• 한국유체기계학회 논문집
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• 제14권6호
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• pp.68-75
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• 2011

This study simulated the effect of steam injection on the performance and operation of a gas turbine combined heat and power (CHP) system. A commercial simple cycle gas turbine was analyzed. A full off-design analysis was carried out to investigate the variations in not only engine performance but also the operating characteristics of the compressor caused by steam injection. Variation in engine performance and operation characteristics according to various operation modes were examined. First, the impact of full steam injection was investigated. Then, operations aiming to guarantee a minimum compressor surge margin, such as under-firing and partial steam injection, were investigated. The former and latter were turned out to be relatively superior to each other in terms of power and efficiency, respectively.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.879-884
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• 1995

The results of performance assessment analyses have shown that the long-lived radionuclides such as I-129 control the potential individual dose impact to the public. I-129 is difficult-to-measure(DTM) in low-level waste because it is non-gamma emitting radionuclides and exists at extremely low concentrations in radioactive waste generated by nuclear reactors. In this study, computer modeling technique to predict release rate of I-129 is developed to provide another tools far performance assessment of land disposal facilities and characteristics of radwaste. Model suggested in this study will give conservative values of I-129 release rate far determination of radwaste characteristics. More detailed approach is implemented to account for release conditions of fuel source-nuclides. 1-131 concentration measured from reactor coolant and released fraction from tramp fuel have dominant roles in calculating release rate of I-129 with fuel defect conditions.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1650-1657
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• 2019

Fluidelastic instability and nonlinear dynamics of tube bundles is a key issue in a steam generator. Especially, once the post-instability motion of the tube becomes larger than the clearance gap to other tubes, effective contact or impact between the tubes under consideration and the other tube inevitable. There is seldom theoretical analysis to the nonlinear dynamic characteristics of a tube array in two-phase flow. In this paper, experimental and numerical studies were utilized to obtain the critical velocity of the flow-induced instability of a rotated triangular tube array. The calculation results agreed well with the experimental data. To explore the post-instability dynamics of the tube array system, a Runge-Kutta scheme was used to solve the nonlinear governing equations of tube motion. The numerical results indicated that, when the flow pitch velocity is larger than the critical velocity, the tube array system is undergoing a limit cycle motion, and the dynamic characteristics of the tube array are almost similar for different void fractions.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1686-1704
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• 2021

This study addresses the numerical simulation of the shield building of an AP1000 nuclear power plant (NPP) subjected to a large commercial aircraft impact. First, a simplified finite element model (F.E. model) of the large commercial Boeing 737 MAX 8 aircraft is established. The F.E. model of the AP1000 shield building is constructed, which is a reasonably simplified reinforced concrete structure. The effectiveness of both F.E. models is verified by the classical Riera method and the impact test of a 1/7.5 scaled GE-J79 engine model. Then, based on the verified F.E. models, the entire impact process of the aircraft on the shield building is simulated by the missile-target interaction method (coupled method) and by the ANSYS/LS-DYNA software, which is at different initial impact velocities and impact heights. Finally, the laws and characteristics of the aircraft impact force, residual velocity, kinetic energy, concrete damage, axial reinforcement stress, and perforated size are analyzed in detail. The results show that all of them increase with the addition to the initial impact velocity. The first four are not very sensitive to the impact height. The engine impact mainly contributes to the peak impact force, and the peak impact force is six times higher than that in the first stage. With increasing initial impact velocity, the maximum aircraft impact force rises linearly. The range of the tension and pressure of the reinforcement axial stress changes with the impact height. The perforated size increases with increasing impact height. The radial perforation area is almost insensitive to the initial impact velocity and impact height. The research of this study can provide help for engineers in designing AP1000 shield buildings.

