This study investigated the effects of axillary crutch length on trunk muscle activity and lumbo-pelvic-hip complex movements during crutch gait. Eleven healthy men participated in this study. The participants performed a three-point gait with optimal, shorter, and longer crutch lengths. Weight-bearing (WB) side was determined as the dominant leg side. The electromyography (EMG) activity of the bilateral rectus abdominis (RA) and erector spinae (ES) muscles and lumbo-pelvic-hip complex movements were monitored using a three-dimensional motion system with wireless surface EMG. Differences in the EMG activity of RA and ES muscles and range of motion (ROM) of lumbar spine, pelvis, and hip among conditions were analyzed using one-way repeated-measures analysis of variance, and a Bonferroni correction was conducted. There was less RA muscle activity on the WB side under the optimal crutch length condition compared with shorter and longer crutch length conditions (p<.05). The EMG activity of the RA muscle on the non-WB side and ES muscle on the WB side were significantly decreased under the optimal crutch length condition compared with shorter crutch length condition (p<.05). No significant differences in the EMG activity of the ES muscle on the non-WB side and ROM of lumbo-pelvic-hip complex were found among conditions (p>.05). These findings indicate that the optimal crutch length improves the trunk muscle efficiency during crutch gait.

The purpose of this study was to compare the immediate effects of upper trapezius muscle stretching in more tensed position (MTP) and less tensed position (LTP) on the change of range of motion (ROM) for neck rotation, and the ROM for conjunct neck motions at end-range of neck rotation toward the painful side in patients with unilateral neck pain. Eighteen patients with unilateral neck pain were recruited for the study's MTP group, and 18 age-, weight- and gender-matched patients with unilateral neck pain were recruited for LTP group. The ROM changes in active neck primary and conjunct motions were measured using a cervical ROM inclinometer in the sitting position. Our results showed that both upper trapezius stretching method in MTP and LTP were significantly effective in increasing the ROM of neck rotation toward painful side in patients with unilateral neck pain. However, a significantly greater increase in the ROM for neck rotation and a further decrease in conjunct neck extension during neck rotation toward the painful side were shown in MTP group, compared to LTP group. The upper trapezius stretching in MTP is useful in increasing the ROM of neck rotation and decreasing the range of conjunct neck extension during neck rotation toward the painful side in patients with unilateral neck pain.

This study examined the effects of a physical therapy program on quality of life (QOL), and neck and shoulder disability in head and neck cancer patients. The program included neck and shoulder range of motion (ROM) exercises, massage, progressive strengthening exercises, and stretching exercises. Sixteen patients who were assigned to an experimental group performed physical therapy for 40 minutes three times a week for eight weeks. Fifteen other patients were assigned to a control group who did not performed the physical therapy program. The European organization for research and treatment of cancer (EORTC QLQ-C30) and head and neck (EORTC QLQ-H&N) instruments, and the Neck Disability Index (NDI) were assessed before and after the rehabilitation program. The 40-minute program consisted of a 10-minute ROM exercise for the neck and shoulder, a 10-minute massage and 15-minute of progressive resistance exercises, followed by a five-minute stretching exercises. Statistically significant differences were noted for changes in global health, physical function in the EORTC QLQ-C30 and cancer related symptoms in the EORTC QLQ-H&N35 (p<.05). The NDI also showed significant differences (p<.05). Physical therapy may therefore benefit the physical aspects and QOL and improve neck and shoulder disability in patients with head and neck cancer.

The purpose of this study was to determine the effects of warm-up and cool-down exercises on pain and muscle activation of delayed onset muscle soreness after intense exercise. Delayed onset muscle soreness was caused by the eccentric exercise in the elbow flexor muscle of the non-dominant upper limb. Forty-four subjects volunteered to participate in this study and were randomly assigned to one of the following groups: warm-up and cool-down group, only warm-up group, only cool-down group, or control group with no intervention. The level of perceived pain using the visual analogue scale and electromyographic activation change in maximal voluntary isometric contraction were measured 4 times at the following times: 10 min, 24 hr, 48 hr, and 72 hr after the exercise. The results revealed the main effect between the groups and interaction effect between the group and measurement session (p<.05). The warm-up and cool-down group showed most favorable results with respect to reduced perceived pain level and increased muscle strength in most measurement sessions, and the only warm-up group showed significantly more decreased pain level than the control group at 24 hr and 48 hr and more increased muscle activation than the cool-down group at 48 hr (p<.05). However, there were no significant differences in pain level and muscle activation between the only cool-down group and control group at all measurement sessions (p>.05). The findings suggest that the warm-up exercise performed before an intense exercise had beneficial effects on the symptoms of delayed onset muscle soreness, whereas cool-down exercise performed after the intense exercise did not.

