Red-emitting Eu3+-activated (Y0.95-xAlx)VO4 (0<x≤0.12) nanophosphors with the particle size of ~30nm and thehigh crystallinity have been successfully synthesized by a hydrothermal reaction. In the synthetic process, deionized water asa solvent and ethylene glycol as a capping agent were used. The crystalline phase, particle morphology, and thephotoluminescence properties of the excitation spectrum, emission intensity, color coordinates and decay time, of the prepared(Y0.95-xAlx)VO4:Eu3+ nanophosphors were compared with those of the YVO4:Eu3+. Under 147nm excitation, (Y0.95-xAlx)VO4nanophosphors showed strong red luminescence due to the 5D0-7F2 transition of Eu3+ at 619nm. The luminescence intensityof YVO4:Eu3+ enhanced with partial substitution of Al3+ for Y3+ and the maximum emission intensity was accomplished at theAl3+ content of 10mol%. By the addition of Al3+, decay time of the (Y,Al)VO4:Eu3+ nanophosphor was decreased in comparisonwith that of the YVO4:Eu3+ nanophosphor. Also, the substitution of Al3+ for Y3+ invited the improvement of color coordinatesdue to the increase of R/O ratio in emission intensity. For the formation of transparent layer, the red nanophosphors werefabricated to the paste with ethyl celluloses, anhydrous terpineol, ethanol and deionized water. By screen printing method, atransparent red phosphor layer was formed onto a glass substrate from the paste. The transparent red phosphor layer exhibitedthe red emission at 619nm under 147nm excitation and the transmittance of ~80% at 600nm.

The microstructure and tensile properties of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duocasting were investigated. Only the Al-Mn alloy showed the typical cast microstructure of columnar and equiaxed crystals. The primary dendrites and eutectic structure were clearly observed in the Al-Si alloy. There existed a macro-interface of Al-Mn/Al-Si alloys in the hybrid aluminum alloys. The macro-interface was well bonded, and the growth of primary dendrites in Al-Si alloy occurred from the macro-interface. The Al-Mn/Al-Si hybrid aluminum alloys with a well-bonded macro-interface showed excellent tensile strength and 0.2% proof stress, both of which are comparable to those values for binary Al-Mn alloy, indicating that the strength is preferentially dominated by the deformation of the Al-Mn alloy side. However, the degree of elongation was between that of binary Al-Mn and Al-Si alloys. The Al-Mn/Al-Si hybrid aluminum alloys were fractured on the Al-Mn alloy side. This was considered to have resulted from the limited deformation in the Al-Mn alloy side, which led to relatively low elongation compared to the binary Al-Mn alloy.

AC and ZnS modified TiO2 composites (AC/ZnS/TiO2) were prepared using a sol-gel method. The composite obtained was characterized by Brunauer-Emmett-Teller (BET) surface area measurements, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, scanning electron microscope (SEM) analysis, and according to the UV-vis absorption spectra (UV-vis). XRD patterns of the composites showed that the AC/ZnS/TiO2 composites contain a typical single and clear anatase phase. The surface properties as observed by SEM present the characterization of the texture of the AC/ZnS/TiO2 composites, showing a homogenous composition in the particles showing the micro-surface structures and morphology of the composites. The EDX spectra of the elemental identification showed the presence of C and Ti with Zn and S peaks for the AC/ZnS/TiO2 composite. UV-vis patterns of the composites showed that these composites had greater photocatalytic activity under visible light irradiation. A rhodamine B (Rh.B) solution under visible light irradiation was used to determine the photocatalytic activity. The degradation of Rh.B was determined using UV/Vis spectrophotometry. An increase in the photocatalytic activity was observed. From the photocatalytic results, the excellent activity of the Y-fullerene/TiO2 composites for the degradation of methylene blue under visible irradiation could be attributed to an increase in the photo-absorption effect caused by the ZnS and to the cooperative effect of the AC.

