• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.261-266
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• 2003

An experimental study has been conducted to evaluate the effects of $CO_{2}$ on heat transfer from hydrogen oxygen-enriched flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which mounted on top of the furnace. Five composition conditions of oxidizer were chosen with replacing $N_{2}$ with $CO_{2}$. In a steady state, total and radiative heat flux rates from the flame to the wall of furnace has been measured using heat flux meters. Temperature distribution in furnace also has been checked. Increasing $CO_{2}$ ratio in the oxidizer, the dominant heat transfer mode was changed into convection from radiation. Temperature in the furnace decreased but total heat flux increased.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1959-1963
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• 2007

SMES systems need cryogenic cooling systems. Conduction cooling system has more effective, compact structure than cryogen. In general, 2 stage GM cryocoolers are used for conduction cooling of HTS SMES system. 1st stages of cryocoolers are used for the cooling of current leads and radiation shields, and 2nd stages of cryocoolers for HTS coil. For the effective conduction cooling of the HTS SMES system, the temperature difference between the cryocooler and HTS coil should be minimized. In this paper, a cryogenic conduction cooling system for HTS SMES is analyzed to evaluate the performance of the cooling system. The analysis is carried out for the steady state with the heat generation of the HTS coil and effects of the thermal contact resistance. The results show the effects of the heat generation and thermal contact resistance on the temperature distribution.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.990-994
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• 2004

This paper presents a method to predict the transient characteristic of the air lubricated slider head in a hard disk drive by using optimization technique. The time dependent modified Reynolds equation based on the molecular slip flow approximation equations was used to describe the fluid flow within the air bearing and the implicit finite difference scheme is applied to calculate the pressure distribution under the slider head. The exhaustive search combined with the Broyden-Fletcher-Goldfarb-Shanno method were employed to obtain optimum design variables which are taper angle, rail width and taper length in order to keep the forces and moments acting on the slider head in dynamic equilibrium. The results show that the optimal head slider of the magnetic head has good stability characteristic that can reach the steady state within 0.5 microsecond.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.1
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• pp.57-64
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• 1984

Forward extrusion of sintered porous metal through conical converging die is analyzed using slab method on the basis of plasticity theory for porous metal. It is taken into consideration in the analysis that the material in the container is continuously recompressed on densified until the process reaches steady state. Extrusion pressure and distribution of relative density from the die inlet to the outlet are calculated under various process variables. The results are useful in finding initial relative density of the billet, reduction of area and cone angle of the die in order to get required final products. Experiments are done for porous copper and then compared with the computed results.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.36-41
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• 1993

The adiabatic slirn-type autoclave reactor for free radical polymerization of LDPE is represented by a two-compartment four-cell model, which is proven effective to predict the reactor behavior as well as the polymer properties. Since the temperature distribution along the reactor axis plays the central role for the properties of the polymer product, it is important in practice to regulate the temperature in each compartment. The present study aims for the application of the adaptive control algorithm not only in the period of start-up but also during the steady state operation. It is shown that the temperature control is significantly improved over the conventional PID-control and this also brings about a reduction of variations in the polymer properties. This study demonstrates the potential application of the adaptive controller for the control of the polymerization reactor operated under the adiabatic condition.

• Journal of the Korean Data and Information Science Society
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• v.20 no.6
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• pp.973-982
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• 2009

Two losing games that can be combined, either by periodic alternation or by random mixture, to form a winning game are known as Parrondo games. We consider a collective version of Parrondo games in which players are allowed to choose the game to be played by the whole ensemble in each turn. In this paper, we analyze the long-range optimization strategy for all choices of the parameters and find the expected average profit in the steady state.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.937-944
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• 2004

An experimental study has been conducted to evaluate the effects of $CO_2$ on heat transfer from oxygen-enriched hydrogen flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which was mounted on top of the furnace. Five different oxidizer compositions were prepared by replacing $N_2$ with $CO_2$. In a steady state, the total as well as radiative heat flux from the flame to the wall of furnace have been measured using a heat flux meter. Temperature distribution in furnace also has been measured and compared. By increasing $CO_2$ proportion in the oxidizer, the convection played a more significant role rather than radiation. Overall temperature in the furnace was seen to be decreased, while the total heat flux has increased.

• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.519-530
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• 2001

A two commodity continuous review inventory system with independent Poisson processes for the demands is considered in this paper. The maximum inventory level for the i-th commodity fixed as $S_i$(i = 1,2). The net inventory level at time t for the i-th commodity is denoted by $I_i(t),\;i\;=\;1,2$. If the total net inventory level $I(t)\;=\;I_1(t)+I_2(t)$ drops to a prefixed level s $[{\leq}\;\frac{({S_1}-2}{2}\;or\;\frac{({S_2}-2}{2}]$, an order will be placed for $(S_{i}-s)$ units of i-th commodity(i=1,2). The probability distribution for inventory level and mean reorders and shortage rates in the steady state are computed. Numerical illustrations of the results are also provided.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.788-789
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• 2011

A comprehensive thermo-electromagnetic model has been developed to estimate temperature and electromagnetic distribution in an three-phase induction motor under steady state operation. Electromagnetic modeling enables us to predict thermal dissipation rates by eddy-current loss and copper loss in induction motors. Non-uniform temperature distributions are investigated to account for the strong effect of local temperature build-up on the motor performance and expected life-span. For more accurate thermal modeling purpose, Heat loss mapping method, which is matched up with electromagnetic losses and volumetric heat source, is developed and performed analysis. Heat loss mapping method can be greatly used as a design or diagnostic tool for three-phase induction motors with complex structural electromagnetic fields.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1330-1331
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• 2011

The on-grid distributed power system operated antiislanding due to the momently voltage sag of the power system, fault and etc. According to the 'Dispersed Generations in Distribution Systems Connection Technology Standard', the utilizable time ratio of PCS is low because of being put into in the steady state of the power system after 5 minutes. In this paper, the output characteristic is optimized with the hybrid system consisting of the wind system and PV system. And energy of hybrid system is supplied to the power system. Also, DVR function was applied to PCS to compensate the voltage sag frequently happening for a power system. The control performance of the proposed hybrid PCS is analyzed and simulated using PSIM to validate the system performace.