• Journal of Applied Reliability
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• v.11 no.1
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• pp.17-30
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• 2011

Many domestic manufacturers make reflectors for Lamps of BLU(back light units). However, color change and parting occur as a result of diverse usage environment. Therefore, many of the manufacturers are reluctant in R&D investment of reflectors for Lamps of BLU. Hence, in this article reliability assessment criteria for reflector for lamp of BLU are established in terms of performance test, environment test and life test.

• Journal of Applied Reliability
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• v.11 no.1
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• pp.1-15
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• 2011

Automobile markets are so fierce in the world market that every major manufacturer assure the buyer of the car by give a provocative warranty plan for their cars. For instance Hyundai motor company offer 10 years and 100,000 miles of warranty whichever comes first. But in order for this effort to be successful every critical component such as window switch has to be proven to be reliable in an adverse environment. Therefore, in this article reliability assessment criteria for window switch are established in terms of basic performance test, environment test and life test.

• Journal of Korean Society for Quality Management
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• v.46 no.3
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• pp.425-440
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• 2018

Purpose: This study is aimed at developing of the flex resistance testing process at low temperature with the waterproof fabric to suit the military environment, and is designed to fit for the purpose of the waterproof materials in order to optimize the test method by finding out matters to improve from existing the test method and through previous studies. Methods: The test method, which has been applied to flex resistance of existing water-repellent materials, was improved and consequently, differentiated test results could be obtained according to the test temperature, sample size, and flexing method. Results: The testing of the total of 8 samples revealed that performance of the military requirement could hardly be met just by presenting the materials or 2~3 layers when the quality criteria for high functional water repellent fabrics were applied. PTFE(Polytetrafluoroethylene) is preferred to PU(Polyurethane) to be used in the extremely low-temperature environment, but durability under the low-temperature environment may be varied depending on film thickness or laminating technique even if the materials of waterproof films are identical. Therefore, in addition to the material or texture, the test method capable of reflecting durability under the low-temperature environment shall be suggested, and the newly designed test method proposed in this study was shown to suggest differentiated quality criteria by the material. Conclusion: The water resistance measurement and the test method following flex resistance with expanded range of flex will enable the differentiable test of the samples according to the number of repetition. This study is meaningful in that it suggests a differentiable test method capable of establishing a basis of deciding suitable material when selecting military goods made of water repellent material by properly improving the test method.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.781-787
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• 2016

We introduce FEST (Flight Environment Simulation Test) procedures for precise guided missiles to reliably improve systems. Flight vibration specification was established based on power spectral density curves calculated from flight test data of a high speed precise guided missile. A FEST pre-profile was developed according to flight vibration specification and delivered to a precise guided missile assembly. Vibration responses were measured by installing accelerometers on electronic components vulnerable to dynamic forces. The FEST profile was adjusted by comparing the vibration responses and the flight vibration specification. Subsequently, the FEST profile was repeatedly modified through trial and error, because the responses were similar to the flight environment. The modified FEST profile enabled performance testing of assembled precise guided missiles under simulated flight conditions on the ground, where unexpected errors could be corrected before the flight tests, leading to cost and risk reduction in the development of the precise guided missile system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.827-829
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• 2011

Vacuum facility is required for high altitude space environment test to develop satellites or space launch vehicles. We, at Chungnam, National University, developed turbo molecular pump vacuum test facility up to $1.0{\times}10-6$ torr to simulate 200 km altitude environment. In this paper, we present some preliminary vacuum performance test results.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.290-291
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• 2017

This study deals with an evaluation method for testing the robustness of the 4 kW commercial power electronic cooling system to the thermal environment. The power electronic cooling system consists of a cascaded push-pull DC / DC converter, a three-phase DC / AC inverter, and an electric compressor. The system manufactured by the thermal environment evaluation test (heat distribution test, thermal impact test, high temperature operation test, temperature cycle test, low temperature operation test) for the commercial electric power cooling system for commercial vehicle proves that it is robust against thermal environment.

• Journal of Korean Elementary Science Education
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• v.21 no.2
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• pp.143-157
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• 2002

The aims of this study are to develop web-based learning materials for science and environmental education of elementary school. The effect of environmental education was divided into eight to measure: the awareness of using web as environmental material, the ability to use web as environmental material. the awareness of environmental problems, the satisfaction for environmental education using web, the awareness of preserving local environment, self-leading ability to learn environment, the effect of using environment homepage, and the internalization of environmental awareness. This study obtained the following results; First, as a result of post-test, the average of the test group of web-based learning was 1.29 points higher than the control group having traditional learning in the awareness of using web as environmental material, showing a statistically significant difference. Second, as a result of post-test, the average of the test group of web-based learning was 2.80 points higher than the control group in the ability to use web as environmental material, showing a statistically significant difference. Third, as a result of post-test, the average of the test group of web-based learning was 1.10 points higher than the control group in the awareness of environmental problems, showing a statistically significant difference. Fourth, as a result of post-test, the average of the test group of web-based teaming was 0.89 points higher than the control group in the satisfaction for environmental education using web, showing a statistically significant difference. Fifth, as a result of post-test, the average of the test group of web-based learning was 1.70 points higher than the control group in the self-leading ability to learn environment, showing a statistically significant difference. Sixth, as a result of post-test, the average of the test group of web-based learning was 1.21 points higher than the control group in the effect of using environment homepage, showing a statistically significant difference. Finally, as a result of post-test, the average of the test group of web-based learning was 1.39 points higher than the control group in the internalization of environmental awareness, showing a statistically significant difference. Based on these results, it is assumed that the teaching method which applied web-based teaming to science and environmental education in elementary school is a effective strategy for elementary science and on environmental education.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.45-51
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• 2007

The various levels of test are performed to verify the correctness, completeness, and quality of the developed flight software. The three main test levels are unit test, integration test and verification test. The flight software unit test is performed on the individual PC environment using target simulator. And integration and verification test is mainly performed on STB(S/W Test Bed) which provides test and debugging environments for flight software on the target board This document is to present the test environment for the next generation low earth orbit satellite flight software development.

• Nuclear Engineering and Technology
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• v.31 no.1
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• pp.49-57
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• 1999

It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.70-78
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• 2021

Naval surface ships and submarines could be exposed to non-contact underwater explosion(UNDEX) environment. Equipment installed on the ships and submarines could be damaged by shock load generated by UNDEX environment. Therefore, shock survivability of equipment generally evaluated by shock tests. Ground based shock test machine such as Light weight shock test machine(LVSM) is developed to simulate shock load caused by UNDEX environment. In this study, linear dynamic model of LVSM is proposed and evaluated to improve shock test design procedure. Parameters of the model are decided by optimizing time domain response compared to zero payload experiment. Proposed model is verified by comparing simulation results and test results of maximum payload experiment. Finally, shock test design using the model is described for various test equipment weight.