• Title/Summary/Keyword: Digital techniques

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A Study on Efficient Technique of 3-D Terrain Modelling (3차원 지형모델링의 효율적 기법에 관한 연구)

  • 윤철규;신봉호;양승룡;엄재구
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.15 no.2
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    • pp.207-213
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    • 1997
  • The purpose of this study is to aim at presenting efficient technique of 3-D Terrain Modelling through multilateral approach methods and to compare with raw data, using low-densed randomly located point data. The subject religion of this study are selected two sites and take into consideration for degree of freedom about low-densed randomly located point data. The result of this study by precision analysis of digital cartographic map-ping using low-densed randomly located point data bave shown that . First, making digital cartographic map, the technique of making it using low-desned randomly located point data by TIN-based results to good and fast run-time in A and B sites all together. Second, the visualization analysis results of digital cartographic map using TIN and GRID-based terrain modeling techniqus similar exacts A and B sites, but the terrain modeling techniqus by TIN-based are small data size than GRID-based with the data with the data size of saving with DXF files. Third, making digital catographic map using terrain modeling techniques by Grid-based, the standard errors of low-densed randomly located point data and interpolated data using gridding method have more good results by radial basis function interpolation techniques at A and B sites all together.

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Design and Implementation of eRTOS Real-time Operating Systems for Wearable Computers (웨어러블 컴퓨터를 위한 저전력 실시간 운영체제 eRTOS 설계 및 구현)

  • Cho, Moon-Haeng;Choi, Chan-Woo;Lee, Cheol-Hoon
    • The Journal of the Korea Contents Association
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    • v.8 no.9
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    • pp.42-54
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    • 2008
  • In recent years, embedded systems have been expanding their application domains from traditional embedded systems such as military weapons, robots, satellites and digital convergence systems such as celluar phones, PMP(Portable Multimedia Player), PDAs(Personal Digital Assistants) to Next Generation Personal Computers(NGPCs) such as eating PCs, wearable computers. The NGPCs are network-based, human-centric digital information devices diverged from the traditional PCs used mainly for document writing, internet searching and database management. Wearable computers with battery capacity and memory size limitations have to use real-time operating systems with small footprints and low power management techniques to provide user's QoS in spite of hardware constraints. In this paper, we have designed and implemented a low-power RTOS (called eRTOS) for wearable computers. The implemented eRTOS has 18KB footprints and the dynamic power management and the device power management schemes are adapted in it. Experimental results with wearable computer applications show that the low power techniques could save energy up to 47 %.

Digital Video Scrambling Methods using Motion Vector and Intra Prediction Mode (움직임 벡터와 인트라 예측 모드를 이용한 디지털 비디오 스크램블링 방법)

  • Ahn, Jin-Haeng;Jeon, Byeung-Woo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.42 no.4 s.304
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    • pp.133-142
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    • 2005
  • In this paper, two digital video scrambling methods are proposed as simple means of the digital content protection techniques. One is inter block scrambling using motion vector, the other is intra block scrambling using intra prediction mode. The proposed inter block scrambling method distorts the original sequences by swapping horizontal and vertical components of motion vector. This method can be applied on most common video coding techniques such as MPEG-1, 2, 4, H.264, etc. The proposed intra block scrambling method distorts the original sequences by modifying intra prediction mode that is property of H.254 video coding technique. Both methods do not cause my bit rate increase after scrambling. Moreover, they have low complexity because they need only simple operation like XOR. Especially, the proposed intra block scrambling does not distort inter blocks directly. But inter blocks are distorted by error propagation effect as much as intra blocks. This paper introduces two new digital video scrambling method and verifies its effectiveness through simulation.

