• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05a
• /
• pp.489-494
• /
• 1997

A comparative transient analyses were performed for oxide and nitride cores or a large (3000 MWt), pool-type, liquid-metal-cooled reactor (LMR). The study was focused on three representative accident initiators with failure to scram : the unprotected loss-of-flow (ULOF), the unprotected transient overpower (UTOP), and the unprotected fast transient overpower (UFTOP). The margins to fuel melting and sodium boiling have been evaluated for these representative transients. The results show that there is an increase in safety margin with nitride core which maintains the physical dimensions of the oxide core.

• Journal of the Korean Mathematical Society
• /
• v.43 no.2
• /
• pp.297-309
• /
• 2006

In this paper, we consider cooperative games arising from integer domination problem on graphs. We introduce two games, ${\kappa}-domination$ game and its monotonic relaxed game, and focus on their cores. We first give characterizations of the cores and the relationship between them. Furthermore, a common necessary and sufficient condition for the balancedness of both games is obtained by making use of the technique of linear programming and its duality.

• Journal of The Korean Astronomical Society
• /
• v.11 no.1
• /
• pp.55-58
• /
• 1978

An extensive molecular equilibrium calculation has been performed under sunspot conditions in order to resolve the current dispute on the presence of $C_2$ lines in the spectrum of sunspots. Equilibrium abundance of $C_2$ has been computed under the conditions of umbral cores, umbrae and the normal photosphere. As the results, it is found that the umbral cores yield unfavorable environment for $C_2$ formation. It is concluded that $C_2$ molecular lines are not likely tn be observed in the spectrum of sunspots.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1183-1184
• /
• 2006

Core loss of soft magnetic powder cores have been focused on to achieve high efficiency of power supplies. In this study the effects of crystal grain size on core loss were investigated by changing heat treatment conditions. It was found that core loss is influenced by crystal grain size because eddy current loss decreased and hysteresis loss increased by making crystal grain size smaller, and it is also influenced by particle size.

• Imaging Science in Dentistry
• /
• v.37 no.4
• /
• pp.211-215
• /
• 2007

Purpose: The purpose of this study was to evaluate the effect of the kV on fractal dimension of trabecular bone in digital radiographs. Materials and Methods: 16 bone cores were obtained from patients who had taken partial resection of tibia due to accidents. Each bone core along with an aluminum step wedge was radiographed with an occlusal film at 0.08 sec and with the constant film-focus distance (32 cm). All radiographs were acquired at 60, 75, and 90 kV. A rectangular ROI was drawn at medial part, distal part, and the bone defect area of each bone core image according to each kV. The directional fractal dimension was measured using Fourier Transform spectrum, and the anisotropy was obtained using directional fractal dimension. The values were compared by the repeated measures ANOVA. Results : The fractal dimensions increased along with kV increase (p < 0.05). The anisotropy measurements did not show statistically significant difference according to kV change. The fractal dimensions of the bone defect areas of the bone cores have low values contrast to the non-defect areas of the bone cores. The anisotropy measurements of the bone defect areas were lower than those of the non-defect areas of the bone cores, but not statistically significant. Conclusion: Fractal analysis can notice a difference of a change of voltage of x-ray tube and bone defect or not. And anisotropy of a trabecular bone is coherent even with change of the voltage of x-ray tube or defecting off a part of bone.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.18 no.3
• /
• pp.41-49
• /
• 2012

