• Journal of the Korean Society for Precision Engineering
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• v.11 no.3
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• pp.105-121
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• 1994

In this paper, we proposed the two-parameter model for predicting the residual strength in CFRP laminated composites subjected to high velocity impact and developed and formulated it based upon Cparino's by using the ratio of impact and the normalized residual strength. Critical indentation was obtained by the statical indentation tests. Impact tests were carried out through air-gun type impact equipment with the velocities varied 30-100m/sec. Projectiles were steel balls with 5 and 7mm in diameter. Test material was carbon/epoxy. The specimens were composed of [ .+-. 45 .deg. /0 .deg. /90 .deg. ]$\_$2/ and [ .+-. 45 .deg. ]$\_$4/stacking sequences and had 0.75$\^$T/*0.26$\^$W/*100$\^$L/(mm) dimension. Results from the proposed model were in good agreement with the test data. And failure mechanism due to high velocity impact is given here to examine the initation and deveolpment of damage by fractography and ultrasonic image system. The effects of the 0 .deg. -direction ply position and the amount to damage area on the residual strength are considered here.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.13-19
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• 2021

To provide empirical evidence on the impact of export instability on economic growth in developing countries, this study estimated the neoclassical production function using data of the Jordanian economy for the period 1995-2019. Real exports, real capital, and export instability were the independent variables in the production function. To determine the appropriate methodology for estimating the production function, the study conducted some preliminary tests, including the Augmented-Dickey Fuller (ADF), on the study data. The results of this test indicated that all study variables were stationary at first difference. Therefore, the Johanson cointegration test was applied to determine that there was cointegration between the study variables since the results of the former test indicated that there was one cointegration vector between these variables. The cointegration equation revealed a positive and statistically significant impact of real capital, real exports, and an indicator of export instability on economic growth. The most important policy implications for these results would be reducing the geographical concentration of exports through the expansion of free trade agreements (FTA) to enhance the positive impact of the instability of exports on economic growth. Moreover, the study recommends strengthening export-oriented actions to achieve higher levels of economic growth.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.259-266
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• 2000

Crash test data from different impact modes and threshold speeds were used to assess the effects of impact conditions on air bag electronic single point sensing (ESPS) activation requirements. The requirements are expressed in terms of the desired sensor activation time based on unbelted driver dummy kinematics. A crash discriminator pre-displacement is introduced to crash recognition algorithm to the ESPS. The new crash recognition algorithm named Velocity Energy Pre-displacement(VEPD) method is developed and the ESPS algorithm based on the VEPD technique is used to assess the ESPS system performance. It is shown that VEPD method correlates very well with desired sensor activation time and meets the activation requirement.

• Journal of Auto-vehicle Safety Association
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• v.8 no.2
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• pp.11-16
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• 2016

The objective of this study was to construct the spring-mass models for the car-to-car offset frontal impact crash. The SISAME software was utilized to extract the spring-mass models using the data from the offset frontal crash test. The spring-mass model of the passenger car could effectively approximate the crash characteristics for the offset frontal barrier impact and the car-to-car offset frontal impact scenarios.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.411-418
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• 2002

In domestic road construction sites, the compaction control based on strength are widely performed through the direct method with high accuracy, such as Plate Loading Test or Field CBR test. It is impossible to manage all construction sites using the direct method because the direct method requires heavy reaction loads and long measurement time. Therefore, it is necessary to apply the indirect method that could control the relative density of construction sites on the whole. Indirect methods, such as Cone Penetration Test and Fall Cone Test, require extra time for data analyzing and fixed area for test device. In this paper, the field applicability of Soil Impact Hammer (SIH) was investigated comparing with the results of field measurement tests and laboratory compaction tests. SIH developed by Japan Construction Administration and Asanuma Ltd., is a kind of indirect methods for compaction checking. According to the results of SIH performed in domestic road construction site, the subgrade reaction modulus obtained from SIH are similar to that from Plate loading tests in the range of 10 to 40. In comparison with laboratory compaction test, similar compaction line are shown in the dry side of optimum moisture contents.

