• Korean Journal of Crystallography
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• 제17권2호
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• pp.51-54
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• 2006

BaO layers were formed on the Si(100) surface by thermal evaporation of barium metal with simultaneous oxidation. The atomic structure of BaO layers at the initial stage of the deposition was investigated by the scattering intensity variation of $He^+$ions on time-of-flight (TOF) impact-collision ion scattering (ICISS). The results show that several number of BaO layers are formed on the Si(100) surface with the lattice parameter of bulk phase, and the occupation of oxygen atoms of the BaO layers is on-top site of silicon atoms.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(3)
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• pp.173-176
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• 2001

This paper proposes training algorithms of neuro-fuzzy systems. First, we introduce a structure training algorithm, which produces the necessary number of hidden nodes from training data. From this algorithm, initial fuzzy rules are also obtained. Second, the parameter training algorithm using evolution strategy is introduced. In order to show their usefulness, we apply our neuro-fuzzy system to a nonlinear system identification problem. It was found from experiments that proposed training algorithms works well.

• Journal of Ocean Engineering and Technology
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• 제15권3호
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• pp.43-48
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• 2001

In this paper, the real-time prediction of high temperature creep strength and creep for nickel-based superalloy Udimet 720 (high-temperature and high-pressure gas turbine engine materials) was performed on round-bar type specimens under pure load at the temperatures of 538, 649 and 704$^{\circ}C$. The predictive equation of ISM creep has better reliability than that of LMP and LMP-ISM, and its reliability is getting better for long time creep prediction ($10^3~10^5$h).

• Journal of the Korean Institute of Intelligent Systems
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• 제2권2호
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• pp.34-41
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• 1992

A robust and reliable learning and reasoning mechanism is addressed based upon fuzzy set theory and fuzzy associative memories. The mechanism stores a priori an initial knowledge base via approximate learning and utilizes this information for decision-making systems via fuzzy inferencing. We called this fuzzy computer architecture a 'fuzzy hypercube' processing all the rules in one clock period in parallel. Fuzzy hypercubes can be applied to control of a class of complex and highly nonlinear systems which suffer from vagueness uncertainty. Moreover, evidential aspects of a fuzzy hypercube are treated to assess the degree of certainty or reliability together with parameter sensitivity.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.245-250
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• 1995

Steel effects on creep deformation of prestressed concrete structues are investigated by a parametric study. Prestressed steel ratio, Prestressed steel distribution, initial flexural stress gradient, and modular ratio are selected as parameters. Sectional analysis for the beam section of parameter combination is performed to find curvatrue change due to creep. Based on the investigation, long-term curvature formulas from regression analysis are proposed. Application of the furmulas to simply supported prostressed concrete beam shows the effect of steel on deflection.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 한국퍼지및지능시스템학회 2001년도 추계학술대회 학술발표 논문집
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• pp.233-236
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• 2001

In this paper, we propose a TSK-type fuzzy classifier using PCA(Principal Component Analysis), FCM(Fuzzy C-Means) clustering and hybrid GA(genetic algorithm). First, input data is transformed to reduce correlation among the data components by PCA. FCM clustering is applied to obtain a initial TSK-type fuzzy classifier. Parameter identification is performed by AGA(Adaptive Genetic Algorithm) and RLSE(Recursive Least Square Estimate). we applied the proposed method to Iris data classification problems and obtained a better performance than previous works.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제6권1호
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• pp.91-107
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• 2002

This paper presents two new self-scaling variable-metric algorithms. The first is based on a known two-parameter family of rank-two updating formulae, the second employs an initial scaling of the estimated inverse Hessian which modifies the first self-scaling algorithm. The algorithms are compared with similar published algorithms, notably those due to Oren, Shanno and Phua, Biggs and with BFGS (the best known quasi-Newton method). The best of these new and published algorithms are also modified to employ inexact line searches with marginal effect. The new algorithms are superior, especially as the problem dimension increases.

• Communications for Statistical Applications and Methods
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• 제5권3호
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• pp.895-904
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• 1998

Two stage shrinkage testimator is a kind of adaptive estimators based on a test on an initial estimate of parameter. Since weighing factor plays an important roll in assessing the properties of testimator, its choice is extremely crucial in two stage testimation. Adke, Waikar and Schuurmann(1987) proposed a testimator for the mean of an exponential distribution defined with their own weighing factor. Two alternative testimators obtained using changed weighing factors are presented, and their Mean squared error(MSE) formulae are provided in this paper. Their properties are compared with those of existing one by means of MSE.

• Journal of the Korean Institute of Telematics and Electronics
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• 제11권3호
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• pp.27-31
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• 1974

The maximum principle of Pontryagin provides the celebrated method to obtain the optimum control switching time and switching points on the nuclear reactor. The control trajectories transfered from its initial state to the target state are optimized based on time optioptimal control method with the given reactor parameters and the piecewise constant input values.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.479-484
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• 2000

The reliable estimation of the system parameters and the accurate prediction of the system behavior are important to design tunnel safely and economically. Therefore, the back analysis using the field measurements data is useful to evaluate the geotechnical parameter for tunnel. In the back analysis method, the selection of initial value and uncertainty of field measurements influence significantly on the analysis result. In this paper, to overcome uncertainty of field measurements, we performed the back analysis using the displacement data gained at each step of excavation and support.