• Title/Summary/Keyword: Virtual presence

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Evaluation of the WKB method and the MWKB method in the analysis of planar waveguides (평면도 도파로해석에 있어서 WKB방법 및 MWKB방법의 평가)

  • Chung, Min-Sub;Kim, Chang-Min
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.1
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    • pp.146-158
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    • 1996
  • The WKB method has been widely used in evaluating of the propagation characteristics of planar waveguides with graded-index profiles. This method, however, yields large errors when a turning point is near or at the discontinuity in the presence of the index discontinuity or index slope discontinuity. Especially, in the case of a truncated-index profile, this phenomenon appears more clearly in the low-order modes and near the cutoff regions. The MWKB method is introduced to reduce these inherent errors of the conventional WKB method. The MWKB method is based on both the linearization of the index profile from an index discontinuity and the introduction of a virtual turning point. It is noticed that the b-v curves obtained by the MWKB method agree well with those of the finite-difference method, and that the phase shift at a turning point depends on both the index profile and its propagation constant. (author). refs., figs.

3D City Modeling Using Laser Scan Data

  • Kim, Dong-Suk;Lee, Kwae-Hi
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.505-507
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    • 2003
  • This paper describes techniques for the automated creation of geometric 3D models of the urban area us ing two 2D laser scanners and aerial images. One of the laser scanners scans an environment horizontally and the other scans vertically. Horizontal scanner is used for position estimation and vertical scanner is used for building 3D model. Aerial image is used for registration with scan data. Those models can be used for virtual reality, tele-presence, digital cinematography, and urban planning applications. Results are shown with 3D point cloud in urban area.

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Intelligent Technique Application for Autonomous Lateral Position Control of an Unmanned 4 Wheel Steered Snowplow Robotic Vehicle

  • Jung, Seul;Hsia, T.C.
    • IEMEK Journal of Embedded Systems and Applications
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    • v.6 no.3
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    • pp.132-138
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    • 2011
  • This paper presents an intelligent control approach for lateral position control of an autonomous four wheel steered snowplowing robotic vehicle. The vehicle is built for removing snow on the highway. Dynamics of the vehicle is derived and linearized for LQR control. Lateral position is controlled by the LQR method first, then the neural network control technique is introduced to improve tracking performances under the presence of load. The feasibility of using four wheel steering control is investigated by simulation studies of lateral position tracking of the Ford F-250 truck model. Performances of a LQR control method and a neural network control method under virtual snowplowing situation are compared.

Double-Objective Finite Control Set Model-Free Predictive Control with DSVM for PMSM Drives

  • Zhao, Beishi;Li, Hongmei;Mao, Jingkui
    • Journal of Power Electronics
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    • v.19 no.1
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    • pp.168-178
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    • 2019
  • Discrete space vector modulation (DSVM) is an effective method to improve the steady-state performance of the finite control set predictive control for permanent magnet synchronous motor drive systems. However, it requires complex computations due to the presence of numerous virtual voltage vectors. This paper proposes an improved finite control set model-free predictive control using DSVM to reduce the computational burden. First, model-free deadbeat current control is used to generate the reference voltage vector. Then, based on the principle that the voltage vector closest to the reference voltage vector minimizes the cost function, the optimal voltage vector is obtained in an effective way which avoids evaluation of the cost function. Additionally, in order to implement double-objective control, a two-level decisional cost function is designed to sequentially reduce the stator currents tracking error and the inverter switching frequency. The effectiveness of the proposed control is validated based on experimental tests.

Recent advances in surveillance colonoscopy for dysplasia in inflammatory bowel disease

  • Soo-Young Na;Won Moon
    • Clinical Endoscopy
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    • v.55 no.6
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    • pp.726-735
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    • 2022
  • Inflammatory bowel disease (IBD) has a global presence with rapidly increasing incidence and prevalence. Patients with IBD including those with ulcerative colitis and Crohn's disease have a higher risk of developing colorectal cancer (CRC) compared to the general population. Risk factors for CRC in patients with IBD include long disease duration, extensive colitis, primary sclerosing cholangitis, family history of CRC, stricture, and prior dysplasia. Surveillance colonoscopy for CRC in patients with IBD should be tailored to individualized risk factors and requires careful monitoring every year to every five years. The current surveillance techniques are based on several guidelines. Chromoendoscopy with targeted biopsy is being recommended increasingly, and high-definition colonoscopy is gradually replacing standard-definition colonoscopy. However, it remains unclear whether chromoendoscopy, virtual chromoendoscopy, or white-light endoscopy has better efficiency when a high-definition scope is used. With the development of new endoscopic instruments and techniques, the paradigm of surveillance strategy has gradually changed. In this review, we discuss cutting-edge surveillance colonoscopy in patients with IBD including a review of literature.

