• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.319-322
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• 2005

This paper describes practical tuning methods and testing of a digital PSS, which uses both frequency and power, with the 220MVA Chungpyung P/P #1 in the KEPCO system to enhance the damping of local modes. In the first step, the objective phase of PSS is computed through a phase leading function to provide compensation between the exciter reference point and the generator air-gap torque before tuning the PSS's time constants. In addition, eigenvalue analysis was used to determine a range of PSS's gain, whichis the more useful for field testing rather than a single gain value. The Real-Time Digital Simulator was used to verify safe operations of the PSS in the presence of disturbances, such as AVR step and three phase fault.

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.152-157
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• 2009

In designing and manufacturing a submarine, an expensive real mock up is usually built as a reference because of the spatial constraints of a submarine. This paper presents an integrated and automated design process for a submarine that uses a digital mock up. Various equipment libraries are built for feature based design. Using the developed digital mock up, this paper shows various ways to verify the design, including a space analysis to check for any interference between pieces of equipment and the hull and an ergonomic analysis using lifelike dummies to examine the work space and operability. As a part of the integrated design system, a design automation system was also developed to generate surface point data for the outer hull, pressure hull, casing, and sail. The whole process was applied to the design of a submarine for verification.

• Proceedings of the Korea Contents Association Conference
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• 2005.11a
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• pp.335-339
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• 2005

Digital elevation models(DEM) were generated from SPOT-5 HRG supermode imagery through photogrammetric processing. The reference DEMs were obtained from digital topographic maps of 1/5000 scaleas for analyzing the accuracy of the generated DEMs. The DEMs extracted from HRG stereo image data were compared with digital topograpic map DEMs on several test sections. And digital surface models(DSM) and 3D building model was produced.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.314-320
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• 2005

In this paper, a methodology for estimating the parameters of a discrete-time system and designing a digital PID controller based on the estimated model and a genetic algorithm is presented. To deal with optimization problems occurring regarding parameter estimation and controller design, a pseudo parallel genetic algorithm (PPGA) is used. The parameters of a discrete-time system are estimated using both the model technique and a PPGA. The digital PID controller is described by the pulse transfer function and its parameters are tuned based on both the model reference technique and another PPGA. A set of experimental works on two processes are carried out to illustrate the performance of the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.2043-2054
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• 1996

In this paper, Digital Delay Locked Loop(DDLL) is designed, implemented and analysed by experiment whose results show that it is possible to track the received signal by this scheme. Designed digital DLL has an advantage that it is not needed to maintain gain balance between early and late channels, which has been problem with an analog DLL. Also DDLL has more improved noise performance compared to analog DLL due to noise level limitation and noise cancellation characteristics. For various loop parameters, their effects on loop performance are analysed and simulated. Proposed DDLL is the first attempt as a digital approach in code tracking loop and it is expected to be a good reference for spread spectrum communication research.

• Current Optics and Photonics
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• v.2 no.6
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• pp.547-553
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• 2018

In this paper, a new method for spatial filtering in digital holography is proposed and verified by simulations compared to conventional methods. The new method is based on the simultaneous acquisition of two digital holograms, which can be separated by distinct spatial modulation, in a single image. Two holograms are generated by two reference waves, which have different spatial modulation orientations. Then, the overlapping region between the DC term and the object wave in the first hologram can be replaced with a less-overlapping region of the object wave in the second hologram because the whole image contains two holograms where the same objective wave has been recorded. In the simulation results, it is confirmed that the reconstructed image by the new method has better quality than for the original method.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.10-18
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• 2022

Since High Sierra, APFS has been used as the main file system. It is a well-established file system that has been used stably thus far. From the perspective of digital forensics, there are still many areas to be investigated. Apple File System Reference is provided to the apple developer site, but it is not satisfactory to fully analyze APFS. Researchers know more about the structure of APFS than before, but they have not yet fully analyzed its structure to a perfect level about it. In this paper, we develop APFS object identification tool for digital forensics. The most basic and essential object identification and analysis of the APFS filesystem will be conducted with the tool. The analysis in this study serves as the background for an analysis of the checkpoint operation principle and structure, including the more complex B-tree structure of APFS. There are several options for the developed tool, but the results of two use cases will be shown here. Based on the implemented tool, it is hoped that more functions will be added to make APFS a useful tool for faster and more accurate analyses.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.21-30
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• 2023

The aim of this study is to investigate how travelers' destination visit intentions are influenced by avatar self-congruence in the metaverse platform. We extended the impression management theory by considering both perceived enjoyment and social engagement, and illustrated the interaction effect based on users' digital age. To achieve this, we conducted an online survey with 302 users. The survey results revealed that avatar self-congruence significantly influenced users in terms of perceived enjoyment and social engagement, thereby affecting their destination visit intentions. This study also revealed a significant interaction effect between digital age type and avatar self-congruence on users' perceived enjoyment. The results of this study are expected to provide not only a theoretical reference for metaverse research and travel research but also managerial implications for destination management and metaverse applications.

• Journal of the Korean Society of Costume
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• v.64 no.6
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• pp.120-130
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• 2014

The present study aimed to find out the most effective instructional method for illustration to aid the $21^{st}$-century post digital generation learners in their education. Although the literature discusses government-led enactment and revision of educational policy and curriculums and research reports by the Ministry of Education and other government agencies as well as many other research articles deal with futuristic instructional methods, the instructional methods in practice have not fully changed yet. Illustration is a means of visual communication and a subject that best represent 'expressionism' and 'speed' of the post digital generation. The present study exemplifies instructional methods to establish the need for lesson plans that best suit individuality of students and for re-training instructors. Also, the feedback process with students proved that the post digital generation learned Photoshop quickly and improved creativity via image synthesis even in short-term instructions. The present findings can be possibly used as reference data for instructional methods for illustration using digital media that best suits learners of the post digital generation. This being said, further studies should delve into specific instructional methods.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.265-273
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• 2014

In this paper, context-aware technologies using a Kinect sensor for a digital signage which is increasingly growing as the 4th screen media is presented. Generalized context-aware functions for a digital signage were studied and a context-aware digital signage platform was developed. It can support a natural user interface for controlling a digital signage and actively provide contents adapted to its context. As a basic context, user's gesture and voice, the number of users, sound direction were considered. In the future, the advanced functions such as age, gender will be studied. The implemented platform could be a good reference model when developing a general context-aware digital signage.