• 제목/요약/키워드: plastic

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Determination of earthquake safety of RC frame structures using an energy-based approach

  • Merter, Onur;Ucar, Taner;Duzgun, Mustafa
    • Computers and Concrete
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    • 제19권6호
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    • pp.689-699
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    • 2017
  • An energy-based approach for determining earthquake safety of reinforced concrete frame structures is presented. The developed approach is based on comparison of plastic energy capacities of the structures with plastic energy demands obtained for selected earthquake records. Plastic energy capacities of the selected reinforced concrete frames are determined graphically by analyzing plastic hinge regions with the developed equations. Seven earthquake records are chosen to perform the nonlinear time history analyses. Earthquake plastic energy demands are determined from nonlinear time history analyses and hysteretic behavior of earthquakes is converted to monotonic behavior by using nonlinear moment-rotation relations of plastic hinges and plastic axial deformations in columns. Earthquake safety of selected reinforced concrete frames is assessed by using plastic energy capacity graphs and earthquake plastic energy demands. The plastic energy dissipation capacities of the frame structures are examined whether these capacities can withstand the plastic energy demands for selected earthquakes or not. The displacements correspond to the mean plastic energy demands are obtained quite close to the displacements determined by using the procedures given in different seismic design codes.

Bounds on plastic strains for elastic plastic structures in plastic shakedown conditions

  • Giambanco, Francesco;Palizzolo, Luigi;Caffarelli, Alessandra
    • Structural Engineering and Mechanics
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    • 제25권1호
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    • pp.107-126
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    • 2007
  • The problem related to the computation of bounds on plastic deformations for structures in plastic shakedown condition (alternating plasticity) is studied. In particular, reference is made to structures discretized by finite elements constituted by elastic perfectly plastic material and subjected to a special combination of fixed and cyclic loads. The load history is known during the steady-state phase, but it is unknown during the previous transient phase; so, as a consequence, it is not possible to know the complete elastic plastic structural response. The interest is therefore focused on the computation of bounds on suitable measures of the plastic strain which characterizes just the first transient phase of the structural response, whatever the real load history is applied. A suitable structural model is introduced, useful to describe the elastic plastic behaviour of the structure in the relevant shakedown conditions. A special bounding theorem based on a perturbation method is proposed and proved. Such theorem allows us to compute bounds on any chosen measure of the relevant plastic deformation occurring at the end of the transient phase for the structure in plastic shakedown; it represents a generalization of analogous bounding theorems related to the elastic shakedown. Some numerical applications devoted to a plane steel structure are effected and discussed.

2차원 평면응력 상태에서 되풀이 소성역이 피로균열 열림 현상에 미치는 영향에 관한 연구 (An Evaluation on the Effect of Reversed Plastic Zone on the Fatigue Crack Opening Behavior under 2-D Plane Stress)

  • 최현창
    • 대한기계학회논문집A
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    • 제29권8호
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    • pp.1078-1084
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    • 2005
  • The relationship between fatigue crack opening behavior and the reversed plastic zone sizes is studied. An elastic-plastic finite element analysis (FEA) is performed to examine the opening behavior of fatigue crack, where the contact elements are used in the mesh of the track tip area. The smaller element size than reversed plastic zone size is used fer evaluating the distribution of reversed plastic zone. In the author's previous results the FEA could predict the crack opening level, which crack tip elements were in proportion to the theoretical reversed plastic zone size. It is found that the calculated reversed plastic zone size is related to the theoretical reversed plastic zone size and crack opening level. The calculated reversed plastic zone sizes are almost equal to the reversed plastic zone considering crack opening level obtained by experimental results. It can be possible to predict the crack opening level from the reversed plastic zone size calculated by finite element method. We find that the experimental crack opening levels correspond with the opening values of contact nodes on the calculated reversed plastic zone of finite element simulation.