• Journal of the Korean Society of Safety
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• v.13 no.2
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• pp.30-38
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• 1998

In this study, in order to measure energy-absorbing characteristics in impact test of CFRP thin-walled laminates and interpret the cause of decreasing age when collapse test is carried out under the environments of high temperatures and hygrothermals, the moisture absorbing behavior according to the variety of orientation angle is observed and impact collapse characteristics of no moisture absorbing status is compared with that under the environments of high temperatures and hygrothermals. Especially, we try to obtain quantitative design data to develop CFRP thin-walled laminates with energy characteristics of optimum impact absorbing. The value of the maximum loading, mean loading, rate of energy absorption energy per unit volume and mass in CFRP thin-walled laminates on the high temperatures and hygrothermals is measured much lower than under no moisture absorbing. The maximum collapse loading in dynamic impact test is taken measurements lower than in static collapse test CFRP circular laminates in high temperatures and hygrothermals. But the absorbed energy per unit mass and volume is almost same each other and the biggest amount of energy is shown in CFRP circular laminates with orientation angle of $15^{\circ}$. Therefore, in the case of using CFRP circular laminates with axisymmetric mode, CFRP thin-walled structural members with orientation angle of $10^{\circ}$, $15^{\circ}$ has generally best condition.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.1
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• pp.35-46
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• 2023

A model test is performed to measure the sloshing impact pressure in the liquid tank. A preprocessing is performed to learn the model test results applied with various environmental conditions. In this study, we propose a method for generating data similar to the total pressure data using Generative Adversarial Networks. In addition, after approximating the generated result to the three parameter Weibull distribution, the difference of the three parameters was compared through the RMSE and SMAPE calculation results. As a result, the distribution of the generated data showed similar results to the total pressure data distribution.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.3 s.18
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• pp.11-20
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• 2004

In this paper, the acceptance criteria(Striking Velocities) for the A12519 weldments have been developed. Dynamic impact simulation of A12519 plate was achieved by using LS-DYNA, and predict the projectile velocity and the crack length. Also, Ballistic impact tests of A12519 plate have been performed, and compared with analysis results. Critical velocities of A12519 plate were acquired respectively, and striking velocities of A12519 weldments were calculated. Present work data will be used by basic data in ballistic impact test for A12519 weldments.

• The Journal of Industrial Distribution & Business
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• v.5 no.3
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• pp.15-24
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• 2014

Purpose - This study was conducted to identify the impact of teachers' professional development on students' performance. It examines the nature of association between teachers' professional development and students' performance, and analyzes how students can be affected by different factors of teachers' professional development. Research design, data, and methodology - In order to obtain the required goals, Data were randomly collected from 100 students and 45 teachers from three different institutes that are affiliated with KPK Agriculture University, Peshawar. To test the association between teachers' professional development and students' performance, the Chi-square test was applied. Gamma measurement was computed to check the direction of association. Results - The results of the study supported the statement that there exists a positive relationship between teachers' professional development and students' performance. Conclusion - Based on the findings it is surmised that, in order to create a clear learning relationship between teachers and students, management must support the teachers through peer group discussions and training opportunities, and should choose-teachers who can make students pursue the learning of subject knowledge with practical implementation.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.532-537
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• 2011

This paper describes the development of SPH(Smooth Particle Hydrodynamics) scheme and integration into the multi-material shock physics code(ExLO) for the purpose of the application to the extreme large deformation problems. SPH numerical scheme has been extended into the fluid dynamics and the high-speed impact events, such as space structure protection against space debris and meteorite catering. Like other hydrocodes, SPH scheme also solves the conservation equations with the constitutive equation including equation of state. The benchmark problem, Taylor-Impact test, was simulated and the predictions show good agreements with both the published numerical data and experimental data. Currently, the contact treatment between materials is under development.