• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.98-101
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• 1988

A non load level decomposition algorithm is presented for power system reactive source planning. The fuel cost is introduced to performance index in optimal operation problem. The investment variables are all reactive sources such as capacitance or inductance. Experiment showed a desirable result and the computation time reduced considerably.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.211-212
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• 2006

• Ocean and Polar Research
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• v.23 no.2
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• pp.173-179
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• 2001

Parallel supercomputing is now a must for oceanographic numerical modelers. Most of today's parallel numerical schemes use synchronous algorithms, where some processors that have finished their tasks earlier than others must wait at synchronization points for correct computation. Hence, the load balancing is a crucial factor, however, it is, in general, difficult to achieve on heterogeneous workstation clusters. We devise an asynchronous algorithm that reduces the idle times of faster processors, and discuss application of the algorithm to some grid problems and implementation on a workstation cluster using Message Passing Interface (MPI).

• Journal of Drive and Control
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• v.12 no.1
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• pp.15-20
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• 2015

For testing a newly designed ship's steering gear, a steering gear test bench with a steering gear to be tested and a load generation part should be prepared. The load given to the steering gear has to be pertinent to the load generated in a targeted ship. In this study, the authors suggest a process of estimating the load given to steering gears in ships. At first, a test for measuring the load in the steering gear of a real ship was conducted. Then, a process was developed to compute rudder driving torque and force by using basic equations including some empirical equations on ship's steering. The test results and the computation results on the load in the steering gear were compared, As a result, the process suggested in this study for estimating load in ship's steering gears was verified.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.2
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• pp.140-147
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• 1998

Since a structure carries out its given functions and purposes while it is always resisting against the external load, the capacity of the resistance in the structure within the range that will not collapse the structure itself becomes the important factor in the design of the structures. Therefore, many suggestions were proposed and noted for determining method of the collapse load. Some of the methods from the suggestions have been commonly used due to the considerations on their distinctive advantages such as the compactness of the conceptions and the convenience in the computation. However, in case when the variation becomes huge in the materials and load, the results would carry(have or contain) many uncertain elements. On the other hand, load incremental method which regards the characteristics of the probability must be more attainable method even though it might complicate the calculation. This study intends to develop a finite element model that uses the probabilistic load incremental method to estimate the collapse load, and also to compare the result of the analysis with the linear load incremental method and Turkstra's Rule.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.421-427
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• 2005

This work analyzes the behaviors of aerated lubricant in the gap between con-rod bearing and journal. It is assumed that the film formation with aerated lubricant is influenced by the two major factors. One is the density characteristics of the lubricant due to the volume change of lubricant for the formation of bubbles and the other is the viscosity characteristics of the lubricant due to the surface tension of the bubble in the lubricant. These two major factors surprisingly increase the load capacity in some ranges of bubble sizes and densities. Modified Reynolds' equation is developed for the computation of fluid film pressure with the effects of aeration ratio in the lubricant. From the calculated load capacity by solving modified Reynolds' equation, journal locus is computed with Mobility method after comparing it with the applied load at each time step. The differences of journal orbits between aerated and pure lubricants are shown in the computed results.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.2
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• pp.121-128
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• 2004

This paper presents a new approach for determining an accurate incentive levels of Direct Load Control (DLC) program using sequential Monte Carlo Simulation (MCS) techniques. The economic analysis of DLC resources needs to identify the hourly-by-hourly expected energy-not-served resulting from the random outage characteristics of generators as well as to reflect the availability and duration of DLC resources, which results the computational explosion. Therefore, the conventional methods are based on the scenario approaches to reduce the computation time as well as to avoid the complexity of economic studies. In this paper, we have developed a new technique based on the sequential MCS to evaluate the required expected load control amount in each hour and to decide the incentive level satisfying the economic constraints. In addition, the mathematical formulation for DLC programs' economic evaluations are developed. To show the efficiency and effectiveness of the suggested method, the numerical studies have been performed for the modified IEEE reliability test system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.514-519
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• 2006

This paper presents a new nonlinear analysis algorithm which uses the equivalent nodal load for the element stiffness. The equivalent nodal load represents the influence of the stiffness change such as the addition of elements, the deletion of elements, and/or the partial change of element stiffness. The nonlinear analysis of structures using the equivalent load improves the efficiency very much because the inverse of the structural stiffness matrix, which needs a large amount of computation to calculate, is reused in each loading step. In this paper, the concept of nonlinear analysis using the equivalent load for the element stiffness is described and some numerical examples are provided to verify it.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.221-223
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• 1997

This paper presents the Simplified Simulation Technique that evaluates the adequacy of an electric power system using only a portion of the outage period instead of each hour. Reliability evaluation may be performed at various hierarchical levels, generation, transmission and distribution system. The Simplified Simulation Technique simplifies the adequacy evaluation process reducing the number of calculations considerably. Therefore the computation time can be significantly reduced. This paper is done to compare the results of the simulation model with the Simplified Simulation Technique against the results of the simulation model without the Simplified Simulation Technique. The reliability indices such as the Loss of Load Probability(LOLP), the loss of load frequency(LOLF), the average duration of load curtailment(DLC) and the average demand of load curtailment(ADLC) are calculated. The proposed methods and procedures are tested by using the IEEE-RTS with 24-bus system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.354-361
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• 2002

This paper propose section properties factor to generate stress history for fatigue analysis and safety inspection of steel bridge. A methodology is described for the computation of numerical stress histories in the steel truss bridge, caused by the vehicles using section properties factor. The global 3-D beam model of bridge is combined with the local shell model of selected details. Joint geometry is introduced by the local shell model. The global beam model takes the effects of joint rigidity and interaction of structural elements into account. Connection nodes in the global beam model correspond to the end cross-section centroids of the local shell model. Their displacements are interpreted as imposed deformations on the local shell model. The load cases fur the global model simulate the vertical unit force along the stringers. The load cases fer the local model are imposed unit deformations. Combining these, and applying vehicle loads, numerical stress histories are obtained. The method is illustrated by test load results of an existing bridge.