• Journal of the Korean Mathematical Society
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• v.33 no.2
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• pp.227-234
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• 1996

Consider nonlinear autoregressive processes of order 1 defined by the random iteration $$ (1) X_{n + 1} = f(X_n) + \epsilon_{n + 1} (n \geq 0) $$ where f is real-valued Borel measurable functin on $R^1, {\epsilon_n : n \geq 1}$ is an i.i.d.sequence whose common distribution F has a non-zero absolutely continuous component with a positive density, $E$\mid$\epsilon_n$\mid$ < \infty$, and the initial $X_0$ is independent of ${\epsilon_n : n > \geq 1}$.

• Journal of Radiation Protection and Research
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• v.23 no.3
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• pp.159-174
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• 1998

Personal dosimetry system is required to measure the personal dose equivalent accurately in a wide range of radiation fields, but the dose evaluation algorithms have been developed with the X-ray fields described in MOST Ordinance (equivalent to the ANSI N13.11) from which the actual fields to be monitored may be significantly different. To evaluate the dose more accurately when workers are exposed to the non-ANSI N13.11 radiation fields, two algorithms for monochromatic radiations (one algorithm was used for various ratios of TL dosimeter and the other for matrix approximation) were developed with the experimental data of the energy responses of the $CaSO_4:Dy$ TL materials irradiated by monochromatic X-ray fields recently established in KAERI, and compared with the another algorithm developed on the basis of the ANSI N13.11 continuous spectrum X-ray fields. Then it follows the discussions for some results of the algorithm testing including mixed fields irradiations and angular response conducted in IAEA/RCA intercomparison as well as ANSI and ISO continuous spectrum X-ray and monochromatic radiation fields. The developed algorithms were successfully performed the test not only in the continuous spectrum X-ray fields given by MOST Ordinance but also in the several non-MOST Ordinance radiation fields which could be encountered in the practical working environments.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.2 no.2
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• pp.49-56
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• 1998

In this paper, by the use of an Ostrowski type integral inequality for double integrals, we establish an upper bound for the estimation error variance of a continuous stream with stationary variogram.

• Journal of applied mathematics & informatics
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• v.6 no.2
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• pp.407-416
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• 1999

In this paper we give some sufficient conditions for the existence and uniqueness of a continuous for the existence and uniqueness of a continuous slution of the system of Urysohn-Volterra equation with hysteresis.

• Journal of applied mathematics & informatics
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• v.5 no.3
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• pp.805-810
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• 1998

In this paper we set the stock price model in security market when the price process is a continuous semartingale and find a unigue solution of price process model.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.325-326
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• 2006

Using $6wt%Y_2O_3-2wt%Al_2O_3$ as sintering additives and Si as a raw powder, the continuously porous in-situ $Si_2N_2O-Si_3N_4$ bodies were fabricated by multi-pass extrusion process and their microstructures were investigated depending on the addition of carbon (0-9wt%) in the mixture powder. The introduction of $Si_2N_2O$ fibers observed in the unidirectional continuous pores as well as in the pore-frame regions of the nitrided bodies can be an effective method in increasing the filtration efficiency. In the case of no carbon addition, the network type $Si_2N_2O$ fibers with high aspect ratio appeared in the continuous pores with diameters of 150-200 nm. However, in the case of 9wt% C addition, the fibers were found without any network type and had diameters of 200-250 nm.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.4 no.1
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• pp.93-100
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• 2000

This paper deals with some fundamental matters pertaining to estimation of critical quantities associated with continuous processes which are frequently related to the quality rating of the product. Specifically, it examines bounds on estimation and bounds on the estimation error variance. It draws on recent results from the theory of mathematical inequalities and their applications.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.4 no.1
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• pp.101-107
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• 2000

In this paper we establish an upper bound for the estimation error variance of a continuous stream with a stationary variogram V which is assumed to be of the r-Holder type (Lipschitzian) on [-d, d]. Functional properties for the mapping ${\xi}(t):=E[(X-X(t))^2]$, $t{\in}[0,d]$, are also given.

• Kyungpook Mathematical Journal
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• v.50 no.1
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• pp.15-35
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• 2010

By strengthening dichotomy condition and weakening decay conditions, we show that a four term 2n-th order differential operator with unbounded coefficients is nonlimit-point. Using stringent conditions we show that the deficiency index of this operator is determined by the behaviour of the coefficients themselves. Similarly, we prove the absence of singular continuous spectrum and that the absolutely continuous spectrum has multiplicity two.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.355-367
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• 2006

In this paper, we consider the oscillation second order unstable neutral difference equations with continuous arguments $\Delta^2_{/tau}(\chi(t)-p\chi(t-\sigma))=f(t,\chi(g(t)))$ and obtain some criteria for the bounded solutions of this equation to be oscillatory.