• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.156-167
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• 2007

In this paper, we develop the model based prediction algorithm for Variable-Bit-Rate(VBR) video traffic with regular Group of Picture(GOP) pattern. We use multiplicative ARIMA process called GOP ARIMA (ARIMA for Group Of Pictures) as a base stochastic model. Kalman Filter based prediction algorithm consists of two process: GOP ARIMA modeling and prediction. In performance study, we produce three video traces (news, drama, sports) and we compare the accuracy of three different prediction schemes: Kalman Filter based prediction, linear prediction, and double exponential smoothing. The proposed prediction algorithm yields superior prediction accuracy than the other two. We also show that confidence interval analysis can effectively detect scene changes of the sample video sequence. The Kalman filter based prediction algorithm proposed in this work makes significant contributions to various aspects of network traffic engineering and resource allocation.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.1
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• pp.136-142
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• 2007

This paper proposes a new approach on nonlinear maneuvering target tracking. In this paper, proposed algorithm is the Kalman filter based on the adaptive interactive multiple model using the concept of predicted impact point and utilize modified Kalman filter regarding the error between measurement position and predicted impact point. The unknown target acceleration is regarded as an additional process noise to the target model, and each sub-model is characterized in accordance with the valiance of the overall process noise which is obtained on the basis of each acceleration interval. To compensate the decreasing performance of Kalman filter in nonlinear maneuver, we construct optional algorithm to utilize proposed method or Kalman filter selectively. To effectively estimate the acceleration during the target maneuvering, the rapid increase of the noise scale is recognized as the acceleration to be used in maneuvering target's movement equation. And a few examples are presented to show suggested algorithm's executional potential.

• Vascular Specialist International
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• v.34 no.4
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• pp.103-108
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• 2018

Purpose: Surgery is the most common risk factor for pulmonary embolism (PE) in patients with a recent venous thromboembolism (VTE). This study reviewed clinical outcomes of preoperative inferior vena cava filter (IVCF) use in patients with acute VTE during abdominal-pelvic cancer or lower extremity orthopedic surgeries. Materials and Methods: We retrospectively analyzed 122 patients with a recent VTE who underwent IVCF replacement prior to abdominal-pelvic cancer or lower extremity orthopedic surgery conducted between January 2010 and December 2016. Demographics, clinical characteristics, postoperative IVCF status, risk factors for a captured thrombus, and clinical outcomes were collected for these subjects. Results: Among the 122 study patients who were diagnosed with acute VTE in the prior 3 months and underwent preoperative IVCF replacement, 70 patients (57.4%) received abdominal-pelvic cancer surgery and 52 (42.6%) underwent lower extremity orthopedic surgery. There were no perioperative complications associated with IVCF in the study population and no cases of symptomatic PE postoperatively. A captured thrombus in the filter was identified postoperatively in 16 patients (13.1%). Logistic regression analysis indicated that postoperative anticoagulation within 48 hours significantly reduced the risk of a captured thrombus (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.08-0.94; P=0.032). Conclusion: A captured thrombus in preoperative IVCF was identified postoperatively in 16 patients (13.1%). Postoperative anticoagulation within 48 hours reduces the risk of captured thrombus in these cases.

• Journal of Environmental Science International
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• v.21 no.5
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• pp.613-622
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• 2012

A pilot-scale pulse-jet bagfilter was designed, built and tested for the effects of four operating conditions (filtration velocity, inlet dust concentration, pulse pressure, and pulse interval time) on the total system pressure drop, using coke dust from a steel mill factory. Two models were used to predict the total pressure drop according to the operating conditions. These model parameters were estimated from the 180 experimental data points. The empirical model (EM) with filtration velocity, areal density, inlet dust concentration, pulse interval time and pulse pressure shows the best correlation coefficient (R=0.971) between experimental data and model predictions. The empirical model was used as it showed higher correlation coefficient (R=0.971) compared to that of the Multivariate linear regression(MLR) (R=0.961). The minimum pulse pressure predicted by empirical model (EM) was 5kg/$cm^2$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1854-1862
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• 2000

Input shaping method is to convolute input shaper, which is sequence of impulses, with reference input command not to excite the natural frequency of system. To reduce residual vibration for the ch ange of frequency, the number of impulses should be increased. Until now, amplitudes and time interval of those has been searched from the derivative of residual vibration. However, if time interval of impulses is fixed as the half of vibration period of system, input shaper H(z) in z-domain becomes (I-pz-1)n/K in which increasing n is the mean that robustness for change of parameter is improved. Also, design of many types of input shapers in z-domain is very easy because sensitivity curve is displayed with $\mid$H(z)zn$\mid$$\times$100. In the z-domain, EI(Extra-Insensitive) input shaper could be designed without solving nonlinear simultaneous equations as design in continuous time domain. In addition to, the design possibility of input shaper for a damped system was shown.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.377-381
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• 2006

A seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. General indicator of gas hydrate in seismic data is commonly inferred from the BSR(Bottom Simulating Reflector) that occurred parallel to the sea floor, amplitude decrease at the top of the BSR, amplitude blanking at the bottom of the BSR, decrease of the interval velocity and the reflection phase reversal at the BSR. In this paper we had analyzed optimum parameters of the field data to detect the 9as hydrate. Shot delay correction is applied 95ms, spherical divergence correction is applied velocity library 3, bandpass filter is applied 25-30-115-120Hz deconvolution operator length is applied 60ms, lag is 6ms and accurate velocity analysis NMO correction, stack is performed. Geobit 2.11.0 developed by the KIGAM was used for all data processing. Processing results say that the BSR occurred parallel to the sea floor were shown at 3,150m/s of two way travel time from the sea floor through shot point 5,000-5,610, and identified the interval velocity decrease around BSR and the reflection phase reversal corresponding to the reflection at the sea floor.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.335-335
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• 2020

