The microstructural evolution and modulation of mechanical properties were investigated for a Ti65Fe35 hypereutectic alloy by addition of Bi53In47 eutectic alloys. The microstructure of these alloys changed with the additional Bi- In elements from a typical dendrite-eutectic composite to a bimodal eutectic structure with primary dendrite phases. In particular, the primary dendrite phase changed from a TiFe intermetallic compound into a β-Ti solid solution despite their higher Fe content. Compressive tests at room temperature demonstrated that the yield strength slightly decreased but the plasticity evidently increased with an increasing Bi-In content, which led to the formation of a bimodal eutectic structure (β-Ti/TiFe + β- Ti/BiIn containing phase). Furthermore, the (Ti65Fe35)95(Bi53In47)5 alloy exhibited optimized mechanical properties with high strength (1319MPa) and reasonable plasticity (14.2%). The results of this study indicate that the transition of the eutectic structure, the type of primary phases and the supersaturation in the β-Ti phase are crucial factors for controlling the mechanical properties of the ultrafine dendrite-eutectic composites.

Evaluation of the durability and stability of materials used in power plants is of great importance because parts or components for turbines, heat exchangers and compressors are often exposed to extreme environments such as high temperature and pressure. In this work, high-temperature corrosion behavior of 316 L stainless steel in a carbon dioxide environment was studied to examine the applicability of a material for a supercritical carbon dioxide Brayton cycle as the next generation power plant system. The specimens were exposed in a high-purity carbon dioxide environment at temperatures ranging from 500 to 800 oC during 1000 hours. The features of the corroded products were examined by optical microscope and scanning electron microscope, and the chemical compound was determined by x-ray photoelectron spectroscopy. The results show that while the 316 L stainless steel had good corrosion resistance in the range of 500-700 oC in the carbon dioxide environment, the corrosion resistance at 800 oC was very poor due to chipping the corroded products off, which resulted in a considerable loss in weight.

In order to develop a new commercial Al-12%Si casting alloy with improved physical properties, we investigated the effect of adding Sr and TiB to the alloy. Al-12%Si alloys were prepared by die casting at 660 oC. The eutectic temperature of the Sr-modified Al-12%Si alloy decreased to 9 oC and the mushy zone region increased. The shape of the Si phase changed from coarse acicula to fine fiber with the addition of Sr. The addition of TiB in the Al-12%Si alloy reduced the size of the primary α-Al and eutectic Si phases. When Sr and TiB were added together, it worked more effectively in refinement and modification. The density of twins in the Si phase-doped Sr increased and the width of the twins was refined to 5 nm. These results are related to the impurity induced twinning(IIT) growth.

Gd2O3:Eu3+ red phosphors were prepared by template method from crystalline cellulose impregnated by metal salt. The crystallite size and photoluminescence(PL) property of Gd2O3:Eu3+ red phosphors were controlled by varying the calcination temperature and Eu3+ mol ratio. The nano dispersion of Gd2O3:Eu3+ was also conducted with a bead mill wet process. Dependent on the time of bead milling, Gd2O3:Eu3+ nanosol of around 100 nm (median particle size : D50) was produced. As the bead milling process proceeded, the luminescent efficiency decreased due to the low crystallinity of the Gd2O3:Eu3+ nanoparticles. In spite of the low PL property of Gd2O3:Eu3+ nanosol, it was observed that the photoluminescent property was recovered after re-calcination. In addition, in the dispersed nanosol treated at 85 oC, a self assembly phenomenon between particles appeared, and the particles changed from spherical to rod-shaped. These results indicate that particle growth occurs due to mutual assembly of Gd(OH)3 particles, which is the hydration of Gd2O3 particles, in aqueous solvent at 85 oC.

