• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.2
• /
• pp.15-22
• /
• 2011

Unlike most aerodynamic wind-tunnel, Scramjet Engine Test Facility(SETF) of Korea Aerospace Research Institute should simulate enthalpy condition at a flight condition. SETF is a blow-down type, high-enthalpy wind tunnel. To attain a flight condition, a highly stagnated air comes into the test cell through a supersonic nozzle. Also, an air ejector of the SETF is used for simulating altitude conditions of the engine, and facility starting. SETF has a free-jet type test cell and this free-jet type test cell can simulate a boundary layer effect between an airplane and engine using facility nozzle, but it is too difficult to predict the nature of the facility. Therefore it is required to understand the starting characteristics of the facility by experiments. In this paper, the starting characteristics of the SETF and modifications of the ejector are described.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.451-458
• /
• 2010

Unlike most aerodynamic wind-tunnel, Scramjet Engine Test Facility(SETF) of Korea Aerospace Research Institute should simulate enthalpy condition at a flight condition. SETF is a blow-down type, high-enthalpy wind tunnel. To attain a flight condition, a highly stagnated air comes into the test cell through a supersonic nozzle. Also, an air ejector of the SETF is used for simulating altitude conditions of the engine, and facility starting. SETF has a free-jet type test cell and this free-jet type test cell can simulate a boundary layer effect between an airplane and engine using facility nozzle, but it is too difficult to predict the nature of the facility. Therefore it is required to understand the starting characteristics of the facility by experiments. In this paper, the starting characteristics of the SETF and modifications of the ejector are described.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.68 no.1
• /
• pp.44-51
• /
• 2019

Tunnel Boring Machine's Technology has depends mostly on imports, currently domestic technology development was proceeding. There are many technologies in this field, above all, the large-capacity motor drive technology required for excavation is one of the core technologies. In particular, when several large motors are simultaneously starting, there are many problems due to a large starting current at that time, and it is difficult to design and operate a power receiving facility. In this paper, A method of reducing the starting current by using the regenerative power generated by the deceleration of the motor has been studied. To verify this proposal, we designed the induction motor controller using CAE based power simulation tool and verified the results of the proposed method by applying the reduced model. As a result, it is possible to reduce the maximum starting current and shorten the start-up time. Moreover, even if several motors are connected to one bank, it is proved that the method can be efficiently operated by using the sequential braking / starting sequence. In the case of a power system in which a large capacity electric motor such as a tunnel excavation system is driven, the results of this study are expected to be a stable and effective method for solving the start-up current problem and designing the power receiving facility.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.57 no.2
• /
• pp.146-152
• /
• 2008

The frequency of lightning is increased due to improbable weather condition and global wanning. This phenomenon increases economical damage as well as human damage. Advanced countries like europe and north america have applied the facility standard of lightning by accumulating a store of quantitative data about lightning research. Lightning facility is composed of the lightning accepting part for induction lightning, ground connected electrode which conducts lightning current. The lightning accepting part is composed of normal rod, horizontal conductor, ESE lightning rod. Moreover, lightning accepting part is taken to use by the method of protection. This paper suggests HEC(Hybrid ESE-Conductor) method which mixes horizontal conductor and ESE lightning rod. This is also discovered by experiment that the starting point of corona discharge current is low, so it is efficient for lightning protection comparing with other methods. Moreover, distribution of electric field is analyzed qualitatively by finite element method. It also results in the relation of the starting point of corona discharge current. Corona discharge current makes minute current about some ${\mu}A$ between the electrodes by the strength of electric field. Also it occurs insulation destruction of gas, and it is developed to the shape of streamer by increase of the strength of electric field. We can find that the initial occurrence of streamer and contact probability of lightning can have advantage after researching the starting point of corona discharge current and discharge current of lightning striking point. This research demonstrates that the suggested HEC method is economically competitive as a lightning protection facility, and it takes a capably perfect role.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.3
• /
• pp.433-441
• /
• 2022