Most large-sized and tall-risen general hospitals of today fairly depend on in-patient wards in designing hospital styles. The core planning for the efficient movements of various people in the words should take into account the sustainable connections between/among the floors, as well as hospital structures and mechanical functions. This study sampled for the study 19 hospital in-patient wards and investigated their flat-core styles. It was found out that hospital structures are changing from symmetrical styles of triangles, quadrangles and rectangles through bending, configuring, transforming to efficient new styles. Symmetrically quadrangled flat-styles are made of multi-cores spread with main an sub-cores. In contrast, symmetrically triangled flat-styles place the open place in the middle in order to prevent from its deepening, and widened the depth line through changing the outdoor top point. Non-symmetrical rectangles minimized the depth value to maintain the recent styles used in the wards, and tended to prefer the transformed styles of quadrangles. The double-corridors easily transshaped from mono corridors reveals the triangled, W-shaped, or Y-shaped figures. The site area ratio of the cores is 11.95% in average. The number of beds which one elevator covers is 66.51 beds in average, and the size of site area which one elevator covers 216.68m. Most cores on the base floor clustered around the average value, with more than 1000 beds shoes 12.83%, does 12.93%, does 14.64%, does 14.58%, which says that the core ratio increases according to hospital beds.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.8
• /
• pp.82-90
• /
• 2004

The mechanical characteristics of three types of core with two-dimensional isotropic patterns-triangular, hexagonal and starcell-were studied in applications to sandwich structures. The Young's modulus and shear modulus were calculated for the three core types in the direction normal to the faces. The compressive buckling strength and shear buckling strength were calculated by modeling each cell wall of the core as a plate under compressive or shear load. To verify this model, tests were conducted on scaled specimens to measure the compressive buckling strength of each core. The bending flexibilites of the three cores were also studied. Compliances for the three cores were measured using biaxial flexural tests. The three isotropic core patterns exhibited distinct characteristics. In the direction normal to the faces, all three cores had the same stiffness. However, the starcell core exhibited high flexibility compared to the other cores, indicating potential for application to curved sandwich structures.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.6
• /
• pp.1064-1074
• /
• 1992

Eliminating the under-cut caused by interference between a mold and a product in designing a mold for in jection molding processes is a very important problem. In general, the under-cut problem can be avoided by side cores which are the principal members of a mold assembly. In this research, a procedure has been developed by which the side cores and the corresponding core and cavity plates of a mold are generated after identifying the mold faces preventing product faces from moving while being discharged. The characteristic features of the procedure suggested in this paper are as follows. One is that the interference faces between the product and the mold are derived only from the core plate(or cavity plate) alone without considering the product together. The other is that the algorithm in the designing of side cores and modifying molds, is very efficient because it uses Euler operations instead of Boolean operations.

• Korean Journal of Optics and Photonics
• /
• v.15 no.1
• /
• pp.12-16
• /
• 2004

We show that the extinction ratio is improved using slight asymmetry in two core refractive indices of polarization independent very short vertical directional couplers with the double-sided deep-ridge (DSDR) waveguide structure. The optimum asymmetry with the maximum extinction ratio and the tolerance of the refractive index of core with the extinction ratio larger 1ha]1 30 ㏈ increase as the thickness of inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. Also, the device length and the tolerance of the device length with the extinction ratio larger than 30 ㏈ decrease as the thickness of the inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. We show that polarization independent vertical directional couplers with the DSDR waveguide structure with the device length less than 100 ${\mu}{\textrm}{m}$ and the extinction ratio larger than 30 ㏈ could be implemented.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.16 no.3
• /
• pp.291-299
• /
• 2003

Based on the continuum approach, an investigation is made to get the forces and displacements of laterally loaded outrigger braced structures with a pair of coupled cores, and to show the effect of stiffening outriggers on the behavior of the structure. From the condition that the rotation of the core at the outrigger level is matched with the rotation of the corresponding outrigger, the outrigger restraining moment is derived analytically. From this, the core moment diagram, the column axial forces, and the horizontal displacements of the structure may be determined. Comparisons with the results by the program MIDAS-GEN for the structural models, have shown that this analysis can give reasonably accurate results for outrigger-braced structures with a pair of coupled cores. And a lateral displacement at the top of the structure is influenced by the outrigger location than the core location. Although the formulae are accurate only for idealized outrigger braced structures, they have a useful practical purpose in providing a guide to the behavior, and for making approximate estimates of the forces and displacements, in practical outrigger braced structures with a pair of coupled cores.