• ETRI Journal
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• 제25권4호
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• pp.211-218
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• 2003

This paper presents a dynamic resource allocation algorithm with multi-frequency time-division multiple access for the return link of interactive satellite multimedia networks such as digital video broadcasting return channel via satellite systems. The proposed timeslot assignment algorithm, called the very efficient dynamic timeslot assignment (VEDTA) algorithm, gives an optimal assignment plan within a very short period. The optimality and computational efficiency of this algorithm demonstrate that it will be useful in field applications.

• Geomechanics and Engineering
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• 제20권4호
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• pp.313-322
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• 2020

This study focuses on a prediction approach of compaction compensation grouting efficiency in sandy soil. Based on Darcy's law, assuming that the grouting volume is equal to the volume of the compressed soil, a two-dimensional calculation model of the compaction compensation grouting efficiency was improved to three-dimensional, which established a dynamic relationship between the radius of the grout body and the grouting time. The effectiveness of this approach was verified by finite element analysis. The calculation results show that the grouting efficiency decreases with time and tends to be stable. Meanwhile, it also indicates that the decrease of grouting efficiency mainly occurs in the process of grouting and will continue to decline in a short time after the completion of grouting. The prediction three-dimensional model proposed in this paper effectively complements the dynamic relationship between grouting compaction radius and grouting time, which can more accurately evaluate the grouting efficiency. It is practically significant to ensure construction safety, control grouting process, and reduce the settlement induced by tunnel excavation.

• The Journal of the Korea Contents Association
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• 제8권5호
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• pp.192-206
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• 2008

With many changes such as the increase in telemarketing, internet marketing and enforcement of bancassurance, the Korean life insurance companies have undergone a startling transformation. The purpose of this paper is to measure and analyse the static/dynamic efficiency of Korean life insurance companies employing Data Envelopment Analysis(DEA). As the result of the static efficiency analysis, we provide CCR, BCC and scale efficiency, return to scale, and reference set of Korean life insurance companies in 2004. And we also describe about the trend and stability of their efficiency for 7 years(1998-2004) in the dynamic efficiency analysis.

• ETRI Journal
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• 제30권4호
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• pp.587-596
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• 2008

Facility-based competition (FBC) in the telecommunications market is considered to have lower static efficiency in the short term and higher dynamic efficiency in the long term. Under service-based competition (SBC), the entrant can reduce its setup costs by leasing network facilities from the incumbent, which makes the entrant viable, pushes the market price down and promotes static efficiency. This paper attempts to measure static efficiency by comparing the profits of the incumbent and entrant in terms of consumer surplus and social welfare under each competition type by extending the Stackelberg model. The results, assuming a linear demand function and variation in regulatory level, show that FBC results in higher social welfare than SBC on the whole. However, SBC accompanied by strong regulation is also shown to have the potential to be superior over FBC. It is also revealed that FBC exhibits a higher producer surplus (particularly, the incumbent's producer surplus) and is, therefore, more desirable in terms of dynamic efficiency. When the entrant's cost is high in FBC, social welfare is shown to be lowered, implying that cost competitiveness is a necessary condition for social welfare.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제21권8호
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• pp.851-856
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• 2010

This paper presents an efficiency enhancement for the balanced power amplifier using DBS(Dynamic Bias Switching) method which dynamically provides the power amplifier with two bias voltage levels according to the input envelope signal. In order to apply the dynamic biases to each side of the balanced power amplifier, two switching stages are adopted. Using an OFDM signal with a bandwidth of 20 MHz and a PAR(Peak to Average Ratio) of 8.5 dB, 6 % of PAE(Power-Added Efficiency) is improved at an output power of 42.5 dBm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.749-761
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• 2014

Improving spectrum utilization efficiency is a fundamental goal of dynamic spectrum access technology. The definition of spectrum holes determines how to detect and exploit them. Current definitions of spectrum holes are ineffective in exploiting spatial-temporal spectrum holes. In this paper, a novel definition of spectrum holes is proposed, in which throughput loss indicates the impact of secondary users on primary users. The definition specifies spectrum holes, unifies the impact of secondary users on primary users and is effective exploiting spatial-temporal spectrum holes. Theoretical analysis and numerical simulations show that the new definition proposed in this paper significantly improves the spectrum utilization efficiency.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권1호
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• pp.1-7
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• 2009

This paper describes design of high energy efficiency 32 bit parallel processor core using instruction-levels data gating and dynamic voltage scaling (DVS) techniques. We present instruction-levels data gating technique. We can control activation and switching activity of the function units in the proposed data technique. We present instruction-levels DVS technique without using DC-DC converter and voltage scheduler controlled by the operation system. We can control powers of the function units in the proposed DVS technique. The proposed instruction-levels DVS technique has the simple architecture than complicated DVS which is DC-DC converter and voltage scheduler controlled by the operation system and a hardware implementation is very easy. But, the energy efficiency of the proposed instruction-levels DVS technique having dual-power supply is similar to the complicated DVS which is DC-DC converter and voltage scheduler controlled by the operation system. We simulate the circuit simulation for running test program using Spectra. We selected reduced power supply to 0.667 times of the supplied power supply. The energy efficiency of the proposed 32 bit parallel processor core using instruction-levels data gating and DVS techniques can improve about 88.4% than that of the 32 bit parallel processor core without using those. The designed high energy efficiency 32 bit parallel processor core can utilize as the coprocessor processing massive data at high speed.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제60권9호
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• pp.1674-1683
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• 2011

More than 80% of electric loads need DC electricity rather than AC at the moment. If DC power could be supplied directly to the terminal loads, power conversion stages including rectifiers, converters, and power adapters can be reduced or simplified. Therefore, DC microgrids may be able to improve energy efficiency of power distribution systems. In addition, DC microgrids can increase the penetration level of renewable energy resources because many renewable energy resources such as solar photovoltaic(PV) generators, fuel cells, and batteries generate electric power in the form of DC power. The integration of the DC generators to AC electric power systems requires the power conversion circuits that may cause additional energy loss. This paper discusses the capability and feasibility of DC microgrids with regard to energy efficiency analysis through detailed dynamic simulation of DC and AC microgrids. The dynamic simulation models of DC and AC microgrids based on the Microgrid Test System in KEPCO Research Institute are described in detail. Through simulation studies on various conditions, this paper compares the energy efficiency and advantages of DC and AC microgrids.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.19-20
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• 2014

Boiler design should be desinged to maximize thermal efficiency of the system under imposed load requirement and a boiler should be validated for transient operation. If a proper prediction is possible on the transient behavior and transient characteristics of a boiler, one may asses the performance of boiler component, control logics and operation procedures. In this work, dynamic modeling method of boiler is presented and dynamic simulation of load runback scenario was carried out on suprecritical oil-firing boiler.

• Journal of Digital Convergence
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• 제10권2호
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• pp.63-71
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• 2012

This paper investigates efficiency analysis to IT HRD programs in the dynamic perspective. First, empirical result shows that government fund of IT research center is significantly associated with SCI thesis and the more trial goods and SW development is connected with the more patent and technology transfer. Second, ITRC program has been operated efficiently since 2000. Finally, dynamic efficiency analysis implicates that ITRC program is more efficient than other IT SoC program and foreign student support program. The reason why ITRC program is more efficient is generated not from the effect of imitation by catch-up strategy to developed HRD programs, but new operation system introducing and utilizing HRD performance system.