• Title/Summary/Keyword: dislocation structure

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The Secondary Defect Structure in Al-Cu-Mg Alloy (Al-Cu-Mg 합금에 있어서의 2차 결함조직)

  • Cho, Hyun-Kee;Woo, Kee-Do
    • Applied Microscopy
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    • v.16 no.2
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    • pp.14-24
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    • 1986
  • The interrelation of secondary defects, intermediate S' phase and aging condition in Al-2.0 wt% Cu-1.1 wt% Mg alloy is studied by transmission electron microscope. The results obtained in this study are as follows. 1. High density of dislocation loops, helices and stacking faults are observed in this specimen with aging treatment. 2. The number of dislocation loops and the width of loop free zone (LFZ) are increased with aging time. 3. The intermediate S' phase precipitates and grows on the dislocations and secondary defects. 4. The misfit dislocations are formed around intermediate S' phase. 5. It is thought that the helices appear to be produced by the climb of screw dislocations, while the dislocation loops appear to be formed both by condensation of vacancies into collapsed discs and by interaction of helices with screw of opposite sign.

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Characteristics of Barkhausen Noise Properties and Hysteresis Loop on Tensile Stressed Rolled Steels

  • Kikuchi, Hiroaki;Ara, Katsuyuki;Kamada, Yasuhiro;Kobayashi, Satoru
    • Journal of Magnetics
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    • v.16 no.4
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    • pp.427-430
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    • 2011
  • The rolled steels for welded structure applied tensile stress have been examined by means of magnetic Barkhausen noise (MBN) method and of a physical parameter obtained from a hysteresis loop. The behaviors of MBN parameters and coercive force with tensile stress were discussed in relation to microstructure changes. There is no change in MBN parameters and coercive force below yield strength. The coercive force rises rapidly with tensile stress above yield strength. On the other hand, the rms voltage and the peak in averaged rms voltage take a maximum around yield strength and then decreases. The magnetomotive force at peak in the averaged rms voltage shows a minimum around yield strength. These phenomena are attributed to the combined effects of cell texture and dislocation density. In addition, the behaviors of MBN parameters around yield strength may be reflected by the localized changes in strain field due to the formation of dislocation tangles.

Dislocation/Particles Interaction and Threshold Stress in Precipitation-Hardened Al-0.55 wt% Zr Alloy with Fine Particles at High-Temperature (고온에서 미세입자를 가진 석출경화형 Al-0.55 wt% Zr 합금의 Threshold 응력과 전위/입자의 상호 작용에 관한 연구)

  • Kim, Byung I.;Nakashima, Hideharu
    • Journal of the Korean Society for Heat Treatment
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    • v.5 no.4
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    • pp.201-208
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    • 1992
  • An experimental study of the constitutive response of precipitation-strengthened Al-0.55wt% Zr alloy, which consists of an Al matrix precipitation-strengthened by coherent particles, ${\beta}^{\prime}(Al_3Zr)$ with $L1_2$ structure has been performed. The deformation response of the materials has been examined by stress relaxation test at 573K, 623K and 673K. It was found that there exist the threshold stress during stress relaxation and threshold stress results from the presense of ${\beta}^{\prime}(Al_3Zr)$ particles. The ratio of threshold stress and Orowan stress decreased gradually with increasing temperature. The resistance to climb-pass of particles was independent of particles size for a fixed volume fraction although the threshold for bowing and particles cutting are sensitive to the particles dimensions. The smaller particles cutted by dislocations. This behavior of dislocations in this alloy was explained in terms of the small value antiphase boundary energy. The dislocation networks wrere more extensive in spesimens subjected to stress relaxation and there were numerous areas that have a high denstiy of jogged dislocation. This experiment results indicate that the rate controlling stress relaxation process is the climb of edge dislocation over particles.

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Nanoindentation behaviours of silver film/copper substrate (Ag 필름/ Cu기판의 나노인덴테이션 거동 해석)

  • Trandmh, Long;Kim, Am-Kee;Cheon, Seong-Sik
    • Composites Research
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    • v.22 no.3
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    • pp.9-17
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    • 2009
  • Nanoindentation behaviours on the films of softer Ag film/harder Cu substrate structure were studied by the molecular dynamics method. As a result, it was shown that the stiffness and hardness of films were strongly dependent on the thickness of films. The stiffness and hardness increased with the thickness of film within a critical range as an inverse Hall-Petch relation. The stiffness and hardness of Cu substrate with Ag film less than 5 nm were observed to be lower than those of bulk silver. In particular, the flower-like dislocation loop was created on the interface by the interaction between dislocation pile-up and misfit dislocation during the indentation of Ag film/Cu substrate with film thickness less than 4 nm, which seemed to be associated with the drop of load in the indentation load versus displacement curve.

