• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.3A
• /
• pp.383-390
• /
• 2008

A Precast Prefabricated Bridge Column using steel tube and prestressing bar was proposed for the application of precast method on substructure. A column specimen designed by the proposed bridge column system was made and performed a quasi-static test. The failure mode appeared to be a flexural failure and there is no damage on column segment connection. And it is good use of the self-centering ability by prestressing force. Test results showed that a column specimen satisfy the earthquake specification, and the structural stability was verified. Nonlinear finite element analysis was performed and compared with the test results. Force-displacement relation and location of crack from the analysis results were compared with the test results and it agreed well. The quantitative analysis was also performed by a parametric study using this modeling technique.

• Tribology and Lubricants
• /
• v.40 no.3
• /
• pp.103-110
• /
• 2024

Gas foil thrust bearings (GFTBs) are oil-free self-acting hydrodynamic bearings that support axial loads with a low friction during airborne operation. They need solid lubricants to reduce dry-friction between the runner and top foil and minimize local wears on their surfaces during start-up and shutdown processes. In this study, we evaluate the lift-off speeds and load capacity performance of a GFTB with Polytetrafluoroethylene (PTFE) surface coating by measuring drag torques during a series of experimental tests at increasing ambient temperatures of 25, 75 and 110℃. An electric heat gun provides hot air to the test GFTB operating in the closed booth to increase the ambient temperature. Test results show that the increasing ambient temperature delays the lift-off speed and decreases the load capacity of the test GFTB. An early developed prediction tool well predicts the measured drag torques at 60 krpm. After all tests, post inspections of the surface coating of the top foil are conducted. Scanning electron microscope (SEM) images imply that abrasive wear and oxidation wear are dominant during the tests at 25℃ and 110℃, respectively. A quantitative energy dispersive spectroscopy (EDS) microanalysis reveals that the weight percentages of carbon, oxygen, and nitrogen decrease, while that of fluorine increases significantly during the highest-temperature tests. The study demonstrates that the increasing ambient temperature noticeably deteriorates the static performances and degrades the surface coating of the test GFTB.

• Journal of Positioning, Navigation, and Timing
• /
• v.13 no.3
• /
• pp.257-268
• /
• 2024

The Korea Augmentation Satellite System (KASS) satellite was successfully launched and service is being started. By receiving messages transmitted from the KASS satellite, users can employ the messages to improve positioning accuracy or to verify the integrity of Global Positioning System (GPS). In this paper, we propose a test method for a beam-formed GPS receiver developed to improve the survivability of KASS augmented messages that can enhance positioning accuracy even in an environment with jamming or interfering signals. Through the test method proposed in this paper, quantitative verification is performed for a beam-formed GPS receiver aimed at maintaining the augmented navigation solution to which KASS augmented messages are applied by tracking the KASS signal as much as possible under conditions where the jamming signal strength is gradually increasing. In addition, the proposed test method includes three conditions; first, a static lab test method for repeated verification of functions under the same conditions; second, a static outdoor test method for performance verification in an operating environment of a platform equipped with the beam-formed GPS receiver; and finally, a dynamic lab test method for performance verification of a moving platform equipped with the beam-formed GPS receiver toward a jammer. In this paper, we propose a method for simulating the jamming signal incident direction through the phase delay of an RF cable designed to prevent unintentional jamming signal emission in both lab and outdoor tests, and a method of applying test software for injecting a jamming signal to compare the survivability performance consistently according to the presence or absence of beamforming signal processing. Through the proposed test method, it was verified that the augmented navigation solution could be output for a longer time period when the beamforming signal processing was applied to the KASS satellite signal in the beam-formed GPS receiver.

