• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.2068-2086
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• 2011

Based on the quincunx sub-sampling grid, the New Interleaved Hierarchical INTerpolation (NIHINT) method is recognized as a superior pyramid data structure for the lossless and progressive coding of natural images. In this paper, we propose a new image interpolation algorithm, Edge Adaptive Hierarchical INTerpolation (EAHINT), for a further reduction in the entropy of interpolation errors. We compute the local variance of the causal context to model the strength of a local edge around a target pixel and then apply three statistical decision rules to classify the local edge into a strong edge, a weak edge, or a medium edge. According to these local edge types, we apply an interpolation method to the target pixel using a one-directional interpolator for a strong edge, a multi-directional adaptive weighting interpolator for a medium edge, or a non-directional static weighting linear interpolator for a weak edge. Experimental results show that the proposed algorithm achieves a better compression bit rate than the NIHINT method for lossless image coding. It is shown that the compression bit rate is much better for images that are rich in directional edges and textures. Our algorithm also shows better rate-distortion performance and visual quality for progressive image transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.320-327
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• 2005

In this paper, compensation structures are proposed in the CPW directional couplers with finite-extent backed conductor for tight coupling. The proposed structures are realized T-shaped expanded slots and modified finite-extent backed conductor in CPW coupled structure. The T-shaped expanded slots was used to avoide reduced coupling and modified finite extent backed conductor of dumbbell shape was used to enhance directivity and matching. The designed CPW directional couplers at 1 GHz has good directivity without reducing coupling in simulation by EM solver based on full-wave analysis and measurements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.3
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• pp.172-179
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• 2013

In this paper, we consider network-coded bi-directional relaying (NCBR) schemes over an asymmetric channel, in which bi-directional links have the different channel quality, as well as the asymmetric traffic load. In order to deal with asymmetric nature, two different types of NCBR schemes are considered: network coding after padding (NaP) and network coding after fragmentation (NaF). Even if NaP has been known as only a useful means of dealing with the asymmetry in traffic load up to now, our analysis shows that its gain can be significantly lost by the asymmetry in channel quality, under the given bit error performance constraint. Furthermore, it is shown that NaF always outperforms NaP, as well as traditional bi-directional relaying scheme.

• Journal of information and communication convergence engineering
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• v.11 no.1
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• pp.56-61
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• 2013

Modern integrated circuits (ICs) are becoming an integrated parts of analog, digital, and radio frequency (RF) circuits. Testing these RF circuits on a chip is an important task, not only for fabrication quality control but also for tuning RF circuit elements to fit multi-standard wireless systems. In this paper, RF test circuits suitable for embedded testing are introduced: RF power detectors, power control circuits, directional couplers, and six-port reflectometers. Various types of embedded RF power detectors are reviewed. The conventional approach and our approach for the RF power control circuits are compared. Also, embedded tunable active directional couplers are presented. Then, six-port reflectometers for embedded RF testing are introduced including a 77-GHz six-port reflectometer circuit in a 130 nm process. This circuit demonstrates successful calibrated reflection coefficient simulation results for 37 well distributed samples in a Smith chart. The details including the theory, calibration, circuit design techniques, and simulations of the 77-GHz six-port reflectometer are presented in this paper.

• Journal of the Korea Society of Computer and Information
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• v.28 no.12
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• pp.97-104
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• 2023

In this paper, we propose a harmful bird repellent system using directional speakers. Existing sound systems for the extermination of harmful birds have the disadvantage of reducing effectiveness due to the learning effect of birds due to problems caused by noise pollution and monotonous sounds. In this paper, directional speakers are used to minimize surrounding noise. In addition, the up-down and left-right angles of the speaker driving device were freely adjusted to maximize usability. Additionally, the problem of performance degradation due to learning effects was solved by using various scanning patterns. In the future, we plan to develop a platform capable of central control by applying remote control functions and a deep learning model that can recognize bird species.

