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- Baek, Seung Ki, 1979-, et al.
(författare)
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Numerical Study of Game Theory
- 2010
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Ingår i: New Physics. - Seoul : The Korean Physical Society. - 0374-4914. ; 60:9, s. 943-951
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Game-theoretic approach has been providing a powerful tool in qualitative understanding of macroscopic social phenomena in social sciences, e.g., in economics and political science. Recently, researchers in physics, especially in statistical physics, use these game-theoretic approaches but in more quantitative way and have been producing a variety of interesting results in the new research area called ’sociophysics’ by studying human society as a complex system. This work introduces recent works that have tackled combinatorial complexities arising in game-theoretic studies with the aid of simplified assumptions and numerical computations. We first show how cooperation emerges in the prisoner’s dilemma game when each player’s memory capacity is enhanced and suggest that the intelligent tit-for-tat strategy plays a crucial role in the history of cooperation. And then it is numerically shown that there is a certain case of simultaneous coordination among many players where the system has a high risk of failure when everyone is willing to follow the coordination, which is actually higher than when some are not concerned about it. Lastly, we discuss mathematical treatment of an equilibrium solution for a reverse auction game, which is a variant of the minority game, and its computational approach.
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| 2. |
- Choi, Hyun-Ju
(författare)
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Image analysis for quantifying microvessel density in renal cell carcinoma
- 2009
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Ingår i: Journal of Korea Society of Medical Informatics. - : The Korean Society of Medical Informatics. - 1225-8903. ; 15:2, s. 217-225
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Tidskriftsartikel (refereegranskat)abstract
- The most widely used method for quantifying new blood vessel growth in tumor angiogenesis is the determination of microvessel density, which is reported to be associated with tumor progression and metastasis, and a prognostic indicator of patient outcome. In this study, we propose a method for the determination of microvessel density by image analysis, to improve the accuracy and the objectivity of determination of the microvessel density. Four-micron-thick tissue sections of renal cell carcinoma samples were stained immunohistochemically for CD34. The regions with a high degree of vascularization were selected by an expert for digitization. Each image was digitized as a 24-bits/pixel image file with a resolution of 640×480 pixels. First, segmentation of the microvessels based on pixel classification using color features in hybrid color space was performed. After use of a correction process for microvessels with discontinuities and separation of touching microvessels, we counted the number of microvessels for the microvessel density measurement. The result was evaluated by comparison with manual quantification of the same images. The comparison revealed that our computerized microvessel quantification was highly correlated with manual counting by a pathologist. The results indicate that our method is better than the conventional computerized image analysis methods.
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| 3. |
- Chung, S., et al.
(författare)
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Effect of MgO Insertion between Topological Insulator Bi2Se3 and Ferromagnet NiFe Multilayer Structures
- 2022
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Ingår i: Journal of the Korean Magnetics Society. - : The Korean Magnetics Society. - 1598-5385 .- 2233-6648. ; 32:1, s. 27-31
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Tidskriftsartikel (refereegranskat)abstract
- We study ferromagnetic resonance (FMR) properties of topological insulator Bi2Se3 and ferromagnet NiFe (permalloy) multilayer structures. We found that Bi2Se3/NiFe shows two times larger magnetic damping than that of single NiFe, which indicates strong spin pumping exists in the interface between Bi2Se3 and NiFe. Also, 1 nm thick MgO layer was inserted into between Bi2Se3 and NiFe, where spin-pumping is expected to be suppressed. Bi2Se3/MgO/NiFe shows same amount of spin-pumping effect as observed in Bi2Se3/NiFe, while thin MgO layer can be beneficial for suppressing the formation of magnetic dead layer. These results show that 1 nm thick MgO can be utilized as a good spacer layer without a loss of spin-pumping in the multilayer structures with topological insulator.
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| 4. |
- Jo, Ji Song, et al.
(författare)
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Anti-wrinkle activity of beta-carotene extracted & purified from recombinant Escherichia coli
- 2008
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Ingår i: KSBB Journal. - 1225-7117 .- 2288-8268. ; 23:6, s. 513-518
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Tidskriftsartikel (refereegranskat)abstract
- This paper described the extraction/purification of β-carotene from recombinant E.coli and evaluation of anti-wrinkle activity of purified β-carotene. No significant differences in extraction yields were observed when hexane or isobutyl acetate was used. However, extraction from wet-cell cake resulted in 2-fold higher amount of β-carotene than that from dry cells. Disruption of 5 g-wet cells by ultrasonic homogenizer, acetone dehydration, extraction with isobutyl acetate resulted in 36 mg of β-carotene corresponding to 61.2% of recovery. The formation and separation of ββ-carotene crystal improved the purity. 633 mg of β-carotene crystal with 93% purity was obtained from 223 g/L of wet-cell cake harvested from 2.5-L fed-batch culture broth. The cultures of normal human primary fibroblast were performed to investigate the effect of β-carotene on cytotoxicity as MTT assay and anti-wrinkle activity as collagen synthesis assays. 1.7μM of β-carotene was found to be optimal concentration at which 1.4-fold higher amount of collagen was synthesized than that in absence of β-carotene. This indicates that highly purified β-carotene can be obtained from recombinant E.coli by applying simple method with less toxic solvent and can be used in functional cosmetics as anti-wrinkle agent.
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| 10. |
- Kim, Kwangsu, et al.
(författare)
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A Devolatilization Model of Woody Biomass Particle in a Fluidized Bed Reactor
- 2012
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Ingår i: Korean Chemical Engineering Research. - 2233-9558 .- 0304-128X. ; 50:5, s. 850-859
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Tidskriftsartikel (refereegranskat)abstract
- Devolatilization is an important mechanism in the gasification and pyrolysis of woody biomass, and has tobe accordingly considered in designing a gasifier. In order to describe the devolatilization process of wood particle, therehave been proposed a number of empirical correlations based on experimental data. However, the correlations are limitedto apply for various reaction conditions due to the complex nature of wood devolatilization. In this study, a simplemodel was developed for predicting the devolatilization of a wood particle in a fluidized bed reactor. The model consideredthe drying, shrinkage and heat generation of intra-particle for a spherical biomass. The influence of variousparameters such as size, initial moisture content, heat transfer coefficient, kinetic model and temperature, was investigated.The devolatilization time linearly increased with increasing initial moisture content and size of a wood particle,whereas decreases with reaction temperature. There is no significant change of results when the external heat transfercoefficient is over 300 W/m2K, and smaller particles are more sensitive to the outer heat transfer coefficient. Predictedresults from the model show a similar tendency with the experimental data from literatures within a deviation of 10%.
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