• Journal of Power Electronics
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• 제15권2호
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• pp.346-355
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• 2015

On the basis of the conventional PID control algorithm, a modified adaptive PID (MA-PID) control algorithm is presented to improve the steady-state and dynamic performance of closed-loop systems. The proposed method has a straightforward structure without excessively increasing the complexity and cost. It can adaptively adjust the values of the control parameters ($K_p$, $K_i$ and $K_d$) by following a new control law. Simulation results show that the line transient response of the MA-PID is better than that of the adaptive digital PID because the differential coefficient $K_d$ is introduced to changes. In addition, experimental results based on a FPGA indicate that the MA-PID control algorithm reduces the recovery time by 62.5% in response to a 1V line transient, 50% in response to a 500mA load transient, and 23.6% in response to a steady-state deviation, when compared with the conventional PID control algorithm.

• 한국전산구조공학회논문집
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• 제13권4호
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• pp.405-415
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• 2000

한 구조물에 작용하는 풍압력 시계열이 자기회귀 이동평균(ARMA) 모델을 사용하여 모델화 된다. AR 과정에서 시계열의 현재 값은 유한한 수의 이전 값들의 선형적 결합과 한 백색잡음에 의해 나타난다. MA 과정에서 시계열의 현재값은 유한한 수의 이전 백색잡음들에 선형적이다. ARMA 과정은 AR과 MA 과정의 결합이다. 본 논문에서, AR, MA와 ARMA 모델이 풍압력 시계열에 적용되고, 데이터를 나타내기에 가장 적합한 ARMA 모델을 선정하는 과정이 소개된다. 모델의 변수들은 최대 가능도법을 사용하여 산정되고, 압력 시계열의 시간적 복잡성의 척도인 모델 차수를 최적화하기 위해 AICC 모델 선정 기준이 사용된다. 또한, 모델의 유효성을 조사하기 위해 LBP 검사가 사용된다. 본 연구로부터, AR 과정이 풍압력 시계열을 나타내기에 가장 적합하다는 결론이 얻어진다.

• 한국제4기학회지
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• 제15권1호
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• pp.37-45
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• 2001

제주도에 분포하는 스코리아콘의 사면발달을 밝히기 위하여 49개 스코리아콘을 대상으로 화산체의 비고, 저경에 대한 비고의 비율($H_{co}$/$W_{co}$), 저경과 화구경의 차에 대한 비고의 비율($H_{co}$/$W_{co-cr}$), 및 사면각등의 지형특성치를 계측하였다. 스코리아콘의 형성시기가 오래될수록 지형특성치는 일정한 비율로 감소하므로 화산체의 형태비교학적 방법에 의해 스코리아콘의 형성시기를 추정할 수 있다. 스코리아콘의 화구는 침식작용으로 메워지며 결국에는 사라지게 되므로 화산체의 형성시기와 가장 높은 상관관계를 보이는 지형특성치는 저경과 화구경의 차에 대한 비고의 비율이나 평균사면각($\theta_{ave}$) 이다. 스코리아콘의 평균사면각은 $\theta$$_{ave}$ : $tan^{-1}$〔2.$H_{co}$/$W_{co-cr}$〕로서 구할 수 있다. 제주도는 플라이스토세에 네 번에 걸친 분화활동기를 통하여 형성되었다. 제4분출기(0.1~0.025Ma)에 형성된 최신의 스코리아콘은 평균사면각의 평균치가 23.6$\pm$1.7$^{\circ}$인데 비하여, 제3분출기(0.3~0.1Ma)와 제2출기(0.6~0.3Ma)의 스코리아콘은 각각 18.9$\pm$$1.7^{\circ}C$및 12.6$\pm$$1.9^{\circ}C$이다.다.

