• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.64-71
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• 2013

In this study we designed a lean $NO_x$ trap (LNT) model with $GT-POWER^{TM}$ program and then the LNT model was compared to the bench flow reactor test results. This model consists of 9 kinetic reactions to represent the main steps of NO oxidation, $NO_x$ adsorption, $NO_x$ release and then its reduction. The comparison was performed on the operating conditions at the space velocity of 50,000 1/hr and 80,000 1/hr with the temperature range of $200^{\circ}C{\sim}500^{\circ}C$ with the even spaced temperature step of $50^{\circ}C$. The experimental results show that the $NO_x$ conversion efficiency was enhanced by the temperature up to $350^{\circ}C$ and then decayed at higher temperatures. The LNT model predicts the similar trend of the $NO_x$ conversion efficiency to the experimental results below $350^{\circ}C$, but overestimates above $350^{\circ}C$. This overestimation comes from the higher reduction efficiency which was obtained by the different reduction gas composition such as $C_3H_6$ in the model to replace $CH_4$, $C_2H_4$ in the bench test.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1696-1701
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• 2007

This paper presents a micro-mechanical model of ductile fracture for the API X65 steel using the Gurson-Tvergaard-Needleman (GTN) model. Experimental tests and FE damage simulations using the GTN model are performed for smooth and notched tensile bars, from which the parameters in the GTN model are calibrated. As application, the developed GTN model is applied to simulate small-sized, single-edge-cracked tensile and bend bars, via three-dimensional FE damage analyses. Comparison of FE damage analysis results with experimental test data shows overall good agreements.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1315-1318
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• 2003

In this paper, a neural network based approach using a self-organizing feature map is proposed for the segmentation of X ray images. A number of algorithms based on such approaches as histogram analysis, region growing, edge detection and pixel classification have been proposed for segmentation of general images. However, few approaches have been applied to X ray image segmentation because of blur of the X ray image and vagueness of its edge, which are inherent properties of X ray images. To this end, we develop a new model based on the neural network to detect objects in a given X ray image. The new model utilizes Mumford-Shah functional incorporating with a modified adaptive SOFM. Although Mumford-Shah model is an active contour model not based on the gradient of the image for finding edges in image, it has some limitation to accurately represent object images. To avoid this criticism, we utilize an adaptive self organizing feature map developed earlier by the authors.[1] It's learning rule is derived from Mumford-Shah energy function and the boundary of blurred and vague X ray image. The evolution of the neural network is shown to well segment and represent. To demonstrate the performance of the proposed method, segmentation of an industrial part is solved and the experimental results are discussed in detail.

• Convergence Security Journal
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• v.12 no.6
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• pp.51-59
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• 2012

This paper presents a new learning model, "BoX(Battle of X)", which is based on a concept from the culture of B-Boys who enjoy the race of "distributed cognition" to win in their contests. The "battle" means a contest and "X" means a course to which our learning model can be applied. The goal of this paper is to present a learning model that allow students to be in a state of learning-flow and provides them with the ability of creative problem solving simultaneously. The key of the "BoX" implementation is to design a principle that controls contests between students to maximize distributed cognitive activities for reducing individual's cognitive load. This paper also presents how-to of "BoX" implementation and its effects. Through the analysis on learning achievement of students during one year course of IT education, we have confirmed that the "BoX" model provides students with higher learning achievement and learning-flow level in comparison with traditional learning model.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.42-48
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• 1992

RoA is an important figure of merits for estimating the performance of p-n junction infrared detectors. This paper presents the tunneling current contribution to RoA of $Hg_{1-x}Cd_{x}$Te n$^{+}$-p juction photodiodes. Then, a diffusion model, a thermal generation-recombination model, an indirect tunneling model via trap, and a band-to-band direct tunneling model are considered to calculate RoA. Using these models, RoA depending on temperature, doping concentration, and mole fraction is calculated. Also from these results, under various operating conditions the dominant dark current mechanisms cna be understood.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.3
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• pp.641-645
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• 2013

