• Journal of Korea Foundry Society
• /
• v.33 no.4
• /
• pp.162-170
• /
• 2013

The effects of Mn content and cooling rate on the eutectic reaction of flake graphite cast irons were studied by a combined analysis of macro/micro-structure and cooling curve data. The correlation between the eutectic reaction parameter and macro/microstructure was systematically investigated. Two sets of chemical compositions with different Mn contents were designed to cast. Three types of molds for cylindrical specimens with different diameters were prepared to analyze the cooling rate effect. The difference between undercooling temperature and cementite eutectic temperature (${\Delta}T_1=T_U-T_{E,C}$), which is decreased by increasing the Mn content or increasing the cooling rate, is considered to be a suitable eutectic reaction parameter for predicting graphite morphology. According to the criterion, A-type graphite is mainly suggested to form for ${\Delta}T_1$ over $20^{\circ}C$, and D-type graphite is mainly suggested to form for ${\Delta}T_1$ below $0^{\circ}C$. Eutectic reaction time (${\Delta}T$), which is increased by increasing the Mn content and decreased by increasing the cooling rate, is regarded as a suitable eutectic reaction parameter for predicting eutectic cell size. Eutectic cell size is found to decrease in proportion to the decrease of ${\Delta}T$.

• Korean Chemical Engineering Research
• /
• v.54 no.2
• /
• pp.163-170
• /
• 2016

In order to improve the hydrophilic property of polymer films, coating solutions which showed a good hydrophilic property, were prepared by the sol-gel method. The coating solutions were prepared by adding different types of silane coupling agents (aminosilane, epoxysilane and acrylsilane) to a colloidal silica (15 nm diameter). The solutions prepared by adding aminosilane resulted in gels which could not be used as coating solutions. On the other hand, the coating solutions prepared by the addition of epoxysilane showed contact angles of $10{\sim}15^{\circ}$ and good hydrophilic property at R=0.10~0.15 (R=silane coupling agent/colloidal silica weight ratio). In addition, the coating solutions prepared by the addition of acrylsilane at R=0.03~0.07, exhibited contact angles of $5{\sim}10^{\circ}$, which means better hydrophilic property than aminosilane or epoxysilane.

• Korean Journal of Occupational Health Nursing
• /
• v.28 no.4
• /
• pp.253-261
• /
• 2019

Purpose: This study aimed to identify the influence of job stress, compassion satisfaction, and resilience on depression of nurses. Methods: One hundred seventy six nurses working at one tertiary hospital in one metropolitan city were included. The data collection was conducted from September 1st to October 1st, 2018, using a structured, self-reported questionnaire. The collected data were analyzed using descriptive statistics, t-test, one-way ANOVA, Pearson's correlation coefficients, and multiple regression. Results: The $M{\pm}SD$ age of 170 subjects was $29.62{\pm}5.59$. Depression had significant negative correlations with compassion satisfaction (r=-.50, p<.001) and resilience (r=-.56, p<.001), and a positive correlation with job stress (r=.42, p<.001). In the multiple regression analysis, marital status (${\beta}=-.15$, p=.015), job stress (${\beta}=-.00$, p<.001) and resilience (${\beta}=-5.47$, p<.001) had a significant effect on depression. The explanatory power of the subject's marital status, leisure life, job stress, compassion satisfaction, and resilience on depression was 44.1% (F=27.62, p<.001). Conclusion: The study results showed that single status, low job stress, high resilience may decrease depression of nurses. Reducing job stress and improving resilience of nurses will virtually contribute to reduce their depression that can influence on not only nurses' health status but also their performance and qualitative caring for patients.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.165-170
• /
• 1997

Samples of extruded dispersions of 24 vol.% spherical U-2wt%Mo and U-10wt.%Mo powders in an aluminum matrix were annealed for over 2,000 hours at 40$0^{\circ}C$. No significant dimensional changes occurred in the U-1025.%Mo/aluminum dispersions. The U-2wt.%Mo/aluminum dispersion, however, increased in volume by 26% after 2,000 hours at 40$0^{\circ}C$. This large volume change is mainly due to the formation of voids and cracks resulting from nearly complete interdiffusion of U-Mo and aluminum. Interdiffusion between U-10wt.%Mo and aluminum was found to be minimal. The different diffusion behavior is primarily due to the fact that U-2wt.%Mo decomposes from an as-atomized metastable r-phase(bcc) solid solution into the equilibrium r-U and U$_2$Mo two-phase structure during the experiment, whereas U-10wt.%Mo retains the metastable r-phase structure after the 2,000 hours anneal and thereby displays superior thermal compatibility with aluminum compared to U-2wt.%Mo. In addition, the molybdenium supersaturated in U-10wt.%Mo particles inhibits the diffusion of aluminum atoms along the grain boundary into the particle. Also, the dissolution of only a few Mo atoms in UAL$_3$ retards the formation of the intermediate phase, as Mo atoms need to migrate from new intermetallic compounds to unreacted islands.

