• Journal of Computational Design and Engineering
• /
• v.2 no.2
• /
• pp.113-118
• /
• 2015

An important problem in low-dose CT is the image quality degradation caused by photon starvation. There are a lot of algorithms in sinogram domain or image domain to solve this problem. In view of strong self-similarity contained in the special sinusoid-like strip data in the sinogram space, we propose a novel non-local filtering, whose average weights are related to both the image FBP (filtered backprojection) reconstructed from restored sinogram data and the image directly FBP reconstructed from noisy sinogram data. In the process of sinogram restoration, we apply a non-local method with smoothness parameters adjusted adaptively to the variance of noisy sinogram data, which makes the method much effective for noise reduction in sinogram domain. Simulation experiments show that our proposed method by filtering in both image and projection domains has a better performance in noise reduction and details preservation in reconstructed images.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.1
• /
• pp.64-88
• /
• 2024

Security and reliability are the utmost importance facts in intelligent networked vehicles. Stochastic Petri Net and Z (SPZN) as an excellent formal verification tool for modeling concurrent systems, can effectively handles concurrent operations within a system, establishes relationships among components, and conducts verification and reasoning to ensure the system's safety and reliability in practical applications. However, the application of a system with numerous nodes to Petri Net often leads to the issue of state explosion. To tackle these challenges, a refinement and abstraction method based on SPZN is proposed in this paper. This approach can not only refine and abstract the Stochastic Petri Net but also establish a corresponding relationship with the Z language. In determining the implementation rate of transitions in Stochastic Petri Net, we employ the interval average and weighted average method, which significantly reduces the time and space complexity compared to alternative techniques and is suitable for expert systems at various levels. This reduction facilitates subsequent comprehensive system analysis and module analysis. Furthermore, by analyzing the properties of Markov Chain isomorphism in the case study, recommendations for minimizing system risks in the application of intelligent parking within the intelligent networked vehicle system can be put forward.

• Atmosphere
• /
• v.21 no.4
• /
• pp.337-347
• /
• 2011

In this paper, we developed a detection and correction method of noisy pixels embedded in the time series of normalized difference vegetation index (NDVI) data based on the spatio-temporal continuity of vegetation conditions. For the application of the method, 25-year (1982-2006) GIMMS (Global Inventory Modeling and Mapping Study) NDVI dataset over the Korean peninsula were used. The spatial resolution and temporal frequency of this dataset are $8{\times}8km^2$ and 15-day, respectively. Also the land cover map over East Asia is used. The noisy pixels are detected by the temporal continuity check with the reference values and dynamic threshold values according to season and location. In general, the number of noisy pixels are especially larger during summer than other seasons. And the detected noisy pixels are corrected by the iterative method until the noisy pixels are completely corrected. At first, the noisy pixels are replaced by the arithmetic weighted mean of two adjacent NDVIs when the two NDVI are normal. After that the remnant noisy pixels are corrected by the weighted average of NDVI of the same land cover according to the distance. After correction, the NDVI values and their variances are increased and decreased by 5% and 50%, respectively. Comparing to the other correction method, this correction method shows a better result especially when the noisy pixels are occurred more than 2 times consistently and the temporal change rates of NDVI are very high. It means that the correction method developed in this study is superior in the reconstruction of maximum NDVI and NDVI at the starting and falling season.

• Journal of the military operations research society of Korea
• /
• v.34 no.2
• /
• pp.79-101
• /
• 2008

This study is for improvement of repair part demand forecasting method of Republic of Korea Air Force aircraft. Recently, demand prediction methods are Weighted moving average, Linear moving average, Trend analysis, Simple exponential smoothing, Linear exponential smoothing. But these use fixed weight and moving average range. Also, NORS(Not Operationally Ready upply) is increasing. Recommended method of Box-Jenkins' ARIMA can solve problems of these method and improve estimate accuracy. To compare recent prediction method and ARIMA that use mean squared error(MSE) is reacted sensitively in change of error. ARIMA has high accuracy than existing forecasting method. If apply this method of study in other several Items, can prove demand forecast Capability.

