• Journal of Electrical Engineering and Technology
• /
• v.11 no.5
• /
• pp.1311-1315
• /
• 2016

• Progress in Superconductivity and Cryogenics
• /
• v.23 no.3
• /
• pp.14-19
• /
• 2021

The reduction of carbon dioxide emissions becomes a global issue, the main source of carbon dioxide emissions in the Asian region is the energy conversion sector, especially coal-fired power plants. We are working to develop technologies that will at least limit the increase in carbon dioxide emissions from the thermal power plants as one way to reduce carbon dioxide emissions. Our research aims to reduce carbon dioxide emissions by removing iron oxide scale from the feedwater system of thermal power plants using a superconducting high-gradient magnetic separation (HGMS) system, thereby reducing the loss of power generation efficiency. In this paper, the background of thermal power plants in Asia is outlined, followed by a case study of the introduction of a chemical cleaning line at an actual thermal power plant in Japan, and the possibility of introducing it into the thermal power plants in China based on the results.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2524-2527
• /
• 2007

Solid propellant gas generators (SPGG) play a role as a turbopump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start. For such a purpose, the propellants should burn with a relative low flame temperature and the combustion gas should not contain corrosive constituents such as chlorine compounds. In accordance with these requirements, stabilized AN-based propellants have been usually used as the most appropriate oxidizer for propellant compositions. However, the burning area of the propellant intends to increase to satisfy the required mass flux because of its low burning rate. Consequently the burning area incensement brings on the SPGG size augmentation. A flow restriction such as filters is applied to decrease the SPGG size by rising up the combustion pressure resulting in increasing the burning rate. The feasibility of the size reduction of SPGG by the employment of filters have been studied. The preliminary results of this study show that the considerable reduction of SPGG size would be achievable just by installing a filter with relatively high pressure loss coefficient.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.6
• /
• pp.350-358
• /
• 2017

Recently, owing to increased interest in low-carbon energy supplies, renewable energy sources such as photovoltaics and wind turbines in distribution networks have received considerable attention for generating clean and unlimited energy. The presence of energy storage systems (ESSs) in the promising field of active distribution networks (ADNs) would have direct impact on power system problems such as encountered in probabilistic distributed generation (DG) model studies. Hence, the optimal procedure is offered herein, in which the simultaneous placement of an ESS, photovoltaic-based DG, and wind turbine-based DG in an ADN is taken into account. The main goal of this paper is to maximize the net present value of the loss reduction benefit by considering the price of electricity for each load state. The proposed framework consists of a scenario tree method for covering the existing uncertainties in the distribution network's load demand as well as DG. The collected results verify the considerable effect of concurrent installation of probabilistic DG models and an ESS in defining the optimum site of DG and the ESS and they demonstrate that the optimum operation of an ESS in the ADN is consequently related to the highest value of the loss reduction benefit in long-term planning as well. The results obtained are encouraging.

• Journal of the Korean Society for Precision Engineering
• /
• v.34 no.4
• /
• pp.287-292
• /
• 2017

A gas turbine is the main equipment used in a combined heat and power plant. It generates a high sound pressure noise level. To reduce the noise level, an enclosure is installed around the turbine. The sound insulation performance of the enclosure affects the amount of external noise reduction. In this study, a sound transmission loss analysis is performed using the boundary element method to predict sound insulation performance according to the numbers and shapes of the supporter. Radiated noise analysis is also performed for the main external points of the enclosure using ray-acoustics. The results of these analyses are presented and a design plan is proposed that reduces the sound pressure noise level of the enclosure.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.50 no.2
• /
• pp.76-82
• /
• 2001