ZnO micro/nanocrystals with different morphologies were synthesized by thermal evaporation of various zinc source materials in an air atmosphere. Zinc acetate, zinc carbonate and zinc iodide were used as the source materials. No catalysts or substrates were used in the synthesis of the ZnO crystals. The scanning electron microscope(SEM) image showed that the morphology of ZnO crystals was strongly dependent on the source materials, which suggests that source material is one of the key factors in controlling the morphology of the obtained ZnO crystals. Tetrapods, nanogranular shaped crystals, spherical particles and crayon-shaped crystals were obtained using different source materials. The X-ray diffraction(XRD) pattern revealed that the all the ZnO crystals had hexagonal wurtzite crystalline structures. An ultraviolet emission was observed in the cathodoluminescence spectrum of the ZnO crystals prepared via thermal evaporation of Zn powder. However, a strong green emission centered at around 500 nm was observed in the cathodoluminescence spectra of the ZnO crystals prepared using zinc salts as the source materials.

The effect of strain aging on the tensile properties of API X70 linepipe steel was investigated in this study. The API X70 linepipe steel was fabricated by controlled rolling and accelerated cooling processes, and the microstructure was analyzed using optical and scanning electron microscopes and electron backscatter diffraction. Strain aging tests consisting of 1% pre-strain and thermal aging at 200 oC and 250 oC were conducted to simulate U-forming, O-forming, Expansion(UOE) pipe forming and anti-corrosion coating processes. The API X70 linepipe steel was composed of polygonal ferrite, acicular ferrite, granular bainite, and bainitic ferrite whose volume fraction was dependent on the chemical composition and process conditions. As the thermal aging temperature increased, the steel specimens showed more clearly discontinuous type yielding behavior in the tensile stress-strain curve due to the formation of a Cottrell atmosphere. After pre-strain and thermal aging, the yield and tensile strengths increased and the yield-to-tensile strength ratio decreased because yielding and aging behaviors significantly affected work hardening. On the other hand, uniform and total elongations decreased after pre-strain and thermal aging since dislocation gliding was restricted by increased dislocation density after a 1% pre-strain.

In commercial solar cells, the pattern of the front electrode is critical to effectively assemble the photo generated current. The power loss in solar cells caused by the front electrode was categorized as four types. First, losses due to the metallic resistance of the electrode. Second, losses due to the contact resistance of the electrode and emitter. Third, losses due to the emitter resistance when current flows through the emitter. Fourth, losses due to the shading effect of the front metal electrode, which has a high reflectance. In this paper, optimizing the number of finger on a 4 ´ 4 solar cell is demonstrated with known theory. We compared the short circuit current density and fill factor to evaluate the power loss from the front metal contact calculation result. By experiment, the short circuit current density(Jsc), taken in each pattern as 37.61, 37.53, and 37.38 mA/ cm2 decreased as the number of fingers increased. The fill factor(FF), measured in each pattern as 0.7745, 0.7782 and 0.7843 increased as number of fingers increased. The results suggested that the efficiency(Eff) was measured in each pattern as 17.51, 17.81, and 17.84 %. Throughout this study, the short-circuit current densities(Jsc) and fill factor(FF) varied according to the number of fingers in the front metal pattern. The effects on the efficiency of the two factors were also investigated.

An optimum route to fabricate a hybrid-structured W powder composed of nano and micro size powders was investigated. The mixture of nano and micro W powders was prepared by a ball milling and hydrogen reduction process for WO3 and W powders. Microstructural observation for the ball-milled powder mixtures revealed that the nano-sized WO3 particles were homogeneously distributed on the surface of large W powders. The reduction behavior of WO3 powder was analyzed by a temperature programmed reduction method with different heating rates in Ar-10% H2 atmosphere. The activation energies for the reduction of WO3, estimated by the slope of the Kissinger plot from the amount of reaction peak shift with heating rates, were measured as 117.4 kJ/mol and 94.6 kJ/mol depending on reduction steps from WO3 to WO2 and from WO2 to W, respectively. SEM and XRD analysis for the hydrogen-reduced powder mixture showed that the nano-sized W particles were well distributed on the surface of the micro-sized W powders.

