• Journal of Applied Reliability
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• v.18 no.2
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• pp.122-129
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• 2018

Purpose: This article develops an optimal reliability acceptance sampling plan for the case where the degradation quantity of the performance characteristic follows Weibull distribution. Method: For developing reliability acceptance sampling plans, the sample size and the acceptance constant are determined based on the accelerated characteristic of the test condition and the product. Results: The sample size and the acceptance constant are provided such that the constraints of the producer and the consumer risks are satisfied. Conclusion: Reliability acceptance sampling plans based on the accelerated degradation test method can be used for the quality control within a resonable amount of cost and time. In this article. an optimal reliability sampling plans are newly developed for this purpose.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1501-1514
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• 2008

Recently, so as to solve the urban transportation problem the LRT(Light Rail Transit) system has been studied on the essential technology and the engineering know-how, which lead lower construction cost and higher reliability. The localization development of rubber tired AGT(Automatic Guided Trainsit) system has performed from 1999 to 2004, as a national project of the Minister of Land, Transport and Maritime Affairs. For the application of the rubber tired AGT system in Busan Subway 3-2 Line, this study is focused on the reliability of aluminium profiles vehicle carbody and the establishment of the test and evaluation technologies. In this paper, 3D modeling simulation was applied to the load test of aluminium vehicle carbody. The reliability of the vehicle carbody was estimated as the fatigue test of welded aluminium profiles. From the test and simulation results, it could be concluded that the developed rubber tired AGT shows a good structural reliability and integrity.

• Journal of Aerospace System Engineering
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• v.9 no.3
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• pp.31-38
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• 2015

Wind Turbines are becoming larger in size in order to improve economic efficiency through cost reduction, such as the construction of growth and power infrastructure of energy efficiency. It have requested the large-scale blade design and production. In the present study the new manufacture technique called a fabric-blade structure using spar, rib, and fabric membrane skin is introduced. The architectural membrane test method has been studied to be applied to the skin of the blade. The density and one-axis tensile tests of the architectural membrane materials are conducted to confirm the physical properties which are necessary to the structural designs and analyses of the wind turbine blade.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.100-105
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• 2003

In this paper, we propose the novel test method effectively to detect short and open faults in CMOS op-amp. The proposed method uses a sinusoidal signal with higher frequency than unit gain bandwidth. Since the proposed test method doesn't need complex algorithm to generate test pattern, the time of test pattern generation is short, and test cost is reduced because a single test pattern is able to detect all target faults. To verify the proposed method, CMOS two-stage operational amplifier with short and open faults is designed and the simulation results of HSPICE for the circuit have shown that the proposed test method can detect short and open faults in CMOS op-amp.

• Journal of Computing Science and Engineering
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• v.2 no.3
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• pp.274-300
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• 2008

Software testing cost can be reduced if the process of testing is automated. However, the test data generation task is still performed mostly by hand although numerous theoretical works have been proposed to automate the process of generating test data and even commercial test data generators appeared on the market. Despite prolific research reports, few attempts have been made to evaluate and characterize those techniques. Therefore, a lot of works have been proposed to automate the process of generating test data. However, there is no overall evaluation and comparison of these techniques. Evaluation and comparison of existing techniques are useful for choosing appropriate approaches for particular applications, and also provide insights into the strengths and weaknesses of current methods. This paper conducts experiments on four representative test data generation techniques and discusses the experimental results. The results of the experiments show that the genetic algorithm (GA)-based test data generation performs the best. However, there are still some weaknesses in the GA-based method. Therefore, we modify the standard GA-based method to cope with these weaknesses. The experiments are carried out to compare the standard GA-based method and two modified versions of the GA-based method.

• Spatial Information Research
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• v.18 no.1
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• pp.1-10
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• 2010

Even after many constructions of test-beds to verify R&D results, there is no standard to set up a consistent and systematic test-bed master plan. Therefore, this research derives standards of a u-city test-bed master plan. To verify these standards, the research constructs the potential U-City master plan targeting Cheongna district in Incheon. Standards of a test-bed master plan which is suggested by this research will bring strengths to construct a test-bed such as clear construction procedures from presenting directions of planning, saving cost, effective management of equipments, and so on.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.450-454
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• 2018

