• 통합자연과학논문집
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• 제6권2호
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• pp.111-117
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• 2013

We propose a mean value function for software failures in NHPP software reliability model. And we deal with the maximum likelihood estimation and the least squares estimation in the proposed mean value function. The explicit mean value function solution for the proposed model is presented by MLE and LSE in two data sets. The values of SSE and MSE is presented in two data sets by MLE and LSE. We compare the predicted number of faults with the actual two data sets using the proposed mean value function.

• Structural Monitoring and Maintenance
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• 제9권2호
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• pp.157-177
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• 2022

In this paper, an innovative finite element updating method is presented based on the variation wavelet transform coefficients of Auto/cross-correlations function (WTCF). The Quasi-linear sensitivity of the wavelet coefficients of the WTCF concerning the structural parameters is evaluated based on incomplete measured structural responses. The proposed algorithm is used to estimate the structural parameters of truss and plate models. By the solution of the sensitivity equation through the least-squares method, the finite element model of the structure is updated for estimation of the location and severity of structural damages simultaneously. Several damage scenarios have been considered for the studied structure. The parameter estimation results prove the high accuracy of the method considering measurement and mass modeling errors.

• Smart Structures and Systems
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• 제10권4_5호
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• pp.427-442
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• 2012

An effective approach for updating finite element model is presented which can provide reliable estimates for structural updating parameters from identified operational modal data. On the basis of the dynamic perturbation method, an exact relationship between the perturbation of structural parameters such as stiffness change and the modal properties of the tested structure is developed. An iterative solution procedure is then provided to solve for the structural updating parameters that characterise the modifications of structural parameters at element level, giving optimised solutions in the least squares sense without requiring an optimisation method. A regularization algorithm based on the Tikhonov solution incorporating the generalised cross-validation method is employed to reduce the influence of measurement errors in vibration modal data and then to produce stable and reasonable solutions for the structural updating parameters. The Canton Tower benchmark problem established by the Hong Kong Polytechnic University is employed to demonstrate the effectiveness and applicability of the proposed model updating technique. The results from the benchmark problem studies show that the proposed technique can successfully adjust the reduced finite element model of the structure using only limited number of frequencies identified from the recorded ambient vibration measurements.

• Nuclear Engineering and Technology
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• 제4권4호
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• pp.280-293
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• 1972

원자로(TRIGA MARK-II)노심의 특정위치에서 0.5 Mev 이상의 고속중성자 스펙트럼을 발단검출기(Threshold detector)를 사용하여 실험적으로 측정하였다. 발단검출기의 실험적인 방사화자료로서 결정되는 일련의 적분방정식에 대한 근사해를 얻기 위하여 최소자승법의 개념을 이용한 급수전개법을 사용하였다. 상이한 가중함수 (weighting function)를 사용하므로서 해답에 미치는 영향을 각측정에서 분석 검토하였다. 이방법의 사용에 관련되는 수치계산을 수행하기 위하여 UNIVAC 1106전자계산기를 위한 계산코드를 준비하였다. 본 연구에서 얻은 미분적 고속중성자 스펙트럼은 독립적으로 다군 수송이론에 의하여 얻은 결과와 잘 일치하였다.

• 약학회지
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• 제47권6호
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• pp.461-468
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• 2003

A method is described for measuring clinically relevant levels of glucose in a pH 7.4 phosphate buffer by nearinfrared (NIR) absorption spectroscopy. Three types of NIR spectrometer, dispersive type, photo-diode array (PDA) type, and fourier transform (FT) type spectrometer were used and the performance was compared. Spectra were collected with a cuvette cell or quartz liquid fiber of 1 mm or 2 mm optical pathlength as transmittance method. Glucose absorption band appeared at second overtone, first overtone, and combination region for all systems. By use of the multivariate technigue of partial least squares (PLS) regression, glucose concentrations can be determined with a 16, 44, and 9.1 mg/d l standard error of prediction for dispersive type, photo-diode array type, and fourier transform type system, respectively. Sensitivity of spectrometer was evaluated by absorbance for the difference of 10 mg/d l glucose. Three absorption bands, second overtone, first overtone, and combination region were suited to three types systems, dispersive type, photo-diode array type, and fourier transform type systems, respectively. This investigation showed that three types NIR spectrometer were proper method for identification and quantitative analysis of glucose and possible for noninvasive blood glucose monitoring.

• Steel and Composite Structures
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• 제49권4호
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• pp.407-417
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• 2023

After a disaster like the catastrophic earthquake, the government have to use rapid assessment of the condition (or damage) of bridges, buildings and other infrastructures is mandatory for rapid feedbacks, rescue and post-event management. Many domain schemes based on the measured vibration computations, including least squares estimation and neural fuzzy logic control, have been studied and found to be effective for online/offline monitoring of structural damage. Traditional strategies require all external stimulus data (input data) which have been measured available, but this may not be the generalized for all structures. In this article, a new method with unknown inputs (excitations) is provided to identify structural matrix such as stiffness, mass, damping and other nonlinear parts, unknown disturbances for example. An analytical solution is thus constructed and presented because the solution in the existing literature has not been available. The goals of this paper are towards access to adequate, safe and affordable housing and basic services, promotion of inclusive and sustainable urbanization and participation, implementation of sustainable and disaster-resilient buildings, sustainable human settlement planning and manage. Simulation results of linear and nonlinear structures show that the proposed method is able to identify structural parameters and their changes due to damage and unknown excitations. Therefore, the goal is believed to achieved in the near future by the ongoing development of AI and control theory.