Insoluble catalytic electrodes were fabricated by RF magnetron sputtering of Pt on Ti substrates and the performance of seawater electrolysis was compared in these electrodes to that is DSA electrodes. The Pt-sputtered insoluble catalytic electrodes were nearly 150 nm-thick with a roughness of 0.18μm, which is 1/660 and 1/12 of these values for the DSA (dimensionally stable anodes) electrodes. The seawater electrolysis performance levels were determined through measurements of the NaOCl concentration, which was the main reaction product after electrolysis using artificial seawater. The NaOCl concentration after 2 h of electrolysis with artificial seawater, which has 3.5% NaCl normally, at current densities of 50, 80 and 140 mA/cm2 were 0.76%, 1.06%, and 2.03%, respectively. A higher current density applied through the electrodes led to higher electrolysis efficiency. The efficiency reached nearly 58% in the Pt-sputtered samples after 2 h of electrolysis. The reaction efficiency of DSA showed higher values than that of the Pt-sputtered insoluble catalytic electrodes. One plausible reason for this is the higher specific surface area of the DSA electrodes; the surface cracks of the DSAs resulted in a higher specific surface area and higher reaction sites. Upon the electrolysis process, some Mg- and Ca-hydroxides, which were minor components in the artificial seawater, were deposited onto the surface of the electrodes, resulting in an increase in the electrical resistances of the electrodes. However, the extent of the increase ranged from 4% to 7% within an electrolysis time of 720 h.

The effect of the alloy systems Al-Mg alloy and Al-Si alloy in this study on the characteristics of die-casting were investigated using solidification simulation software (MAGMAsoft). Generally, it is well known that the casting characteristics of Al-Mg based alloys, such as the fluidity, feedability and die soldering behaviors, are inferior to those of Al-Si based alloys. However, the simulation results of this study showed that the filling pattern behaviors of both the Al-Mg and Al-Si alloys were found to be very similar, whereas the Al-Mg alloy had higher residual stress and greater distortion as generated due to solidification with a larger amount of volumetric shrinkage compared to the Al-Si alloy. The Al-Mg alloy exhibited very high relative numbers of stress-concentrated regions, especially near the rib areas. Owing to the residual stress and distortion, defects were evident in the Al-Mg alloy in the areas predicted by the simulation. However, there were no visible defects observed in the Al-Si alloy. This suggests that an adequate die temperature and casting process optimization are necessary to control and minimize defects when die casting the Al-Mg alloy. A Tatur test was conducted to observe the shrinkage characteristics of the aluminum alloys. The result showed that hot tearing or hot cracking occurred during the solidification of the Al-Mg alloy due to the large amount of shrinkage.

Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently, many studies have focused on controlling the size and morphology of Y2O3 in order to obtain better material performance. Y2O3 powders were prepared under a modified solvothermal condition involving precipitation from metal nitrates with aqueous ammonium hydroxide. The powders were obtained at temperatures at 250˚C after a 6h process. The properties of the Y2O3 powders were studied as a function of the solvent ratio. The synthesis of Y2O3 crystalline particles is possible under a modified solvothermal condition in a water/ethylene glycol solution. Solvothermal processing condition parameters including the pH, reaction temperature and solvent ratio, have significant effects on the formation, phase component, morphology and particle size of yttria powders. Ethylene glycol is a versatile, widely used, inexpensive, and safe capping organic molecule for uniform nanoparticles besides as a solvent. The characterization of the synthesized Y2O3 powders were studied by XRD, SEM (FE-SEM) and TG/DSC. An X-ray diffraction analysis of the synthesized powders indicated the formation of the Y2O3 cubic structure upon calcination. The average crystalline sizes and distribution of the synthesized Y2O3 powders was less than 2 um and broad, respectively. The synthesized particles were spherical and hexagonal in shape. The morphology of the synthesized powders changed with the water and ethylene glycol ratio. The average size and shape of the synthesized particles could be controlled by adjusting the solvent ratio.