• Journal of Food Hygiene and Safety
• /
• v.25 no.3
• /
• pp.238-244
• /
• 2010

Currently, in vitro suspension tests using tubes are used as a authorized test method for sanitizers and disinfectants. However, the methods could not accurately assess the efficacy of sanitizers and disinfectant on the food-contacted surfaces in the field. This study evaluated the effectiveness of 5 kinds of representative sanitizers and disinfectants against E. coli and S. aureus to compare three quantitative surface testing methods that have been internationally standardized. As a result, the ASTM E2111-05 (ASTM(1)) test method obtained 5.18 $\pm$ 0.03 and 5.27 $\pm$ 0.04 log cfu/carrier reduction in dealing with E. coli and S. aureus, respectively, the ASTM E2197-02 (ASTM(2)) test method obtained 4.63 $\pm$ 0.04 and 3.97 $\pm$ 0.03 log cfu/carrier reduction and the CEN EN 13697 test method should 6.14 $\pm$ 0.05 and 5.31 $\pm$ 0.10 log cfu/carrier reduction in clean condition (CEN(1)) but 4.37 $\pm$ 0.02 and 4.06 $\pm$ 0.01 log cfu/carrier reduction in dirty condition (CEN(2)). Among them, CEN(1) showed the highest bactericidal effects, whereas ASTM(2) and CEN(2) revealed low performance (p < 0.05). In conclusion, the bactericidal effects of the ASTM(2) method and the CEN EN 13697 method adopting stainless steel were lower than the ASTM(1) method, which uses glass. The effectiveness assessment results among nationally accredited test methods were different each other. This implies that they could not fit for in the accurate evaluation of sanitization and disinfection on food-contact surfaces in practical food-processing fields. These results could be used as a basic data for establishment of an official surface test methods applicable in the field.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.2
• /
• pp.88-93
• /
• 2011

Purpose: As to analytical method of data, the AutoQUANT software in which it is used quantitative rating of the myocardial perfusion SPECT are reported that there is a difference. Therefore the measured value error of the mutual program is expected to be generated even if the quantitative analysis is made data of the same patient. The purpose of this study is to offer the comparative analysis of myocardial extract method in Quantitative Perfusion SPECT. Materials and methods: We analyzed the 51 patients who were examined by Tc-99m MIBI gated myocardial SPECT in nuclear medicine department of Pusan National University Hospital from June to December 2010(34 men, 17 women, mean age $66.5{\pm}9.9$). We acquired the extracted image in myocardial extract protocol. QPS program that uses the AutoQUANT software measured TID(Transient Ischemic Dilation), ESD(Extent of Stress Defect), SSS(Summed Stress Score). Then analyzed the results. Results: The correlation of appyling myocardial extract is TID(r=0.98), ESD(r=0.99), SSS(r=0.99). In the 95% confidence limit, there was no satistically significant difference(TID p=0.78, ESD p=0.31, SSS p=0.19). After blinding test with a physician for making a qualitative analysis, there was no difference. Conclusion: Quantitative indices in QPS program showed good correlation and the results showed no statistically signigicant difference. The variance between method was small. therefore, the functional parameters by each method can be used interchangeably. Also, we expect patient's satisfaction.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.34 no.3
• /
• pp.75-84
• /
• 1992

