• Journal of Broadcast Engineering
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• v.12 no.5
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• pp.516-524
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• 2007

In order to use limited frequency resources efficiently, a single frequency network using digital on-channel repeater(DOCR) has been studied and would be implemented. The DOCR generates strong pre-ghosts to ATSC DTV receivers. The forward filter of equalizer in ATSC DTV receivers compensates the distortion made by pre-ghosts. This process induces noise enhancement and colored noise, thereby results in the performance degradation. In this paper we propose to use a dual-feedback equalizer to combat strong pre-ghosts. The proposed equalizer has two feedback filters. One is the decision feedback filter and the other is non-decision feedback filter. The additional non-decision feedback filter decreases the noise by whitening the noise and preventing the generation of colored noise in pre-ghost channel. Thus the equalization technique of dual-feedback structure has performance enhancement in pre-ghost channel in comparison with conventional decision feedback equalizer(DFE). By simulation we analyzed the performance enhancements of DTV receiver using dual-feedback equalization structure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.3-4
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• 2009

As device process technology advances, effective channel length, the thickness of gate oxide, and supply voltage decreases. This paper describes a novel electrostatic discharge (ESD) protection device which has current feedback for high ESD immunity. A conventional Gate-Grounded NMOS (GGNMOS) transistor has only one ESD current path, which makes, the core circuit be in the safe region, so an GGNMOS transistor has low current immunity compared with our device which has current feedback path. To simulate our device, we use conventional $0.18\;{\mu}m$ technology parameters with a gate oxide thickness of $43\;{\AA}$ and power supply voltage of 1.8 V. Our simulation results indicate that the area of our ESD protection, device can be smaller than a GGNMOS transistor, and ESD immunity is better than a GGNMOS transistor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.49-52
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface contours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining processprohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normalto the face of the workpice can be filterd through an appropriate admittance transfer function to result in the estimated depth of cut. This can be compared to the desired depth of cut to generate the adjustment cotnrol action in addition to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. Based on the empirical data of the cutting dynamics, simulation results are shown.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.90-104
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• 2020

It is difficult for non-experts to build machine learning (ML) models at the level that satisfies their needs. Deep learning models are even more challenging because it is unclear how to improve the model, and a trial-and-error approach is not feasible since training these models are time-consuming. To assist these novice users, we examined how interactive and explainable feedback while training a deep learning network can contribute to model performance and users' satisfaction, focusing on the data preparation process. We conducted a user study with 31 participants without expertise, where they were asked to improve the accuracy of a deep learning model, varying feedback conditions. While no significant performance gain was observed, we identified potential barriers during the process and found that interactive and explainable feedback provide complementary benefits for improving users' understanding of ML. We conclude with implications for designing an interface for building ML models for novice users.

• Journal of IKEEE
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• v.27 no.4
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• pp.386-390
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• 2023

In this study, we examined the quasi-nonvolatile memory characteristics of silicon nanosheet (SiNS) feedback field-effect transistors (FBFETs) fabricated using a complementary metal-oxide-semiconductor process. The SiNS channel layers fabricated by photoresist overexposure method had a width of approximately 180 nm and a height of 70 nm. The SiNS FBFETs operated in a positive feedback loop mechanism and exhibited an extremely low subthreshold swing of 1.1 mV/dec and a high ON/OFF current ratio of 2.4×10⁷. Moreover, SiNS FBFETs represented long retention time of 50 seconds, indicating the quasi-nonvolatile memory characteristics.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.832-835
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• 1997

In this paper, we first analyze the structural limitation of the conventional PID controller in controlling unstable processes through mathematical proof. To overcome this structural limitation, we add an internal feedback loop to the PID controller. Secondly, we obtain conditions when unstable processes can be stabilized by a controller through an analytical analysis. Finally, we propose a simple on-line process identification and autotuning method for unstable processes. Many simulation results show that, in spite of its simplicity, the proposed on-line process identification method provides good accuracy in modeling the unstable process and acceptable robustness to measurement noises and disturbances. Also, the proposed autotuner shows good control performances for both servo and regulatory problems.

• English Language & Literature Teaching
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• no.3
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• pp.185-201
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• 1997

This study explores perspectives on responding to EFL students' compositions at the semantic level. In the last three decades, there has been a shift from product-oriented approach to process-oriented one to teaching writing. The shift has led to the criticism of the traditional view on teacher response. The traditional view has been under attack for its overemphasis upon form and ineffectiveness on improving student writing skill. It is also noted that research into students' reactions to the traditional teacher response has been inconclusive. The process-oriented approach, on the other hand, draws its attention to meaning and the logical development of thought as well as linguistic matters. In this context, the present study discusses what EFL teachers need to take into account in providing the semantic-level feedback on students' compositions. Firstly, teacher response to student writing is on-going; teacher feedback involves teacher intervention in the drafting process, the revision process, and the presentation of product. Secondly, in the writing conferences, the teacher provides students an opportunity to talk about writing, assistance and advice on the content/meaning of the written text, helping them expand and clarify thinking about audience(reader) and purpose.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.3
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• pp.137-143
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• 2002

This paper presents the In-process compensation to control cutter runout and improve the machined surface quality. Cutter runout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by compensation runout effect induced cutting force variation. This result will provide lots of information to build-up the preciswion machining technology.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.453-458
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• 2000

Design of an in-process feedback control system has been studied for precision grinding. A grinding system consists of a grinding tool, a turn table and a disk-shaped workpiece on the table is taken as an object. A grinding process model has been deduced which gives some reasoning about the process errors. In the control system the tool position is actively controlled by an electro-magnetic actuator in-process. The ground error is feedback to compose a closed-loop control system and an optimal PID controller is applied. Some control performances such as transient response and disturbance such as transient response and disturbance attenuation have been examined, which convinces the effectiveness of the control. Some methods for implementation of the control. Some methods for implementation of the control have been suggested from a standpoint of practical application.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.13-18
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• 2003

This paper presents the in-process compensation to control cutter ronout and to improve the machined surface quality. Cutter ronout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by cutter ronout compensation.