• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.777-781
• /
• 2001

An Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute in October 1999 and has been being operated for altitude testing of the gas turbine engines of 3,000 Ibf class or less. The AETF has been calibrated using several engines such as J69 engine of Teledyne Co. as a facility checkout engine. Based on the test results, uncertainty analyses on the air flow rate and thrust were performed according to ASME PTC 19.1-1998. As the analyses showed that the level of uncertainty was not satisfactory over the whole operating envelop, several modifications of the facility and testing method were made in order to improve the measurement uncertainty. As a result, the uncertainty of the air flow measurement was improved by 0.1 % over all the test conditions, and the net thrust measurement by upto 3%. The improved measurement uncertainties of air flow and thrust are 0.68-0.73% and 0.4-1.3%, respectively.

• Journal of Drive and Control
• /
• v.20 no.1
• /
• pp.34-40
• /
• 2023

The agricultural tractor ROPS test method according to OECD code 4 is a test to assess whether the driver's safety area can be secured when a tractor overturns, and reliability should be ensured. In this study, a model formula and procedure for calculating measurement uncertainty expressing reliability in the field of agricultural machinery testing were established according to the ISO/IEC Guide 98-3:2008. The characteristics of the ROPS test device were assessed and repeated tests were performed, and the were used as factors to calculate the measurement uncertainty. As a result of repeated tests, the accuracy was higher than 1.9 % in all load directions; thus, they were, applied to calculate the type A standard uncertainty. The final expanded uncertainty was calculated within the range of less than ± 7.76 kN of force and ± 6.96 mm of deformation in all load directions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.11
• /
• pp.1496-1502
• /
• 2002

An Altitude Engine Test Facility(AETF) was built at the Korea Aerospace Research Institute in October 1999 and has been being operated for altitude testing of gas turbine engines of 3,000 Ibf class or less. The AETF has been calibrated using several engines such as J69 of Teledyne Co. as a facility checkout engine. Uncertainty analyses on the air flow rate and thrust were performed using the test results, according to ASME PTC 19.1-1998. Several modifications on the facility and test method were made in order to improve the measurement uncertainty to a satisfactory level over the whole operating envelop. Spatial distributions of pressure and temperature were measured, sensors were substituted by more accurate ones, inlet duct was modified to refine the flow quality, and pressure control logic was revised to remove the cell pressure fluctuation. As a result, the uncertainty of the air flow measurement was improved by 0.1% over all the test conditions, and the net thrust measurement by up to 3%. The improved measurement uncertainties of air flow and thrust are 0.68～O.73% and 0.4～1.3%, respectively.

• Journal of Korean Society for Quality Management
• /
• v.45 no.3
• /
• pp.533-547
• /
• 2017

Purpose: This study proposes the main sources of uncertainty and uncertainty analysis of a measurement system of insensitive munitions tests. Methods: We established the mathematical model for calculating measurement uncertainty of insensitive munitions tests, conducted experiments for calculating uncertainties of dynamic sensitivity and overshoot value, and estimated the distributions of uncertainty factors. Results: The measurement uncertainty calculation methods are presented, which include experimental data processing methods for calculating uncertainties of dynamic sensitivity and overshoot value. Conclusion: The measurement of explosion pressure in insensitive munitions tests is an important issue to the reporting test results and classifying reaction types. The more efforts to ensure the reliability of the insensitive munitions tests results are required.

• Korean Journal of Adult Nursing
• /
• v.29 no.3
• /
• pp.323-331
• /
• 2017

Purpose: The purpose of this study was to examine whether the uncertainty mediates relationship between rehabilitation motivation and social support. Methods: Participants were 123 adults patients diagnosed as stroke in a hospital located in a Metropolitan City. Data were collected by self-administered questionnaires measuring uncertainty, family support and medical team support as social support, rehabilitation motivation. Data were analyzed using t-test, one-way ANOVA, Pearson's correlation, and multiple regression analyses. The significance of mediating effect was analyzed by Sobel test. Results: Family support and uncertainty, respectively, were influential on rehabilitation motivation (${\beta}=.39$, p<.001, ${\beta}=-.18$, p=.011). Uncertainty showed partial mediating effect on relationship between family support and rehabilitation motivation, however, the effect was not significant (Z=1.63, p=.103). Conclusion: Interventions improving family support and decreasing uncertainty may be helpful in enhancing rehabilitation motivation.