An Irreducible Posterolateral Dislocation of Knee by the Detached Femoral Cartilage - A Case Report - (대퇴 연골편에 의해 정복이 불가능한 슬관절 후외방 탈구 - 1예 보고 -)

  • Kim, Seong-Tae;Lee, Bong-Jin;Park, Woo-Sung;Lee, Sang-Hoon;Kim, Tae-Ho;Lee, Sung-Rak
    • Journal of Korean Orthopaedic Sports Medicine
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    • v.6 no.2
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    • pp.126-129
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    • 2007
  • An irreducible dislocation of the knee joint is quite rare. Most irreducible knee dislocations are posterolateral dislocations and result from the soft tissue interposition. To the best of our knowledge, there is no report of an irreducible knee dislocation result from interposition of the detached cartilage from the medial femoral condyle. We present a case of 51 years old female with irreducible knee dislocation which was treated with an arthroscopic debridement of the detached cartilage, result in reduction of the joint, which is failed in closed reduction. And then we perform the delayed arthroscopic reconstructions for the ruptured anterior and posterior cruciate ligaments. Debridement of the interposed structure using the arthroscope allows for reduction of the joint and good result without the need for an open procedure.

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Microstructural engineering of dual phase steel to aid in bake hardening

  • Banerjee, M.K.
    • Advances in materials Research
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    • v.4 no.1
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    • pp.1-12
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    • 2015
  • Low carbon steel of composition 0.05C - 0.18 Mn - 0.012 Si is intercritically annealed at temperatures $750^{\circ}C$, $775^{\circ}C$ and $800^{\circ}C$. The equilibrated alloys of different amounts of austenite with varying carbon contents are quenched in iced water. The same alloys are subcritically annealed at $675^{\circ}C$ and $700^{\circ}C$ for varying periods of times; the subcritically annealed alloy samples are quenched in iced water. Optical, scanning electron and transmission electron microscopy are carried out for all the samples. The dislocation structure, its distribution and density present in the above prepared duplex ferrite martensite steels are studied. The martensites are found to be highly dislocated due to lattice invariant deformation. At the same time ferrite adjoining the martensite areas also exhibits quite a high dislocation density. The high dislocation density is favorable for strain ageing and hence bakes hardenability. EDS analyses were carried out for both martensite and ferrite phases; it is found that the degree of supersaturation in ferrite together with carbon content in martensite varies with the process parameters. The microhardness test results show that the hardness values of different phases differ appreciably with process parameters. The microstructures and the corresponding microanalyses reveal that differently processed steels contain phases of varying compositions and different distribution.

The Effects of Family Structure and Socialization Influences on Compulsive Buying: A Life Course Study in Thailand (가족구조와 사회화가 강박구매에 미치는 영향에 관한 연구: 태국의 인생행로연구를 중심으로)

  • Nguyen, Hung Vu;Moschis, George P.;Shannon, Randall;Gotthelf, Kristian
    • Journal of Global Scholars of Marketing Science
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    • v.19 no.2
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    • pp.27-39
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    • 2009
  • Compulsive consumption is regarded as a global phenomenon that can adversely affect consumer well-being. Although the topic has been studied in different cultural settings, we have seen relatively little theory development and explanations of compulsive behavior Nearly all previous empirical studies attempt to explain this behavior by correlating measures of compulsive behavior with independent variables taken within the same time frame. However, recent developments in social sciences suggest that such a phenomenon may best understood in the context of the person's earlier-in-life experiences. Using the life course paradigm as an overarching framework, the present research extends previous work on this topic. Following hypotheses were drawn from literature review: H1: The earlier in childhood and adolescence a person experiences family dislocation, the greater his or her likelihood of exhibiting compulsive behaviors in adulthood. H2: The earlier in life the young person experienced family dislocation, the greater the number of family disruption events the young person experienced prior entering adulthood years. H3: Family dislocation leads to (a) increased frequency of socio.oriented family communications and (b) decreased frequency of concept-oriented family communication. H4: Young adults who were raised in families characterized by a strong socio-oriented communication structure are more likely to exhibit compulsive consumption tendencies than those who were raised in families characterized by a weak socio-oriented family communication structure. H5: Young adults who were raised in families characterized by a strong concept-oriented communication structure are less likely to exhibit compulsive consumption tendencies than those who were raised in families characterized by a week concept-oriented family communication structure. H6: The relationship between family disruption events experienced during adolescence and perceived stressfulness of these events is moderated by (a) global family support, (b) emotional family support, and (c) material family support. Those reporting higher levels of family support as teenagers are less likely to report experiencing stress due to family disruption events. H7: Perceived stressfulness of family disruption events experienced during adolescent years are associated with compulsive consumption tendencies in early adulthood. H8: The greater the number of family disruption events young adults experienced during their adolescent years the more frequent was their communication about consumption with their peers. H9: The more frequent was the young persons' communication with their peers about consumption during their adolescent years, the more likely they are to report compulsive buying tendencies as young adults. We use a sample of 120 Thai undergraduate students attending classes taught in English as part of a four-year international program. Product-moment correlations, hierarchical regression analysis and partial correlation were used to analyze data. Results of testing hypotheses showed that hypothesis 2, 4, 7 and 9 were supported and hypothesis 1, 3, 5, 6 and 8 were not supported. Our study did not find a significant relationship between the age when a person experienced family dislocation and their compulsive behavior tendencies expressed as young adults. We did not find a significant relationship between family dislocation and family communication structures. But we found a significant positive relationship between socio-oriented communication structure and compulsive buying and a significant relationship between our peer communication and compulsive buying measures. Also we found perceived stressfulness due to the disruptive events to have a significant positive relationship between the perceived stressfulness and compulsive buying. Implications from these findings, limitations of this research and future research suggestions were discussed.

