• 전기학회논문지
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• 제66권11호
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• pp.1561-1567
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• 2017

This paper calculates the effective capacity of EES providing the primary frequency control service based on its contribution to the frequency response of the power system. The amount of governor response from conventional generators which can be replaced by the primary frequency control from EES keeping the frequency response of the power system is defined as the effective capacity. The proposed method for calculating the effective capacity of EES is verified through case studies employing Korean power system. Furthermore, the application of the effective capacity of EES to power system operation is also discussed.

• 대한건축학회논문집:구조계
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• 제34권2호
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• pp.49-56
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• 2018

The use of highly absorptive materials in cement-based materials is increasing for internal curing purpose. However, calculation of correct absorption capacity of such materials is not easy, which leads to change in the effective water-to-cement ratio of cement paste by either absorbing or releasing water. In this study, effective absorption capacity of a highly absorptive material was found using isothermal calorimetry. Moreover, the effect of specific surface area was investigated. It was found that the method was capable of finding effective water absorption capacity of activated carbon fiber. For the activated carbon fiber used in this research, the effect of specific surface area was negligible because the high BET surface area was due to micropores less than 1nm, which does not affect the rate of hydration curve. Thus, the effective absorption capacity of such materials can be found successfully using this method.

• Geomechanics and Engineering
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• 제5권5호
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• pp.447-462
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• 2013

An analysis model for predicting the tip bearing capacity of drilled shafts in cohesionless soils is improved in this study. The evaluation is based on large amounts of drilled shaft load test data. Assessment on the analysis model reveals a greater variation in two coefficients, namely, the overburden bearing capacity factor ($N_q$) and the bearing capacity modifier for soil rigidity (${\zeta}_{qr}$). These factors are modified from the back analysis of drilled shaft load test results. Different effective shaft depths and interpreted capacities at various loading stages (i.e., low, middle, and high) are adopted for the back calculation. Results show that the modified bearing capacity coefficients maintain their basic relationship with soil effective friction angle ($\bar{\phi}$), in which the $N_q$ increases and ${\zeta}_{qr}$ decreases as $\bar{\phi}$ increases. The suggested effective shaft depth is limited to 15B (B = shaft diameter) for the evaluation of effective overburden pressure. Specific design recommendations for the tip bearing capacity analysis of drilled shafts in cohesionless soils are given for engineering practice.

• Journal of Communications and Networks
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• 제15권5호
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• pp.476-485
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• 2013

In this paper, the effective capacity of a multiple-input multiple-output (MIMO) system in two different cases with receive antenna selection (RAS) and transmit antenna selection (TAS) schemes is investigated. A closed-form solution for the maximum constant arrival rate of this network with statistical delay quality of service (QoS) constraint is extracted in the quasi-static fading channel. This study is conducted in two different cases.When channel state information (CSI) is not available at the MIMO transmitter, implementation of TAS is difficult. Therefore, RAS scheme is employed and one antenna with the maximum instantaneous signal to noise ratio is chosen at the receiver. On the other hand, when CSI is available at the transmitter, TAS scheme is executed. In this case, one antenna is selected at the transmitter. Moreover, an optimal power-control policy is applied to the selected antenna and the effective capacity of the MIMO system is derived. Finally, this optimal power adaptation and the effective capacity are investigated in two asymptotic cases with the loose and strict QoS requirements. In particular, we show that in the TAS scheme with the loose QoS restriction, the effective capacity converges to the ergodic capacity. Then, an exact closed-form solution is obtained for the ergodic capacity of the channel here.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권4호
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• pp.632-650
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• 2013

The paper considers a spectrum sharing cognitive radio (CR) network coexisting with a primary network under the average interference power constraint. In particular, the secondary user (SU) is assumed to carry delay-sensitive services and thus shall satisfy a given delay quality-of-service (QoS) constraint. The secondary receiver is also assumed to be equipped with multiple antennas to perform maximal ratio combining (MRC) to enhance SU performance. We investigate the effective capacity of the SU with MRC diversity under aforementioned constraints in Nakagami fading environments. Particularly, we derive the optimal power allocation to achieve the maximum effective capacity of the SU, and further derive the effective capacity in closed-form. In addition, we further obtain the closed-form expressions for the effective capacities under three widely used power and rate adaptive transmission schemes, namely, optimal simultaneous power and rate adaptation (opra), truncated channel inversion with fixed rate (tifr) and channel inversion with fixed rate without truncation (cifr). Numerical results supported by simulations are presented to consolidate our studies. The impacts on the effective capacity of various system parameters such as the number of antennas, the average interference power constraint and the delay QoS constraint are investigated in detail. It is shown that MRC diversity can significantly improve the effective capacity of the SU especially for cifr transmission scheme.

