• 한국안전학회지
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• 제35권5호
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• pp.1-8
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• 2020

Mobile elevating work platforms (MEWPs) consist of a work platform, extending structure, and chassis, and are used to move persons to working positions. MEWPs are useful but are composed of pieces of equipment, and accidents do occur owing to equipment defects. Among these defects, accidents caused by the fracture of bolts fixed to the extension structure and swing system are increasing. This paper presents a failure analysis of the fixing bolts of MEWP. Standard procedure for failure analysis was employed in this investigation. Visual inspection, chemical analysis, tensile strength measurement, microstructural characterization, fractography analysis by Optical Microscope(OM) and Scanning Electron Microscopy(SEM), and finite element analysis (FEA) were used to analyze the failure of the fixing bolts. Using this failure analysis approach, we found the root cause of failure and proposed a means for solving this type of failure in the future. First, the chemical composition of the fixing bolt is obtained by a spectroscopy chemical analysis method, which determined that the chemical composition matched the required standard. The tensile test showed that the tensile and yield strengths were within the required capacity. The stress analysis was carried out at five different boom angles, and it was determined that the fixing bolt of MEWP can withstand the loads at all the boom angles. The outcomes of the fatigue analysis revealed that the fixing bolt fails before reaching the design requirements. The results of the fatigue analysis showed primarily that the failure of the fixing bolt was due to fatigue. A visual inspection of the fractured section of the fixing bolt also confirmed the fatigue failure. We propose a method to prevent failure of the fixing bolt of the MEWP from four different standpoints: the manufacturer, safety certification authority, safety inspection agency, and owner.

• 한국운동역학회지
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• 제26권4호
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• pp.413-420
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• 2016

Objective: The purpose of this study was to analyze and compare different kinds of outdoor walking shoes in terms of muscle fatigue and ground reaction force on walking, and to provide foundational data for developing and choosing outdoor walking shoes that fit the users. Method: The study subjects were 30 healthy men. The experiment was conducted by using outdoor walking shoes with different inner and outer harnesses of the midsole, and shapes of the outsole. For data collection, electromyography was used to measure the muscle fatigue of the anterior tibial muscle and gastrocnemii, which contribute to the dorsiflexion and plantarflexion of the ankle joint, and the biceps muscle of the thigh and lateral great muscles, which contribute to the flexion and extension of the knee joint. A GRF measurement device was used to measure the X, Y, and Z axes. Results: In the type A outdoor walking shoes, regarding the hardness of the midsole, the inner part was soft, while the outer part was hard. The vertical ground reaction force was the lowest, which means least impact while walking and light load to the knees and ankles. The type C outdoor walking shoes were intended to provide a good feel in wearing the shoes. The tibialis anterior, biceps femoris, and gastrocnemii indicate low fatigue, which means that during a long-distance walk, it will minimize the fatigue in the muscles of the lower limbs. Conclusion: To sum up the study results, the different types of outdoor walking shoes indicate their unique characteristics in the biomechanical comparison and analysis. However, the difference was not statistically significant. Thus, a systematic and constant follow-up research should be conducted to cope with expanding market for outdoor walking shoes. Lastly, this study is expected to present foundational data and directions for developing outdoor walking shoes.

• 임상간호연구
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• 제24권2호
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• pp.188-196
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• 2018

Purpose: The purpose of this study was to compare the differences in compassion fatigue, compassion satisfaction and burnout between nurses working at comprehensive nursing care unit and general ward. Methods: The subjects were 35 nurses in general ward and 42 nurses in the Comprehensive Nursing Care unit in one hospital. Measurement instrument included the Stamm's professional quality of life (ProQOL) version 5-Korean. Descriptive statistics, t-test, paired t-test, ANCOVA, and Pearson correlation were used to analyze the data. Results: Nurses working at the Comprehensive nursing care unit demonstrated significantly lower compassion fatigue (F=17.00, p<.001), higher compassion satisfaction (F=14.39, p<.001), and lower levels of burnout (F=40.07, p<.001) than control group. Conclusion: Compassion fatigue and burnout were lower and compassion satisfaction was higher among nurses working at comprehensive nursing unit than general ward. In order to improve quality of the comprehensive nursing care services, there is a need to be concerned with the nurse's compassion fatigue, compassion satisfaction, and burnout.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.241-244
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• 1997

This paper proposes Electronic Speckle Pattern Interferometry(ESPI) for the quantitative buckling analysis of square tube, which is unable to be measured with previous methods. The quantitative buckling analysis in elasticity is important part to study strain-stress analysis of thick-plated tube and fatigue analysis. However, it is unsolved problem with theory and previous experimental method. The merits of ESPI, Whole-filed measurement and high accurate 3D-displacement measurement make it possible to determinate the buckling analysis in elasticity quantitatively.