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Structural, Optical and Photoconductive Properties of Chemically Deposited Nanocrystalline CdS Thin Films

  • Park, Wug-Dong
    • Transactions on Electrical and Electronic Materials
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    • v.12 no.4
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    • pp.164-168
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    • 2011
  • Nanocrystalline cadmium sulphide (CdS) thin films were prepared using chemical bath deposition (CBD), and the structural, optical and photoconductive properties were investigated. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size, dislocation density and lattice constant of CBD CdS thin films were investigated. The dislocation density of CdS thin films initially decreases with increasing film thickness, and it is nearly constant over the thickness of 2,500 ${\AA}$. The dislocation density decreases with increasing the crystallite size. The Urbach energies of CdS thin films are obtained by fitting the optical absorption coefficient. The optical band gap of CdS thin films increases and finally saturates with increasing the lattice constant. The Urbach energy and optical band gap of the 2,900 A-thick CdS thin film prepared for 60 minutes are 0.24 eV and 2.83 eV, respectively. The activation energies of the 2,900 ${\AA}$-thick CdS thin film at low and high temperature regions were 14 meV and 31 meV, respectively. It is considered that these activation energies correspond to donor levels associated with shallow traps or surface states of CdS thin film. Also, the value of ${\gamma}$ was obtained from the light transfer characteristic of CdS thin film. The value of ${\gamma}$ for the 2,900 A-thick CdS thin film was 1 at 10 V, and it saturates with increasing the applied voltage.

A Study of Verb-Second Phenomena in Medieval Spanish Complex Sentences

  • Cho Eun-Young
    • Language and Information
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    • v.9 no.2
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    • pp.85-105
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    • 2005
  • This study aims at investigating the 'verb-second' phenomena indicated in complex sentences of medieval Spanish. Especially, when the complex sentence is composed of a preposed adverbial clause and its succeeding main clause, the subject inversion is noticeable in the latter. The fundamental motive of this type of inversion is due to the 'verb-second' structure, in which a topic appears in the first position and the verb immediately after the topic. So it can be said that the subject inversion is a prerequisite for a verb to be located in the second position when the adverbial clause functions as a topic to the main clause, as is often the case with Germanic languages like German, Dutch, etc.. On the contrary, modern Spanish complex sentences do not show this phenomenon, with a strong tendency to locate a grammatical subject in the preverbal position. Therefore, medieval Spanish might be typologically closer to Germanic languages than to modern Spanish. In order to argue for this assumption, the formal and functional criteria by which the preposed adverbial clause could be defined as a topic NP will be examined across the comparition with left-dislocation structure.

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Shelley's Politics of Discourse (셸리와 담론정치 -『개혁에 대한 철학적 고찰』을 중심으로)

  • Ryu, Son-Moo
    • Journal of English Language & Literature
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    • v.56 no.2
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    • pp.255-276
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    • 2010
  • Despite some critics' efforts to highlight Shelley's political fruitfulness, they tend to disregard meaningful differences that Shelley has from other Jacobin radicals of his times. Accordingly, the critics tackle his apparent incoherence revealed in A Philosophical View of Reform; the first two sections contain a keen insight into the socio-political injustice prevalent in Britain and the reasons behind it, while the third section withdraws from the previous radical position and settles with a moderate electorate reform. This paper argues that recent developments in post-structuralist and post-Marxist theory help to clearly assess Shelley's political position. Emphasizing that the Jacobin concept of revolution is incompatible with the plurality and opening which a radical democracy requires, post-marxists such as Ernest Laclau and Chantal Mouffee claim that a more viable form of political resistance is to expose repression and force involved in hegemonic articulations. For them, dislocation, a distabilization of a discourse that results from the emergence of events which cannot be domesticated, symbolized, or integrated within the discourse, opens up the possibility of freedom for agents. A Philosophical View of Reform is an attempt to dislocate the discourses of monarchy and paper money by exposing their social and historical constructiveness and their repressive exclusion of alternative discourses. The political goal of this essay is to awaken subjects within a hegemonic structure by decentering the structure and to make them act by stimulating new discoursive constructions.