• Journal of muscle and joint health
• /
• v.26 no.2
• /
• pp.81-89
• /
• 2019

Purpose: The purpose of this study is to explore factors affecting the retention intention of nurses working at long-term care hospitals. Methods: Data were collected from 147 nurses working in 10 long-term care hospitals using self-report questionnaires of role conflict, job satisfaction, professional pride and retention intention T-test, ANOVA, Pearson correlation and multiple regression were used to analyze the data. Results: The mean age of subjects was $47.4{\pm}10.1$ (22~65). Average length of clinical experiences was $170.12{\pm}98.99$ months. The level of retention intention was significantly different by the educational level (t=4.21, p=.017). Retention Intention was significantly associated with professional job satisfaction (r=.36, p<.001) and professional pride (r=.69, p<.001), but were not significantly correlated with role conflict (r=-.07, p=.376). The multiple regression analysis shows that significant factors, affecting the retention intention were professional pride (t=9.87, p<.001) and job satisfaction (t=3.37, p=.001), which explained 46.1% of the retention intention collectively. Conclusion: It is crucial to make substantial efforts to increase professional pride and job satisfaction in order to increase nurses' retention intention.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.5
• /
• pp.156-170
• /
• 2019

Rapid increasing of smartphones has changed people's lifestyles, and location-based services are providing a platform to provide various conveniences in accordance with these changes. In particular, it may provide convenience to many users if location-based services are provided in an indoor area such as subway station. However, it is still a difficult task to ensure accurate positioning result for guiding routes in subway stations. This study proposes a KAI-R system that allows all processes to be performed in one system for indoor navigation in subway stations. The proposed system includes a new pedestrian step detection method for continuous positioning along with an improved fusion positioning algorithm.

• Journal of radiological science and technology
• /
• v.39 no.2
• /
• pp.163-170
• /
• 2016

To evaluate whether the difference in geometrical characteristics between high-dose-rate (HDR) $^{192}Ir$ sources would influence the dose distributions of intracavitary brachytherapy. Two types of microSelectron HDR $^{192}Ir$ sources (classic and new models) were selected in this study. Two-dimensional (2D) treatment plans for classic and new sources were generated by using PLATO treatment planning system. We compared the point A, point B, and bladder and rectum reference points based on ICRU 38 recommendation. The radial dose function of the new source agrees with that of the classic source except difference of up to 2.6% at the nearest radial distance. The differences of anisotropy functions agree within 2% for r=1, 3, and 5 cm and $20^{\circ}$ < ${\theta}$ < $165^{\circ}$. The largest discrepancies of anisotropy functions reached up to 27% for ${\theta}$ < $20^{\circ}$ at r=0.25 cm and were up to 13%, 10%, and 7% at r=1, 3, and 5 cm for ${\theta}$ > $170^{\circ}$, respectively. There were no significant differences in doses of point A, point B, and bladder point for the treatment plans between the new and classic sources. For the ICRU rectum point, the percent dose difference was on average 0.65% and up to 1.0%. The dose discrepancies between two treatment plans are mainly affected due to the geometrical difference of the source and the sealed capsule.

• Journal of Animal Environmental Science
• /
• v.13 no.3
• /
• pp.161-170
• /
• 2007

Ozone from a pilot-scale ozone generator was treated on fermented pig liquid manure stored in a storage tank in order to reduce odor substances during the process of fermented liquid manure production. The group of ozone treatment showed one less than the organic matter compared that of the control. The preferable condition for characteristic changes was when the ratio of BOD to COD was less than 1.5. Ozone treatment showed better oxidizing power than control as it removed more suspended solids and had less methyl isobutyl ketone(P<0.05). Odor reduction measured by olfactory method was higher in ozone treatment than in control.

• Tuberculosis and Respiratory Diseases
• /
• v.82 no.4
• /
• pp.319-327
• /
• 2019

Background: Radial probe endobronchial ultrasound (R-EBUS), is effective for tissue diagnosis of lung lesions. We evaluated the diagnostic performance of R-EBUS both a guide-sheath and fluoroscopy and identified factors associated with accurate diagnosis. The feasibility of molecular and genetic testing, using specimens obtained by R-EBUS, was also investigated. Methods: The study retrospectively reviewed 211 patients undergoing R-EBUS without a guide-sheath and fluoroscopy, June 2016-May 2017. After excluding 27 patients of which the target lesion was not reached, 184 were finally included. Multivariate logistic regression was used, to identify factors associated with accurate diagnosis. Results: Among 184 patients, R-EBUS-guided biopsy diagnosed malignancy in 109 patients (59%). The remaining 75 patients (41%) with non-malignant results underwent additional work-ups, and 34 were diagnosed with malignancy. Based on final diagnosis, diagnostic accuracy was 80% (136/170), and sensitivity and specificity for malignancy were 76% (109/143) and 100% (27/27), respectively. In multivariate analysis, peripheral location (adjusted odds ratio [aOR], 3.925; 95% confidence interval [CI], 1.203-12.811; p=0.023), and central position of the probe (aOR, 2.435; 95% CI, 1.424-7.013; p=0.035), were associated with accurate diagnosis of malignancy. Molecular and genetic analyses were successful, in all but one case, with inadequate specimens. Conclusion: R-EBUS-guided biopsy without equipment, is effective for tissue diagnosis. Peripheral location and central position of the radial probe, were crucial for accurate diagnosis. Performance of molecular and genetic testing, using samples obtained by R-EBUS, was satisfactory.

• Korean Chemical Engineering Research
• /
• v.50 no.5
• /
• pp.802-807
• /
• 2012

The autothermal reforming of methane to syngas has been carried out in a reactor charged with both a Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO metallic monolith catalyst and an electrically-heated convertor (EHC). The standalone type reactor has a start-up time of less than 2 min with the reactant gas of $700^{\circ}C$ fed to the autothermal reactor. The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. The reactor temperature increased as the reaction shifted from endothermic to exothermic reaction with decreasing $H_2O/CH_4$ ratio. Also the amount of $CO_2$ in the products increases with increasing $H_2O/CH_4$ ratio due to water gas shift reaction. The 97% of $CH_4$ conversion was obtained and the reactor temperature was maintained $600^{\circ}C$ at the condition of $GHSV=10,000\;h^{-1}$ and feed ratio ($H_2O/CH_4=0.6$ and $O_2/CH_4=0.5$). In this condition, the maximum flow rate of the syngas generated from the reactor charged with 170 cc of the metallic monolith catalyst is $0.94\;Nm^3/h$.