• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.619-629
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• 2017

This paper focuses on the study of complete dynamic modeling and maximum dynamic load carrying capacity computation of N-flexible links and N-flexible joints mobile manipulator undergoing large deformation. Nonlinear dynamic analysis relies on the Timoshenko theory of beams. In order to model the system completely and precisely, structural and joint flexibility, nonlinear strain-displacement relationship, payload, and non-holonomic constraints will be considered to. A finite element solution method based on mixed method is applied to model the shear deformation. This procedure is considerably more involved than displacement based element and shear deformation can be readily included without inducing the shear locking in the element. Another goal of this paper is to present a computational procedure for determination of the maximum dynamic load of geometrically nonlinear manipulators with structural and joint flexibility. An effective measure named as Moment-Height Stability (MHS) measure is applied to consider the dynamic stability of a wheeled mobile manipulator. Simulations are performed for mobile base manipulator with two flexible links and joints. The results represent that dynamic stability constraint is sensitive when calculating the maximum carrying load. Furthermore, by changing the trajectory of end effector, allowable load also changes. The effect of torsional spring parameter on the joint deformation is investigated in a parametric sensitivity study. The findings show that, by the increase of torsional stiffness, the behavior of system approaches to a system with rigid joints and allowable load of robot is also enhanced. A comparison is also made between the results obtained from small and large deformation models. Fluctuation range in obtained figures for angular displacement of links and end effector path is bigger for large deformation model. Experimental results are also provided to validate the theoretical model and these have good agreement with the simulated results.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.143-151
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• 1997

As the pulse heights from a NaI(Tl) detector vary with the temperature of the measuring environment a significant change in temperature may affect the energy calibration of the spectrometer. The auto-adjustment of the channel corresponding to a pulse heights can be achieved by introducing an external reference source to compensate the temperature dependency of pulse heights, but unfavorable increases of the Compton continuum are caused due to the external source. In this study, the total absorption peaks dominant in the typical environmental gamma spectrum-239 keV from $^{212}Pb$, 351 keV from $^{214}Pb$, 1460 keV from $^{40}K$ and 2614 keV from $^{208}Tl$ for examples - were used as reference in the correction of energy calibration. With these peaks, the program to calibrate the energy of the s spectrum was developed using Microsoft Visual Basic language. The program developed here was applied to the environmental spectra measured at intervals of 30 minutes in the temperature range of from $-20^{\circ}C$ to $10^{\circ}C$ to demonstrate the validity and applicability. As a result of the test, the correction scheme appeared to be effective in the temperature changes encountered in the usual environment.

• Journal of Ocean Engineering and Technology
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• v.27 no.1
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• pp.85-92
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• 2013

This paper deals with the resonant type of a WEC (wave energy converter) and the determination method of its geometric parameters which were obtained to construct the robust and optimal structure, respectively. In detail, the optimization problem is formulated with the constraints composed of the response surfaces which stand for the resonance period(heave, pitch) and the meta center height of the buoy. Use of a signal-to-noise ratio calculated from normalized multi-objective results with the weight factor can help to select the robust design level. In order to get the sample data set, the motion responses of the power buoy were analyzed using the BEM (boundary element method)-based commercial code. Also, the optimization result is compared with a robust design for a feasibility study. Finally, the power efficiency of the WEC with the optimum design variables is estimated as the captured wave ratio resulting from absorbed power which mainly related to PTO (power take off) damping. It could be said that the resultant of the WEC design is the economical optimal design which satisfy the given constraints.

• Steel and Composite Structures
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• v.21 no.3
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• pp.589-604
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• 2016

Kenya has recently experienced worrying collapse of buildings during construction largely attributable to the poor quality of in-situ concrete and poor workmanship. The situation in the country is further compounded by rapid deterioration of infrastructure, hence necessitating the development of alternative structural systems such as concrete filled unplasticized poly vinyl chloride (UPVC) tubes as columns. The work herein adds on to the very limited and scanty work on use of UPVC tubes in construction. This study presents the findings of experimental and analytical work which investigated the structural response of composite concrete filled UPVC tubes under compressive load regime. UPVC pipes are cheaper than steel tubes and can be used as formwork during construction and thereafter as an integral part of column. Key variables in this study included the strength of infill concrete, the length to diameter ratio (L/D) of the plastic tube, as well as the diameter to thickness ratio (D/2t) of the plastic tube. Plastic tubes having varying diameters and heights were used to confine concrete of different strengths. Results obtained in the study clearly demonstrate the effectiveness of UPVC tubes as a confining medium for infill concrete, attributable to enhanced composite interaction between the UPVC tube and infill concrete medium. It was determined that compressive strength of the composite column specimens increased with increased concrete strength while the same decreased with increased column height, albeit by a small margin since all the columns considered were short columns. Most importantly, the experimental confined concrete strength increased significantly when compared to unconfined concrete strength; the strength increased between 1.18 to 3.65 times the unconfined strength. It was noted that lower strength infill concrete had the highest confined strength possibly due to enhanced composite interaction with the confining UPVC tube. The study further proposes an analytical model for the determination of confined strength of concrete.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.3
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• pp.90-96
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• 2004

