• 한국가구학회지
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• 제10권2호
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• pp.73-78
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• 1999

This paper describes the relationship between the bending strength properties of sloped finger-jointed woods and the acoustic emissions(AEs) generated during the test. Rhus verniciflua pieces were cut in sloped-finger types and glued with three kinds of adhesives(polyvinyl acetate, polyvinyl-acryl acetate and oilic urethane resin). The slope ratios of finger joints were 0, 1.0, 1.5, and 2.0. The AE cumulative event count and cumulative count were measured during the bending test. The results were as follows: The lower the bending strength(load) was, the generation time of AE event count got and the higher the increasing rate of AE event count became in the sloped finger-jointed specimens bonded with polyvinyl acetate, polyvinyl-acryl acetate oilic urethane resin adhesives. Therefore, the slope from load-AE cumulative event count was very steep. The patterns of AE event count and count were very similar. The relationship between the MOR and the AE parameter from load and AE cumulatve event count in the early stage of the sloped finger-jointed specimens bonded with polyvinyl acetate, polyvinyl-acryl and oilic urethane resin adhesives was much greater than that between the MOE and the MOR. Therefore, the AE signals obtained during bending test are useful for estimating the strength of sloped finger-jointed Rhus verniciflua specimens.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.30-36
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• 1999

소나무를 재료로 경사핑거접합법으로 레소시놀계수지, 유용성 우레탄수지, 초산비닐수지, 초산비닐과 아크릴을 혼합한 수지접착제롤 사용하여 제작한 시험재의 휨강도 성능과 휨 시험시 발생하는 AE 특성에 대한 연구결과는 다음과 같다. 초산 비닐, 유용성 우레탄 수지접착제를 사용한 소나무경사 핑거접합재의 하중과 AE 사상총수는 휨 강도가 낮을수록 빠른 시기부터 AE가 발생하고 AE의 증가속도가 빨라 하중-AE 사상총수의 관계곡선의 기울기가 급격하게 나타났다. 레소시놀 수지 접착제로 제작한 시편은 아주 낮은 하중에서부터 하중이 증가함에 따라 연속적으로 AE가 발생하였고 발생수도 많았다. 경사 핑거접착제의 휨 하중과 AE 특성간에는 서로 잘 대응되어 휨강도 측정이나 보정은 휨 탄성계수로서는 예측이 어렵지만 하중과 AE, 사상총수의 초기 치로부터 얻어지는 AE지표 치로서 휨 강도의 예측이나 보증이 가능 할 것으로 판단된다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.721-725
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• 2004

Multiple-count problem is occurred when rectangle objects span across several buckets. The Cumulative Density (CD) histogram is a technique which solves multiple-count problem by keeping four sub-histograms corresponding to the four points of rectangle. Although it provides exact results with constant response time, there is still a considerable issue. Since it is based on a query window which aligns with a given grid, a number of errors may be occurred when it is applied to real applications. In this paper, we proposed selectivity estimation techniques using the generalized cumulative density histogram based on two probabilistic models: (1) probabilistic model which considers the query window area ratio, (2) probabilistic model which considers intersection area between a given grid and objects. In order to evaluate the proposed methods, we experimented with real dataset and experimental results showed that the proposed technique was superior to the existing selectivity estimation techniques. The proposed techniques can be used to accurately quantify the selectivity of the spatial range query on rectangle objects.

• Communications for Statistical Applications and Methods
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• 제25권1호
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• pp.29-42
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• 2018

We combine the integer-valued GARCH(1, 1) model with a generalized regime-switching model to propose a dynamic count time series model. Our model adopts Markov-chains with time-varying dependent transition probabilities to model dynamic count time series called the generalized regime-switching integer-valued GARCH(1, 1) (GRS-INGARCH(1, 1)) models. We derive a recursive formula of the conditional probability of the regime in the Markov-chain given the past information, in terms of transition probabilities of the Markov-chain and the Poisson parameters of the INGARCH(1, 1) process. In addition, we also study the forecasting of the Poisson parameter as well as the cumulative impulse response function of the model, which is a measure for the persistence of volatility. A Monte-Carlo simulation is conducted to see the performances of volatility forecasting and behaviors of cumulative impulse response coefficients as well as conditional maximum likelihood estimation; consequently, a real data application is given.

• 한국정밀공학회지
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• 제12권9호
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• pp.74-85
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• 1995

The purpose of this paper is to evaluate the grade of WA vitrified and resinoid bond grinding wheels by the sue of AE measuring system. When the manufactured 48 kinds of specimens were scratched by the method of OKOSHI'S grade test, the relationship between the amount of bit scratch depth of grinding wheel specimens and the character- istics of AE signals, and the relationship of AE counts and grade were considered as fololws; (1) The higher the grades are AE cumlulative event counts N and AE event count rate n, the smaller the values tend to be. But A $E_{rms}$is in reverse. (2) In the case of same grade, the smaller the grain size is, the higher the value of AE cumulative event counts N and A $E_{rms}$is results of comparison and observation. The grinding wheel with lower elasticity and with higher percentage of pore detected higher value of AE cumula- tive event counts N than with higher elasticity and lower percentage of pore. But A $E_{rms}$ is in reverse. (3) AE cumulative event counts N and bit scratch depth h have normally one to one correspondence. (4) It can be expected that quantitative evaluations of grade by using AE have been carried out by the wave observation of AE signal in line with the relationship between load speed of bit and AE cumulative event counts N & AE event count rate n.' AE event count rate n.ate n.

