• Physical Therapy Korea
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• v.12 no.4
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• pp.48-57
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• 2005

The purpose of this study was to evaluate the general characteristics, complications and level of social adaptation of spinal cord injured patients. The subjects were one hundred forty five members who were inpatients or outpatients from October 1, 2004 to April 30, 2005 in general hospitals and municipal welfare centers for the handicapped located in the metropolitan city of Gwangju. The following results were obtained using Modified Barthel Index (MBI). 1) Gender distribution was 77.9% male and 22.1% female. The mean age at the time of injury was 35.4 and the mean age during the study was 44.2. 2) The degree of paralysis among the subjects was as follows: 49.0% had complete paralysis and 51.0% suffered incomplete paralysis. The most frequently injured lesion among the subjects was cervical (49.0%), followed by thoracic (35.9%), and lumbar (15.2%). 3) The mean MBI score was 63.5. There was statistically significant difference in the MBI score in the relation between complete and incomplete paralysis, the relation between cervical, thoracic, and lumbar injury, and the relation between a recovery period of less than three years and more than three years according to the characteristics of injury (p<.05). 4) There was statistically significant difference in the MBI score of subjects who had complications concerning spasticity, deformity, urinary tract infection, and sexual dysfunction (p<.05). 5) The most serious emotional pain after spinal cord injury resulted from economic issues, which affected 35.2% of the subjects. The group having a shorter recovery period after spinal cord injury complained of psychological matters, the group having a longer recovery period complained about the surrounding environment (lack of convenient facilities), suggesting statistically significant difference (p<.05). 6) The most common activities of the group with injuries more than ten years old included meeting schoolmates and working, while most common activities of the group with injuries less than three years old included attending religious functions and miscellaneous others (watching TV, spending time with family), suggesting statistically significant difference (p<.05).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.58-73
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• 2000

Objectives : This study was performed to evaluate BTEX exposure to gas station service attendants and the critical affect of benzene and MtBE airborne concentration. Methods : the degree of exposure to airborne BTEX and MtBE was examined in the service attendants at seven gas stations across the country during a summer season. The TWAs(time-weighted averages) of atmospheric concentration of substances in personal and area samples, were calculated. The component ratio of BTEX and MtBE in the samples of bulk gasoline from each station studied was also measured. Results : The airborne concentrations of BTEX and MtBE showed a lognormal distribution and The TWA concentrations of benzene in personal samples from each station were 0.089 ppm - 0.18 ppm, and those of toluene were 0.097 ppm - 0.2 ppm. The average TWA concentrations of xylene and ethyl benzene was 0.03 ppm and 0.001 ppm, respectively. The TWA concentrations of MtBE were 0.4 ppm - 1.3 ppm. The volume concentrations of MtBE, toluene, ethyl benzene and xylene in the bulk gasoline samples were 3 - 7.4 %, 3 - 12 %, 0.64 % and 1.5 - 10 %, respectively. Conclusions : The benzene concentration was detected to exceed the ACGIH threshold benzene level of 0.5 ppm, in one of 74 personal and area samples. MtBE, a substitute for aromatic compounds such as benzene in gasoline, was found to bring about a greater chance of exposure to carcinogen, due to its high vapor pressure and carcinogenicity.

• The korean journal of orthodontics
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• v.26 no.6
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• pp.691-703
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• 1996

