• 제목/요약/키워드: Back Analysis

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확장 Baysian 방법과 상대변위를 이용한 터널 역해석 기법의 적용사례연구 (A Case Study of Back-analysis Technique in Tunnelling Using Extended Bayesian Method and Relative Convergence Measurement)

  • 이인모;최민광;조국환;이근하;최충식
    • 한국지반공학회논문집
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    • 제21권3호
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    • pp.109-118
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    • 2005
  • 터널과 같은 선형 구조물의 경우, 터널이 시공될 지반의 전체적인 상태를 설계단계에서 정확히 파악하기는 매우 힘든 것이 사실이다. 따라서 시공과정에서 획득되어지는 계측자료와 설계단계에의 사전정보를 적절히 조합하는 피드백(feed-back)과정이 필수적이게 된다. 본 논문에서는 터널 내에서 계측된 상대변위만을 역해석 입력값으로 적용한 3차원 터널 역해석 기법을 이용하여 터널 주변 지반의 최적의 지반정수를 평가하였다. 이를 위하여 예측치와 계측치를 합리적으로 조합할 수 있는 확장 Bayesian 방법(Extended Bayesian Meoth EBM)을 역해석의 목적함수로 사용하였으며, 터널 내공변위 예측을 위해 3차원 수치해석을 적용하였다. 두 곳의 실제 터널 현장계측자료를 바탕으로 역해석을 수행하였으며, 이를 통하여 제안된 역해석 기법의 효용성을 검증하였다.

High Heel이 허리 근육 피로에 미치는 영향에 관한 연구 (The effects of high hell on back muscle fatigue)

  • 현수돈;김정룡
    • 대한인간공학회지
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    • 제16권3호
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    • pp.37-48
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    • 1997
  • It is very common for women wear shoes with a high heel. It has been known that the high heel could disfigure the foot shape and cause various joint problems including back pain. However, few quantitative studies have been conducted. Therefore, in this study, the low back muscle has been investigated in order to find fatifue effect due to different heights of the heel. In particular, 0, 4, 6 and 8cm heel and two different shapes of heel have been used for an experiment. Ten healthy female subjects volunteered for the study. Isometric Trunk Exertion Frame(ITEF) and Electromyography were used to measure tha Median Frequency via Spectral analysis. The results indicated that the heel height significantly affected the local muscle fatigue of the back. After post hoc analysis, it was found that a proper heel height ougth to be lower than 5cm not to have severely fatigued back muscle after a casual walk for an hour. Such results could be applies to female industrial workers in order to prevent a cumulative trauma disorder of the back, and also to design a female dress shoes minimizing low back fatigue.

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Theoretical and Experimental Analysis of Back-Gated SOI MOSFETs and Back-Floating NVRAMs

  • Avci, Uygar;Kumar, Arvind;Tiwari, Sandip
    • JSTS:Journal of Semiconductor Technology and Science
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    • 제4권1호
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    • pp.18-26
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    • 2004
  • Back-gated silicon-on-insulator MOSFET -a threshold-voltage adjustable device-employs a constant back-gate potential to terminate source-drain electric fields and to provide carrier confinement in the channel. This suppresses shortchannel effects of nano-scale and of high drain biases, while allowing a means to threshold voltage control. We report here a theoretical analysis of this geometry to identify its natural length scales, and correlate the theoretical results with experimental device measurements. We also analyze experimental electrical characteristics for misaligned back-gate geometries to evaluate the influence on transport behavior from the device electrostatics due to the structure and position of the back-gate. The backgate structure also operates as a floating-gate nonvolatile memory (NVRAM) when the back-gate is floating. We summarize experimental and theoretical results that show the nano-scale scaling advantages of this structure over the traditional front floating-gate NVRAM.

Back Filler의 보강에 따른 STS VOD 래들의 열응력 해석 (Thermal Stress Analysis of STS VOD Ladle according to the reinforcement of back filler)

  • 이순욱;함경춘;배성인;송정일
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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    • pp.310-315
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    • 2000
  • We analyzed thermal stress of the STS VOD ladle by the variation of material property of refractory, and determined the location of back filler using FE analysis. Thermal distribution of refractory of ladle between hot face and back face were decreased by the increasing the thermal conductivity, and thermal stress of refractory were decreased about 2 to 4 times with the decreasing the young's modulus coefficients. Back filler, which is constructed to absorb the thermal expansion of dolomite refractory, has relatively low thermal conductivity. Inner side of refractory of ladle maintained high temperature, but temperature of outer side of ladle decreased low. Consequently, inner expansion and outer contraction were appeared. and thermal stress were increased, so thermal stress by the construction of back filler were increased.

