• The Korean Journal of Applied Statistics
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• v.9 no.1
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• pp.53-73
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• 1996

This paper compares two accelerated life for Weibull distribution. One is the optimum constant stress accelerated life test which minimizes the asymptotic variance of maximum likelihood estimator of a specified quantile at design stress, and the other is corresponding simple step stress test. The models and optimum designs of constant stress and step stress tests are reviewed. Behaviors of asymptotic variances, effects of design parameters to optimum tests, and expected numbers of failures and expected test times of the two tests are investigated. The efficiency of step stress test relative to constant stress test is studied in terms of variance ratio, and robustness to preestimates of design parameters are investigated.

• Journal of the Korean Geotechnical Society
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• v.35 no.8
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• pp.17-30
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• 2019

Based on pile load test results for various pile types that were constructed in-situ and pile design data of prebored PHC piles, the ratio of skin friction to total capacity (SRF) was analyzed. A SRF distribution range from the pile load test results for pilot test prebored PHC piles was 42~99% regardless of relative penetration lengths, soil types, and pile load test types. However, a SRF distribution range from the pile design data for prebored PHC piles was 20~53% regardless of relative penetration lengths and pile diameters. Also, a SRF distribution range from the restrike dynamic pile load test results for pretest working prebored PHC piles was a scattered range of 4~83% regardless of pile diameters, relative penetration lengths and soil types. The scattered SRF of pretest working piles was caused to the quality control issue on the filling of cement milk around piles and this quality control issue should be improved. The average SRF calculated by the current design method was estimated to be 2.2 times lower than the average SRF of the pilot test piles. It is because skin friction resistance is calculated at a very low level. Therefore, a new design method for skin friction will be proposed based on this study.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.29-36
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• 2009

In this paper, a case of a high-rise building supported by a large-diameter drilled shaft socketed in a weathered ground has been studied. The design case of pile foundation presented in this paper could be a representative example of execution of pile design through three(3) design stages of "preliminary design-proof test-supplementary design". As proof test, two(2) BDH PLT (Bi-directional High Pressure Pile Load Test) were performed at the early construction stage. By following the design process of this way, the economic pile design could be carried out and a large amount of construction cost saving could be realized.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.34-42
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• 2018

In order to minimize the deformation of asphalt concrete track(ACT) and ensure the structural safety, a wide type concrete sleeper is necessary to distribute vehicle loading and reduce the exposure of the asphalt roadbed. In this research, the wide prestressed concrete(PSC) sleeper for ACT was developed through the shape design and the structural safety was reviewed using finite element analysis. Furthermore, static test, dynamic test and fatigue test were carried out according to EN13230-2 to verify the design appropriateness of the wide PSC sleepers for ACT. The performance test showed that the developed wide PSC sleeper for ACT meets all the performance requirements by European standard.

• International Journal of Railway
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• v.1 no.3
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• pp.122-127
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• 2008

Rubber components are widely used in many application such as vibration isolators, damping, ride quality. Rubber spring is used in primary suspension system for railway vehicle. Characteristics and useful life prediction of rubber spring was very important in design procedure to assure the safety and reliability. Non-linear properties of rubber material which are described as strain energy function are important parameter to design and evaluate of rubber spring. These are determined by physical tests which are uniaxial tension, equi-biaxial tension and pure shear test. The computer simulation was executed to predict and evaluate the load capacity and stiffness for rubber spring. In order to investigate the useful life, the acceleration test were carried out. Acceleration test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful life prediction for rubber spring were proposed.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.113-117
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• 2003

The digital systems include the noise in power supply, ground and packaging due to a simultaneous switching of signal, signal reflections and distortions on single and multiple transmission lines. The requirement for the controlled impedance on a PCB can be both a critical success factor and a design challenge. So, the invented tool simulates the tracks controlled impedance with the test coupon. It can saves the design time and supports the economical PCB design.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.607-618
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• 2002

Crossover design is often used in clinical trials about chronic diseases like hypertension, asthma and arthritis. In this paper, we suggest nonparametric approaches of Friedman-type rank test based on Bernard-van Elteren test and of aligned method keeping the information of blocks based on the AB/BA/AA/BB crossover design. The simulation results are presented to compare experimental error and power of several methods.

• Fire Science and Engineering
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• v.2 no.2
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• pp.17-30
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• 1988

In Our Country, the fire safety design is done by the standard furnace fire test. This is haphazard procedure, as the standard furnace fire endurance of structural elements has little relation to the structural element endurance in an actual Compartment fire. The standard furnace fire test results, though obtained at great cost, do not contribute to the understanding of the behavior of structural elements in an elevated temperature environment and can not be applied rationally in fire safety design. The response of a steel and reinforced concrete structure in fire is a very complex problem. Therefore, in this paper is explained about tendency of study for fire safety design in advanced nations.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.108-113
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• 1996

Concrete mix degign and adjustments are somewhat complicated and time-consuming tasks in which various uncertainties and errors are involved and depend on the quality control test results. In this paper, as a tool to minimize the uncertainties and errors the neural network is applied to the concrete mix design. Input data to train and test the neural network are obtained from the results of design and adjustments following the concrete standard specifications of Korea. The results show that neural networks have a strong potential as a tool for concrete mix design.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.533-541
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• 2003

This paper shows the results of train system engineering technology and exterior and interior design of a prototype test train(HSR 350X) which was developed in R&D project titled 'Development of High Speed Railway Technology'. The prototype test train, which has two power cars, two motorized trailers and three trailers, is now being tested on high speed line.