• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.15-20
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• 1996

We present the result of physical studies for three integral-type burnable absorbers of gadolinia, erbia and IFBA, in the hexagonal fuel assembly. The analysis of nuclear characteristics for gadolinia and IFBA cases shows that the spectrum hardening of hexagonal fuel assembly compared to rectangular one leads to smaller reactivity hold-down worth(RHW) and less change of MTC in the negative direction per insertion of one burnable absorber rod. Erbia case, on the other hand, exhibits reversed trend in RHW and MTC due to the enhanced absorption of large resonance of Erbium at 0.5 eV It turns out to be that Erbia performs best in terms of minimizing the peak pin power and maintaining as more negative MTC as practically attainable during the entire operational phase, and IFBA provides the least residual reactivity penalty at EOC. Therefore, we take Erbium as the suitable burnable absorber and provide optimal designs of 60, 120, 180, 240 and 300 erbia-shimmed hexagonal fuel assemblies with regard to minimizing the peak pin power.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.369-371
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• 2006

Conventional active-clamp forward converter has narrow ZVS range of main switch. Although utilizing high magnetizing current can realize wide ZVS range, it increases the conduction loss. To solve this problem, a new asymmetric two-transformer active clamp forward converter is proposed. Proposed converter achieves wide ZVS range without severe conduction loss penalty, which results in high efficiency and high power density.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.7
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• pp.339-344
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• 2000

This paper presents an improved optimal power flow algorithm, which solves an optimization problem with equality constraints with converted inequality constraints. The standard OPF and the penalty function method should do reconstructing active constraints among the inequality constraints so that the activation of the inequality constraints has been imposing an additional burden to solve OPF problem efficiently. However the proposed algorithm converts active inequality constraints into the equality constraints in order to preclude us from reconstructing the procedures. The effectiveness of the new OPF algorithm is validated by applying the IEEE 14 bus system.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.297-299
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• 1999

The B-coefficient method is well-known and universally used method for its simplicity and computation speed. However, the B-coefficient method has a weak point of accuracy when it is applied to the ill-conditioned systems where generators produce excessive reactive power. This paper describes the developed module to be applied to commercial program package of calculating the penalty factors by Jacobian method. The effectiveness of the proposed program has been demonstrated using the IEEE 30 bus system.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.581-583
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• 1995

This paper presents a theory on the pricing and allocation of spinning reserve. It is shown in this paper, that it is possible to maintain system security with many participants each attempting to optimize their own benefit, through pricing incentive. Participant offers power consumption/generation and reserve contribution according to its price. And Price setter only distribute pricing signal to acquire system security. Participants induce disturbance on power system and they pay the penalty according to the size of disturbance. And they also offers some reserve capacity to earn reserve cost. In this scheme, the amount of data communication is very small.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3125-3130
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• 2008

Coal is one of the most abundant and cheapest energy sources in the earth, but its typical combustion product, $CO_2$, is related with serious recent environmental issues such as global warming. The Integrated Coal Gasification Combined Cycle (IGCC) with $CO_2$ sequestration is one of the most promising options to produce electricity using a relatively cheap fuel (coal) with minimum impact on environment. In IGCC power generation systems, some chemical reactions are required to gasify coal to produce syngases such as $H_2$ and CO, which would be burnt in the combustor to produce heat for power generation, with a penalty of additional energy consumption. In this paper, several chemical reactions for the gasification of coal are considered and their characteristics are investigated.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.6
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• pp.220-229
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• 1985

This paper proposes a new optimal unit commitment algorithm for the rational operation of electric power systems. Especially, the algorithm is improved by considering transmission line capacity limits and load forecasting uncertainty with the consideration of the participation factors of each units, so that the method becomes more reliable and flexible one. The transmission losses are considered by using updated penalty factors obtained from the constant matrixes of the fast decoupled load flow method, the system loads are distributed at each buses, and the several necessary operational constraints are also considered for the purpose of presenting a more practicable scheme. Finally, the effectiveness of the proposed algorithm has been demonstrated by applying to the 23-bus model system.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.38-42
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• 2006

Pressure drops and friction factors in square channels with twisted tape inserts plus axial interrupted ribs are investigated. Tests are performed for Reynolds numbers ranging from 8,900 to 29,000. The rib height-to-channel hydraulic diameter, $e/D_h$, is kept at 0.057 and test section length-to-hydraulic diameter, $L/D_h$ is 30. The pressure drops and friction factor values are enhanced with axial interrupted ribs and twisted tape inserts. Square channels with twisted tape inserts plus axial interrupted ribs show the greatest pressure loss penalty in the present work. Friction factor data obtained for the square channel with twisted tape inserts plus axial interrupted ribs are less than those in the past publications for circular tubes with axial interrupted ribs and twisted tape inserts.

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.3
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• pp.567-571
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• 2012

To design the long-haul optical communication system, we need to decide the type of optical fiber and optical amplifier, span length of optical amplifier, dispersion compensation method, optical signal power, etc. Therefore, we need to predict the performance of optical communication system when we change one of the system parameters. In this paper, we investigate the method of predicting the maximum transmission length of the designed optical communication system and finding the optimum optical signal power to obtain the maximum transmission length.