The objective of this study was to develop a model for safe work load based on a physiological model of metabolic energy of manual material handling tasks. Fifteen male subjects voluntarily participated in this study. Lifting activities with four different weights, 0, 8, 16, 24kg, and four different working frequencies (2, 5, 8, 11 lifts/min) for a lifting range from floor to the knuckle height of 76cm were considered. Oxygen consumption rates and heart rates were measured during the performance of sixteen different lifting activities. Simplified predictive equations for estimating the oxygen consumption rate and the heart rate were developed. The oxygen consumption rate and the heart rate could be expressed as a function of task variables; frequency and the weight of the load, and a personal variable, body weight, and their interactions. The coefficients of determination ($r^2$) of the model were 0.9777 and 0.9784, respectively, for the oxygen consumption rate and the heart rate. The model of oxygen consumption rate was modified to estimate the work load for the given oxygen consumption rate. The overall absolute percent errors of the validation of this equation for work load with the original data set was 39.03%. The overall absolute percent errors were much larger than this for the two models based on the US population. The models for the oxygen consumption rate and for the work load developed in this study work better than the two models based on the US population. However, without considering the biomechanical approach, the developed model for the work load and the two US models are not recommended to estimate the work loads for low frequent lifting activities.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.55-60
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• 2006

Draw-bead is applied to control the material flow in a stamping process and improve the product quality by controlling the draw-bead restraining force (DBRF). Actual die design depends mostly on the trial-and-error method without calculating the optimum DBRF. Die design with the predicted value of DBRF can be utilized at the tryout stage effectively reducing the cost of the product development. For the prediction of DBRF, a simulation-based prediction model of the circular draw-bead is developed using the Box-Behnken design with selected shape parameters such as the bead height, the shoulder radius and the sheet thickness. The value of DBRF obtained from each design case by analysis is approximated by a second order regression equation. This equation can be utilized to the calculation of the restraining force and the determination of the draw-bead shape as a prediction model. For the evaluation of the prediction model, the optimum design of DBRF in sheet metal forming is carried out using response surface methodology. The suitable type of the draw-bead is suggested based on the optimum values of DBRF. The prediction model of the circular draw-bead proposes the design method of the draw-bead shape. The present procedure provides a guideline in the tool design stage for sheet metal forming to reduce the cost of the product development.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.5
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• pp.693-699
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• 2004

Live animal selection programs that favor animals with a minimum amount of carcass fat are used for improving breeding flocks of sheep. To predict carcass characteristics of live sheep using body measurements in breeding flocks, 200 male and female lambs of two fat-tailed Iranian sheep breeds (Moghani and Makui) were used. Depth of soft tissue over the 12th rib of the live animals was measured with ultrasound (ULGR) and with hypodermic needle (NGR). The height at withers (HW), body length (BL), circumference of heart girth (CH) and width of hooks (WH), were measured. All animals were slaughtered; carcasses were cut into joints and dissected. Breed had a significant effect on all of the live easurements. The Moghani breed showed a higher value for HW, CH, ULGR and NGR, compared to that of Makui. Except for soft tissue depths; ULGR, NGR and GR, the male lambs showed higher values in live and carcass measurements than females. Percentages of carcass, total fat and intermuscular fat in females were higher than that of male lambs. In spite of the higher amount of subcutaneous and intermuscular fat in female (which is usually used for their physiological need, such as pregnancy and lactation), the male lambs had a heavier fat-tail than females. There was a wide range of variation of percentage of total carcass fat and total chemical fat content of carcass in the two breeds. Eventually this wide variation could be use by animal breeders for selection of animals with a lesser amount of carcass fat. Live weight of lambs showed a relatively low correlation with percentage of carcass lean, total fat and subcutaneous and intermuscular fat. Total lean meat was predicted with relatively high coefficients of determination in the two breeds ($R^2$=0.61 and 0.89, respectively). Live weight and carcass traits were predicted using simple measurements, but with $R^2$ ranging from 0.53 to 0.93.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1659-1664
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• 2008

