• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.256-264
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• 2010

In this paper, a digital controller of magnetic bearing system for a high vacuum turbomolecular pump (TMP) is designed and examined. For stabilizing and providing damping in magnetic bearing, the digital PID controller is applied for each 5 control axes, and the inter-axis cross feedback controller is also applied to suppress low frequency vibration caused by gyroscopic moment of the rotor at high speed of rotation. The fabricated rotor-shaft has its first flexible natural frequency lower than maximum speed, about 614Hz, so the two lead filters are applied to increase damping of flexible mode. Notch filters with rotating frequency were selected to reduce vibration of the pump housing caused by unbalance load. The implemented controllers are verified by examination of frequency response and rotating test up to 40,000 rpm, which is higher than critical speed of backward flexible mode.

• The Research Journal of the Costume Culture
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• v.15 no.5
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• pp.796-809
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• 2007

The viewpoint of growth pursuit is changed to that of life quality's and happiness' pursuit by modern people. Modern people in digital environment, tired of fast-changing and oppressive daily life, prefer well-being trend providing tranquility and relaxation. Well-being is related to digital, because negative influences of digital lead human-oriented, environment-friendly well-being design. Therefore the purpose of this study is to research and analyze the relation of well-being fashion design and digital environment through case study in contemporary well-being fashion design. The results of this study are as follows: 1. This study shows that the attributes of digital environment make up function-intensive, interactivity, mobility & nomad, human & emotion-oriented and environment-friendly. And this study shows the design characteristics of digital environment consist of function-intensive design by digital convergence, open structure design for interactivity, modular design for mobility & nomad, emotion-oriented & multi-sensory design and environment- friendly design. 2. Function-intensive design in modem well-being fashion composed of vogue of caports style(casual+sports), practical use of multi-functional new-healthy textiles, and popularity of many style's mixture at once. Open structure design consist of wrapover design, use of transparent materials. Modular design are layered styling, practical use of zipper and velcro. Emotion-oriented & multi-sensory design are constitute of fad of wrinkle materials, application of bright & vivid tone, personal color and family look. Environment-friendly design in contemporary well-being fashion are comprised in use of natural color, re-advent of natural floral motif and eco-design.

• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.854-865
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• 2014

This paper proposes a method to generate a stereoscopic image pair from a digital hologram by considering the situation that digital hologram data is serviced but the end-user does not have the proper display equipment, etc. We use Fresnel transform as the method to convert a digital hologram into an image. Each image of the stereoscopic image pair uses a part of the given digital hologram and the sizes of the two partial digital holograms for the two images are chosen to be the same. Here, the size of the image is adjusted by the size of the partial digital hologram and the disparity between the pair images is adjusted by the distance between the centers of the two partial hologram. This paper also deals with how to adjust the size and the disparity of the images. In this paper the generated stereoscopic images are implemented as an anaglyphic display type to confirm the feeling of distance by wearing the red-blue glasses.

• Journal of the Korean Society for information Management
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• v.19 no.3
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• pp.211-326
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• 2002

This study is to analyze and evaluate copyright protection environment in digital reproduction and transmission, find out problems involved. and suggest recommendations for improvement. Data was collected 50 libraries to which digital reproduction and transmission is permitted under the Copyright Act were surveyed to examine the present states of digitalization and the systems employed. Also, library users, sampled from 5 libraries carrying out all the 6 technical measures obliged by the Copyright Act, were surveyed to examine their use of digital materials and perception on the copyright. After reviewing descriptive statistics, frequency and cross-tabulation analysis were made. The results of the analysis are most of the libraries. except for the industry university libraries, have implemented digital library systems, but the introduction rate of both digital reproduction system and transmission system are high (68.0% and 84.0%. respectively), while that of copyright protection system was low (26.0%). 84.0% of the libraries surveyed digitalize the full text, but the Libraries have digital collection less than 5,000 items, and only 33.3% of them digitalize materials with securing the copyrights. Regulations on copyright protections are not obliged properly. and it appeared that not only users' perception and perception of copyright as well as their use of electronic books are relatively low.

• Journal of The Korean Association of Information Education
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• v.20 no.2
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• pp.189-196
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• 2016

The PATROL instructional model only uses digital textbooks. PATROL is an acronym for Planning, Action, Tracking, Recommending, Ordering, and Leading. Teachers have a difficult time using current digital textbooks to determine how much time students spend using course materials. This is because current digital textbooks can only show the content of paper textbooks and display additional multimedia materials. In this study, digital textbook functions were designed based on the PATROL model in order to analyze students' learning situations, diagnose problems, and offer solutions. Digital textbook are based on learning analytics named SEE-PAD. SEE-PAD is composed of the following: Social network analysis; Evaluation and assEssment analysis; Predictive analysis; Adaptive learning analysis; and the analysis Dashboard. I drew and showed the use case and sequence diagrams of SEE-PAD to help design digital textbook functions.

