• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.135-147
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• 1994

This study was conducted to evaluate whether the fatigue toughness of visible light cured composite resins could be improved and how much percentage of polymerzation shrinkage could be affected by additional heat treatment. 7 materials were investigated for this study: P-50, Lite-fil CR inlay, Pekafil, Clearfil CR inlay, Clearfil photo posterior, Z -100 and Progress. Diametral tensile strengths and linear shrinkages of composite resins were taken under visible light cured and additional post-cure heated condition and compared each other. A fatigue toughness of above materials was evaluated by measuring diametral tensile strength after they were repeatedly loaded with 120kgf/$cm^2$ up to 3000 cycles. The results obtained were as follows : 1. When composite resins were cured just by visible light, Lite fil CR inlay, Z -100 and Progress showed respectively higher diametral tensile strength than the other materials. Clearfil CR inlay, Clearfil photo posterior and Progress exhibited strong fatigue toughness compared to P-50 and Pekafil. 2. Post-cure heat treated composite resins had higher diametral tensile strengths than visible light cured composite resins at fatigue toughness test as well as no fatigue toughness test. 3. When Composite resins were additionally polymerized by post-cure heat treatment, P-50 showed weak fatigue toughness, on the contrary, Clearfil CR inlay, Z-100, Progress showed strong one. 4. When composite resins were cured just by visible light, percentage of polymerization linear shrinkage was the lowerest in Clearfil CR inlay, followed by, in ascending order, Clearfil photo posterior, Lite-fil CR inlay, Progress, Pekafil, P-50, and Z-100. In the case of post- cure heat treated composite resins, percentage of linear shrinkage was the lowest in Clearfil photo posterior, followed by, in ascending order, Lite-til CR inlay, Clearfil CR inlay, Progress, P-50, Pekafil and Z-100. 5. Percentage of polymerization linear shrinkage was greater in the post-cure heat treated composite resins than in the visible light cured composite resins and linear shrinkage increased significantly in Pekafil, Clearfil CR inlay, and Clearfil photo posterior between at the visible light cured and at the post-cure heat treated condition. The above results is saying that additional post-cure heat treatment on the composite resins for posterior restoration is able to affect on improvement of strength and fatigue toughness and lead to increase polymerization of composite resins.

• Journal of KSNVE
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• v.8 no.5
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• pp.964-973
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• 1998

In this paper we propose a levitation and imbalance compensation controller design methodology of magnetic bearing system. In order to achieve levitation and elimination of unbalance vibartion in some operation speed we use the discrete-time Q-parameterization control. When rotor speed p = 0 there are no rotor unbalance, with frequency equals to the rotational speed. So in order to make levitatiom we choose the Q-parameterization controller free parameter Q such that the controller has poles on the unit circle at z = 1. However, when rotor speed p $\neq$ 0 there exist sinusoidal disturbance forces, with frequency equals to the rotational speed. So in order to achieve asymptotic rejection of these disturbance forces, the Q-parameterization controller free parameter Q is chosen such that the controller has poles on the unit circle at z = $exp^{ipTs}$ for a certain speed of rotation p ( $T_s$ is the sampling period). First, we introduce the experimental setup employed in this research. Second, we give a mathematical model for the magnetic bearing in difference equation form. Third, we explain the proposed discrete-time Q-parameterization controller design methodology. The controller free parameter Q is assumed to be a proper stable transfer function. Fourth, we show that the controller free parameter which satisfies the design objectives can be obtained by simply solving a set of linear equations rather than solving a complicated optimization problem. Finally, several simulation and experimental results are obtained to evaluate the proposed controller. The results obtained show the effectiveness of the proposed controller in eliminating the unbalance vibrations at the design speed of rotation.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.69-81
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• 2010

