• Safety and Health at Work
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• 제6권2호
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• pp.120-127
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• 2015

Background: Musculoskeletal pain (MSP) is a common and disabling problem among carpet weavers and is linked to physical and psychosocial factors of work. This study aimed to determine the prevalence of MSP, its psychosocial risk factors, and association of pain in each pair of anatomical sites among carpet weavers. Methods: A cross-sectional study was performed among 546 hand-woven carpet weavers in rural small-scale workshops of Iran. Data were collected by using parts of a standardized CUPID (Cultural and Psychosocial Influences on Disability) questionnaire focused on MSP in 10 body sites, including the low-back, neck, both right and left shoulders, elbows, wrists/hands, individual, physical and psychosocial risk factors. Statistical analysis was performed applying logistic regression models. Results: Prevalence of MSP in at least one body sitewas 51.7% over the past month. The most common sites were low back and right shoulder pain 27.4% and 20.1%, respectively. A significant difference was found between the mean number of painful anatomical sites and the level of education, age, physical loading at work, time pressure, lack of support, and job dissatisfaction. In pairwise comparisons, strongest association was found between pain in each bilateral anatomical site (odds ratio = 11.6-35.3; p < 0.001). Conclusion: In home-based workshops of carpet weaving, psychosocial factors and physical loading were associated with MSP. This finding is consistent with studies conducted among other jobs. Considering the preventive programs, the same amount of attention should be paid to psychosocial risk factors and physical loading. Also, further longitudinal studies are needed to investigate the relationship of psychological factors.

• Journal of Nutrition and Health
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• 제2권4호
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• pp.135-142
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• 1969

To investigate the influences of physical exercises on lipid metabolism in human, serum lipids were determined in swimming, weight lifting and wrestling athletes after loading their proper exercises for certain periods of time. Atherolipid numbers were also determined in these hardly exercising athletes. Besides same time, experimental studies were carried out in rats to see the effects of high-carbohydrate, high-lipid and high-protein diets of 1, 2, 4 and 8 weeks duration upon serum total cholesterol level after the physical exercises. The results obtained were as follows: 1. In studies with athletes, the serum concentration of various forms lipids and atherolipid number were increased for some periods of time by imposing physical exercises. 2. In experimental studies with rats, various dietary effect upon the serum total cholosterol level after loading physical exercises were as follow; on high-lipid diets, the serum level increased upto the 4th week and thereafter kept the same increased level until the 8th week; on high-carbohydrate diet, the level increased upto the 2nd week and extended to the 4th week with the same increased level, but somewhat decreased at the 8th week; and on the high-protein diet, the level increased upto the 2nd week, and decreased progressively from the 4th week.

• Structural Engineering and Mechanics
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• 제60권6호
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• pp.939-952
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• 2016

A compression to tensile load transforming (CTT) device was developed to determine indirect tensile strength of concrete material. Before CTT test, Particle flow code was used for the determination of the standard dimension of physical samples. Four numerical models with different dimensions were made and were subjected to tensile loading. The geometry of the model with ideal failure pattern was selected for physical sample preparation. A concrete slab with dimensions of $15{\times}19{\times}6cm$ and a hole at its center was prepared and subjected to tensile loading using this special loading device. The ratio of hole diameter to sample width was 0.5. The samples were made from a mixture of water, fine sand and cement with a ratio of 1-0.5-1, respectively. A 30-ton hydraulic jack with a load cell applied compressive loading to CTT with the compressive pressure rate of 0.02 MPa per second. The compressive loading was converted to tensile stress on the sample because of the overall test design. A numerical modeling was also done to analyze the effect of the hole diameter on stress concentrations of the hole side along its horizontal axis to provide a suitable criterion for determining the real tensile strength of concrete. Concurrent with indirect tensile test, the Brazilian test was performed to compare the results from two methods and also to perform numerical calibration. The numerical modeling shows that the models have tensile failure in the sides of the hole along the horizontal axis before any failure under shear loading. Also the stress concentration at the edge of the hole was 1.4 times more than the applied stress registered by the machine. Experimental Results showed that, the indirect tensile strength was clearly lower than the Brazilian test strength.