• Journal of Information Processing Systems
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• v.13 no.3
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• pp.435-447
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• 2017

Associative and bidirectional associative memories are examples of associative structures studied intensively in the literature. The underlying idea is to realize associative mapping so that the recall processes (one-directional and bidirectional ones) are realized with minimal recall errors. Associative and fuzzy associative memories have been studied in numerous areas yielding efficient applications for image recall and enhancements and fuzzy controllers, which can be regarded as one-directional associative memories. In this study, we revisit and augment the concept of associative memories by offering some new design insights where the corresponding mappings are realized on the basis of a related collection of landmarks (prototypes) over which an associative mapping becomes spanned. In light of the bidirectional character of mappings, we have developed an augmentation of the existing fuzzy clustering (fuzzy c-means, FCM) in the form of a so-called collaborative fuzzy clustering. Here, an interaction in the formation of prototypes is optimized so that the bidirectional recall errors can be minimized. Furthermore, we generalized the mapping into its granular version in which numeric prototypes that are formed through the clustering process are made granular so that the quality of the recall can be quantified. We propose several scenarios in which the allocation of information granularity is aimed at the optimization of the characteristics of recalled results (information granules) that are quantified in terms of coverage and specificity. We also introduce various architectural augmentations of the associative structures.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.8
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• pp.795-800
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• 2014

In this paper, a vibrotactile pad system, T-mobile, is developed to provide vibrotactile cues for hand-held devices. A grooved and slim design is adapted to the back-side plane of the T-mobile, and the contact part consists of 12 vibrotactile panels which can operate independently and separately. To be isolated among vibrotactile actuators, the surface of the cover is divided into several pieces. Each vibrating module consists of a linear resonant actuator, a section of covering surface, and a vibration isolator. In order to provide spatial and directional information, sensory saltation and phantom sensation are applied to the T-mobile. To evaluate the developed device, two experiments were conducted to test whether directional information and spatial information can be successfully displayed by the device. Additionally, in order to find optimal stimulation by sensory saltation, an empirical test was conducted. As a result, spatial and directional information would be useful for displaying intuitive information for hand-held devices with vibrotactile feedback and reasonable near-optimal value for sensory saltation was obtained.

• Journal of Information Processing Systems
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• v.1 no.1 s.1
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• pp.96-101
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• 2005

Spotlighted as an innovative information technology environment, ubiquitous computing has been actively researched on recently. Especially, domestic and global researches focus on the RFID system, which is being eyed to replace the existing bar-code system. As an essential technology for ubiquitous computing, the RFID system can be applied for various purposes. The security issues of the RFID system focus on how the low-priced tag type could have reasonable price competitiveness. The Auto-ID Center in the U.S. is spearheading the research on distribution service and omni-directional security. As for Japan, the researches on omni-directional security and EPC application are necessary in securing the technology for ubiquitous computing with support from the Ministry of Public Management Home Affairs, Posts, and Telecommunication. In this paper, a method of ensuring the availability of the RFID system service will be presented based on the ubiquitous computing environment with the existing omni-directional security and user-friendly interface. While the existing researches focus on the RF reader system and tag-based security, this paper's suggestion also considers the availability of a sen ice to suggest ways of increasing the practical usage of a low-priced RF tag.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.7-10
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• 2005

Ad hoc MAC protocols using directional antennas can be used to improve the network capacity. Directional antennas have a Deafness problem and decrease throughput of the network caused by increasing backoff duration. Dual channel protocols have been proposed to mitigate the Deafness and hidden node problems. In this paper, we propose a dual channel MAC protocol using a directional antenna to mitigate the Deafness problem and increase the network capacity. The performance of the proposed Ad hoc MAC protocol is confirmed by computer simulations using Qualnet ver. 3.8 simulator.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.2
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• pp.93-101
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• 2014

Underwater radiated noise is the key in acoustic stealth performance of modern naval ships. The underwater radiated noise predicted by the hull vibration with radiation efficiency cannot always give the information of radiation pattern which is essential to analyze of detection probability by enemy and to improve the operational performance of the naval ship. The radiation pattern of underwater radiated noise is able to be obtained with radiation efficiency and radiation directional coefficient. In this paper, a new method to extract the radiation efficiency and radiation directional coefficient is suggested and proved with the simulation and experiment by using cylindrical shell of 70 cm diameter in air.