• Macromolecular Research
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• v.14 no.2
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• pp.220-229
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• 2006

Several equations of state for hard-sphere chains with various perturbation terms are reviewed. For each model, three characteristic parameters are required to represent phase equilibria of normal fluids and obtained from thermodynamic properties of pure saturated liquids. The models are then compared with computer simulation data to show the effect of attractive contribution forms employed. Calculated values of vapor-liquid equilibria (VLE) of hydrocarbons that can be reproduced for each model are also compared with experimental results. An additional parameter, ${\zeta}_{KB}$, is required to represent the VLE of pure water, which is ascertained to have a strong influence on the theoretical coexistence curve.

• Geomechanics and Engineering
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• v.14 no.1
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• pp.19-27
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• 2018

It follows from the basic principles of mechanics of deformable solids relating to the strength, stability and propagation of elastic waves that the Earth's inner core cannot exist in the form of a spherical structure in the assumed thermobaric conditions and calculation values of physico-mechanical parameters. Pressure level reaches a value that is significantly greater than the theoretical limit of medium strength in the model approximations at the surface of the sphere of the inner core. On the other hand, equilibrium state of the sphere is unstable on the geometric forming at much lower loads under the influence of the "dead" surface loads. In case of the action of "follower" loads, the assumed pressure value on the surface of the sphere is comparable with the value of the critical load of "internal" instability. In these cases, due to the instability of the equilibrium state, propagation of homogeneous deformations becomes uneven in the sphere. Moreover, the elastic waves with actual velocity cannot propagate in such conditions in solid medium. Violation of these fundamental conditions of mechanics required in determining the physical and mechanical properties of the medium should be taken into account in the integrated interpretations of seismic and laboratory (experimental) data. In this case, application of the linear theory of elasticity and elastic waves does not ensure the reliability of results on the structure and composition of the Earth's core despite compliance with the required integral conditions on the mass, moment of inertia and natural oscillations of the Earth.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.89-96
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• 2009

The present study is performed to identify the relationship between apartment prices and distances from freeway interchanges. To collect consistent data and to simplify the sphere of the influence, the Seoul beltway was selected as the target road. Two sides of the Seoul beltway such as the inner side and the outer side are partitioned following the whole beltway line. The maximum distance to be taken care of in data collection was 6.0km from freeway interchanges. Results show that there exist consistent patterns between apartment prices and distances from freeway interchanges. In detail, if the apartment is located on the sphere of the influence, it is shown that a) the prices are increased overall b) the prices are low at very near of interchanges c) the prices are increasing up to the points of about 2.0~4.0km from interchanges d) the prices are decreasing after the points. Additionally, it is shown the pattern observed was following approximately a quadratic curve which is different from the liner curve obtained from the similar study over the sphere of the influence in railway(Subway).

• Journal of the Optical Society of Korea
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• v.20 no.4
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• pp.500-509
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• 2016

Integrating spheres play a central role in the radiometric calibration of remote sensors. With the development of the wide field of view (FOV) remote sensors, aperture diameters of remote sensors are becoming larger and larger. To satisfy the radiometric calibration requirements of full FOV and full aperture, an 8000mm diameter large aperture integrating sphere uniform source with a variable exit port was designed and manufactured. This integrating sphere will be used for pre-launch test and radiometric calibration of remote satellites. In this paper, optical theories were used to design the output spectral radiance. The LightTools software based on ray-tracing simulation method was used to determine the best combination and distribution of inner light sources. A spectral experiment was made to verify the spectral radiance design. To reduce the influence of longtime power-on, a new characteristic measurement method was developed to obtain the radiation characteristic of the integrating sphere, which could greatly improve the measuring efficiency. This method could also be applied to measure other large aperture uniform sources. The obtained results indicate that the spatial uniformity is 98.35%, and the angular uniformity at center position is 98.78%.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04b
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• pp.309-314
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• 1999

With a view to seek the influence of hollow sphere pigments of latex upon the printed color on coated paper surface, the hollow sphere pigments were compared with filled ones in a variety of experimental approaches. Colloidal properties of latices were determined by measuring zeta potential and particle size distribution. For the amphoteric filled sphere pigment of latex, the polarity was reversed from the negative side to the positive side with decreasing pH. An extraordinarily high peak in the particle size distribution of the amphoteric filled evidenced aggregation between latex particles near the isoelectric point, depending on the electrolyte concentration and pH of the suspending medium. Coated papers containing the hollow sphere pigment in their coating improved optical properties like gloss and brightness. Optical parameters solely of the coating could account for this finding. An equation derived from the Kubelka-Munk equation calculated them fro twice measurements of reflectance of a coated paper over two substrates of different reflectances. This method permitted to predict brightness of coated paper of which coat weight would be different fro the actual one. The colorimetric parameters of solid-printed surfaces of the coated papers closely related to optical and structural properties of the coated papers. The color of the printed surfaces was dominated by the brightness and the smoothness of the coated papers. The hollow sphere pigments were proved to improve optical properties of coated paper and to control minutely colorimetric parameters of printed surfaces.