• Journal of Welding and Joining
• /
• v.15 no.1
• /
• pp.81-91
• /
• 1997

In this study, a magnetic sensor to make use of eddy current was developed to detect the weld seam of butt joint in the sheet metal arc welding. This system consist of the sensor device for detecting the weld line, the servo control device for driving the weld torch movement and the control unit. A signal processing was applied to smooth the output signal of the sensor. The weld joint was determined by using a 1st order differential method. To improve tracking accuracy of the system, moving average method which has an effect of proportional and weighted integral control was applied to a series of the weld joint positions obtained above. The weld line for tracking was generated by using data regeneration algorithm. Based on these results, each servo motor was controlled by pulse generator. From experimental results, it was revealed that this system has excellent detecting ability for weld line and seam tracking ability.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.24-27
• /
• 1996

The storage function method(SFM) is one of hydrologic flood routings which has been used most widely in Korea and Japan. This paper presents a storage function method using multiple model adaptive estimation(MMAE), in which a model set is generated by partitioning storage parameters over feasible range, and each storage function model is estimated, and then the weighted average of them is calculated. Finally, the future runoff is predicted in real time by means of observed data of water level at dam and rainfall. Simulation results applied to actual data show that the proposed method has much better performance than that of conventional SFM.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.768-773
• /
• 2004

This work deals with the synthesis of discrete-time nonlinear controller for input time-delay existing nonlinear system and proposes a new effective method to compensate the influence of input time-delay. The controller is synthesised by using input/output linearization. Under the circumstance that input time-delay exist, controller have to produce future value that will be needed for system. On account of this reason described, a weighted average predictor of combined states is adopted. Using the discretization via Euler method, numerical simulations about Van der Pol system are performed to evaluate performance of the proposed method.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.7 no.10
• /
• pp.1-16
• /
• 1984

The purpose of this paper is to develop rational layout model for small and medium scale industry in Korea. The methodology of this paper is to light the importance of small and medium scale company. Moreover, to overcome the problem of layout in non-massing jobbing production shop this paper is proposed four techniques. So proposed layout model is obtained analytically in single, multiple facility location problem The result of this paper is as follows : First, alternatives to overcome abnormal layout in small and medium company are 1) GT (Group Technology) 2) SLP (Systematic Layout Planning) 3) OR (Operations Research) 4) Computer Second, in single facility location problem, Gradient method and square weighted average method are studied. Lastly in multiple facility location problem, heuristic method is obtained.

• ETRI Journal
• /
• v.36 no.4
• /
• pp.617-624
• /
• 2014

Through-silicon via (TSV) technology provides much of the benefits seen in advanced packaging, such as three-dimensional integrated circuits and 3D packaging, with shorter interconnection paths for homo- and heterogeneous device integration. In TSV, a destructive cross-sectional analysis of an image from a scanning electron microscope is the most frequently used method for quality control purposes. We propose a quantitative evaluation method for TSV etch profiles whereby we consider sidewall angle, curvature profile, undercut, and scallop. A weighted sum of the four evaluated parameters, nominally total score (TS), is suggested for the numerical evaluation of an individual TSV profile. Uniformity, defined by the ratio of the standard deviation and average of the parameters that comprise TS, is suggested for the evaluation of wafer-to-wafer variation in volume manufacturing.

• Journal of Integrative Natural Science
• /
• v.15 no.1
• /
• pp.1-8
• /
• 2022

In a multivariate normal production process N_p(µ,Σ), a chart combining three EWMA charts with accumulate-combine method for µ, variance components of Σ, and off-diagonal elements of Σ, into a EWMA (exponentially weighted moving average) chart is considered, which is called a combined EWMA chart. Through simulation work, the proposed combined EWMA chart's numerical performance and properties are examined. The simulation results show that the proposed combined EWMA chart, which is simultaneously monitoring all the process parameters of multivariate normal production process, works effectively in the perspective of means, variances and correlation coefficients. In addition, the combined EWMA chart is extended to VSI chart.