• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1411-1417
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• 2009

In this paper, we consider the design of $H_{\infty}$ control of linear discrete-time systems having no mathematical model. The basic approach is to use Q-learning which is a reinforcement learning method based on actor-critic structure. The model-free control design is to use not the mathematical model of the system but the informations on states and inputs. As a result, the derived iterative algorithm is expressed as linear matrix inequalities(LMI) of measured data from system states and inputs. It is shown that, for a sufficiently rich enough disturbance, this algorithm converges to the standard $H_{\infty}$ control solution obtained using the exact system model. A simple numerical example is given to show the usefulness of our result on practical application.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.33.2-33
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• 2001

The robust stability condition for sampled-data control systems with a sector nonlinearity was presented in our previous paper. Although it is applicable only to the sampled-data control system of a certain class, a usual discretetime control system can belongs to this type of class. This paper analyzes the amplitude dependent behavior of nonlinear sampled-data (i.e., discrete-time) control systems in a frequency domain. By considering restricted areas (sectors) in the nonlinear characterisitic, the existence of a sustained oscillation is estimated, and the relationship between the stable/unstable conditions and the result derived from describing function is compared. Based on these considerations, the stabilization of nonlinear discrete-time control systems is examined in the frequency domain.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1823-1826
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• 2002

On modern computer culture, the high quality data is required in multimedia systems. So, the technology of data compression fur data transmission is necessary now. This paper presents the pipeline architecture for the low and column address generator of 2D DCT/IDCT (Discrete Cosine Transform/Inverse Discrete Cosine Transform. In the proposed architecture, the area of hardware is reduced by using the DA (distributed arithmetic) method and applies the concepts of pipeline to the parallel architecture. As a result the designed pipeline of the low and column address generator for 2D DCT/IDCT architecture is implemented with an efficiency and high speed compared with the non-pipeline architecture.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.157-160
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• 1996

Physical systems axe generally continuous-time in nature. However as the data measured from these systems is generally in the form of discrete samples, and most modern signal processing is performed in the discrete-time domain, discrete-time models are employed. This paper describes methods for estimating the coefficients of continuous-time system within a closed loop control system. The method employs a recursive estimation algorithm to identify the coefficients of a discrete-time bilinear-operator model. The coefficients of the discrete-time bilinear-operator model closely approximate those of the corresponding continuous-time Laplace transform transfer function.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.315-318
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• 2008

Numerical calculation for the 1MW class horizontal axis wind turbine blade has been carried out to estimate the magnitude between discrete noise and random noise. Farassat formula 1A was adopted to get the discrete noise signal, and blade element momentum theory was used to obtain the distribution of the aerodynamic data along the blade span. Fukano's approach was also adopted to calculate the unsteady aerodynamic random noise due to the Karman vortex generation at the trailing edge of the wind turbine blade. From the noise prediction for the 1MW class horizontal axis wind turbine, the frequency band of the discrete noise lies in the infrasound region, and that of the random noise lies in the audible band region.

• Journal of Computational Design and Engineering
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• v.1 no.4
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• pp.233-242
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• 2014

A magnetically levitated vehicle (Maglev) system is under commercialization as a new transportation system in Korea. The Maglev is operated by an unmanned automatic control system. Therefore, the plan of train operation should be carefully established and validated in advance. In general, when making a train operation plan, statistically predicted traffic data is used. However, a traffic wave often occurs in real train service, and demand-driven simulation technology is required to review a train operation plan and service quality considering traffic waves. We propose a method and model to simulate Maglev operation considering continuous demand changes. For this purpose, we employed a discrete event model that is suitable for modeling the behavior of railway passenger transportation. We modeled the system hierarchically using discrete event system specification (DEVS) formalism. In addition, through implementation and an experiment using the DEVSim++ simulation environment, we tested the feasibility of the proposed model. Our experimental results also verified that our demand-driven simulation technology can be used for a priori review of train operation plans and strategies.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.257-263
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• 2011

There are many previous researches such as verification of accuracy, application, and change detection of discrete return LiDAR data, but no researches for full waveform LiDAR data. In this study, we selected the forest area and urban area as case study areas and compared the height accuracy of full waveform LiDAR data with field surveying data. As a result, we got an RMSE of 3.lcm in urban area, 4.7cm in forest area, and it is verified that height accuracy of full waveform LiDAR is high. We think that it is very usefull in aerial photogrammetry.

• ETRI Journal
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• v.39 no.5
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• pp.672-682
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• 2017

Video compression exploits statistical, spatial, and temporal redundancy, as well as transform and quantization. In particular, the transform in a frequency domain plays a major role in energy compaction of spatial domain data into frequency domain data. The high efficient video coding standard uses the type-II discrete cosine transform (DCT-II) and type-VII discrete sine transform (DST-VII) to improve the coding efficiency of residual data. However, the DST-VII is applied only to the Intra $4{\times}4$ residual block because it yields relatively small gains in the larger block than in the $4{\times}4$ block. In this study, after rearranging the data of the residual block, we apply the DST-VII to the inter-residual block to achieve coding gain. The rearrangement of the residual block data is similar to the arrangement of the basis vector with a the lowest frequency component of the DST-VII. Experimental results show that the proposed method reduces the luma-chroma (Cb+Cr) BD rates by approximately 0.23% to 0.22%, 0.44% to 0.58%, and 0.46% to 0.65% for the random access, low delay B, and low delay P configurations, respectively.

• Kyungpook Mathematical Journal
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• v.47 no.4
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• pp.601-608
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• 2007

In this paper we introduce a discrete model of brucellosis happened in Korean livestock farms and numerically analyze its dynamical features. To do it, we consider parameters data supported by Livestock Cooperatives. To control brucellosis, we investigate the relationship among key parameters, as applications of our model. We hope that our model may be used to reduce brucellosis in Korean livestock farms.

• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.43-47
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• 2000

We studied experimentally a discrete random phase-code multiplexing technique for holographic data storage, which we believe can overcome some disadvantages of conventional random phase-code multiplexing adopting either a diffusion plate or a multimode fiber. Experimental demonstration is presented to show the potential usefulness and some characteristics of the discrete random phase-code multiplexing technique.