• Transactions of Materials Processing
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• v.31 no.5
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• pp.296-301
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• 2022

In this study, influence of the process parameters of the roller leveling process on the straightness of the steel wire was analyzed using numerical analysis. To construct the numerical analysis model, cross-sectional and longitudinal element sizes, which affect the prediction accuracy of longitudinal stress caused by bending deformation of the steel wire, were optimized, and mass scaling that satisfies prediction accuracy while reducing computational time was confirmed. By using the constructed numerical analysis model, the influence of various process parameters such as input direction of the steel wire, initial diameter of the steel wire, back tension and intermesh on the straightness was confirmed. The simulation result shows that the 3^rd and 4^th roller of vertical straightener had a significant influence on vertical shape of the steel wire.

• Fashion & Textile Research Journal
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• v.23 no.2
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• pp.237-246
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• 2021

This study aims to analyze short sleeve cycling tops from three brands for a change in garment fit and pressure depending on the static and cycling postures. To this end, it used a 3D virtual garment system to virtualize the garments. Further, a cross-section of the 3D virtual garment data was obtained, and the space length was measured in the design-X program to prove the objectivity of the 3D virtual garment. The results indicated that three brands had a large space length at the front than the back because of the bent posture in cycling. Therefore, appropriate ease was required for the waist and abdomen. Although there were various cutting lines of the bodice panel by brand, the design of the cutting lines should consider the changes in the surface to reflect the bent posture in cycling. The results of this experiment confirmed that the wrinkles present in the 3D virtual garment were reflected in the cross-section and that the space length was small in the high-stress area, as shown in red. Therefore, it was proven the stress of the 3D virtual garment could be used for 3D virtual garment evaluation.

• Computers and Concrete
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• v.29 no.4
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• pp.209-217
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• 2022

In order to analyze the static and dynamic structural characteristics of the Obermeyer gate under overflow conditions, the force characteristics and vibration characteristics of the shield plate structure are studied based on the fluid-solid coupling theory. In this paper, the effects of the flow rate, airbag pressure and overflow water level on the structural performance of shield plate of air shield dam are explored through the method of controlling variables. The results show that the maximum equivalent stress and total deformation of the shield plate decrease first and then increase with the flow velocity. In addition, they are positively correlated with the airbag pressure. What's more, we find that the maximum equivalent stress of the shield plate decreases first and then increases with the overflow water level, and the total deformation of the shield plate decreases with the overflow water level. What's more importantly, the natural frequency of the shield structure of the Obermeyer gate is concentrated at 50 Hz and 100 Hz, so there is still the possibility of resonance. Once the resonance occurs, the free edge of the shield vibrates back and forth. This work may provide a theoretical reference for the safe and stable operation of the shield of the Obermeyer gate.

• Physical Therapy Korea
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• v.31 no.2
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• pp.159-166
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• 2024

Background: For instance, forward head posture (FHP), characterized by the forward movement of the head relative to the spine, places significant stress on the neck and upper back muscles, disrupting the biomechanical balance of the body. Objects: The objective of this study was to probe the biomechanical effects of FHP on musculoskeletal health through a relative analysis of 26 adults diagnosed with FHP and 26 healthy controls. Methods: In this study, we evaluated the biomechanical impacts of FHP. Participants adjusted their head positions and underwent muscle strength tests, including electromyography assessments and the Biering-Sørensen test for trunk muscle endurance. Data analysis was conducted using Kinovea (Kinovea) and IBM SPSS software ver. 26.0 (IBM Co.) to compare muscle activities between groups with normal and FHPs. Results: The study shows that individuals with FHP have significantly lower muscle activity, endurance, and spinal extension in the erector spinae compared to those without, highlighting the detrimental effects of FHP on these muscles. Conclusion: This study underscores the impact of FHP on erector spinae function and emphasizes the need for posture correction to enhance musculoskeletal health and guide future research on intervention strategies.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.643-659
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• 2022

