• Steel and Composite Structures
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• v.51 no.4
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• pp.363-375
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• 2024

Within the optimization field, addressing the intricate posed by fluidic pressure loads on functionally graded structures with frequency-related designs is a kind of complex design challenges. This paper thus introduces an innovative density-based topology optimization strategy for frequency-constraint functionally graded structures incorporating Darcy's law and a drainage term. It ensures consistent treatment of design-dependent fluidic pressure loads to frequency-related structures that dynamically adjust their direction and location throughout the design evolution. The porosity of each finite element, coupled with its drainage term, is intricately linked to its density variable through a Heaviside function, ensuring a seamless transition between solid and void phases. A design-specific pressure field is established by employing Darcy's law, and the associated partial differential equation is solved using finite element analysis. Subsequently, this pressure field is utilized to ascertain consistent nodal loads, enabling an efficient evaluation of load sensitivities through the adjoint-variable method. Moreover, this novel approach incorporates load-dependent structures, frequency constraints, functionally graded material models, and polygonal meshes, expanding its applicability and flexibility to a broader range of engineering scenarios. The proposed methodology's effectiveness and robustness are demonstrated through numerical examples, including fluidic pressure-loaded frequency-constraint structures undergoing small deformations, where compliance is minimized for structures optimized within specified resource constraints.

• Journal of computational fluids engineering
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• v.1 no.1
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• pp.112-122
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• 1996

A finite element scheme using the concept of PISO method has been developed to solve the Navier-Stokes viscous flows in all speed range. This scheme includes development of new pressure equation that retains both the hyperbolic term related with the density variation and the elliptic term reflecting the incompressibility constraint. The present method is applied to the incompressible two-dimensional driven cavity flow problems(Re=100, 400 and 1,000). For compressible flows, the Carter plate problem(M=3 and Re=1,000) is computed. Finally, we have simulated the shock-boundary layer interaction(M=2 and Re=2.96×10/sup 5/), a more difficult problem, and compared its results with the experiment to demonstrate the shock capturing capability of the present solution algorithm.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.4
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• pp.324-333
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• 2005

The kinetics of external hydrogen embrittlememt is considered. The equation of the crack growth rate (CGR) is derived from modification of the model developed by Wilkinson and Vitek. After calculation of hydrogen pressure build-up in the void, the effect of the internal hydrogen pressure on the void growth is added. The CGR is expressed by two terms. One is the term dependent on the critical stress, which is exactly same as Wilkinson and Vitek. The other is term dependent on the pressure of the hydrogen in void.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.4
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• pp.1676-1682
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• 2018

The purpose of this study was to investigate the short-term effects of lumbar rotational mobilization under the single-leg standing (SLS) position. Fifteen healthy individuals were recruited, and randomized to agroup of trunk rotational exercise (TRE) and lumbar rotational mobilization (LRM). Trunk twist rotational exercise was performed to the TRE group, and mobilization was applied to the LRM group on the lumbar spine. Velocity of the center of pressure (VCOP) and center of pressure (COP) for each participant were measured through SLS. COPs were not significantly increased or decreased after treatment in both groups. VCOPs also did not change considerably except on the right side when the eye was closed. There was no significant difference between COPs and VCOPs in two groups. This study suggests that trunk rotation exercise and lumbar rotation mobilization would have similar effects on balance ability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3390-3399
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• 2013

The purpose of this study was to examine the incidence rates of pressure ulcers depending on the types of healthcare organizations and to determine whether the characteristics of patients and facilities influence on the incidence of pressure ulcers in long term facilities. We analyzed data on 796,857 patients of the 2009 National Patient Sample which was extracted from to claims for medical fees to Health Insurance Review & Assesment Service(HIRA). A total of 3.2% of patients(n=25,339) had at least 1 pressure ulcer during their hospitalization. The pressure ulcer rates were highest in long term care facilities(8.2%, n=11,895) following general hospital(2.7%, n=8,052), hospital(1.7%, n= 5,059). According to logistic regression analysis, urinary incontinence (Odds ratio(OR)=2.462, 95% confidence interval(CI)=2.038-2.974), hypertension(OR=1.456, CI=1.400-1.515), peripheral vessel diseases (OR=1.357, CI=1.200-1.534) were significant predictors of pressure ulcers. As the number of diagnoses, age, and the number of doctors per 100 beds increased, the incidence of pressure ulcers increased. In addition, more number of beds was associated with fewer pressure ulcers.

• The KSFM Journal of Fluid Machinery
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• v.17 no.3
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• pp.46-51
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• 2014

In this study, a numerical analysis methodology is studied to predict thermal and flow characteristics of C3X vane with internal cooling. Effects of turbulence models, transition models and viscous work term on temperature and pressure distributions on the vane surface are investigated. These optional terms have few effects on the pressure distributions over the vane surface. However, they have great influence on prediction of the temperature distributions on the vane surface. The combination of k-${\omega}$ based SST turbulence model, ${\gamma}$ transition model and viscous work term are better than RSM turbulence model on prediction of the surface temperature. The average temperature difference between CFD results and experimental results is calculated 2 % at the pressure side and 1 % at the suction side. Furthermore computing time of this combination is half of the RSM turbulence model. When k-${\omega}$ based SST turbulence model and ${\gamma}$ transition model with viscous work term are applied, more accurate predictions of thermal and internal flow characteristics of high pressure turbine are expected.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.11
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• pp.3041-3053
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• 1995