• Journal of Korean society of Dental Hygiene
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• v.10 no.5
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• pp.877-885
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• 2010

Objectives : This study was carried out with the aim of utilizing it as basic data in a plan for oral health promotion by analyzing oral-health awareness in high school students of some districts in our country, and by analyzing physical, mental and social influential factors in oral health, through using OHIP(Oral Health Impact Profile). Methods : It surveyed by carrying out self-administered questionnaire research targeting 536 boy & girl high school students in the 1st and the 2nd grade at 3 high schools in some districts of Gyeonggi Province. Results : 1. As for experience of having not visited dental clinic, a case of having not visited accounted for 32.5%. On the other hand, a case of having visited accounted for 67.5%. As for the appearance of oral health education, only 2.8% responded as saying of having experience. 97.2% responded as saying of having not taken oral health education. 2. As for oral health state perceived by oneself, the response as saying of 'thinking it to be healthy' and that 'there is something wrong' showed the distribution of 34.1% that is the same ratio. As for oral health interest, a case of having a little interest(58.4%) or of being so much interested(12.5%) showed 70.9%. A case of having no special interest(24.8%) or of having no interest at all(4.3%) showed the level of 29.1%.3. As for oral health knowledge, the toothbrushing knowledge was the highest with 4.54 marks out of 6-point perfection. The toothbrush knowledge(4-point perfection) showed low point with 2.05 marks. 4. By gender, a case of men was high in OHIP(Oral Health Impact Profile) for the functional restriction and physical pain. On the other hand, in the remaining sphere, women were indicated to be high in OHIP. The statistically significant difference was indicated in the spheres such as physical pain, psychological discomfort, a drop in psychological ability, a drop in social ability, and social separation. 5. According to oral health state perceived by oneself, a case of thinking it to be healthy was indicated to be high in OHIP for every sphere. A case of thinking it to have gum disease was indicated to be low in OHIP for every sphere. The statistically significant difference was indicated in every sphere except the sphere of functional restriction. 6. As for a factor of having influence upon OHIP according to oral health knowledge, it was indicated that the higher toothbrush knowledge leads to having more influence upon OHIP. Conclusions : It could be known that the oral health knowledge and OHIP are varied as well according to the oral health interest level. Also, the oral health education proper for subjects is not being performed. Even as for frequency of visiting the dentist, a regular visit is failing to be made. In consideration of these points, the diversified and effective educational program is likely considered to be necessarily developed and improved that subjects can have more interest in oral health.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.81-92
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• 1992

This paper deals with the procedure for developing a computer program which can predict the pressure fluctuation on the ship hull by solving the boundary value problem on the hull subject to the influence of the unsteady propeller and cavity motions. The program is applied to the solution of flow around a sphere under the influence of point sources simulating the propeller cavity, and then is compared with the analytic solution based on Butler's sphere theorem. The effect of free surface condition, either pressure-free or rigid-wall, upon the pressure distribution is studied. The computer code is also applied to a RO-RO ship, leading to the conclusion that the package may be useful for the analysis of excitation forces on the ship hull induced by the propeller in the design process.

• Structural Engineering and Mechanics
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• v.46 no.4
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• pp.571-594
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• 2013

Railway truss bridges are amongst the essential structures in railway transportation. Minimization of the construction and maintenance costs of these trusses can effectively reduce investments in railway industries. In case of railway bridges, due to high ratio of the live load to the dead load, the moving load has considerable influence on the bridge dynamics. In this paper, optimization of the railway truss bridges under moving load is taken into consideration. The appropriate algorithm namely Hyper-sphere algorithm is used for this multifaceted problem. Through optimization the efficiency of the method successfully raised about 5 percent, compared with similar algorithms. The proposed optimization carried out on several typical railway trusses. The influences of buckling, deformation constraints, and the optimum height of each type of truss, assessed using a simple approximation method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.262-265
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• 2002

Fused deposition modelling(FDM) is a rapid prototyping(RP) process that fabricates part layer by layer by deposition of molten thermoplastic material extrude from a nozzle. RP system has many benefit. One of the benefit would be the ability to experiment wiか physical objects of my complexity in a relatively short period of time. But it has a matter of surface roughness and geometric accuracy. We study on Influence of angle of tangent line and area error on sphere surface roughness at fused deposition.

• Transactions of the Korean hydrogen and new energy society
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• v.9 no.3
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• pp.119-125
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• 1998

The modified statistical-mechanical theory for dense fluid mixtures of rigid spheres has been applied to rigid sphere fluids in the nonoverlapping pore model. The resulting expressions for the partition coefficient and diffusivity illustrate the influence of steric hindrance on the thermodynamic and transport properties in such systems. The open membrane model without the size-exclusion and shielding effects shows considerable overestimation of the diffusion flux when the effective mean pore radii of the order of $20{\AA}$ or less are involved. Theoretical predictions investigated here were also compared with experimental data for hydrogen gases in inorganic porous membranes and it was observed a qualitative agreement in the low pressure limit.