• International Journal of Fluid Machinery and Systems
• /
• v.10 no.3
• /
• pp.287-295
• /
• 2017

The most detrimental pressure pulsations in high-head pump-turbines is caused by the rotor-stator interaction (RSI) between the guide vanes and runner blades. When the pump-turbine operates in the S-shaped region of the characteristic curves, the deteriorative flow structures may significantly strengthen RSI, causing larger pressure pulsations and stronger vibration with an increased risk of mechanical failure. CFD simulations were carried out to analyze the impacts of flow evolution on the pressure pulsations in the S-shaped region of a model pump-turbine. The results show that the reverse flow vortex structures (RFVS) at the runner inlet have regular development and transition patterns when discharge reduces from the best efficiency point (BEP). The RFVS first occur at the hub side, and then shift to the mid-span near the no-load point, which cause the strongest pressure pulsations. The locally distributed RFVS at hub side enhance the local RSI and makes the pressure fluctuations at the corresponding sections stronger than those at the rest sections along the spanwise direction. Under the condition of RFVS at the mid-span, the smaller flow rate make the smaller difference of pressure pulsation amplitudes in the spanwise direction. Moreover, the rotating stall, rotating at 35.7%-62.5% of the runner rotational frequency, make the low frequency components of pressure pulsations distribute unevenly along the circumference in the vaneless space. However, it have little influence on the distributions of high components.

• Journal of the Korea Convergence Society
• /
• v.13 no.2
• /
• pp.143-150
• /
• 2022

Audio-based SNS also needs a visual guide to reach the contents desired by the users. Therefore, this study investigates visual interface design elements that influence the experience of using audio contents in audio-based SNS. Prior researches have identified that the generally acknowledged interface design elements are important for the usability of audio contents. Through the analysis of the currently launched audio-based SNS, the influence of general interface elements were again confirmed, and via the analysis of other audio content services, a new interface evaluation element was explored. Accordingly, with five general interface evaluation elements-layout, color, icon, typography, graphic image, multimedia elements are newly defined and proposed as crucial factors in evaluating the UI of audio-based SNS.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.05a
• /
• pp.569-570
• /
• 2022

Failure situations occur frequently in the industry, and the existing 2D-based manual for this purpose is not intuitive to understand and it is difficult to immediately interact with maintenance experts. In this paper, we propose a technology that enables workers to perform maintenance in real time with the help of experts without restrictions in time and place based on augmented reality when a failure situation occurs at a remote location. A local virtual human-based expert diagnoses a failure situation based on an adapted panoramic image of a remote failure situation while wearing an HMD headset, and gives instructions to a remote operator. In addition, in an augmented reality (AR) environment in a remote location, for the interaction between the operator and the expert, the HMD's microphone is used to create the expert's hand as well as verbal communication. You can use to point or draw a picture. If this technology is used, it is possible to overcome the limitations of the existing 2D-based manual, and to provide assistance in performing maintenance smoothly remotely even if an expert does not directly visit a remote location.

• Geomechanics and Engineering
• /
• v.38 no.3
• /
• pp.319-334
• /
• 2024

The current theories on the interaction between surrounding rock and support in deep-buried tunnels do not consider the form of pre-reinforcement support or the flexibility of primary support, leading to a discrepancy between theoretical solutions and practical applications. To address this gap, a comprehensive mechanical model of the tunnel with pre-reinforced rock was established in this study. The equations for internal stress, displacement, and the radius of the plastic zone in the surrounding rock were derived. By understanding the interaction mechanism between flexible support and surrounding rock, the three-dimensional construction analysis solution of the tunnel could be corrected. The validity of the proposed model was verified through numerical simulations. The results indicate that the reduction of pre-deformation significantly influences the final support pressure. The pre-reinforcement support zone primarily inhibits pre-deformation, thereby reducing the support pressure. The support pressure mainly affects the accelerated and uniform movement stage of the surrounding rock. The generation of support pressure is linked to the deformation of the surrounding rock during the accelerated movement stage. Furthermore, the strength of the pre-reinforcement zone of the surrounding rock and the strength of the shotcrete have opposite effects on the support pressure. The parameters of the pre-reinforcement zones and support materials can be optimized to achieve a balance between surrounding rock deformation, support pressure, cost, and safety. Overall, this study provides valuable insights for predicting the deformation of surrounding rock and support pressure during the dynamic construction of deep-buried weak rock tunnels. These findings can guide engineers in improving the construction process, ensuring better safety and cost-effectiveness.

