• Journal of the Korea Computer Graphics Society
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• v.30 no.3
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• pp.23-41
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• 2024

Recently, various virtual avatar music content that showcases singing and dancing have been produced, and as virtual artists gain popularity, offline virtual avatar concerts have also emerged. However, there are few examples of virtual avatar band content where avatars play instruments. In addition, offline virtual avatar concerts using large screens at the front are limited in their ability to utilize the fantastical effects and high degree of freedom unique to virtual reality. In this paper, inspired by these limitations of virtual avatar music content, we introduce the production case of virtual avatar band content and immersive interactive concert of virtual band idol Verse'day. Firstly, we present a case study on creating band performance animations and music videos using motion capture systems and real-time engines. Then, we introduce a production case of an immersive interactive concert using projection mapping technology and a light stick that allows real-time interaction in an offline concert. Finally, based on these production cases, we discussed the future research directions of developing virtual avatar music content creation. We expect that our production cases will inspire the creation of diverse virtual avatar music content and the development of immersive interactive offline virtual avatar concerts in the future.

• Journal of the Korea Computer Graphics Society
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• v.30 no.3
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• pp.81-86
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• 2024

The Image Signal Processor (ISP) converts RAW images captured by the camera sensor into user-preferred sRGB images. While RAW images contain more meaningful information for image processing than sRGB images, RAW images are rarely shared due to their large sizes. Moreover, the actual ISP process of a camera is not disclosed, making it difficult to model the inverse process. Consequently, research on learning the conversion between sRGB and RAW has been conducted. Recently, the ParamISP[1] model, which directly incorporates camera parameters (exposure time, sensitivity, aperture size, and focal length) to mimic the operations of a real camera ISP, has been proposed by advancing the simple network structures. However, existing studies, including ParamISP[1], have limitations in modeling the camera ISP as they do not consider the degradation caused by lens shading, optical aberration, and lens distortion, which limits the restoration performance. This study introduces Positional Encoding to enable the camera ISP neural network to better handle degradations caused by lens. The proposed positional encoding method is suitable for camera ISP neural networks that learn by dividing the image into patches. By reflecting the spatial context of the image, it allows for more precise image restoration compared to existing models.

• Journal of Service Research and Studies
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• v.14 no.3
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• pp.172-187
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• 2024

This paper deals with asymptotic approximations analysis of M/M/s and M/D/s queues. For M/M/s queue, we observe "economies of scale" under the fixed utilization ρ and the fixed probability α that customer waits in system, how the average system size vary according to the number of servers s increasing. Simulation results show that as s increases, the number of servers who are idling increases, that is, the slack n-E[Q_n] diverges. In addition, through changing the waiting probability α under the M/M/s system, α was not highly sensitive to the behavior of the system size. And, it is shown that using ${\rho}_n\,=\,1-k/\sqrt{n}$ to handle heavy-traffic regime is only appropriate for k = 1 by observing the effect on the performance of the system with different values of k. For the M/D/s queue, two approximations are used to evaluate the expected system size under the fixed ρ and α. Simulations and comparison of these two approximations show that Cosmetatos' approximation performs quite well when the number of servers is small and traffic intensity is heavy, but it overestimates the true value for the large number of servers. Meanwhile, the modified approximation gives good results for the steady state count of the system although the number of servers grows large.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.3
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• pp.1-13
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• 2024

This paper proposes a cost-effective system design and user-friendly approach for the key technological elements necessary to configure an autonomous mobile robot. To implement a high-precision positioning system using an autonomous mobile robot, we established a Linux-based VRS (virtual reference station)-RTK (real-time kinematic) GNSS (global navigation satellite system) system with NTRIP (Network Transport of RTCM via Internet Protocol) client functionality. Notably, we reduced the construction cost of the GNSS positioning system by performing dynamic location analysis of the established system, without utilizing an RTK replay system. Dynamic location analysis involves sampling each point during the trajectory following of the autonomous mobile robot and comparing the location precision with ground-truth points. The proposed system ensures high positioning performance with fast sampling times and suggests a GPS waypoint system for user convenience. The centimeter-level precision GNSS information is provided at a 30Hz sampling rate, and the dead reckoning function ensures valid information even when passing through tall buildings and dense forests. The horizontal position error measured through the proposed system is 6.7cm, demonstrating a highly precise dynamic location measurement error within 10cm. The VRS network-RTK Linux system, which provides precise dynamic location information at a high sampling rate, supports a GPS waypoint planner function for user convenience, enabling easy destination setting based on GPS information.