• 한국태양에너지학회 논문집
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• 제37권5호
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• pp.13-26
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• 2017

Solar power is expected to account for a considerable proportion of domestic renewable energy compared to other renewable energy sources. In this study, capacity credits, which are the most important factors for evaluating the effective capacity of photovoltaic power, are estimated by capacity factor-based approximation method. To do this, we use the data of solar power generation and capacity over many years and calculate the capacity factors of the domestic solar power. The results of the existing methods and ours proposed in this paper are compared and analyzed.

• 한국통신학회논문지
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• 제33권10B호
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• pp.928-938
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• 2008

인터넷 전화와 같이 품질 보장을 요구하는 서비스가 널리 보급되고 있으나 대부분의 인터넷 백본 네트워크는 이들을 최선형 서비스와 구별할 수 없다. 따라서 백본 네트워크가 품질 보장형 서비스의 품질조건을 충족시키면서 수용할 수 있는 최대 트래픽 량인 유효 용량을 파악하는 것은 인터넷 서비스 제공자 입장에서 매우 중요하다. 본 논문에서는 인터넷 백본 네트워크의 유효 용량을 평가할 수 있는 ns-2 기반 테스트-베드를 제안한 후 이를 이용하여 인터넷 전화 품질 기준 측면에서 실험 백본 네트워크의 유효 용량을 평가한다. 평가결과 실험 백본 네트워크의 유효 용량은 최대지연 보장 확률에 따라 물리적 용량의 $12%\;{\sim}\;55%$로 추정되었으며, 인가되는 트래픽의 유형과 인터넷 전화 품질 기준에 큰 영향을 받음을 알 수 있었다. 특히 백본 네트워크의 유효 용량을 높이기 위해서 인터넷 전화의 단대단 최대 지연시간의 보장 확률을 낮출 필요가 있음을 보였다.

• 대한한의학방제학회지
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• 제21권2호
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• pp.165-172
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• 2013

Objectives : This experiment was performed in order to study the effect of Maekmundong-tang on dyspnea patients. Methods : This study involved 14 dyspnea patients from March 1, 2012 to May 31, 2012. Lung capacity of the patients is evaluated with Peak flow meter. Results : Maekmundong-tang administration was revealed effect on dyspnea patients' lung capacity. Conclusions : It was found that Maekmundong-tang administration was effective on dyspnea patients' lung capacity. The mean degree of improvement was 21.79(L/min). It was shown that the more mild dyspnea level was, the more effective and short-term administration more effective.

• 전자공학회논문지A
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• 제33A권10호
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• pp.40-47
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• 1996

A method for computing effectiv ebandwidth of aggregated varable bit rate (VBR) moving picture experts group (MPEG) video traffic is proposed. To compute statistical characteristics of aggregated MPEG traffic, first we split input MPEG traffic into I, B, and P frame traffics and aggregate respective I, B, and P frame traffics according to the frame type. Second statisticsal characteristics of the aggregated MPEG traffic are obtained using those of aggregated I, B, and P frame traffics. The effective bandwidth of the aggregated I frame traffic is computed by using the gaussian bound. Using the modified equivalent capacity, we obtain the effective bandwidths of aggregated B and P frame traffics and then compute the effective bandwidth of the combined B and P frame traffic. Finally the effective bandwidth of the aggregated MPEG traffic is computed by adding the gaussian bound of the aggregated I frame traffic and modifed equivalent capacity of combined B and P frame traffic. Computer simulation shows that the proposed method estimates effective bandwidth of the aggregated MPEG traffic well.

• 한국태양에너지학회 논문집
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• 제39권4호
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• pp.79-91
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• 2019

The capacity credit (CC) is a key metric for mid- to long-term power system capacity planning. The purpose of this study is to estimate the CCs of domestic wind turbines. Based on hourly capacity factor (CF) data during the seven years from 2011 to 2017, the new so-called probabilistic CF scheme is introduced to effectively reflect the variability of CFs on CC estimation. The CCs are then estimated through the CF-based method and the ELCC (Effective Load Carrying Capability) method reflecting the probabilistic CF scheme, and the results are compared. The results show that the CC value 0.019 for domestic wind turbines proposed in the $8^{th}$ Basic Plan for Electricity Supply and Demand corresponds to the CC with a confidence level slightly lower than 95%.