• 경영정보학연구
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• 제25권2호
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• pp.163-180
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• 2023

본 연구는 TOE(Technology-Organization-Environment) 모델을 기반으로 원격근무 솔루션(RWS)의 기술적, 조직적, 환경적 측면을 고려해 위드 코로나 시대 이용자들의 지속사용 의도를 설명할 수 있는 연구 모형을 제안하였다. 연구 모형 및 가설 검증을 위해 국내 원격근무 솔루션 사용자를 대상으로 온라인 설문을 실시하였고 부분최소자승법(Partial Least Square, PLS)을 이용해 411개 수집 데이터를 분석하였다. 분석 결과, 기능성과 보안성은 생산성 향상과 만족도에 모두 유의한 양의 상관관계가 있음이 밝혀졌다. 또한 조직 준비성은 생산성 향상에 긍정적인 영향을 끼치나 만족도에는 영향을 주지 못하는 것으로 드러났다. 정부지원은 원격근무 솔루션의 지속사용의도에 긍정적인 영향을 미치는 것이 확인되었으나 건강에 대한 우려와 지속사용의도와의 상관관계는 유의하지 않은 것으로 나타났다. 마지막으로 생산성 향상과 만족도, 지속사용의도 간의 상관관계들은 모두 유의한 것으로 확인되어 총 11개 가설 중 9개 가설이 지지되었다.

• 한국전산구조공학회논문집
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• 제37권1호
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• pp.41-47
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• 2024

본 논문에서는 전산점근해석기법을 사용하여 복합재료 보에 대한 경계층 해를 계산하고, ANSYS 결과와 비교 검증하였다. 경계층 해는 내부해와 순수 경계층 효과의 합으로 표현되기 때문에, 내부 및 경계층에 대한 수학적으로 엄밀한 정식화를 요구한다. 전산점근 해석기법은 수학적으로 매우 강력한 기법으로, 이러한 문제에 유용하다. 그러나 경계층과 내부 해들의 연결을 시키기 쉽지 않은데, 본 연구에서는 가상일의 원리를 통해 생브낭의 원리와 내부 및 경계층 문제를 체계적으로 분리하였다. 경계층 해는 팝코비치-패들 고유벡터를 계산하여, 실수부와 허수부 벡터들의 선형 조합으로 표현하고, 내부 해의 워핑 함수들을 보상할 수 있도록 최소오차 자승법을 적용하였다. 계산된 해들은 2차원 유한요소 해석 결과와 비교하여 정성적일 뿐만 아니라 정량적으로도 잘 일치하는 결과를 얻었다.

• Nuclear Engineering and Technology
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• 제14권3호
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• pp.103-109
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• 1982

여러가지 질산우라늄용액에 대한 우라늄의 용존농도, 질산의 노르말농도 및 용액의 밀도등을 측정하여 얻은 결과를 최소자승법으로 분석한 후 우라늄의 용존농도와 질산의 노르말농도만을 알므로서 질산우라늄용액속에 들어있는 물의 함량을 결정할 수 있는 실험식, Q=1-0.3628C-0.0327H$^{+}$,을 유도하였다. 여기서 Q, C 및 H$^{+}$는 각각 물함량(g/cc), 우라늄의 용존농도(g/cc)및 질산의 노르말농도를 뜻한다. 그리고 이 유도식을 써서 임의 우라늄용액에 대한 구성원소별 원자수밀도와 핵임계도를 산출하고 그 결과를 우라늄의 용존농도, 질산의 노르말농도 및 용액의 밀도를 근거로 하여 얻은 값과 비교해 보았다. 그 결과 유도식은 우라늄의 용존농도 0.004~0.2959g/cc 및 질산의 노르말농도 1.00~5.06사이에서 유용하게 쓰일 수 있을 것으로 보였다.

• Smart Structures and Systems
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• 제9권3호
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• pp.253-271
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• 2012

Finite element (FE) model updating is a useful tool for global damage detection technique, which identifies the damage of the structure using measured vibration data. This paper presents the application of a finite element model updating method to detect the damage of a small-scale reinforced concrete building structure using measured acceleration data from shaking table tests. An iterative FE model updating strategy using the least-squares solution based on sensitivity of frequency response functions and natural frequencies was provided. In addition, a side constraint to mitigate numerical difficulties associated with ill-conditioning was described. The test structure was subjected to six El Centro 1942 ground motion histories with different Peak Ground Accelerations (PGA) ranging from 0.06 g to 0.5 g, and analytical models corresponding to each stage of the shaking were obtained using the model updating method. Flexural stiffness values of the structural members were chosen as the updating parameters. In model updating at each stage of shaking, the initial values of the parameter were set to those obtained from the previous stage. Severity of damage at each stage of shaking was determined from the change of the updated stiffness values. Results indicated that larger reductions in stiffness values occurred at the slab members than at the wall members, and this was consistent with the observed damage pattern of the test structure.