• Membrane and Water Treatment
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• 제1권1호
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• pp.83-92
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• 2010

To improve the antifouling characteristics of polypropylene hollow fiber microporous membranes in a submerged membrane-bioreactor for wastewater treatment, the surface-modification was conducted by Ar plasma treatment. Surface hydrophilicity was assessed by water contact angle measurements. The advancing and receding water contact angles reduced after the surface modification, and hysteresis between the advancing and receding water contact angles was enlarged after Ar plasma treatment due to the increased surface roughness after surface plasma treatment. After continuous operation in a submerged membrane-bioreactor for about 55 h, the flux recovery after water cleaning and the flux ratio after fouling were improved by 20.0 and 143.0%, while the reduction of flux was reduced by 28.6% for the surface modified membrane after 1 min Ar plasma treatment, compared to those of the unmodified membrane. Morphological observations showed that the mean membrane pore size after Ar plasma treatment reduced as a result of the deposition of the etched species; after it was used in the submerged membrane-bioreactor, the further decline of the mean membrane pore size was caused by the deposition of foulants. X-ray photoelectron spectroscopy and infrared spectroscopy confirmed that proteins and polysaccharide-like substances were the main foulants in the precipitate.

• Biomaterials and Biomechanics in Bioengineering
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• 제2권2호
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• pp.97-109
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• 2015

A series of amphiphilic graft copolymers were synthesized by varying the number of graft chains and graft chain lengths. The polarity of the hydrophobic graft chain on the copolymers was varied their solution properties. The glass transition temperature of the copolymers was in the low-temperature region, because of the amorphous nature of poly (trimethylene carbonate) (PTMC). The surface morphology of the lyophilized colloid gel had a bundle structure, which was derived from the combination of poly(N-hydroxyethylacrylamide)( poly(HEAA)) and PTMC. The solution properties were evaluated using dynamic light scattering and fluorescence measurements. The particle size of the graft copolymers was about 30-300 nm. The graft copolymers with a higher number of repeating units attributed to the TMC (trimethylene carbonate) component and with a lower macromonomer ratio showed high thermal stability. The critical association concentration was estimated to be between $2.2{\times}10^{-3}$ and $8.9{\times}10^{-2}mg/mL$, using the pyrene-based fluorescence probe technique. These results showed that the hydrophobic chain of the graft copolymer having a long PTMC segment had a low polarity, dependent on the number of repeating units of TMC and the macromonomer composition ratio. These results demonstrated that a higher number of repeating units of TMC, with a lower macromonomer composition, was preferable for molecular encapsulation.

• PNF and Movement
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• 제19권3호
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• pp.311-319
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• 2021

Purpose: The study examined the effects of the proprioceptive neuromuscular facilitation pattern exercise and protein intake on balance, gait ability, and lower extremity muscular strength for sarcopenia in the elderly. Methods: A total of 30 elderly people (65~74years) with sarcopenia were recruited and randomized to Group I (n=10), Group II (n=10), and Group III (n=10). Their balance ability was measured using the functional reach test. Group I performed the proprioceptive neuromuscular facilitation pattern exercise and protein intake. Group II performed the proprioceptive neuromuscular facilitation pattern exercise. Group III performed protein intake. Their gait ability was measured using the Timed Up and Go test. Lower extremity muscular strength was measured using the Five Times Sit to Stand test. Results: As a result of comparison within groups, Group I and Group II showed a significant difference in balance, gait, and lower extremity muscular strength after the experiment (p<0.05), and Group I showed a more effectively significant difference than either Group II or Group III in balance, gait, and lower extremity muscular strength before and after the experiment (p<0.05). Conclusion: This study showed that the proprioceptive neuromuscular facilitation patterns exercise and protein intake was effective in balance, gait ability, and lower extremity muscular strength for sarcopenia in the elderly.

• PNF and Movement
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• 제20권1호
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• pp.41-49
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• 2022

Purpose: The aim of this study was to examine the effects of vibration exercise on balance control ability, gait ability, and depression in the elderly. Methods: A total of 24 elderly subjects were recruited and randomized into an experimental (n = 12) or a control (n = 12) group. The experimental group performed both a vibration and a stabilization exercise, and the control group performed a stabilization exercise alone. Balance ability was measured using the functional reach test (FRT), gait ability was measured using the timed up and go test (TUGT), and depression was measured using the Center for Epidemiologic Studies Depression Scale (CES-D). Results: The experimental and control groups showed significant differences for all pre- and post-experiment FRT, TUGT, and CES-D measurements (p <0.05). In a comparison between the two groups, the experimental group in which vibration exercise was applied showed more significant difference in FRT, TUGT, and CES-D than the control group (p <0.05). Conclusion: This study showed vibration exercise to be effective in balance control ability, gait ability, and depression in the elderly.

• Structural Engineering and Mechanics
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• 제43권6호
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• pp.739-759
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• 2012

The tailoring optimization technique recently developed by the author for improving structural response and energy absorption of composites is extended to sandwich shells using a previously developed zig-zag shell model with hierarchic representation of displacements. The in-plane variation of the stiffness properties of plies and the through-the thickness variation of the core properties are determined solving the Euler-Lagrange equations of an extremal problem in which the strain energy due to out-of-plane strains and stresses is minimised, while that due to their in-plane counterparts is maximised. In this way, the energy stored by unwanted out-of-plane modes involving weak properties is transferred to acceptable in-plane modes. As shown by the numerical applications, the critical interlaminar stress concentrations at the interfaces with the core are consistently reduced without any bending stiffness loss and the strength to debonding of faces from the core is improved. The structural model was recently developed by the author to accurately describe strain energy and interlaminar stresses from the constitutive equations. It a priori fulfills the displacement and stress contact conditions at the interfaces, considers a second order expansion of Lame's coefficients and a hierarchic representation that adapts to the variation of solutions. Its functional d.o.f. are the traditional mid-plane displacements and the shear rotations, so refinement implies no increase of the number of functional d.o.f. Sandwich shells are represented as multilayered shells made of layers with different thickness and material properties, the core being treated as a thick intermediate layer.

