• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.565-573
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• 2006

Acoustic analysis of a moving sound source required that the measured sound signals be do-Dopplerized and restored as of the original emission signals. The purpose of this research is development of beamforming technique can be applied to the rotor noise source identification. For the do-Dopplerization and reconstruction of emitted sound wave, Forward Propagation Method is applied to the time domain beamforming technique. And validation test were performed using rotating sound source constructed by bended pipe and horn driver. In the validation test using sinusoidal sound wave, sufficient performance of signal processing can be seen, and the effect of measuring duration for accuracy was compared. In the prop-rotor measurements, the acoustic source locations were successfully verified in varying positions for different frequencies and collective pitch angle, in hover condition.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3182-3195
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• 2021

The implementation and validation of multi-dimensional (multi-D) features in thermal-hydraulic system codes aims to extend the application of these codes towards multi-scale simulations. The main goal is the simulation of large-scale three-dimensional effects inside large volumes such as piping or vessel. This novel approach becomes especially relevant during the simulation of accidents with strongly asymmetric flow conditions entailing density gradients. Under such conditions, coolant mixing is a key phenomenon on the eventual variation of the coolant temperature and/or boron concentration at the core inlet and on the extent of a local re-criticality based on the reactivity feedback effects. This approach presents several advantages compared to CFD calculations, mainly concerning the model size and computational efforts. However, the range of applicability and accuracy of the newly implemented physical models at this point is still limited and needs to be further extended. This paper aims at contributing to the validation of the multi-D features of the system code ATHLET based on the simulation of the Tests 1.1 and 2.1, conducted at the test facility ROCOM. Overall, the multi-D features of ATHLET predict reasonably well the evolution from both experiments, despite an observed overprediction of coolant mixing at the vessel during both experiments.

• Korean Journal of Childcare and Education
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• v.18 no.4
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• pp.1-16
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• 2022

Objective: The purpose of this study is to test the psychometric properties of the Maternal Emotion Coaching Questionnaire (MECQ, Lim et al., 2018) in order to measure emotion coaching in mothers of preschoolers. Methods: A total of 316 preschoolers and their mothers participated in this study. Maternal emotion coaching was assessed by self-report and child emotion regulation ability was evaluated by the teacher. Data were analyzed with chi-square tests, reliability analysis, confirmatory factor analysis, latent profile analysis, and F-test. Results: Each item of the MECQ showed proper discriminative power. The MECQ and each subscale demonstrated adequate internal consistency and split-half reliability. Evidence of construct validity was provided by confirmatory factor analysis. The five-factor model including maternal attention, awareness, acceptance, empathy, and guidance showed a good fit. Results of the latent profile analysis revealed three profiles of emotion coaching: excellent, good, and poor. Preschoolers with mothers in the poor coaching profile showed significantly lower emotion regulation ability compared to those in the excellent or good coaching profiles, which suggested discriminative validity of the MECQ. Conclusion/Implications: The MECQ presents a reliable and valid tool to assess emotion coaching in mothers of preschool children and can thus be effectively used for mothers of preschoolers.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.400-406
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• 2010

This paper deals with parameter tuning of the Power System Stabilizer (PSS) for 612 MVA thermal power plants in the KEPCO system and its validation in a field test. In this paper, the selection of parameters, such as lead-lag time constants for phase compensation and system gain, is optimized using linear and eigenvalue analyses. This is then verified through the time-domain transient stability analysis. In the next step, the performance of PSS is finally verified by the generator's on-line field test. After the field test, measured and simulated data are also compared to prove the effectiveness of the models used in the simulations.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.1
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• pp.107-114
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• 2021

High penetration of renewable energy generators causes unnecessary investment for power system facilities. Especially with Korean government policies such as Renewable Energy 3020 and Inter-connection support Responsibility of KEPCO for 1 MW DERs, the applications of DER interconnection in distribution system have been increasing. To save the investment, smart control functions for DERs are required and the test bed for the inverters which have not been prepared are necessary to insure DER inter-connection stability. For this, test bed for advanced functions of a smart inverter has been constructed and the tests for necessary functions have been implemented. In this paper, the test bed and environment as well as specifications are introduced and the test results for the validation of the functions are analyzed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.91-103
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• 2009