This study was conducted at 25 sites of 6 mainstreams and 19 tributaries sites within Heuck Stream watershed during May~October 2003 for the survey of fish distributions, compositions, and community characteristics. The survey showed that total fish was identified as 9 family and 26 species in all sites, and Cyprinidae dominated the community as 15 species. The dominant species of >20% of the total were Zacco temminckii (29%), Zacco platypus (22%), and Rhynchocypris oxycephalus (21%) in the watershed. Community analysis, based on the stream spatial gradients, indicated composition differences along the main axis of the stream from the headwater to the downstream; R. oxycephalus predominated in the most headwater zone and Z. temminckii dominated in the lower headwater zone, whereas Z. temminckii -Z. platypus dominated in the mid-to-downstream, and Z. platypus dominated the community in the most downstream zone. Total endemic species was 7 family and 15 species, which is made of 50% in the fish community, so that the high proportion of endemic species indicated a healthy region in terms of fish community, compared to average 23% in Korean peninsula in general. The total number and species of fish increased as the stream order (stream size) increased, indicating that impacts on chemical pollution or habitat disturbance were not so large to the fish community in this watershed. Trophic and tolerance guilds analysis showed that relative proportions of sensitive and insectivore species were >50% in the watershed and decreased as the stream order increased, whereas relative proportions of tolerant and omnivore species showed an opposite results. These outcomes suggest that the natural condition of watershed is preserved relatively and the region should be protected from the chemical and habitat disturbace by agricultural activity and urban developments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.813-823
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• 1998

This paper analyzed the circularly polarized conformal microstrip patch antennal using the unsplit anisotropic perfectly matched layer(UAPML) method. Also, this paper are treated effectively the edge and corner parts on the 3 dimensional UAPML. Especially, to analyze microstrip patch antennas with the coaxial feeder line, it was applied to mixed the UAPML with Mur's first order absorbing boundary condition. Therefore this paper suggest the new the method to mix the UAPML with Mur's first order absorbing boundary condition. The results show the time responses of electromagnetics $E_z$ and $H\chi'$, input impedances of coaxial cable and radiation patterns of strip parchs on the single and the array patchs with central frequencies 1.575 GHz, 1.778 GHz and 4.8 GHz in L-band and C-band for mobile communication. The results of this paper shows that its results was compared the Mur's first order abc and mixed the second order dispersion boundary condition(SDBC) with the Mur's first order absorbing boundary condition. In accordance with, the validity of the method is confirmed.

• Journal of applied mathematics & informatics
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• v.17 no.1_2_3
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• pp.433-455
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• 2005

Fritz John, and Karush-Kuhn-Tucker type optimality conditions for a constrained variational problem involving higher order derivatives are obtained. As an application of these Karush-Kuhn-Tucker type optimality conditions, Wolfe and Mond-Weir type duals are formulated, and various duality relationships between the primal problem and each of the duals are established under invexity and generalized invexity. It is also shown that our results can be viewed as dynamic generalizations of those of the mathematical programming already reported in the literature.

• Honam Mathematical Journal
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• v.34 no.1
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• pp.1-9
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• 2012

The purpose of this paper is to give a new construction of the extended q-Euler numbers and polynomials of higher-order with weight by using p-adic q-integral on $\mathbb{Z}_p$.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1597-1612
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• 2016

There are fruitful results on degenerate parabolic-hyperbolic equations recently following the idea of $Kru{\check{z}}kov^{\prime}s$ doubling variables device. This paper is devoted to the well-posedness of nonhomogeneous boundary problem for degenerate parabolic-hyperbolic equations with spatially dependent second order operator, which has not caused much attention. The novelty is that we use the boundary flux triple instead of boundary layer to treat this problem.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.153-160
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• 2007

In this paper, the exact analysis of the parallel coupled line with open stub is presented. This structure shows LPF characteristics with broad stopband and sharp skirt characteristics. We derived the exact Z-matrix expression of the structure. In order to show the validation of the expression we designed $3^{th}$ order Chebyshev LPF using the structure. The simulated data excellently agreed with the predicted values by the calculation using the derived expression.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.137-141
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• 1996

A new general high order consistent nodal method for solving the 3-D multigroup neutron kinetic equations in (x-y-z) geometry has been derived by expending the flux in a multiple polynomial series for the space variables by without the quadratic fit approximations of the transverse leakage and for the time variable and using a weighted-integral technique. The derived equation set is consistent mathematically, and therefore, we can expect very accurate solutions and less computing time since we can use coarse meshes in time variable as well as in spatial variables and the solution would converge exactly in fine mesh limit.

• Honam Mathematical Journal
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• v.37 no.2
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• pp.265-267
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• 2015

Let G be a cyclic group of prime power order. There is a natural embedding of $\mathbb{Z}$[G] into a product of rings of integers of cyclotomic fields. In this paper we determine the image of powers of the augmentation ideal.