Geologic sequestration technologies such as CCS (carbon capture and storage), EGS (enhanced geothermal systems), and EOR (enhanced oil recovery) have been widely implemented in recent years, prompting evaluation of the mechanical stability of storage sites. As fluid injection can stimulate mechanical instability in storage layers by perturbing the stress state and pore pressure, poroelastic models considering various injection scenarios are required. In this study, we calculate the pore pressure, stress distribution, and vertical displacement along a surface using commercial finite element software (COMSOL); fault slips are subsequently simulated using PyLith, an open-source finite element software. The displacement fields, are obtained from PyLith is transferred back to COMSOL to determine changes in coseismic stresses and surface displacements. Our sequential use of COMSOL-PyLith-COMSOL for poroelastic modeling of fluid-injection and induced-earthquakes reveals large variations of pore pressure, vertical displacement, and Coulomb failure stress change during injection periods. On the other hand, the residual stress diffuses into the remote field after injection stops. This flow pattern suggests the necessity of numerical modeling and long-term monitoring, even after injection has stopped. We found that the time at which the Coulomb failure stress reaches the critical point greatly varies with the hydraulic and poroelastic properties (e.g., permeability and Biot-Willis coefficient) of the fault and injection layer. We suggest that an understanding of the detailed physical properties of the surrounding layer is important in selecting the injection site. Our numerical results showing the surface displacement and deviatoric stress distribution with different amounts of fault slip highlight the need to test more variable fault slip scenarios.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3644-3649
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• 2013

Automotive seat recliner has the function to control the angle at the back of chair and has the relation close to the safety of seat. Therefore each of parts constituting the recliner is important and the recliner housing to protect these parts from various dynamic loads is also important. In this study, the recliner housing with t=3mm which is made of high tension steel plate(SPFC 980) is applied to actual automotive seat. The deformation is investigated through the durability tester. Deformation and equivalent stress are also analyzed by simulation analysis under the same condition with experiment. After recliners with thicknesses of 1mm and 2mm are modeled by bases of experimental and analysis values, deformation and equivalent stress are investigated through structural analysis.

• Journal of Aquaculture
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• v.12 no.3
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• pp.221-228
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• 1999

The effects of sparp changes of water temperature (WT) on the stree response and physiological change of the cultured olive flounder (Paralichthys olivaceus) were examined by manipulating WT (3 patterns) in a running seawater culture system. In the first group (Exp. I), the WT was decreased from 18$^{\circ}C$ to 11$^{\circ}C$ within 6 hours and increased back to the original WT quickly. WT was decreased from 2$0^{\circ}C$ to 11$^{\circ}C$ within 5 hours and main-tained at 11$^{\circ}C$ for 10 hours. and then increased to 2$0^{\circ}C$ in the second group (Exp. II). In the third group(Exp. III) WT was decreased to 11$^{\circ}C$ within 5 hours (type A) or 10 hrs. (type B). In Exp. I and III, the level of serum cortisol was increased from 2.5$\pm$0.3 ng/ml and 2.6$\pm$0.9 ng/ml to 13.6$\pm$3.0 ng/ml and 12.4$\pm$3.2ng/ml, respectively, with WT decrease. However, no consistent tendency in the change of serum glucose level was shown according to WT decrease. In Exp. III, the glucose level of fish in type A was decreased until 5 hours and increased at 7 hours, then decreased until 12 hours where as the glucose level in type B was decreased until 5 hours and stayed at the level of 15.7 mg/dl. The serum osmolality was reduced with WT decrease and the response of serum electrolytes in this experiment conflicted, and a tendency in total protein, AST and ALT was not found following WT decrease. In conclusion, olive flounder responded to the stress caused by WT decrease and acclimated to this condition when the lower temperature was maintained. But there was no stress response in the blood of olive flounder when WT was increased. On the other hand, the degree of stress response in olive flounder was various according to the range and gradient of WT change.

