• Journal of Internet Computing and Services
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• v.20 no.6
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• pp.55-63
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• 2019

Recently, the use of real-world image data has been increasing to express realistic virtual environments in various application fields such as education, manufacturing, and construction. In particular, with increasing interest in digital twins like smart cities, realistic 3D urban models are being built using real-world images, such as aerial images. However, the captured aerial image includes shadows from the sun, and the 3D city model including the shadows has a problem of distorting and expressing information to the user. Many studies have been conducted to remove the shadow, but it is recognized as a challenging problem that is still difficult to solve. In this paper, we construct a virtual environment dataset including the height map of buildings using 3D spatial information provided by VWorld, and We propose a new shadow detection method using height map and deep learning. According to the experimental results, We can observed that the shadow detection error rate is reduced when using the height map.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.501-506
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• 2006

With the development of Geospatial Technology (GT), many countries and industries have been expanding their investment in constructing a cyber territory. As the critical components of this cyber territory, three-dimensional models and virtual reality contents based on these models of urban areas in particular have been considered. These models and contents can be intensively used for a city to decide the policies efficiently and to attract the interests of peoples while planning and performing large projects. In this study, we have thus constructed the 3D models and virtual reality contents of the large areas along the CheongGye stream to visualize the environment of these areas before and after the CheongGyeCheon restoration project being completed. Furthermore, we propose efficient methods to construct and visualize these large models, such as tile mapping and multiple LOD application.

• The Journal of the Korea Contents Association
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• v.19 no.11
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• pp.499-506
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• 2019

Virtual reality, which is attracting attention due to the 4th Industrial Revolution and commercialization of 5G technology, is expanding its scope from gaming to tourism, leisure, and education, and the VR market is expected to expand continuously. As the VR market scales up in Korea, theme parks combining virtual reality contents are spreading around the city center. Unlike the existing theme parks, VR Theme Park is a small amusement culture space that is organized indoors, and you can enjoy attractions (ride) that can be enjoyed in an amusement park with virtual reality contents. Virtual reality content, which has the same characteristics as a theme park whose purpose is to experience extraordinary experiences, provides high immersion and presence in combination with the physical stimulus of attraction. The virtual reality content combined with the attraction cannot be classified accurately with the existing classification method, so a new classification method is proposed according to the experience type and the installation type. The contents were categorized through the case of the domestic VR theme park, and the planning direction for the creation of the virtual reality attraction contents that was going on was sought.

• Convergence Security Journal
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• v.11 no.4
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• pp.37-42
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• 2011

In this paper, the design methodology of information security is analyzed to implement the ubiquitous city (u-City). The definition, concept, and main u-services of u-City are presented. The main components, functio ns and offering services of u-City management center are presented, and the laws and network security requirements related to protect the personal information in collecting, processing, and exchanging are also analyzed. Three step security levels of Router/Switch, Firewall/VPN, and IPS are applied where main functions of in terception of abnormal packets($1^{st}$ level), access control for each service($2^{nd}$ level), and real-time network monitoring($3^{rd}$ level) are performed. Finally, application cases are presented to validate the security of personal information in providing the u-City services.

• Spatial Information Research
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• v.18 no.5
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• pp.1-11
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• 2010

Since January 2009, Seoul Metro Government(SMG) is operating own Network RTK Systems connecting four(4) GNSS Reference Stations which are installed inside Seoul Metro City area. SMG is currently providing VRS data service via wireless internet for Network-RTK and RINEX data observed from GNSS Reference Stations. This paper will discuss utilization of data available from SMG Network-RTK System for various applications, and present the test results on practicalities of Virtual RINEX data. For the utilization of data available from SMG Network- RTK system, 1)NTRIP data delivery of GNSS realtime observables streaming and converting to RINEX at receiving side, 2) monitoring deformation of bulky structures using GNSS observation were discussed. In addition to those discussion, 3) broadcasting VRS correction data for job site via radio modem after acquiring such correction data on-line using NTRIP based GNSS Internet Radio from SMG Network-RTK System were introduced. For the test results on practicalities of Virtual RINEX data, 1) the post-processing results of the GNSS observation data on a certain point with GNSS Reference Station data have been compared to the post-processing results of Virtual RINEX data on the same point generated from SMG Network-RTK System, and 2) VRS RTK positioning results for a certain point and post-processing results of Virtual RINEX data for the point were compared. The results showed only a few mm difference, and the high possibility for using Virtual RINEX data for post-processing applications.

