• Transactions of Materials Processing
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• v.32 no.3
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• pp.122-128
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• 2023

As electric vehicles (EV) have increasingly replaced the conventional vehicles with internal combustion engines (ICE), most of automotive makers are actively devoting to the technology development of EV parts. Accordingly, the manufacturing process for power source has been also shifting from engine/transmission to EV motor/reducer system. However, lack of experience in developing the EV motor still remains as a technical challenge. In this paper, we employed the forming simulation based on finite element modeling to solve this problem. In particular, in order to increase the accuracy of the forming simulation, we introduced the elastic-plastic constitutive model parameters for polymer-copper hybrid wire by investigating the individual strain-stress curves, and elastic modulus of polymer and copper. Then, the reliability of modeling procedure was confirmed by comparing the simulated results with experiments. Finally, the identified mechanical properties and finite element modeling were applied to a hairpin forming process, which involves multiple deformation paths such as bending, pressing, widening, and twisting. The proposed numerical approach can replace common experience or experiment based trials by reducing production time and cost in the future.

• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.2
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• pp.197-204
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• 2023

The importance of each warfighting function for Army TIGER unit attack drones is measured using the AHP technique. As a result, the importance of attack drones is high in the order of maneuver, firepower, intelligence, command/control, protection, and operation sustainment, but the importance of maneuver, firepower, and intelligence are almost similar. In addition, it is analyzed that attack drones capable of carrying out day and night missions by being equipped with an EO/IR sensor and being commanded/controlled in conjunction with the C4I system to eliminate threats with small bombs or aircraft collisions is needed. Finally, based on the results of this study, a virtual battle scenario for attack drones is proposed.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1103-1106
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• 2008

Data Grid is a kind of Grid computing provides the cooperative environment through the distributed data sharing, and can manage the massive data easily and efficiently. We designed and implemented Globus Toolkit4 (GT4) based database access and integration service (GDAIS). This service was implemented as Grid service for run on the GT4 which is Grid middleware. And it provides functions which are automatic registration of database in virtual organization, distributed query service, and the unified user interface. Also this system can use components which are provided from GT4. Therefore it can improve the efficiency to distribute and manage databases, can easily access and integrate of the distributed heterogeneous data in Grid environments.

• International Journal of Advanced Culture Technology
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• v.11 no.4
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• pp.340-345
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• 2023

In recent years, the rapid development of VR technology has secured its significant position in the gaming industry. This paper selects the PC and VR versions of Resident Evil 4 as the research objects, aiming to compare the similarities and differences between these two platforms. Through this comparative study, it is evident that the PC version of the game offers most players an excellent gaming control experience through precise and flexible operations. On the other hand, the VR version not only achieves immersive gameplay through virtual reality technology but also delivers more impressive visual effects to players. However, in comparison to the traditional PC version, the VR version incurs higher development costs, necessitating the production team to invest more resources to optimize the gaming experience and strike a better balance between immersion and playability. In conclusion, this study provides a valuable reference for game developers, assisting them in meeting the diverse needs of player groups and enhancing game playability and user satisfaction.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.421-430
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• 2013

To predict behaviors of offshore wind turbines which are highly laterally loaded structures and to design them rationally, evaluating the soil-foundation interaction is important. Nowadays, there are many soil modeling methods for structural analysis of general structures subjected to vertical loads, but using the methods without any consideration for design of a monopile foundation is eschewed because it might cause wrong structural design due to the deferent loading state. In this paper, we identify the differences of the member forces and displacements by design methods. The results show that fixed end method is barely suitable for monopile design in terms of checking the serviceability because it underestimate the lateral displacement. Fixed end method and stiffness matrix method underestimate the member forces, whereas virtual fixed end method overestimates them. The results of p-y curve method and coefficient of subgrade reaction method are similar to the results of 3D soil modeling method, and 2D soil modeling method overestimates the displacement and member forces as compared with other methods.

