• 한국통신학회논문지
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• 제25권6A호
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• pp.900-909
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• 2000

적응배열 안테나는 CDMA 이동통신 시스템의 용량을 증가시킬 수 있는 가장 유망한 기법 중의 하나이다. 본 논문에서는 각도 추정오차가 있는 경우 적응 배열 안테나를 사용한 비동기식 W-CDMA 시스템의 용량을 상향링크 및 하향링크에서 분석하였다. 결과로부터, 용량은 각도 추정 오차에 의하여 감소함을 알 수 있었다. 구체적으로, 9소자 적응배열 안테나에서 5도의 오차가 있는 경우 용량은 상향링크에서 5.2% 하향링크에서 11.6% 감소됨을 관찰할 수 있었다. 또한 본 논문에서는 환경이 다른 채널에서 용량의 비교도 수행하였다. 그러나 전력 제어로 인하여 라이스 지수의 증가가 거의 용량에 영향을 주지 않는다는 것을 알 수 있었다.

• 전력전자학회논문지
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• 제24권3호
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• pp.139-146
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• 2019

As the number of electric vehicles (EVs) in Jejudo Island increases, the secondary use of EV batteries is becoming increasingly mandatory not only in reducing greenhouse gas emissions but also in promoting resource conservation. For the secondary use of EV batteries, their capacity and performance at the end of automotive service should be evaluated properly. In this study, the battery state information from the on-board diagnostics or OBD2 port was acquired in real time while driving three distinct routes in Jejudo Island, and then the battery operating characteristics were assessed with the driving routes. The route with higher altitude led to higher current output, i.e., higher C-rate, which would reportedly deteriorate state of health (SOH) faster. In addition, the SOH obtained from the battery management system (BMS) of a 2017 Kia Soul EV with a mileage of 55,000 km was 100.2%, which was unexpectedly high. This finding was confirmed by the SOH estimation based on the ratio of the current integral to the change in state of charge. The SOH larger than 100% can be attributed to the rated capacity that was lower than the nominal capacity in EV application. Therefore, considering the driving environment and understanding the SOH estimation process will be beneficial and necessary in evaluating the capacity and performance of retired batteries for post-vehicle applications.

• 한국지반환경공학회 논문집
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• 제5권1호
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• pp.75-84
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• 2004

연약지반 개량공법의 하나인 쇄석기둥은 일반 연직배수공법에 주로 사용되는 모래재료 대신에 쇄석재료를 사용하며 배수 및 침하량 감소, 지지력 증대의 복합 효과에 의해 지반을 개량한다. 최근 들어 대규모 토목공사에 사용되는 건설재료로서 막대한 양이 소요되는 모래는 현재 수요는 급증하고 구득은 갈수록 어려워져 재료는 고갈상태에 이르고 있는 실정으로서 쇄석기둥공법의 적용이 더욱 늘어나고 있는 추세이다. 특히, 최근 들어 쇄석기둥의 지지력 보강효과를 이용하는 경향이 증가함에 따라 지지력 보강 예측이 중요한 관심사항으로 대두되었으나 아직까지 주변지반과 쇄석기둥 구조체의 상호 거동을 합리적으로 반영한 산정식이 제시되어있지 못한 상태이다. 따라서 본 연구에서는 연약지반상에 조성된 쇄석기둥에 의한 개량효과중 지지력 증대효과를 규명하기 위해 쇄석기둥의 지지력 거동을 수치해석적으로 시뮬레이션하였다. 이렇게 함으로써 쇄석기둥이 설치되는 원지반의 물성과 쇄석기둥의 물성을 반영하면서 하중-침하거동을 파악하고자 하였다. 수치해석 시뮬레이션에 의한 지지력 거동을 원지반조건, 쇄석기둥 조건별로 분석하여 쇄석기둥의 지지력 거동식을 제안하고 제안된 지지력 예측방법과 거동을 계측한 실측치와의 검증을 실시하였다.

• ETRI Journal
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• 제28권5호
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• pp.688-691
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• 2006

This letter addresses the superimposed pilot aided multiuser channel estimation for the uplinks of multi-input multi-output orthogonal frequency-division multiplexing systems. To mitigate the embedded-data effects on the performance of channel estimation, a novel combining algorithm is proposed. Optimal pilot symbols are developed with respect to the least square channel estimate's mean square error. The averaged sum-capacity lower bound is derived and simulated. Simulation results show that on a low signal-to-noise ratio regime, our proposed scheme achieves better performance and higher capacity than the conventional pilot aided approach.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.61-65
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• 2015

