• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.325-330
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• 2009

This study was performed to develop accelerated life test methods for agricultural tractor transmission receiving variable load. To acquire parameters for calculation of accelerated life test, endurance tests were performed under different torque conditions. Test results showed that the shape factor of Weibull distribution was 1.5 and fatigue damage exponent was 5.4. The calculated test time was 5,877 hours under the conditions of average life (MTBF) 3,000 hours and 90% reliability for one test sample. According to the linear cumulative damage rule, test time could be reduced using increased test load. Test time could be reduced by 252 hours when 1.2 times of the rated load compared with 0.67 times of the rated equivalent load calculated by load spectrum of the agricultural tractor. Calculated acceleration coefficient was 23.3.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.45 no.2
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• pp.103-107
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• 2000

The viviparity of 28 rice varieties was tested at 25 days after heading(DAH), 35DAH, and 45DAH in the laboratory and field condition for 12 days. The incubation temperature was 20/l$0^{\circ}C$ (day/night), 25/15$^{\circ}$C$ and 30/20$^{\circ}$C$ in the laboratory test, and under field water conditions in the field test. The biggest varietal difference of viviparity was found in the laboratory test when examined at 45DAH with the 6-day incubation under 25/15$^{\circ}$C$ . At this conditions the mean viviparous ratio was 32.1 % with the range of 53.9 and the variance of 259.5. In the field test, the significant varietal difference in the viviparity was also found in the lodging treatment at 45 DAH for 6 days. Correlation coefficient analysis between the field and laboratory tests was highly significant from 4 days after incubation at 45 DAH and after 6-day incubation at 35 DAH, and correlation coefficient was higher as incubation days in the laboratory and submerged days under field water became longer. Considering the correlation between the field and laboratory tests, varietal difference of viviparity and convenience of testing, the laboratory test at 45 DAH for 6-day incubation under 25/15$^{\circ}$C$ was the most efficient evaluation method for the viviparity of rice cultivar.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.61-66
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• 2012

Conventional method to transform vehicle driving condition to engine operation mode is to use vehicle road load under neutral gear and mechanical efficiency of drivetrain. But this method requires additional measurement of efficiency of drivetrain on a test rig. And this measurement is normally done at fixed speed and thus estimated accuracy of engine operation mode is not considered to be high enough. This study suggests new method to calculate engine operation mode for prescribed driving mode such as NEDC using vehicle coastdown test under gear engaged condition without measurement of mechanical efficiency of drivetrain. Coastdown test was done under neutral and gear engaged condition for comparison and also trial to extract mechanical loss of drivetrain was carried out. Calculated engine torque by conventional and newly suggested method was compared with actually measured torque of a vehicle on a chassis dynamometer during NEDC. Newly suggested method showed slightly higher accuracy of accumulated brake work during NEDC.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.341-344
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• 2009

In this paper, protective function evaluation was conducted to determine the performance and safety of a power conditioning system(PCS) for 1kW residential fuel cell system. It is essential to have a power quality, grid-connection and safety of PCS. Even though it is under 500ms by KGS-A410 standard, it is shown a rapid response time of 25ms from input under-voltage test. In terms of output over/under-voltage test, it is shown 29.15 and 79.4ms. Especially using anti-islanding test, it is shown all times under 100ms for combination cases of real and reactive power. We confirmed a rapid response characteristics and safety of PCS. The results of this evaluation are being used to develop a new test protocols of PCS.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1858-1868
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• 2021

Resisting an accidental impact of large commercial aircrafts is an important aspect of advanced nuclear power plant (NPP) design. Especially after the 9·11 event, some regulations were enacted, which required the design of NPPs should consider the accidental impact of large commercial aircrafts. Normal working of equipment is important for stopping reactor under an impact when an NPP is in operation. However, there is a lack of reliable analysis and research on the impact test of nuclear prototype equipment. Therefore, in order to study the response of the equipment under high acceleration impact, a centrifugal pump is selected as the research object to perform the impact test. A horizontal half-sinusoidal pulse wave was applied to the working pump. The test results show that the horizontal response of the motor and flange is greater compared to other parts, as well as the vertical response of the coupling. The stress response of the pump body support and motor support is high, hence these parts should be considered in the design of the pump. Finally, combined with the damage and stress evaluation results of the pump under different amplitudes, the ultimate impact acceleration that the pump can withstand is given.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.242-245
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• 2006

This paper is an assessment on the dynamic test results of optical bench for LEO satellite. According to the design requirements, optical bench was designed and manufactured. Dynamic test was performed to verify stability of optical bench. Low level random vibration test, sine burst test and sine vibration test are carried out to identify dynamic characteristics and to verify static strength and safety under quasi-static load conditions. From the result it can be stated that the optical bench is well qualified under the launch environmental conditions.