To study the working mechanisms for non-starch polysaccharidases to improve the growth performance of broiler chickens, a 21-day feeding trial was conducted. Two dietary treatments were included: 1) wheat diet (the control); 2) wheat+xylanase diet (xylanase, Allzyme PT, Alltech, Kentucky, USA). There were 8 replicates with 8 birds each for each treatment and the experimental diets were given to birds from hatch. Feed intake and body weight were measured on days 7 and 21. At the same ages, samples were taken for the determination of selected groups of luminal and mucosa-associated bacteria, mucosal morphology, brush-border membrane (BBM) bound enzyme activity and ileal nutrient digestibility. The xylanase supplement increased (p<0.05) body weight gain (BWG) and improved feed conversion ratio (FCR) at the end of the experiment but protein and starch digestibilities were not affected (p>0.05) by xylanase. Up to day 7, xylanase increased the counts of C. perfringens in the ileum and total anaerobic bacteria (TAB) in the caeca (p<0.05, p=0.07, respectively). By day 21, the counts of ileal lactobacilli (p<0.05) and TAB (p=0.07) were lower in birds given the xylanase-supplemented diet than in those on the control diet. No significant differences were observed in the counts of mucosa-associated lactobacilli and coliforms between xylanase treatment and the control at both ages. Villus height at the jejunum was not affected (p>0.05) by the supplement but crypt depth at the same site was reduced at day 7. Also, xylanase tended to increase the concentration of BBM protein (p = 0.09) and the specific activity of sucrase (p = 0.07) at day 21.

• Journal of Nutrition and Health
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• v.30 no.8
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• pp.960-975
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• 1997

This study was carried out to evaluate the iron nutrition status of 212 middle school students(106 males and 106 females) residing in Seoul(13-14 years old ) using eating patterns and a measurement of anthropometrical determination and hematological indices. Fasting blood samples were taken from all subjects, serum iron (SI) and total iron binding capacity(TIBC) concentrations were measured, and transferrin saturation(TS) levels were calculated. Iron and other nutrient intakes were estimated by a semi-quantitative frequency questionnaire. The level of TS(%) which was calculated with TIBC and SI in females(20.4$\mu\textrm{g}$/dl) was significantly lower(p<0.050 than that of males (27.4$\mu\textrm{g}$/㎗). The prevalence of iron deficiency was found to be 36.7% when defined by TS(%) (<05%). Mean daily intake of total iron in the study subjects was 14mg and heme iron intake was 5.4mg(38.1%) . There was a significant negative correlation between the level of SI and the income level and a positive correlation with the level of TIBC and the income level. TIBC had a positive correlation with the anthropometric variables(Ht, Wt, BMI, RI and PIBW). SI and TS had a negative correlation with body fat percentage. There was a positive correlation between energy intake and TIBC only among females. The logistic regression analysis revealed that income level, body fat percentage , weight and energy intake were major determinants of low SI levels. Among the determinants of abnormal TIBC levels were weight , height, income level and energy intake. Finally , among those of low TS% were iron and energy intake and income level. These observations suggest that physical status, body fat percentage energy and iron intakes and income level are risk factors for iron-deficiency anemia among the middle school students in Seoul.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.4
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• pp.295-300
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• 2015

The precise determination of the activity for each radionuclide in environmental samples requires the self-absorption correction factor. In this research, we derived the self-absorption correction factor for three p-type high purity germanium detectors using the Monte Carlo code MCNPX. These detectors have different characteristics such as crystal diameter, height and size of the core. We compared the calculated full-energy peak efficiency with the experimental value using a standard sample with $1g/m^3$ density and verified the modeling. We simulated the dependency of the full-energy peak efficiency on the 0.3, 0.6, 0.9, 1.0, 1.2 and $1.5g/m^3$ samples and obtained the corresponding self-absorption correction factor. The self-absorption correction factors calculated for the three detectors differ by less than 1% over most of the energy range and sample densities considered. This indicates that the self-absorption correction factors are independent of the crystal characteristics of HPGe detector.