In this article, we show that the modular equation ${\Phi}_p^{T_q}(X,Y)$ of Thompson series $T_q$ corresponding to ${\Gamma}_0(q)+q$ gives an affine model of a modular curve $X_0(pq)+q$.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.179-186
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• 1992

This experiment was carried out to study the drying characteristics of model foods containing moisture, protein and starch on different concentration of additives such as sodium chloride and sucrose. Textural properties of model foods were measured by using UTM(instron). The results obtained are summaried as follows: As starch content and solute concentration of model foods increase, drying time was extended. The multiple regression equations for drying characteristics of additive concentration ($X_1$, %), drying time ($X_3$, hr), drying temperature ($X_2$, OC), starch content($X_4$, %) are : $$E(MC)=58.282-5.197X_3-15.151X_4-0.145X_2+2.672X_1\;R^2=0.798\;(NaCl)$$ $$E(MC)=56.651-7.253X_3-0.183X_2-42.844X_1+3.025X_4\;R^2=0.858\;(Sucrose)$$ As starch content, drying temperature and solute concentation increased, he hard ness of model foods increased.

• Journal of the Korean Data and Information Science Society
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• v.28 no.3
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• pp.697-707
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• 2017

In this paper, we propose a modified GARCH(p, q)-X model which is obtained by adding the exogenous variables to the modified GARCH(p, q) process. Some limiting properties are shown under various stationary and nonstationary exogenous processes which are generated by another process independent of the noise process. The proposed model extends the GARCH(1, 1)-X model studied by Han (2015) to various GARCH(p, q)-type models such as GJR GARCH, asymptotic power GARCH and VGARCH combined with exogenous process. In comparison with GARCH(1, 1)-X, we expect that many stylized facts including long memory property of the financial time series can be explained effectively by modified GARCH(p, q) model combined with proper additional covariate.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.2
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• pp.17-22
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• 2008

To develop an imaging optical system for the 545 nm fluorescent plate of X-ray. Methods: We designed and manufactured a new imaging optical system for the 545 nm fluorescent plate of X-ray by Sigma 2000 program after deciding the design comparison standards referred to Canon CX2-70 model. Results: The characteristics of the new imaging optical system for the 545 nm fluorescent plate of X-ray have the magnification of -0.225x, the image field size of $90mm{\times}90mm$, and the 0.033 mm resolution line width at the 30% MTF value criterion. These mean that the new model has a capability of deciphering for the more large screen and the resolution of deciphering is superior to that of Canon CX2-70 model. Also the image side NA (-0.196) of the new model is about $\sqrt{2}$ times than that (-0.139) of CX2-70 and the object side NA (0.044) of the new model is about 2 times than that (0.022) of CX2-70. These mean that the sensitivity of the film in the new design model is able to be increased to about 4 times and there is the possibility of reducing the bombed time of X-ray to 1/4 times. Conclusions: We could design and manufacture the imaging optical system for the 545 nm fluorescent plate of X-ray having the possibility of reducing the bombed time of X-ray to 1/4 times in comparision to Canon CX2-70 model, the characteristics of which have the image field size of $90mm{\times}90mm$ and the MTF of 30% or more at 15 lines/mm criterion.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.37-42
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• 2001

This paper computes the bluff-body stabilized jet and flame. This study numerically investigates the nonpremixed $C_{2}H_{4}-air$ jet for the nonreacting case and the nonpremixed $CH_{3}OH-air$ turbulent flames for the reacting case using the laminar flamelet model on modified KIVA2 code. And this study predicts $NO_{x}$ formation characteristics using Eulerian Particle Flamelet Model. In the present study, the turbulent combustion model is applied to analyze both nonreacting and reacting case. And both standard $k-{\varepsilon}$ model and modified $k-{\varepsilon}$ model are used in nonreacting case. Calculations are compared with experimental data in terms of velocity, mixture fraction, mixture fraction Root Mean Square and Temperature. The present model correctly predicts the essential features of flame structures and $NO_{x}$ formation characteristics in the bluff-body stabilized flames.