• 펄프종이기술
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• 제44권4호
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• pp.62-68
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• 2012

This study was carried out to evaluate the effect of PCC loading at thick stock on the physical properties of paper. The effect of starch addition(2, 4 and 6%) and mixing time(5, 10 and 20 min.) on the filler retention and paper properties were investigated. Optimum dosage of cationic starch as a fixing agent was 4%, and mixing time did not showed any significant effect on the filler retention. PCC loading at thick stock was more effective to improve bulk and opacity than PCC loading at thin stock, although their improvement was not so significant. It was also found that the strength properties could be improved by the loading at thick stock. PCC loading method at thick stock could be considered as one of potential approaches for further improving of paper properties, although further research works are required in order to apply the PCC loading at thick stock in the paper mill.

• The Journal of Advanced Prosthodontics
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• 제15권1호
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• pp.33-43
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• 2023

PURPOSE. This study investigated the physical and mechanical changes in the titanium base of three different hybrid abutment materials after cyclic loading by estimating the post-load reverse torque value (RTV), compressive side fulcrum wear pattern of titanium base, and surface roughness. MATERIALS AND METHODS. A total of 24 dental implants were divided into three groups (n = 8 each): Group Z, LD, and P used zirconia, lithium disilicate, and polyetheretherketone, respectively, for hybrid abutment fabrication. RTV was evaluated after cyclic loading with 50 N for 1.2 × 10⁶ chewing cycles. The compressive sides of the titanium bases were analyzed using a scanning electron microscope, and the roughness of the affected areas was measured using an optical profilometer after loading. Datasets were analyzed using Kruskal-Wallis test followed by Mann-Whitney tests with the Bonferroni correction (α = .05). RESULTS. Twenty-three samples passed the test; one LD sample fractured after 770,474 cycles. Post-load RTV varied significantly depending on the hybridabutment material (P = .020). Group P had a significantly higher median of post-load RTVs than group Z (16.5 and 14.3 Ncm, respectively). Groups LD and P showed minor signs of wear, and group Z showed a more pronounced wear pattern. While evaluating compressive side affected area roughness of titanium bases, lower medians were shown in group LD (Ra 0.16 and Rq 0.22 ㎛) and group P (Ra 0.16 and Rq 0.23 ㎛) than in group Z (Ra 0.26 and Rq 0.34 ㎛); significant differences were found only among the unaffected surface and group Z. CONCLUSION. The hybrid abutment material influences the post-load RTV. Group Z had a more pronounced wear pattern on the compressive side of titanium base; however, the surface roughness was not statistically different among the hybridabutment groups.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.177-190
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• 2008

Material failure behavior is generally dependent on loading rate. Especially in brittle and quasi-brittle materials, rate dependent material behavior can be significant. Empirical formulations are often used to predict the rate dependency, but such methods depend on extensive experimental works and are limited by practical constraints of physical testing. Numerical simulation can be an effective means for extracting knowledge about rate dependent behavior and for complementing the results obtained by testing. In this paper, the failure behavior of a brittle material under different loading rates is simulated by molecular dynamics analysis. A notched specimen is modeled by sub-million particles with a normalization scheme. Lennard-Jones potential is used to describe the interparticle force. Numerical simulations are performed with six different loading rates in a direct tensile test, where the loading velocity is normalized to the ratio of the pseudo-sonic speed. As a consequence, dynamic features are achieved from the numerical experiments. Remarkable failure characteristics, such as crack surface interaction/crack arrest, branching, and void nucleation, vary in case of the six loading cases. These characteristics are interpreted by the energy concept approach. This study provides insight into the change in dynamic failure mechanism under different loading rates.

• Ocean Systems Engineering
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• 제12권1호
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• pp.23-38
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• 2022

In this paper, a pitch-type wave energy converter (WEC-rotor) is investigated in irregular wave conditions for the real sea testing at the west coast of Jeju Island, South Korea. The present research builds on and extends our previous work on regular waves to irregular waves. The hydrodynamic characteristics of the WEC-rotor are assessed by establishing a quasi-two-dimensional numerical wave tank using computational fluid dynamics by solving the Reynolds-averaged Navier-Stokes equation. The numerical solution is validated with physical experiments, and the comparison shows good agreement. Furthermore, the hydrodynamic performance of the WEC-rotor is explored by investigating the effect of the power take-off (PTO) loading torque by one-way and two-way systems, the wave height, the wave period, operational and high sea wave conditions. Irrespective of the sea wave conditions, the absorbed power is quadratic in nature with the one-way and two-way PTO loading systems. The power absorption increases with the wave height, and the increment is rapid and mild in the two-way and one-way PTO loading torques, respectively. The pitch response amplitude operator increases as the wave period increases until the maximum value and then decreases. For a fixed PTO loading, the power and efficiency are higher in the two-way PTO loading system than in the one-way PTO loading system at different wave periods.