기저유출 분리 기법은 하천에서 관찰되는 총 유출을 직접유출과 기저유출로 분리하는 기술이다. 기저유출 분리 기법은 도식적(graphical) 방법, 디지털 필터(digital filter) 방법, 통계학적 방법, 해석적 방법 등 다양하다(Valent와 Bulík, 2016). 금회 연구에서는 이 가운데 도식적 방법을 이용한 기저유출 분리 방법에 대한 적용성을 평가하였다. 금회 연구에서 수행된 도식적 기저유출 분리 방법은 HYSEP 프로그램에 포함되어 있는 local minimum method(LMM), fixed interval method(FIM), sliding interval method(SIM)이고(Sloto and Crouse, 1996), 각각의 방법은 대리 수위관측소의 관측 일 유량(2013년~2017년)에 적용되었다. 분석에 사용된 세 가지 방법은 동일하게 유역면적의 함수인 기저유출 분리에 사용되는 간격(2N∗)만으로 기저유출을 분리하므로 객관적인 적용이 가능하다. 각각의 분석 방법에 의한 기저유출 분리의 적절성 평가를 위해 2017년의 유황곡선을 이용하여 검토하였다. 구체적으로 유황 곡선의 지표 유량인 풍수량, 평수량, 저수량을 기준으로 각각의 지표 유량 이하에 대한 관측 유량과 추정된 기저유량의 결정계수를 산정하였다(Table 1). 이는 유량의 규모가 작을수록 지표유출 보다는 기저유출의 영향이 커짐을 고려한 것이다. 분석 결과, SIM이 모든 지표 유량 기준에서 가장 좋은 결과를 보였다. 또한, 기저유출 지표(base flow index; BFI)에서도 SIM과 FIM은 약 0.46으로 유사한 반면, LMM은 0.23으로 분석되어 두 방법과 큰 차이를 보였다.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.80-85
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• 2008

Catalytic filter is capable of performing shallow bed dust filtration plus a catalytic reaction, promoted by a catalyst deposited in its inner structure. Such a feature may allow potential cost and space reduction in several environmental applications. Dust filtration and halogenated volatile organic compound (1,2-dichlorobenzene) destruction were carried out in a lab-scale reactor. $WO_3-V_2O_5/TiO_2$ supplied by MaGreen, which showed high catalytic acitivity at low temperature, was used as a catalyst. P-84 that can be operated under $250^{\circ}C$ was used as a felt. The catalytic activity and filtration efficiency of catalytic filters were investigated under the operating conditions, including temperature, face velocity, and dust concentration. The catalytic activity of catalytic filter increased with increasing temperature and the amount of catalyst loaded. The test results showed that the filtration efficiency was primarily affected by the face velocity. Pressure drop variations as a function of time were investigated for a variety of conditions. In case of virgin filter, a dramatic decrease in the pulse interval and a slightly increase in the base line pressure drop were observed. A relatively slow pressure drop build-up was recorded for the catalytic filter due to smooth and slippery surface characteristics of nanofiber. The catalytic filter indicated that high filtration efficiency over 99.98% and high catalytic activity over 90% at 1 m/min and $210^{\circ}C$.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.130-133
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• 2005

This paper presents the efficient method to detect the defective detectors of the SWIR band of SPOT 4. The key of this method are to flatten the baseline of the data using high pass band filter instead of differentiation. This method is made up six steps. First step is to apply image enhancement techniques to enhance the lines imaged by defective detector and improve the quality of an image. Second step is processed by summing the enhanced image in line direction. These summed data have the peaks that represent the defective detectors and the curved baseline characterized by the reflectivity of Earth surface. In order to exactly detect these peaks, third step is to flatten the curved baseline using high pass filtering in the frequency domain. In fourth step, the data with flat baseline is normalized to have zero mean and unity standard deviation. In fifth step, the defective detectors are detected using $99.9\%$ confidence interval. Finally, after removing the detected ones in summed data, the steps from third to five are iterated. Three SPOT 4 images, which have different reflectivity of Earth surface and different sensor, were used to validate this method. The overall accuracy of detection for three images was $97.9\%$. This result shows that this method can detect efficiently the lines made by defective detectors.

• Journal of the Korean Chemical Society
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• v.3 no.1
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• pp.23-27
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• 1954

The relation between the height of ascending solvents and its velocity were studied with strips of Toyo No. 50 filter paper. The filter paper strip of 3cm width and cat 30 cm length is hooked down or fixed between two sheets of glass plates inside a cylinder containing the solvent, in which the lower end of the strip is dipped. As the solvents, acetone, hydrochloric acid, water or mixtures of these are used. For short time intervals, Ostwald's folmula $h = Kt^n$ was found to be most suitable to express the relation between the height of the solvent front, h, and time, t. For longer time intervals, results will be discussed in the next paper. The mean values of the constant m in the above formula for pure acetone and pure water were 0.44 and 0.485, respectively, and that of K were 0.05 and 2.4, respectively. The time interval whose the above formula applies, for each solvent was 2 hours for the former, and a half hour for the later, respectively. The movement of solutes, such as $Cu^{++}$ and $Fe^{++}$ showed that the Rf values of solutes become constant values after a long periods; e.g., ca. 6 hours with 10N-HCl-Acetone (1 : 9) solvent.