• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.210-217
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• 2010

The effects of cooling rate and onset time of fatigue test on hot ductility of plain carbon steels containing 0.06$\sim$0.8 wt.% carbon were investigated at various temperatures. The tensile tested specimen after fatigue strain during cooling showed higher hot ductility than the specimen fatigued and tensile-strained after cooling. With a decreasing cooling rate from solutionizing temperature to test temperature, hot ductility was increased in all temperature ranges, typically in the trough region, and the minimum point of ductility moved to a lower temperature. Also, the depth and width of the trough decreased with lowering the cooling rate.

• Journal of Korean Clinical Nursing Research
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• v.24 no.3
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• pp.356-362
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• 2018

Purpose: This study was a retrospective cohort study to evaluate the effect of evidence-based guidelines for catheter dysfunction among hemodialysis patients, Success rate and bleeding complications in catheterization were examined. Methods: We performed a retrospective cohort study, including 94 patients with catheter dysfunction who were receiving hemodialysis at a university hospital; 55 in the control group and 39 in the protocol group. This protocol was composed of the catheter dysfunction assessment, conservative management of catheter dysfunction, drug management of catheter dysfunction, catheter function test and maintenance management. Data were analyzed with a Chi-square test and t-test using SPSS/WIN 23.0 program. Results: The patency rate of the protocol group was significantly higher than that of the control group. The rate of bleeding complications was not statistically significant for either the control group or the protocol group before or after application. Conclusion: The application of the guidelines effectively increased the patency rate of the catheter without bleeding complications. It is hoped that this guideline can be disseminated to nurses nationwide to improve the efficiency of catheter function for hemodialysis patients.

• Journal of Korean Biological Nursing Science
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• v.23 no.4
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• pp.298-307
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• 2021

Purpose: This study aimed to investigate the risk factors for cardiac implantable electronic device (CIED)-related infections within the first post-procedural year after CIED insertion. Methods: This study included 509 adult patients undergoing CIED implantation procedures between January 1, 2011 and December 31, 2015. The data were analyzed by t-test, chi-square test, Fisher's exact test, and logistic regression analysis using SPSS/WIN 23.0. Results: Fifteen infections and 494 non-infections were examined. The CIED-related infection rate was 2.9%; patients with 14 pocket infections and one bacteremia were included in the CIED-related infection. The risk factors of CIED-related infections were the estimated glomerular filtration rate (eGFR) of ≤ 45 mL/min/1.73 m² (Odds ratio [OR]= 4.03, 95% confidence interval [CI],1.15-14.10) and taking a new oral anticoagulant (NOAC) (OR = 4.50, 95% CI 1.09-18.55). Conclusion: These results identified the CIED infection rate and risk factors of CIED-related infection. It is necessary to consider these risk factors before the CIED implantation procedure and to establish the relevant nursing interventions.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2905-2918
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• 2023

The valve assembly used in nuclear power plants is important safety-related equipment. In the new standard, the physical attributes are measured using a valve diagnosis test, which is used in the expansion to other non-tested valves using a quantitative test-basis methodology. With a motor-operated actuator, the state of stem's lubrication is related to physical attributes such as the stem factor and the friction coefficient. This study analyzed the numerical transient of fluid and solid lubrication with a squeeze film effect due to the loading rate on the stem and the stem nut using the experimental data. The differential equation that governs the motion mechanism of the stem and stem nut is established and analyzed. The flow rate, the fluid and the solid contact forces are calculated with the friction coefficient. Finally, we found that a change in the friction coefficient results from a change of the shear force in the solid contact mode during the interchange process between the solid contact mode and the fluid contact mode. The qualitative understanding of the squeeze film effect is expanded quantitatively for forces, thread surface distance, velocity, and acceleration, with consideration of the metal solid contact and fluid contact.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.85-94
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• 2013

PURPOSES: The performance of tack coat, commonly used for layer interface bonding, is affected by application rate and curing time. In this study, bonding strength tests were performed according to the application rate and curing time of asphalt emulsion. Based on finding from this study, optimum application rates and curing times are proposed. METHODS: In order to investigate bonding characteristic of asphalt emulsion, tests were performed on both asphalt concrete pavement and portland concrete pavement. Also, asphalt emulsions were tested at the application rate of 0, 0.2, 0.4, 0.6, and $0.8{\ell}/m^2$ and at the curing time of 0, 0.5, 1, 2, and 24 hours. Pull-off test and shear bonding strength test, which commonly used for bonding strength measurement of asphalt emulsion, were adopted for this study. To assess field performance under different testing condition, asphalt emulsions were applied to in-service pavement. Throughout coefficient of determination analysis between material index properties from asphalt emulsion and mechanical response from bonding strength tests, performance correlativity was analyzed. RESULTS: Test results show that optimum application rate for asphalt overlay on asphalt concrete pavement (AOA) and asphalt overlay on concrete pavement (AOC) was $0.4{\sim}0.5{\ell}/m^2$ and $0.3{\sim}0.5{\ell}/m^2$, respectively. According to the curing time increment, tensile strength and shear strength of AOC were increased to 22~44% and 20~39%, respectively. AOA case also show strength increment in tensile strength (42%) and shear strength (9%). We tested the applicability of tack coat materials at the field sites, and our findings demonstrated that the bonding (for D and E) and rapid curing (for B, C, and D, E) performances were superior than others. Among material index properties, there was a high correlation between penetration ratio and bonding strength test result. CONCLUSIONS : Result show that interlayer bonding strength was affected by asphalt emulsion type, application rate and curing time. AOC required slightly higher application ($0.1{\ell}/m^2$) than AOA. Both AOA and AOC cases show higher strength at longer curing time. Up to 2hours of curing, rapid strength increments were observed, but strength increment ratio was decreased after 2hours of curing. From the observed correlation between penetration ratio and bonding strength, it is expected that penetration ratio can be used as one of important factors affecting bonding strength analysis.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.33-43
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• 2014