• Journal of Korean Academy of Nursing Administration
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• v.15 no.2
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• pp.275-283
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• 2009

Purpose: This study investigated the effects of reeducation of nursing process on nurses' expertise, critical thinking disposition, and clinical decision making. Methods: Data were collected from March to June, 2007. The subjects were 47 Academic Credit Bank System Student Nurses. They were taught 'nursing process' during 1 semester(15weeks). 47 nurses were divided into three groups according to clinical experience(under 3 years, 3 to under 5 years, 5 years or more). After 15 weeks, the effects of education were compared using a paired t-test between pre-test and post-test. Results: There was a significant difference in the 3 to under 5 years experienced nurses's expertise(t=-3.659, p=.004) between the pre-test and post-test. There was a significant difference in the 5 years or more experienced nurses's expertise(t=-5.781, p<.001) and critical thinking disposition(t=-3.345, p=.003) between the pre-test and post-test. There were no significant differences in clinical decision making(accuracy, proficiency, and confidence) of 3 groups. Conclusion: Reeducation of nursing process is a valuable teaching and an evaluation strategy for 5 years or more experienced nurses to improve expertise and critical thinking disposition. We need to develop continuing education program for improving nurses' clinical decision making.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.263-270
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• 2003

Before the implementation of the 1992 seismic design provisions in Korea, longitudinal steels of RC bridge piers were practically lap-spliced in the plastic hinge region. Experimental investigation was made to evaluate the seismic performance of RC bridge pier specimens in a flexure/shear mode. Six circular test specimens in an aspect ratio of 2.5 (600mm in diameter) were made with test parameters confinement ratio, lap splices, and retrofit FRP materials. They were damaged under a series of artificial earthquakes with 0.22g PGA, being compatible in Korean peninsula, through the pseudo-dynamic test. Probable damages were assessed by the Park and Ang damage index. Approximate 0.1 and 0.3 damage indices were obtained for RC specimens without lap splice and with lap splice, respectively. Directly after the pseudo-dynamic test, damaged test columns were laterally actuated under inelastic reversal cyclic loadings simultaneously under a constant axial load. Through curvature measurements, residual seismic performance was evaluated for test specimens. Test results show that RC pier specimens with lap-spliced appeared to fail at low ductility, but significant improvement was obtained for the ductility of these specimens if externally wrapped with FRP.

• Geomechanics and Engineering
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• v.35 no.1
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• pp.13-27
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• 2023

The model production for large-scale (lateral length ≥ 2.0 m) capillary barrier (CB) model tests is time and cost-intensive. To address these limitations, the framework of a small-scale CB (SSCB) model test under the lateral no-flow condition has been established. In this study, to validate the experimental methodology of the SSCB model test, a series of seepage analyses on the SSCB model test and engineered slopes in the same and additional test conditions was performed. First, the seepage behavior and diversion length (L_D) of the CB system were investigated under three rainfall conditions. In the seepage analysis for the engineered slopes with different slope angles and sand layer thicknesses, the L_D increased with the increase in the slope angle and sand layer thickness, although the increase rate of the L_D with the sand layer thickness exhibited an upper limit. The L_D values from the seepage analysis agreed well with the results estimated from the laboratory SSCB mode test. Therefore, it can be concluded that the experimental methodology of the SSCB model test is one of the promising alternatives to efficiently evaluate the water-shielding performance of the CB system for an engineered slope.

• Journal of Pharmacopuncture
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• v.27 no.1
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• pp.38-46
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• 2024

Objectives: Genotoxicity is evaluated through a chromosomal aberration test using cultured mammalian cells to determine the toxicity of no-pain pharmacopuncture (NPP), which has recently been used to treat musculoskeletal pain disorders in Korean medical clinical practice. Methods: An initial test was performed to determine the dosage range of the NPP, followed by the main test. In this study, NPP doses of 10.0, 5.0, and 2.5%, and negative and positive controls were tested. An in vitro chromosome aberration test was performed using Chinese hamster lung cells under short-term treatment with or without metabolic activation and under continuous treatment without metabolic activation. Results: Compared with the saline negative control group, NPP did not significantly increase the frequency of chromosomal abnormalities in Chinese hamster lung cells, regardless of the presence or absence of metabolic activation. Additionally, the number of cells with structural chromosomal abnormalities was significantly higher in the positive control group than that in the negative control group that received saline. Conclusion: Based on the above results, the chromosomal abnormality-producing effect of NPP was determined to be negative under these test conditions.