• Smart Structures and Systems
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• 제6권2호
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• pp.167-182
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• 2010

An adaptronic strut for machine tools with parallel kinematics for compensation of the influence of geometric errors is introduced. Implemented within the strut is a piezoelectric sensor-actuator unit separated in function. In the first part of this contribution, the functional principle of the strut is presented. For use of one piezoelectric transducer as both, sensor and actuator as so-called self-sensing actuator, the acquisition of the sensing signal while actuating simultaneously using electrical bridge circuits as well as filter properties are examined. In the second part the control concept developed for the adaptronic strut is presented. A co-simulation model of the strut for simulating the controlled multi-body behavior of the strut is set-up. The control design for the strut as a stand-alone system is tested under various external loads. Finally, the strut is implemented into a model of the complete machine tool and the influence of the controlled strut onto the behavior of the machine tool is examined.

• Earthquakes and Structures
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• 제8권5호
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• pp.957-976
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• 2015

Recently, two energy-based response parameters, i.e., the absolute and the relative elastic input energy equivalent velocity, have been receiving a lot of research attention. Several studies, in fact, have demonstrated the potential of these intensity measures in the prediction of the seismic structural response. Although some ground motion prediction equations have been developed for these parameters, they only provide marginal distributions without information about the joint occurrence of the spectral values at different periods. In order to build new prediction models for the two equivalent velocities, a large set of ground motion records is used to calculate the correlation coefficients between the response spectral values corresponding to different periods and components of the ground motion. Then, functional forms adopted in models from the literature are calibrated to fit the obtained data. A new functional form is proposed to improve the predictions of the considered models from the literature. The components of the ground motion considered in this study are the two horizontal ones only. Potential uses of the proposed equations in addition to the prediction of the correlation coefficients of the equivalent velocity spectral values are shown, such as the prediction of derived intensity measures and the development of conditional mean spectra.

• Advances in nano research
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• 제2권2호
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• pp.121-133
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• 2014

Polymer nanocomposites are advanced nanomaterials which exhibit dramatic improvements in various mechanical, thermal and barrier properties as compared with the neat polymer. Polystyrene/ alumina nanocomposites were prepared by an ultrasound-assisted solution casting method at filler loadings ranging from 0.2 to 2% and also at different ultrasonic frequencies, viz. 58 kHz, 192/58 kHz, 430 kHz, 470 kHz and 1 MHz. The composites were subjected to mechanical property tests (tensile and impact tests) and cavitation erosion tests to study the enhancement in functional properties. Filler dispersion in the polymer matrix was observed by SEM analysis. The effect of frequency on filler dispersion in the matrix was studied by SEM analysis and functional property enhancement of the composite material. The composites prepared at dual (high/ low) frequency (192/58 kHz) were found to show better property enhancement at low filler loadings as compared with neat polymer and also with composites prepared without ultrasound, thus reinforcing the finding that ultrasound-assisted synthesis is a promising method for the synthesis of nanocomposites.

• 한국전문물리치료학회지
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• 제19권1호
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• pp.86-93
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• 2012

The purpose of this study was to assess the feasibility of task-oriented arm training for chronic hemiparetic stroke patients. The experimental design in this study was the pre-test and post-test with control group for 4-week intervention. Thirty patients with chronic hemiparetic stroke were recruited from 2 rehabilitation units. The subjects were divided randomly into experimental and control groups. The experimental group conducted task-oriented approach, involving 3 subparts of upper extremity activities, and the control group involved in the general upper extremity exercises. Functional movements of the upper extremities were assessed using clinical measures, including the Fugl-Meyer Assessment-Upper Extremity Section, Box and Block Test, and Action Research Arm Test. The score of Fugl-Meyer Assessment showed greater increases in the experimental group than in the control group after training. The improvement in Box and Block Test between pre-test and post-test measurements was significantly greater after task-oriented arm training compared to general upper extremity exercises. Action Research Arm Test scores also improved after task-oriented arm training compared to exercises in the control group. The task-oriented arm training improves the gross and fine motor activities and encouraging the use of the paretic arm through activity dependent intervention expedites the recovery of functional activities in the upper extremities for chronic hemiparetic stroke.

• Membrane and Water Treatment
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• 제1권3호
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• pp.193-206
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• 2010

Organic fouling and biofouling pose a significant challenge to the membrane filtration process. Photocatalysis-membrane hybrid system is a novel idea for reducing these membranes fouling however, when $TiO_2 photocatalyst nanoparticles are used in suspension, catalyst recovery is not only imposes an extra step on the process but also significantly contributes to increased membrane resistance and reduced permeate flux. In this study, $TiO_2$ photocatalyst has been immobilized by coating on the microfiltration (MF) membrane surface to minimize organic and microbial fouling. Nano-sized $TiO_2$ was first synthesized by a sol-gel method. The synthesized $TiO_2$ was coated on a Poly Vinyl Difluoride (PVDF) membrane (MF) surface using spray coating and dip coating techniques to obtain hybrid functional composite membrane. The characteristics of the synthesized photocatalyst and a functional composite membrane were studied using numerous instruments in terms of physical, chemical and electrical properties. In comparison to the clean PVDF membrane, the $TiO_2$ coated MF membrane was found more effective in removing methylene blue (20%) and E-coli (99%).