• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.161-164
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• 2004

A finite volume numerical model is developed for simulating non-equilibrium electroosmotic flow in micro- and nanochannels. The Guoy-Chapman model is adopted to compute the flow and electric potential. The Nernst-Planck equation is employed to trace unsteady transports of ionic species, i.e., time-dependent net charge density. A new set of boundary conditions based on surface charge density are designed rather than using the conventionally-employed zeta potential. A few issues for an efficient computation of electroosmotic flows are discussed. Representative computational examples are given to illustrate the robustness of the numerical model.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.6
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• pp.729-738
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• 2004

Seasonal variation of major inorganic ions in the greater Seoul area was estimated using a photochemical box model and a gas/aerosol equilibrium model with emphasis on semi -volatile nitrate. Pollutant emission was determined by season by comparing the predicted concentration with the measurement one obtained for a year from the late 1996. The results showed that particulate nitrate was the highest in summer but about 40% of total nitrate was present in the gas phase. This was due to volatilization at high temperature since ammonia was sufficient to neutralize all nitrate regardless of season. As relative humidity in summer was higher than the deliquescence point, particulate ion concentration with water was two times higher than that in other season. So called ‘NOx disbenefit’ indicating increase in particulate ion concentration with decrease in NOx emission was evident especially in winter.

• Carbon letters
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• v.23
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• pp.30-37
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• 2017

Dyes are widely used in various industries including textile, cosmetic, paper, plastics, rubber, and coating, and their discharge into waterways causes serious environmental and health problems. Four different carbon nanostructures, graphene oxide, oxidized multi-walled carbon nanotubes, activated carbon and multi-walled carbon nanotubes, were used as adsorbents for the removal of Nile Blue A (NBA) dye from aqueous solution. The four carbon nanostructures were characterized by scanning electron microscope and X-ray diffractometer. The effects of various parameters were investigated. Kinetic adsorption data were analyzed using the first-order model and the pseudo-second-order model. The regression results showed that the adsorption kinetics were more accurately represented by the pseudo-second-order model. The equilibrium data for the aqueous solutions were fitted to Langmuir and Freundlich isotherms, and the equilibrium adsorption of NBA was best described by the Langmuir isotherm model. This is the first research on the removal of dye using four carbon nanostructures adsorbents.

• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1073-1088
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• 2010

In this article we want to formulate a disease transmission model, MSEIR model, for a population with individuals travelling between patches i and i + 1 and we derive an explicit formula for the basic reproductive number, $R_0$, employing the spectral radius of the next generation operator. Also, in this article we show that a system of ordinary differential equations for this model has a unique disease-free equilibrium and it is locally asymptotically stable if $R_0$ < 1 and unstable if $R_0$ > 1.

• ETRI Journal
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• v.32 no.4
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• pp.530-539
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• 2010

As the conventional silicon metal-oxide-semiconductor field-effect transistor (MOSFET) approaches its scaling limits, quantum mechanical effects are expected to become more and more important. Accurate quantum transport simulators are required to explore the essential device physics as a design aid. However, because of the complexity of the analysis, it has been necessary to simulate the quantum mechanical model with high speed and accuracy. In this paper, the modeling of double gate MOSFET based on an adaptive neuro-fuzzy inference system (ANFIS) is presented. The ANFIS model reduces the computational time while keeping the accuracy of physics-based models, like non-equilibrium Green's function formalism. Finally, we import the ANFIS model into the circuit simulator software as a subcircuit. The results show that the compact model based on ANFIS is an efficient tool for the simulation of nanoscale circuits.

• Environmental and Resource Economics Review
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• v.5 no.1
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• pp.1-39
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• 1995

본 연구는 에너지정책을 종합적 차원에서 일반경제정책과 병행하여 정량적으로 분석할 수 있는 수리모형 (numerical multi-sector general equilibrium model)을 개발하기 위하여 시도되었다. 모형은 크게 (i) 가격/기술변화 반응적인 투입-산출계수를 내생화한 "산업간 거래모형 (inter-industry production model)", (ii) 민간에 의한 최종부문 수요를 나다내는 "소비자 선택모형 (consumer choices model)", 그리고 (iii) 생산물시장과 본원적 투입요소시장, 수출입시장 등에서 민간기업 정부 및 해외라는 개별 경제주체간의 행태를 반영하는 "거시경제 (성장) 모형 (macro-econometric growth model)"으로 구성되어 있다. 이러한 방법은 분석경제를 충분히 세분하고 제(諸)경제변수들의 동시결정적 과정을 중시한 일반균형적 /부문적 접근방법 (general equilibrium/sectoral approaches)을 취함으로써 지금까지 단순한 거시경제모형(aggregate macroeconomic models)이나 전통적 산업연관모형 (static input-output models)에만 의존해 오던 경제예측이나 경제 및 에너지관련 정책의 효과분석이 한층 더 강화될 수 있을 것으로 기대된다.

