• Title/Summary/Keyword: Plastic analysis

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Finite Element Analysis of Elasto-Plastic Large Deformation considering the Isotropic Damage(the 2nd Report) (등방성손상을 고려한 탄소성 대변형 무제의 유한요소해석(제2보))

  • 이종원
    • Journal of Ocean Engineering and Technology
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    • v.14 no.2
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    • pp.76-83
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    • 2000
  • this paper was concentrated on the finite element formulation to solve boundary value problems by using the isotropic elasto-plastic damage constitutive model proposed previously(Noh, 2000) The plastic damage of ductile materials is generally accompanied by large plasticdeformation and strain. So nonlinearity problems induced by large deformation large rotation and large strain behaviors were dealt with using the nonlinear kinematics of elasto-plastic deformations based on the continuum mechanics. The elasto-plastic damage constitutive model was applied to the nonlinear finite element formulation process of Shin et al(1997) and an improved analysis model considering the all nonlinearities of structural behaviors is proposed. Finally to investigate the applicability and validity of the numerical model some numerial examples were considered.

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Predictors of Readmission after Inpatient Plastic Surgery

  • Jain, Umang;Salgado, Christopher;Mioton, Lauren;Rambachan, Aksharananda;Kim, John Y.S.
    • Archives of Plastic Surgery
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    • v.41 no.2
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    • pp.116-121
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    • 2014
  • Background Understanding risk factors that increase readmission rates may help enhance patient education and set system-wide expectations. We aimed to provide benchmark data on causes and predictors of readmission following inpatient plastic surgery. Methods The 2011 National Surgical Quality Improvement Program dataset was reviewed for patients with both "Plastics" as their recorded surgical specialty and inpatient status. Readmission was tracked through the "Unplanned Readmission" variable. Patient characteristics and outcomes were compared using chi-squared analysis and Student's t-tests for categorical and continuous variables, respectively. Multivariate regression analysis was used for identifying predictors of readmission. Results A total of 3,671 inpatient plastic surgery patients were included. The unplanned readmission rate was 7.11%. Multivariate regression analysis revealed a history of chronic obstructive pulmonary disease (COPD) (odds ratio [OR], 2.01; confidence interval [CI], 1.12- 3.60; P=0.020), previous percutaneous coronary intervention (PCI) (OR, 2.69; CI, 1.21-5.97; P=0.015), hypertension requiring medication (OR, 1.65; CI, 1.22-2.24; P<0.001), bleeding disorders (OR, 1.70; CI, 1.01-2.87; P=0.046), American Society of Anesthesiologists (ASA) class 3 or 4 (OR, 1.57; CI, 1.15-2.15; P=0.004), and obesity (body mass index ${\geq}30$) (OR, 1.43; CI, 1.09-1.88, P=0.011) to be significant predictors of readmission. Conclusions Inpatient plastic surgery has an associated 7.11% unplanned readmission rate. History of COPD, previous PCI, hypertension, ASA class 3 or 4, bleeding disorders, and obesity all proved to be significant risk factors for readmission. These findings will help to benchmark inpatient readmission rates and manage patient and hospital system expectations.

Contemporary Koreans' Perceptions of Facial Beauty

  • Rhee, Seung Chul;An, Soo-Jung;Hwang, Rahil
    • Archives of Plastic Surgery
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    • v.44 no.5
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    • pp.390-399
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    • 2017
  • Background This article aims to investigate current perceptions of beauty of the general public and physicians without a specialization in plastic surgery performing aesthetic procedures. Methods A cross-sectional and interviewing questionnaire was administered to 290 people in Seoul, South Korea in September 2015. The questionnaire addressed three issues: general attitudes about plastic surgery (Q1), perception of and preferences regarding Korean female celebrities' facial attractiveness (Q2), and the relative influence of each facial aesthetic subunit on overall facial attractiveness. The survey's results were gathered by a professional research agency and classified according to a respondent's gender, age, and job type ($95%{\pm}5.75%$ confidence interval). Statistical analysis was performed using SPSS ver. 10.1, calculating one-way analysis of variance with post hoc analysis and Tukey's t-test. Results Among the respondents, 38.3% were in favor of aesthetic plastic surgery. The most common source of plastic surgery information was the internet (50.0%). The most powerful factor influencing hospital or clinic selection was the postoperative surgical results of acquaintances (74.9%). We created a composite face of an attractive Korean female, representing the current facial configuration considered appealing to the Koreans. Beauty perceptions differed to some degree based on gender and generational differences. We found that there were certain differences in beauty perceptions between general physicians who perform aesthetic procedures and the general public. Conclusions Our study results provide aesthetic plastic surgeons with detailed information about contemporary Korean people's attitudes toward and perceptions of plastic surgery and the specific characteristics of female Korean faces currently considered attractive, plus trends in these perceptions, which should inform plastic surgeons within their specialized fields.