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정보화 시공에서 Feed Back Analysis (터널, 암반사면, 지반굴착 등 Hard Material 사례중심으로) (The Role of Feed Back Analysis in Observational Method)

  • 김학문
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2002년도 가을 학술발표회 논문집
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    • pp.147-179
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    • 2002
  • The important role of observational method in geotechnical engineering are emphasized together with the direction of future development, concerning successful application of the technique on the site investigation, design and feed back at various construction stages. Case histories on the application of feed back are introduced in order to achieve the most economical and reliable construction for tunnel, rock slope and deep excavations through feed back system at design and construction stages. Also the limitations and advantages of the observational method and the role of feed back system are discussed for construction of tunnel, rock slope and deep excavation in hard ground such as layered ground conditions including weathered, soft and hard rocks.

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Back-to-Back옹벽의 거동에 관한 수치 해석적 연구 (Numerical Investigation on Behavior of Back-to-Back Reinforced Earth Wall)

  • 유충식;김재왕
    • 한국지반공학회논문집
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    • 제25권12호
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    • pp.131-142
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    • 2009
  • 보강토 옹벽은 콘트리트 옹벽에 비해 시공성, 경제성, 미관 등이 뛰어나 대체공법으로 각광받고 있으며, 많은 장점들로 인해 일반 옹벽의 대체공법으로서 그 적용성을 인정받고 있다. 최근에 들어서는 도로 및 철도 분야에서 보강토옹벽 구조물이 좌우에 양립하는 형태, 즉 back-to-back(BTB) 형식의 보강토 옹벽이 도로 및 철도 노반을 지지하는 용도로 많이 적용되고 있으나 그에 대한 연구가 충분하지 않은 실정이다. 본 논문에서는 도로분야에 적용되는 BTB 옹벽의 거동 메카니즘 고찰을 위해 유한요소해석을 통하여 다양한 기하조건 및 보강재 길이로 보강된 BTB옹벽의 거동특성을 분석하고 그 결과를 토대로 폭에 따른 거동 메카니즘과 보강재 길이변화를 통해 옹벽 폭에 대한 최적보강재 길이를 검토하였다.

비특이적 만성 허리통증 환자에 대한 전기자극의 효과 : 국내 데이터베이스의 메타분석 (Effects of Electrical Stimulation on Patients with Non-Specific Low Back Pain : A Meta-Analysis of Domestic Database)

  • 이정우;조성현
    • 대한통합의학회지
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    • 제10권3호
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    • pp.37-52
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    • 2022
  • Purpose : The purpose of this meta-analysis was to evaluate the effects of electrical stimulation on patients with non-specific low back pain. Methods : Domestic databases were gathered from studies that conducted clinical trials associated with electrical stimulation and its impact on pain of non-specific low back patients. A total of 681 studies were identified, with 12 studies satisfying the inclusion data. The studies consisted of patient, intervention, comparison, outcome, and study design (PICO-SD). The search outcomes were items associated with low back pain. Cochrane risk of bias 2 (RoB 2) was used to evaluate the quality of 12 randomized controlled trials. Effect sizes (Hedges's g) in this study were computed as the corrected standard mean difference (SMD). A random-effect model was used to analyze the effect size because of the high heterogeneity among the studies. Egger's regression and 'trim-and-fill' tests were carried out to analyze the publication bias. Cumulative meta-analysis and sensitivity analysis were conducted to analyze the effect according to the sample size and the consistency of the effect size. Results : The following factors had a large overall effect size (Hedges's g=1.28, 95 % CI=.20~2.36) involving electrical stimulation on non-specific low back pain. The subgroup analysis all showed a statistical difference in the types of study design, electrical stimulation, and assessment tool. No statistically significant difference was found in the meta-regression analysis. Publican bias was found in the data. Conclusion : The findings in this study indicate that electrical stimulation interventions have a positive effect on patients with non-specific low back pain. However, due to the low quality of studies and publication bias, the results of our study should be interpreted cautiously.

