• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.32.1-32.1
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• 2014

Astronomical observations strongly suggest that the expansion rate of our universe is currently under acceleration. The nature of the so-called dark energy causing the acceleration is unknown, and it is one of the fundamental mysteries in the present day theoretical cosmology. Here we briefly review the current state of cosmic dark energy research in both theoretical and observational sides. Constraints on dynamical dark energy models (e.g., w-fluid, quintessence, and modified gravity) with recent observational data from type Ia supernovae, cosmic microwave background radiation, and large-scale structures in the universe indicate a preferred direction toward the simplest ${\Lambda}$CDM world model. We also discuss some issues regarding the early dark energy model and the spherical collapse of matter in the presence of dark energy.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.423-428
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• 2010

In the initial design phase of superscalar microprocessors, a performance model is necessary. A theoretic performance model is very useful since performance for various architecture parameters can be obtained by simply computing equations, without repeating simulations, Previous studies established theoretic performance models using the relation between the instruction window size and the issue width, with the penalties due to branch mispredictions and cache misses. However, the study was intended for unlimited number of functional units, which is insufficient for the real case application. This paper proposes a superscalar microprocessor theoretical performance model which also works for the limited functional units. To enhance the accuracy of our limited functional unit model, instruction dependency rates are employed. By using trace-driven data of SPEC 2000 integer programs as input, this paper shows that the theoretically computed performance of superscalar microprocessor with limited number of functional units is quite similar to the measured performance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.317-324
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• 2003

Kriging interpolation is one of the gennerally used interpolation techniques in Geostatics field. This research refers to the contents about important experimental variogram and the study of theoretical variogram and formulation of Kriging interpolation. Kriging interpolation is applied as interpolation for stress smoothing in finite element method. Posteriori error estimation which makes use of stress smoothing from the FEM is very important part, we try to make practical application of surface regeneration ability from Kriging interpolation. This research is necessary preceding one in order to materialize adaptive FTM through posteriori error estimation. For instance, find the estimate value and estimate the propriety through various theoretical variogram models of the reference analyzed from tensional L-shape domain. It also provides possibility of the Kriging interpolation through comparing to existing Least square method as well.

• Journal of the Korean Society of Marine Environment & Safety
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• v.7 no.3
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• pp.107-116
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• 2001

The relatively rapid rising trends of crime rates in marine situations leads to social concerns in Korea. This study reviews some theoretical backgrounds of the economics of crime and apply econometric models to Korean marine crimes. We find that there is a positive relationship between marine crime rates and unemployment rates in Korea and the degree of the relationship is higher in the 1990s' in comparison with the results of 1970s' and 1980s'. This findings are compatible with the previous theoretical researches in advanced countries. These findings show that recently the structure of our economy and the economic behaviors of economic agents in Korea have been similar to those of the advanced economies. Therefore this study shows that there exists the additional social costs of economic depression by causing the social crimes and the necessity of public policies to reduce unemployment rates would be higher.

• Journal of the Korean Ceramic Society
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• v.43 no.11 s.294
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• pp.673-679
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• 2006

The discovery of ferroelectric barium titanate (BaTiO$_3$) in 1942 began the present era of dielectrics-based electronic ceramics. Ferroelectric barium titanate has a high dielectric constant and after the recognition of BaTiO$_3$ as a new ferroelectric compound, various attractive electrical properties have been extensively studied and reported. Since then, pioneering work on valence-compensated semiconduction led to the discovery of the positive temperature coefficient (PTC) of the resistance effect found in doped BaTiO$_3$. Significant progress has since followed with respect to understanding the PTC phenomena, advancing materials capabilities, and developing devices for sensor and switching applications. In this paper, the theoretical aspects of the various PTC models are discussed and the future trends of practical applications for PTC devices are briefly mentioned.

• Genomics & Informatics
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• v.2 no.1
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• pp.7-18
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• 2004

Integrated genomics refers to the use of large-scale, systematically collected data from various sources to address biological and biomedical problems. A critical ingredient to a successful research program in integrated genomics is the establishment of an effective computational infrastructure. In this review, we suggest that the computational infrastructure challenges include developing tools for heterogeneous data organization and access, innovating techniques for combining the results of different analyses, and establishing a theoretical framework for integrating biological and quantitative models. For each of the three areas - data integration, analyses integration, and model integration - we review some of the current progress and suggest new topics of research. We argue that the primary computational challenges lie in developing sound theoretical foundations for understanding the genome rather than simply the development of algorithms and programs.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.35.1-35.1
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• 2010

Using the spectroscopic analysis and the theoretical modeling, physical properties of the nearby astrometric binary $\mu$ Cas have been determined. In spite of the well-defined parallax and astrometric orbit, there has been a chronic mass ratio problem between components. Recently, the radius of the primary component has been detected from the optical interferometric observation of the CHARA array. Using the high resolution spectroscopic analysis, we found that $\mu$ Cas have $\alpha$-enhanced chemical composition with respect to the scaled solar abundance by a factor of two. Combining our abundance analysis with recently determined physical properties, the consistent models for $\mu$ Cas have been constructed within the frame work of standard stellar theory. Through a statistical minimization between theoretical model grids, a reliable set of physical dimensions has been defined. Furthermore, the mode oscillation frequency of the best model has been calculated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2049-2054
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• 2006

This paper demonstrates a comparison of linear and nonlinear analyses for thermo-optic effects of optical temperature sensor based on the etched silica-based planar waveguide Bragg grating. Topics include theoretical analyses and experiment of the etched planar waveguide Bragg grating optical temperature sensor, Theoretical models with nonlinear than linear temperature effect for the grating response based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

• Coupled systems mechanics
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• v.4 no.2
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• pp.191-209
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• 2015

Hybrid girders can be constructed in different geometrical forms and from different materials. Selection of beam's effective constellation represents a complex process considering the variations of geometrical parameters, changes of built in material characteristics and their mutual relations, which has important effect on the behavior of the girder. This paper presents the theoretical and experimental research on behavior of the timber-steel hybrid girders' different geometrical constellation with external prestressing and in different conditions of timber moisture. These researches are based on linear elastic analysis, and further refine by using the plasticity and damage models.

• Computers and Concrete
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• v.24 no.3
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• pp.259-269
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• 2019

The work aims at the comparison among commonly used research programs concerning moment-curvature ($M-{\chi}$) diagrams of confined R.C. members. The software considered in this work are Sap2000, SeismoStruct and Opensees. The curves provided by these software, given the same modelling, have been compared to those provided by a theoretical fiber model. A parametric analysis has been led on rectangular column sections with different level of axial load and different stirrups spacing. The accuracy of the modelling of the considered structural programs has been investigated by comparing their results with those obtained by applying the theoretical fiber model.