• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.67-74
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• 2009

This paper describes the speed control functions of the typical steam turbine speed controllers and the test results of generator load rejection simulations. The goal of the test is to verify the speed controller's ability to limit the steam turbine's peak speed within a predetermined level in the event of generator load loss. During normal operations, the balance between the driving force of the steam turbine and the braking force of the generator load is maintained and the speed of the turbine-generator is constant. Upon the generator's load loss, in other word, the load rejection, the turbine speed would rapidly increase up to the peak speed at a fast acceleration rate. It is required that the speed controller has the ability to limit the peak speed below the overspeed trip point, which is typically 110[%] of rated speed. If an actual load rejection occurs, a substantial amount of stresses will be applied to the turbine as well as other equipments, In order to avoid this unwanted situation, not an actual test but the other method is necessary. We are currently developing the turbine control system for another nuclear power plant and have plan to do the simulation suggested in this paper.

• Computational Structural Engineering
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• v.8 no.1
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• pp.123-126
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• 1995

The purpose of the analysis is the numerical simulation of structures strained to the limit loads. The finite element calculations and experiments with cracked structures have been carried out yielding over limit strains between 10% and 15% by single peak load. Load versus displacement-diagrams and J-diagrams up to the limit load are calculated. By this way the influence of geometric parameters may be assessed in the post yield region. It is proposed to use such calculations to correlate experiments carried out with small specimens to experiments simulating the true dimensions of the design structure.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.5
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• pp.376-383
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• 2022

The improved performance of computer parts, such as graphic card, CPU, and main board, has led to the need for power supplies with a high power output. The dynamic load profile rapidly changes the usage of power consumption depending on load operations, such as PC power and air conditioner. Under dynamic load profile conditions, power consumption can be classified into maximum, normal, and standby power. Several problems arise in the case of maximum power. Peak power is generated at the system power source in the maximum-power situation. Frequent generation of peak power can cause high-frequency problems and reduce the life of high-pressure parts (especially high-pressure capacitors). For example, when a plurality of PCs are used, system overload occurs due to peak power generation and causes problems, such as power failure and increase in electricity bills due to exceeded contract power. To solve this problem, a system peak power limit/compensation power circuit is proposed for a power supply under dynamic load profile conditions. The proposed circuit detects the system current to determine the power situation of the load. When the system current is higher than the set level, the circuit recognizes that the system current generates peak power and compensates for the load power through a converter using a super capacitor as the power source. Thus, the peak power of loads with a dynamic load profile is limited and compensated for, and problems, such as high-frequency issues, are solved. In addition, the life of high-pressure parts is increased.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.21-28
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• 2013

The paper proposes an optimal sizing method of a customer's battery energy storage system (BESS) which aims at managing the electricity demand of the customer to minimize electricity cost under the time of use(TOU) pricing. Peak load limit of the customer and charging and discharging schedules of the BESS are optimized on annual basis to minimize annual electricity cost, which consists of peak load related basic cost and actual usage cost. The optimal scheduling is used to assess the maximum cost savings for all sets of candidate capacities of BESS. An optimal size of BESS is determined from the cost saving curves via capacity of BESS. Case study uses real data from an apartment-type factory customer and shows how the proposed method can be employed to optimally design the size of BESS for customer demand management.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1499-1502
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• 2003

This paper describes the result of carbody and vibration test for freight car. The purpose of the test is to evaluate an safety which carbody structure shall be considered fully sufficient rigidity so as to load a freight car under maximum load and operating condition on line track. The test carbody is constructed by RS korea co., LTD. in accordance with KNR specfication. The test cases of the carbody is tested the vertical load and compressive load to verify the strength and stillness. The vibration test is tested for analysis and evaluation of vibration, to allow for the fact that mechanical vibration in railway vehicles have specific characteristics.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.276-278
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• 1999

