• Journal of Electrical Engineering and Technology
• /
• v.11 no.1
• /
• pp.65-75
• /
• 2016

Aiming at analyzing the power flow of the distribution systems with distribution transformer (DT) branches and PV nodes, a hybrid three-phase power flow methodology is presented in this paper. The incidence formulas among node voltages, loop currents and node current injections have been developed based on node-branch incidence matrix of the distribution network. The method can solve the power flow directly and has higher efficiency. Moreover, the paper provides a modified method to model DT branches by considering winding connections, phase shifting and off-nominal tap ratio, and then DT branches could be seen like one transmission line with the proposed power flow method. To deal with the PV nodes, an improved approach to calculate reactive power increment at each PV node was deduced based on the assumption that the positive-sequence voltage magnitude of PV node is fixed at a given value. Then during calculating the power flow at each iteration, it only needs to update current injection at each PV node with the proposed algorithm. The process is very simple and clear. The results of IEEE 4 nodes and the modified IEEE 34 nodes test feeders verified the correctness and efficiency of the proposed hybrid power flow algorithm.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.10 no.2
• /
• pp.147-151
• /
• 2005

Serious attempt for the improvement of quality parameters in silkworm hybrids came rather very late in India. Realising the need for productive breeds to the field and reorientation in breeding methodology, the silkworm breeders of CSRTI, Mysore were able to develop silkworm breeds with fine denier namely, JPN7, CSR48, B63 and B65 of specific industrial requirement through directional selection. As the success of silkworm breeds mainly depends on their combining ability, the developed breeds were subjected for hybrid evaluation. Out of 42 bivoltine hybrids studied, one hybrid, $CSR48{\times}CSR5$ was identified for its superiority over the existing bivoltine hybrids namely $CSR2{\times}CSR4,\;CSR2{\times}CSR5\;and\;CSR18{\times}CSR19$ for majority of qualitative traits. Post cocoon testing of large quantity of cocoons of $CSR48{\times}CSR5$ resulted in the production of high quality '3A'grade silk. It is for the first time in the Indian Sericulture industry that high quality silk with longer filament length of 1474 m, denier of 2.47, standard size deviation of 0.983 d, maximum size deviation of 1.322, neatness of 96 p, reelability of $85\%$, tenacity of 3.87 g/d, elongation of $22.32\%$ and cohesion of 110 strokes was produced. The superiority of fine denier silkworm breeds and their hybrids are discussed.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.11
• /
• pp.61-68
• /
• 2004

Today almost all chips have IEEE 1149.1 tap controller inside. Recently the circuit is embedded in the chips for other functional objectives. Hence a CED technique for testing and monitoring the IEEE 1149.1 tap controller had been proposed. This paper studies the optimal CED test technique on the IEEE 1149.1 tap controller. There are duplication, parity prediction, and hybrid techniques. The hybrid technique shows the best result on the area overhead. This means that the hybrid technique is perfectly adequate for the IEEE 1149.1 tap controller to be applied to test with the optimal area overhead and can be used widely in the field. Furthermore, we made more reduction from the previous method resulting in less area overhead.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.7 no.6
• /
• pp.1-7
• /
• 2003

This paper presents a novel hybrid time-frequency-domain method for nonlinear soil-structure interaction(SSI) analysis. It employs, in a practical manner, a computer code for equivalent linear SSI analysis and a general-purpose nonlinear finite element program. The proposed method first (calculates dynamic responses on a truncated finite element boundary utilizing an equivalent linear SSI program in the frequency domain. Then, a general purpose nonlinear finite element program is employed to analyze the nonlinear SSI problem in the time domain, in which boundary conditions at the truncated boundary are imposed with the responses calculated in the previous frequency domain SSI analysis, In order to validate the proposed method, seismic response analyses are carried out for a 2-D underground subway station in a multi-layered half-space, For the analyses, a equivalent linear SSI code KIESSI-2D is coupled to ANSYS program. The numerical results indicate that the proposed methodology can be a viable solution for nonlinear SSI problems.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.2
• /
• pp.156-173
• /
• 2004

Business process should support the execution of collaboration process with agility and flexibility through the integration of enterprise inner or outer applications and human resources from the collaborative workflow view. Although the dependency of enterprise activities to the automated system has been increasing, human role is as important as ever. In the workflow modelling this human role is emphasized and the structure to control human error by analysing decision-making itself is needed. Also, through the collaboration of activities agile and effective communication should be constructed, eventually by the combination and coordination of activities to the aimed process the product quality should be improved. This paper classifies human errors can be occurred in collaborative workflow by applying GEMS(Generic Error Modelling System) to control them, and suggests human error control method through hybrid based modelling as well. On this base collaborative workflow modeling tool is designed and implemented. Using this modelling methodology it is possible to workflow modeling could be supported considering human characteristics has a tendency of human error to be controlled.

