• Proceedings of the KSR Conference
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• 2005.11a
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• pp.823-829
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• 2005

The extent of slack is correlative with the wheelbase of vehicle as well as the distance between the inner faces of flanges. Since the movable clearance of wheel flange is getting reduced in curved track, the vehicle is more difficult to negotiate the track. By this reason, a certain extent of slack is normally designed for curved track to allow the movable clearance corresponding to that of straight track. In case of some foreign railways,. the fixed extent of slack has been classified by the ranges of curve radius. In case of KNR, the slack is calculated by a formula for each case of curve radius and it therefore seems quite precise method. However, since there is a wide range of slack adjustment $(S'=0\~15mm)$ in calculation formula itself, too excessive or too little slack can be calculated. This study is to approach the technical review on slack calculation and to offer the reasonable slack design through the full-scale experiment at sharp curved track without slack.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.49-51
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• 2000

ln this paper, a method by which penalty factors of all generators including slack bus can be directly derived is presented. With a simple re-assignment of angle reference bus to a bus where no generation exists, penalty factors for slack bus is obtained without any physical assumption. While previous Jacobian-based techniques for generator penalty factor calculation have been derived with basis upon reference bus, proposed method are not dependent on reference bus and calculated penalty factors can be substituted directly into the general ELD equation to compute the economic dispatch. Equations for system loss sensitivity, penalty factors and optimal generation allocation are solved simultaneously in normal power flow computation.

• The Transactions of the Korea Information Processing Society
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• v.7 no.7
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• pp.2229-2237
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• 2000

This paper intends to improve the problems of the slack stealing algorithm scheduling for periodic tasks with fixed priority and aperiodic tasks which occur dynamically. The Slack stealing algorithm reduces unnecessary waiting time by making the service possible immediately when the slack stealing server gives suitable priority to aperiodic tasks according to the status of aperiodic tasks arrivals at runtime. But no performs the slack stealing, we must calculate execution time of periodic tasks till the point of random. And, execution time of periodic tasks is being repeatedly every hours while the slack algorithm is applied. We show time complexity hen is used as to O(n) if the nubmer of tasks which is applied to the calculation is n. In this appear, due to stored in tables slack times and the execution times of the scheduled periodic tasks, the complexity of aperiodic tasks which is occurring dynamically reduced to O(log n) and improves the responses times. We prove the algorithm proposed in this paper through the simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.73-82
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• 2001

In this Paper, slack is computed from a comparision of the cable pay out rate and the ship ground speed in accordance with laying conditions, and the speed controller of the cable engine based on an $H^{\infty}$ servo control is designed for adjusting the cable engine in order to lay a desired amount of slack. The controller is designed to have the robust tracking property of the cable engine under disturbances. The performance of the designed controller is evaluated by computer simulation, and, consequently, a feasibility study for laying the submarine cable stably is done through analyzing simulation results.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.1
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• pp.1-5
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• 2001

In this paper, a new method for calculating the penalty factors of all generators including the slack bus is presented. A simple transposition of the angle reference, from the conventional slack bus to another bus where no generation exists, enables the derivation of the loss sensitivity of the slack bus. Penalty factors are obtained without any physical assumption through a simple substitution of the bus loss sensitivities. Penalty factors calculated by proposed method are not dependent on reference bus and can also be directly substituted into the general ELD equation for computing the optimal dispatch. Equations for loss sensitivities, Penalty factors and ELD are calculated simultaneously in normal power flow computation. A case study on a test system has proved the effectiveness of the proposed' angle reference transposition' method.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.205-210
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• 1992

