• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.137-140
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• 2007

We consider the optimum air flow channel design for DMFC's in the present study. The effect of pressure drop across the inlet and outlet of a stack on the performance of a DMFC is the optimization of such geometric parameters is crucial to minimize the parasitic power usage by the auxiliary devices such as fuel pumps and blowers. In this paper, we present how the pressure drop control can optimize the driving point of a DMFC stack. Further, we show how the optimal fuel utilization ratio can be achieved, not degrading the performance of DMFC stacks. Overall, we discuss how the flow channel design affects the selection of balance of plant(BOP) components, the design of DMFC systems and the system efficiency.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.183-188
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• 2005

The effect of heat conduction resistance on laminar film condensation of the pure saturated vapor in forced flow over a flat plate has been investigated as boundary layer solutions. A efficient numerical methods for water are proposed for its solution. The momentum and energy balance equations are reduced to a nonlinear system of ordinary differential equations with four parameters: the Prandtl number, Pr, Modified Jacob number, $Ja^{\ast}/Pr$, defined by an overall temperature difference, a property ratio $\sqrt{P_l{\mu}_l/P_v{\mu}_v}$ and the conjugate parameter ${\zeta}$. The similarity and simplified solutions obtained reveal the effects of the conjugate parameter.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.303-311
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• 2005

The problem of conjugate laminar film condensation of the pure saturated vapor in forced flow over a flat plate has been investigated as boundary layer solutions. A simple and efficient numerical method is proposed for its solution. The interfacial temperature is obtained as a root of 3rd order polynomial for laminar film condensation, and it is presented as a function of the conjugate parameter. The momentum and energy balance equations are reduced to a nonlinear system of ordinary differential equations with four parameters: the Prandtl number, Pr, Jacob number, $Ja^{\ast}$, defined by an overall temperature difference, a property ratio R and the conjugate parameter ${\zeta}$. The approximate solutions thus obtained reveal the effects of the conjugate parameter.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.3 s.246
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• pp.238-245
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• 2006

This paper proposes appropriate conjugate parameters and dimensionless temperatures to analysis the conjugate problem of heat conduction in solid wall coupled with laminar film condensation flow adjacent to horizontal flat plate. An efficient methods for some fluids are proposed for its solution. The momentum and energy balance equations are reduced to a nonlinear system of ordinary differential equations with four parameters: the Prandtl number, Pr, Modified Jacob number, $Ja^*/Pr$, defined by an overall temperature difference, a property ratio $\sqrt{\rho_l{\mu}_l/{\rho_v{\mu}_v}$ and the conjugate parameter $\zeta$. The obtained similarity solution reveals the effect of the conjugate parameter, and the results are compared with the simplified solution. The variations of the heat transfer rates as well as the interface temperature and frictions along the plate are shown explicitly.

• Journal of Soil and Groundwater Environment
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• v.24 no.4
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• pp.11-19
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• 2019

This paper examines an assessment method for terminating the post-closure maintenance of a landfill using a simplified landfill gas model. The case study site is the Sudokwon Landfill in Incheon city, which was closed in 2000. The deviations of the results obtained by the regular model and the simplified model were both slightly over 10% from the measured data. Also, the deviation of the simplified model from the regular model has been less than 5% since 2005. Thus, the simplified model could be applied to other landfills that have been closed for at least 5 years. Additionally, the results of the mass balance analysis using the simplified landfill gas model indicated that 39% of the organic carbon was discharged, leading to organic carbon and organic matter content of 7.2 and 17.6%, respectively, in the landfill by the end of 2018.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.199-208
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• 2010

A friction damper installed at a building shows nonlinear behavior since its stick and slip states are occurred repeatedly depending on the amplitude of external loadings to dissipate input energy. Friction damping is existed for the building with a friction damper. In additionally viscous one is inherently included. Therefore, the building installed in such combined damping is quite involved to find the analytical solution. In this study, first, displacement and acceleration characteristics are identified based on the exact solution for a single-degree-freedom building with a friction damper having both friction and viscous damping. Second, in free vibration, the equivalent viscous damping ratio is obtained by the energy dissipation. Third, numerical analysis is carried out to find response configuration with various friction force ratios. Fourth, corresponding equivalent viscous damping ratio is derived with the finding that the response reaches into steady-state for both friction and viscous damped structure. It is deduced using balance of input external energy and output dissipation energy for steady-state response. Finally, the equivalent viscous damping ratios of free or harmonic vibration are verified through nonlinear analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.177-188
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• 1987