• Nuclear Engineering and Technology
• /
• v.51 no.8
• /
• pp.1905-1915
• /
• 2019

This paper investigated the influence of simple support girds on flow, irrespective of having mixing vanes, in a 1 × 3 array rod bundle by using CFD methodology and the most accurate turbulence model which could reflect the actual physics of the flow was determined. In this context, a CFD model was created simulating the experimental studies on a single-phase flow [1] and the results were compared with the experimental data. In the first part of the study, influence of mesh was examined. Tetra, hybrid and poly type meshes were analyzed and convergence study was carried out on each in order to determine the most appropriate type and density. k - ε Standard and RSM LPS turbulence models were used in this section. In the second part of the study, the most appropriate turbulence model that could reflect the physics of the actual flow was investigated. RANS based turbulence models were examined using the mesh that was determined in the first part. Velocity and turbulence intensity results obtained on the upstream and downstream of the spacer grid at -3d_h, +3d_h and +40d_h locations were compared with the experimental data. In the last section of the study, the behavior of flow through the spacer grid was examined and its prominent aspects were highlighted on the most appropriate turbulence model determined in the second part. Results of the study revealed the importance of mesh type. Hybrid mesh having the largest number of structured elements performed remarkably better than the other two on results. While comparisons of numerical and experimental results showed an overall agreement within all turbulence models, RSM LPS presented better results than the others. Lastly, physical appearance of the flow through spacer grids revealed that springs has more influence on flow than dimples and induces transient flow behaviors. As a result, flow through a simple support grid was examined and the most appropriate turbulence model reflecting the actual physics of the flow was determined.

• Journal of the Korea Society of Computer and Information
• /
• v.10 no.4 s.36
• /
• pp.259-274
• /
• 2005

In this paper, we propose a methodology to estimate the number of users in e-Commerce systems. There have been a lot of previous work under the closed-LAN system environment. But the study on the number of acceptable users in real network environment is hard to find in the literature. Our research applies a Hybrid Simulation by using QoS results for end-to-end high-speed Internet service, and experiments are performed with regard to LAN and WAN, network equipments, and various network bandwidth. As result of the experiments we observed that the response time of high-speed Internet service media(Wireless LAN, ADSL, Cable, VDSL) depends heavily on the sequence and depth of transactions and on the ratio of transactional and non-transactional interactions. That is, as the network and application get more loads, the number of acceptable users decreases. By adding a cache server and an L4 switch to the simulation model, we analysed the changes in the number of users and client response time.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.4
• /
• pp.300-308
• /
• 2019

For drones to be used for industrial or agricultural applications, it is necessary to increase the payload and endurance. Currently, the payload and endurance are limited by the battery technology for electric powered drones. In addition, charging or replacing the batteries may not be a practical solution at the field that requires near continuous operation. In this paper, a procedure to optimize the power system of an electric hybrid drone that consists of an internal combustion engine, a generator, a battery, and electric motors is presented. The example drone for crop dusting is sized for easy transportation with a maximum takeoff weight of 200 kg. The two main rotors that are mechanically connected to the internal combustion engine provides most of the lift. The drone is controled by four electric motors that are driven by the generator. By analyzing the flow of the energy, a methodology to select the optimum propeller and motor among the commercially available models is described. Then, a procedure of finding the optimum operational condition along with the proper gear reduction ratios for the internal combustion engine based on the test data is presented.

• Advances in concrete construction
• /
• v.10 no.6
• /
• pp.547-557
• /
• 2020

This paper presents one of the demonstration projects undertaken during the FP7 EU-funded Anagennisi project (Innovative reuse of all tyre components in concrete-2014-2017) on a full-scale (30 m×40 m, thickness: 0.2 m) Steel Fibre Reinforced Concrete (SFRC) slab-on-grade using a blend of manufactured steel fibres (MSF) and Recycled Tyre Steel Fibres (RTSF). The aim of the project was to assess the use of RTSF in everyday construction practice. The Anagennisi partners, Dulex Ltd in collaboration with Gradmont-Gradacac Ltd and University of Zagreb, designed, cast and monitored the long-term shrinkage deformations of the indoor slab-on-grade slab at Gradmont's precast concrete factory in Gradacac, Bosnia and Herzegovina. A hybrid RTSF mix (20 kg/㎥ of MSF+10 kg/㎥ of RTSF) was used to comply with the design criteria which included a maximum load capacity of 20 kN/㎡. The slab was monitored for one year using surveying equipment and visual inspection of cracks. During the monitoring period, the slab exhibited reasonable deformations (a maximum displacement of 3.3 mm for both, horizontal and vertical displacements) whilst after five years in use, the owners did not report any issues and were satisfied with the construction methodology and materials used. This work confirms that RSTF is a viable and sustainable solution for slab-on-grade applications.

• Journal of Korea Society of Industrial Information Systems
• /
• v.27 no.4
• /
• pp.37-45
• /
• 2022

In this paper, a multi agent-multi task assignment problem, which is a representative problem of combinatorial optimization, is presented. The objective of the problem is to determine the coordinated agent-task assignment that maximizes the sum of the achievement rates of each task. The achievement rate is represented as a concave down increasing function according to the number of agents assigned to the task. The problem is expressed as an NP-hard problem with a non-linear objective function. In this paper, to solve the assignment problem, we propose a hybrid cross-entropy algorithm as an effective and efficient solution methodology. In fact, the general cross-entropy algorithm might have drawbacks (e.g., slow update of parameters and premature convergence) according to problem situations. Compared to the general cross-entropy algorithm, the proposed method is designed to be less likely to have the two drawbacks. We show that the performances of the proposed methods are better than those of the general cross-entropy algorithm through numerical experiments.