• 대한물리의학회지
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• 제8권4호
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• pp.525-532
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• 2013

PURPOSE: The aim of this study was to compare the effects of different loading swimming exercises on muscle recovery after sciatic nerve crush injury in rats. METHODS: For this study, thirty-one Sprague-Dawley male rats were randomly divided into five groups. There were the negative control group (NCG, n=5), the positive control group (PCG, n=7), the low intensity swimming exercise group (LISEG, n=7), the moderate intensity swimming exercise group (MISEG, n=7) and the high intensity swimming exercise group (HISEG, n=5). Each rat was weighed to determine the lead weight to be attached to the base of its tail. Subsequently, the PCG, the LISEG, the MISEG and the HISEG were underwent standard unilateral sciatic nerve crush. The LISEG (no load), the MISEG (lead weight equivalent to 2% average body mass) and the HISEG (lead weight equivalent to 4% average body mass) were received the 10 minute swimming exercise in a day for 10 days. The NCG and PCG were not received with any therapeutic intervention. The diameter of the calf muscle and the level of serum lactate dehydrogenase (LDH) were measured to detect the effects of the swimming exercise. RESULT: The maximum diameter of the calf muscles was significantly increased after seventh swimming exercise in the LISEG, the MISEG and the HISEG compared with the PCG (p<0.05). However, there was no statistically significant difference between the LISEG, the MISEG and the HISEG. Also, the level of the serum LDH was significantly decreased in the LISEG, the MISEG and the HISEG compared with the PCG (p<0.05). CONCLUSION: Taken together, these results suggest that swimming exercise could accelerate muscle recovery processes after crush injury, but the different intensity of the swimming exercise does not affect healing processes.

• The Journal of Korean Physical Therapy
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• 제22권5호
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• pp.71-76
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• 2010

Purpose: The present study was designed to investigate the effect of a Rollator on plantar pressure and foot balance during gait in older adults. Methods: Twenty consecutive subjects (8 men, 12 women; age: $69.9{\pm}8.9$) had the following measurements done: plantar pressure in 10 areas of the foot, foot balance including heel rotation, foot balance, forefoot balance, medial forefoot balance, and meta loading during gait with or without a Rollator. Results: Significant differences in plantar pressure were observed in the areas of toes 2-5 or etatarsal areas 1, 4, 5 during gait with and without a Rollator. There were no significant differences in other areas of the foot. Regarding foot balance during gait with or without a Rollator, there were statistically significant differences in heel rotation, forefoot balance, medial forefoot balance, and meta loading. Conclusion: For older adults, the use of a Rollator can decrease plantar pressure and increase foot balance in various foot areas.

• 대한물리치료과학회지
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• 제27권1호
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• pp.34-42
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• 2020

Background: The purpose of this study was to investigate the effects of ipsilateral and contralateral load changes during single-leg standing on the leg muscle activities of healthy people. Design: Randomized controlled trial. Methods: For all the subjects, a load was randomly applied to the ipsilateral or the contralateral side. While the load was applied, the subject raised a hand and then performed single-leg standing for 10 seconds using the dominant side. Results: During single-leg standing, the muscle activity of the gluteus medius, peroneus longus on the supporting side increased statistically significantly when an upper limb load was applied contralaterally, but no statistically significant differences were detected in the muscle activities of the tibialis anterior and the gastrocnemius using a test of within-subjects effects. Conclusion: It can be seen that muscle activities increase during exercise when the amount and frequency of a load are increased and when the same load is applied to different sides of the body. Such muscle activity increases may be applied to change the intensity of exercise when one is in a static posture, such as during single-leg standing.