A cryptographic module (CM) is an implementation of various cryptographic algorithms and functions by means of hardware or software, When a CM is validated or certified under the CM validation program(CMVP), a finite state model(FSM) of the CM should be developed and provided, However, guides or methods of modeling and analysis of a FSM is not well-known, because the guide is occasionally regarded as a proprietary know-how by developers as well as verifiers of the CM. In this paper, we propose a set of guides on modeling and analysis of a FSM, which is needed for validation of a CM under CMVP, and a transition test path generation algorithm, as well as implement a simple modeling tool (CM-Statecharter). A FSM of a CM is modeled by using the Statechart of UML 2.0, Statechart, overcoming weakness of a FSM, is a formal and easy specification model for finite state modeling of a CM.

• Journal of Broadcast Engineering
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• v.26 no.6
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• pp.790-798
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• 2021

In this paper, we propose a method to improve the accuracy of positioning by adding angle and distance validation to the existing Bluetooth-based positioning method using the angle of arrival. In the existing positioning method, an error occurs in the positioning value due to a multipath phenomenon induced in a non-visible distance environment. The proposed method derives the maximum and minimum angles of arrival that can be measured in consideration of the moving speed of the positioned device, and then examines whether the measured angle of arrival exceeds the range of the maximum and minimum angles of arrival. The accuracy of positioning is improved by conducting a distance validation check to see if the location of the device to be positioned and the distance to the positioning device exceed the effective distance. A simulation was conducted to analyze the positioning performance between the proposed method and the existing method, and it was confirmed that the positioning performance was improved through angle and distance validation compared to the existing method in a situation where the positioning error increased through the simulation results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.933-940
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• 2016

A comparative study between a wind tunnel test and an XFOIL simulation looking at the aerodynamic performance of the airfoil for MW-class wind turbine was conducted for validation in the design stage. Tests are carried out for 21% and 30% thickness-ratio airfoils developed for 5 ~ 10 MW offshore wind turbine and the results are compared with the output from the XFOIL simulation at Reynolds number $1.0{\times}10^7$. The test is performed at a free-stream velocity of 50 m/s, corresponding to a Reynolds number of $2.2{\times}10^6$ based on the chord. Surface roughness is simulated using a zig-zag tape. Discrepancies between the results of the test and the XFOIL analysis are found, however, meaningful data for surface pressure distribution, basic performance and surface roughness effect are obtained from the tests, while useful lift-to-drag ratio data is found by the XFOIL simulation.

• 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 Mechanical Science and Technology
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• v.20 no.10
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• pp.1638-1645
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• 2006

This paper proposes a modeling technique which is able to not only reliably and easily represent the hysteretic characteristics but also analyze the dynamic stress of a taper leaf spring. The flexible multi-body dynamic model of the taper leaf spring is developed by interfacing the finite element model and computation model of the taper leaf spring. Rigid dummy parts are attached at the places where a finite element leaf model is in contact with an adjacent one in order to apply contact model. Friction is defined in the contact model to represent the hysteretic phenomenon of the taper leaf spring. The test of the taper leaf spring is conducted for the validation of the reliability of the flexible multi-body dynamic model of the taper leaf spring developed in this paper. The test is started at an unloaded state with the excitation amplitude of $1{\sim}2mm/sec$ and frequency of 132 mm. First, the simulation is conducted with the same condition as the test. Then, the simulations are conducted with various amplitudes in a loaded state. The hysteretic diagram from the test is compared with the ones from the simulation for the validation of the reliability of the model. The dynamic stress analysis of the taper leaf spring is also conducted with the developed flexible multi-body dynamic model under a dynamic loading condition.