• Journal of Science Education
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• v.43 no.3
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• pp.271-283
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• 2019

This study examines the effects of virtual reality learning materials on the learners' learning motivation. For this study, we developed a virtual reality learning material for geological learning that allows observation of the characteristics of rocks in Korean topography that is closely related to learning contents. A 15-hour class was conducted with 91 students using virtual reality learning materials developed for first-year science high school students in D city. ARCS learning motivation strategy was used. Pre-test was conducted before the start of the classes and post-test was conducted after the classes. Statistical processing was analyzed using R-3.5.1 version program. As a result, the utilization of virtual reality learning materials has significant effects on attention concentration, satisfaction, and confidence in the learner's motivation factors. Using virtual reality in geological classes, students' interest in learning activities improve their immersion and concentration, which helps them understand the learning contents better.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.5
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• pp.15-25
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• 2000

The purpose of this paper is to examine the visual evaluation structure about the formal changes of streetscape by the different moving speed in two alternative control plans for the building height and the setback regulation. The virtual reality system is applied to the experimental tool. Eighty-two experimental models are made in consideration of the height and the setback of the building regulation cased by Midou-suji street in Osaka City, Japan. and ten typical models are selected by pre-experiment. Since the changes of the landscape structure consists of the height and the setback of the building, four the evaluation items are set: grade of continuity, order, openness, preference. As there are eighty-two landscape models which are too many to be applied in this experiment, ten role models are drawn out and used in this experiment. The mean difference test, discriminant analysis, and multiple linear regression methods had been used for the statistical analysis methods. The results of this study are as follows; 1) It is found out the fact of the difference evaluation structure amount experiments models. 2) From the sketch analysis and interview, it is found out difference cognition structure by the moving speed and alternatives. 3) From the discriminant and regression analysis, it is found out that the evaluation value about continuity becomes low by the moving speed change from walking speed to driving speed. We suggest that continuous experiment should be made with a variety of groups and models, and general and universal results should also be come out of the experiments above.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.497-506
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• 2008

The needs for digital models of real environment such as 3D terrain or cyber city model are increasing. Most of applications related with modeling and simulation require virtual environment constructed from geospatial information of real world in order to guarantee reliability and accuracy of the simulation. The most fundamental data for building virtual environment, terrain elevation and orthogonal imagery is acquired from optical sensor of satellite or airplane. Providing interoperable and reusable digital model is important to promote practical application of high-resolution satellite imagery. This paper presents the new research regarding representation of geospatial information, especially for 3D shape and appearance of virtual terrain. and describe framework for constructing real-time 3D model of large terrain based on high-resolution satellite imagery. It provides infrastructure of 3D simulation with geographical context. Web architecture, XML language and open protocols to build a standard based 3D terrain are presented. Details of standard-based approach for providing infrastructure of real-time 3D simulation using high-resolution satellite imagery are also presented. This work would facilitate interchange and interoperability across diverse systems and be usable by governments, industry scientists and general public.

• Journal of Korean Academy of Nursing
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• v.51 no.4
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• pp.465-477
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• 2021

Purpose: This study aimed to evaluate the effects of head monted display based home-visits virtual reality simulation (HVRS) program developed for undergraduate nursing students. Methods: A nonequivalent control group with a non-synchronized design was utilized and 84 participants (experimental group, 44; control group, 40) were recruited from August 31, 2020 to November 8, 2020 in Gwangju metropolitan city. The HVRS program consisted of scenarios of three nursing cases, hypertension, diabetes mellitus, and stroke. Data were analyzed SPSS version 25.0 for Windows. Results: At the completion of HVRS, significant differences were found between groups in knowledge of home-visits (t = 4.73, p < .001), self-confidence (t = 6.63, p < .001), self-efficacy (t = 3.13, p = .002), and clinical competency (t = 4.13, p < .001). No significant difference was shown between groups in nursing knowledge about strokes, a subcategory of knowledge pertaining to home visits. Conclusion: The HVRS program developed for undergraduate nursing students is effective in improving knowledge of home-visits, self-confidence, self-efficacy, and clinical competency for nursing students.

• Journal of Power Electronics
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• v.12 no.4
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• pp.548-558
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• 2012

In this paper, a novel offset-based single-state pulse width modulation (PWM) method for achieving zero common-mode voltage (CMV) and reducing switching losses in multilevel inverters is presented. The specific active switching state of the zero common-mode (ZCM) voltage that approximates the reference voltage can be deduced from the switching state sequence of the reduced CMV phase disposition PWM (CMV PD PWM) method. From the reference leg voltages for the zero common-mode voltage, an N-to-2-level transformation defines a virtual two-level inverter and the corresponding nominal leg voltage references. The commutation process of the reduced CMV PD PWM method in a multilevel inverter and its outputs can be simply followed in a nominal switching time diagram for the virtual inverter. The characteristics of the reduced CMV PD PWM and the single-state PWM for zero common-mode voltage are analyzed in detail in this paper. The theoretical analysis of the proposed PWM method is verified by experimental results.