In general, in an emergency generator system for an electric facility including an induction motor load, an emergency power generation facility larger than the facility load capacity is built due to the initial starting current of the induction motor. In order to reduce this economic burden, various methods to reduce the inrush current of induction motors are applied to suppress the additional expansion of generators due to the reduction of power generation facilities and the increase in electrical facilities. Among these methods, when a system with a built-in soft start function of an induction motor using an inverter is built, it is the best way to reduce the inrush current of the induction motor to less than the rated current. However, in this case, the installation cost of the inverter to drive the induction motor increases. This paper proposes a soft start method of an induction motor by expanding the frequency and voltage control operation area of an emergency generator. In addition, proposed a speed calculation method based on power factor information, which is essential information for stable soft start of an induction motor, and a method for generating a speed command value of the governor for starting with maximum torque.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10a
• /
• pp.286-291
• /
• 1990

We studied about the adopted system to POSCO facility which is very complexity and various as an example for studying a facility diagnosis and management system that is starting to be distinguished in the nowadays. At the first, explain what's the background why POSCO adopted the system, and it's goal, and it's promoting direction and ways. And there after studied it's results and effective analysis. Finally inquiry about the future improvement and development items through problems which become known during the project periods.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.17 no.4
• /
• pp.63-72
• /
• 2013

A Mach 5 nozzle and a diffuser of the Scramjet Engine Test Facility (SETF) were made for a hydrocarbon-fueled scramjet engine. SETF, attached with a diffuser guide, started with a model of 60% blockage, though the model engine could not start by over expansion of the facility nozzle. The model was moved into the nozzle to escape the shock generated from the nozzle exit, both SETF and the engine could start. The pitot rake experiments (blockage of 2.3%) were done for measuring the core flow in the test section. From the pitot experiments, the core flow was expanded by an under expansion. It means that the core flow in the test section was related with a model blockage. SETF and the engine with a blockage of 33% work normally. From a series of experiments, SETF started with a normal shock efficiency of 58%, regardless of a blockage ratio.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2003.10a
• /
• pp.303-308
• /
• 2003

Facility management system has been studied recently due to its increasing demand. As a starting step it is necessary to create 3-D shape of the facility. In this study, we attempted to create 3-D shape of the buildings by fusing the raster and vector information. the raster information comes from stereo aerial photographs and the vector information comes from the existing 2-D digital map. GPS surveying and data conversion using ACAD and ARCINFO also performed to extract building height from stereo aerial photographs. Finally we could be able to perform semi-automatic 3-D building modeling with fusion of two sources of information.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 1995.10a
• /
• pp.110-114
• /
• 1995

Subscriber-Unit(SU) method in apartment-housing is used as the plan for the Cable-TV(CATV) receiving facility. But it is decided to apply Notification NO.1994-18 of the Ministry of Communications regulations starting in march, 10.1994. In this study, a new plan of CATV-receiving facility according to the Notification NO.1994-18 is suggested, and it is designed to apply lone-wire from an amplifier box to a SU or another amplifier box. Proposed results adopt the Head End(HE) to introduc Integrated Service Digital Network(ISDN) and to raise added-value of apartment-housing.

• Journal of Korean Society of Water and Wastewater
• /
• v.27 no.5
• /
• pp.581-590
• /
• 2013

A research was performed for zero discharge system of waste water which is produced from energy recovery process of waste and biomass. Leachate and all kinds of waste water should be separated and integrated into three categories in addition to converting existing leachate treatment facility into waste water treatment facility as well as introducing a management system of reverse osmosis membrane facility and bioreactor landfill. Following these conditions to better water treatment process, it was likely to produce over 3,000 tons of low-grade recycling water and 2,000 tons of high-grade recycling water per day when zero discharge system of waste water is applied starting from 2016. Economical efficiency was also surveyed in total treatment fee. Present system costs 18,129 million won per year, and suggested zero discharge system would cost 15,789 million won per year.