• Journal of the Korean Physical Society
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• v.80
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• pp.516-525
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• 2022

This study is to assess the clinical use of commercial PerFRACTION^TM for patient-specific quality assurance of volumetric-modulated arc therapy. Forty-six pretreatment verification plans for patients treated using a TrueBeam STx linear accelerator for lesions in various treatment sites such as brain, head and neck (H&N), prostate, and lung were included in this study. All pretreatment verification plans were generated using the Eclipse treatment planning system (TPS). Dose distributions obtained from electronic portal imaging device (EPID), ArcCHECK^TM, and two-dimensional (2D)/three-dimensional (3D) PerFRACTION^TM were then compared with the dose distribution calculated from the Eclipse TPS. In addition, the correlation between the plan complexity (the modulation complexity score and the leaf travel modulation complexity score) and the gamma passing rates (GPRs) of each quality assurance (QA) system was evaluated by calculating Spearman's rank correlation coefficient (r_s) with the corresponding p-values. The gamma passing rates of 46 patients analyzed with the 2D/3D PerFRACTION^TM using the 2%/2 mm and 3%/3 mm criteria showed almost similar trends to those analyzed with the Portal dose imaging prediction (PDIP) and ArcCHECK^TM except for those analyzed with ArcCHECK^TM using the 2%/2 mm criterion. Most of weak or moderate correlations between GPRs and plan complexity were observed for all QA systems. The trend of mean rs between GPRs using PDIP and 2D/3D PerFRACTION^TM for both criteria and plan complexity indices as in the GPRs analysis was significantly similar for brain, prostate, and lung cases with lower complexity compared to H&N case. Furthermore, the trend of mean rs for 2D/3D PerFRACTION^TM for H&N case with high complexity was similar to that of ArcCHECK^TM and slightly lower correlation was observed than that of PDIP. This work showed that the performance of 2D/3D PerFRACTION^TM for pretreatment patient-specific QA was almost comparable to that of PDIP, although there was small difference from ArcCHECK^TM for some cases. Thus, we found that the PerFRACTION^TM is a suitable QA system for pretreatment patient-specific QA in a variety of treatment sites.

• Journal of Surface Science and Engineering
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• v.57 no.4
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• pp.317-324
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• 2024

We demonstrate a direct growth of carbon nanotubes (CNTs) on the surface of LiFePO₄ (LFP) powders for use in lithium-ion batteries (LIB). LFP has been widely used as a cathode material due to its low cost and high stability. However, there is a still enough room for development to overcome its low energy density and electrical conductivity. In this study, we fabricated novel structured composites of LFP and CNTs (LFP-CNTs) and characterized the electrochemical properties of LIB. The composites were prepared by direct growth of CNTs on the surface of LFP using a rotary chemical vapor deposition. The growth temperature and rotation speed of the chamber were optimized at 600 ℃ and 5 rpm, respectively. For the LIB cell fabrication, a half-cell was fabricated using polytetrafluoroethylene (PTFE) and carbon black as binder and conductive additives, respectively. The electrochemical properties of LIBs using commercial carbon-coated LFP (LFP/C), LFP with CNTs grown for 10 (LFP/CNTs-10m) and 30 min(LFP/CNTs-30m) are comparatively investigated. For example, after the formation cycle, we obtained 149.3, 160.1, and 175.0 mAh/g for LFP/C, LFP/CNTs-10m, and LFP/CNTs-30m, respectively. In addition, the improved rate performance and 111.9 mAh/g capacity at 2C rate were achieved from the LFP/CNTs-30m sample compared to the LFP/CNTs-10m and LFP/C samples. We believe that the approach using direct growth of CNTs on LFP particles provides straightforward solution to improve the conductivity in the LFP-based electrode by constructing conduction pathways.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.4
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• pp.275-282
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• 2024

