• Korean Journal of Materials Research
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• v.5 no.2
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• pp.157-168
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• 1995

The effects of Mo additions on the microstructure and the room temperature deformation behavior of polysynthetically twinned (PST) crystals of TiAl were studied in order to get a basic conception for alloying additions on the two-phase TiAl compounds with the lamellar structure. It was found that the Mo additions in TiAl PST crystals increase both the yield stress and tensile elongation to fracture but the increase in yield stress deppend on the angle $\Phi$at which the lamellar boundaries lie from the loading axis. The large difference in yield stress between specimens deformed parallel($\Phi = 0^\circ$)or perpendicular($\Phi = 90^\circ$) to the loading axis and those deformed in intermediate orientations could be plained by the difference in Mo content between the TiAl and the $$Ti_{3}Al$ phases. It was also found that the Mo-doped specimens with intermediate orientation fail by cracking zigzag across to the lamellar boundaris, which is the same fracture mode as that of binary specimens with intermediate orientations tested in vacuum This suggests that Mo atoms are thought to play a role to reduce the environmental embrittlement of binary PST crystals, resulting in increasing the tensile ductility.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.5-13
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• 2005

Acoustic emission(AE) is defined as the transient elastic waves thar are generated by the rapid release of energy. The advantage of AE is that very early crack growth can be detected well before a highly stressed component may fail. At present, an exact diagnosis is the most reliable means for determining the soundness of structures during power plant operations. AE monitoring has been applied successfully in power plants to determine mechanical problems, pressure vessel integrity and external valves leaks, vacuum leaks, the onset of cavitation in pumps and valves, the presence of flow(or no flow) in piping and heat exchange equipment, etc. Acoustic emission(AE) technology has recently strengthened its application base, and practitioners' understanding of the technique's fundamentals. This paper introduces the methods of a survey and assessment on AE monitoring applications in nuclear, fossil and hydraulic power plant. The main objective of this paper was to obtain information on various applications of AE technology in power plant.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.174-174
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• 2000

A strong antiferromagnetic coupling in Fe/Si multilayered films (MLF) had been recently discovered and much consideration has been given to whether the coupling in the Fe/Si MLF system has the same origin as the metal/metal MLF. Nevertheless, the nature of the interfacial ron silicide is still controversial. On one hand, a metal/ semiconductor structure was suggested with a narrow band-gap semiconducting $\varepsilon$-FeSi spacer that mediates the coupling. However, some features show that the nature of coupling can be well understood in terms of the conventional metal/metal multilayered system. It is well known that both magneto-optical (MO) and optical properties of a metal depend strongly on their electronic structure that is also correlated with the atomic and chemical ordering. In this study, the nature of the interfacial regions is the Fe/Si multilayers has been investigated by the experimental and computer-simulated MO and optical spectroscopies. The Fe/Si MLF were prepared by rf-sputtering onto glass substrates at room temperature with the number of repetition N=50. The thickness of Fe sublayer was fixed at 3.0nm while the Si sublayer thickness was varied from 1.0 to 2.0 nm. The topmost layer of all the Fe/Si MLF is Fe. In order to carry out the computer simulations, the information on the MO and optical parameters of the materials that may constitute a real multilayered structure should be known in advance. For this purpose, we also prepared Fe, Si, FeSi2 and FeSi samples. The structural characterization of Fe/Si MLF was performed by low- and high -angle x-ray diffraction with a Cu-K$\alpha$ radiation and by transmission electron microscopy. A bulk $\varepsilon$-FeSi was also investigated. The MO and optical properties were measured at room temperature in the 1.0-4.7 eV energy range. The theoretical simulations of MO and optical properties for the Fe/Si MLF were performed by solving exactly a multireflection problem using the scattering matrix approach assuming various stoichiometries of a nonmagnetic spacer separating the antiferromagnetically coupled Fe layers. The simulated spectra of a model structure of FeSi2 or $\varepsilon$-FeSi as the spacer turned out to fail in explaining the experimental spectra of the Fe/Si MLF in both intensity and shape. Thus, the decisive disagreement between experimental and simulated MO and optical properties ruled out the hypothesis of FeSi2 and $\varepsilon$-FeSi as the nonmagnetic spacer. By supposing the spontaneous formation of a metallic ζ-FeSi, a reasonable agreement between experimental and simulated MO and optical spectra was obtained.

• The Journal of Korean Philosophical History
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• no.39
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• pp.29-52
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• 2013

Philosophy of respect righteousness advocated by Nammyung points to what first needs to be done to drive social changes. It is consistent with the Confucianism, which views the world from within oneself. After all, developing a proper view of the society starts from looking at oneself in the right perspective. The view that personal cultivation can develop into cultivation and eventually reform of the entire society is also present in Confucius' belief that one can only be at peace after disciplining oneself and observe good manners only after perseverance. Also, one can lead the world in peace only after disciplining one's body and mind. In other words, it suggests that individuals and the community where they belong to are not independent from one another. Rather, individuals gather to create a society and righteous individuals are the basis for righteous society. These principles of social system in Confucianism can be understood as a mutual or layered division and integration. The society is not conflicted with individuals or the nation but rather perceived as moral communities to co-exist. Hence, power of execution observed in the philosophy of respect and righteousness by Nammyung is identical to power of execution applied to the society. The power of execution shows up as 'the execution of righteousness' in Nammyung's philosophy of respect and righteousness. It is also demonstrated in the acts by Nammyung's disciples when the nation was at crisis. This is what differentiates Nammyung's new-Confucianism in Joseon Dynasty from Toegye or Yulgok as he tried to deliver 'the execution of righteousness.' It does not mean that neo-Confucian scholars did not emphasize the importance of execution, but Nammyung, in particular, warned how deceitful ideological or inner-directed thinking can be since they fail to come up with concrete solutions to social issues. In summary, Nammyung's moral discipline and training based on respect and righteousness cannot be evaluated in a state of vacuum separate from social and historical aspects but under the context of enlightening virtue and social execution. This can draw the conclusion that Nammyung's execution of respect and righteousness is in the starting point of the realistic 'theory of social reform' for creating a better world.