When a new bonding agent using coal ash is utilized as a substitute for cement, it has the advantages of offering a reduction in the generation of carbon dioxide and securing the initial mechanical strength such that the agent has attracted strong interest from recycling and eco-friendly construction industries. This study aims to establish the production conditions of new hardening materials using clean bottom ash and an alkali activation process to evaluate the characteristics of newly manufactured hardening materials. The alkali activator for the compression process uses a NaOH solution. This study concentrated on strength development according to the concentration of the NaOH solution, the curing temperature, and the curing time. The highest compressive strength of a compressed body appeared at 61.24MPa after curing at 60˚C for 28 days. This result indicates that a higher curing temperature is required to obtain a higher strength body. Also, the degree of geopolymerization was examined using a scanning electron microscope, revealing a micro-structure consisting of a glass-like matrix and crystalized grains. The microstructures generated from the activation reaction of sodium hydroxide were widely distributed in terms of the factors that exercise an effect on the compressive strength of the geopolymer hardening bodies. The Si/Al ratio of the geopolymer having the maximum strength was about 2.41.

Ti-Ni alloys are widely used in numerous biomedical applications (e.g., orthodontics, cardiovascular science, orthopaedics) due to their distinctive thermomechanical and mechanical properties, such as the shape memory effect, superelasticity and low elastic modulus. In order to increase the biocompatibility of Ti-Ni alloys, many surface modification techniques, such as the sol-gel technique, plasma immersion ion implantation (PIII), laser surface melting, plasma spraying, and chemical vapor deposition, have been employed. In this study, a Ti-49.5Ni (at%) alloy was electrochemically etched in 1M H2SO4+ X (1.5, 2.0, 2.5) wt% HF electrolytes to modify the surface morphology. The morphology, element distribution, crystal structure, roughness and energy of the surface were investigated by scanning electron microscopy (SEM), energy-dispersive Xray spectrometry (EDS), X-ray diffractometry (XRD), atomic force microscopy (AFM) and contact angle analysis. Micro-sized pores were formed on the Ti-49.5Ni (at%) alloy surface by electrochemical etching with 1M H2SO4+ X (1.5, 2.0, 2.5) wt% HF. The volume fractions of the pores were increased by increasing the concentration of the HF electrolytes. Depending on the HF concentration, different pore sizes, heights, surface roughness levels, and surface energy levels were obtained. To investigate the osteoblast adhesion of the electrochemically etched Ti-49.5Ni (at%) alloy, a MTT test was performed. The degree of osteoblast adhesion was increased at a high concentration of HF-treated surface structures.

A Li2O-2SiO2 (LS2) glass was investigated as a lithium-ion conducting oxide glass, which is applicable to a fast ionic conductor even at low temperature due to its high mechanical strength and chemical stability. The Li2O-2SiO2 glass is likely to be broken into small pieces when quenched; thus, it is difficult to fabricate a specifically sized sample. The production of properly sized glass samples is necessary for device applications. In this study, we applied spark plasma sintering (SPS) to fabricate LS2 glass samples which have a particular size as well as high transparency. The sintered samples, 15mmφ×2mmT in size, (LS2-s) were produced by SPS between 480˚C and 500˚C at 45MPa for 3~5mim, after which the thermal and dielectric properties of the LS2-s samples were compared with those of quenched glass (LS2-q) samples. Thermal behavior, crystalline structure, and electrical conductivity of both samples were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and an impedance/gain-phase analyzer, respectively. The results showed that the LS2-s had an amorphous structure, like the LS2-q sample, and that both samples took on the lithium disilicate structure after the heat treatment at 800˚C. We observed similar dielectric peaks in both of the samples between room temperature and 700˚C. The DC activation energies of the LS2-q and LS2-s samples were 0.48±0.05eV and 0.66±0.04eV, while the AC activation energies were 0.48±0.05eV and 0.68±0.04eV, respectively.

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.

The purpose of this study was to identify the factors determining the participation restriction of chronic stroke patients based on international classification of functioning, disability, and health (ICF) model. Sixty-eight stroke patients participated. The participants were assessed participation restriction using the Korean version of London handicap scale (K-LHS), modified Barthel index (K-MBI) to measure activities of daily living, Berg balance scale (K-BBS) to assess balance, and the center for epidemiologic studies depression (K-CES-D) to gauge depression. Also, 3 minutes walking test (3MWT), gait velocity, asymmetric posture, and family support were assessed. A stepwise multiple regression analysis was used to explore the factors determining participation restriction. There were no significant different in the K-LHS and K-MBI results by gender (p>.05). Correlations between the K-LHS and K-MBI (r=-.656), K-BBS (r=-.543), K-CES-D (r=.266), 3MWT (r=-.363), gait velocity (r=.348), and family support (r=-.389) were significant (p<.05). Also, the K-MBI and family support were the factors that determined participation restriction (p<.05) and that 40.2% of the variation in the K-LHS can be explained. Therefore, it is suggested that evaluation and intervention of patient's activity level and extent of family support is necessary to reduce participation restriction of chronic stroke patients.