• 국토계획
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• 제54권4호
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• pp.122-130
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• 2019

The purpose of this study is to analyze effect of climate and urban factors on energy resilience, and to explore policy alternatives to strengthen resilience of energy system. For this purpose, this study used extensive literature review on resilience studies and multiple regression analysis. In this study, blackout time was set as a dependent variable. And the independent variables were divided into climate and urban (robustness, countermeasure capacity) characteristics. As a result of the analysis, in terms of climate characteristics, maximum wind speed and cooling/heating degree-day have statistically significant impact on blackout time. With regard to urban characteristics, number of consumer, ratio of deteriorated housing and coast dummy variables have statistically significant impact on blackout time. And the ratio of government employees and road ratio were found to be the most influencing factors to shorten time taken to restore original level of electricity supply. Based on the study results, several policy suggestions to improve energy resilience were made such as continuous management of vulnerable areas and strengthening disaster response services. This study only considered engineering dimension of resilience. Further studies need to be approached on ecological & social-ecological dimension.

• 설비공학논문집
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• 제22권8호
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• pp.562-566
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• 2010

Wind energy is one of the most general natural resources in the world. However, as of today, generating electricity out of wind energy is only available from big wind generator, Furthermore, an axial-flow turbine is the only way to produce electricity in the big wind generator. This paper is for the guidance of drawing impact fact about power turbine using cross-flow type transferring wind energy to electricity energy. It will find the ideal value which enables to make cross-flow power turbine(CPT) using computational fluid dynamics(CFD) code. This study tries to analyze the "Solidity" characteristics. We can find out turbine-blade number through CFD. CFD is using "Fluent_ver 6.3.16", and the data from its result will judge fan-blade performance through specific torque and specific power from each "Solidity" model. Based upon the above, we will make cross-flow power turbine of multi-blade centrifugal fan instead of axial-flow type.

• International Journal of Control, Automation, and Systems
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• 제3권spc2호
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• pp.355-362
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• 2005

Deregulations and market practices in power industry have brought great challenges to the system planning area. In particular, they introduce a variety of uncertainties to system planning. New techniques are required to cope with such uncertainties. As a promising approach, probabilistic methods are attracting more and more attentions by system planners. In small signal stability analysis, generation control parameters play an important role in determining the stability margin. The objective of this paper is to investigate power system state matrix sensitivity characteristics with respect to system parameter uncertainties with analytical and numerical approaches and to identify those parameters have great impact on system eigenvalues, therefore, the system stability properties. Those identified parameter variations need to be investigated with priority. The results can be used to help Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs) perform planning studies under the open access environment.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.55-64
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• 2016

The development of high-speed rail (HSR) has had a major impact on the power supply grid. Based on the monitored waveforms of HSR, a pattern recognition approach is proposed for the first time in this paper to identify the operating conditions. To reduce the data dimensions for monitored waveforms, the principal component analysis (PCA) algorithm was used to extract the characteristics and their waveforms from the monitored waveforms data. The dynamic time wrapping (DTW) algorithm was then used to identify the operating conditions of the HSR. Cases studies show that the proposed approach is effective and feasible, and that it is possible to identify the real-time operating conditions based on the monitored waveforms.

• 유공압시스템학회논문집
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• 제7권1호
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• pp.11-19
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• 2010

A gas-assisted hydraulic breaker uses both hydraulic and pneumatic energies and the appropriate balance between them mostly effects its performance. Mathematical modeling of the breaker is established and verified by experiment. Through sensitivity analysis using AMESim, the key design parameters are selected, which mostly affect the performance of the breaker. Taguchi method is used to optimize the key design parameters to maximize the output power for long and short strokes through simulation. As the result, the output power as well as the impact energy are increased significantly compared with the existing design. The pressure pulsation in the supply line is reduced to a tolerable level and the dynamic characteristics of the piston displacement is also improved by the optimization.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.547-549
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• 2000

Silicone insulators have many advantages over porcelain insulators. Especially silicone insulators have good characteristics of impact hardness, surface insulation, ease of processing, mass productivity and don't have risk of bombardment and vandalism. Recently insulation part made by silicone are becoming widely used. In this paper we introduce the development of Sealing End for 132kV XLPE cable with silicone composite hollow insulator and the adoption of it to a actual transmission line in abroad. This paper contains of design procedure, structure, electrical performance of it.