• 상하수도학회지
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• 제22권1호
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• pp.3-14
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• 2008

ASM No. 2(Activated sludge model No. 2) is very useful model to analyze the wastewater treatment which removes nitrogen and phosphorus. But, it is difficult to apply ASM No. 2 to control of wastewater treatment since it has 17 material divisions and 46 parameters. So the purpose of this study was the simplification of ASM No. 2 and the provement of simplification model. Firstly ASM No. 2 was simplified with 5 material division and three phases(Anaerobic, aerobic, anoxic phases). The simplified model was proved by R-square using track study data. As a result of provement, the values of R-square in ${NH_4}^+$ were 0.9815 in ASM No. 2 and 0.9250 in simplified model and in ${NO_3}^-$ were 0.8679 in ASM No. 2 and 0.7914 in simplified model and in ${PO_4}^{3-}$ are 0.9745 in ASM No. 2 and 0.9187 in the simplified model when the ability to express the material variation was compared by R-square. So, the simplified model has enough ability to express the variation of ${NH_4}^+$, ${NO_3}^-$ and ${PO_4}^{3-}$.

• 한국수자원학회논문집
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• 제33권2호
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• pp.145-157
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• 2000

본 연구에서는 금강 대청댐하류의 본류구간에서 갈수시간에 대해서 WASP5모형 중에서 수질모의 부분인 EUTRO5모형과 1차원 정상류 수리모형인 HEC-2모형을 연계한 수질모형을 이용하여 대청조정지댐으로부터 강경수위표 지점까지 수질의 변화를 모의하였다. 수질 및 유량자료의 수집을 위하여 대청댐으로부터 금강하류에 위치한 주요 수위표지점에서 1998년 12월, 1999년 1월과 3월의 3회에 걸쳐 관측하였다. 수질모의모형은 1999년 1월 자료를 이용하여 보정되어지고, 1998년 12월자료와 1999년 3월자료를 이용하여 검증되어졌다. 모형에 의해서 모의된 수질변수들의 거리에 따른 변화는 1999년 3월자료를 이용하여 모의된 chlorophyll-a, BOD5, NH3-N, PO4-P와 같은 수질변수를 제외하고는 관측된 수질변수값과 거의 일치하였다. 또한 NH3-N과 PO4-P가 증가 혹은 감소되어 갑천과 미호천으로부터 금강본류로 유입된다고 가정하는 경우에 금강본류에서의 chlorophyII-a의 농도를 모의하였다. 모의한 바에 의하면 갑천과 미호천에서 NH3-N과 PO4-P가 70% 감소되어져 금강본류로 유입된다고 가정하는 경우를 제외하고는 거의 미미한 chlorophyII-a 농도변화율을 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.126-127
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• 2017

An accurate State Of Charge (SOC) estimation of battery is the most important technique for Electric Vehicles (EVs) and Energy Storage Systems (ESSs). In this paper a new integrated Unscented Kalman Filter-Particle Filter (UKF-PF) is employed to estimate the SOC of a $LiFePO_4$ battery cell and a significant improvement is obtained as compared to the other methods. The parameters of the battery is modeled by the second order Auto Regressive eXogenous (ARX) model and estimated by using Recursive Least Square (RLS) method to calculate value of each element in the model. The proposed algorithm is established by combining a parameter identification technique using RLS method with ARX model and an SOC estimation technique using UKF-PF.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2005년도 학술발표대회 논문집
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• pp.357-376
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• 2005

• 한국항해학회지
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• 제13권1호
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• pp.63-75
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• 1989

A two dimensional numerical model as well as theoretical formula are used to investigate the seich characteristics of Mok-po harbour. The natural periods of the first two modes computed from the numerical mode are about 34 minutes and 12 minutes which are well consistent with those by the theoretical formula.

