• ETRI Journal
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• 제37권1호
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• pp.11-20
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• 2015

This paper deals with optimal power allocation for channel estimation of orthogonal frequency-division multiplexing uplinks in time-varying channels. In the existing literature, the estimation of time-varying channel response in an uplink environment can be accomplished by estimating the corresponding channel parameters. Accordingly, the optimal power allocation studied in the literature has been in terms of minimizing the mean square error of the channel estimation. However, the final goal for channel estimation is to enable the application of coherent detection, which usually means high spectral efficiency. Therefore, it is more meaningful to optimize the power allocation in terms of capacity. In this paper, we investigate capacity with imperfect channel estimation. By exploiting the derived capacity expression, an optimal power allocation strategy is developed. With this developed power allocation strategy, improved performance can be observed, as demonstrated by the numerical results.

• 대한산업공학회지
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• 제25권2호
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• pp.274-281
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• 1999

In this paper, we determine the required storage capacity of a unit-load automated storage/retrieval system(AS/RS) under random storage assignment(RAN) and n-class turnover-based storage assignment(CN) policies. For each of the storage policies, an analytic model to determine the optimal storage capacity of the AS/RS is formulated so that the total cost related to storage space and space shortage is minimized while satisfying a desired service level. A closed form of optimal solutions for the RAN policy is derived from the model. For the CN policy, an optimal storage capacity is shown to be determined by applying the existing iterative search algorithm developed for the full turnover-based storage(FULL) policy. Finally, an application of the approach to the standard economic-order-quantity inventory model is provided.

• KIEAE Journal
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• 제10권2호
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• pp.19-24
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• 2010

According to the increasing demands of supercomputer, an exclusive supercomputer building is requested to install a supercomputer for promoting high-end R&D as well as creating the public service infrastructure in the national level. KISTI, as a public supercomputer center with the 4th supercomputer (capacity of 360Tflops), is experiencing shortage of infrastructure systems, caused by increased capacity. Thus, it is anticipated that the situation will be growing serious when the 5th and 6th supercomputers will be installed. On this study, analyzed on the 5th supercomputer system through projecting performance level and optimal operating environments by assessing infra-capacity. Explored way to construct optimal operating environments through infrastructure-capacity analysis of supercomputer center. This study can be of use for reviewing KISTI's conditions as the only supercomputer center in Korea. In addition, it provides reference data for planning the new exclusive supercomputer center in terms of feasibility, while analyzing infrastructure systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.186-188
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• 2005

This paper presents a method of finding the optimal capacity of renewable energy in power system to prepare Kyoto-protocol. In order to determine the capacity of renewable energy, this paper finds a amount of CO2 emission and capacity of power reduction for each energy type. The proposed method performs economic dispatch including the existing facilities, renewable energy and Emission trading, and finds optimal capacity of renewable energy Power satisfying minimum total cost. Finally, the proposed idea is demonstrated with a case study.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1405-1407
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• 2000

This paper is on optimal design for DC substation capacity for Mass Transit System. Three factors are considered for the design i.e. substation arrangements, line configuration and substation power capacity. In this study, we discussed substation power capacity only. At first, DC-fed-traction system is introduced on an outline, a characteristics of train and fed network. Optimal design procedures is described, and modelling for DC-fed-traction system are presented. The circuit-solution method is presented by matrix formula. In order to simulate DC substation power capacity more closely to actual situations, we proposed the program.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.398-401
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• 2000

This paper describes the design of optimal location and capacity of DC substation for Mass Transit System. Three factors are considered for the design i.e. substation arrangements, line configuration and substation power capacity. In this study, we considered all of them for capacity calculation of power supply system for MTS. At first, DC-fed-traction system is introduced on an outline, a characteristics of train and fed network, and design method of substation arrangements. Optimal design procedures are described, and program for capacity calculation of the system is presented. In addition, the computer simulated results are compared with the conventional simple calculation method.

• 산업공학
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• 제16권2호
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• pp.195-200
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• 2003

In this paper, the selective use of RTS and CTS frames is considered to analyze the capacity of IEEE 802.11 WLAN (Wireless Local Area Network). The RTS and CTS frames are used to transmit the data frames longer than dot11RTSThreshold according to IEEE 802.11 specification. The analysis of the optimal RTS-CTS threshold is derived to maximize the capacity of IEEE 802.11 WLAN. And, numerical examples are also presented for IEEE 802.11 a and b WLANs.

• 전기학회논문지
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• 제64권2호
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• pp.208-213
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• 2015

This study presents the estimation method for the optimal capacity of BESS(Battery Energy Storage System) in order to reduce the electric charges of common consumer. The daily optimal charge and discharge plan of BESS which satisfies the given constraints is established using linear programming through the change of rated output/rated capacity of the time that shows the electric charges in the highest reduced rate has been selected. There will be a problem to compare only reduced rate because the bigger the rated capacity, the more reduced rate is increased. Therefore, rated output/rated capacity of the time when the reduced amount of electric charges for a year is higher than the investment cost of BESS was selected.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1163-1170
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• 2014

Due to global environmental regulations and policies with rapid advancement of renewable energy technologies, the development type of renewable energy sources (RES) in power systems is expanding from small-scale distributed generation to large-scale grid-connected systems. In the near future, it is expected that RES achieves grid parity which means the equilibrium point where the power cost of RES is equal to the power costs of conventional generators. However, although RES would achieve the grid parity, the cost related with development of large-scale RES is still a big burden. Furthermore, it is hard to determine a suitable capacity of RES because of their output characteristics affected by locations and weather effects. Therefore, to determine an optimal capacity for RES becomes an important decision-making problem. This study proposes a method for determining an optimal installed capacity of RES from the business viewpoint of an independent power plant (IPP). In order to verify the proposed method, we have performed case studies on real power system in Incheon and Shiheung areas, South Korea.

• 한국항해학회지
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• 제15권3호
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• pp.13-24
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• 1991

This paper aims to determining the optimal capacity of Pusan port in view point of Container Physical Distribution cost. It has been established a coast model of the container physical distribution system in Pusan port is composed of 4 sub-systems and in-land transport system. Cargo handling system, transfer & storage system and in-land transport system, and analyzed the cost model of the system. From this analysis, we found that the system had 7 routes including in-land transport by rail or road and coastal transport by feeder ship between Pusan port and cargo owner's door. Though railway transport cost was relatively cheap, but, it was limited to choose railway transport routes due to the introducing of transport cargo allocation practice caused by shortage of railway transport capacity. The physical distribution ost for total import & export container through Pusan port was composed of 4.47% in port entring cost, 12.98% in cargo handling cost, 7.44% in transfer & storage cost and 75.11% in in-land transport cost. Investigation in case of BCTOC verified the results as follows. 1) The optimal level of one time cargo handling was verified 236VAN (377TEU) and annual optimal handling capacity was calculated in 516, 840VAN(826, 944TEU) where berth occupancy is $\rho$=0.6 when regardless of port congestion cost, 2) The optimal level of one time cargo handling was verified 252VAN (403TEU) and annual optimal handling capacity was calculated in 502, 110VAN (803, 376TEU) where berth occupancy is $\rho$=0.58 when considering of port congestion cost.