The purpose of this study was to identify the effects of two types of stretching extensor carpi radialis on the visual analog scale (VAS), pressure-pain thresholds (PPTs), grip strength (GS), and strength of wrist extensor (SWE) in patients with lateral epicondylalgia. Sixteen patients with lateral epicondylalgia were recruited for this study and randomly assigned to two groups; the conventional stretching group (CS) and the stretching of proximal functional massage group (PFM); the VAS, PPTs, GS, and SWE were measured before and after the intervention. Over a period of stretching exercises were performed for five minutes per day, five days per week. The paired t-test and Wilcoxon signed-rank test were used to determine the statistical differences in the VAS, PPTs, GS, and SWE (pre- and post-test). The Independent t-test and Mann-Whitney U test were used to compare the effects of stretching exercises between the CS and PFM groups. The results of this study demonstrated that in the PFM group, the PPTs, GS, and SWE significantly increased, and the VAS decreased (p<.05). In the CS group, the VAS and GS increased significantly after the three-week intervention (p<.05). Pain was decreased and strength (GS and SWE) was increased in the PFM group, compared to the CS group (p<.05). The findings of this study indicate that PFM technique can be applied for decreasing pain and increasing the GS and SWE in patients with lateral epicondylalgia.

This study examines the effects of a rehabilitation program on quality of life (QOL), cardiopulmonary function and fatigue during radiotherapy for breast cancer patients. The program includes aerobic exercise, stretching and strengthening exercises. Sixty-five women participated in this study and they were asked to perform supervised exercises that last for 60 minutes five times a week for six weeks. The European organization for research and treatment of cancer-cancer (EORTC QLQ-C30) and the breast (EORTC QLQ-BR23), predicted maximal volume of oxygen consumption () and fatigue severity scale (FSS) were assessed before and after the rehabilitation program. The 60-minute program consisted of a 10-minute warm-up, 30-minute of aerobic exercises, and 15-minute of strengthening exercises, followed by a five-minute cool-down. Heart rates were monitored throughout the exercise class to ensure that patients were exercising at the target heart rate of 40~75% of the age-adjusted heart rate maximum. There were statistically significant differences in the changes of physical function and cancer related symptoms in the EORTC QLQ-C30 and EORTC QLQ-BR23 (p<.05). There was a statistically significant improvement in the predicted (p<.05), although there were no significant differences in the FSS (p>.05). The results of our study suggest that a supervised rehabilitation program may benefit the physical aspects and QOL of patients receiving radiotherapy for breast cancer.

The purpose of this study was to investigate the effect of the two different types of chairs on trapezius muscle activation during dictation tasks. Seventeen university students, each of whom were within standard deviation of the mean Korean standard body size, voluntarily participated in this study. Surface electromyography was used to collect electrical signals from both the upper and lower trapezius muscles. Amplitude Probability Distribution Function (APDF) was performed to analyze the muscle activity. The findings of this study were 1) The backrest-point height of the auditorium chair and the height, length and width of the connected desk were shorter than what was suggested by the KS. Another difference was that the auditorium chair had a bigger angle of the backrest compared to the classroom chair. 2) Regarding within-subject effect the sole statistically significant difference was found between activation of the upper trapezius muscle. The upper trapezius muscle's %RVC in the APDF 10th-50th-90th percentile was statistically higher for participants sitting in the auditorium chair than for participants sitting in the classroom chair (p<.05). 3) There was an interaction effect between the 'two chair-types' and the 'two muscle-sides' in the APDF 10th-50th percentile (p<.05). 4) There was an interaction effect between the 'two chair-types' and the 'three gaze-direction' in the APDF 90th percentile (p<.05). The findings of this study indicated that maintaining a writing posture for a prolonged period of time in an auditorium chair significantly increased the left upper trapezius muscle activation compared to a classroom chair.