• Journal of applied mathematics & informatics
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• v.41 no.5
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• pp.1017-1035
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• 2023

In this paper, we construct a monkeypox model which is similar to smallpox infection. It is caused by a monkeypox virus which is related to Poxviridae family. It will occur mostly in West African communities and in remote Central. We develop a system of differential equations for an SEIR (Suspected, Exposed, Infected and Recovered) model and analyze the outbreak of monkeypox disease and its effect on United States(US) population. We establish theorems on asymptotical stability conditions for endemic equilibrium and disease-free equilibrium. The basic reproduction number R₀ has been determined using next generation matrix. We expect that this study will be effective at controlling monkeypox spread in United States. Our goal is to see whether monkeypox can be controlled and destroyed by smallpox vaccination. We find that monkeypox is controllable and can be fully destroyed in disease free state by vaccination. However, in the endemic state, monkeypox cannot be destroyed by vaccination alone.

• Journal of the Korean Regional Science Association
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• v.34 no.3
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• pp.43-54
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• 2018

This paper analyzes the effects of population aging on regional differentiation from the New Economic Geography perspective. The addition of old-age population variable affects the price index, income, nominal wage, and real wage derived in the short-run equilibrium. Using the new model, we can better explain industrial agglomeration patterns corresponding to the new long-run equilibrium. As the real wage criterion does not properly take the old-age group into account, we employ the indirect utility function as an additional condition for equilibrium. We further consider tax as a policy tool for achieving a better long-run equilibrium. This would enable the government to direct the economy toward a particular equilibrium desired in the face of population aging.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.87-96
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• 2009

The purpose of this paper is to analyze the power control problem in wireless communications with game theoretic approach. The major contribution of the present paper is that we formulated the problem as a game with a finite number of strategies while most of the previous game theoretic power control literatures modeled with continuous game in which there are infinite number of strategies. It should be noted that the closed-loop power control would be performed in a discrete manner, power up or down from the present level of power with fixed power control step size. We model the current closed-loop power control scheme with the famous Prisoner's dilemma model and show that the power-up strategy is Nash equilibrium. That is, every mobile tries to increase their power and approach to their maximal power. Thus, the outcome of current power control (Nash equilibrium) is inefficient. In order to attain efficient power control for the environment where ICI(Inter-Cell Interference is severe, we developed a new payoff function in which the penalty mechanism is introduced and derived conditions under which power-down becomes Nash equilibrium strategy for all players. Furthermore we examined the trajectory of equilibrium power when the power control game will be played repeatedly.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.1
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• pp.19-32
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• 2002

This paper examines the effect of the producer-supplier quality contract parameters and the magnitude of the quality related variables on the quality of the final products. Our analysis focuses on the parties' equilibrium behavior In a quality game environment where the supplier should choose among the two production technologies, one requiring high cost but producing high quality Parts and the other requiring low cost but producing low quality parts and where the producer should decide whether to do the inspection of the parts. The game framework is employed to depict the potential conflicts existing between the Producer and the supplier because the Producer can not observe the supplier's choice and each party wants the other to bear the cost of producing high quality products. In our model, we specifically consider the competitive situation where the producer competes with a firm producing the same product. We employ the market share attraction model to Incorporate the competitive situation and completely characterize the equilibrium by using the Nash equilibrium concept for the game solution. Our results show that the equilibrium depends on the contract terms and the magnitude of the quality related variables. Compared to the non-competitive situation, the probability of producer's Inspection and the probability of supplier's choosing the high quality technology increases in a competitive situation. This is true even when the competitor's quality is lower than the producer's lowest. As a result, the quality of the final product increases In a competitive situation. And as the failure cost borne by the supplier increases, the probability of choosing the high quality technology Increases and the probability of inspection decreases. The net effect of this results in the decrease of the final product quality.