The purpose of this study was to compare the ring lock type knee-ankle-foot orthosis (KAFO) with newly developed 4-bar linkage KAFO on the gait characteristics of persons with poliomyelitis clinically. This 4-bar linkage is the stance control type KAFO which provide the stability during stance phase and knee flexion during swing phase. Two subjects participated in this study voluntarily. We provided the customized 4-bar linkage KAFO then asked the subjects to walk in level surface and stairs under the two different KAFO conditions. The characteristics of gait in the persons with poliomyelitis were evaluated using a 3D motion analysis system and force plate. Additionally 6 minute walk test for physiological cost index were conducted using pulse oximeter to measure the energy consumption. In the results of this study, the differences of 4-bar linkage KAFO compared with ring lock type KAFO are as follows: (1) Walking speed, stride length, and step length on level increased in subjects, (2) The gait symmetry was improved by generated knee flexion and decreased pelvic external rotation on level and stairs walking, (3) Decreased vertical excursion of center of mass and pelvic elevation during swing phase was decreased on level, (4) Knee extension moment, hip flexion moment, hip and knee internal rotation moment of non-braced limb were decreased on level walking, (5) Walking speed in 6-minute walk test was increased and physiological cost index was decreased. These findings indicate that 4-bar linkage KAFO compared with ring lock type KAFO is effective in enhancing pattern, endurance, and energy consumption in level surface and stairs walking.

The purpose of this study was to assess the influence of the duration of smartphone usage on cervical and lumbar spine flexion angles and reposition error in the cervical spine. The study included 18 healthy smartphone users (7 males and 11 females). We measured the kinematics of the upper and lower cervical and lumbar spine flexion angles and the reposition error of the upper and lower cervical spine after 3 s and 300 s smartphone use in sitting. A paired t-test was used to compare the effects of the duration of smartphone usage on the kinematics of cervical and lumbar spine flexion angles and reposition error. The flexion angles of the lower cervical and lumbar spine and the reposition error in the upper and lower cervical spine were significantly increased after 300 s smartphone of use (p<.05). However, the flexion angle of the upper cervical spine was not significantly different between the 3 s and 300 s smartphone of use (p>.05). These findings suggest that prolonged use of smartphones can induce changes in cervical and lumbar spine posture and proprioception in the cervical spine.

The purpose of this study was to determine the effect of the pelvic compression belt (PCB) on the electromyography (EMG) activities of trunk muscles during sit-to-stand (SitTS), and stand-to-sit (StandTS) tasks. Twenty healthy subjects (7 men and 13 women) were recruited for this study. The subjects performed SitTS, and StandTS tasks, with and without a PCB. Surface EMG was used to record activity of the internal oblique (IO), external oblique (EO), rectus abdominis (RA), erector spinae (ES), and multifidus (MF) of the dominant limb. EMG activity significantly decreased in the RA (without the PCB, %maximal voluntary isometric contraction [%MVIC]; with the PCB, %MVIC), EO (without the PCB, %MVIC; with the PCB, %MVIC), MF (without the PCB, %MVIC; with the PCB, %MVIC), and ES (without the PCB, %MVIC; with the PCB, %MVIC) during the SitTS task and in the IO (without the PCB, %MVIC; with the PCB, %MVIlC), RA (without the PCB, %MVIC; with the PCB, %MVIC), EO (without the PCB, %MVIC; with the PCB, %MVIC), MF (without the PCB, %MVIC; with the PCB, %MVIC), and ES (without the PCB, %MVIC; with the PCB, %MVIC) during the StandTS task when a PCB was used (p<.05). In men the EMG activity of the MF significantly decreased during the SitTS task when a PCB was used (p<.05): in women, the EMG activity of the RA, EO, MF, and ES during the SitTS task and that of the EO, MF, and ES during the SitTS task significantly decreased when a PCB was used (p<.05). In addition, the rates of change in the EMG activity of each muscle differed significantly during the SitTS and StandTS tasks before and after the use of the PCB. However, the EMG activity did not significantly differ between the male and female subjects. These findings suggest that the PCB may contribute to the modification of activation patterns of the trunk muscles during SitTS, and StandTS tasks.

