• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.66-70
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• 2007

For the design to prevent the saturation of the iron core and the effective fault current limitation, the analysis for the operation of the flux-lock type superconducting fault current limiter (SFCL) with consideration for the hysteresis characteristics of the iron core is required. In this paper, the hysteresis characteristics of the flux-lock reactor, which is an essential component of the flux-lock type SFCL, were investigated. Under normal condition, the hysteresis loss of the iron core in the flux-lock type SFCL does not happen due to its winding structure. From the equivalent circuit for the flux-lock type SFCL and the fault current limiting experiments, the hysteresis curves could be drawn. From the analysis for both the hysteresis curves and the fault current limiting characteristics due to the number of turns for the 1st and 2nd windings, the increase of the number of turns in the 2nd winding of the flux-lock type SFCL had a role to prevent the iron core from saturation.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2142-2148
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• 2015

This paper proposes novel real-time footstep planning and following methods for the navigation of humanoid robots. A footstep command is defined by a walking direction and step lengths for footstep planning. The walking direction is determined by a uni-vector field navigation method, and the allowable yawing range caused by hardware limitation is considered. The lateral step length is determined to avoid collisions between the two legs while walking. The sagittal step length is modified by a binary search algorithm when collision occurs between the robot body and obstacles in a narrow space. If the robot body still collides with obstacles despite the modification of the sagittal step length, the lateral step length is shifted at the next footstep. For footstep following, a walking pattern generator based on a 3-D linear inverted pendulum model is utilized, which can generate modifiable walking patterns using the zero-moment point variation scheme. Therefore, it enables a humanoid robot to follow the footstep command planned for each footstep. The effectiveness of the proposed method is verified through simulation and experiment.

• Korean Institute of Interior Design Journal
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• v.14 no.6 s.53
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• pp.103-111
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• 2005

Since the Industrial Revolution in the 18th century, the production system adopted mechanization and mass production to popularize and standardize overall society. The architectural space removed basic desire of men on the decoration to neglect historical and regional continuity of the architecture and to make uniform designs, so that human sensibility and emotion were excluded. The architectural space had arbitrary and functionalism features in accordance with such a social change to display abstract space having no personality. The limitation expanded value of the space that was not lot possession and residence but for communication with men to express object factors. However, the object factors of the space were expressed in each factor consisting of either material factors or non-material factors. This study investigated interaction of the space by both expressive interaction and potential interaction to find out key words for making frames of the investigation and to examine cases comprehensively. The purpose of the study was to recover relations between the space and men in horizontal way and mutual communication and to present possibility integrating men and space.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.238-240
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• 2007

This paper present adaptation method of rail potential test to verify DC railway system's performance and safety. For protection of person and utility caused by rail potential rise, international standard to limit rail potential rise is made and rail potential is tested at the time of plan and construction of DC railway system in foreign country. So, we need rail potential test at the opening time and prepare a continuous monitoring technique of rail potential and a limitation method of rail potential rise. For these, we describe cause of rail potential rise, international standard about rail potential, protection principle, an example of calculation and measurement, and adaptation method for performance test.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.110-113
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• 2007

Modernity which is superficial phenomenon set off the mass scale for mass consumption and provide uniformly artificial environment. But natural destruction, environment pollution, resources exhaustion and so on has been caused by this and now ecology is threatened by destruction and damage beyond the limitation and human beings survival is even threatened. Accordingly furniture development for environment preservation considered environment problem is the urgent real situation. Recent paradigm is the concept of Eco-design which is the green design possible to live together in symbiosis, and new types of alternative furniture are needed in Korea as well. 'Furniture for disassembly' is presented as new method for alternative furniture.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.281-284
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• 2007

Today, in space design boundaries between spaces have become obscure and space images are changed and overlap each other. Moreover, with the digital technology creating more informational spaces with various interactions, the set up of intelligent space has been made possible in reality. As if to deny the law of physical limitation, interfaces are used as main concept in structuring and expressing the spaces. It appears once again when each section is an expressional factor of interfaces and when meanings are produced through the systemization. Here this study analyzes the hybrid action that appear in contemporary space design. At the very moment, interface emerged as an important concept, defining contemporary space design in a very different way and present interface as a new possibility in space.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2058-2064
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• 2014

In transformer fault diagnosis, dissolved gas analysis (DGA) is been widely employed for a long period and numerous methods have been innovated to interpret its results. Still in some cases it fails to identify the corresponding faults. Due to the limitation of training data and non-linearity, the estimation of key-gas ratio in the transformer oil becomes more complicated. This paper presents Intuitionistic Fuzzy expert System (IFS) to diagnose several faults in a transformer. This revised approach is well suitable to diagnosis the transformer faults and the corresponding action to be taken. The proposed method is applied to an independent data of different power transformers and various case studies of historic trends of transformer units. It has been proved to be a very advantageous tool for transformer diagnosis and upkeep planning. This method has been successfully used to identify the type of fault developing within a transformer even if there is conflict in the results of AI technique applied to DGA data.

• Industrial Engineering and Management Systems
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• v.6 no.2
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• pp.106-118
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• 2007

This paper present a new optimization model to generate aggregate production planning by considering electric cost. The new Time Of Switching (TOS) electric type is introduced by switching over Time Of Day (TOD) and Time Of Use (TOU) electric types to minimize the electric cost. The fuzzy demand and Dynamic inventory tracking with multiple plant capacity are modeled to cover the uncertain demand of customer. The constraint for minimum hour limitation of plant running per one start up event is introduced to minimize plants idle time. Furthermore; the Optimal Weight Moving Average Factor for customer demand forecasting is introduced by monthly factors to reduce forecasting error. Application is illustrated for multiple cement mill plants. The mathematical model was formulated in spreadsheet format. Then the spreadsheet-solver technique was used as a tool to solve the model. A simulation running on part of the system in a test for six months shows the optimal solution could save 60% of the actual cost.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.2043-2050
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• 2017

This paper presents two MPC (Model Predictive Control) based charging and discharging algorithms of BESS (Battery Energy Storage System) for capacity firming of wind generation. To deal with the intermittency of the output of wind generation, a single BESS is employed. The proposed algorithms not only make the output of combined systems of wind generation and BESS track the predefined reference, but also keep the SoC (State of Charge) of BESS within its physical limitation. Since the proposed algorithms are both presented in simple if-then statements which are the optimal solutions of related optimization problems, they are both easy to implement in a real-time system. Finally, simulations of the two strategies are done using a realistic wind farm library and a BESS model. The results on both simulations show that the proposed algorithms effectively achieve capacity firming while fulfilling all physical constraints.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.59-67
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• 2000

This paper describes the unified reliability evaluation with partial loss of continuity for Inchon international airport distribution system which is complex and difficult system to implement. To evaluate reliability considering line limitation and voltage drop of the system, PLOC technique which is based on deterministic evaluation technique and failure mode & effective analysis method is employed. And reliability indices calculation method is used. Finally, to evaluate the system performance and to improve the reliability of the system, Analytic network process method is employed. As a result, calculating accurate reliability, finding weak points, and expansion scheduling of the system is possible.