• Title, Summary, Keyword: Back Analysis

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Pain Patterns and Factors Affecting of Low Back Pain in Middle-aged Women (중년여성이 경험하는 만성요통의 통증양상 및 영향요인)

  • Ham, Young-Lim;Seo, Bok-Nam;Ahn, Yang-Heui
    • Journal of muscle and joint health
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    • v.14 no.1
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    • pp.33-41
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    • 2007
  • Purpose: The purpose of the study was to identify the pain patterns and factors affecting low back pain in middle-aged women with backache. Method: A descriptive research design was utilized. The participants were middle-aged women who visited to two back pain clinics in Wonju from October, 2006 through February, 2007. A total of 195 low back pain patients agreed to participate in this study, and data from 177 were analyzed. Data were collected using a questionnaire which included a modified short-form Korean pain rating scale, demographic factors, factors related to low back pain and health behavior. Descriptive statistics and multiple regression analysis was utilized in the analysis. Results: The mean score for low back pain was relatively low(M=21.57, SD=11.44). Among pain patterns, scores for dull pain were the highest of all the dimensions. In the regression analysis, significant factors affecting low back pain were found to be age, level of education, religion, BMI, experience of pregnancy, delivery type and exercise. These variables explained 24.8% of variance in low back pain(F=3.79, p<.001). Conclusion: These results suggest that nurses need for assessment and intervention to take into consideration pain patterns as well as factors affecting middle-age women with backache.

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Estimation of Tension Forces of Assembly Stay Cables Connected with Massive Anchorage Block (중량 앵커리지 블록과 연결된 조립 스테이 케이블의 장력 추정)

  • Jeong, Woon;Kim, Nam-Sik
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.435-440
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    • 2004
  • In this paper, the tension of assembly stay cable connected with massive anchorage block was calculated through back analysis of in-situ frequencies measured from a stadium structure. Direct approach to back analysis is adopted using the univariate method among the direct search methods as an optimization technique. The univariate method can search the optimal tension without regard to the initial ones and has a rapid convergence rate. To verify the reliability of back analysis, Tension formulas proposed by Zui et al. and Shimada were used. Tensions estimated by three methods are compared with the design tension, and are in a reasonable agreement with an error of more or less than 15%. Therefore, it is shown that back analysis applied in this paper is appropriate for estimation of cable tension force.

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A Study on Back EMF of BLDC Motor Using Numetical Analysis Method (수치해석 방법을적용한 BLDC 전동기의 역기전력 연구)

  • Kim, Hyun-Cheol
    • Journal of the Korean Society of Safety
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    • v.23 no.4
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    • pp.36-41
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    • 2008
  • This report describes the analytical solution of back EMF for BLDC motor using numerical analysis of air gap flux density. The analysis of air gap flux density is the key to expect the performance of back EMF for the design of brushless motor. The numerical analysis and FEM analysis are performed to vary attachment of stator side or rotor side, radial flux magnetization or parallel flux magnetization, magnet arc angle in the condition of constant air gap. This results have more reliable data comparing with test result of the back EMF for 7 phase BLDC motor.

A Study on the Behavior Prediction of Underground Structures by Back Analysis (역해석에 의한 지하구조체의 거동예측에 관한 연구)

  • 장정범;김문겸
    • Tunnel and Underground Space
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    • v.8 no.2
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    • pp.139-145
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    • 1998
  • The reliable estimation of the system parameters and the accurate prediction of the system behavior are important to design underground structures safely and economically. Especially, the elastic modulus and the in-situ stresses are very important parameters in predicting the behavior of the underground structure. Therefore, the back analysis using the field measurement data is developed to determine accurately the elastic modulus and the in-situ stresses of the underground structural system in this study. A back analysis using the combined finite and boundary element is developed. It can consider the far field boundary condition and is efficient in computation. In this study, a back analysis is performed to predict behaviors of underground structures for the real construction site. The comparison between the results of the back analysis with field measurement data and the obtained material properties from the field test shows good agreement for the real construction site.

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Estimation of Tension Forces of Assembly Stay Cables Connected with Massive Anchorage Block (중량 앵커리지 블록과 연결된 조립 스테이 케이블의 장력 추정)

  • Jeong, Woon;Kim, Nam-Sik
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.3
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    • pp.346-353
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    • 2005
  • In this paper, the tension of assembly stay cable connected with massive anchorage block was calculated through back analysis of in-situ frequencies measured from a stadium structure. Direct approach to back analysis is adopted using the univariate method among the direct search methods as an optimization technique. The univariate method can search the optimal tension without regard to the initial ones and has a rapid convergence rate. To verify the reliability of back analysis, Tension formulas proposed by Zui et al. and Shimada were used. Tensions estimated by three methods are compared with the design tension, and are in a reasonable agreement with an error of more or less than 15%. Therefore, it is shown that back analysis applied in this paper is appropriate for estimation of cable tension force.