Cylindrical chokes are used widely as components of hydraulic equipments. The dynamic characteristics between flowrate and pressure drop through the cylindrical chokes were discussed by the frequency characteristics of the chokes. It was assumed no pressure recovery occurred near the downstream of the choke. The pulsating jetflow from the outlet of cylindrical chokes show very complex behaviours which are quite different from the steady jet flow but it's not clarified quantitatively. In order to utilize the chokes as a flowmeter, it is indispensable to discuss the estimation of the dynamics of pressure drop in the downstream jetflow region of cylindrical chokes. In this experimental study, it is clarified that the reattachment length depended on pressure wave is compared with it depended on velocity wave. A pulsating flow is verified by visualization method. In the present study, the flow characteristic variables of laminar pulsating flow are investigated analytically and experimentally in a circular pipe. Characteristic parameters of the ratios of inertia(.PHI.$_{t,1}$) and viscous(.PHI.$_{z,1}$) term to pressure term are introduced to describe the flow pattern of laminar pulsating flow. flow.low.

• Korean Journal of Human Ecology
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• v.16 no.4
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• pp.837-848
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• 2007

The literature suggested that a small reduction in overall blood pressure can have a large effect on overall prevalence of hypertension, and therefore, the affect of taste preferences of the population on salt intake should be considered for long-term blood pressure intervention programs. The purpose of this study is to investigate the influence of salt taste preference and salt taste sensitivity on salt intake behavior as risk factors for high blood pressure. We collected information on blood pressure, diet and lifestyle behaviors, salt taste preference and salt taste sensitivity from 540 respondents from Suseo-dong, Seoul. Salt taste sensitivity was assessed by administering a 1% NaCl solution to the subject's tongue and measuring the perceived intensity on 10 level scale. Salt intake behavior was classified into 3 categories: frequency of high-sodium foods, practice of salt-reducing behavior and frequency of vegetable and fruit intake. Salt taste preference showed a significant relation to the subjects' blood pressure, i.e. subjects with a higher salt preference had higher blood pressure. Salt taste sensitivity did not show a significant relation to blood pressure. However, there was a positive correlation between salt taste preference and salt taste sensitivity. Among the 3 indicators used to measure salt intake behavior, the practice of salt-reducing behavior remained significantly correlated to blood pressure. Moreover, salt-reducing behavior and salt taste preference showed a significant correlation, i.e. people who do not like salty foods tend to practice more salt-reducing behavior, leading to reduced levels in blood pressure. In a population, a small reduction in overall blood pressure can have large effects in overall prevalence of hypertension, in contrast to clinical studies where achievement of an individual's normal blood pressure is emphasized. Therefore, taste preference of the population should be considered for long-term blood pressure intervention programs.

• Journal of Korean Academy of Nursing
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• v.44 no.1
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• pp.21-30
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• 2014

Purpose: This study was conducted to explore the impact of registered nurse/nurses' aid (RN/NA) staffing and turnover rate on inpatient health outcomes in long term care hospitals. Methods: A secondary analysis was done of national data from the Health Insurance Review and Assessment Services including evaluation of long term care hospitals in October-December 2010 and hospital general characteristics in July-September 2010. Final analysis of data from 610 hospitals included RN/NA staffing, turnover rate of nursing staff and 5 patient health outcome indicators. Results: Finding showed that, when variables of organization and community level were controlled, patients per RN was a significant indicator of decline in ADL for patients with dementia, and new pressure ulcer development in the high risk group and worsening of pressure ulcers. Patients per NA was a significant indicator for new pressure ulcer development in the low risk group. Turnover rate was not significant for any variable. Conclusion: To maintain and improve patient health outcomes of ADL and pressure ulcers, policies should be developed to increase the staffing level of RN. Studies are also needed to examine causal relation of NA staffing level, RN staffing level and patient health outcomes with consideration of the details of nursing practice.

• Journal of Welding and Joining
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• v.19 no.1
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• pp.33-39
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• 2001

The welding quality by Gas Tungsten Arc Welding shows very high level, but the welding speed is lower than that of gas metal arc welding. Also, the welding quality by automatic GTAW is variable as the arc characteristics is changed by the consumption of electrode tip. The purpose of this study is to investigate the relation between the properties of tungsten electrode tip and the various arc characteristics at high current region. In this study, the high welding current 200A was applied to the repeated arc start test and long term arcing test using the $\phi$3.2 tungsten electrodes with cone angle 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$sharp tip, and 60$^{\circ}$surface polished (S.P.) sharp tip. It was confirmed that the maximum arc pressure by the initial electrode condition was highest in 45$^{\circ}$sharp tip, and the next in 60$^{\circ}$sharp tip, the last was in 30$^{\circ}$sharp tip and 60$^{\circ}$S.P.. But, the maximum arc pressure after the repeated arc start test and long term arcing test was decreased considerably. But, the maximum arc pressure was highest also in 45$^{\circ}$ sharp tip after the tests, the next was in 30$^{\circ}$sharp tip, and the last was in 60$^{\circ}$sharp tip and 60$^{\circ}$S.P.. The arc start characteristics was the most excellent in 60$^{\circ}$S.P., By long term arcing test, the lanthania included in tungsten electrode was extinguished at tip surface preferentially, therefore the arc characteristics of electrode tip got worse.