The purpose of this study was to investigate the effects of central posteroanterior mobilization on the pain, muscle tone, flexibility of trunk flexion, lumbar lordosis in patient with chronic back pain has been studied. The target subject was a 23 year old man, who had chronic back pain without surgical history within six months. The pain has been indicated by the pressure pain threshold, when the subject was pressed his spinous process of L3-L1 by the pressure of grade Ⅳ. The muscle tone, elasticity, and stiffness were measured by the MYOTONEⓇ PRO, and the flexibility of trunk flexion was evaluated by the distance from the figure tips to the floor, when subjects flexed their body. The lumbar lordosis was measured from the X-ray picture. The lumbar central posteroanterior mobilization of Maitland orthopedic physical therapy has been applied to the spinous process of L3-L1 in grade Ⅳ by five sets and 10 times for each set. According to the measurement result right after the intervention, the pain decreased from 2/10 to 1/10 based on the visual analogue scale. The flexibility of trunk flexion (distance from the finger tips to the floor) increased The muscle tone decreased from 15.3 to 14.65 and the muscle stiffness also decreased 53.5 from 310 to 256.5. However, the muscle elasticity increased from 0.89 to 1.04 and there was no changed on the lumbar lordosis as 25°. The results of the present study suggest that the central posteroanterior mobilization decrease the pain, muscle tone, and muscle stiffness of the lumbar area, however increase the muscle elasticity and flexibility of the trunk flexion.

This study aims to identify the effects of extracorporeal shock wave therapy and stretching technique on flexibility, muscle tone and pressure pain threshold of a shortened hamstring. A total of 40 patients with hamstring shortening was randomly assigned to either the extracorporeal shock wave therapy group (n=20) or extracorporeal shock wave therapy with stretching technique group (n=20) to identify the effects of the two different forms of physical therapy intervention. All the participants underwent extracorporeal shockwave therapy twice a week for 3 weeks, and the extracorporeal shockwave therapy with stretching technique group performed stretching techniques with the same frequency for 3 weeks. To measure hamstring flexibility before and after intervention, the passive straight leg raising test was performed, and muscle tone and pressure pain threshold were assessed. The flexibility of the hamstrings significantly improved, while the pressure pain threshold increased in both groups. These findings suggest that the effective in improving hamstring flexibility, reducing muscle tone, and increasing pressure pain threshold in adults with hamstring shortening.

The aim of this study was to analyze the effect of task-oriented progressive resistance strength training and functional electrical stimulation (FES) on the gait speed and activity of daily living (ADL) in stroke patients. Twenty one patients diagnosed with stroke were randomly divided into 3 groups: the task-oriented progressive resistance strength training group (TPRSTG, n=7), the task-oriented progressive resistance strength training with FES group (TPRSTFESG, n=7), and the control group (CG, n=7). The length of intervention for each session in all groups was 30 minutes, and was performed once a day, 5 times a week, for a total of 6 weeks. The gait speed was measured using 10m walking velocity Test (10MWT) and the ADL was measured using the functional independence measure (FIM). TPRSTFESG demonstrated the most statistically significant lapse in 10MWT (p<.05). While post-intervention analysis showed a significant difference in ADL (p<.05), further analysis between each group indicated that there were no statistically significant differences between the groups post-intervention. These findings suggest that application of both task-oriented progressive resistance strength training with FES is the most effective intervention in improving gait speed.

