• Advances in Automotive Engineering
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• v.1 no.1
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• pp.123-141
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• 2018

Hardware-in-the-loop (HiL) simulation is a very powerful tool to design, test and verify automotive control systems. However, well-validated and high degree of freedom vehicle models have to be utilized in these simulations in order to obtain realistic results. In this paper, a vehicle dynamics model developed in the Carsim Real Time program environment and its validation has been performed using experimental results. The developed Carsim real time model has been employed in the Tofas R&D hardware-in-the-loop simulator. Experimental and hardware-in-the-loop simulation results have been compared for the standard FMVSS No. 126 test and the results have been found to be in good agreement with each other. Two electronic stability control (ESC) algorithms, named the Basic ESC and the Integrated ESC, taken from the earlier work of the authors have been tested and evaluated in the hardware-in-the-loop simulator. Different evaluation methods have been formulated and used to compare these ESC algorithms. As a result, the Integrated ESC system has been shown superior performance as compared to the Basic ESC algorithm.

• Smart Structures and Systems
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• v.26 no.3
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• pp.373-390
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• 2020

Hybrid simulation (HS) is a versatile tool for structural performance evaluation under dynamic loads. Although real structural responses are often multiple-directional owing to an eccentric mass/stiffness of the structure and/or excitations not along structural major axes, few HS in this field takes into account structural responses in multiple directions. Multi-directional loading is more challenging than uni-directional loading as there is a nonlinear transformation between actuator and specimen coordinate systems, increasing the difficulty of suppressing loading error. Moreover, redundant actuators may exist in multi-directional hybrid simulations of large-scale structures, which requires the loading strategy to contain ineffective loading of multiple actuators. To address these issues, lately a new strategy was conceived for accurate reproduction of desired displacements in bi-directional hybrid simulations (BHS), which is characterized in two features, i.e., iterative displacement command updating based on the Jacobian matrix considering nonlinear geometric relationships, and force-based control for compensating ineffective forces of redundant actuators. This paper performs performance validation and application of this new mixed loading strategy. In particular, virtual BHS considering linear and nonlinear specimen models, and the diversity of actuator properties were carried out. A validation test was implemented with a steel frame specimen. A real application of this strategy to BHS on a full-scale 2-story frame specimen was performed. Studies showed that this strategy exhibited excellent tracking performance for the measured displacements of the control point and remarkable compensation for ineffective forces of the redundant actuator. This strategy was demonstrated to be capable of accurately and effectively reproducing the desired displacements in large-scale BHS.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.50-57
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• 2017

Recently, safety-critical aviation system development programs promoted domestically have been terminated in the middle stage or they have not been put to practical use at the final stage. The program failure may be caused by various factors, but this study focused on imperfect test and evaluation(T&E) procedures. In general, T&E process of a safety-critical system must be distributed throughout the entire life-cycle of the system, have a continuity in phases, and can be implemented in a variety of ways depending on the maturity of the system development and acquisition strategy. This paper aims to present a new strategy by analyzing the domestic and overseas T&E processes to reduce the risk of domestic safety-critical CNS/ATM system development program and increase the success rate of program. First, we discuss the verification and validation techniques for safety-critical systems, analyze the T&E procedures of advanced institutes and the domestic situation, and then compare the domestic and overseas T&E processes to complement the imperfect testing procedure.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2323-2333
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• 2021

The paper proposes a technique for reconstructing the true hardening curve of isotropic materials from ring tensile tests. Neutron irradiated 42XNM alloy tensile properties were investigated. The calculation of the true hardening curve for tensile and compression tests of standard cylindrical samples was performed at the first step. After that, the FEM-model was developed and validated using the ring tension and compression tests (with the hardening curve defined in step 1). Finally, the true hardening curve was calculated by selecting the FEM-model parameters and its validation by ring sample tests in different states using an iterative method. For these samples, experimental and calculated gauge length values were obtained, and the corresponding material's constants were estimated.

• Journal of the Korean Society of Radiology
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• v.17 no.5
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• pp.709-715
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• 2023

In this study, the performance evaluation of image quality for noise reduction was implemented using the U-net deep learning architecture in computed tomography (CT) images. In order to generate input data, the Gaussian noise was applied to ground truth (GT) data, and datasets were consisted of 8:1:1 ratio of train, validation, and test sets among 1300 CT images. The Adagrad, Adam, and AdamW were used as optimizer function, and 10, 50 and 100 times for number of epochs were applied. In addition, learning rates of 0.01, 0.001, and 0.0001 were applied using the U-net deep learning model to compare the output image quality. To analyze the quantitative values, the peak signal to noise ratio (PSNR) and coefficient of variation (COV) were calculated. Based on the results, deep learning model was useful for noise reduction. We suggested that optimized hyper parameters for noise reduction in CT images were AdamW optimizer function, 100 times number of epochs and 0.0001 learning rates.

• Journal of Auto-vehicle Safety Association
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• v.16 no.2
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• pp.60-66
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• 2024

Computer simulation significantly reduces the high costs associated with actual crash tests and is expanding due to its ability to analyze various test results quantitatively that are difficult to measure in real tests. Research on evaluation technologies is limited according to the finite element analysis, which aims to replace structural verification testing. In this study, considerations for virtual crash tests were derived, and the validity of the zero-energy mode (hourglass mode) was analyzed as part of the considerations for validating the results of vehicle crash simulations. The study reflects on the considerations for virtual crash tests and the variation in hourglass coefficient values affects the occurrence of the hourglass mode. As the hourglass coefficient changes, the maximum hourglass energy reaches over 5% of the maximum internal energy, necessitating a conservative review. A comprehensive study of the maximum hourglass energy is required, considering additional analysis results for various models and collision conditions.