• Industrial Engineering and Management Systems
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• 제4권1호
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• pp.75-81
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• 2005

Borror et al. discussed the EWMA(Exponentially Weighted Moving Average) chart to monitor the count of defects which follows the Poisson distribution, referred to the $EWMA_c$ chart, as an alternative Shewhart c chart. In the $EWMA_c$ chart, the Markov chain approach is used to calculate the ARL (Average Run Length). On the other hand, in order to monitor the process fraction defectives P in high-yield processes, Xie et al. presented the CCC(Cumulative Count of Conforming)-r chart of which quality characteristic is the cumulative count of conforming item inspected until observing $r({\geq}2)$ nonconforming items. Furthermore, Ohta and Kusukawa presented the $CS(Confirmation Sample)_{CCC-r}$ chart as an alternative of the CCC-r chart. As a more superior chart in high-yield processes, in this paper we present an $EWMA_{CCC-r}$ chart to detect more sensitively small or moderate shifts in P than the $CS_{CCC-r}$ chart. The proposed $EWMA_{CCC-r}$ chart can be constructed by applying the designing method of the $EWMA_C$ chart to the CCC-r chart. ANOS(Average Number of Observations to Signal) of the proposed chart is compared with that of the $CS_{CCC-r}$ chart through computer simulation. It is demonstrated from numerical examples that the performance of proposed chart is more superior to the $CS_{CCC-r}$ chart.

• Journal of the Korean Wood Science and Technology
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• 제31권2호
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• pp.84-91
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• 2003

본 연구에서는 3 수종(이태리 포플러, 소나무, 굴참나무재)을 공차별(0, 0.15, 0.3, 0.45 mm)로 초산비닐 수지와 레소시놀-페놀 공축합 수지를 이용하여 접합 제작하였다. 휨시험에서 핑거공차에 따라서 검출되는 AE와 휨강도성능 특성을 살펴본 결과는 다음과 같았다. 레소시놀재의 AE파 발생시기가 초산재보다 빨랐으며, 레소시놀재의 AE파 사상총수는 하중의 증가와 함께 계속적으로 증가하였으며 총발생 사상총수도 초산재보다 휠씬 많이 나타났다. 또한, 레소시놀재의 AE파 사상총수는 낮은 하중에서도 많은 개수가 발생하였다. 비례한도 내에서도 레소시놀 접착제를 사용한 경우에는 많은 AE파가 검출되었다. 따라서 레소시놀 접착제로 접착한 핑거 접합재의 휨시험으로부터 얻은 AE 신호는 핑거공차에 따른 접합재의 강도 예측이나 보증에 이용 가능할 것으로 판단되었다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권2호
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• pp.129-140
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• 2013

As a fundamental experimental study for reliability improvement of lithium ion secondary battery, degradation mechanism was investigated by microscopic observation and acoustic emission monitoring. Microstructural observation of the decomposed battery after cycle test revealed mechanical and chemical damages such as interface delamination, microcrack of the electrodes, and solid electrolyte interphase (SEI). Acoustic emission (AE) signal was detected during charge and discharge of lithium ion battery to investigate relationships among cumulative count, discharge capacity, and microdamages. With increasing number of cycle, discharge capacity was decreased and AE cumulative count was observed to increase. Observed damages were attributed to sources of the detected AE signals.

• 비파괴검사학회지
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• 제33권2호
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• pp.198-204
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• 2013

리튬이온전지의 충/방전 열화 과정에서 발생하는 음향방출 신호를 검출하여 누적카운트, 방전용량, 미세손상 사이의 상관관계를 확인하였다. 상용 리튬이온전지를 사용하여 가속 충/방전 싸이클 실험을 하면서 음향방출 신호를 수집하였다. 다수의 음향방출 신호가 전지의 충전 및 방전 과정에서 각각 검출되었다. 충/방전 열화 싸이클이 증가함에 따라 전지 용량은 감소하였고 음향방출 신호의 누적카운트는 증가하는 경향을 보였다. 충/방전 후 전지를 분해하여 내부 전극 손상을 관찰한 결과 전극 계면 박리 및 미소균열이 다수 확인되었으며, 이러한 기계적 손상이 음향방출원인 것으로 판단된다. 전지 방전용량과 음향방출 누적카운트 사이에는 선형의 상관관계가 있었으며, 이로부터 음향방출법을 이용한 리튬이온전지 열화 평가 가능성을 제안하였다.

• 한국해양공학회지
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• 제26권5호
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• pp.5-10
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• 2012

In this study, carbon steel (A53) is used as the material for the pipes in a marine plant and ship industry. Welds are necessary to join the carbon steel, and the effect of this welding on the properties of the carbon steel has been studied by many researchers. In this study, the dynamic behavior of welded carbon steel was studied using an acoustic emission (AE) technique, which is a nondestructive test. There are numerous AE parameters that can be used to analyze the damage behavior of carbon steel by external loading. The AE parameters of energy, cumulative count, amplitude, and AE event were used, and each parameter was differentiated according to the degree of damage to the carbon steel. The energy showed a high level at the elastic range of the load curve, while the amplitude had the highest value at the hardening region. The cumulative count showed a growth tendency similar to the loading curve. In addition, an ultrasonic technique and hardness test were applied to evaluate the mechanical properties according to the base zone, HAZ region, and weld zone of the weld specimen. The velocity and attenuation ratio showed little change between zones, and an evaluation of the ultrasonic waves on each zone of the specimen was found to be a useful method to clarify the mechanical properties of the carbon steel.