• 유기물자원화
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• 제23권3호
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• pp.60-67
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• 2015

본 연구의 목적은 농경지에서 유출되는 유거수로부터 부영양화를 감소시키기 위하여 참나무를 원료로 제조한 바이오차의 인산염 인($PO_4-P$) 흡착특성을 구명하는 것이었다. 30 mg/L $PO_4-P$ 용액에 참나무 바이오차 투입량을 4~20 g/L로 변화시키는 조건으로 실험을 수행하였다. $PO_4-P$의 흡착량은 4~14 g/L 범위에서 3배 증가하였고, 제거율은 4~16 g/L 범위에서 28.6% 증가하였다. 최대 단분자층 흡착능($q_m$)과 결합세기(b)는 각각 0.10 mg/g, 0.06 L/mg으로 산출되었다. 또한 Langmuir 흡착등온식의 특징인 무차원상수($R_L$)는 0.37로 0과 1사이로 나타나 Langmuir 흡착등온식을 잘 표현하여 흡착에 용이함을 알 수 있었다. 따라서, 참나무를 원료로 제조한 바이오차는 농경지 유거수로부터 부영양화를 감소시키기 위한 $PO_4-P$ 흡착제로 용이하다고 판단된다.

• Environmental Engineering Research
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• 제21권3호
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• pp.304-310
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• 2016

Removal of arsenic (As) from soil aggregates with particle sizes of > 2.0, 2.0-0.25, 0.25-0.053, < 0.053 mm by soil washing of $KH_2PO_4$ and the kinetics of As releasing from soil aggregates were investigated. Effects of $KH_2PO_4$ concentration, ratio of liquid/soil and washing duration on the removal were fully explored. The results showed that the high As removal was obtained in > 2 mm aggregates (48.56%) and < 0.053 mm aggregates (42.88%) under the optimum condition ($KH_2PO_4$ concentration of 0.1 mol/L, and liquid/soil ratio (10 mL/g) for 360 min). 62.82% of As was extracted from aggregates with size less than 0.25 mm. Only 11.88% was contributed by the large aggregates (> 2.0mm). Using $KH_2PO_4$ washing, it was also found that extracted As is mainly in form of either specifically sorbed As or As associated with oxides of Fe and Al. Elovich model can describe the removal process of As more precisely than Two-constant kinetic models. The optimum washing conditions and removal process is also applied to bulk soil. This technique in this study is reliable, cost-effective and offers a great potential for practical application in soil remediation.

• Journal of Power Electronics
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• 제18권5호
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• pp.1585-1594
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• 2018

The estimation of $LiFePO_4$/graphite battery states suffers from the prominent hysteresis phenomenon between the respective open-circuit voltage curves towards charging and discharging. A lot of hysteresis models have been documented to investigate the hysteresis mechanism. This paper reviews and deeply interprets four non-electrochemical hysteresis models and some improvements. These models can be conveniently incorporated into commonly used equivalent circuit models to reproduce battery behaviors. Through simulation and experimental comparisons of voltage predictions and state-of-charge estimations, the pros and cons of these models are presented.

• Journal of the Korean Statistical Society
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• 제18권2호
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• pp.125-134
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• 1989

This paper presents optimum simple step-stress accelerated life test plans for the case where the test process is observed periodically at intervals of the same length. Two types of failure data, periodically observed complete data and periodically observed censored data, are considered. An exponential life distribution with a mean that is a log-linear function of stress, and a cumulative exposure model for the effect of changing stress are assumed. For each type of data, the optimum test plan which minimizes the asymptotic variance of the maximum likelihood estimator of the mean life at a design stress is obtained and its behaviors are studied.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.369-373
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• 2007

This paper presents an examination of theoretical scattering models for radar cross sections (RCS) of lossy dielectric cylinders, such as exact analytical solution, low frequency approximation (Rayleigh) and high frequency approximation (Physical Optics). The validity regions of the PO and Rayleigh models are closely examined with exact solution in terms of various wavelengths and dielectric constants of a circular cylinder. And also this paper examines the PO and Rayleigh models for back and forward scatter RCS of a cylinder at various incidence angles and polarizations. It was found that the PO and Rayleigh model have their validity regions for estimating the RCS of a circular cylinder.