• Composites Research
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• v.37 no.1
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• pp.7-14
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• 2024

Due to the structural characteristic of a double roller, the double roller can have various deformation behaviors depending on a gap block design, even if dimensions and loading conditions for the double roller are the same. Based on this feature, we propose a strategy for designing the gap block of the carbon-fiber reinforced plastic (CFRP) double roller to minimize defects (e.g., sagging and wrinkling), which can be raised during the product conveying process, with the pursue of the lightweight design. In the suggested strategy, analysis cases are first selected by considering main design parameters and engineering tolerances of the gap block, and then deformation behaviors of these selected cases are extracted using the finite element method (FEM). Here, to obtain the optimal gap block parameters that satisfy the purpose of this study, deformation deviations in the contact area are calculated and compared using the extracted deformation behaviors. Note that the contact area in this work is located between the product and the roller. As a result, through the design method of the gap block proposed in this work, it is possible to construct the CFRP double roller that can significantly decrease the defects without changing the overall sizes of the roller. A detailed method is suggested herein, and the results are evaluated in a numerical way.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.3
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• pp.46-55
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• 2016

This work proposes a 13b 100MS/s 45nm CMOS ADC with a high dynamic performance for IF-domain high-speed signal processing systems based on a four-step pipeline architecture to optimize operating specifications. The SHA employs a wideband high-speed sampling network properly to process high-frequency input signals exceeding a sampling frequency. The SHA and MDACs adopt a two-stage amplifier with a gain-boosting technique to obtain the required high DC gain and the wide signal-swing range, while the amplifier and bias circuits use the same unit-size devices repeatedly to minimize device mismatch. Furthermore, a separate analog power supply voltage for on-chip current and voltage references minimizes performance degradation caused by the undesired noise and interference from adjacent functional blocks during high-speed operation. The proposed ADC occupies an active die area of $0.70mm^2$, based on various process-insensitive layout techniques to minimize the physical process imperfection effects. The prototype ADC in a 45nm CMOS demonstrates a measured DNL and INL within 0.77LSB and 1.57LSB, with a maximum SNDR and SFDR of 64.2dB and 78.4dB at 100MS/s, respectively. The ADC is implemented with long-channel devices rather than minimum channel-length devices available in this CMOS technology to process a wide input range of $2.0V_{PP}$ for the required system and to obtain a high dynamic performance at IF-domain input signal bands. The ADC consumes 425.0mW with a single analog voltage of 2.5V and two digital voltages of 2.5V and 1.1V.

• Information Systems Review
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• v.25 no.4
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• pp.131-159
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• 2023

Recently, amidst the backdrop of the COVID-19 pandemic shifting towards an endemic phase, there has been a rise in discussions and debates about the future of the metaverse. Simultaneously, major metaverse platforms like Roblox have been launching services integrated with generative AI, and Apple's mixed reality hardware, Vision Pro, has been announced, creating new expectations for the metaverse. In this situation where the outlook for the metaverse is divided, it is crucial to diagnose the metaverse from an ecosystem perspective, examine its key ecological features, driving forces for development, and future possibilities for advancement. This study utilized Wang's (2021) Information Ecology Theory (IET) framework, which is representative of ecosystem research in the field of Information Systems (IS), to derive the Metaverse Industrial Ecosystem (MIE). The analysis revealed that the MIE consists of four main domains: Tech Landscape, Category Ecosystem, Metaverse Platform, and Product/Service Ecosystem. It was found that the MIE exhibits characteristics such as digital connectivity, the integration of real and virtual worlds, value creation capabilities, and value sharing (Web 3.0). Furthermore, the interactions among the domains within the MIE and the four characteristics of the ecosystem were identified as driving forces for the development of the MIE at an ecosystem level. Additionally, the development of the MIE at an ecosystem level was categorized into three distinct stages: Narrow Ecosystem, Expanded Ecosystem, and Everywhere Ecosystem. It is anticipated that future advancements in related technologies and industries, such as robotics, AI, and 6G, will promote the transition from the current Expanded Ecosystem level of the MIE to an Everywhere Ecosystem level, where the connection between the real and virtual worlds is pervasive. This study provides several implications. Firstly, it offers a foundational theory and analytical framework for ecosystem research, addressing a gap in previous metaverse studies. It also presents various research topics within the metaverse domain. Additionally, it establishes an academic foundation that integrates concept definition research and impact studies, which are key areas in metaverse research. Lastly, referring to the developmental stages and conditions proposed in this study, businesses and governments can explore future metaverse markets and related technologies. They can also consider diverse metaverse business strategies. These implications are expected to guide the exploration of the emerging metaverse market and facilitate the evaluation of various metaverse business strategies.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.4
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• pp.412-429
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• 2008