A Study on effective directive technique of 3D animation in Virtual Reality -Focus on Interactive short using 3D Animation making of Unreal Engine- (가상현실에서 효과적인 3차원 영상 연출을 위한 연구 -언리얼 엔진의 영상 제작을 이용한 인터렉티브 쇼트 중심으로-)

  • Lee, Jun-soo
    • Cartoon and Animation Studies
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    • s.47
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    • pp.1-29
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    • 2017
  • 360-degree virtual reality has been a technology that has been available for a long time and has been actively promoted worldwide in recent years due to development of devices such as HMD (Head Mounted Display) and development of hardware for controlling and executing images of virtual reality. The production of the 360 degree VR requires a different mode of production than the traditional video production, and the matters to be considered for the user have begun to appear. Since the virtual reality image is aimed at a platform that requires enthusiasm, presence and interaction, it is necessary to have a suitable cinematography. In VR, users can freely enjoy the world created by the director and have the advantage of being able to concentrate on his interests during playing the image. However, the director had to develope and install the device what the observer could concentrate on the narrative progression and images to be delivered. Among the various methods of transmitting images, the director can use the composition of the short. In this paper, we will study how to effectively apply the technique of directing through the composition of this shot to 360 degrees virtual reality. Currently, there are no killer contents that are still dominant in the world, including inside and outside the country. In this situation, the potential of virtual reality is recognized and various images are produced. So the way of production follows the traditional image production method, and the shot composition is the same. However, in the 360 degree virtual reality, the use of the long take or blocking technique of the conventional third person view point is used as the main production configuration, and the limit of the short configuration is felt. In addition, while the viewer can interactively view the 360-degree screen using the HMD tracking, the configuration of the shot and the connection of the shot are absolutely dependent on the director like the existing cinematography. In this study, I tried to study whether the viewer can freely change the cinematography such as the composition of the shot at a user's desired time using the feature of interaction of the VR image. To do this, 3D animation was created using a game tool called Unreal Engine to construct an interactive image. Using visual scripting of Unreal Engine called blueprint, we create a device that distinguishes the true and false condition of a condition with a trigger node, which makes a variety of shorts. Through this, various direction techniques are developed and related research is expected, and it is expected to help the development of 360 degree VR image.

Factors Affecting Users to Adopt Voice Shopping: Empirical evidence from the UTAUT model (인공지능 기반 음성쇼핑(Voice Shopping)의 수용의도에 영향을 미치는 요인 연구: 확장된 통합기술수용모델을 중심으로)

  • Ahn, Suho;Jo, Woong;Chung, Doohee
    • Journal of Technology Innovation
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    • v.27 no.4
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    • pp.111-144
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    • 2019
  • As virtual assistants rapidly diffused into the market, the voice shopping market is expected to expand. The purpose of this study is to identify the factors that determine the consumers' intention to adopt voice shopping by using the unified theory of acceptance and use of technology(UTAUT). In this study, we set variables that influence the intention to adoption of voice shopping with performance expectation and effort expectations as the variables of UTAUT and playfulness expectations as an extended variable. In addition, we also include four voice secretary attributes such as response accuracy, compatibility, social presence, and safety in our research model to investigate the source of motivation of voice shopping adoption. The result of this analysis shows that variables such as performance expectation, effort expectation, and amusement expectation have a positive effect on the intention to adoption of voice shopping. With respect to the four voice shopping attributes, compatibility had a positive effect on performance expectancy, effort expectancy, and playfulness expectancy. Social presence has a positive effect on playfulness expectancy. Safety has a positive effect on effort expectancy and playfulness expectancy. On the other hand, response accuracy is not significant for performance expectancy, effort expectancy, and playfulness expectancy. This study reveals the determinants of intention to adopt the new purchasing method called voice shopping, and suggests the important factors for the innovation of commerce business.