• 대한전기학회논문지
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• 제35권10호
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• pp.438-444
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• 1986

The signal can be modeled as a linear combination of its past values and present and past values of a hypothetical input to system whose output is given signal. Using this model spectral estimation problem can be reduced to estimate the ARMA parameters. This paper presents recursive modified instrumental variable algorithm which can estimate AR and MA parameters. For more accurate estimation, overdetermined modified IV algorithm is also derived. Computer simulations are presented to illustrate the above methods.

• Journal of Oral Medicine and Pain
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• 제25권4호
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• pp.345-353
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• 2000

This study was to investigate normal salivary flow rates and normal indices of Quantitative analysis of salivary scintigraphy. 96 adult volunteers were studied by Questionnaire evaluating salivary conditions and clinical examinations. 35(male 23, female 12, age range 23-31years) that absented subjective and objective symptoms related saliva were classified as normal group. The normal group underwent measurement unstimulated and stimulated salivary flow rates and salivary scintigraphy. The obtained results were as follows: 1. There were not significant in sex differences of unstimulated and stimulated salivary flow rates. The unstimulated salivary flow rate was $0.66{\pm}0.41g/min$, stimulated salivary flow rates was $1.61{\pm}0.69g/min$. 2. As comparing of parameters of salivary scintigraphy, the Uptake ratio(UR), $T_{max}$, $T_{min}$, Maximum accumulation (MA), Maximum secretion(MS) of parotid and submandibular glands were not significant in sex and side-ralated differences. 3. The UR, $T_{max}$, MA, MS of parotid gland were significantly higher than those of submandibular gland; in the parotid gland, UR, $3.67{\pm}0.88$, $T_{max}$, $18.77{\pm}0.43min$, MA, $41.35{\pm}9.22%$, MS, $43.13{\pm}9.13%$; in the submandibular gland, UR, $3.04{\pm}0.10$, $T_{max}$, $18.48{\pm}0.52min$, MA, $36.47{\pm}14.18%$, MS, $36.88{\pm}12.20%$. 4. As classifying of time-activity curve, the most of parotid gland was N-type(97.1%), submandibular gland was observed in order of M-type(67.1%), N-type(21.4%), F-type(11.4%), however, was not observed S-type. 5. As the type of time-activity curve of submandibular gland was more flattened, the UR, $T_{max}$, MA, MS were significantly decresed.

• 폴리머
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• 제36권4호
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• pp.507-512
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• 2012

순수 PMMA와 methacryl-polyhedral oligomeric silsesquioxane(Ma-POSS)를 5 wt% 첨가한 PMMA를 박막(~650 nm)과 초박막(~50 nm)으로 제조하였으며, 유리전이온도($T_g$)와 등온 물리적 시효에 미치는 박막의 두께에 미치는 POSS의 첨가 효과를 시차주사열량계(DSC)를 이용하여 조사하였다. 초박막화와 Ma-POSS의 첨가로 인해 $T_g$ 감소가 관찰되었다. 또한 등온 물리적 시효에 의한 엔탈피 완화값(${\Delta}H_{Relax}$)도 초박막화 Ma-POSS를 첨가하였을 때 감소하였다. 시효시간에 따른 ${\Delta}H_{Relax}$ 데이터에 KWW(Kohlrausch-Williams-Watts)식을 적용하여 최대 엔탈피(${\Delta}H_{\infty}$), 이완시간(${\tau}$) 그리고 이완시간의 분포상수(${\beta}$)를 결정하였으며 이를 비교 분석하였다.

• Geomechanics and Engineering
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• 제11권4호
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• pp.571-585
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• 2016

The crest of the Pubugou central core rockfill dam (CCRD) cracked in the first and second impounding periods. To evaluate the safety of the Pubugou CCRD, an inversion analysis of the constitutive model parameters for rockfill materials is performed based on the in situ deformation monitoring data. The aim of this work is to truly reflect the deformation state of the Pubugou CCRD and determine the causes of the dam crest cracks. A novel real-coded genetic algorithm based upon the differences in gene fragments (DGFX) is proposed. It is used in combination with the radial based function neural network (RBFNN) to perform the parameters back analysis. The simulated settlements show good agreements with the monitoring data, illustrating that the back analysis is reasonable and accurate. Furthermore, the deformation gradient of the dam crest has been analysed. The dam crest has a great possibility of cracking due to the uncoordinated deformation, which agrees well with the field investigation. The deformation gradient decreases to the value lower than the critical one and reaches a stable state after the second full reservoir.