For effective distribution planning and operation, we need a reliable estimation of operation capacity. But it is difficult to ensure reliability due to the low accuracy of section load data, which is used as a basis in estimating the operation capacity. This paper discusses how to improve the accuracy of section load data by analyzing the existing method of estimating the section load, using statistical techniques to adjust the acquired data, and using the section load estimation algorithm to estimate the section load based on the adjusted data.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.73-80
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• 1997

• 한국조경학회지
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• 제15권2호
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• pp.79-90
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• 1987

This second consecutive research was connected to 7he previous first research with same title. The purpose of this research is to estimate the carrying capacity for the Seonjeong royal tomb and to propose its management planning. User's characteristics and relationship between user's density and vegetational environment were analized for the above objective. The result of this research shall be summarized as follows. 1. The site was damaged seriously by pupils and social groups'picnic activities concentrated in special periods of Friday and weekend during April and May. 2. Social-psychological carrying capacity estimation would be impossible due to lack of relationship between user's density and satisfaction. 3. Maximum user's density limits as a ecological carrying capacity was 1.4 persons per 100 square meters and modified optimum ecological carrying capacity was estimated as 1.0persons per 100 square meters. Maximum visitors as a optimum carrying capacity of the Seonjeong royal tomb area was estimated as 6,000 persons when supposing the proposed landuse planning. 4. To restore and preserve the tomb landscape as a traditional historic site, Seonjeong royal tomb shall be managed by three landuse areas ; protection and control area, natural picnic area and shaded picnic area. And the protection and control area include three sites ; natural reclamation site, natural preservation site and tomb landscape conservation site.

• 전기학회논문지
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• 제65권6호
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• pp.969-978
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• 2016

Around the world are increasing the demand for ESS. Currently, the domestic is expected to benefit by operating ESS. In the domestic, it is expected to benefit from operations of the installed ESS because of the introduction of ESS less capacity. However ESS capacity to the maximum profit occurs is unknown. ESS is different from the charge-discharge characteristics and the reserve to replace, depending on the application. Therefore, it should be established in accordance with the ESS optimal capacity according to the purpose used because it can maximize the quality and efficiency of the electric energy. To the ESS optimal capacity estimation by the purpose used, It should compare the investment cost caused by ESS facility installation and operation cost caused by operating ESS. In this paper, the operation mathematical model for estimating marginal operation costs established. In operation mathematical model, operating cost is considered fuel cost and no-load cost start-up cost. Because no-load cost and start-up cost are not related to cost and power plant output, there are expressed an integer variable costs as a step function.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1927-1934
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• 2018

In this paper, we studied the state of charge (SOC) estimation algorithm of a high-capacity lithium secondary battery for electric vehicles (EVs) considering temperature characteristics. Nonlinear characteristics of high-capacity lithium secondary batteries are represented by differential equations in the mathematical form and expressed by the state space equation through battery modeling to extract the characteristic parameters of the lithium secondary battery. Charging and discharging equipment were used to perform characteristic tests for the extraction of parameters of lithium secondary batteries at various temperatures. An extended Kalman filter (EKF) algorithm, a state observer, was used to estimate the state of the battery. The battery capacity and internal resistance of the high-capacity lithium secondary battery were investigated through battery modeling. The proposed modeling was applied to the battery pack for EVs to estimate the state of the battery. We confirmed the feasibility of the proposed study by comparing the estimated SOC values and the SOC values from the experiment. The proposed method using the EKF is expected to be highly applicable in estimating the state of the high-capacity rechargeable lithium battery pack for electric vehicles.

• 대한교통학회지
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• 제13권1호
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• pp.167-183
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• 1995

The objective of study is to evaluate highway capaicty estimation alternative and to develop capacity from statistical distribution of observed traffic flow. Speed-Volume relation is analyzed from vehicle's headway distribution eliminating the long headway by confidence intervals 99%, 95%, 90%. Capacity estimate alternatives were evaluated from 95% , 90%, 85% level of cummulative distribution of observed hourly traffic flow adjusted to confidence intervals. The result of investigation revealed that maximum hourly rate of flow is 2, 130pcu at confidence interval of 995, 2, 233pcu at 95%, 2, 315pcu at 90% respectively. Compared to the capacity of 2, 200pcu per hour per lane used in HCM and KHCM(Korea Highway Capacity Manual), capa챠y appears to correspond to confidence interval of 95%. Using the traffic flow rate at confidence interval of 95% the maximum hourly flow rate is 2, 187pcu at 95% of cummulative volume distribution, 2, 153pcu at 90%, 2, 215pcu at 85%. The study suggests that raional capacity esimation alternative is to take the 95% of cummulative distribution of observed hourly traffic flow at 95% confidence headway interval eliminating 5% long headway.(i.e. 95-95 rule)