Methodology of Three-Dimensional Thermoforming Analysis to Simulate Forming Process of Medium and Large-Sized Plastic Parts (중대형 플라스틱 제품 성형공정 모사를 위한 3 차원 진공 열성형 해석 기법)

  • Lee, Ho Jin;Ahn, Dong Gyu
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.11
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    • pp.953-960
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    • 2015
  • The thermoforming process has been widely used to manufacture medium- and large-sized plastic parts because of the relatively low cost and high productivity, as compared with other plastic forming processes. One of current salient issues of thermoforming industries is the reduction of trial and error during the production of the thermoformed product. Hence, there is a significant increasing interest in the thermoforming analysis by the thermoforming industries. The goal of this paper is to investigate a methodology of the three-dimensional thermoforming analysis for medium- and large-sized plastic parts. There is a discussion about methodologies of thermoforming analysis, as well as material modeling, and three-dimensional finite element analysis. Furthermore, there is an examination, through case studies, about the applicability of the proposed methodology concerning the thermoforming analysis.

A Study on Preferred Morphologic Feature and Proportion of Facial Aesthetic Subunit by Korean General Public (일반인이 선호하는 얼굴의 미적 단위별 형태와 비율 연구)

  • Yoon, Yong-Il;Lee, Dong-Lark;Yoo, Jung-Seok;Rhee, Seung-Chul;Hur, Gi-Yeun;Kim, Ju-Yeon
    • Archives of Plastic Surgery
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    • v.37 no.4
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    • pp.351-360
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    • 2010
  • Purpose: As the influence of mass media increases, the general standard of attractiveness or beauty of a face also changes. The primary purpose of the study is to find out the factors of the attractive and beautiful face recognized by public. Methods: We picked out standard model photography and operated with Adobe$^{(R)}$ Photoshop$^{(R)}$ and Monariza$^{(R)}$ virtual plastic surgery program. The contour of face, eye, nose, forehead, zygoma, chin and proportion of upper, middle, lower face were changed. The interview survey was conducted through structured standard photo for 310 respondents. That was utilized in the final analysis. Multiple regression analysis was executed by SPSS 12.0. It was used to deal with statistical data and all the other necessary analysis. Results: According to general characteristics of the respondents, many differences were found in preferred face and facial aesthetic subunits. The younger generation preferred the lozenge and inverted triangle shape contour. The respondents over 40 of age preferred the egg shape contour. In chin and zygoma contour, the respondents at the age of 20 preferred distinctly small chin and relatively small lower face. On the other hand, the respondents over 40 of age preferred the wide zygoma relatively. In the proportion of upper, middle, lower face, 51.0% of respondents answered 1 : 1 : 1. If they want to have an aesthetic operation, they preferred protruding forehead. Also they preferred the small chin and V-shaped chin in frontal view. Conclusion: Many respondents preferred to have a plastic surgery for the better facial subunit. The statistical evidence from this study suggests that the harmony and balance of facial aesthetic subunits make attractive and beautiful face.

Definitive Closure of the Tracheoesophageal Puncture Site after Oncologic Laryngectomy: A Systematic Review and Meta-Analysis

  • Escandon, Joseph M.;Mohammad, Arbab;Mathews, Saumya;Bustos, Valeria P.;Santamaria, Eric;Ciudad, Pedro;Chen, Hung-Chi;Langstein, Howard N.;Manrique, Oscar J.
    • Archives of Plastic Surgery
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    • v.49 no.5
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    • pp.617-632
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    • 2022
  • Tracheoesophageal puncture (TEP) and voice prosthesis insertion following laryngectomy may fail to form an adequate seal. When spontaneous closure of the fistula tract does not occur after conservative measures, surgical closure is required. The purpose of this study was to summarize the available evidence on surgical methods for TEP site closure. A comprehensive search across PubMed, Web of Science, SCOPUS, and Cochrane was performed to identify studies describing surgical techniques, outcomes, and complications for TEP closure. We evaluated the rate of unsuccessful TEP closure after surgical management. A meta-analysis with a random-effect method was performed. Thirty-four studies reporting on 144 patients satisfied inclusion criteria. The overall incidence of an unsuccessful TEP surgical closure was 6% (95% confidence interval [CI] 1-13%). Subgroup analysis showed an unsuccessful TEP closure rate for silicone button of 8% (95% CI < 1-43%), 7% (95% CI < 1-34%) for dermal graft interposition, < 1% (95% CI < 1-37%) for radial forearm free flap, < 1% (95% CI < 1-52%) for ligation of the fistula, 17% (95% CI < 1-64%) for interposition of a deltopectoral flap, 9% (95% CI < 1-28%) for primary closure, and 2% (95% CI < 1-20%) for interposition of a sternocleidomastoid muscle flap. Critical assessment of the reconstructive modality should take into consideration previous history of surgery or radiotherapy. Nonirradiated fields and small defects may benefit from fistula excision and tracheal and esophageal multilayer closure. In cases of previous radiotherapy, local flaps or free tissue transfer yield high successful TEP closure rates. Depending on the defect size, sternocleidomastoid muscle flap or fasciocutaneous free flaps are optimal alternatives.