• Asian-Australasian Journal of Animal Sciences
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• 제15권3호
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• pp.315-320
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• 2002

Test-day records (n=13677) sampled from 896 ewes in 5-9 (${\mu}$=7.5) monthly test-days were used to estimate genetic and phenotypic parameters of test-day yields, lactation milk yield (TMY), length of the milking period (DAYS) and three measures of persistency of milk yield in Boutsico dairy sheep. Τhe measures of persistency were the slope of the regression line (${\beta}$), the coefficient of variation (CV) of the test-day milk yields and the maximum to average daily milk yield ratio (MA). The estimates of variance components were obtained under a linear mixed model by restricted maximum likelihood. The heritability of test-day yields ranged from 0.15 to 0.24. DAYS were found to be heritable ($h^2$=0.11). Heritability estimates of ${\beta}$, CV and MA were 0.15, 0.13, 0.10, respectively. Selection for maximum lactation yields is expected to result in prolonged milking periods, high rates of decline of yields after peak production, variable test-day yields and higher litter sizes. Selection for flatter lactation curves would reduce lactation yields, increase slightly the length of the milking period and decrease yield variation as well as litter size. The most accurate prediction of TMY was obtained with a linear regression model with the first five test-day records.

• Ocean and Polar Research
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• 제24권3호
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• pp.197-205
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• 2002

Total magnetic field and high-resolution bathymetric data were collected over nine seamounts to the northwest of the Marshall Islands in the western Pacific. Magnetic parameters including inclination and declination were calculated from the magnetic anomalies using inversion algorithm of Plouff (1976), and a corresponding paleomagnetic pole was determined with the magnetic parameters. The paleomagnetic poles determined in this study were compared with the previous apparent polar wander path (APWP) of Pacific plate. Most seamounts of the study area have normal polarity. The study reveals that all nine seamounts in the study area formed in the southern hemisphere during the Cretaceous based on their comparison with the APWP of Pacific plate. The ages estimated from paleomagnetic poles can be divided by age into three groups: the oldest (OSM1 and OSM3), middle age (OSM2, OSM4, and 6-2), and the youngest (OSM5-1, 5-2, 5-3, and 6-1). The fermer two groups and the latter seem to be coincident with two distinct pulses of Cretaceous volcanic activity (115-90 Ma and 83-65 Ma). As a whole the seamounts at southwest of the study area are older than at those northeast.

• Advances in environmental research
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• 제12권1호
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• pp.17-40
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• 2023

This article presents studies of the adsorption process in a continuous system of fluoride solutions at a concentration of 30 mg/L using a bone char packed in fixed-bed columns, as well as regeneration studies in the same system using HNO₃, HCl and NaOH at 0.01, 0.1 and 1 M. The Thomas Model, Artificial Neural Networks (ANNs), Numerical Integration and Mass Transfer Zone were used for the modeling of asyemmetrical breakthrough curves obtained from the fluoride adsorption on bone char. The maximum adsorption capacity of the breakthrough curves was estimated, and various design parameters of the columns were obtained for the different operating conditions. Results showed that an improvement in the modeling capabilities of the Thomas model can be obtained using ANNs. Moreover, ANNs are useful for determining reasonable and accurate design parameters of packed-bed adsorption columns. This modeling approach can be useful for the process system engineering of dynamic adsorption systems involved in the field of water treatment and purification. It is important to highlight that the obtained results indicate that, when using HCl or HNO₃ at a concentration of 0.1 M, a large number of adsorption-desorption cycles are obtained and, therefore, the highest values of adsorption capacity, which leads to a reduction in operation costs.