Three-dimensional finite element model was made from adult skull to find desirable direction of retraction force to treat skeletal class II malocclusion. The retraction force of 400g was applied to the first molar. The direction of the force application was $23^{\circ}$ downward, parallel, $23^{\circ}$ upward and $45^{\circ}$ upward to the occlusal plane. The stress distribution and the displacement within the maxilla were analyzed by three-dimensional finite element method. The findings obtained were as follows: 1. Maxillary first molar was displaced posteriorly and inferiorly in $23^{\circ}$ downward, parallel, $23^{\circ}$ upward retraction but it was displaced posteriorly and superiorly in $45^{\circ}$ upward retraction. 2. ANS, A point and prosthion were moved posteriorly and inferiorly and pterygomaxillary fissure was moved posteriorly and superiorly. Clockwise rotation of maxilla occurred when retraction force was applied. 3. The degree of clockwise rotation of maxilla was greatest when the force was applied $23^{\circ}$ upward to the occlusal plane and was least when the force was applied $23^{\circ}$ downward to the occlusal plane. 4. Large tensile stress appeared in maxillary first molar and alveolar bone and the infraorbital region of maxilla when the force was applied $23^{\circ}$ downward to the occlusal plane. Tensile stress was smaller as the direction of force move upward. 5. Large compressive stress was appeared in maxillary first molar and infraorbital region in $45^{\circ}$ upward case and large compressive stress occurred in the posterior part of maxilla as the retraction force was upward.

• International Commerce and Information Review
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• v.15 no.3
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• pp.135-153
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• 2013

This study aims to investigate the overall relationship between the deterring and facilitating factors in export activities of the small and medium export companies. Nine export deterring factors are analyzed by multinational dimensional scaling(MDS) method to identify key dimensions underlying those factors. Perceptual mapping shows that some factors such as brand image, operating capital and e-trade infra are found similar in its degree of difficulties in export activities. Regression analysis shows that government export promotion measures might play an effective export facilitating factors to ease the export deterring factors like market information and manufacturing skill. Whereas difficulties arising from e-trade infra, operating capital, and brand image might be eliminated by internal competency of company, difficulties from distribution channel might be lessened by overseas orientation of chief executive of company.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.772-778
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• 2012

In this paper, the states and the parameters in the dynamic system are simultaneously estimated by applying the UKF(Unscented Kalman Filter), which is widely used for estimating the state of non-linear systems. Estimating the parameter is very important in various fields, such as system control, modeling, analysis of performance, and prediction. Most of the dynamic systems which are dealt with in engineering have non-linearity as well as some noise. Therefore, the parameter estimation is difficult. This paper estimates the states and the parameters applying to the UKF, which is a non-linear filter and has strong noise. The augmented equation is used by including the addition of the parameter factors to the original state equation of the system. Moreover, it is simulated by applying to a 2-DOF(Degree of Freedom) dynamic system composed of the pendulum and the slide. The measurement noise of the dynamic equation is assumed to be a Gaussian distribution. As the simulation results show, the proposed parameter estimation performs better than the LSM(Least Square Method). Furthermore, the estimation errors and convergence time are within three percent and 0.1 second, respectively. Consequentially, the UKF is able to estimate the system states and the parameters for the system, despite having measurement data with noise.

• Korean Journal of Materials Research
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• v.22 no.2
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• pp.66-70
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• 2012

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 $H_2SO_4$+ 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 $H_2SO_4$+ 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.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.3
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• pp.243-249
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• 2013

Objectives: This study assessed the status of domestic industrial hygiene laboratories using data from on-site investigation for revision of quality control systems in 2012-2013. Methods: The target laboratories were 60 industrial hygiene laboratories chosen by random selection and nationwide distribution which had participated in on-site investigations for revision of quality control systems from March 2012 to August 2013. The investigation was performed on-site following standard quality control procedures. The score between each group was compared using Mann-Whitney and Kruskal-Wallis tests, and the correlation between analytical career, sex, academic major of analyst and score of analytical performance was expressed as Spearman's rank correlation coefficient. Results: The assessment revealed that the items to be improved, in sequence, were effort at staff training (score 65.5), ability to calculate data (score 73.4), establishment of internal quality control guidelines (score 75.7), laboratory facilities (score 77.1), degree of understanding and skill at gas chromatography (score 77.1). Analysis performance showed a positive correlation with career of analyst (r=0.56, p<0.01). Conclusions: The practice of on-site investigation for quality control systems showed the current status of industrial hygiene laboratories in the first trial. There were many laboratories which needed improvement and development of analytical systems. This assessment can provide information for the systematic operation and improvement of facilities at each laboratory. Further practice of this investigation will lead to a proficiency testing and accreditation system for autonomous quality control as is the practice in many countries, rather than mandatory practice by legal regulation.