The paper manufactories in Sangpyeong Industrial Estates, Chinju, produce more than 80 tons of paper-mill sludge cakes every day, which costs about 840 million won for dump per year. Since the paper-mill sludge is biodegradable, the sludge can he utilized as an organic fertilizer if it is properly decomposed. This may lead to not only dramatic cut of the treatment cost but prevention from secondary environmental contamination due to dump. The primary objective of the study was to explore the quantitative range of major enviromental parameters influencing early composting of paper-mill cakes, naturally pretreated in warn and cold weather. The automatically-controlled reactor was designed, manufactured, and operated for nine days to decompose about 2201 of raw sludge cakes. Four tests(Test 1-Test 4) were implemented for the study of Phase I. Treatments of two levels of initial temperature (40˚C and 28˚C) and two levels of water content + C/N ratio (35% + 40 and 63% + 80) were made to test the significance of their parameters for decomposition of raw sludge cakes pretreated in warm weather. Another four tests (Test 5- Test 8) were implemented for the study of Phase II. Treatments of initial temperature and water content(W/C) + C/N ratio of raw sludge pretreated in cold weather were made to 16˚C and 13% +58 for Test 5, 6˚C and 53% +55 for Test 6, 7˚C and 36% +81 for Test 7, 31˚C and 30% +81 for Test 8. Natural weater condition(pretreatment condition) revealed the importance m composting of the paper-mill sludge cakes. Combination of water content adjustment to about 30% with C/N ratio amendment of about 20 and initial temperature of 30~40˚C was concluded to be the best for early composting of paper-mill sludge cakes with aeration rate and pH fixed. Temperature and C/N ratio were adapted as judging variables for composting degree. In addition, tests for microbial activity were performed to validate the experimental results. Since the temperature and C/N ratio did not coincide in some tests as judging variables for the maturity of the composting sludges, taking one of these parameters could mislead the concept of the maturity (composting conceptually new criterion to provide more reliable information for early composting of paper-mill sludge cakes.

• 한국노년학
• /
• v.30 no.1
• /
• pp.141-157
• /
• 2010

This quasi-experimental study examined the experience of simulation clothes and its effects among undergraduate nursing students. Method: The experimental group consisted of 44 sophomore students in a diploma nursing program, while 41 students comprised the comparison group. Only the experimental group experienced the functional decline of aging after taking on simulation clothes. Homogeneity between the groups was analyzed using t-test, and Fisher's exact test. Paired t-test and t-test were adopted for testing changes of attitudes and awareness of supporting elders. In addition, contents of students' reports of the aging simulation experience were analyzed. Results: No significant quantitative effect was observed in attitudes toward elders and awareness of supporting elders. However, the simulation experience seemed to have enhanced students' understanding of elders and of basic elder care as well. Furthermore, the students could think of preparing for their later lives. Conclusion: The experience of simulation clothes is a meaningful learning opportunity in gerontological nursing curriculum. Students' experiences need to be shared and reinforced in a discussion session. Safety should be secured in the process of the experience. The simulation experience can be further developed to raise its quality.

• Journal of the Korean GEO-environmental Society
• /
• v.23 no.6
• /
• pp.19-23
• /
• 2022

For the substantiation and verification of studies related to the construction of a levee using riverbed soil, real-scale levee construction and experimental studies are essential. One of the most important factors in the experimental study is the reproducibility of the multiple levees with the same initial conditions. Quantitative analysis of the reproducibility should be presented. In this study, a number of physical properties (specific gravity test, sieving test, liquid-plastic limit test, compaction test, on-site Density test) for multiple embankments built with fine-grained bed soil was obtained. The collected data then used to obtain the possibility of reproducing levee through statistical analysis to suggest a process of indicating a numeric initial condition of the real-scale test. As a result of statistical analysis to verify the aforementioned process, it was confirmed that it was possible to quantitatively evaluate the reproducibility of the construction under the same conditions of embankments. This is expected to be a basic data for a full-scale embankment test using riverbed soil including other soil based real-scale tests.

• Aerospace Engineering and Technology
• /
• v.4 no.2
• /
• pp.1-6
• /
• 2005

In this study, the method to improve positioning accuracy under the multi-DGPS coverage is suggested. the linearly interpolated PRC regenerating algorithm was applied to improve the DGPS positioning accuracy at user's position by using the various PRC information obtained from multi-DGPS reference stations. To test the performance of the suggested method, the RTK-GPS result was used as the reference and the quantitative analysis results of the performance of the developed navigation algorithm are presented.

• KIEE International Transactions on Power Engineering
• /
• v.11A no.4
• /
• pp.15-20
• /
• 2001

Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability discusses a methodology to identify crucial transmission lines for stability prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system, and it shows capabilities of the proposed method.