Because of the rapidly changing environment and high uncertainties, the semiconductor industry is in need of appropriate forecasting technology. In particular, both the cost and time in the test process are increasing because the process becomes complicated and there are more factors to consider. In this paper, we propose a prediction model that predicts a final "good" or "bad" on the basis of preconditioning test data generated in the semiconductor test process. The proposed prediction model solves the classification and regression problems that are often dealt with in the semiconductor process and constructs a reliable prediction model. We also implemented a prediction model through various machine learning algorithms. We compared the performance of the prediction models constructed through each algorithm. Actual data of the semiconductor test process was used for accurate prediction model construction and effective test verification.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.1
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• pp.65-71
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• 2011

Steering gear is the part of an automobile that change circular movement of steering wheel to lateral movement of rack to change driving direction. This can be classified with manual and power steering gear. Manual steering gear is operated only with human power while power steering gear use oil pressure support. These days power steering gear is more common to almost of the car. Recently a korean company manufactures a speed sensitive power steering which provide variable steering feel depend on the speed of car. The Broens company of Australia produces and exports the test equipments for the manufacture of power steering valves and assemblies to major vehicle manufactures. Some korean companies imported the test equipments from Australia, thus increasing the cost. The purpose of this study is development of the valve balance test equipment to measure the valve torque of the power steering gear. This study designed and manufactured the valve balance test equipment to take hold of the power steering valve using CAE analysis. In order to evaluate the performance of the developed valve balance test equipment, the R&R tests have been conducted.

• Journal of Auto-vehicle Safety Association
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• v.16 no.3
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• pp.55-63
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• 2024

As autonomous driving performance, such as automatic emergency braking (AEB) and advanced driver assistance systems (ADAS), continues to improve, collision angles and occupant seating postures become more diverse, and there is a need to study how occupant injury mechanisms change depending on the type of collision. Accordingly, a representative crash test mode was derived. Using the derived crash test mode, we analyzed the crash injury mechanism according to the impact angle and the occupant's seating posture (seat back angle). Sled is a crash simulation test that applies a pulse corresponding to the vehicle body acceleration pulse generated during a collision. Sled testing has advantages in terms of cost and time compared to actual vehicle crash testing. We focus on the correlation between crash tests reflecting autonomous vehicle crash modes and Sled tests. The results obtained through this study can be used to develop new crash evaluation methods. As a result, we will present the results of an experimental study on the actual vehicle crash test Sled test method.

• Journal of the Korean Dietetic Association
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• v.9 no.2
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• pp.128-137
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• 2003

The purposes of this study were to investigate the current status of contracted hospital food services and to find out the difference in accordance with the number of beds in hospitals. Thirty six hospitals having more than 100beds in Seoul, Inchon and Kyungkido were the subjects of this study. Data was collected through surveys. The survey was conducted during March and April in 2002. The Questionnaires were mailed to the 36 directors of dietetic departments of the hospitals and 36 managers of contracting patient food services. Statistical analysis was completed using SPSS Win(11.0) for descriptive analysis and t-test. The results of the study are summerized as follows; Ⅰ. Hospital perspective : The range covered by contract food service was 63.3% and 36.7% in hospital food services, and medical nutrition services. The patient and employee food services were in 83.3%, and patient food services were in 6.7%. The methods selecting contractors are general, limited, selected and competitive biddings, and private contracts. The responsibility for supervision of contract food services was the dietetic department (51.7%) in most cases. Hospitals having personnel responsible for contracting affairs were in 75.9% of the cases and 24.1% did not have personnel. The biggest reason for contracting was facilitation of personnel management. The most important criteria on selecting food services contractors was the professionality of the contractor. Ⅱ. Contractor's perspective : The cost per meal in the year 2001 was composed of 1,905 won for food cost, 1,081 won for labor cost, 222 won for expenses, 114 won for VAT, 14 won for rent and 146 won for miscellaneous or controllable expense, representing 109 won loss per meal. The profit-and-loss contract cost is higher than the fee-contract cost. The ratios of food cost, labor cost and expenses are higher and the ratios of miscellaneous or controllable expense, VAT, rent and profit are lower in hospitals with more than 400 beds compared with those less than 400 beds. However, no significant differences are present between these two groups of hospitals. The actual contract period was 2.2 years upon initial contract and 1.2 years upon renewal. The initial investment cost was 53 million won and the cost of renovation and repair was 8.5 million won. Significant differences were present between two groups of hospitals. The conditions of employment and number of personnel hired by contractors for contract patient food services were significantly different according to the number of beds.