• Journal of Auto-vehicle Safety Association
• /
• v.15 no.1
• /
• pp.55-62
• /
• 2023

In this study, a chest deflection is predicted by introducing a deep learning technique with the results of the frontal impact of the USNCAP conducted for 110 car models from MY2018 to MY2020. The 120 data are divided into training data and test data, and the training data is divided into training data and validation data to determine the hyperparameters. In this process, the deceleration data of each vehicle is averaged in units of 10 ms from crash pulses measured up to 100 ms. The performance of the deep learning model is measured by the indices of the mean squared error and the mean absolute error on the test data. A DNN (Deep Neural Network) model can give different predictions for the same hyperparameter values at every run. Considering this, the mean and standard deviation of the MSE (Mean Squared Error) and the MAE (Mean Absolute Error) are calculated. In addition, the deep learning model performance according to the inclusion of CVW (Curb Vehicle Weight) is also reviewed.

• Nuclear Engineering and Technology
• /
• v.55 no.12
• /
• pp.4382-4394
• /
• 2023

Passive auto-catalytic recombiners (PARs) are widely used to mitigate a hydrogen hazard. The first step to evaluate the hydrogen safety by PARs is to obtain qualified test data of the PARs for validation of their analytical model. SPARC PAR tests SP8 and SP9 were conducted to evaluate the hydrogen recombination characteristics of a honeycomb-shaped catalyst PAR. To obtain the hydrogen recombination rate from the PAR test data, two methods, Method-1 and Method-2, introduced by the THAI project, were applied. Since a large gradient of hydrogen concentration developed during hydrogen injection can cause a large error in the hydrogen mass obtained by integrating the measured hydrogen concentrations, a gate was installed at the PAR inlet to homogenize hydrogen in the test vessel before the PAR operation in the tests. A computational fluid dynamics (CFD) code with a PAR model was also applied to evaluate the characteristics of the PAR recombination according to the PAR inlet conditions, and the results were compared with those from Method-1 and Method-2. It was confirmed that the recombination rates from Method-1 require a correction factor to be compatible with results from Method-2 and the CFD simulation in the case of the SPARC-PAR tests.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3116-3121
• /
• 2007

In this paper, the inverse shape design is introduced using the permeable wall boundary condition. Inverse shape design defines the blade shape for the prescribed Mach numbers or pressure distribution on its surface. It calculates the normal mass flux from the difference between the calculated and prescribed pressure at the surface. A new geometry can be achieved after applying the quasi one-dimensional continuity equation from the leading edge to the trailing edge. For validation of this method, two test cases are studied. The first test case of inverse shape design illustrates the cosine bump with a strong shock. After seven geometry modifications, the shock-free bump geometry can be obtained. The second example concerns the redesign of a transonic turbine cascade. The initial isentropic Mach distribution has a peak on the upper surface. The target isentropic Mach number distribution was imposed smoothly. The peak of Mach distribution has disappeared at the final geometry. This proposed inverse design method has proven to be an efficient and robust tool in turbomachinery design fields.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2004.04a
• /
• pp.3-8
• /
• 2004

This study describes the validation of the GPS/Levelling using GPS data that were obtained from three Permanent GPS stations of the Jeju island. Each orthometric height of three Permanent GPS stations was calculated from the Bench mark of levelling with Traverse-survey and relative baseline processing The test result shows that the error of closure of orthometric height was about 1.6cm and one of ellipsoidal height was about 1.5cm. This result represents that the geoidal height and undulations are regular in the Jeju island. According to the test results, it is identified that one can calculate the orthometric height using Permanent GPS station data rather than traditional levelling method which has a some complexity especially in Jeju island.