The aim this study was to examine the effect of general squat and wall squat exercises on the muscle activity of the vastus medialis oblique (VMO) and vastus lateralis (VL), and the muscle activity of the VMO and VL during squat exercises depending on the flexion angle of the knee joint. Thirty adults in their 20s participated in the study, and subjects were divided into the general squat group, and the wall squat group, and their electromyographic (EMG) was monitored and collected during squat exercises. The muscle activity of the VL during squat exercises was compared between the two groups, and that of the wall squat group was higher than that of the general squat group, indicate a statistically significant difference (p<.05). The muscle activity of the VMO of the wall squat group was also higher than that of the general squat group, indicate a statistically significant difference (p<.05). The muscle activity depending on the angle of the knee joint was compared between the two groups, and that of the VL showed a statistically significant difference between different angles of the knee joint (p<.05). That of the VMO also showed a statistically significant difference between different angles of the knee joint (p<.05). The findings of the present study suggest that wall squat is more effective in improving the muscular strength of the VL and VMO than general squat, and that maintaining the angle of the knee joint at 60° is more effective in improving the muscular strength than maintaining it at 15° or 45°

The aim of the present study was to investigate the effects of unilateral shoulder bag weight and heel heights on trunk muscle activities. This study recruited 40 healthy women in their twenties. Electromyography activities of rectus abdominis muscle, external abdominal oblique muscle, internal abdominal oblique muscle and erector spinae muscle during standing position were measured using a surface electromyography system. The overall muscle activities of the trunk muscles were significantly increased in the contralateral trunk muscles (p<.05). Inaddition, the trunk muscles overall activities on the contralateral side without the shoulder bag was positive correlation with the heel height and unilateral shoulder bag weight (p<.05). Both high-heeled wear and unilateral shoulder bags are fashion items that cause asymmetry in the trunk muscles of women in their twenties. These findings suggest that the increase in the weight and heel height of the unilateral shoulder bag in women cause asymmetry of trunk muscle activities.

This study aimed to identify the effects of modified low-dye taping and foot intrinsic muscle strengthening exercise on foot pressure in people with flat feet. The subjects were 12 participants with flat feet in their 20s. They were randomly divided into two groups: taping and strengthening exercise. They performed the interventions twice a week for six weeks. The taping group was applied the modified low-dye taping. The exercise group was performed foot intrinsic muscle strengthening exercise for 30 minutes. The data were measured by Foot Pressure Measurement. There was no significant difference in plantar pressure between taping group and exercise group. There was also no significant difference in all variables before and after intervention in all groups. The present study suggests that taping and exercise can change the foot pressure in patients with flat-footed.

The purpose of the study was to determine the effect of joint mobilization with respiratory muscle taping on pulmonary function and chest expansion ability in patients with chronic stroke. Thirty subjects (n=30) were randomly divided into three groups: a joint mobilization group (n=10), a respiratory muscle-taping group (n=10), and a joint mobilization with respiratory muscle-taping group (n=10). Measurements for pulmonary function and chest expansion were performed to assess its effectiveness. A spirometer was used to measure the pulmonary function, and a tape measure was used to assess the chest expansion. In the joint mobilization group, peak expiratory flow (PEF) was increased. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and upper and lower chest expansion were also increased. All of variables of respiratory muscle-taping group also were increased. FEV1 and FVC were significantly different between joint mobilization with respiratory muscle-taping and respiratory muscle-taping group. The results of the present study suggest that mobilization with respiratory muscle taping increase the pulmonary function and chest expansion.

The aim of the present study was to compare the effects of Rolfing and Swedish massage. In total, 105 patients with cervical myofascial pain syndrome were divided into two groups based on the intervention: a 40-min Rolfing session (n = 52) or a 40-min Swedish massage session (n = 53). Pre- and pos-tintervention visual analog scale (VAS) scores for pain, muscle tone (Myoton F), muscle elasticity (Myoton D), and muscle stiffness (Myoton S) were measured to compare treatment effects between the two groups. The results revealed a significant decrease in the VAS score for pain, Myoton F, and Myoton S (p < .05), with no change in Myoton D (p > .05), after the intervention in the Rolfing group. Similar findings were obtained for the Swedish massage group. Intergroup comparison of the degree of improvement after the intervention revealed no significant difference for any variable. The findings suggest that both group indicated a similar decrease in pain, muscle tension, and muscle stiffness after the intervention, with no significant improvement in muscle elasticity.