• 대한조선학회 특별논문집
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• 대한조선학회 2011년도 특별논문집
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• pp.1-4
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• 2011

The full spade rudder for the high speed has advantage to prevent gap cavitation of the rudder. DSME has developed the full spade rudder and GL has carried out CFD analysis and FE analysis to confirm strength and fatigue for DSME and Owner. Necessarily, it needs to compare rudder torque & rudder force between CFD, FE analysis and full scale measurement. This report introduces the measurement method and application of strain gauge for measuring the rudder torque and rudder force for the 8,400 TEU container ship.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.434-439
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• 2021

본 논문은 복강경 자궁근종절제술을 받은 여성에서 정맥 내 아스코르브산 주입이 피로에 미치는 영향 알아보고자 하였다. 우리는 무작위 배정 양측맹검 위약대조 임상시험의 2차 평가변수의 결과를 분석하였다. 복강경 자궁근종절제술을 받은 환자 50명은 수술 중 아스코르브산 (2g)이나 위약을 수술 중 투여받았다. 환자 비율은 임의로 1:1 비로 하였다. 수술 후 2일차에는 간이 피로 평가지 (Brief Fatigue Inventory-Korean version, BFI-K)을 사용하여 피로수준을 평가하였다. 대상자가 동의를 철회하거나 수술을 취소한 경우 또는 평가변수가 측정되지 않은 5명은 제외되어 총 45명(시험군 23명, 대조군 22명)을 대상으로 분석하였다. 분석에 포함된 대상자의 임상적 특성은 실험군과 대조군간의 차이가 없었으며, 전체 피로도 점수도 실험군 (4.56 ± 2.63). 대조군 (5.21 ± 2.02 P = 0.351)으로 두 군간에 차이를 보이지 않았다. 그러나 대조군의 피로도 점수는 대부분의 영역에서 대조군의 피로도 점수보다 낮은 경향을 보였다. 결론적으로 복강경 자궁근종절제술을 시행받은 여성에서 정맥 내 아스코르브산 주입은 피로도를 크게 줄이지 못했으며, 추가적인 연구가 필요하다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1587-1590
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• 2005

A rigid-plastic finite element analysis for the die forging process of a socket ball joint, which is used in the transportation system, was carried out. And also with the results, the elastic stress analysis for the forging die was performed in order to get basic data for the die life prediction. The die fatigue life prediction was simulated using Goodman's and Gerber's equation. The prediction technique for the fatigue life of a forged product, the socket ball joint, using DEFORM-3D is presented and the results are commented upon. Archard's wear model was used for the wear simulation and then the wear simulation and then the wear quantity was quantity was evaluated using volume. In order to prove the wear simulation results to be reliable, wear quantity of the real forging die set in used a forging factory was measured using a 3-dimensional measurement apparatus. The simulation results were relatively in good agreement with the experimental measurements.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.267-268
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• 2006

The cylinder cover stud of low-speed marine diesel engine is more than just a stud. It is a large structural element occasionally weighing over 200 kg used for assembling the combustion chamber components. Therefore, to understand the structural behavior of the stud and design it safely is quite important considering a catastrophic failure which can be arisen from an inadequate use of it. In this paper, the analysis results of the structural behavior of the stud is introduced. Strain measurement results compared with FE analysis results are summarized. The results showed that 1) the stud stress increased with engine operating load, 2) the maximum stress amplitude was about 10 MPa which is far smaller than the stud's fatigue strength of 61 MPa, 3) the stress ratio is higher than 0.9 and the stud's load factor is about 20 %, and 4) about 7 % of initial pressure tightening load was reduced while changing to a nut tightened condition.

• 성인간호학회지
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• 제16권2호
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• pp.211-221
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• 2004

Purpose: The purpose of this study was to describe the pattern of changes on the score of nausea/vomiting and anxiety during one cycle of chemotherapy. Method: A total of 53 subjects who were admitted to C University Hospital for a period of 3 days and 2 nights for chemotherapy were selected from February to April, 2003. Total scores of nausea/vomiting were measured twice a day 3 days for a total of 6 measurements. Anxiety, anorexia, and fatigue were also measured at the first and last measurement points. Data were analyzed by one-way repeated measures, ANOVA, t-test, paired t-test, & Pearson's correlation. Result: The score of nausea/vomiting increased over time except for the 4th measurement point but no changes were significant over time. There were the significant differences between 1st and 2nd, and 2nd and 3rd nausea/vomiting score at p < 0.05. The scores of anxiety, anorexia, and fatigue between the first and 6th points were significantly different(t=-5.69, p=.001; t=6.25, p=.0001; t=3.65, p=.0007). Conclusion: Further studies are needed to identify the relationship between anxiety, and anticipatory and acute nausea/vomiting respectively.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.75-80
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• 2004

Vehicle structures are composed of many substructure connected to one another by various types of mechanical joints. In vehicle engineering it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. It is difficult to obtain the accurate load history of specified positions because of the errors such as modeling, measurement and etc. In the beginning of design exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic force determination is developed by the combination of the principal stresses of F. E. Analysis and experiment. Least square pseudo inverse matrix is adopted to obtain in inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these non. Finally, to verify the proposed procedure, a bus is analyzed. This measurement and prediction technology can be extended to the structural modification of any geometric shape in complex structure.