• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.266-275
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• 2018

Herein, a novel operating life (OL) test method was evaluated with 200 mAh pouch-type lithium-ion batteries. By combining the calendar life (CL) test with intermediate pulse power cycling, more realistic life prediction was possible, which encompassed real operation of batteries accompanying with thermal acceleration. Larger capacity decrease and resistance increase of pouch cell were observed in the OL test, which was well explained using the SEI film growth model. After dissemble of pouch cell, capacity loss and resistance increase mostly occurred within anode, reflecting that SEI film growth on anode surface was highly attributable to cell degradation.

• Communications for Statistical Applications and Methods
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• 제28권2호
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• pp.99-118
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• 2021

In this paper, we introduce an extended form of the inverse power Lomax model via Marshall-Olkin approach. We call it the Marshall-Olkin inverse power Lomax (MOIPL) distribution. The four- parameter MOIPL distribution is very flexible which contains some former and new models. Vital properties of the MOIPL distribution are affirmed. Maximum likelihood estimators and approximate confidence intervals are considered under Type I censored samples. Maximum likelihood estimates are evaluated according to simulation study. Bayesian estimators as well as Bayesian credible intervals under symmetric loss function are obtained via Markov chain Monte Carlo (MCMC) approach. Finally, the flexibility of the new model is analyzed by means of two real data sets. It is found that the MOIPL model provides closer fits than some other models based on the selected criteria.

• 한국정밀공학회지
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• 제10권3호
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• pp.69-80
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• 1993

It is important to prevent roll failure in hot rolling process for reducing maintenance coat and production loss. Roll material and rolling conditions such as the roll force and torque have been intensively investigated to overcome the roll failures. In this study, a computer roll life prediction system under working condition is developed and evaluated on IBM-PC level. The system is composed and fatigue estimation models which are stress analysis, crack propagation, wear and fatigue estimation. Roll damage can be predicted by calculating the stress anplification, crack depth propagation and fatigue level in the roll using this computer model. The developed system is applied to a work roll in actual hot rolling process for reliability evaluation. Roll failures can be diagnosed and the propriety of current working condition can be determined through roll life prediction simulation.

• 한국재난정보학회 논문집
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• 제4권1호
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• pp.86-100
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• 2008

It is needed to classify the kinds of construction and demolition(c&d) debris to 6 catagories of waste concrete, waste asphalt concrete, waste wood, scraps, combustible waste and incombustible waste in order to properly do a separate discharge and to estimate unit generation rate in construction site. Also, in this case, the unit treating cost for mixed wastes should be applied with the unit treating cost for combustible waste. The construction standard materials estimation data is used for basic data for estimating unit generation rate. The mixed wastes in this data should be classified to waste wood, combustible waste and incombustible waste, and their ratio is obtained by using the unit generation rate of Asia Pacific Environment and Management Institute and Seoul Metropolitan Development Institute. The waste amounts generated from newly-built construction can be obtained from multiplying the loss rate by the amount of materials used from construction standard estimation data. Also, those from dismantling construction can be obtained by subtracting waste amount generated during newly-built construction from total input amount of materials in newly-built construction. Those in two cases can be used in construction site. It can be used for estimating the amount generated and establishing the treating plan in the case of setting up the policy of waste management and doing the environment impact assessment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권3호
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• pp.1040-1057
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• 2014

In this paper, a new bit rate estimation scheme is proposed to determine the bit rate for each subclass in an MPEG-2 TS to H.264/AVC transcoder after dividing an input MPEG-2 TS sequence into several subclasses. Video format transcoding in conventional IPTV and Smart TV services is a time-consuming process since the input sequence should be fully transcoded several times with different bit-rates to decide the bit-rate suitable for a service. The proposed scheme can automatically decide the bit-rate for the transcoded video sequence in those services which can be stored on a video streaming server as small as possible without losing any subject quality loss. In the proposed scheme, an input sequence to the transcoder is sub-classified by hierarchical clustering using a parameter value extracted from each frame. The candidate frames of each subclass are used to estimate the bit rate using a statistical analysis and a mathematical model. Experimental results show that the proposed scheme reduces the bit rate by, on an average approximately 52% in low-complexity video and 6% in high-complexity video with negligible degradation in subjective quality.