The power flow calculations are the most important and powerful tools in the various studies of power system engineering. Newton-Raphson method, among the various power flow calculation techniques, is normally used due to its rapidness of numerical convergency. In the conventional Newton-Raphson method, however, there are some unrealistic assumptions, in which all the system power losses are considered to be supplied by the slack bus generator. Introducing the system power loss formula and augmenting the conventional Newton-Raphson power flow method, we can relieve the unrealistic assumption and improve the performance of power flow calculation. In this study, A new approach for handling the losses and augmenting the conventional power flow problem is proposed. The proposed method estimates the increamental changes of active power on each generation bus with respect to the change of total system power losses and the estimated value are used to update the slack bus power. If some studies for more theoritical investigations and verifications are followed, the proposed approach will show some improvement of the conventional method and give lots of contribution to increase the performance of power flow techniques in power systems engineering.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4102-4111
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• 2023

In order to better perform thermal hydraulic calculation and analysis of supercritical water reactor, based on the experimental data of supercritical water, the model training and predictive analysis of the heat transfer coefficient of supercritical water were carried out by using the support vector machine (SVM) algorithm. The changes in the prediction accuracy of the supercritical water heat transfer coefficient are analyzed by the changes of the regularization penalty parameter C, the slack variable epsilon and the Gaussian kernel function parameter gamma. The predicted value of the SVM model obtained after parameter optimization and the actual experimental test data are analyzed for data verification. The research results show that: the normalization of the data has a great influence on the prediction results. The slack variable has a relatively small influence on the accuracy change range of the predicted heat transfer coefficient. The change of gamma has the greatest impact on the accuracy of the heat transfer coefficient. Compared with the calculation results of traditional empirical formula methods, the trained algorithm model using SVM has smaller average error and standard deviations. Using the SVM trained algorithm model, the heat transfer coefficient of supercritical water can be effectively predicted and analyzed.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.528-530
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• 1995

In the conventional power flow calculations, the slack bus is assumed to undertake the total transmission loss for the convenience of numerical computation. This is an unrealistic assumption because, in real power system, the transmission loss is supplied by all the generators and makes the power flow calculation results somewhat distorted. This paper proposes a new loss redistribution algorithm that can reduce the distortion of power flow results. In the proposed method, the system power loss redistribution algorithm is added to the conventional power flow equations and jacobian elements that are related the real power are newly constructed. In each iteration step, the power output of each generator is updated to consider the effect of calculated total power losses. Finally the usefulness of proposed method are tested through the some appropriate case studies.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.65-72
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• 1998

This paper presents a fast calculation method for evaluating of voltage stability margin (MW) using the line flow equation in polar form. Here, Line flow equations $(P_{ij},\;Q_{ij}$ are comprised of state variable, $V_i,\;{\Delta}_i,\;V_j$ and ${Delta}_j$, and line parameter, r and x. using the feature of polar coordinate, these becomes one equation with two variables, $V_j,;V_j$. Moreover, if bus j is slack or generator bus, which is specified voltage magnitude in load flow calculation, it becomes one equation with one variable $V_ i $ that is, may be formulated with the second-order equation for $V^2_i$. Therefore, multiple load flow solutions may be obtained with simple computation. The obtained load flow multiple solutions are used for evaluating of voltage stability through sensitivity analysis or its closeness. Also, the method is proposed to calculate for voltage stability margin considering shunt capacitor, which is important element for evaluating of voltage stability. The proposed method was validated to sample systems.

• Structural Engineering and Mechanics
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• v.16 no.3
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• pp.317-326
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• 2003

The tension leg platform (TLP) is a moored floating offshore structure whose buoyancy is more than its weight. The mooring system, known as tethers, is vulnerable to failure due to extreme (maximum and minimum) tensions. In the present study the reliability of these tethers under maximum and minimum tension (ultimate limit state) has been studied. Von-Mises failure criteria has been adopted to define the failure of a tether against maximum tension. The minimum tension failure criteria has been assumed to meet when the tethers slack due to loss of tension. First Order Reliability method (FORM) has been adopted for reliability assessment. The reliability, in terms of reliability index, and probability of failure has been obtained for twelve sea states. The probabilities of failure so obtained for different sea states have been adopted for the calculation of annual and life time probabilities of failure.