The Effects of VR-based Cultural Heritage Experience on Visit Intention (VR 기반 문화유산 체험이 방문의도에 미치는 영향)

  • Yoo, Kun Woo;Hwang, Kyunghwa;Kwon, Ohbyung
    • The Journal of Society for e-Business Studies
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    • v.26 no.2
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    • pp.95-122
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    • 2021
  • As it recently became a non-face-to-face society because of the COVID-19 Pandemics, attempts have been made to experience heritage based on virtual reality (VR). Despite the satisfaction of VR contents, however, questions are being raised about whether the VR experience leads to visit a heritage tour or reduces to visit a heritage tour. This study examined how VR-based heritage experiences affect the visit intention of heritage sites. In addition, this study investigated how VR-based experiences differently affect the visit intention compared to web-based experiences. To this end, based on the information success model proposed by DeLone and McLean, this study examined how the perception for system quality and information quality through VR (vs. web) experience affects the intention of visiting the historical site. The results demonstrated that satisfaction was positively influenced by the convenience of system quality and the presence and usefulness of information quality and that the presence and satisfaction positively affected continuance intention. In addition, continuous intention to use positively affected the visit intention of heritage sites. Lastly, it has been shown that the usefulness of information quality in groups experiencing content through the Web (vs. VR) has a greater impact on the intent of continuous use. Based on the results of this study, we discussed ways to organize tourism content to increase the intention of visiting heritage sites.

Analysis of the Playful Characteristic of Virtual Reality(VR) Games - Focusing on Huizinga and Caillois's Play Theory (VR(Virtual Reality) 게임의 놀이적 특성 분석 - 하위징아와 카이저의 놀이 이론을 중심으로)

  • Park, Man Su;Jin, Qian Xiong;Han, Dong Sub
    • The Journal of the Korea Contents Association
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    • v.18 no.8
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    • pp.148-156
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    • 2018
  • This study focuses on the play aspect of the existing digital games and VR games as part of a basic research for facilitating discussion on VR games. As a method for this research, the play aspect of digital games was classified based on the play theory by Johan Huizinga and Roger Caillois, followed by examination on the play characteristics of VR games according to the established classification. As a result, VR games share a significant portion of play characteristics with digital games. Nevertheless, in VR games the player is allowed unimpeded physical activity while having the HMD on and complete disconnection from the real world via new input/output devices. In the end, the transformation of play environment results in various sensory stimulation, and in turn influences the player's experiences in areas such as presence, immersion, emotional enjoyment and satisfaction. This study is expected to serve as an important indicator for studies on the characteristics of VR contents which is certain to develop in a wide range of directions in the future.

Three-dimensional analysis of the cusp variation patterns of mandibular second premolar in Koreans (일부 한국인 하악 제2소구치 교두 변이 양상에 대한 3차원적 분석)

  • Nam, Shin-Eun
    • Journal of Technologic Dentistry
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    • v.42 no.3
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    • pp.220-227
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    • 2020
  • Purpose: This study aims to investigate the cusp variation pattern of the Korean mandibular second premolar and to determine the difference in tooth diameter and surface area using a virtual three-dimensional model. Methods: Dental casts from 69 students were scanned as a virtual dental models with a three-dimensional dental model scanner. Tooth diameter, absolute and relative individual areas, total crown area, the number of lingual cusps and central groove pattern were analyzed using RapidForm 2004. The Mann-Whitney U-test and the Kruskal-Wallis test were performed to verify sexual dimorphism, the difference in tooth diameter and surface according to the cusp variation pattern (α=0.05). Results: There was no significant difference except in buccolingual diameter (p<0.05) and buccolingual diameter at the cervix (p<0.05). The relative surface area of the total clinical crown was 65.76% for the buccal half and 34.24% for the lingual half, with a ratio of 2:1. In the case of the presence of two lingual cusps, the ratio was 21.47% for the mesiolingual half and 14.12% for the distaolingual half, with a ratio of 3:2. The dominant central groove patterns of the second premolar were the H-pattern (42.0%), followed by the Y-pattern (37.7%), then the U-pattern (20.3%). The relative buccal half was largest in the U-pattern central groove and the relative lingual half was largest in the Y-pattern central groove (p<0.05). Conclusion: This study is significant in that it measured quantitative surface areas and the findings could be a meaningful reference to comprehend dental anatomy in Koreans.