The purpose of this study was to assess the influence of patellar height on quadriceps muscles' electromyography (EMG) activity during a squat exercise in adults with patella baja. For the study, we recruited 15 volunteers who had patella baja on the right side. We measured the EMG activity of the right rectus femoris, vastus medialis oblique, and vastus lateralis muscles during squat exercises under two conditions, specifically with and without an infra-patellar strap. The infra-patellar strap was applied below the tested patella to elevate the patella to a normal height. A paired t-test was used to compare the effects of patella height on EMG activity of the quadriceps muscles. The EMG activity of the rectus femoris (RF), vastus medialis oblique (VMO), and vastus lateralis (VL) muscles were significantly decreased during the squat exercise with the infra-patellar strap compared to the same exercise without the infra-patellar strap (p<.05), while the VMO/VL ratio was not different significantly between two conditions (p>.05). The findings of this study suggest that an infra-patellar strap may benefit people with patellar baja, as changes in patellar height could improve the efficiency of the quadriceps muscles.

This study used an unstable platform to change the support surface type and position of both lower limbs in order to determine changes in weight distribution and muscle including the vastus medialis, tibialis anterior, lateral hamstring, and lateral gastrocnemius of both lower limbs were evaluated during knee joint flexing and extending in a semi-squat movement in 32 hemiplegic patients. The support surface conditions applied to the lower limbs were divided into four categories: condition 1 had a stable platform for both lower limbs; condition 2 had an unstable platform for the non-hemiplegic side and a stable platform for the hemiplegic side; condition 3 had a stable platform for the non-hemiplegic side and an unstable platform for the hemiplegic side; and condition 4 had an unstable platform for both sides. The normalized EMG activity levels of muscles and weight bearing ratio of both sides in the four surface conditions were compared using repeated measures ANOVA. A significant increase was found in the weight support distribution for the hemiplegic side in flexing and extending sessions in condition 2 compared to the other conditions (p<.05). A statistically significant decrease in significant decrease in asymmetrical weight bearing in flexing and extending sessions was observed for condition 2 compared to the other conditions (p<.05). A similar significant decrease was found in differences in muscular activity for both lower limbs in condition 2 (p<.05). The muscular activity of the hemiplegic side, based on the support surface for each muscle showed a significantly greater increase in condition 2 (p<.05). An unstable platform for the non-hemiplegic side and a stable platform for the hemiplegic side therefore increased symmetry in terms of the weight support distribution rate and muscle activity of lower limbs in hemiplegic patients. The problem of postural control due to asymmetry in hemiplegic patients should be further studied with the aim of developing continuous effects of functional training based on the type and position of the support surfaces and functional improvement.

The purpose of this study was to determine the effect of contralateral hip adduction (CHA) on thickness of lumbar stabilizers during hip abduction in side-lying. Twenty healthy subjects without back pain were recruited for this study. The thickness of transverse abdominis (TrA), internal oblique (IO) and quadratus lumborum (QL) were measured by ultrasonography. Pelvic lateral tilting motion was measured using a three-dimensional motion analysis system. Measurements were performed at rest position (RP), preferred hip abduction (PHA) and abduction with contralateral hip adduction (CHA) in side-lying at the end of expiration. During the measurements, subjects were asked to maintain steady trunk alignment without hand support. Thickness of TrA and IO was significantly greater in CHA than in PHA and RP conditions. There was no significant difference in thickness of TrA and IO between PHA and RP conditions. Medio-lateral (M-L) thickness of QL was not significant between PHA and CHA conditions. Anterio-posterior (A-P) thickness of QL in PHA and CHA significantly decreased compared to RP condition. Angle of pelvic lateral tilting was significantly decreased in CHA compared to PHA condition. In conclusion, CHA can be recommended for increasing trunk stability without compensatory pelvic motion during hip abduction exercise in side-lying.