한국 영화와 드라마에 나타난 성형외과 의사와 성형수술의 이미지 (Image of Plastic Surgeons and Plastic Surgery Illustrated in Korean Movies and TV Dramas)

  • 김한준;황건
    • 대한두개안면성형외과학회지
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    • 제13권2호
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    • pp.95-98
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    • 2012
  • Nowadays, plastic surgical operations are increasingly being performed in Korea. We have gained added interest in this because some professional pictures contain plastic surgery in their venue. In the films, we intend to see the recognition of society for plastic surgeons and which field of plastic surgery. The list of movies for analysis were 'Plastic Beauty (1975)', 'Penthouse Elephant (2005)', '200 Pounds Beauty (2006)', 'Cinderella (2006)', and 'Time (2006)'. The TV dramas were 'She is looking (2005)', 'Lovers (2006-2007)', and 'Before & After Plastic Surgery Clinic (2008)'. Films were analyzed according to the following: the chief complaints and names of the operations, character of plastic surgeons, result of the operation and its possibility in reality, and its effect of plastic surgery on the life of the patients. Most of the film contained facial transplantation or the change of the face or body different from the original shape. Character type of the plastic surgeons was mostly medical realism, rather than ideal humanism. Most of the plastic surgeons have capability as a doctor; however, some of them had extramarital affairs. The surgery was successful in most of the cases, but were the patients happy with the results? This was not the case in the movies. In only one movie, '200 Pounds Beauty', the patient became happy; rest of them were eminently unhappy with the outcome. Why the discrepancy? It is difficult to analyze the minds of the people in the films, but considering that the majority of the characters in the films were rather unsavory, one may deduce that a crooked mind functions differently. Perhaps it is too much to hope for a day that will come when we will see a film that portrays the mental anguish that accompanies each and every procedure the Korean plastic surgeons make.

한국 성형외과학술지의 영향력지수 및 발간기간 (Impact Factors and Publication Times of Korean Plastic Surgery Journals)

  • 황건;최혁규
    • Archives of Plastic Surgery
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    • 제35권2호
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    • pp.147-151
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    • 2008
  • Purpose: The purposes of the authors' analysis were to assess the values that plastic surgery journals demonstrate in terms of the standardized measures created by the Korea Medical Citation Index, and to assess the relationship between these values and the turnaround time of these journals. Methods: The overall indexes of J Korean Soc Plast Reconstr Surg(JKSPRS), J Korean Soc Aesthetic Plast Surg(JKSAPS), J Korean Cleft Palate-Craniofac Assoc (JKCPRA) were compared with those of journals related with Korean plastic surgery using the following parameters: impact factor, cited half-life, total articles, and the number of journals. Korean plastic surgery journals were compared with journals from relative fields. In addition, an evaluation of all original articles published in 2007, assessing the time intervals from submission to publication was conducted for Korean plastic surgery journals and various journals which were related with plastic surgery. Results: The number of articles for Korean plastic surgery journals for 2006 ranged from 19 for JKCPRA to 149 for JKSPRS. The time interval from submission to publication of an article among Korean plastic surgery journals for 2007 ranged from 73.7 days for JKSAPS to 176.2 days for JKSPRS. The variation in impact factor of JKSPRS for the period from 2002 to 2005 increased from 0.084 in the year 2002 to 0.168 in 2005. But the impact factor in 2006 has fallen to 0.112. Conclusion: JKSPRS demonstrated comparatively high overall index values and a short turnaround time in comparison to relative journals. To improve the status of Korean plastic surgery journals, members of Korean plastic surgeons should quate Korean plastic surgery journals and adjust key word to MeSH. The title written down in Korean should use medical terminology published by Korean medical association.

Plastic Surgeons as Medical Directors: A Natural Transition into Medical Leadership

  • Jalalabadi, Faryan;Ferry, Andrew M.;Chang, Andrew;Reece, Edward M.;Izaddoost, Shayan A.;Hassid, Victor J.;Tahiri, Youssef;Buchanan, Edward P.;Winocour, Sebastian J.
    • Archives of Plastic Surgery
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    • 제49권2호
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    • pp.221-226
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    • 2022
  • With the growing complexity of the U.S. health care system, highly motivated medical directors with strong leadership skills are vital to the success of health care facilities. Presently, there are no articles assessing a plastic surgeon's qualifications for the role of medical director. In addition, there is a paucity of literature comparing the responsibilities of medical directors across various types of health care institutions. Herein, we outline why plastic surgeons have the unique skillset to succeed in this role and highlight the differences between medical director positions across the vast landscape of health care. While the intricacies of this position vary greatly across different landscapes of the health care industry, successful medical directors lead by following a set of universal principles predisposing them for success. Plastic surgeons innately exhibit a subset of particular traits deeming them suitable candidates for the medical director position. While transitioning from the role of a surgeon to that of a medical director does require some show of adaptation, plastic surgeons are ultimately highly likely to find intrinsic benefit from serving as a medical director.