만성허리통증의 고유수용성신경근촉진법 효과 -국내연구의 메타분석과 체계적 고찰- (Effectiveness of Proprioceptive Neuromuscular Facilitation of Chronic Low Back Pain -A Systematic Review and Meta-analysis of Studies in Korea-)

  • 김범룡;강태우
    • PNF and Movement
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    • 제17권1호
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    • pp.157-166
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    • 2019
  • Purpose: This study compares and examines the effects of proprioceptive neuromuscular facilitation (PNF) on patients with chronic low back pain through systematic literature review and meta-analysis. Methods: Domestic literature was searched with combinations of keywords including "proprioceptive neuromuscular facilitation," "PNF," "back pain," and "low back pain" using the Research Information Sharing Service (RISS), Korean Studies Information Service System (KISS), and Korean Medical Database (KMbase). Six studies (n=148) were finally included in the analysis through a selection and exclusion process. The quality of the studies was evaluated using the PEDro scale. Results: According to the meta-analysis results, the low back pains of the PNF group and the contrast group showed a standardized mean difference (SMD) of 2.21 (95% CI: -3.35, -1.07, p=0.01, $I^2=83%$) after intervention. Thus, the PNF group showed a statistically significant decrease in low back pain compared with the control group. In addition, the SMDs of the Oswestry Disability Index (ODI), lung function, and the Roland and Morris Disability Questionnaire (RMDQ) were -1.34 (95% CI: -1.88, -0.79, p<0.01, $I^2=35%$), 1.14 (95% CI: 0.49, 1.79, p=0.01, $I^2=0%$), and -1.59 (95% CI: -2.56, -0.62, p=0.01, $I^2=46%$), respectively. Thus, the PNF group showed statistically significant differences from the control group. Conclusion: At present, there is some limit to obtaining definite results about effect sizes because there are relatively few randomized controlled experiments that analyze the effects of PNF exercise in patients with chronic low back pain. Therefore, continuous efforts should be made to conduct randomized clinical trials and long-term efficacy studies in the future.

직업성 요통환자에서 재활 프로그램(Back School Program) 도입의 비용-편익분석 (Cost-Benefit Analysis of Back School Program for Occupational Low Back Pain Patients)

  • 주영수;하미나;한상환;권호장;조수헌;김창엽;김선민
    • Journal of Preventive Medicine and Public Health
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    • 제29권2호
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    • pp.347-357
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    • 1996
  • Although occupational low back pain accounts for $20\sim40%$ of all occupational illness and injury, there are limited numbers of studies regarding the effectiveness of back school program. The objective of this study was to evaluate the economic benefit of back school program for early return to work of occupational low back pain patients in the current occupational injury compensation and management system. The cost-benefit analysis in this study was conducted to evaluate the relative magnitude of benefit to cost. The total cost was estimated by calculating the value of components in back school program according to governmental budget protocol. The back school program was consisted of three major approaches, pain center, work-hardening program and funcional restoration program and each of components had various facilities and experts. The total amount of cost was estimated as 250,866,220 won per year. The most promising type of back school program were quite intensive (a 3 to 5-week stay in a specialized center), therefore, if we adopted the 5-week stay course, 10 courses could be held in a year. Following to the medical act, 20 patients per doctor could participate in a each course, ie, total 200 patients in a year. As a result, we could estimate the cost of 1,254,331 won a patient. We estimated the benefit by using data of a few local labor offices about average medical treatment beneficiary and off-duty beneficiary of 46 occupational low back pain patients in 1994. Ullman and Larsson (1977) mentioned that the group of chronic low back pain patients who participated in back school program needed less time to recover by 48.4% of beneficiary duration. And in the trying to estimate the benefit, we asked 10 rehabilitation board certificate doctors about reduction proportion of treatment cost by introducing back school program. The answered reduction proportions were in the range of $30\sim45%$, average 39%. As a final result, we could see that the introduction of back school program in treatment of chronic occupational low back pain patients could produce the benefit to cost ratio as 3.90 and 6.28. And we could conclude that the introduction of back school program was beneficial to current occupational injury compensation and management system.

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점증재하를 고려한 압밀침하 역해석에 의한 강제치환량 추정 (Estimation of replacement depth by consolidation back analysis considering gradual step loading)

  • 전상옥;강병윤;임성훈;정인영
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 2003년도 학술발표논문집
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    • pp.155-158
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    • 2003
  • In this study consolidation back analyses were performed with the data measured in the reservoir construction field. some effects due to gradual step loading were considered carefully in this back analysis. the replacement depth of soft ground was estimated from the difference between the measured and the back analyzed data

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