Comparison of intraoral scanning and conventional impression techniques using 3-dimensional superimposition

  • Rhee, Ye-Kyu;Huh, Yoon-Hyuk;Cho, Lee-Ra;Park, Chan-Jin
    • The Journal of Advanced Prosthodontics
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    • v.7 no.6
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    • pp.460-467
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    • 2015
  • PURPOSE. The aim of this study is to evaluate the appropriate impression technique by analyzing the superimposition of 3D digital model for evaluating accuracy of conventional impression technique and digital impression. MATERIALS AND METHODS. Twenty-four patients who had no periodontitis or temporomandibular joint disease were selected for analysis. As a reference model, digital impressions with a digital impression system were performed. As a test models, for conventional impression dual-arch and full-arch, impression techniques utilizing addition type polyvinylsiloxane for fabrication of cast were applied. 3D laser scanner is used for scanning the cast. Each 3 pairs for 25 STL datasets were imported into the inspection software. The three-dimensional differences were illustrated in a color-coded map. For three-dimensional quantitative analysis, 4 specified contact locations(buccal and lingual cusps of second premolar and molar) were established. For two-dimensional quantitative analysis, the sectioning from buccal cusp to lingual cusp of second premolar and molar were acquired depending on the tooth axis. RESULTS. In color-coded map, the biggest difference between intraoral scanning and dual-arch impression was seen (P<.05). In three-dimensional analysis, the biggest difference was seen between intraoral scanning and dual-arch impression and the smallest difference was seen between dual-arch and full-arch impression. CONCLUSION. The two- and three-dimensional deviations between intraoral scanner and dual-arch impression was bigger than full-arch and dual-arch impression (P<.05). The second premolar showed significantly bigger three-dimensional deviations than the second molar in the three-dimensional deviations (P>.05).

Convergence and integration study related to development of digital contents for radiography training using dental radiograph and augmented reality (치과방사선사진과 증강현실을 활용한 방사선촬영법 숙련용 디지털 콘텐츠 개발에 대한 융복합 연구)

  • Gu, Ja-Young;Lee, Jae-Gi
    • Journal of Digital Convergence
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    • v.16 no.12
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    • pp.441-447
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    • 2018
  • This study aims to develop digital techniques that enable repeated practice of dental radiography using augmented reality technology. A three-dimensional object was fabricated by superimposing a photograph of an adult model and a computed tomography image of a manikin phantom. The system was structured using 106 radiographs such that one of these saved radiographs is opened when the user attempts to take a radiograph on a mobile device. This system enabled users to repeatedly practice at the pre-clinical stage without exposure to radiation. We attempt to contribute to enhancing dental hygienists' competency in dental radiography using these techniques. However, a system that enables the user to actually take a radiograph based on face recognition would be more useful in terms of practice, so additional studies are needed on the topic.

A Study on VR Game Production Techniques to Improvement of Visual Immersion (시각적 몰입감 향상을 위한 VR 게임 제작 기법 연구)

  • Lee, Lang-Goo;Chung, Jean-Hun
    • Journal of Digital Convergence
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    • v.19 no.11
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    • pp.457-462
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    • 2021
  • This study is about production techniques that can improve visual immersion in VR games. First, we reviewed the theory of VR games, current status, visual and immersion through prior work, and selected samples to extract key components that can improve visual immersion in VR games. and, VR games were produced and developed by applying the concept of COVID-19, which is currently popular around the world. As a result, the resolution of technical Element's, frame rate, viewing angle, brightness of lighting, design quality, and Contextual Element's storytelling, background, directing, color, texture, interest and fun because is Significant results that can induce and improve immersion were obtained, and in the end, smooth gameplay was realized. Through this research process and results, it is expected that it will be a basic data in the field of production and development of VR games that can induce and improve users' visual immersion in the future.

Application of Digital Signal Analysis Technique to Enhance the Quality of Tracer Gas Measurements in IAQ Model Tests

