations of mass, momentum and energy were used to show the existence of steady mass streaming and enthalpy streaming. Effects of axial temperature gradient, velocity amplitude ratio and heat transfer between the gas and the wall on the steady mass streaming and enthalpy streaming were shown. Enthalpy loss due to the steady mass streaming is zero for basic and orifice pulse tube refrigerators, but it is proportional to the axial temperature gradient and steady mass flow rate through a pulse tube for double inlet pulse tube refrigerators.

• International Journal of Air-Conditioning and Refrigeration
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• v.7
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• pp.33-44
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• 1999

Enthalpy transport in a pulse tube was investigated by two-dimensional analysis of mass, momentum and energy equations assuming that the axial temperature gradient in the pulse tube was constant. The time-averaged second-order conservation equations of mass, momentum and energy were used to show the existence of steady mass and enthalpy streaming. Effects of the axial temperature gradient, velocity amplitude ratio, and heat transfer between the gas and the tube wall On the steady mass and enthalpy streaming were shown. Enthalpy loss due to the steady mass streaming is zero for basic and orifice pulse tube refrigerators, but it is proportional to the axial temperature gradient and steady mass flow rate through a pulse tube for double inlet pulse tube refrigerators.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.102-110
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• 2011

For decreasing of the casualties and designing of the smoke control systems in the ultra high-rise building, the programs for analysis of smoke control were developed for prediction of smoke spread and distributions of pressure and temperature in building fire situation. In this study, coupling algorithm between mass and enthalpy conservations was modified for improving the applicability of the CAU_ESCAP which program can consider the energy transfer. The fire situation in ultra high-rise building was applied by using the modified CAU_ESCAP. Results of pressure difference predicted by modified CAU_ESCAP are higher than results of ASCOS as stack effect is generated due to the increasing of stairway temperature. Moreover, theoretically, the result of the neutral plane is more accurate than the result of ASCOS, in fire situation of ultra high-rise building.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.729-735
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• 2005

This paper has dealt with the characteristics of mass and heat transfer of vertical flat plate with free convection. The theory of similarity transformations applied to the momentum and energy equations for free convection. To derive the similarity equation of mass transfer. the equation for conservation of species was added to the continuity. momentum and energy equations. The momentum, energy and species equations set numerically to obtain the velocity, temperature and mass fraction of species as dimensionless. For cases where momentum transport dominates, the thermal boundary layers are shorter than the momentum boundary layer. The relationships between momentum, energy and species were clarified from this study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.5
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• pp.668-676
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• 2000

A two-dimensional model for pulse tubes with tapered cross-section was proposed. Net enthalpy flow and steady mass streaming were investigated by two-dimensional analysis of mass, momentum and energy equations of the gas as well as energy conservation of the tube wall. Steady mass flux profiles show good agreement with the previous approximate solution. It was shown that steady mass streaming can be reduced by tapering a pulse tube and by increasing the length of a pulse tube. Effects of the velocity phase angle and frequency on steady mass streaming were shown.

• Journal of the Korean earth science society
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• v.35 no.3
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• pp.192-202
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• 2014

The purpose of this study was to investigate high school students' conception of conservation of mass through the scenario of carbon emission in terms of carbon cycle. Seventy six high school students of 11th grade were participated in this study. Participants were provided with two scenarios that showed a gradual increase and decrease of atmospheric $CO_2$ amount from the level recorded in 2013 up to 450 ppm and to 340 ppm by 2110, which is the changes of around 15%. We asked participants to explain the reason after having them draw the emissions trajectory of $CO_2$ according to scenario. Most participants thought that carbon emission would continue to increase despite the two scenarios of carbon emission making sense in terms of conservation of mass between emissions and the natural removal of carbon dioxide. This implies that participants came to think of pattern matching that carbon emission would continue to increase as they used correlation graphs of carbon emission: that is, the graphs of the evolution of anthropogenic emissions, of atmospheric $CO_2$, and of global mean temperature, from the beginning of the Industrial Revolution up to date, all of which are shown in high school earth science textbooks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2267-2275
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• 2013

Existing conventional model for analysis of shallow water flow just assumed the internal boundary condition as free-slip, which resulted in the wrong prediction about the velocity, vorticity, water level, shear stress distribution, and time variation of drag and lift force around a structure. In this study, a finite element model that can predict flow characteristics around the structure accurately was developed and internal boundary conditions were generalized as partial slip condition using slip length concept. Laminar flow characteristics behind circular cylinder were analyzed by varying the internal boundary conditions. The simulation results of (1) time variations of longitudinal and transverse velocities, and vorticity; (2) wake length; (3) vortex shedding phenomena by slip length; (4) and mass conservation showed that the vortex shedding had never observed and laminar flow like creeping motion was occurred under free-slip condition. Assignment of partial slip condition changed the velocity distribution on the cylinder surface and influenced the magnitude of the shear stress and the occurrence of vorticity so that the period of vortex shedding was reduced compared with the case of no slip condition. The maximum mass conservation error occurred in the case of no slip condition, which had the value of 0.73%, and there was 0.21 % reduction in the maximum mass conservation error by changing the internal boundary condition from no slip to partial slip condition.

• Journal of Conservation Science
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• v.32 no.3
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• pp.333-343
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• 2016

A study on conservation of outdoor painted sculptures has begun to receive attention as increasing numbers of the sculptures, but it is still in an early stage in South Korea. In the case of a painted outdoor object which has been exhibited in National Museum of Modern and Contemporary Art (MMCA), 'Black nana' produced by Niki de Saint Phalle in 1964, deterioration was observed, such as flaking and discolouration of paint layers due to ultraviolet light and a sudden temperature change during an outdoor exhibition. For this reason, prior to treatment of the sculpture, to find out the painting techniques and materials applied, cross section, FT-IR, Raman and Py-GC/Mass were conducted. As a result, the type and colour of the paint agree with results of the other studies as well as deterioration pattern. It is expected that the results of this study will be utilized for treatment proposal and conservation material selection of 'Black nana'. In addition, to determine the artist's intention of the artist, cooperation with the foundation of Niki de Saint Phalle and artist's assistants will be carried out.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1269-1283
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• 2011

Here we consider magneto-convection in a mushy layer which is formed during solidification of binary alloys. The mushy layer is treated as an active porous media with variable permeability. The equations governing the layer are conservation of mass, conservation of heat, conservation of solute, magnetic induction equation, momentum equation governed by the Darcy's law and Maxwell's equations for the magnetic field. To study the second order effects on the flow without solving the second order system, we need to obtain the adjoint system for the flow. This motivates the authors we derive the adjoint system analytically for the mushy layer case. Numerical results of the adjoint system are presented for passive and active mushy layers at the onset of the motion using a set of parameters experimentalists use.