Prediction of Member Plastic Rotation Demands for Earthquake Design of Moment Frames (모멘트골조의 내진설계를 위한 부재 소성변형 요구량 예측)

  • Eom, Tae-Sung;Park, Hong-Gun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.5
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    • pp.51-60
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    • 2009
  • To secure the structural safety of structures and members against earthquakes, the plastic deformation capacity demand of members should be accurately predicted. In the present study, a method for the evaluation of the plastic deformations of members for moment frames was developed. To facilitate the practical use of the proposed method in equivalent seismic design, the plastic deformations of members were evaluated based on the results of elastic analysis, without using nonlinear analysis. The plastic deformation demands of members were formulated as functions of story drift demand, redistributed moment and member stiffness. Story drift demand and moment redistribution were directly determined from elastic analysis. The proposed method was applied to an 8 story-2 bay moment frame, and the predicted plastic deformations were verified using nonlinear analysis. The results showed that the proposed method could be used to accurately predict the member plastic rotations with simple calculations. The proposed method can be applied both to the earthquake design of new structures and to the performance evaluation of existing structures.

Donor-Site Morbidity Analysis of Thenar and Hypothenar Flap

  • Dong Chul Lee;Ho Hyung Lee;Sung Hoon Koh;Jin Soo Kim;Si Young Roh;Kyung Jin Lee
    • Archives of Plastic Surgery
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    • v.51 no.1
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    • pp.94-101
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    • 2024
  • Background For the small glabrous skin defect, Thenar and Hypothenar skin are useful donors and they have been used as a free flap. Because of similar skin characteristics, both flaps have same indications. We will conduct comparative study for the donor morbidity of the Free thenar flap and Hypothenar free flap. Methods From January 2011 to December 2021, demographic data, characteristics of each flap, and complications using retrospective chart review were obtained. Donor outcomes of the patient, who had been followed up for more than 6 months, were measured using photographic analysis and physical examination. General pain was assessed by Numeric Rating Scale (NRS) score, neuropathic pain was assessed by Douleur Neuropathique 4 Questions (DN4) score, scar appearance was assessed by modified Vancouver Scar Scale (mVSS), and patient satisfaction was assessed on a 3-point scale. Statistical analysis was performed on the outcomes. Results Out of the 39 survey respondents, 17 patients received Free thenar flaps, and 22 patients received Hypothenar free flaps. Thenar group had higher NRS, DN4, and mVSS (p < 0.05). The average scores for the Thenar and Hypothenar groups were 1.35 and 0.27 for NRS, 2.41 and 0.55 for DN4, and 3.12 and 1.59 for mVSS, respectively. Despite the Hypothenar group showing greater satisfaction on the 3-point scale (1.82) compared with the Thenar group (1.47), the difference was not significant (p = 0.085). Linear regression analysis indicated that flap width did not have a notable impact on the outcome measures, and multiple linear regression analysis revealed no significant interaction between flap width and each of the outcome measures. Conclusion Despite the limited number of participants, higher donor morbidity in general pain, neuropathic pain, and scar formation was noted in the Thenar free flap compared with the Hypothenar free flap. However, no difference in overall patient satisfaction was found between the two groups.

Assessment of Fatigue Crack Propagation Considering the Redistribution of Residual Stress due to Overload

  • Jang, Chang-Doo;Leem, Hyo-Kwan;Choi, Yeoung-Dal;Bang, Jun-Kee;So, Ha-Young
    • Journal of Ship and Ocean Technology
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    • v.11 no.2
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    • pp.26-33
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    • 2007
  • For the assessment of the retardation of fatigue crack propagation behavior due to overload, new FE analysis algorithms considering compressive residual stress redistribution near crack tip was proposed in this paper. The size of plastic zone near crack tip was obtained by elasto-plastic analysis and it was compared with Irwin's equation. The amount of residual stress redistribution was assessed by subsequent elasto-plastic analysis, and the difference of residual stress distributions between constant amplitude load and overload was obtained. In the analysis of fatigue crack propagation, the applied SIF range was evaluated by ASTM E647, and the effect of residual stresses on crack propagation was considered using the effective SIF concept. The test results of crack propagations were compared with the predicted data obtained by the analysis.