In this paper, we analyze customers' working electric energy (kWh) which is served pole-transformer in order to reduce peak load current error which is generated in application load correlation equation. The characteristic of electric load which customers are using is classified by customer's working electric energy (kWh) and ratio of cooling equipment possession. For the input data of fuzzy model, we used to kWh on April which represents basic load and kWh which is increased from April to August. The April kWh is used to classify into large, medium, small customer. Also, the increased kWh is used to know information of cooling equipment possession. For the output value of fuzzy model, we can determined peak load current limit in application load correlation equation.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.852-858
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• 2012

This paper describes evaluation results of the wind power penetration limit (WPPL) and the wind energy penetration (WEP) in the Mongolian central power system (MCPS). A wind power plant (WPP) in a power system possesses an output power limit because the power system must maintain a balance between the generation and consumption of electricity at all times in order to achieve an adequate level of quality. The instantaneous penetration limit (IPL) of wind generation at a load is determined as the minimum of the three technical constraints: the minimum output, the ramp rate capability, and the spinning reserve of the conventional generating units. In this paper, a WPPL is defined as the maximum IPL divided by the peak load. A maximal variation rate (VR) of wind power is a major factor in determining the IPL, WPPL, and WEP. This paper analyzes the effects of the maximal VR of wind power on the WPPL, WEP, and capacity factor (CF) in the MCPS. The results indicate that a small VR can facilitate a large amount of wind energy while maintaining a high CF with increased wind power penetration.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2223-2233
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• 1993

An engineering method is suggested to calculate the applied load versus crack extension in the elastic-plastic fracture. The condition for an increment of crack extension is set by a critical increment of crack-up opening displacement(CTOD). The ratio of the CTOD increment to the incremental crack extention is a critical crack-tip opening angle(CTOA), assumed to be constant for a material of a given thickness. The Dugdale model of crack-tip deformation in an infinite plate is applied to the method, and a complete solution for crack extension and crack instability is obtained. For finite-size specimens of arbitrary geometry in general yielding, an approximate generalization of the Dugdale model is suggested so that the approximation approaches the small-scale yielding solution in a low applied load and the finite-element solution in a large applied load. Maximum load is calculated so that an applied load attains either a limit load on an unbroken ligament or a peak load during crack extension. The proposed method was applied to three-point bend specimens of a carbon steel SM45C in various sizes. Reasonable agreements are found between calculated maximum loads and experimental failure loads. Therefore, the method can be a viable alternative to the J-R curve approach in the elastic-plastic fracture analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.12
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• pp.715-726
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• 1999

This paper estimates the capacity of shunt type active power filters(APF) for harmonic/reactive power compensation with a thyristor converter load. The base capacity requirement of APF is defined for idealized converter load current waveform and the effect of commutation overlap on the APF capacity is examined. The APF capacity required for reactive power compensation in addition to the harmonic elimination is estimated to give maximum achievable power factor for various operating condition of the partially-loaded thyristor converter. The method of current limit of APF is introduced, and it is shown that the APF capacity can be considerably reduced by deliberately limiting the peak current while maintaining the filtering performance to meet the level std 519 regulation.

• Structural Engineering and Mechanics
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• v.19 no.1
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• pp.1-20
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• 2005

The expertise required in the judicious use of nonlinear finite element (FE) packages for design-assistance purposes is not widely available to the average engineer, whose sole aim may be to obtain an estimate for a single design parameter, such as the limit load capacity of a structure. Such a parameter may be required for the design of a proposed reinforced concrete (RC) floor slab or bridge deck with a given set of geometrical and material details. This paper outlines a procedure for developing design-assistance equations for carrying out such predictions for partially restrained RC slabs under uniformly distributed loading condition, based on a database of FE results previously generated from a large number of 'numerical model' slabs. The developed equations have been used for predicting the peak loads of a number of experimental RC slabs having varying degrees of edge restraints; with results showing a reasonable degree of accuracy and low level of scatter. The simplicity of the equations makes them attractive and their successful use in the field of application reported in this paper suggest that the outlined procedure may also be extended to other classes of concrete structures.