The purpose of this study was to determine the effects of weight shift training with joint mobilization on the ankle joint passive range of motion (PROM), balance capacity and gait velocity in hemiplegic patients. Fourteen subjects were randomly assigned to either the experimental group (EG) or the control group (CG), with seven subjects in each group. The EG received weight shift training with joint mobilization in the paretic leg's subtalar joint in order to increase ankle dorsiflexion. The CG received general physical therapy training. Both groups received training five times a week over a period of two consecutive weeks. The figures for PROM of ankle dorsiflexion on the paretic leg, the functional reach test (FRT), the timed up and go (TUG) test, and gait velocity were recorded both before and after the training sessions for both groups. The EG's results in gait velocity, the FRT and the TUG test improved after training (p<.05). The PROM of ankle dorsiflexion improved both in the EG and the CG (p<.05), the EG demonstrated a significantly higher increase (p<.05) than that of the CG. The results of this study suggest that increased joint mobilization positively affects balance and gait velocity of hemiplegic patients. Further studies with a greater sample size are necessary in order further prove the accuracy of the results of this study.

The purpose of this study was to investigate the kinematic and kinetic changes that may occur in the pelvic and spine regions during cross-legged sitting postures. Experiments were performed on sixteen healthy subjects. Data were collected while the subject sat in 4 different sitting postures for 5 seconds: uncrossed sitting with both feet on the floor (Posture A), sitting while placing his right knee on the left knee (Posture B), sitting by placing right ankle on left knee (Posture C), and sitting by placing right ankle over the left ankle (Posture D). The order of the sitting posture was random. The sagittal plane angles (pelvic tilt, lumbar A-P curve, thoracic A-P curve) and the frontal plane angles (pelvic obliquity, lumber lateral curves, thoracic lateral curves) were obtained using VICON system with 6 cameras and analyzed with Nexus software. The pressure on each buttock was measured using Tekscan. Repeated one-way analysis of variance (ANOVA) was used to compare the angle and pressure across the four postures. The Bonferroni's post hoc test was used to determine the differences between upright trunk sitting and cross-legged postures. In sagittal plane, cross-legged sitting postures showed significantly greater kyphotic curves in lumbar and thoracic spine when compared uncrossed sitting posture. Also, pelvic posterior tilting was greater in cross-legged postures. In frontal plane, only height of the right pelvic was significantly higher in Posture B than in Posture A. Finally, in Posture B, the pressure on the right buttock area was greater than Posture A and, in Posture C, the pressure on the left buttock area was greater than Posture A. However, all dependent variables in both planes did not demonstrate any significant difference among the three cross-legged postures (p>.05). The findings suggest that asymmetric changes in the pelvic and spine region secondary to the prolonged cross-legged sitting postures may cause lower back pain and deformities in the spine structures.

The particle size of MgO was examined as a function of the Na content in Mg(OH)2 powders and the calcination temperature. Mg(OH)2 suspension was obtained by dropwise precipitation of Mg(NO3)2·6H2O and NaOH solutions. The suspension was diluted by varying the dilution volume ratio of distilled water to Mg(OH)2 suspension to change the Na salt concentration in the suspension. Mg(OH)2 slurry was filtered and dried at 60˚C under vacuum, and then its Mg(OH)2 powder was calcined to produce MgO with different amount of Na content at 500~900˚C under air. Investigation of the physical and chemical properties of the various MgO powders with dilution ratio and calcination temperature variation was done by X-ray diffraction, transmission electron microscopy, BET specific surface area and thermal gravimetric analysis. It was observed that MgO particle size could depend on the condition of calcination temperature and dilution ratio of the Mg(OH)2 suspension. The particle size of the MgO depends on the Na content remaining in the Mg(OH)2 powder, which powder was prepared by changing the dilution ratio of the Mg(OH)2 suspension. This change increased as the calcination temperature increased and decreased as the dilution ratio increased. The growth of MgO particle size according to the increase of temperature was more effective when there was a relatively high content of Na. The increase of Na content lowered the temperature at which decomposition of Mg(OH)2 to MgO took place, thereby promoting the crystal growth of MgO.