• Archives of design research
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• v.18 no.3 s.61
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• pp.85-94
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• 2005

Most of product designers use 3D CAD system as a inevitable design tool nowadays and many new products are developed through a concurrent engineering process. However, it is very difficult for novice designers to get the sense of reality from modeling objects shown in the computer screens. Such a intangibility problem comes from the lack of haptic interactions and contextual information about the real space because designers tend to do 3D modeling works only in a virtual space of 3D CAD system. To address this problem, this research investigate the possibility of a interactive quantified structure simulation for product design using AR(augmented reality) which can register a 3D CAD modeling object on the real space. We built a quantified structure simulation system based on AR and conducted a series of experiments to measure how accurately human perceive and adjust the size of virtual objects under varied experimental conditions in the AR environment. The experiment participants adjusted a virtual cube to a reference real cube within 1.3% relative error(5.3% relative StDev). The results gave the strong evidence that the participants can perceive the size of a virtual object very accurately. Furthermore, we found that it is easier to perceive the size of a virtual object in the condition of presenting plenty of real reference objects than few reference objects, and using LCD panel than HMD. We tried to apply the simulation system to identify preference characteristics for the appearance design of a home-service robot as a case study which explores the potential application of the system. There were significant variances in participants' preferred characteristics about robot appearance and that was supposed to come from the lack of typicality of robot image. Then, several characteristic groups were segmented by duster analysis. On the other hand, it was interesting finding that participants have significantly different preference characteristics between robot with arm and armless robot and there was a very strong correlation between the height of robot and arm length as a human body.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.18-25
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• 2018

This research aims to establish the finite-element modeling techniques for computational modal analyses of liquid propellants and flange joints of launch-vehicle structures. MSC.NASTRAN is used for the present computational modal analyses of the liquid-propellant tank and the small-scaled first-stage model. By means of the correlation between the measured and computed natural frequencies, the finite modeling techniques for liquid propellants and flange joints of launch-vehicle structures are established appropriately. This modal analysis using the virtual-mass method predicts well the bell mode of the liquid-propellant tank containing liquid. In addition, the present computation using RBE2 elements for modeling of flange joints predicts the first and second bending-mode frequencies within a relative error of 10%, which is better than the measured frequencies obtained from the modal test, for the small-scaled first-stage model containing liquid.

• Korean Journal of Remote Sensing
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• v.35 no.6_4
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• pp.1391-1401
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• 2019

The KOMPSAT-3A is a high-resolution optical satellite launched in 2015 by Korea Aerospace Research Institute (KARI). KOMPSAT-3A provides Panchromatic (PAN-0.55 m), Multispectral (MS-2.2 m), and Mid-wavelength infrared (MIR_OR-5.5 m) image. However, due to security or military problems, MIR_OR image with 5.5m spatial resolution are provided down sampled at 33 m spatial resolution (MIR_rd). In this study, we propose spatial sharpening method to improve the spatial resolution of MIR_rd image (33 m) using virtual High Frequency (HF) image and optimal fusion factor. Using MS image and MIR_rd image, we generated virtual high resolution (5.5 m) MIR_OR^fus image and then compared them to actual high-resolution MIR_OR image. The test results show that the proposed method merges the spatial resolution of MS image and the spectral information of MIR_rd image efficiently.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.101-115
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• 2009

The prompt recovery of housing market in Korea became the national task, for which tools that can analyze the influence that changing situation of housing market and new policy may have on the housing market needs to be developed. Thus, this research intends to develop Multi-Agent Housing Market Model and simulation system in Jinju City as a study area. Analyzing the local housing market of Jinju City, then multi-agent model of housing market that consolidates 3 sub-models, house choice model, hedonic model of house price and location choice model is developed. Moreover in order to develop simulation system the model is programmed in the virtual space of which the size is $150{\times}100$ cell including physical shape of city such as road, urban facilities, land use, etc. With the system, simulations are performed to confirm the impact of urban development on the pattern of residential location. As a result, it is found that the residential location can not be easily induced when only road, commercial and convenient facilities are supplied. However, it is also found that since supplying green results in very many residences, arrangement of infrastructure and environmental factor should be considered at the same time for urban development. As conclusion, it is confirmed that the model and simulation system developed in this research smoothly works to be utilized for the analysis of diverse policy experiment and housing market.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.227-235
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• 2018

The aim of this study is to predict the sensitivity of motion sickness (MS) using pattern of cardinal gaze position (CGP) before experiencing the virtual reality (VR) content. Twenty volunteers of both genders (8 females, mean age $28.42{\pm}3.17$) participated in this experiment. They was required to measure the pattern of CGP for 5 minute, and then watched VR content for 15 minute. After watching VR content, subjective experience for MS reported from participants using by 'Simulator Sickness Questionnaire (SSQ)'. Statistical significance between CGP and SSQ score were confirmed using Pearson correlation analysis and independent t-test, and prediction model was extracted from multiple regression model. PCPA & PCPR indicators from CGP revealed significantly difference and strong or moderate positive correlation with SSQ score. Extracted prediction model was tested using correlation coefficient and mean error, SSQ score between subjective rating and prediction model showed strong positive correlation and low difference.