The purpose of this study was to investigate the effects of lumbar stabilization and sling exercise on visual analogue scale (VAS), Korean Oswestry Disability Index (KODI), and stability index (ST) in patients with chronic lower back pain (CLBP). This study included participants with a VAS scale of 6 or higher and a KOD of 20-40%. They were randomly divided into a mat group (n=15) to perform lumbar stabilization exercises and a sling group (n=15) to perform sling exercises, and then they underwent a four-week experiment. The experimental results of this study were as follows: the VAS and KODI showed a statistically significant difference (P<.05) and a larger effect size within each group after the intervention, it exhibited no statistically significant difference between the two groups (P>.05). There were significant differences in ST before and after intervention in each group (P<.05), however there was no significant difference between the groups. The present study suggest that the effects of lumbar stabilization exercise and sling exercise are similar.

The purpose of this study was to examine the effects of abdominal hollowing with ultrasound biofeedback on multifidus and transversus abdominis/internal oblique muscle activities during lifting tasks. This study recruited 12 healthy men. All subjects received training on expiration without and with abdominal hollowing with ultrasound biofeedback. After receiving training for each condition, the thickness of transversus abdominis was measured using ultrasound, and then, electromyography activities of transversus abdominis/internal oblique and multifidus during lifting tasks were measured using a surface electromyography system. The differences in thickness of transversus abdominis and electromyography activities of transversus abdominis/ internal oblique and multifidus between the two conditions were analyzed using paired t-test. Thickness of transversus abdominis and transversus abdominis/internal oblique and multifidus activities were significantly increased during expiration with abdominal hollowing with ultrasound biofeedback compared to during expiration without abdominal hollowing (p < 0.05). These findings suggest that abdominal hollowing with ultrasound biofeedback is effective in increasing trunk stabilizer muscle activities during both static and dynamic tasks such as lifting.

The purpose of this study was to identify the immediate effects of Maitland joint mobilization with kinematic taping in subacromial impingement syndrome patients. The Maitland joint mobilization was applied glenohumeral joint. The mobilization was performed at the end of rage to Grade IV. After that, kinematic tape was attached to shoulder joint (supraspinatis, infraspinatis, and trapezius muscles). The intervention period was four days. The measurement was done five times. The shoulder pain, range of motion (flexion, abduction, and rotation of the shoulder joint), muscle tone and stiffness (upper trapezius and deltoid muscle) were measured. The shoulder pain decreased. The range of motion (ROM) was increased all flexion, abduction, and rotation of the shoulder joint. Muscle tone and stiffness were decreased, especially upper trapezius of those was greatly decreased. The findings of present study suggest that Maitland joint mobilization with kinematic taping is effective in decreasing pain, muscle tone and stiffness, and in increasing shoulder ROM in patients with subacromial impingement syndrome.

An optimum route to fabricate oxide dispersion strengthened ferritic superalloy with desired microstructure was investigated. Two methods of high energy ball milling or polymeric additive solution route for developing a uniform dispersion of Y2O3 particles in Fe-Cr-Al-Ti alloy powders were compared on the basis of the resulting microstructures. Microstructural observation revealed that the crystalline size of Fe decreased with increases in milling time, to values of about 15-20 nm, and that an FeCr alloy phase was formed. SEM and TEM analyses of the alloy powders fabricated by solution route using yttrium nitrate and polyvinyl alcohol showed that the nano-sized Y-oxide particles were well distributed in the Fe based alloy powders. The prepared powders were sintered at 1000 and 1100 oC for 30 min in vacuum. The sintered specimen with heat treatment before spark plasma sintering at 1100 oC showed a more homogeneous microstructure. In the case of sintering at 1100 oC, the alloys exhibited densified microstructure and the formation of large reaction phases due to oxidation of Al.