• Polymer(Korea)
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• v.36 no.6
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• pp.745-755
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• 2012

Two types of polymers were tested in this study; poly(ethylene terephthalate) (PET) as a synthetic example and poly(lactic acid) (PLA) as a natural polymer. DSC analyses showed that the use of nanofiller increased the degree of crystallinity ($X_c$) of both PET and PLA polymers, but the effect was more noticeable on PET nanocomposites. The crystallization of PLA and PET nanocomposites occurred at higher temperatures in comparison to neat polymers. According to dynamic mechanical-thermal analysis (DMTA), the damping factor of PET/$TiO_2$ nanoparticles decreased compared to the neat matrix, but for PLA nanocomposites the opposite trend was observed. Results of the mechanical test showed that for both PET and PLA nanocomposites, the most successful toughening effect was observed at 3 wt% loading of $TiO_2$ nanoparticles. SEM micrographs revealed uniform distribution of $TiO_2$ nanoparticles at 1 and 3 wt% loading levels. The results of WAXD spectra explained that the polymorphs of PLA and PET was not affected by $TiO_2$ nanoparticles. UV-visible spectra showed that $TiO_2$ nanocomposite films had high ultraviolet shielding compared to neat polymer, but there was significant reduction in transparency.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.131-138
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• 2020

In accordance with huge demand for capital to meet the expansion of steel production, there are more and more steel companies who have officially listed their stocks in HOSE and HNX. One of the key issues in successful initial public offerings and seasonal offerings for these companies is how to make stocks of steel companies become more attractive in the eyes of investors. The purpose of this research is to analyze the determinants of share prices of listed steel companies in Vietnam. This study utilized macro-economic variables, ratios and indicators representing characteristics of steel industry collected from Quarter 1/2006 to Quarter 4/2019 in association with the panel data and the feasible generalized least square (FGLS) model to evaluate the degree of these factors on the share prices. The results of the research show that ROE, Cons_rate, and CO2_rate are three main factors affecting the share prices of listed steel companies. Among which, ROE and Cons_rate have a positive effect, while CO2_rate has a negative effect on the share prices of listed steel companies. It also confirms the relationship between the environmental factor, construction industry factor and the stock prices. This lays foundations for recommendations for the future policies towards environmental protection and sustainable development.

• Corrosion Science and Technology
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• v.15 no.3
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• pp.120-124
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• 2016

The effect of alloying element Ca (0, 1, and 2 wt%) on corrosion resistance and bioactivity of the as-received and anodized surface of rolled plate AM60 alloys was investigated. A plasma electrolytic oxidation (PEO) was carried out to form anodic oxide film in $0.5mol\;dm^{-3}\;Na_3PO_4$ solution. The corrosion behavior was studied by polarization measurements while the in vitro bioactivity was tested by soaking the specimens in Simulated Body Fluid (1.5xSBF). Optical micrograph and elemental analysis of the substrate surfaces indicated that the number of intermetallic particles increased with Ca content in the alloys owing to the formation of a new phase $Al_2Ca$. The corrosion resistance of AM60 specimens improved only slightly by alloying with 2 wt% Ca which was attributed to the reticular distribution of $Al_2Ca$ phase existed in the alloy that might became barrier for corrosion propagation across grain boundaries. Corrosion resistance of the three alloys was significantly improved by coating the substrates with anodic oxide film formed by PEO. The film mainly composed of magnesium phosphate with thickness in the range $30-40{\mu}m$. The heat resistant phase of $Al_2Ca$ was believed to retard the plasma discharge during anodization and, hence, decreased the film thickness of Ca-containing alloys. The highest apatite forming ability in 1.5xSBF was observed for AM60-1Ca specimens (both substrate and anodized) that exhibited more degradation than the other two alloys as indicated by surface observation. The increase of surface roughness and the degree of supersaturation of 1.5xSBF due to dissolution of Mg ions from the substrate surface or the release of film compounds from the anodized surface are important factors to enhance deposition of Ca-P compound on the specimen surfaces.