Recently, consumption of magnesium alloys has increased especially in the 3C (computer, communication, camera) and automobile industries. The structural application of magnesium alloys has many advantages due to their low densities, high specific strength, excellent damping and anti-eletromagnetic properties, and easy recycling. However, practical application of these alloys has been limited to narrow uses of mild condition, because they are inferior in corrosion resistance and wear resistance due to their high chemical reactivity and low hardness. Various wet and dry processes are being used or are under development to enhance alloy surface properties. Various conversion coating and anodizing methods have been developed in a view of eco-friendly concept. The conventional technologies, such as diffusion coating, sol-gel coating, hydrothermal treatment, and organic coating, are expected to be newly applicable to magnesium alloys. Surface treatments for metallic luster or coloring are suggested using the control of the micro roughness. This report reviews the recent R&D trends and achievements in surface treatment technologies for magnesium alloys.

Porous Al2O3 dispersed with nano-sized Cu was fabricated by freeze-drying process and solution chemistry method using Cu-nitrate. To prepare porous Al2O3, camphene was used as the sublimable vehicle. Camphene slurries with Al2O3 content of 10 vol% were prepared by milling at 50˚C with a small amount of oligomeric polyester dispersant. Freezing of the slurry was done in a Teflon cylinder attached to a copper bottom plate cooled to -25˚C while unidirectionally controlling the growth direction of the camphene. Pores were subsequently generated by sublimation of the camphene during drying in air for 48 h. The green body was sintered in a furnace at 1400˚C for 1 h. Cu particles were dispersed in porous Al2O3 by calcination and hydrogen reduction of Cu-nitrate. The sintered samples showed large pores with sizes of about 150μm; these pores were aligned parallel to the camphene growth direction. Also, the internal walls of the large pores had relatively small pores due to the traces of camphene left between the concentrated Al2O3 particles on the internal wall. EDS analysis revealed that the Cu particles were mainly dispersed on the surfaces of the large pores. These results strongly suggest that porous Al2O3 with Cu dispersion can be successfully fabricated by freeze-drying and solution chemistry routes.

Opal glass samples having different chemical compositions were synthesized and transparent glass was obtained after melting. The effects of TiO2, BaF2, and CeO2 content on the color of the opal glass were studied by observing images of the opal samples and analyzing the results via ultraviolet visible spectroscopy and color spectrometry. The aesthetic properties of the opal glass were determined by studying the transmittance of visible light in the 400 nm to 700 nm range. The basic chemical composition of opal glass was SiO2 52.9 wt%, Al2O3 12.35 wt%, Na2CO3 15.08 wt%, K2CO3 10.35 wt%, Ca3(PO)4 4.41 wt%, MgCO3 1.844 wt%, LiCO3 2.184 wt%, and TiO2 0.882 wt%. The glass samples were prepared by varying the weight percentage of TiO2, BaF2, and CeO2. The transmittance of visible light was decreased from 95 % to 75 % in the glass samples in which TiO2 content was increased from 0 to 3.882 wt%. In the blue spectrum region, as the content of TiO2 increased, the reflectance value was observed to become higher. This implies that TiO2 content induces more crystal formation and has an important effect on the optical properties of the glass. The opalescence of opal samples that contained CeO2 or BaF2 is stronger than that in the samples containing TiO2. Opal glass samples comprising TiO2 had tetragonal lattice structures; samples including CeO2 as an additive had cubic lattice structures (FCC, CeO2).

