• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1876-1885
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• 2003

The artificial potential field (APF) methods provide simple and efficient motion planners for practical purposes. However, these methods have a local minimum problem, which can trap an object before reaching its goal. The local minimum problem is sometimes inevitable when an object moves in unknown environments, because the object cannot predict local minima before it detects obstacles forming the local minima. The avoidance of local minima has been an active research topic in the potential field based path planing. In this study, we propose a new concept using a virtual obstacle to escape local minima that occur in local path planning. A virtual obstacle is located around local minima to repel an object from local minima. We also propose the discrete modeling method for the modeling of arbitrary shaped objects used in this approach. This modeling method is adaptable for real-time path planning because it is reliable and provides lower complexity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1712-1717
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• 2010

To analyze the load of distribution line, real LPs (Load Profile) of AMR (Automatic Meter Reading) customers and VLPs (Virtual Load Profile) of non-AMR customers are required. Accuracy of VLP is an important factor to improve the analysis performance. There are 2 kinds of methods to generate the VLP; one is using ALP (Average Load Profile) per each industrial code and PNN (Probability neural networks) algorithm; the other is using LSI (Load Shape Index) and C5.0 algorithm. In this paper, existing researches are studied, and new method is suggested. Each methods are compared the performance with same LP data of real high voltage customers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.572-574
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• 2014

Researches on three-dimensional multimedia has been performed actively in recent years. Virtual sound technology corresponding to virtual image should be provided to implement 3D multimedia with high quality. Head-related transfer function (HRTF) plays a key role in this research area. HRTFs measured in changing azimuth, elevation, and distance for each and every subject is necessary for ideal solution. However, it is practically impossible to measure all subjects' HRTFs, so various HRTF databases have been built by many researchers. Because HRTF displays quite different aspects from subject to subject, HRTF of dummy head has been used for generic usage. However, mannequin's HRTF showed much worse performance comparing with individual case so this solution should be improved. From previous work, standardization of HRTF based on tensor-singular value decomposition method has been proposed. For effective extraction of standard HRTF, three different decomposition methods are compared in this paper.

• Journal of the Korea Society of Computer and Information
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• v.24 no.9
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• pp.69-75
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• 2019

We propose a method to analyze user requirements to design a virtual reality-based risk management system. This paper presents surveys, interviews, prototype evaluation methods, and implementation process. Architectural heritage is easily exposed to natural and artificial dangers caused by various material combinations and structural features. So, risk management of cultural heritage plays a key role in preserving and managing cultural heritage. However, risk management has been carried out through empirical methods using distributed data. This study analyzes user requirements for designing functions and interfaces of VR-based risk management system and evaluates prototypes to overcome the above problems. As a result, most heritage managers wanted a system function to support risk analysis and response. They also found that they prefer 2D information such as existing drawings and photos rather than 3D information. The results of the user requirements analysis derived from this study will be used to create risk management applications.

• Journal of information and communication convergence engineering
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• v.17 no.3
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• pp.205-212
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• 2019

Motion tracking and localization devices are an important building block of motion tracking systems in a virtual reality (VR) environment. This study is about improving the accuracy of motion and location for enhancing user immersion in experience type VR environment to position tracking technique. In this study, we propose and test a design of such a device. The module data test of the attitude and heading reference system shows that the implementation with the MPU-9250 sensor is successful and adequate to be used with short operation time. We consider various sensor hardware dependencies of VR, and compare various correction methods and filtering methods to lower the motion to photon (MTP) time that user movement is fully reflected on the display using sensor devices. The Kalman filter is used to combine the accelerometer with the gyroscope in the sensing unit.

• Journal of IKEEE
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• v.17 no.2
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• pp.151-158
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• 2013

There are several kind of surface deformation display methods using the fuzzy model. In this paper, we describe three fuzzy display methods for a surface deformation and perform a comparative analysis between the modified fuzzy display method and some conventional fuzzy display methods. In each method, the analysis will be performed through computer simulation in order to show the performance of each algorithm. The results show that the modified method have improved the realism and can be used better than the conventional methods in practical applications.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.12-18
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• 2011

Most smartphone use virtual keypads based on touch-pad. The virtual keypads often make typographical errors because of the physical limitations of device such as small screen and limited input methods. To resolve this problem, many similar word-finding methods have been studied. In the paper, we propose an edit distance method (a well-known string similarity measure) that is modified to consider various types of virtual keypads. The proposed method effectively covers typographical errors in various keypads by converting an input string into a physical key sequence and by reflecting characteristics of virtual keypads to edit scores. In the experiments with various keypads, the proposed method showed better performances than a typical edit distance method.

• Journal of Drive and Control
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• v.10 no.1
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• pp.29-36
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• 2013

Excavation is an important work in mining, earth removal and general earthworks. Nowadays, automation in excavator has been studied by several researchers. In the excavator research methods, simulation is one of the low cost methods for applied to test safely. In this paper, designed a virtual hydraulic excavator that with the control and the dynamic. At first, the simulation of hydraulic system for excavator's attachment such as boom, arm and bucket using Matlab/Simhydraulic is presented. Second, the dynamic model of excavator is distributed to combine with the hydraulic system. For controlling this system, electric joysticks are used to operate the orifice open areas in Main Control Valve. The simulation result is described to analysis the performance of this virtual excavator.

• 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.

• Child Health Nursing Research
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• v.29 no.1
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• pp.24-36
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• 2023

Purpose: This systematic literature review and meta-analysis explored extended reality (XR)-based pediatric nursing simulation programs and analyzed their effectiveness. Methods: A literature search was conducted between May 1 and 30, 2022 in the following electronic databases: MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and CINAHL. The search period was from 2000 to 2022. In total, 6,095 articles were reviewed according to the inclusion and exclusion criteria, and 14 articles were selected for the final content analysis and 10 for the meta-analysis. Data analysis was performed using descriptive statistics and the Comprehensive Meta-Analysis program. Results: XR-based pediatric nursing simulation programs have increased since 2019. Studies using virtual reality with manikins or high-fidelity simulators were the most common, with six studies. The total effect size was statistically significant at 0.84 (95% confidence interval=0.50-1.19, z=4.82, p<.001). Conclusion: Based on the findings, we suggest developing standardized guidelines for the operation of virtual pediatric nursing simulation education and practice. Simultaneously, the application of more sophisticated research designs for effect measurement and the combined applications of various virtual simulation methods are needed to validate the most effective simulation methodology.