• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.7
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• pp.428-436
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• 2005

In this paper, we introduce an adaptive control method to improve the position accuracy and reduce nonlinear friction effects for the linear motion servo system with the nonlinear friction. The considered system plant included not only the variation of the mass of mover but also the friction change by the normal force. We also designed an adaptive controller with the mass estimator and the compensator by observing the variation of normal force. The effectiveness and system performances for the proposed control method in this paper show to improve than other control methods through numerical simulations.

• Macromolecular Research
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• v.10 no.6
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• pp.297-303
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• 2002

We have investigated the microstructural properties of a weakly charged polyelectrolyte modeled with both Hookean spring and Debye-Huckel potential, by employing a novel hybrid scheme of molecular dynamics (MD) and Monte Carlo (MC) simulations. Although the off-lattice pivot step facilitates the earlier computations stage, it gives rise to oscillations and hinders the stable equilibrium state. In order to overcome this problem, we adopt the MC off-lattice pivot step in early stage only, and then switch the computation to a pure MD step. The result shows that the computational speed-up compared to the previous method is entirely above 10 to 50, without loss of the accuracy. We examined the conformations of polyelectrolyte in solvents in terms of the end-to-end distance, radius of gyration, and structure factor with variations of the screening effects of solvent and the monomer charges. The emphasis can favorably be given on the elongation behavior of a polyelectrolyte chain, with observing the simultaneous snapshots.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.458-461
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• 2008

We carry out non-steady state finite element simulation of a porthole extrusion process for manufacturing a radiation pipe under isothermal assumption. It is assumed that welding takes place at the moment that the material contacts the plane of symmetry. Welding phenomena are revealed by observing the contacting mechanism of the material passed through the portholes. It is emphasized that mesh density control and intelligent remeshing during welding process govern the solution accuracy and the program applicability. AFDEX 3D is employed.

• Korean Journal of Geomatics
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• v.2 no.1
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• pp.1-6
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• 2002

Korea is a small country with relatively large mountainous areas and has many difficulties from planning to completing one road. Maintaining a completed road presents even more difficulties. presently, in estimating design elements, the result varies according to the engineer and there are many cases that question the reliability of the results. Therefore, in this study, the alignment of highway was sampled using by the centerline path, the design elements of horizontal alignment were reduced by applying the Least Squares Method, and the accuracy was analyzed. By this method, IP, IA, R, $\Delta$R and A-parameter were also determined. By observing relatively long straight sections, the approximate values could be estimated, and particularly, the considerably accurate value of A-parameter was determined. This study, using the Least Squares Method, aims to contribute to the development of the alignment examination in frequent traffic accident regions.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.113-118
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• 1989

By using the single mode optical fiber, we fabricated Fiber-optic Fabry-Perot interferometer (FFPI). The change over a wide range in the optical path length of a FFPI is observed. The temporal movement of the interference fringes by external condition to P.Z. T) is converted to circular motion on an oscilloscope display and then recorded with a micro-computer. The two output voltages of the D/A converters are applied to X and Y terminals of oscilloscope to display circular motion on oscilloscope. Thus the direction of phase shift can be determined with observing the direction of circular motion. The variation of the optical length can be measured by calculating the angle of spot of circle with an accuracy of λ/90 wave length due to variation of temperature in this system 2.7x10-4$^{\circ}C$.

• ETRI Journal
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• v.44 no.2
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• pp.327-338
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• 2022

Classification models for human action recognition require robust features and large training sets for good generalization. However, data augmentation methods are employed for imbalanced training sets to achieve higher accuracy. These samples generated using data augmentation only reflect existing samples within the training set, their feature representations are less diverse and hence, contribute to less precise classification. This paper presents new data augmentation and action representation approaches to grow training sets. The proposed approach is based on two fundamental concepts: virtual video generation for augmentation and representation of the action videos through robust features. Virtual videos are generated from the motion history templates of action videos, which are convolved using a convolutional neural network, to generate deep features. Furthermore, by observing an objective function of the genetic algorithm, the spatiotemporal features of different samples are combined, to generate the representations of the virtual videos and then classified through an extreme learning machine classifier on MuHAVi-Uncut, iXMAS, and IAVID-1 datasets.

• Journal of the Korea Society of Computer and Information
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• v.25 no.9
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• pp.1-9
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• 2020

In this paper, we propose a method of in-depth analysis of internal operation process by recording library calls and related information that occur in the operation process of NoSQL database. It observes and records the specified library calls, compares the internal behavior differences between the NoSQL databases through recorded library call information, and evaluates the characteristics and scalability of each database by observing changes in the number of input data. The development of computing performance and the activation of big data have led to the emergence of different types of NoSQL databases for recording and analyzing various and large amounts of data, and it is necessary to evaluate the scalability of each database in order to select a database suitable for each environment. However, it is difficult to analyze or predict how a database operates in traditional ways, such as benchmarking, observing external behavior through performance models, or analyzing structural features based on design. Therefore, it is necessary to utilize the techniques proposed in this paper to understand the scalability of NoSQL databases with high accuracy.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.485-493
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• 2019

With the development of remote sensing technology, it becomes possible to measure the trace gas concentration by satellites, so the ministry of environment is executing 152.5 billion-won to develop the geostationary orbital environment monitoring satellite and ground segment. A variety of contents for the application to utilize environmental satellite has been sought to increase the benefits. This study is for the improvement the accuracy of emission inventories, to correct emission amount with top-down method using the satellite observing data instead of bottom-up method. Two methodologies to estimate $NO_2$ emission were analyzed, one is ignoring $NO_2$ transportation effect(method-1), and the other is considering transportation effect(method-2) with source-receptor relationship equation, and the results were compared. The methodology of this study can be applicable all components which are observed from satellites.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.4
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• pp.123-131
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• 1983

It is a matter of great importance that the elements of error in measurements be minimized in various surveying methods. It is also essential in photogrammetry to reduce the errors of ground control coordinates as their influence on the accuracy of the results is enormous, especially when the object distance is increased. In this paper, the techniques of surveying and photogrammetry were appropriately combined to obtain three-dimentional coordinates of considerable accuracy. By observing only the related angles with theodolite were obtained to prove its effectiveness. The major advantage of the presented method is its simplicity and accuracy as only the measurements by theodolite is required.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.6
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• pp.63-74
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• 2005

In Electronic Commerce, the latest most of the personalized recommender systems have applied to the collaborative filtering technique. This method calculates the weight of similarity among users who have a similar preference degree in order to predict and recommend the item which hits to propensity of users. In this case, we commonly use Pearson Correlation Coefficient. However, this method is feasible to calculate a correlation if only there are the items that two users evaluated a preference degree in common. Accordingly, the accuracy of prediction falls. The weight of similarity can affect not only the case which predicts the item which hits to propensity of users, but also the performance of the personalized recommender system. In this study, we verify the improvement of the prediction accuracy through an experiment after observing the rule of the weight of similarity applying Vector similarity, Entropy, Inverse user frequency, and Default voting of Information Retrieval field. The result shows that the method combining the weight of similarity using the Entropy with Default voting got the most efficient performance.