• Korean Journal of Child Studies
• /
• v.29 no.5
• /
• pp.51-63
• /
• 2008

The purpose of this research was to develop an scale to measure mathematics anxiety coping behavior of elementary school children. Of the first 45 items selected from a review of literature, 33 items were selected by content validation, modification and revision. Validity, reliability, and item discrimination was based in responses of 1,831 subjects. Data were analyzed by factor analysis, correlation, Cronbach's, $\alpha$, mean, standard deviation, percentages, and t-test. The resulting Scale of Children's Mathematics Anxiety Coping Behavior consisted of 26 items with 5 factors : active problem-solving, aggressive emotion expression, aversive coping, passive coping, and seeking social support. Cronbach's $\alpha$ ranged from .67 to .86 for five factors. T-test showed the 26 items of the scale to be discriminant.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.11
• /
• pp.3865-3872
• /
• 2011

A quantitative structure-property relationship (QSPR) study was performed for the prediction of the absorption maxima of azobenzene dyes. The entire set of 191 azobenzenes was divided into a training set of 150 azobenzenes and a test set of 41 azobenzenes according to Kennard and Stones algorithm. A seven-descriptor model, with squared correlation coefficient ($R^2$) of 0.8755 and standard error of estimation (s) of 14.476, was developed by applying stepwise multiple linear regression (MLR) analysis on the training set. The reliability of the proposed model was further illustrated using various evaluation techniques: leave-many-out crossvalidation procedure, randomization tests, and validation through the test set.

• Advances in aircraft and spacecraft science
• /
• v.5 no.2
• /
• pp.239-249
• /
• 2018

Physical tests are performed at various stages of the development cycle of a product, from prototype validation to product qualification. Although costly, there are growing demands for qualification tests like endurance vibration testing to be more representative of the real world. At the same time there are growing demands to assess the durability of these items based on FEA simulation. In this paper, we will explain how to set up a CAE-based test and how to correlate the results with some physical measurements. Specific assumptions will be explained and some advantages of using virtual tests will be highlighted such as the reduction of the number of prototypes needed, investigations on failures, evaluation of the level of reliability via sensitivity analysis, evaluation of the margins are at the end of a successful test. This presentation will therefore focus on explaining and showing how virtual tests can enrich the exploitation of physical tests.

• Journal of Families and Better Life
• /
• v.10 no.1 s.19
• /
• pp.1-13
• /
• 1992

The purpose of this study was to validate the Elementary HOME(Home Observation for Measurement of the Environment) with korean elementary children. Subjects were 536 mothers 1st-5th graders in the elementary schools in the Seoul. Pearson's r, pearcentage(%), phi($\phi$/), Cronbach's $\alpha$/ ware conducted for the statistical analysis. The major findings were as follows. 1) The item pass rate(percentage) were ranged 16~98. 2) The discriminant coefficients($\phi$/) of the item were ranged 0.06~0.58. 3) The reliability coefficients of the scale were that the split-falf was 0.84, and Cronbach's $\alpha$/ was 0.88. Considering the length of the scale, these reliability estimates appear to be at an acceptable level 4) The factor analysis and the correlations between HOME and SES indices and children's school schievement to test construct validity were conducted to test construct validity. Eight factors were extracted from the factor analysis and coefficients(r) were ranged 0.16~0.45 and -0.08~0.37.

• Proceedings of the KIEE Conference
• /
• 2007.11b
• /
• pp.78-80
• /
• 2007

The residual flux in transformer's iron cores leads to a distortion of short-circuit current occasionally. And some considerable distortion may have effect on the validation of the test results. To avoid the substantial distortion, a suitable pretest is performed before the actual test. In case of applying this method there must be excessive overvoltage due to switching of an unloaded transformer and chopping of an excitation current. The purpose of this paper is estimate that the effect of the overvoltage results from this phenomenon on insulation performance of short-circuit transformer.

• Journal of KSNVE
• /
• v.11 no.2
• /
• pp.265-275
• /
• 2001

This research has been performed to reveal the hysteresis phenomena of the hunting motion in a railway passenger cars. It is found that there are some factors and its operation region to make the nonlinear critical speed reacts to them more sensitively than the linear critical speed. The simulation results show that a self steering bogie system can be a substitute proposal to improve curving Performance together with the reduction of hysteresis of critical speed. Full scale roller rig test is carried out for the validation of the numerical results. Finally, it is certified that wear of wheel profile and stiffness discontinuities of wheelset suspension caused by deterioration have to be considered in the analysis to predict the hysteresis of critical speed precisely.