• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.237-243
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• 2010

A wireless power transfer system based on magnetically coupled two resonators is analysed using the filter theory. Design equations for each lumped parameter circuit components are derived. As a result, change of coupling coefficient between the resonators and/or change of load resistance are easily responded. Effect of circuit loss to the design theory is also addressed. After designing a power transfer system, a real system is constructed using spiral and loop coils. Dependence of circuit elements on their dimensions is measured in advance and used to cope with the designed element values. Simulated response by use of designed element values and measured result are compared, indicating the validity of the theory.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.353-359
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• 2014

Recently, the use of mobile devices has increased, and mobile traffic is growing rapidly. In order to deal with such massive traffic, cognitive radio (CR) is applied to efficiently use limited-spectrum resources. However, there can be multiple communication systems trying to access the white space (unused spectrum), and inevitable interference may occur to cause mutual performance degradation. Therefore, understanding the effects of interference in CR-based systems is crucial to meaningful operations of these systems. In this paper, we consider a long-term evolution (LTE) system using additional spectra by accessing the TV white space, where low-power devices (LPDs) are licensed primary users, in addition to TV broadcasting service providers. We model such a heterogeneous system to analyze the co-existence problem and evaluate the interference effects of LPDs on LTE user equipment (UE) throughput. We then present methods to mitigate the interference effects of LPDs by 'de-selecting' some of the UEs to effectively increase the overall sector throughput of the CR-based LTE system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.3
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• pp.78-84
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• 2002

This research is basically deals with an inventory distribution system with several regional sides branches. Under the continuous review policy, each sales branch places an order to its supplier whenever on hand plus on order inventory falls on the order point, and the order quantity is received after elapsing a certain lead time. This research first shows the method how to apply the product with low lever of demand into the continuous review policy. For the application, we use an order level as the maximum level of inventory during an order cycle. Also we analyze the lost sales case as a customer behavior. Further we use variable demands and variable lead times for more realistic situation. Based on the above circumstances, the research mainly discusses those methods to decide the optimal order level, order point, and order quantity for each sales branch which guarantees the system wide goal level of service, while keeping the minimum level of the system wide total inventory.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.145-150
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• 2003

The national subway went under construction in 1971, and after three years of endeavor, Seoul subway line number one opened for traffic in 1974. Line number two went under construction in 1978 and it opened for traffic in 1984. With the use of safety operation for more than 20 years, the life cycle nearly came to an end. Therefore the improvements for the safety operation are unavoidable. The total system should not be affected when the new and conventional systems are overlapped, the system operation is in the initial stage, and it confronts the situation of abnormal operation. However, there is a total lack of experience in construction and improvement for the trains that are in the use of large transport and density headway. In this paper, we propose an improvement method of the subway signalling system using ATO (Automatic Train Operation control scheme) to which the latest Digital ATC is applied, and examine the first application model of ATO system.

• Journal of Fashion Business
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• v.15 no.6
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• pp.101-112
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• 2011

Three-dimensional(3D) virtual clothing simulation system may require the use of physical, mechanical, and configurational data in order to mimic the actual clothing with high degree of realism. Therefore the 3-dimensional scanning system based on optical methods was adopted to extract the 3-dimensional data of the fabric surface. In this study, the appearances of the 3-dimensionally transformed textile fabrics via several finishing procedures were investigated using a 3D scanning system. The wool gauze fabrics treated with the shrink-proof finishing and the felting process showed height changes up to 4.5mm. The 3-dimensional configuration may be objectively described by the use of mesh generation from the scanned output. The generated mesh information may further be utilized in the 3D virtual clothing simulation system for accurate description of the fashionable textile materials used in the simulation system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.307-310
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• 2011

In this paper we use general centrifugal pump instead of screw pump in alternative Energy system. This alternative Energy system with screw pump compared the volume flour of water pumping and efficiency. Screw pump is designed that it rotated without a toque in another Shaft. Futhermore it have noise and abrasion, The pump used in high pressure with fast rotate.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.4
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• pp.165-171
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• 2005

Electromagnetic transient simulation can be used to model complex non-linearities that very difficult to represent adequately in the frequency domain. This problem is greatly reduced with the use of frequency dependent network equivalents for the linear part of the system. S-domain rational function fitting techniques for representing frequency dependent equivalents have been developed using Least Squares Fitting(LSF). However it does not suffer the implementation error that exited in this work as it ignored the instantaneous term. This paper presents the formulation for developing 2 port Frequency Dependent AC System Equivalent(FDACSE) with the instantaneous term in S-domain and illustrates its use. This 2 port FDNE have been applied to the New Zealand AC system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the 2 port (FDACSE) developed with Norton Equivalent network. The study results have indicated the robustness and accuracy of 2 port FDACSE for electromagnetic transient studies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.452-455
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• 2005

Today the tastes of consumers change rapidly and the kinds of the products become diverse. Therefore the product life cycle becomes shorter and shorter. Moreover the save of resources and the recycling for the environmental preservation are the essential theme. On this the necessary information for the product development increases enormously. For the right use of the information the design process should be supported by the proper design tool. For this the 'design catalogue system for recycling' is suggested here. This system consists of four parts, that is, 'the existing automobile system database', 'working principle database', 'assessment system of the ease of disassembly' and 'one's own product development database' By the use of this system the product development period could be reduced about 30% drastically.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.291-294
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• 2004

There are many position fixing systems in the world from ancient times. But the principles are to compare the position to want to know with the known position already. The position finding system which is not restricted by weather condition and/or electronic apparatus has been sought. The best system is the GPS as far. But the system has the fatal faults as follows; 1. to depend on satellite's accuracy, 2. not to use underwater. This paper is to investigate theoretically position fixing and north finding by using free gyroscope. This paper introduce a position fixing and north finding method by measuring inclination of 2 free gyroscopes. And this system does not depend on the weather condition and underwater condition. What is more, it could use on the planets, if the gravity exits.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.9
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• pp.7-16
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• 2019

According to KGS FS551, the safety of an exposure pipe system should be calculated quantitatively by calculating the stress of exposed piping for thermal expansion. However, many pipe system designs and installation sites are not equipped for this. Therefore, KGS FS551 suggested the use of safe gas by presenting the recommended pipe shape. The shapes of various pipe systems have been derived. However, the recommended shape could not be an absolute evaluation standard. Furthermore, the ongoing debate over standards between a plumbing installer and an inspector is an obstacle to the efficient and safe use of gas. Therefore, the correct pipe system evaluation method is examined in this study, and the safety of the existing exposed pipe system is verified.