Recently, the case to construct the structure on the soft clayey ground has increased and in order to the reduction of the cost of construction and maintenance on the social infrastructure facilities we have been trying to improve the soft clayey ground using the existing methods such as the pre-loading method and the vertical drain method. Like this, when various ground improvement methods are applied on the soft clayey ground, a long-term consolidation settlement will be key issue due to low permeability coefficient of cohesive soil. According to existing research results that relate to the consolidation settlement, the loading periods for existing the standard consolidation test (Oedometer test) to obtain the consolidation parameters are needed for minimum ten days or more. Therefore, in this study, the standard consolidation test (24 hours step-loading) and constant strain rate consolidation test changed by strain rate was performed using the remolded marine clay on Gwangyang bay composed of a soft clayey ground of the south-west coast. From the laboratory test results, the characteristics of compression, strain-effective stress relations by constant strain rate and the variation characteristic of the pore water pressure by different of loading speed and the relation between consolidation parameters and constant strain rate are compared and analyzed.

• Particle and aerosol research
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• v.13 no.1
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• pp.17-23
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• 2017

In this study, the test results obtained from the performance tests for CA (Korea Association of Cleaning Air) certificated air cleaners which had been commercially available in Korea from 2003 to 2015 were analyzed. Among the test parameters such as flow rate, particle collection efficiency, clean air delivery rate (CADR), ozone emission, odor removal efficiency and noise level, noise level and CADR were correlated with flow rates. Collection and odor removal efficiencies were 20% higher than the limit of the CA certification. The ozone emissions from the air cleaners were negligible because all the air cleaners were equipped with only HEPA filters, not electrostatic precipitation method which produces ozone.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.8
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• pp.112-119
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• 2004

This paper develops a computer model of a cabover type large truck for estimating the effects of the mounted method of frame on handling performance. The computer model considers two mounted methods of frame; flange mounted and web mounted. Frame is modeled by finite elements using MSC/NASTRAN in order to consider the flexibility of frame. The reliability of the developed computer model is verified by comparing the actual vehicle test results with the simulation results. The actual vehicle test is performed in a double lane change course, and lateral acceleration, yaw rate, and roll angle are measured. To estimate the effects of the mounted method of frame on handling performance, simulations are performed with the flange mounted and web mounted frame. Simulation results show that the web mounted frame＇s variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounted frame＇s variations, especially in the high test velocity and the second part of the double lane course. Also, simulation results show that the web mounted frame＇s tendencies of roll angle, lateral acceleration, and yaw rate advance the flange mounted frame＇s tendencies, especially in the high test velocity and the second part of the double lane course.

• Korean Parent-Child Health Journal
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• v.12 no.2
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• pp.119-130
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• 2009

Purpose: This study was designed to examine the effects of Therapeutic Play Program on the pre-operative anxiety of the preschoolers. The design of this study is a quasi experimental study of non-equivalent control group pre-test/post-test design. Method: The subjects of this study were the hospitalized preschoolers receiving an operation in C University Hospital. These totalled 60 and were divided into a 30-person-control-group and a 30-person-experimental-group. The data was collected from June 1 to October 5, 2002. The Experimental treatment was carried out according to Therapeutic Play Program developed by Researcher. The instruments used in this study were the observational records for Hospitalized preschooler's Anxiety behavior response, pulse rate, and respiration rate of the preschooler's. The collected data were analyzed with real numbers, percentage, t-test, and $X^2$-test, using SPSS WIN 11.0 program. Result: Hypothesis, "The experimental group provided with a Therapeutic Play Program would show a lower score of the pre-operative anxiety behavior(t=13.79, p=.00), pre-operative pulse(t=4.50, p=.00) and pre-operative respiration rate(t=4.29, p=.00) response than when the control group was not provided", was supported. Conclusion: Therapeutic Play Program is determined to be useful for reducing Pre-operative anxiety of the preschoolers.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.147-155
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• 2017

A new endurance test-pattern generation on NAND-flash memory is proposed to improve test cost. We mainly focus on the correlation between the data-pattern and the device error-rate during endurance testing. The novelty is the development of testing method using quasi-random pattern based on device architectures in order to increase the test efficiency during time-consuming endurance testing. It has been proven by the experiments using the commercial 32 nm NAND flash-memory. Using the proposed method, the error-rate increases up to 18.6% compared to that of the conventional method which uses pseudo-random pattern. Endurance testing time using the proposed quasi-random pattern is faster than that of using the conventional pseudo-random pattern since it is possible to reach the target error rate quickly using the proposed one. Accordingly, the proposed method provides more low-cost testing solutions compared to the previous pseudo-random testing patterns.