• Fashion & Textile Research Journal
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• v.2 no.3
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• pp.265-271
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• 2000

Heat stress results in fatigue, a decline in strength, alertness., and mental capacity. The problem is compounded when high humidity exists. To help relieve worker heat stress, many types of cooling units are marketed. While workers may experience some cooling, critical body core temperatures often continue to elevate. This study was designed to find the effects of three kinds of cooling vest with portable frozen gel strips on thermophysiological parameters and on temperature and humidity within clothing. The heart rate, rectal, and skin temperature as well as sweat rate and clothing microclimate were measured during 80 min in 5 healthy males. Inquiries were also made into the subjective rating thermal, humidity comfort, and fatigue sensations. The main findings in our experiments are as follows: (a) Physiological parameters such as rectal temperature was the lowest in garb A1, intermediate in garb A, and the highest in garb A2 throughout the experiment. And mean skin temperature was the lowest in garb A, intermediate in garb A1, and the highest in garb A2; (b) Temperature and humidity within clothing (back) were garb in Al, intermediate in garb A, and the highest in garb A2. But the temperature and humidity within clothing (chest) were garb in A, intermediate in garb A1, and the highest in garb A2; (c) Most participants (4 out of 5 persons) answered that they felt more comfortable and fatigueless in garb A1 than in garb A and A2. It is concluded that local cooling in garb A1 of the upper torso could physiological reduce the thermal strain in participants wearing cooling vest.

• Journal of Korean Society of Steel Construction
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• v.18 no.2
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• pp.203-211
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• 2006

This paper presents a new, effective torsional constant for thin-waled open beams under concentrated and uniformly distributed torques. The proposed constant can be used directly, instead of the St. Venant torsional constant, for any generic comemrcial finite-element program, without modifying the algorithm. The derived torsional constant accounts for both the pure torsion and the warping torsion, and is equal to the St. Venant torsion constant times a correction factor. It is also shown, in the case of the St. Venant torsion, that the derived constant is identical to the torsional constant. The derived effective torsional constant is different from the one given by Elhelbawey et al. The pure torsional shear stress, the warping shear stress, and the warping normal stress were also determine d, using the maximum twisting angle. The accuracy of the proposed torsional constant was validated by comparing the numerical results with the closed-form solutions or other numerical results available in the literature.

• Korean Journal of Materials Research
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• v.32 no.11
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• pp.508-514
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• 2022

Piezoelectric composite films which are enabled by inorganic piezoelectric nanomaterials-embedded polymer, have attracted enormous attention as a sustainable power source for low powered electronics, because of their ease of fabrication and flexible nature. However, the absorption of applied stress by the soft polymeric matrices is a major issue that must be solved to expand the fields of piezoelectric composite applications. Herein, a flexible and porous piezoelectric composite (piezoelectric sponge) comprised of BaTiO₃ nanoparticles and polydimethylsiloxane was developed using template method to enhance the energy conversion efficiency by minimizing the stress that vanishes into the polymer matrix. In the porous structure, effective stress transfer can occur between the piezoelectric active materials in compression mode due to direct contact between the ceramic particles embedded in the pore-polymer interface. The piezoelectric sponge with 30 wt% of BaTiO₃ particles generated an open-circuit voltage of ~12 V and a short-circuit current of ~150 nA. A finite element method-based simulation was conducted to theoretically back up that the piezoelectric output performance was effectively improved by introducing the sponge structure. Furthermore, to demonstrate the feasibility of pressure detecting applications using the BaTiO₃ particles-embedded piezoelectric sponge, the composite was arranged in a 3 × 3 array and integrated into a single pressure sensor. The fabricated sensor array successfully detected the shape of the applied pressure. This work can provide a cost-effective, biocompatible, and structural strategy for realizing piezoelectric composite-based energy harvesters and self-powered sensors with improved energy conversion efficiency.