Superhydrophobic SiO2 layers with a micro-nano hierarchical surface structure were prepared. SiO2 layers depositedvia an electrospray method combined with a sol-gel chemical route were rough on the microscale. Au particles were decoratedon the surface of the microscale-rough SiO2 layers by use of the photo-reduction process with different intensities (0.11-1.9 mW/cm2) and illumination times (60-240 sec) of ultraviolet light. With the aid of nanoscale Au nanoparticles, this consequentlyresulted in a micro-nano hierarchical surface structure. Subsequent fluorination treatment with a solution containingtrichloro(1H,2H,2H,2H-perfluorooctyl)silane fluorinated the hierarchical SiO2 layers. The change in surface roughness factorwas in good agreement with that observed for the water contact angle, where the surface roughness factor developed as ameasure needed to evaluate the degree of surface roughness. The resulting SiO2 layers revealed excellent repellency towardvarious liquid droplets with different surface tensions ranging from 46 to 72.3mN/m. Especially, the micro-nano hierarchicalsurface created at an illumination intensity of 0.11mW/cm2 and illumination time of 60 sec showed the largest water contactangle of 170o. Based on the Cassie-Baxter and Young-Dupre equations, the surface fraction and work of adhesion for the micro-nano hierarchical SiO2 layers were evaluated. The work of adhesion was estimated to be less than 3×10−3N/m for all the liquiddroplets. This exceptionally small work of adhesion is likely to be responsible for the strong repellency of the liquids to themicro-nano hierarchical SiO2 layers.

Graphene has been synthesized on 100- and 300-nm-thick Ni/SiO2/Si substrates with CH4 gas (1 SCCM) diluted in mixed gases of 10% H2 and 90% Ar (99 SCCM) at 900˚C by using inductively-coupled plasma chemical vapor deposition (ICP-CVD). The film morphology of 100-nm-thick Ni changed to islands on SiO2/Si substrate after heat treatment at 900˚C for 2 min because of grain growth, whereas 300-nm-thick Ni still maintained a film morphology. Interestingly, suspended graphene was formed among Ni islands on 100-nm-thick Ni/SiO2/Si substrate for the very short growth of 1 sec. In addition, the size of the graphene domains was much larger than that of Ni grains of 300-nm-thick Ni/SiO2/Si substrate. These results suggest that graphene growth is strongly governed by the direct formation of graphene on the Ni surface due to reactive carbon radicals highly activated by ICP, rather than to well-known carbon precipitation from carbon-containing Ni. The D peak intensity of the Raman spectrum of graphene on 300-nm-thick Ni/SiO2/Si was negligible, suggesting that high-quality graphene was formed. The 2D to G peak intensity ratio and the full-width at half maximum of the 2D peak were approximately 2.6 and 47cm-1, respectively. The several-layer graphene showed a low sheet resistance value of 718Ω/sq and a high light transmittance of 87% at 550 nm.

The microstructural evolution of AA1050/AA6061 complex aluminum alloy, which is fabricated using an accumulative roll-bonding (ARB) process, with the proceeding of ARB, was investigated by electron back scatter diffraction (EBSD) analysis. The specimen after one cycle exhibited a deformed structure in which the grains were elongated to the rolling direction for all regions in the thickness direction. With the proceeding of the ARB, the grain became finer; the average grain size of the as received material was 45μm; however, it became 6.3μm after one cycle, 1.5μm after three cycles, and 0.95μm after five cycles. The deviation of the grain size distribution of the ARB processed specimens decreased with increasing number of ARB cycles. The volume fraction of the high angle grain boundary also increased with the number of ARB cycles; it was 43.7% after one cycle, 62.7% after three cycles, and 65.6% after five cycles. On the other hand, the texture development was different depending on the regions and the materials. A shear texture component 001<110> mainly developed in the surface region, while the rolling texture components 011<211> and 112<111> developed in the other regions. The difference of the texture between AA1050 and AA6061 was most obvious in the surface region; 001<110> component mainly developed in AA1050 and 111<110> component in AA6061.

