• 화약ㆍ발파
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• 제35권1호
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• pp.27-33
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• 2017

본 연구에서는 상용 해석코드인 LS-DYNA 상에서 선택된 금속과 암석을 대상으로 파괴인성시험 과정을 모델링하였다. 이 시험은 각봉의 3점 휨 시험을 토대로 한 것이다. 이 시험을 수행하는 데에는 비교적 긴 시간이 소요되므로 해석과정에서는 Newmark 법을 사용하는 묵시적 해석법을 채택하였다. 본 해석을 통해 얻은 응력확대계수의 값은 금속과 암석의 경우에 각기 $73MPa.m^{0.5}$과 $0.3MPa.m^{0.5}$이었다. 암석 재료모델의 파괴인성 값이 이렇게 작게 나타난 것은 작성된 재료모델이 암석의 특징적인 성질인 취성을 잘 표현하고 있다는 의미이다.

• 항공우주시스템공학회지
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• 제13권3호
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• pp.87-94
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• 2019

본 논문에서는 무인항공기가 수명주기 동안 노출될 수 있는 운용 환경조건 입증을 위한 시험절차를 제안한다. 시험절차는 국방과학연구소 초대형 기후환경 챔버에서 시스템 요구조건을 입증할 수 있도록 수립되었다. 다양한 환경조건 중 비행체 단위에서 요구받는 강우, 습도 및 온도(저온 저장, 저온 운용, 고온 운용 및 일광(고온 저장)) 환경조건에 대하여 MIL-STD-810G w/Change 1을 기반으로 수립된 시험단계와 상세 프로파일에 대해 제안하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.120-123
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• 2005

This paper, for the establishment of power system models and test procedures for the dynamic performance test of transformer protective relay, presents power system model, environment establishement between RTDS and protective relay, and the dynamic performance test generated internal fault or external fault.

• Journal of the Korean Data and Information Science Society
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• 제6권2호
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• pp.9-15
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• 1995

In discriminant analysis the procedures commonly used to estimate the dimensionality involve testing a sequence of dimensionality hypotheses. There is a problem with the size of the test since dimensionality hypotheses are tested sequentially and thus they are actually conditional tests. The focus of this paper is "How is the size of the test affected by viewing this sequence of tests as conditional tests?".

• Journal of the Korean Data and Information Science Society
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• 제15권2호
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• pp.441-447
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• 2004

Li and Mak (1994) developed a test statistic for detecting the non-linearity and the heteroscedasticity of the time series data. But it is well known that the test statistic may be very sensitive in case of heavy-tailed distributions of the errors. Jiang et al.(2001) suggested the robust method for ARCH models but the calculation procedures for the estimation are very complicated. We suggested the robust method based on Huber's function and our method works quite well rater than the Li and Mak(1994). Also our method is relatively easy to calculate the test statistic.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.139-147
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• 2001

In this study a path control scheme of simulation models of various vehicles to evaluate their handling characteristic is developed. Based on the forward target method, path deviation error is estimated and the required steering effort to reduce the error is computed by Ziegler-Nichols PID control rule. Velocity control model is also included in the proposed path control scheme to achieve the desired velocity. The path control scheme is implemented on a full vehicle model to perform ISO test procedures, such as steady state cornering, lane change, and sinusoidal input, etc. Through the simulations of ISO test procedures and comparison with actual tests, effectiveness and validity of the path control model is demonstrated.

• 대한안전경영과학회지
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• 제12권1호
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• pp.199-205
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• 2010

The research proposes the three-factor random measurement models for estimating the precision about operator, part, tool, and various measurement environments. The combined model with crossed and nested factors is developed to analyze the approximate F test by degrees of freedom given by Satterthwaite and point estimation of precisions from expected mean square. The model developed in this paper can be extended to the three useful models according to the type of nested designs. The study also provides the three-step procedures to evaluate the measurement precisions using three indexes such as SNR(Signal-To-Noise Ratio), R&R TR(Reproducibility&Repeatability-To-Total Precision Ratio), and PTR(Precision-To-Tolerance Ratio), The procedures include the identification of resolution, the improvement of R&R reduction, and the evaluation of precision effect.

• Structural Engineering and Mechanics
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• 제8권1호
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• pp.1-18
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• 1999

Procedures are investigated by which nonlinear finite element shell analysis algorithms can be simplified to provide more cost effective approximate analyses of orthogonally-reinforced concrete flat plate structures. Two alternative effective stiffness formulations, and an unbalanced force formulation, are described. These are then implemented into a nonlinear shell analysis algorithm. Nonlinear geometry, three-dimensional layered stress analyses, and other general formulations are bypassed to reduce the computational burden. In application to standard patch test problems, these simplified approximate analysis procedures are shown to provide reasonable accuracy while significantly reducing the computational effort. Corroboration studies using various simple and complex test specimens provide an indication of the relative accuracy of the constitutive models utilized. The studies also point to the limitations of the approximate formulations, and identify situations where one should revert back to full nonlinear shell analyses.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2005년도 학술발표대회 논문집
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• pp.75-82
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• 2005

In this paper, accelerated life testing(ALT) method and procedures for a are developed and applied to assess the reliability of the product. Relay is a device that can open and close the electric circuit electrically and is used for protecting and controlling the load. In this study, an accelerated life test method for predicting the mechanical life of a relay is developed using the relationship between stresses, failure mechanism and life characteristics of products. Using the ALT method, we performed life tests and analyzed the tests results. The proposed method and procedures may de extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably.

• 항공우주시스템공학회지
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• 제9권3호
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• pp.8-11
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• 2015

Since the late 1990's, FAA, NASA and the aerospace industry have worked together to develop the sharing system of the composite material qualification databases which were obtained through the standardized fabrication and testing procedures. The result was what is now known as the AGATE(Advanced General Aviation Transport Experiments) or NCAMP(National Center for Advanced Materials Performance) methodology, a more cost-effective concept that shifts the major responsibility for qualification and testing from the aircraft manufacturer to the material supplier. The properties of composite materials are largely dependent on the testing as well as the raw material properties and the manufacturing process including the process control parameters. Thus it is important in the composite material qualification to comply with the standardized testing procedures. In this paper, I will describe the standardized witness methodologies of certification engineers to reduce the effect of testing variability within the qualification data.