• Journal of Digital Convergence
• /
• v.12 no.8
• /
• pp.211-217
• /
• 2014

In this paper, by using geofencing technology to set the area you want to move tourists. Geofence set of tourists in the region enters the smartphone by sending e-mail or SMS alarm to display a detailed map of the area to visit assistance. When you arrive at the destination of the museum exhibits or exhibits to the NFC tag attached to each corresponding to a web server for a detailed description of the exhibits from the get-down. Multimedia content using an existing exhibits described. Media of exhibition space and the interaction between the visitors tour guide system capable was built.

• Electronics and Telecommunications Trends
• /
• v.35 no.1
• /
• pp.60-70
• /
• 2020

Artificial intelligence (AI) is expected to bring about a wide range of changes in the industry, based on the assessment that it is the most innovative technology in the last three decades. The manufacturing field is an area in which various artificial intelligence technologies are being applied, and through accumulated data analysis, an optimal operation method can be presented to improve the productivity of manufacturing processes. In addition, AI technologies are being used throughout all areas of manufacturing, including product design, engineering, improvement of working environments, detection of anomalies in facilities, and quality control. This makes it possible to easily design and engineer products with a fast pace and provides an efficient working and training environment for workers. Also, abnormal situations related to quality deterioration can be identified, and autonomous operation of facilities without human intervention is made possible. In this paper, AI technologies used in smart factories, such as the trends in generative product design, smart workbench and real-sense interaction guide technology for work and training, anomaly detection technology for quality control, and intelligent manufacturing facility technology for autonomous production, are analyzed.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2676-2681
• /
• 2003

The Haptic Exploration Laboratory at The Johns Hopkins University is currently exploring many problems related to haptics (force and tactile information) in human-machine systems. We divide our work into two main areas: virtual environments and robot-assisted manipulation systems. Our interest in virtual environments focuses on reality-based modeling, in which measurements of the static and dynamic properties of actual objects are taken in order to produce realistic virtual environments. Thus, we must develop methods for acquiring data from real objects and populating pre-defined models. We also seek to create systems that can provide active manipulation assistance to the operator through haptic, visual, and audio cues. These systems may be teleoperated systems, which allow human users to operate in environments that would normally be inaccessible due to hazards, distance, or scale. Alternatively, cooperative manipulation systems allow a user and a robot to share a tool, allowing the user to guide or override the robot directly if necessary. Haptics in human-machine systems can have many applications, such as undersea and space operations, training for pilots and surgeons, and manufacturing. We focus much of our work on medical applications.

• The Journal of Korean Association of Computer Education
• /
• v.6 no.3
• /
• pp.99-108
• /
• 2003

This paper indicates limitations of the existing VOD(Video on Demand)-based on-line education systems and presents the design and implementation of Education on Demand (EOD) system as an alternative. EOD system is based on meta information expressed in XML and component technology. Overall system consists of authoring tool. contents server, learning policy system and contents viewer. which are utilized throughout the learning contents life-cycle. EOD system enables automated contents management using meta information exchange methodology that is conformant to the SCORM meta data presentation scheme. In addition, integrated management of interaction and feedback information along with the learning policy system provides customized learning guide for each individual learner. With the development of EOD system, this paper discusses about advanced on-line education system which surpasses existing content-providing-only systems.

• Journal of Digital Contents Society
• /
• v.17 no.6
• /
• pp.545-553
• /
• 2016

In this study, we propose an information providing and learning system using augmented reality in the exhibition (museum, performance) environment. In a typical exhibition space, a description of a picture or a photograph is provided in a printed matter or a space in the form of an information space (explanatory space), or an auxiliary explanation using an 'audio guide' or a 'docent' program. Augmented reality technology is applied to the exhibition space in the form of a fusion of these methods, and the description of the exhibition is provided to the user in various forms such as text, picture, audio and image, thereby providing stereoscopic information and learning. We apply the augmented reality technology in a specific exhibition space and utilize it as a tool of providing information and learning using image description of pictures.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.10 no.2
• /
• pp.213-227
• /
• 2014

The Purpose of this research was to examine the influence of university students' self-leadership and career decision self-efficacy upon career preparation behavior. A total of 342 participants in 1th ~ 3th grades from universities in Seoul. Result from multiple regression analysis indicated the following. First, self-leadership and career decision self-efficacy had an impact on career preparation behavior. Second self-leadership had impact an career decision self-efficacy. Third, career decision self-efficacy had an impact on career preparation behavior. The result showed that there was significant interaction. Finally, the limitations of this study and suggestions for future research on career path preparation behavior were discussed. The implication of this study is that self-leadership and self-efficacy can the university students' career path preparation behavior. This research findings, theoretical and practical implications were suggested. Consequently it mean that the career guide program for university student. Therefore, effective counseling strategies to enhance career preparation behavior.