• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.6
• /
• pp.1161-1166
• /
• 2005

In this paper, for spatial multiplexing with limited feedback, we propose subspace based precoding in which the active bases are selected at the receiver from a finite number of basis sets known at both receiving and transmitting ends, conveyed to the transmitter using limited feedback, and assembled into a preceding matrix at the transmitter. The selected bases are conveyed to the transmitter using feedback information on both the index of a basis set, which indicates the most appropriate set of coordinates for describing a MIMO channel, and the active bases having the significant amounts of energy in the selected basis set. We show that the proposed subspace based precoding provides capacity similar to that of the closed-loop MIMO even with limited feedback.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.30 no.4
• /
• pp.545-558
• /
• 2020

The gaze-based input provides feedback to confirm that the typing is correct when the user types the text. Many studies have already demonstrated that feedback can increase the usability of gaze-based inputs. However, because the information of the typed text is revealed through feedback, it can be a target for shoulder-surfing attacks. Appropriate feedback needs to be used to improve security without compromising the usability of the gaze-based input using the original feedback. In this paper, we propose a new gaze-based input method, FFI(Fake Flickering Interface), to resist shoulder-surfing attacks. Through experiments and questionnaires, we evaluated the usability and security of the FFI compared to the gaze-based input using the original feedback.

• International Journal of Internet, Broadcasting and Communication
• /
• v.6 no.2
• /
• pp.1-9
• /
• 2014

This paper presents a study on nonlinear time varying systems based on differential geometry. A brief introduction about controllability and involutivity will be presented. As an example, the exact feedback linearization and the approximate feedback linearization are used in order to show some application examples.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.1
• /
• pp.138-141
• /
• 2011

This paper presents an LMI-based method to design an output feedback integral sliding mode controller for a class of uncertain systems. Using LMIs we derive an existence condition of a sliding surface. And we give a switching feedback control law. Finally, we give a numerical design example in order to show the effectiveness of the proposed method.

• Journal of Electrical Engineering and Technology
• /
• v.13 no.1
• /
• pp.493-500
• /
• 2018

This paper addresses a decentralized observer-based output-feedback formation control problem for multiple unmanned underwater vehicles (UUVs). The complex nonlinear model for a UUV is feedback-linearized. It is assumed that each UUV in the formation exploits only the information regarding itself and the immediate predecessor, which imposes structural constraints on the formation controller gain matrices. The design condition is presented as a two-stage linear matrix inequalities problem. The synthesized controller demonstrates its own advantages through a numerical example.

• Journal of Game and Entertainment
• /
• v.1 no.1
• /
• pp.15-22
• /
• 2005

Among recent technologies that are applied to game development, virtual reality part is getting much attention for its technological effectiveness in transmitting game processing circumstances in variety that are happening in game world very realistically. In this study we analyze interface for game that is based on a action realization technology and force-feedback technology among technologies for developing virtual reality, in other words, technical analogy on game controller and the positive and negative sides of game controller for each platform. Based on that, more ordinary and effective way to deliver the functions to users in PC game field where application of force-feedback technology is least satisfied. And, Force-Feedback seat has been developed to satisfy the users' needs by using vibration.

• Journal of the Semiconductor & Display Technology
• /
• v.7 no.4
• /
• pp.13-18
• /
• 2008

This paper explores a content-based image retrieval framework with relevance feedback based on genetic algorithm (GA). This framework adopts GA to learn the user preferences using the similarity functions defined for all available descriptors. The objective of the GA-based learning methods is to learn the user preferences using the similarity functions and to find a descriptor combination function that best represents the user perception. Experiments were performed to validate the proposed frameworks. The experiments employed the natural image databases and color and texture descriptors to represent the content of database images. The proposed frameworks were compared with the other two relevance feedback methods regarding effectiveness in image retrieval tasks. Experiment results demonstrate the superiority of the proposed method.

• ETRI Journal
• /
• v.38 no.2
• /
• pp.280-290
• /
• 2016

To implement high-order multiuser multiple input and multiple output (MU-MIMO) for massive MIMO systems, there must be a feedback scheme that can warrant its performance with a limited signaling overhead. The interference-to-noise ratio can be a basis for a novel form of Codebook (CB)-based MU-MIMO feedback scheme. The objective of this paper is to verify such a scheme's performance under a practical system configuration with a 3D channel model in various radio environments. We evaluate the performance of various CB-based feedback schemes with different types of overhead reduction approaches, providing an experimental ground with which to optimize a CB-based MU-MIMO feedback scheme while identifying the design constraints for a massive MIMO system.

• IEIE Transactions on Smart Processing and Computing
• /
• v.2 no.3
• /
• pp.160-167
• /
• 2013

Resource allocation based on quantized feedback plays a critical role in wireless mesh networks with a time division multiple access (TDMA) physical layer. In this study, a resource allocation problem was formulated based on quantized feedback for TDMA wireless mesh networks that minimize the total transmission power. Three steps were taken to solve the optimization problem. In the first step, the codebook of the power, rate and equivalent channel quantization threshold was designed. In the second step, the timeslot allocation criterion was deduced using the primal-dual method. In the third step, a resource allocation scheme was developed based on quantized feedback using the stochastic optimization tool. The simulation results show that the proposed scheme not only reduces the total transmission power, but also has the advantage of quantized feedback.

• Journal of Auto-vehicle Safety Association
• /
• v.12 no.4
• /
• pp.13-22
• /
• 2020

This paper presents an adaptive feedback based actuator fault detection and tolerant control algorithms for longitudinal functional safety of autonomous driving. In order to ensure the functional safety of autonomous vehicles, fault detection and tolerant control algorithms are needed for sensors and actuators used for autonomous driving. In this study, adaptive feedback control algorithm to compute the longitudinal acceleration for autonomous driving has been developed based on relationship function using states. The relationship function has been designed using feedback gains and error states for adaptation rule design. The coefficients in the relationship function have been estimated using recursive least square with multiple forgetting factors. The MIT rule has been adopted to design the adaptation rule for feedback gains online. The stability analysis has been conducted based on Lyapunov direct method. The longitudinal acceleration computed by adaptive control algorithm has been compared to the actual acceleration for fault detection of actuators used for longitudinal autonomous driving.