• Journal of Korean Institute of Industrial Engineers
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• v.40 no.2
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• pp.223-232
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• 2014

Life-cycle assessment (LCA) is often employed to quantify the environmental impact of a product in a comprehensive manner. The aspects of performance and usability as well as that of eco-friendliness should be considered in an integrated manner for the market competitiveness of an eco-friendly product. The present study developed a product improvement plan for an eco-friendly electric heater by benchmarking two small-size electric heaters (companies 'H' and 'T') in terms of performance, usability, and eco-friendliness. The performance measurements such as temperature, humidity, wind speed, noise, and power consumption were collected while the two heaters were operated in a laboratory setting. Then, the usability evaluations such as aesthetics, operation satisfaction, performance satisfaction, and overall satisfaction were surveyed for the two heaters using a 5-point scale (1 for very unsatisfied and 5 for very satisfied). Lastly, the LCA analysis was conducted by following the six-step process of eco-friendly product design provided by KEITI. The analysis results of the two products being integrated with the aspects of product, service, and user, four design improvement directions such as eco-efficient, smart, modularized, and user-support were recommended for an eco-friendly electric heater. These proposed concepts would be useful to develop an eco-friendly electric heater design with a high level of market competitiveness.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.2
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• pp.301-308
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• 2017

This paper proposes a disturbance observer based controller design method for generating and yawing control of windturbine with two cooperative generators. Windturbine system with two cooperative generators is a distinct structure in which the wind energy supplied by blade axis is converted into electrical energy by two cooperative generators. In this structure, two generators can be controlled independently and therefore they can generate power, simultaneously performing yawing control of nacelle without extra yawing mechanism by cooperatively controlling generating load in appropriate manner. Using this structural trait, this paper designs a disturbance observer based controller that enables the windturbine system with cooperative generators to generate and yaw stably, and verifies the performance of the controller experimentally by applying it to a small-scale windturbine system with the same structure.

• Journal of the Korea Convergence Society
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• v.2 no.4
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• pp.29-37
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• 2011

Dispersed generation (DG) such as wind power (WP) and Photovoltaic systems (PV) that has been promoted at the national level recently is mainly being introduced into distribution systems adjacent to consumers because it is generation on a small scale when compared to current generation. Due to its characteristics, DG can be operated by interconnection with distribution systems to present security of more stable power and efficient use of power facilities and resources. Problems on protection coordination of distribution systems by reverse flow of DG can roughly be divided into three possibilities: excess in rated breaking capacity (12.5KA) of protective devices by a fault in DG current supply, failure to operate protective devices by an apparent effect that can occur by reduction in impedance parallel circuit fault current due to interconnection of DG, and malfunction of protective devices by interconnection transformer connection type. The purpose of this study is to analyze problems in protection coordination that can occur when DG is operated by interconnection with distribution systems by conducting modeling and simulations by using theoretical symmetrical components and MATLAB/SIMULINK to present methods to improve such problems.