• Journal of the Society of Naval Architects of Korea
• /
• v.57 no.5
• /
• pp.262-270
• /
• 2020

An outdoor free-running model test system was designed for assessing ship maneuverability with test uncertainty. The test model was a surface combatant of tumblehome hull geometry. The straight forward tests were conducted first to obtain the relationship between the propeller revolution rate and advance speed. During the outdoor tests, the propeller revolution rate to achieve a certain Froude number condition was higher than that in the indoor free-running model tests. Turning circle and zigzag tests for evaluating ship maneuverability criteria were carried out at the propeller revolution rate determined by the straight forward test results. The random and systematic standard uncertainties of maneuvering criteria were obtained by repeated tests and comparison with the indoor free-running model test results, respectively. The test uncertainty was largely dominated by the systematic standard uncertainty, while the random standard uncertainty was small with good repeatability.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05b
• /
• pp.29-35
• /
• 1996

For the Reactor Coolant System(RCS) flow rate measurement by the secondary calorimetric heat balance method, the coolant temperature of the hot leg is needed. Several Resistance Temperature Detectors(RTD) are installed in the hot leg to measure the temperature, but the average value of RTDs does not correctly represent the energy-averaged(bulk) temperature because of the thermal stratification phenomenon. Therefore some correction is introduced to predict the bulk temperature, but the correction inevitably contains uncertainty because the stratification is not defined well quantitatively yet. Therefore a large uncertainty for the correction has been used for the conservative estimation. But unrealistically large uncertainty causes degradation of the measurement method and yields difficulty to meet the acceptance criterion in start-up flow measurement test. In this paper, an analytical estimation is made on the correction and the related uncertainty using the measured hot leg velocity profile of System 80 reactor flow model test and the measured temperatures of YGN 3&4 and PVNGS 1&2 start-up tests. The results reveal that the magnitude of the correction uncertainty is much smaller than that used in the previous design. Therefore, the confidence on the flow rate measurement method can be improved and the difficulty in start-up flow measurement test can be lessened if the smaller correction uncertainty obtained through this estimation is applied.

• Fire Science and Engineering
• /
• v.26 no.1
• /
• pp.16-22
• /
• 2012

In fire test, accurate heat release rate measurements provide important information to define the fire safety characteristics of products. The calculation of heat release rate depends on the errors of measuring parameters in experimental set-up. In this study, the uncertainty factors of heat release rate in the room corner test facility, which is installed at Korea Railroad Research Institute, were analyzed. Through the fire testings for the KTX interior materials, the uncertainties of heat release rate were calculated. Results showed that uncertainty was high in the initial stage of fire test and gradually decreased with the growth of fire. The oxygen concentration was a major factor contributing to the combined relative standard uncertainty.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.11
• /
• pp.1012-1019
• /
• 2000

A proficiency test is one of programs which Korea Research Institute of Standards and Science(KRISS), as national metrology institute, is putting in operation for the mutual recognition arrangement. The Fluid Flow Group of KRISS evaluated the measurement capability for liquid flowmeter calibrator of the national calibration and test organizations. The uncertainty of national standard system was estimated in accordance with Guide to The Expression of Uncertainty in Measurement (ISO), and the turbine flowmeter, which was used for the round-robin test as a reference flowmeter, was characterized. The round-robin tests with the turbine flowmeter package were carried out in 1995 and 1999. The test results of the organizations and those of KRISS agreed within $\pm0.2$%. It is found thus that the organizations have the traceability of the national standard for liquid flow measurement.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.1
• /
• pp.71-83
• /
• 1994

Recently, an interest in the uncertainty analysis on measurement and prediction has been growing. An uncertainty analysis method is applied to the P.O.W test where error sources, estimated errors, their propagation route and their sensitivities to the uncertainty items are clearly illustrated. The uncertainty range for the results obtained from the HMRI Propeller Open Water test is within ${\pm}1%$ which is assumed to be lower than an usual measurement error range of ${\pm}1%$. It has been noticed that the uncertainty analysis can be used quite usefully for detecting dominant error-sources and hence improving the experimental measurement accuracy.