In this study, the influence on the surface passivation properties of crystalline silicon according to silicon wafer thickness, and the correlation with a-Si:H/c-Si heterojunction solar cell performances were investigated. The wafers passivated by p(n)-doped a-Si:H layers show poor passivation properties because of the doping elements, such as boron(B) and phosphorous(P), which result in a low minority carrier lifetime (MCLT). A decrease in open circuit voltage (Voc) was observed when the wafer thickness was thinned from 170μm to 50μm. On the other hand, wafers incorporating intrinsic (i) a-Si:H as a passivation layer showed high quality passivation of a-Si:H/c-Si. The implied Voc of the ITO/p a-Si:H/i a-Si:H/n c-Si wafer/i a-Si:H/n a-Si:H/ITO stacked layers was 0.715 V for 50μm c-Si substrate, and 0.704 V for 170μm c-Si. The Voc in the heterojunction solar cells increased with decreases in the substrate thickness. The high quality passivation property on the c-Si led to an increasing of Voc in the thinner wafer. Short circuit current decreased as the substrate became thinner because of the low optical absorption for long wavelength light. In this paper, we show that high quality passivation of c-Si plays a role in heterojunction solar cells and is important in the development of thinner wafer technology.

Trivalent cerium-ion-doped Y3(Al, Ga)5O12 nanoparticle phosphor nanoparticles were synthesized using the reversemicelle process. The Ce doped Y3(Al, Ga)5O12 particles were obtained from nitrate solutions dispersed in the nanosized aqueousdomains of a micro emulsion consisting of cyclohexane as the oil phase and poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant. The crystallinity, morphology, and thermal properties of the synthesized Y3(Al, Ga)5O12:Ce3+powders were characterized by thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD),scanning electron microscopy (SEM), and transmission electron microscopy. The crystallinity, morphology, and chemical statesof the ions were characterized; the photo-physical properties were studied by taking absorption, excitation, and emission spectrafor various concentrations of cerium. The photo physical properties of the synthesized Y3(Al, Ga)5O12:Ce3+ powders werestudied by taking the excitation and emission spectra for various concentrations of cerium. The average particle size of thesynthesized YAG powders was below 1µm. Excitation spectra of the Y3Al5O12 and Y3Al3.97Ga1.03O12 samples were 485nmand 475nm, respectively. The emission spectra of the Y3Al5O12 and Y3Al3.97Ga1.03O12 were around 560nm and 545nm,respectively. Y3(Al, Ga)5O12:Ce3+ is a red-emitting phosphor; it has a high efficiency for operation under near UV excitation,and may be a promising candidate for photonic applications.

Today, the modification of carbon foam for high performance remains a major issue in the environment and energy industries. One promising way to solve this problem is the optimization of the pore structure for desired properties as well as for efficient performance. In this study, using a sol-gel process followed by carbonization in an inert atmosphere, hollow spherical carbon foam was prepared using resorcinol and formaldehyde precursors catalyzed by 4-aminobenzoic acid; the effect of carbonization temperature and re-immersion treatment on the pore structure and characteristics of the hollow spherical carbon foam was investigated. As the carbonization temperature increased, the porosity and average pore diameter were found to decrease but the compression strength and electrical conductivity dramatically increased in the temperature range of this study (700˚C to 850˚C). The significant differences of X-ray diffraction patterns obtained from the carbon foams carbonized under different temperatures implied that the degree of crystallinity greatly affects the characteristics of the carbon form. Also, the number of re-impregnations of carbon form in the resorcinol-formaldehyde resin was varied from 1 to 10 times, followed by re-carbonization at 800˚C for 2 hours under argon gas flow. As the number of re-immersion treatments increased, the porosity decreased while the compression strength improved by about four times when re-impregnation was repeated 10 times. These results imply the possibility of customizing the characteristics of carbon foam by controlling the carbonization and re-immersion conditions.