DEA optimization for operating tunnel back analysis (운영 중 터널 역해석을 위한 차분진화 알고리즘 최적화)

  • An, Joon-Sang;Kim, Byung-Chan;Moon, Hyun-Koo;Song, Ki-Il;Su, Guo-Shao
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.2
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    • pp.183-193
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    • 2016
  • Estimation of the stability of an operating tunnel through a back analysis is a difficult concept to analyze. Specially, when a relatively thick lining is constructed as in case of a subsea tunnel, there will be a limit to the use of displacement-based tunnel back analysis because the corresponding displacement is too small. In this study, DEA is adopted for tunnel back analysis and the feasibility of DEA for back analysis is evaluated. It is implemented in the finite difference code FLAC3D using its built-in FISH language. In addition, the stability of a tunnel lining will be evaluated from the development of displacement-based algorithm and its expanded algorithm with conformity of several parameters such as stress measurements.

Developement of back-analysis model for determining the mechanical properties of jointed rock (절리암반의 역학적 특성 분석을 위한 역해석 모델 개발)

  • Cho, Tae-Chin
    • Tunnel and Underground Space
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    • v.6 no.1
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    • pp.19-29
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    • 1996
  • Back analysis model, capable of calculating the mechanical properties and the in-situ stresses of jointed rock mass, was developed based on the inverse method using a continuum theory. Constitutive equation for the behavior of jointed rock contains two unknown parameters, elastic modulus of intact rock and stiffness of joint, hence algorithm which determines both parameters simultaneously cannot be established. To avoid algebraic difficulties elastic modulus of intact rock was assumed to be known, since the representative value of which would be quite easily determined. Then, the ratio ($\beta$) of joint stiffness to elastic modulus of intact rock was assigned and back analysis for the behavior of jointed rock was carried-out. The value $\beta$ was repeatedly modified until the elastic modulus from back analysis became very comparable to the predetermined value. The joint stiffness could be calculated by multipling the ratio $\beta$ to the final result of elastic modulus. Accuracy and reliability of back analysis procedure was successfully testified using a sample model simulating the underground opening in the jointed rock mass. Applicability of back analysis model for the underground excavation in practice was also verified by analyzing the mechanical properties of jointed rock in which underground oil storage cavern were under construction.

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Upper Back Somatotype Analysis for Development of Hanbok Jeogori Pattern of Female in Late 20s (20대 후반 성인 여성의 한복 저고리 패턴 개발을 위한 상반신 뒷면의 체형 분석)

  • Eom, Ran-I;Lee, Yejin
    • Korean Journal of Human Ecology
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    • v.23 no.5
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    • pp.891-904
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    • 2014
  • The objective of this study is to classify somatotypes of back-surface shape of women in their late 20s by using 3D body scan data(Size Korea 2010) in order to improve fitness of Hanbok Jeogori. The results were as follows: 1. According to the in-depth survey of the experienced expert's interview, most problems related to the fit were caused by the back area of Jeogori. 2. The result of factor analysis indicated that 6 factors were extracted and those factors comprised 82.85% of total variance. 3. According to the cluster analysis, back somatotypes of women in their late 20s were categorized by two types : straight type(54.1%) and bending type(46.9%). The results could be used as the Hanbok Jeogori to improve the fitness of back-surface shape.

Prevalence of Low Back Symptom and Impact of Job Stress among Working Women as Clinical Nurses in University Hospitals

  • Lee, Kyung-Jae;Kim, Joo-Ja;Kim, Jeung-Im
    • Korean Journal of Women Health Nursing
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    • v.17 no.5
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    • pp.484-490
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    • 2011
  • Purpose: This study was aimed to investigate the impact of job stress on low back symptoms among Clinical nurses (CNs) in university hospital. Methods: A total of 322 CNs employed in a hospital in Seoul were interviewed by a well-trained interviewer using the structured questionnaire. Data collected for this study includes demographics, social and work characteristics, low back symptoms, and job stress. To test the impact of job stress on low back symptoms, we used multiple logistic regression analysis. Results: The prevalence of low back symptoms was 25.8% in this study. Low back symptoms differed significantly by factors, such as physical work burden, past history of injury and work duration. Also low back symptoms differed significantly by organizational system among independent variables of job stress. In a multiple logistic regression analysis, the odds ratio of organizational system to low back symptoms was 2.07 after an adjustment. Conclusion: This study showed that organizational system among job stress was a significant variable in explaining low back symptoms. We suggest the improvement of organizational system category as a preventive strategy for low back pain in CNs working in hospital.

Spin-up, Spring-back Load Analysis of KC-100 Nose Landing Gear using Explicit Finite Element Method (외연적 유한요소법을 이용한 KC-100 전방착륙장치 Spin-up, Spring-back 하중 해석)

  • Park, Ill-Kyung;Kim, Sung-Jun;Ahn, Seok-Min
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.19 no.4
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    • pp.51-57
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    • 2011
  • The spin-up and the spring-back are most severe load cases in the aircraft landing gear design. These load cases are caused by reciprocal action of complex physical phenomenon such as the friction between a tire and ground, inertia of the rotation of a tire and the flexibility of a landing gear structure. Generally, the empirical formula or the theoretical formula is used to calculate the spin-up and spring-back load in the early stage of the development program of the aircraft landing gear. After the materialization of the design of a landing gear, spin-up and spring-back load are acquired by the free drop test. In this study, the spin-up and the spring-back load of the rubber shock absorber type KC-100 nose landing gear are calculated by the explicit finite element analysis. Through this analysis, more accurate and realistic spin-up and spring back loads could be applied to the early phase of the development of the aircraft landing gear.