• 한국산업융합학회 논문집
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• 제23권5호
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• pp.853-863
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• 2020

As the battery ages, the internal resistance of the battery increases, so the loss due to the internal resistance increases at the same charging current, causing the battery temperature to rise, which further accelerates battery aging. Therefore, it is necessary to optimize the charging conditions according to the aging of the battery or the current charge amount, and to accurately estimate this, estimation of the parameters of the equivalent circuit is most important. This paper proposes a new measurement technique that can measure the internal resistance of a battery by analyzing a specific high frequency voltage and current applied to the battery. In addition, in order to test the validity of the proposed measurement technique, the current charging amount was estimated based on the measured internal resistance, and the terminal voltage of the constant current charging mode was automatically set and operated. As a result, good results were obtained regardless of the battery voltage. If this equipment is installed in the charging device, it is believed that it will be of great help in the stability management of the aging reusable battery.

• 한국유체기계학회 논문집
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• 제14권1호
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• pp.34-41
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• 2011

Fire characteristics can be analyzed more realistically by using more accurate properties related to the fire dynamics and one way to acquire these fire properties is to use one of the inverse property estimation techniques. In this study two optimization algorithms which are frequently applied for the inverse heat transfer problems are selected to demonstrate the procedure of obtaining pyrolysis properties of charring material with relatively simple thermal decomposition. Thermal decomposition is occurred at the surface of the charring material heated by receiving the radiative energy from external heat sources and in this process the heat transfer through the charring material is simplified by an unsteady 1-dimensional problem. The basic genetic algorithm(GA) and repulsive particle swarm optimization(RPSO) algorithm are used to find the eight properties of a charring material; thermal conductivity(virgin, char), specific heat(virgin, char), char density, heat of pyrolysis, pre-exponential factor and activation energy by using the surface temperature and mass loss rate history data which are obtained from the calculated experiments. Results show that the RPSO algorithm has better performance in estimating the eight pyrolysis properties than the basic GA for problems considered in this study.

• 한국전자파학회논문지
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• 제21권1호
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• pp.20-27
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• 2010

본 논문은 space-time signal processing(STAP)의 신호 모델과 불균일한 클러터 환경을 제시하고 이를 극복하고자 연구된 nonhomogeneity detector(NHD)의 사용 이후에도 일어나는 심각한 성능 저하를 극복하고자 중위수(median)를 이용한 간섭 공분산 행렬의 새로운 예측 방법을 제시하였다. 또한 대각 로드(diagonal loading)를 적용하여 고유값(eigen value) 특성을 개선시켰으며 signal to interference plus noise ratio(SINR) 손실을 계산하여 비교하였다. 마지막으로 modified sample matrix inversion(MSMI) 통계량으로 목표물 검출 능력을 비교한 결과 제시된 방법이 평균값(average)으로 정의된 기존의 방법보다 우수한 성능을 보임을 확인하였다.

• International Journal of Contents
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• 제11권1호
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• pp.7-14
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• 2015

In this paper, we derive the outage probability for M-ary phase shifting keying (MPSK) and M-ary quadrature amplitude modulation (MQAM) burst transmission (BT) of adaptive decode-and-forward (ADF) cooperative relay systems over quasi-static Rayleigh fading channels. Within a burst, there are pilot symbols and data symbols. Pilot symbols are used for channel estimation schemes and each relay node's transmission mode selection schemes. At first, we focus on ADF relay systems in which the probability density function (PDF) is derived on the basis of error events at relay nodes corresponding to channel estimation errors. Next, the average outage probability is derived as an approximate expression for an arbitrary link signal-to-noise ratio (SNR) for different modulation orders. Its accuracy is demonstrated by comparison with simulation results. Further, it is confirmed that BT-ADF relay systems with pilot symbol based channel estimation schemes enables to select correctly decoded relay nodes without additional signaling between relay nodes and the destination node, and it is verified that the ideal performance is achieved with small SNR loss.

• 한국통신학회논문지
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• 제29권7C호
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• pp.946-953
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• 2004

고속 탐색 및 기존의 이진 연산 움직임 추정 알고리즘은 연산량 및 처리시간을 대폭 줄일 수 있지만 전역 탐색 움직임 추정 알고리즘에 비하여 성능이 떨어지는 단점이 있다. 따라서 본 논문에서는 하드웨어 구현이 용이하고 움직임 추정을 고속으로 수행 할 수 있는 새로운 BC-ABBM 알고리즘을 제안하였다. BC-ABBM 알고리즘은 움직임 추정시 필요한 연산을 이진 연산으로만 수행하면서 전역 탐색에 근접한 성능을 나타낸다. BC-ABBM 알고리즘의 움직임 추정 성능은 QCIF와 CIF 포맷의 100프레임 영상을 이용하여 분석하였다. BC-ABBM 알고리즘의 PSNR 성능은 전역 탐색 알고리즘보다 약 0.04dB 정도 떨어지지만, 고속 탐색 알고리즘 및 기존의 이진 연산 알고리즘보다는 약 0.6∼l.4dB 정도 우수함을 모의실험을 통해 확인하였다.