In this study, the effects of cryogenic treatment cycles on the residual stress and mechanical properties of 7075 aluminum alloy (Al7075) samples, in the form of a tube-shaped product with a diameter of 500 nm, were investigated. Samples were first subjected to solution treatment at 470˚C, followed by cryogenic treatment and aging treatment. The residual stress and mechanical properties of the samples were systematically characterized. Residual stress was measured with a cutting method using strain gauges attached on the surface of the samples; in addition, tensile strength and Vickers hardness tests were performed. The detailed microstructure of the samples was investigated by transmission electron microscopy. Results showed that samples with 85 % relief in residual stress and 8% increase in tensile strength were achieved after undergoing three cycles of cryogenic treatments; this is in contrast to the samples processed by conventional solution treatment and natural aging (T4). The major reasons for the smaller residual stress and relatively high tensile strength for the samples fabricated by cryogenic treatment are the formation of very small-sized precipitates and the relaxation of residual stress during the low temperature process in uphill quenching. In addition, samples subjected to three cycles of cryogenic treatment demonstrated much lower residual stress than, and similar tensile strength compared to, those samples subjected to one cycle of cryogenic treatment or artificial aging treatment.

The alignments of polystyrene particles of 1μm and 5μm sizes in an aqueous colloidal system were observed by varying the electric field strength, the frequency and the water flow. Spherical mono-dispersed polystyrene particles dispersed in pure water were put into a perfusion chamber; an AC electric field was applied to the Au/Cr electrodes with a 4 mm gap on the glass substrate. The mixture of the 1μm and 5μm sized polystyrene particles at 0.5 vol% concentrations for each size was set in the dielectrophoresis conditions of 1 kHz and 150 V/cm. Large particles of 5μm size were aligned to form chains as the result of the dielectrophoresis force interaction. On the contrary, small particles of 1μm size did not form chains because the dielectrophoresis force was not sufficiently large. When the electric field increased to 250 V/cm, small particles were able to form chains. After the chains were formed from both large and small particles, they began to coalescence as time passed. Owing to the electroosmotic flow of water, wave patterns along the perpendicular direction of the applied electric field appeared at the conditions of 200 Hz and 50 V/cm, when the dielectrophoresis force was small. This wave pattern also appeared for small particles at 1 kHz and 150 V/cm conditions due to the flow of solvent when water was forced to circulate.

The Cu2ZnSnS4 (CZTS) thin film solar cell is a candidate next generation thin film solar cell. For the application of an absorption layer in solar cells, CZTS thin films were deposited by pulsed laser deposition (PLD) at substrate temperature of 300˚C without post annealing process. Deposition time was carefully adjusted as the main experimental variable. Regardless of deposition time, single phase CZTS thin films are obtained with no existence of secondary phases. Irregularly-shaped grains are densely formed on the surface of CZTS thin films. With increasing deposition time, the grain size increases and the thickness of the CZTS thin films increases from 0.16 to 1μm. The variation of the surface morphology and thickness of the CZTS thin films depends on the deposition time. The stoichiometry of all CZTS thin films shows a Cu-rich and S-poor state. Sn content gradually increases as deposition time increases. Secondary ion mass spectrometry was carried out to evaluate the elemental depth distribution in CZTS thin films. The optimal deposition time to grow CZTS thin films is 150 min. In this study, we show the effect of deposition time on the structural properties of CZTS thin film deposited on soda lime glass (SLG) substrate using PLD. We present a comprehensive evaluation of CZTS thin films.

A simple thermal oxidation of Cu thin films deposited on planar substrates established a growth of vertically aligned copper oxide (CuO) nanorods. DC sputter-deposited Cu thin films with various thicknesses were oxidized in environments of various oxygen partial pressures to control the kinetics of oxidation. This is a method to synthesize vertically aligned CuO nanorods in a relatively shorter time and at a lower cost than those of other methods such as the popular hydrothermal synthesis. Also, this is a method that does not require a catalyst to synthesize CuO nanorods. The grown CuO nanorods had diameters of ~100 nm and lengths of 1~25μm. We examined the morphology of the synthesized CuO nanorods as a function of the thickness of the Cu films, the gas environment, the oxidation time, the oxidation temperature, the oxygen gas flow rate, etc. The parameters all influence the kinetics of the oxidation, and consequently, the volume expansion in the films. Patterned growth was also carried out to confirm the hypothesis of the CuO nanorod protrusion and growth mechanism. It was found that the compressive stress built up in the Cu film while oxygen molecules incorporated into the film drove CuO nanorods out of the film.