• Korean Journal of Environmental Agriculture
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• v.39 no.2
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• pp.130-137
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• 2020

BACKGROUND: Mefentrifluconazole and triticonazole are the triazole fungicides. The maximum residue levels for agricultural products need to be set up. Therefore, development of the official analytical method for determination of mefentrifluconazole and triticonazole residues from agricultural crops was necessary due to safety management, and then a simultaneous analytical method was developed for the determination of mefentrifluconazole and triticonazole in agricultural crops. METHODS AND RESULTS: Samples were extracted using acetonitrile and purified using dispersive solid phase extraction, and then detected with liquid chromatograph-tandem mass spectrometry (LC-MS/MS). Matrix-matched calibration curves (0.0025-0.25 ㎍/mL) were linear into a sample extract with r²>0.99. For validation, the recovery test was carried out at three fortification levels (LOQ, 10 LOQ and 50 LOQ) from agricultural samples. The results for mefentrifluconazole and triticonazole ranged between 92.3 to 115.3% and 91.4 to 108.5%, respectively and RSD (relative standard deviation) values were also below 6.0%. Furthermore, inter-laboratory was conducted to validate the method. CONCLUSION: All values were corresponded with the criteria ranges requested by both the CODEX (CAC/GL 40-1993, 2003) and MFDS guidelines (2016). Therefore, the proposed method can be used as an official analytical method for determination of mefentrifluconazole and triticonazole (triazole fungicides) in the Republic of Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.397-404
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• 2019

When developing a weapon system, a T&E(Test and Evaluation) can be performed using M&S for the test items that cannot be evaluated in the real world. In this case, the VV&A activities are required to prove the credibility of M&S for the T&E. Recently, the use of M&S has been increasing as the R&D trends of weapon systems are becoming more advanced. Therefore, the VV&A activities are also increasing. The VV&A activities aim to verify, validate, and accredit that the simulation can represent a real system and ensure credibility regarding its purpose and intention of use. VV&A activities are divided into V&V and Accreditation. When performing VV&A in the ADD (Agency for Defense Development), the V&V activities are performed by a separate department of the ADD and the accreditation activities are performed in the DTAQ (Defense Agency for Technology and Quality). This paper proposes a V&V process for a T&E of M&S that has been performed in ADD. The process is used to verify and validate the documents and data generated during the development process according to the accreditation criteria, and provides objective data that can be used to judge whether the accreditation decision and acceptance criteria are met.

• Korean Journal of Child Studies
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• v.9 no.2
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• pp.1-28
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• 1988

The purpose of this study was to develop a behavior rating scale for the evaluation of children's development for utilization by preschool teachers. The procedures for the study included content validation, pilot test, and main study. A total of 97 items were retained after the content validation and pilot test. The items of the scale were grouped into five areas (physical, language, cognitive, emotional, and social development) and 11 sub-areas. The resulting "Behavior Rating Scale for Preschool Children" was administered to 479 boys and girls, 3-6 through 6-5 years of age, selected from 10 different kindergartens and early education centers in Seoul, Pusan, and Chonju. The analysis of data was done with SPSS computer programs, including item analysis, Cronbach's ${\alpha}$ for reliability, factor analysis to test construct validity, two-way ANOVA to test age and sex differences, and percentile norms. The 97 items of the scale were found to be satisfactory in terms of item discrimination with indices ranging from .31 to .73. Cronbach's ${\alpha}$ was .98 for the total scale and ranged from .87 to .93 in specific domains, which was considered satisfactory. The factors extracted from each area were consistent with the educational objectives of the Yonsei Open Education Program except for emotional development. The intercorrelations among the domains were relatively high, ranging from .56 to .81. Age differences were significant in cognitive, physical, and language development, but not significant in social and emotional development. Sex differences were significant in all areas with girls higher on the average than the boys. Percentile ranks were drived from the total score for each age group and quartiles were calculated for sub-scores in each domain.

• Journal of Auto-vehicle Safety Association
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• v.9 no.4
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• pp.7-13
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• 2017

As automotive industry develops, the demand for increasing traffic safety is growing. Lots of researches about vehicle convenience and safety technology have been implemented. Now, the autonomous driving test is being conducted all over the world, and the autonomous driving regulations are also being developed. Autonomous vehicles are being commercialized, but autonomous vehicle safety has not been guaranteed yet. This paper presents scenarios that assess the safety of autonomous vehicles by identifying the minimum requirements to ensure safety for a variety of situations on highway. In assessing driving safety, seven scenarios were totally selected. Seven scenarios were related to lane keeping and lane change performance in certain situations. These scenarios were verified by analyzing the driving data acquired through actual vehicle driving. Data analysis was implemented via computer simulation. These scenarios are developed based on existing ADAS evaluation and simulation of autonomous vehicle algorithm. Also Safety evaluation factors are developed based on ISO requirements, other papers and the current traffic regulations.