  • Lee, Hee-Kwan;Awbi, Hazim B.
    • Journal of Korean Society for Atmospheric Environment
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    • v.23 no.E2
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    • pp.66-73
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    • 2007
  • The introduction of tracer gas techniques to ventilation studies in indoor environments provides valuable information that used to be unattainable from conventional testing environments. Data acquisition systems (DASs) containing analogue-to-digital (A/D) converters are usually used to function the key role that records signals to storage in digital format. In the testing process, there exist a number of components in the measuring equipment which may produce system-based inference to the monitored results. These unwanted fluctuations may cause significant error in data analysis, especially when non-linear algorithms are involved. In this study, a pre-processor is developed and applied to separate the unwanted fluctuations (noise or interference) in raw measurements and to reduce the uncertainty in the measurement. Moving average, notch filter, FIR (Finite Impulse Response) filters, and IIR (Infinite Impulse Response) filters are designed and applied to collect the desired information from the raw measurements. Tracer gas concentrations are monitored during leakage and ventilation tests in the model test room. The signal analysis functions are introduced to carry out the digital signal processing (DSP) work. Overall the FIR filters process the $CO_2$ measurement properly for ventilation rate and mean age of air calculations. It is found that, the Kaiser filter was the most applicable digital filter for pre-processing the tracer gas measurements. Although the IIR filters help to reduce the random noise in the data, they cause considerable changes to the filtered data, which is not desirable.

An Improved Joint Detection of Frame, Integer Frequency Offset, and Spectral Inversion for Digital Radio Mondiale Plus

  • Kim, Seong-Jun;Park, Kyung-Won;Lee, Kyung-Taek;Choi, Hyung-Jin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.2
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    • pp.601-617
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    • 2014
  • In digital radio broadcasting systems, long delays are incurred in service start time when tuning to a particular frequency because several synchronization steps, such as symbol timing synchronization, frame synchronization, and carrier frequency offset and sampling frequency offset compensation are necessary. Therefore, the operation of the synchronization blocks causes delays ranging from several hundred milliseconds to a few seconds until the start of the radio service after frequency tuning. Furthermore, if spectrum inversed signals are transmitted in digital radio broadcasting systems, the receivers are unable to decode them, even though most receivers can demodulate the spectral inversed signals in analog radio broadcasting systems. Accordingly, fast synchronization techniques and a method for spectral inversion detection are required in digital radio broadcasting systems that are to replace the analog radio systems. This paper presents a joint detection method of frame, integer carrier frequency offset, and spectrum inversion for DRM Plus digital broadcasting systems. The proposed scheme can detect the frame and determine whether the signal is normal or spectral inversed without any carrier frequency offset and sampling frequency offset compensation, enabling fast frame synchronization. The proposed method shows outstanding performance in environments where symbol timing offsets and sampling frequency offsets exist.

Broken Integrity Detection of Video Files in Video Event Data Recorders

  • Lee, Choongin;Lee, Jehyun;Pyo, Youngbin;Lee, Heejo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.8
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    • pp.3943-3957
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    • 2016
  • As digital evidence has a highly influential role in proving the innocence of suspects, methods for integrity verification of such digital evidence have become essential in the digital forensic field. Most surveillance camera systems are not equipped with proper built-in integrity protection functions. Because digital forgery techniques are becoming increasingly sophisticated, manually determining whether digital content has been falsified is becoming extremely difficult for investigators. Hence, systematic approaches to forensic integrity verification are essential for ascertaining truth or falsehood. We propose an integrity determination method that utilizes the structure of the video content in a Video Event Data Recorder (VEDR). The proposed method identifies the difference in frame index fields between a forged file and an original file. Experiments conducted using real VEDRs in the market and video files forged by a video editing tool demonstrate that the proposed integrity verification scheme can detect broken integrity in video content.

Digital Audio Watermarking for Copyright Protection of Broadcasting Content (방송 컨텐츠 보호를 위한 디지털 오디오 워터마킹)

  • 오현오;윤대희;석종원;홍진우
    • Journal of Broadcast Engineering
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    • v.6 no.1
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    • pp.3-12
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    • 2001
  • Over the last few years, digital audio watermarking has become an interesting issue In many application areas, including digital broadcasting. This is primarily motivated by a need to provide copyright protection of digital audio content. Digital watermarking is a technique to embed copyright or other information int? the underlying data. Several possible audio watermarking techniques have been developed including spread spectrum watermarking, echo watermarking, phase coding, and patchwork. In this paper, we describe some requirements of digital audio watermarking as a tool for copyright protection of broadcasting content, and compare popular audio watermarking algorithms in some significant aspects.

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