• 경영과학
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• 제27권2호
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• pp.21-29
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• 2010

We consider an economic approach for spectrum operations in mobile networks. We present the investment function of base stations according to the number of FAs assuming the linearity of cell splitting. We show that there is an economic amount of spectrum which corresponds to the optimal number of FAs that minimizes the investment. We analyze the impact of the cost structure and the traffic distribution in base stations on the economic amount of spectrum. This paper is applicable to an economic spectrum operation for mobile operators. In addition, the national regulatory authority can use the economic amount of spectrum as the minimal amount for spectrum allocation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.520-522
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• 1998

A development and application of machine vision system is introduced, which automatically recognizes the serial number of nuclear fuel tube. For the recognition, a indirect back light illuminating system is designed and a pattern matching algorithm based on neural network is applied. The various operation and management functions are also developed, on a PC under windows OS, for easy operation and data management, respectively. By the successful application of the vision system the productivity of the nuclear fuel tube recognition process is highly improved.

• 한국항공운항학회지
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• 제28권2호
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• pp.29-35
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• 2020

In this paper, we established a prediction model of fuel consumption at the aircraft's taxi operation. To look for countermeasures to reduce fuel consumption and carbon emissions, Airbus A380's actual ground taxi data was used. As a result, the number of stops or turnings during the taxi operation was not related to fuel consumption. It was confirmed that the amount of fuel consumption in the taxi operation was the taxi time and the thrust change. It can be confirmed that ground control optimization, which is the result of close cooperation between the control organization and the airline, is absolutely necessary to reduce taxi time and minimize the occurrence of thrust change events.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1449-1458
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• 2006

Controlled Auto-ignition (CAI) combustion processes can be broadly divided between a CAI process that is applied to four-cycle engines and a CAI process that is applied to two-cycle engines. The former process is generally referred to as Homogeneous Charge Compression Ignition (HCCI) combustion and the later process as Active Thermo-Atmosphere Combustion (ATAC) The region of stable engine operation differs greatly between these two processes, and it is thought that the elucidation of their differences and similarities could provide useful information for expanding the operation region of HCCI combustion. In this research, the same two-cycle engine was operated under both the ATAC and HCCI combustion processes to compare their respective combustion characteristics. The results indicated that the ignition timing was less likely to change in the ATAC process in relation to changes in the fuel octane number than it was in the HCCI combustion process.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 연구회 합동 학술발표회 논문집
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• pp.39-43
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• 1998

A large number of soft switching topologies included a resonant circuit have been proposed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this paper, the authors propose power conversion system, DC-AC inverter of high efficiency and high power factor with soft switching mode by partial resonant method. The switching devices in a proposed circuits are operated with soft switching by the partial resonant method, that is, PRS2MPC (Partial Resonant Soft Switching Mode Power Converter). The result is that the switching loss is very low and the efficiency of system is high. And the snubber condenser used in partial resonant circuit makes charging energy regenerated at input power source for resonant operation.

• 한국정밀공학회지
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• 제9권3호
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• pp.122-131
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• 1992

In this paper an approximate solution method for the large-scale Traveling Salesman Problem (TSP) is presented. The method starts with the subdivision of the problem domain into a number of cluster by considering their geometric characteristic. Each cluster has a limited number of nodes so as to get a local solution. They are linked go give the least pathe which covers the whole domain and become TSPs solution with start-and end-node. The approximate local solution in each cluster are obtained based on geometrical properties of the cluster, and combined to give an overall approximate solution for the larte-scale TSP.

• 한국경영과학회지
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• 제31권3호
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• pp.1-10
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• 2006

In this paper we deal with a cell planning issue arisen in a CDMA based multicast network. In a CDMA based wireless network, a terminal can significantly reduce the bit error rate via the cohesion of data streams from multiple base stations. In this case, multiple base stations have to be operated according to a common time line. The cells whose base stations are operated as such are called soft-combined cells. Therefore, a terminal can take advantage of error rate reduction, if the terminal is in a soft-combined cell and at least one neighboring cell is also soft-combined. However, as soft-combining operation gives heavy burden to the network controller, the limited number of cells can be soft-combined. Our problem us to find a limited number of soft-combined cells such that the benefit of the soft-combining operation is maximized.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1504-1506
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• 2004

The platform screen door(PSD) hasn't been installed yet within the manual operation system, that is, ATS & ATC Signal system. In other countries, it is mostly installed and operated within automatic operation system, that is, ATO. Especially, as a part of the environment friendly system installation, the installation of PSD shall be considered aggressively to improve the air quality in the underground area and to maintain the air-conditioning. Besides the number of suicides in the subway station gets increased these days causing safety hazard, so the installation of PSD is positively reviewed. To install PSD in the manual operation system, it is important to stop the train at the correct position. So we would like to suggest the technical system thereby.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1178-1187
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• 2008

According to the operation data between $2007{\sim}2008$(January$\sim$June) for essential safety equipment including ATC, there were nothing special but stable and steady. And also emergency stop number of count are decreasing. But the frequency are still above the resonable count and it means driving condition should be improved through interface between ground and locomotive same as come to an understanding with driver. The number of count of emergency stop for VACMA(vigilance system) are also decreasing but also the frequency are above resonable count. This phenomenon caused by careless driving for the driver or the system malfunction. So the continuous monitoring for the data is necessary.

• 한국수학교육학회지시리즈A:수학교육
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• 제45권1호
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• pp.61-74
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• 2006

The ability of understanding the number and number systems, grasping the properties of number systems, and manipulating number systems is the foundation to understand algebra. It is useful to deepen students' mathematical understanding of number systems and operations. The authentic understanding of numbers and operations can make it possible for the students to manipulate algebraic symbols, to represent relationship among sets of numbers, and to use variables to investigate the properties of sets of numbers. The high school students need to understand the number systems from more abstract perspective. The purpose of this study is to study on understanding and application ability of eleventh graders of basic properties of operations with real numbers.