• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1125-1129
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• 2015

Increasing peak load is one of the major concerns about operation of urban railroad systems. Since ESSs (Energy Storage Systems) have a great potential for shaving the peak load, there has been a growing interest in the use of ESS for peak load reduction. Also, ESS can be optimally scheduled to minimize the electricity purchasing cost under a given ToU (Time-of-Use) tariff by taking advantage of electricity price difference between peak and off-peak time. This paper presents a Mixed Integer Programming (MIP)-based ESS scheduling method to minimize the electricity purchasing cost under a ToU tariff for an urban railroad system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.1
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• pp.48-52
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• 2011

Over the years, traditionally, six-switch three-phase inverters have been widely utilized for variable speed alternating current motor drives. Recently, some efforts have been made on the application of four-switch three phase inverter for uninterruptible power supply and variable speed drives. This is due to some advantages of the four-switch three phase inverter over the conventional six-switch three-phase inverters such as reduced price due to reduction in number of switches, reduced switching losses, reduced number of interface circuits to supply logic signals for the switches, simpler control algorithms to generate logic signals, less chances of destroying the switches due to lesser interaction among switches, and less real-time computational burden. However such as slow di/dt and speed limitation, are the inherent characteristics and main drawbacks of the four-switch configuration. Those problems can be overcome in conjugation with Voltage-doublers which has additional advantage, such as unity power factor correction.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.564-565
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• 2008

All over the world, energy environment dramatically changes because of highly oil price, global warming and reduction of greenhouse gas. The power sector is effected directly indirectly by these factors. Especially, the power expansion planning of power sector should adapt itself to new surroundings. This paper presents the new system of the power expansion planning that reflects Genco's needs, power market and variable conditions. This presented system would provide regulator and Gencos with useful information about a power planning.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.107-112
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• 1998

In this paper, we introduce the design method using CAE(Computer Aided Engineering) which is profitable in the compatibility and standardization of the developed product, and the reduction of construction time and price to develop and design a machine equipment. Particularly, we select the standard model to design or develop from the large machinery to the super precision one, extract the peculiar characters of the model by the close analysis on the physical and technical part, the experiment for the characteristics of objective dimensions by analogical mathematical analysis for previous results, and can induce the design model demanded by user investigating optimal data in the design previous. We present the analogical algorithms and process method of design factors and restriction factors in the systematization design with computer. Then we analyze step functions for each systematization equipment and induce the process of technical data with actuator model.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.2
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• pp.171-186
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• 1996

This paper comes from an observation that overemphasis on capacity utilization meausre, which is usual under capacity shortage, can seriously hurt the firm's profit and potential process improvement. We suggest a model that can be used in designing a coordination scheme for decentralized marketing and manufacturing activities. Using a price and time-sensitive demand and capacitated lotsizing model, we derive an effective communication medium betwen marketing and manufacturing. This Balance Indicator of process capacity and flexibility also implies that the increase in capacity availability and setup time reduction should be balanced by its market requirements. This is particularly important when a firm tries to improve its process capability by kaizen. Further, the model can be used to show the comparative performances of scheduling policies under capacity imbalnce. We show the shortening the scheduling cycle can improve the firm profit without changing the simple scheduling rule.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.851-856
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• 1996

In this paper, we introduce the design method using CAE(Computer Aided Engineering) which is profitable in the compatability and standardization of the developed product, and the reduction of construction time and price to develop and design a machine equipment. Particularly, we select the standard model to design or develop from the large machinery to the super precision one, extract the peculiar characters of the model by the close analysis of the physical and technical part, the experiment for the characteristics of objective dimensions by analogical mathematical analysis for previous results, and can induce the design model demanded by user investigating optimal data in the design previous We present the analogical algorithms and process method of design factors and restriction factors in the systematization design with computer. Then we analyze step functions for each systematization equipment and induce the process of technical data with actuator model.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.398-401
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• 2005

The characteristic of sheet metal process is the few loss of material during process, the short processing time and the excellent price and strength. Such press-forming process are the used machine ability and the characteristic, used material, the accuracy of the part which becomes processing and side condition of a process are considered and the designed. The purpose of this study is apply efficiently sheet metal forming processing by 3D formation-analyzed program simulations in the site. By a study, forming process was simulation to drawing and trimming and cam process using static-implicit method software. By making apply this to an industrial site the productivity improvement and cost reduction etc. effect able was predicted.

• Journal of Biosystems Engineering
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• v.40 no.2
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• pp.102-109
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• 2015

Purpose: Slow manual harvesting of rain-fed chickpeas cultivated in fallow fields in developing countries have encouraged the design of a mechanical harvester. Methods: A tractor-pulled harvester was built, in which a modified stripper header detached pods from an anchored plant and a chain conveyor transferred material. The stripper harvester was redesigned to use: 1) the maneuverability of tractor-mounted frames, 2) the adaptability of floating headers, and 3) the flexibility of pneumatic conveyors. Results: A mobile vacuum conveyor, which was an innovator open system, was designed for the dilute phase transferring mode for both grain and material other than grain. A centrifugal fan transferred harvested material to a cyclone separator that settled harvested material in a grain tank 1 m high. The machine at the spot work rate of $0.42ha{\cdot}h^{-1}$ harvested chickpea pods equal to the output of 16.6 farm laborers. Conclusion: The low cost and reasonable projected purchase price are the advantages of the concept. Additionally, the shattering loss reduction confirms the feasibility of the prototype chickpea harvester for commercialization.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.90-90
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• 2013

Since discovery, NdFeB permanent magnet has replaced application of the conventional magnets rapidly because of its superior physical and mechanical properties. With increasing consumption of power combined with energy resource depletion, energy efficiency is becoming more and more inportant. According to recent reports, almost almost half of the electric power is consumed by motor, and NdFeB magnets which are the core component of the motor play a key role on improving energy efficiency of the devices. In parallel with finding alternatives energy resources, research works improving energy efficiecy have been conducted world wide. Althogh NdFeB magnets usage have been expanded to various applications, key materials such as Nd and Dy, resouces lean heavily on specific area, China. Magnetic industry revently experienced skyrocketing price fluctuatioin of rare earth at around 2008. Chineses government's regulations worsened the situation and arose a necessity to develop methods to minimize rare earth use. In this presentation, POSCO's recent research works on rare earth reduction is presented including novel powder alloying method using nitrate precursors. Also, future R&D plans for rare earth free magnets is briefly introduced as well.

• Journal of the Korean Society for Railway
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• v.9 no.2 s.31
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• pp.19-24
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• 2006

Green gas emissions Trading System(ETS) came into effect in the Europe last year 2005. All transport modes have tried to reduce green gas emission and EU member countries are promoting the use of environmental friendly transport mode to avoid economic loss due to green gas emission. Besides ETS, rapidly rising of oil price and peak oil urge to invest more in the environmental friendly public transport mode and to discourage the use of private cars. The operation of KTX is estimated to bring external cost reduction up to 570 bil. won in 2004 based on European external unit costs of transport modes. This result implies that the expansion of high speed rail network and reconsideration of East-West high speed rail network which is not considered because of weak economic validity is required.