This paper presents a approach for a service restoration and optimal reconfiguration of distribution network using Genetic algorithm(GA) and Tabu search(TS) method. Restoration and reconfiguration problems in distribution network are difficult to solve in short times, because distribution network supplies power for customers combined with many tie-line switches and sectionalizing switches. Furthermore, the solutions of these problems have to satisfy radial operation conditions and reliability indices. To overcome these time consuming and sub-optimal problem characteristics, this paper applied Genetic-Tabu algorithm. The Genetic-Tabu algorithm is a Tabu search combined with Genetic algorithm to complement the weak points of each algorithm. The case studies with 7 bus distribution network showed that not the loss reduction but also the reliability cost should be considered to achieve the economic service restoration and reconfiguration in the distribution network. The results of suggested Genetic-Tabu algorithm and simple Genetic algorithm are compared in the case study also.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.93-97
• /
• 2001

A new compact, low-energy electron beam irradiator has been developed. The core-loss of silicon steels can be reduced by magnetic-domain refinement method. The irradiator was developed for the application of core-loss reduction using the method. The beam energy of the irradiator can be varied from 35 to 80 keV and the maximum current is 3mA. The irradiation area is designed to be $30\times30mm2$ now and will be upgraded to $30\times150mm2$ using a scanning magnet and scanning cone. The electron beam generated from 3 mm diameter LaB6 is extracted to the air for the irradiation of the silicon steels in the air. A special irradiation port was developed for this low-energy irradiator. A havar foil with $4.08{\mu}m$ thickness were used for the window and a cold air-cooling system keeps the foil structure by removing heat at the window. The irradiator system and its operation characteristics will be discussed.

• Journal of Convergence for Information Technology
• /
• v.12 no.3
• /
• pp.294-301
• /
• 2022

In this study, a multi-layer cascade (MLC) electrical array configuration method for thermoelectric generator consisting of plural number of thermoelectric modules (TEMs) was proposed to reduce mismatch loss caused by temperature maldistribution on the surfaces of the TEMs. To validate the effect of MLC on the mismatch loss reduction, a numerical model capable of reflecting multi-physics phenomena occuring in the TEMs was developed. MLC can be employed by placing a group of TEMs experiencing relatively low temperature differences in an electric layer with more electrical branches while locating a group of TEMs experiencing relatively high temperature differences in an electric layer with less electrical branches. The TEMs were classified using the temperature distribution obtained by the numerical model. A MLC with an optimal electrical branch ratio showed a 96.5% of electric power generation compared to an ideal case.

• Journal of IKEEE
• /
• v.16 no.4
• /
• pp.283-289
• /
• 2012

In this paper, We proposed Separate Gate Technique(SGT) to improve the switching characteristics of Trench power MOSFET. Low gate-to-drain 전하 (Miller 전하 : Qgd) has to be achieved to improve the switching characteristics of Trench power MOSFET. A thin poly-silicon deposition is processed to form side wall which is used as gate and thus, it has thinner gate compared to the gate of conventional Trench MOSFET. The reduction of the overlapped area between the gate and the drain decreases the overlapped charge, and the performance of the proposed device is compared to the conventional Trench MOSFET using Silvaco T-CAD. Ciss(input capacitance : Cgs+Cgd), Coss(output capacitance : Cgd+Cds) and Crss(reverse recovery capacitance : Cgd) are reduced to 14.3%, 23% and 30% respectively. To confirm the reduction effect of capacitance, the characteristics of inverter circuit is comprised. Consequently, the reverse recovery time is reduced by 28%. The proposed device can be fabricated with convetional processes without any electrical property degradation compare to conventional device.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.293-298
• /
• 2002

Recycling of coal combustion by-product(Ash) are becoming more improtant in the utilization business as a result of the increased use of NOx reduction technologies at coal-fired power plants. current disposal methods of these by-products create not only a loss of profit for the power industry, but also environmental concerns that breed negative public opinion. This research made concrete crecast block using coal ash artificial aggregate for environmental-friendly products and compared strength special quality of this block with existent common use brick and analyzed application possibility in situ with a reserve experiment that measured strength property and manufactured method to handle coal ash produced in Bo-ryung thermoelectric power plant.