• Imaging Science in Dentistry
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• v.42 no.3
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• pp.163-167
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• 2012

Purpose: ANSI/ADA has established standards for adequate radiopacity. This study was aimed to assess the changes in radiopacity of composite resins according to various tube-target distances and exposure times. Materials and Methods: Five 1-mm thick samples of Filtek P60 and Clearfil composite resins were prepared and exposed with six tube-target distance/exposure time setups (i.e., 40 cm, 0.2 seconds; 30 cm, 0.2 seconds; 30 cm, 0.16 seconds, 30 cm, 0.12 seconds; 15 cm, 0.2 seconds; 15 cm, 0.12 seconds) performing at 70 kVp and 7 mA along with a 12-step aluminum stepwedge (1 mm incremental steps) using a PSP digital sensor. Thereafter, the radiopacities measured with Digora for Windows software 2.5 were converted to absorbencies (i.e., A=-log (1-G/255)), where A is the absorbency and G is the measured gray scale). Furthermore, the linear regression model of aluminum thickness and absorbency was developed and used to convert the radiopacity of dental materials to the equivalent aluminum thickness. In addition, all calculations were compared with those obtained from a modified 3-step stepwedge (i.e., using data for the 2nd, 5th, and 8th steps). Results: The radiopacities of the composite resins differed significantly with various setups (p<0.001) and between the materials (p<0.001). The best predicted model was obtained for the 30 cm 0.2 seconds setup ($R^2$=0.999). Data from the reduced modified stepwedge was remarkable and comparable with the 12-step stepwedge. Conclusion: Within the limits of the present study, our findings support that various setups might influence the radiopacity of dental materials on digital radiographs.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.145-151
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• 2013

Purpose: This study was performed to evaluate and compare the radiopacity of dentin, enamel, and 8 restorative composites on conventional radiograph and digital images with different resolutions. Materials and Methods: Specimens were fabricated from 8 materials and human molars were longitudinally sectioned 1.0 mm thick to include both enamel and dentin. The specimens and tooth sections were imaged by conventional radiograph using #4 sized intraoral film and digital images were taken in high speed and high resolution modes using a phosphor storage plate. Densitometric evaluation of the enamel, dentin, restorative materials, a lead sheet, and an aluminum step wedge was performed on the radiographic images. For the evaluation, the Al equivalent (mm) for each material was calculated. The data were analyzed using one-way ANOVA and Tukey's test (p<0.05), considering the material factor and then the radiographic method factor, individually. Results: The high speed mode allowed the highest radiopacity, while the high resolution mode generated the lowest values. Furthermore, the high resolution mode was the most efficient method for radiographic differentiation between restorative composites and dentin. The conventional radiograph was the most effective in enabling differentiation between enamel and composites. The high speed mode was the least effective in enabling radiographic differentiation between the dental tissues and restorative composites. Conclusion: The high speed mode of digital imaging was not effective for differentiation between enamel and composites. This made it less effective than the high resolution mode and conventional radiographs. All of the composites evaluated showed radiopacity values that fit the ISO 4049 recommendations.

• Journal of Broadcast Engineering
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• v.16 no.3
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• pp.403-415
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• 2011

In this paper, we proposed a hardware architecture to generate digital holograms at high speed. It used the modified computer-generated hologram (CGH) algorithm and adapted the pipeline-based hardware to be able to remove memory bottleneck problem. It uses not the method which generates a hologram by accumulating intermittent holograms but the one which independently generates a pixel of a final hologram and uses the appropriate CGH algorithm for the selected method. Based on the CGH algorithm we proposed the architecture of the digital hologram generator which consists of input interface part, calculating part, and normalizing part. The hardware can decrease memory usage because it repeatedly use object light sources which is stored in the internal buffer. It is also operationally parallelized by vertically adding unit cells. It can generate 86 frames of HD digital hologram per 1 second for 1K light sources.

• Proceedings of the Korea Database Society Conference
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• 1998.09a
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• pp.383-394
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• 1998

This article is an overview of the digital library project, indicating what roles Korea's diverse digital collections may play. Our digital library prototype has simple architecture, consisting of digital repositories, filters, indexing and searching, and clients. Digital repositories include various types of materials and databases. The role of filters is to recognize a format of a document collection and mark the structural components of each of its documents, We are using a database management system (ORACLE and ConText) supporting user-defined functions and access methods that allows us to easily incorporate new object analysis, structuring, and indexing technology into a repository.

• Journal of Conservation Science
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• v.37 no.1
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• pp.25-33
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• 2021

To extend the application of digital technology to the replication of artifacts, meticulous details of the process and the diversity of three-dimensional (3D) printing output materials need to be supplemented. Thus, in this study, a bronze mirror with Hwangbichangcheon inscription was digitalized by 3D scanning, converted into a voxel model, and virtual conservation treatment was performed using a haptic device. Furthermore, the digital mold of the bronze mirror completed by Boolean modeling was printed using a 3D sand-printer. Such contactless replication based on digital technology reflects the stability, precision, expressivity, collectivity, durability, and economic feasibility of artifacts. Its application can be further extended to cultural products as well as such areas as education, exhibition, and research. It is expected to be in high demand for metal artifacts that require casting. If empirical studies through experimental research on casting are supplemented in the future, it could extend the application of digital technology-based contactless replication methods.