A recently proposed rapid-disassembly , carbon-minimized dismantle connection was tested using cyclic loading. To better understand the behavior of the test specimen, three-dimensional finite element (3D-FE) analyses were conducted using a "tied model" (bolted contact surfaces are tied together) and a "bolt-slip model" (contact surfaces slip and separate). The tied model suggests that plastic hinging of the beam occurs if the proposed connection behaves rigidly. The bolt-slip model suggests that the proposed connection, if manufactured and assembled properly, can dissipate energy to about 0.5 times that experienced by a rigid connection. However, when compared in a test, its moment-rotation hysteresis curve does not match well, which suggests that the low performance of the test specimen is attributable to a manufacturing deficiency. Regardless, the results corroborate the pinching phenomenon observed in the experimental hysteresis and fracture failure of the test specimen.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.61-68
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• 2024

Monitoring the injection degree of biopolymers in soils is required in estimating the performance of biopolymer-treated grounds. In this study, the degree of saturation and injection process of biopolymer solutions in sandy soils were evaluated using electrical resistivity. To assess the changes in electrical resistivity according to the contents of the biopolymer solutions, electrical resistivities were measured for Jumunjin sand-xanthan gum biopolymer solution (weight concentration of 0.5%) mixtures with different degrees of saturation of 20%, 40%, 60%, 80%, and 100%. In addition, electrical resistivities were measured at eight layers in oven-dried Jumunjin sand during the upward injection of the xanthan gum biopolymer solution to monitor the injection process. Experimental results showed that the electrical resistivity decreased as the degree of saturation of the mixture increased, and their relationship was constructed. During the injection of the xanthan gum biopolymer solution into the sandy soils, the electrical resistivity decreased and converged and the degree of saturation at each layer could be estimated on the basis of the above-constructed relationship. This study demonstrated that electrical resistivity may be an effective physical property for monitoring the injection degree of biopolymer solutions in the ground.

• Journal of Korean Society of Archives and Records Management
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• v.24 no.3
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• pp.23-44
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• 2024

In recent years, there has been a significant increase in the importance of curation services that analyze user information requests to provide tailored information within extensive information resources. This study aims to identify user information needs by analyzing search term logs from the Presidential Archives Portal to enhance the utilization value of presidential records, which possess high historical significance. In addition, by evaluating the portal's search performance, this study seeks to determine whether the Presidential Archives Portal is providing archival information services that meet users' information needs and to suggest areas for improvement through digital record curation services. To achieve these objectives, topic analysis and word network analysis were conducted based on search term logs spanning the past eight years. The search quality of the Presidential Archives Portal was evaluated from an accuracy perspective, focusing on areas with high user demand, and recommendations were drawn based on the results of the analysis. As a preliminary study for digital record curation of presidential records, this study is significant because it identifies specific user information needs and quantifies the search quality of archival portal sites to improve user satisfaction.

• Journal of Korean Society of Archives and Records Management
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• v.24 no.3
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• pp.85-104
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• 2024

While there have been ongoing discussions and attempts to utilize archives for marketing purposes in various organizations, including businesses, there has been a lack of clarity regarding what should be archived and what should be considered as marketing targets within an organization's history. Consequently, historical marketing has often been past-oriented, with results varying significantly based on the capabilities of those in charge. To introduce and effectively utilize archives in organizational settings, it is crucial to demonstrate that archives can positively impact organizational performance. The Heritage Archives is a utilization plan that offers an approach to digitizing and preserving the valuable heritage and assets of a business, explaining them to various stakeholders through records, serving as a foundation for building trust in the business, and linking them to marketing, branding, and other applications. This study focuses on fundamental concepts for constructing and utilizing heritage archives by defining and interpreting key concepts such as the affordance of records, organizational heritage, and heritage assets. To this end, the study incorporates Geoffrey Yeo's affordance and John M.T. Balmer's concept of heritage. In addition, it compares definitions of assets in KS Q ISO 55000:2021, KS X ISO 15489-1:2016, and KS X ISO 30300:2020. Through the study's findings, insights can be obtained for organizations seeking to implement heritage archives and leverage them for marketing, branding, and related purposes.