• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.413-421
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• 2013

This paper proposes residential hybrid distribution system that can supply AC power and DC power to AC load and DC load at the same time. This hybrid distribution system consists of three parts: bidirectional inverter, step-up converter and step-down converter. Also that is used to supply voltage to home application is classified of AC load and DC load as load characteristics. The performance of proposed hybrid distribution system is validated through the hardware implementation and the experimental results.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.106-112
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• 2000

Since the oil crisis, we have been concerned about the energy saving techniques of electric generating systems. As a part of the effort to save energy, automatic electric load sharing device was developed. Usually, ship's electric generating system consists of two or three sets of generator. And, electric generating system is operated as single or parallel operation mode according to the demanded electric power. Therefore, it is important to investigate generators operating mode for the supply of required electric power in the ship in order to decrease the operating cost. So, this paper suggests the method to solve the optimal electric load distribution problem by dynamic programming. And, this thesis indicates that the proposed method is superior to the lagrange multiplier's method in obtaining optimal load distribution solution in the ship's electric generating system.

• Structural Engineering and Mechanics
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• v.33 no.5
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• pp.589-604
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• 2009

In the field of predicting structural safety and reliability the operating conditions play an essential role. Since the time and cost limitations are a significant factors in engineering it is important to predict the future operating conditions as close to the actual state as possible from small amount of available data. Because of the randomness of the environment the shape of measured load spectra can vary considerably and therefore simple distribution functions are frequently not sufficient for their modelling. Thus mixed distribution functions have to be used. In general their major weakness is the complicated calculation of unknown parameters. The scope of the paper is to investigate the load spectra growth for actual operating conditions and to investigate the modelling and extrapolation of load spectra with algorithm for mixed distribution estimation, REBMIX. The data obtained from the measurements of wheel forces and the braking moment on proving ground is used to generate load spectra.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.9
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• pp.513-520
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• 2003

Service restoration is an emergency control in distribution constrol centers to restore out-of-service area as soon as possible when a fault occurs in distribution networks. therefore, it requires fast computation time and high quality solutions for load balancing. In this paper. a load balance index and heuristic guided best-first search are proposed for these problem. The proposed algorithm consists of two parts. One is to set up a decision tree to represent the various switching operations available. Another is to identify the most effective the set of switches using proposed search technique and a load balance index. Test results on the KEPCO's 108 bus distribution system show that the performance is efficient and robust.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.830-836
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• 2011

Most of pitch/yaw reducers consist of several planetary geartrains. Planetary geartrains make gearboxes to be small and light, low noise and good efficiency. Most important thing in the planetary geartrain is load distribution on the gear tooth flank. In this study, the effect of output shaft bearings on the load distribution of gear tooth flank has been investigated. The commercial software was employed to compare the load distribution of two models depending on the bearing type. The spherical roller bearing(SRB) and the cylindrical roller bearing(CRB) were used as output shaft bearings in the $1^{st}$ model, and two taper roller bearings(TRB) were used in the $2^{nd}$ model. As a result, it was found that the $2^{nd}$ model. showed better performances on the load distribution of gear tooth flank, this results stated that the output shaft bearing system could be important consideration when designing reducers for wind turbine systems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.821-829
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• 2006

Traffic load comprise primary input to pavement design causing pavement damage. therefore it should be proceeded suitable traffic load distribution modeling for pavement design and analysis. Traffic load have been represented by equivalent single axle loads (ESALs) which convert mixed traffic stream into one value for design purposes. But there are some limit to apply ESALs to other roads because it is empirical value developed as part of the original AASHO(American Association of State Highway Officials) road test. There have been many efforts to solve these problems. Several leading country have implemented M-E(Mechanistic-Empirical) design procedures based on mechanical concept. As a result, they established traffic load quantification method using load distribution model known as Axle Load Spectra. This paper details Axle Load Spectra and presents axle load distribution model based on normal mixture distribution function using truck load data collected by WIM system installed in national highway. Axle load spectra and axle load distribution model presented in this paper could be useful for basic data when making traffic load quantification plan for pavement design, overweight vehicle permit plan and pavement maintenance cost plan.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.3
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• pp.313-319
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• 2002

Since the oil crisis in 1970, a great deal of effort has been made to develop automatic electric load sharing systems as a part of the efforts to save energy. A large scale electric generating system composes more than two generators whose characteristics may be different. When such a system is operated individually or in parallel, the lagrange multiplier's method has difficulty in achieving optimal load distribution because generators usually have the limitations of the operating range with inequality constraints. Therefore, a suitable operating mode of generators has to be decided according to the selection of the generators to meet electric power requirements at the minimum cost. In this study, a method which solves the optimal electric load distribution problem using the dynamic programming technique is proposed. This study also shows that the dynamic programming method has an advantage in dealing with the optimal load distribution problem under the limitations of the operating range with inequality constraints including generator operation mode. In this study, generator operating cost curve of second order equation by shop trial test results of diesel generators are used. The results indicate that the proposed method can be applied to the ship's electric generating system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.5
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• pp.266-274
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• 2004

This paper presents a scheme for the interconnection of dispersed generator systems(DGs) based on load .unbalance and load model in composite distribution systems. Groups of each individual load model consist of residential, industrial, commercial, official and agricultural load. The unbalance is involved with many single-phase line segment. . Voltage profile improvement and system loss minimization by installation of DGs depend greatly on how they are placed and operated in the distribution systems. So, DGs can reduce distribution real power losses and replace large-scale generators if they are placed appropriately in the distribution systems. The main idea of solving fuzzy goal programming is to transform the original objective function and constraints into the equivalent multi-objectives functions with fuzzy sets to evaluate their imprecise nature for the criterion of power loss minimization, the number or total capacity of DGs and the bus voltage deviation, and then solve the problem using genetic algorithm. The method proposed is applied to IEEE 13 bus and 34 bus test systems to demonstrate its effectiveness.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.7
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• pp.478-485
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• 2008

The extreme steam temperature deviation experienced in the superheater of a tangentially fired boiler can seriously affect its economic and safe operation. This temperature deviation is one of the main causes of boiler tube failures. The steam temperature deviation is mainly due to the thermal load deviation in the lateral direction of the superheater. The thermal load deviation consists of several causes. One of the causes is the non-uniform heat flow distribution of burnt gas on the superheater tube system. This distribution is very difficult to measure in situ using direct experimental techniques. So, we need thermal load model to estimate the tube temperature. In this paper, we propose a thermal load distribution model by using CFD analysis and plant data. We successfully predict the tube temperature and the steam flow rate in a final superheater system from the thermal load model and one dimensional heat-flow system analysis. The proposed model and analysis method would be valuable in preventing the frequent tube failure of the final superheater tubes.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.414-416
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• 1992

Stability analysis and load distribution problem of two coordinating robots using full dynamic model is studied in this paper. Dynamic models of two robots are combined with the position force control strategy and the Liapunov 2nd method is used for the proof of the stability. This analysis shows that the position and force control of two coordinating robot is always stable. Also, load distribution problem is mentioned with respect to the end-effector forces minimizing joint torques.