A compute program based on the minimization of total Gibbs' free energy and enthalpy balance was developed to calculate the chemical equilibrium composition and adiabatic flame temperature, especially stressed on NO and CO concentration of Heavy oil. Twenty four components of combustion gases which would be produced from the combustion of Heavy oil were chosen and utilized for the products composition analysis of competing combustion reaction. As the results, following conclusions were turned out; (1) Maximum adiabatic flame temperature was found around to be 2900K, when the stoichiometric air ratio was 0.8. (2) Maximum NO quantity in adiabatic process was occurred when supplied air quantity was around 120% of theoretical air requirement. (3) NO and CO quantities were increased with combustion gas temperature at constant stoichiometric air ratio. (4) At constant temperature of combustion gas, NO quantity was increased and Co quantity was decreased with supplied air quantity.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.84-89
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• 2015

The occurrence of algae caused by eutrophication of fresh water is a pollution source to destroy the aquatic environment. When the high voltage electric field is applied in the water, When a high voltage is applied to the electric field in the water, the algae can be broken the balance of cell membranes, and is dead. In this paper, we develop a water quality improvement system for generating an electric field having a higher energy than the zeta potential when a high voltage is applied to 4,000V. To ensure the mobility of the water quality improvement system, we designed the PV generation system using the optimal size technique that is based on the model of power lack ratio. By evaluating the output characteristics of the water quality improvement system, power generation characteristics of the PV generation system, and battery charging characteristics, we can show that the proposed system can be applicable to the water quality improvement system inhibiting the growth rate of the algae in the fresh water.

• Journal of Information Display
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• v.4 no.2
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• pp.19-24
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• 2003

In order to improve the device performances of organic electroluminescent devices (OELDs), the efficiency of carrier injections into the organic layers from electrodes and the balance of injected carrier densities in the emission region are critical factors. Especially, energy barriers, which exist at the interfaces between electrodes and organic layers, interrupt carrier injections, which lead to unbalanced carrier densities. In this study, ${\alpha}-septithiophene$ (${\alpha}$-7T), as a buffer layer, and composite cathode composed of Al and CsF were formed to improve hole and electron injections, respectively. The orientations of ${\alpha}$-7T molecules were adjusted using the simple rubbing method and the mass ratio of CsF was varied from 1 to 10 wt%. Upon investigation of we believe that the 3 wt% mass ratio of CsF and the horizontal orientation of ${\alpha}$-7T molecules are the optimized conditions for achieving better the performance of OELDs. Device with the horizontally oriented 20 nm thick ${\alpha}$-7T layer and composite cathode shows a turn-on voltage of 7V and luminance of 172 cd/$m^2$ at 4 mA/$cm^2$.

• Biomolecules & Therapeutics
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• v.18 no.2
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• pp.152-158
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• 2010

Melanin concentrating hormone is a neuropeptide highly expressed in the brain that regulates several physiological functions mediated by receptors in the G-protein coupled receptor family, especially plays an important role in the complex regulation of energy balance and body weight mediated by the melanin concentrating hormone receptor subtype 1 (MCH1). Compelling pharmacological evidence implicating MCH1 signaling in the regulation of food intake and energy expenditure has generated a great deal of interest by pharmaceutical companies as MCH1 antagonists may have potential therapeutic benefit in the treatment of obesity and metabolic syndrome. Although fluorescence-based calcium mobilization assay platform has been one of the most widely accepted tools for receptor research and drug discovery, fluorescence interference and shallow assay window limit their application in high throughput screening and have led to a growing interest in alternative, luminescence-based technologies. Herein, a luminescence-based functional assay system for the MCH1 receptor was developed and validated with the mitochondrial targeted aequorin. Aequorin based functional assay system for MCH1 presented excellent Z' factor (0.8983) and high signal-to-noise ratio (141.9). The nonpeptide MCH1 receptor antagonist, SNAP 7941 and GSK 803430, exhibited $IC_{50}$ values of 0.62 ${\pm}$ 0.11 and 12.29 ${\pm}$ 2.31 nM with excellent correlation coefficient. These results suggest that the aequorin based assay system for MCH1 is a strong alternative to the traditional GPCR related tools such as radioligand binding experiments and fluorescence functional determinations for the compound screening and receptor research.