• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.231-234
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• 2004

Chemical mechanical polishing(CMP) process was studied in terms of tribology in this paper. CMP performed by the down force and the relative motion of pad and wafer with the slurry is typically tribological system composed of friction, wear and lubrication. The piezoelectric quartz sensor for friction force measurement was installed and the friction force was detected during CMP process. Various coefficient of friction was attained and analyzed with the kind of pad, abrasive and the abrasive concentration. The lubrication regime is also classified with ${\eta}v/p(\eta,\;v\;and\;p;$ the viscosity, relative velocity and pressure). Especially, the co-relation not only between the friction force and the removal per unit distance but also between the coefficient of friction and within-wafer-nonuniformity was estimated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3041-3063
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• 2018

Community search aims at finding a meaningful community that contains the query node and also maximizes (minimizes) a goodness metric. This problem has recently drawn intense research interest. However, most metric-based algorithms tend to include irrelevant subgraphs in the identified community. Apart from the user-defined metric algorithm, how can we search the natural community that the query node belongs to? In this paper, we propose a novel community search algorithm based on the concept of the k-hop and local distance dynamics model, which can naturally capture a community that contains the query node. The basic idea is to envision the nodes that k-hop away from the query node as an adaptive local dynamical system, where each node only interacts with its local topological structure. Relying on a proposed local distance dynamics model, the distances among nodes change over time, where the nodes sharing the same community with the query node tend to gradually move together, while other nodes stay far away from each other. Such interplay eventually leads to a steady distribution of distances, and a meaningful community is naturally found. Extensive experiments show that our community search algorithm has good performance relative to several state-of-the-art algorithms.

• Journal of Welding and Joining
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• v.16 no.3
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• pp.55-63
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• 1998

Among the position sensing methods available, the arc sensor which utilizes the electrical signal obtained from the welding arc itself is one of the most prevalently used methods, because it has an advantage that no particular sensing device is necessary and real-time sensing of a groove position is possible directly under the arc. The authors have already developed a seam tracking system that contains a new arc sensor algorithm, which uses the relative welding current variation according to the tip-to-workpiece distance in GMA welding. In this study a torch height control algorithm for automatic weld seam tracking was proposed for completing the previous system, which uses an on-off control technique. To implement the torch height control algorithm during weld seam tracking the system parameters which include 2nd averaging range, weighting factor for 2nd moving averaging, and Z-directional basic compensation distance were determined by experimental analysis. Finally the two different height control methods, one is simple on-off control and the other on-off control using a reference current value , were compared in their tracking abilities.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.3
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• pp.507-513
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• 2008

In this study, we develope an ambulatory ECG acquisition system by implementing a patch-style and wireless electrode. To alleviate the inherent noisy characteristics of the mobile signal, we apply a matched filter and concurrently detect R-peak values. Moreover, the measure for resolving shape distance is computed to estimate the relative similarity between two ECG signals and to decide whether the abnormal characteristics in ECG exist or not.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.2
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• pp.119-124
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• 2016

According to the expansion of smartphone penetration and development of wearable device, personal context information can be easily collected. To use this information, the context aware recommender system has been actively studied. The key issue in this field is how to deal with the context information, as users are influenced by different contexts while rating items. But measuring the similarity among contexts is not a trivial task. To solve this problem, we propose context aware post-filtering to apply the context compensation. To be specific, we calculate the compensation for different context information by measuring their average. After reflecting the compensation of the rating data, the mechanism recommends the items to the user. Based on the item recommendation list, we recover the rating score considering the context information. To verify the effectiveness of the proposed method, we use the real movie rating dataset. Experimental evaluation shows that our proposed method outperforms several state-of-the-art approaches.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.3
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• pp.130-135
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• 2001

In this paper, an observer-based adaptive controller is proposed to control the longitudinal motion of vehicles. The standard gradient method will be used to estimate the vehicle parameters, mass, time constant, etc. The nonlinear model between the driving force and the vehicle acceleration will be chosen to design the state observer for the vehicle velocity and acceleration. It will be shown that the proposed observer is exponentially stable, and that the adaptive controller proposed on this paper is stable. It will be proved that the errors of the relative distance, velocity and acceleration converge to zero asymptotically fast, and that the overall system is also asymptotically stable. The simulation results are presented to investigate the effectiveness of the proposed method.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.297-302
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• 2009

In this paper, we propose advanced screen detector as a tool for selecting the object for tracking and estimating its distance from a screen using fuzzy logic in vision based pointing device. Our system classifies the line component of the input image into horizontal and vertical lines and applies the fuzzy rule to obtain the best line pair which constitute peripheral framework of the screen. The proposed system improves the detection ratio for detecting the screen in relative to the detector used in the previous works for hand-held type vision based pointing device. Also it allows to detect the screen even though a small part of it may be hidden behind other object.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.11
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• pp.527-531
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• 2006

Since 1996, KEPCO has been operating a wide range lightning detection system, LPATS, and been accumulating relative application techniques and statistical analysis skills. So, KEPRI already has its own basis to develope more accurate advanced detection technology and references to do comparative study. For three-dimensional imaging of lightning channels, UHF/VHF antenna systems were installed at 2 sites. The distance between two sites is about 30 km. These systems were used the AOA(Angle of Arrival) methods for lightning detection. In this paper, we would like to introduce about our system and its results.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.6
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• pp.1010-1019
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• 1994

It is shown that there exists a nonlinear mapping which transforms image features and their changes to the desired camera motion without measuring of the relative distance between the camera and the object. This nonlinear mapping can eliminate several difficulties occurring in computing the inverse of the feature Jacobian as in the usual feature-based visual feedback control methods. Instead of analytically deriving the closed form of this mapping, a Fuzzy Membership Function-based Neural Network (FMFNN) incorporating a Fuzzy-Neural Interpolating Network is used to approximate the nonlinear mapping. Several FMFNN's are trained to be capable of tracking a moving object in the whole workspace along the line of sight. For an effective implementation of the proposed FMF network, an image feature selection process is investigated. Finally, several numerical examples are presented to show the validity of the proposed visual servoing method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.9-13
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• 1995

In this paper, Zinc Oxide films, with a high degree of c-axis orientation, have been grown on glass substrates by a rf magnetron sputtering. The maximum crystal orientation was found to occur with substrate temperature 150$^{\circ}C$, input power 190W, oxygen rate 50%, target-substrate distance 55mm. It is proposed to achieve high-resistivity ZnO films by increasing the annealing temperature. The piezoelectric layers, preferred oriented with (002) perpendicular to the layer with 4.9$^{\circ}$, could be obtained by the annealing temperature 300$^{\circ}C$ in oxygen atmosphere. It is indicated that the relative permittivity is range from 8.9 to 9.8 in the frequency ranging from 10KHz to 5MHz.