As the amount of electronic documents increases rapidly with the growth of the Internet, a parallel search engine capable of handling a large number of documents are becoming ever important. To implement a parallel search engine, we need to partition the inverted index and search through the partitioned index in parallel. There are two methods of partitioning the inverted index: 1) document-identifier based partitioning and 2) keyword-identifier based partitioning. However, each method alone has the following drawbacks. The former is convenient in inserting documents and has high throughput, but has poor performance for top h query processing. The latter has good performance for top-k query processing, but is inconvenient in inserting documents and has low throughput. In this paper, we propose a hybrid partitioning method to compensate for the drawback of each method. We design and implement a parallel search engine that supports the hybrid partitioning method using the Odysseus DBMS tightly coupled with information retrieval capability. We first introduce the architecture of the parallel search engine-Odysseus/parallel-OOSQL. We then show the effectiveness of the proposed system through systematic experiments. The experimental results show that the query processing time of the document-identifier based partitioning method is approximately inversely proportional to the number of blocks in the partition of the inverted index. The results also show that the keyword-identifier based partitioning method has good performance in top-k query processing. The proposed parallel search engine can be optimized for performance by customizing the methods of partitioning the inverted index according to the application environment. The Odysseus/parallel OOSQL parallel search engine is capable of indexing, storing, and querying 100 million web documents per node or tens of billions of web documents for the entire system.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.345-351
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• 2015

Purpose: The purpose of this study was to evaluate the proper axial thickness of zirconia abutment applied to implant in the anterior region. Materials and methods: Zirconia abutments were prepared at different axial wall thickness by processing pre-sintered zirconia blocks via CAD/CAM to obtain equal specimens. The abutments were each produced with a thickness of 0.5 mm (Group 1), 0.8 mm (Group 2), 1.2 mm (Group 3), or 1.5 mm (Group 4). The implant used in this study was a external connection type one (US, Osstem, Pussan, Korea) product and the zirconia abutment was prepared via replication of a cemented abutment. The crowns were prepared via CAM/CAM with a thickness of 1.5 mm and were cemented to the abutments using $RelyX^{TM}$ UniCem cement. A universal testing machine was used to apply load at 30 degrees and measure fracture strength of the zirconia abutment. Results: Fracture strength of the abutments for Group 1, Group 2, Group 3, and Group 4 were $236.00{\pm}67.55N$, $599.00{\pm}15.80N$, $588.20{\pm}33.18N$, and $97.83{\pm}98.13N$, respectively. Group 1 showed a significantly lower value, as compared to the other groups (independent Mann-Whitney U-test. P<.05). No significant differences were detected among Group 2, Group 3, and Group 4 (independent Mann-Whitney U-test. P>.05). Conclusion: Zirconia abutment requires optimal thickness for fracture resistance. Within the limitation of this study, > 0.8 mm thickness is recommended for zirconia abutment in anterior implants.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.530-541
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• 2007

Currently, various Nickel-Titanium rotary files are used in endodontic treatment, but there is no one perfect system that can be applied to any clinical situation. Therefore, the combined uses of various file systems which can emphasize the advantages of each system are introduced as hybrid instrumentation. The ProTaper system is efficient in body shaping and apical pre-enlargement but is reported to have more possibility of transportation and produce more aberrations and deformation in more or less severe curved canals. Recently, new ProTaper system(ProTaper Universal) with different configuration and cross-sectional design to overcome the week points of ProTaper have been marketed. The purpose of this study was to compare and evaluate the shaping abilities of ProTaper, ProTaper Universal system, and two hybrid methods using S-series of ProTaper Universal and Hero Shaper or ProFile. The time lapses for instrumentation were measured and the used files were inspected for distortion. The pre- and post-instrumented root canals were scanned and superimposed to evaluate the aberrations and reduction of root canal curvature and change of radius of canal curvature. The increased canal width and apical centering ratio were calculated at 1, 2, 3, 4 and 5 mm levels from apical foramen. Under the conditions of this study, the ProTaper Universal seems to have better shaping ability than ProTaper in terms of instrumented width and instrumentation time. It may be suggested that the ProTaper Universal system is efficient as much as hybrid instrumentation using ProTaper and other constant-tapered NiTi file systems in highly experienced operators.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.947-953
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• 2005

Previous test results showed that the current ASTM(American Standard for Testing and Materials) grip adapter for GFRP(Glass Fiber Reinforced Polymer) rebar was not fully successful in developing the design tensile strength of GFRP rebars with reasonable accuracy. It is because the current ASTM grip adapter which is composed of a pair of rectangular metal blocks of which inner faces are grooved along the longitudinal direction does not take into account the various geometric characteristics of GFRP rebar such as surface treatment, shape of bar cross section as well as physical characteristics such as poisson effect, elastic modulus in the transverse direction and so on. The objective of this paper is to provide how to proportion the optimum diameter of inner groove in ASTM grip adapter to develop design tensile strength of GFRP rebar. The proportioning of inner groove in ASTM grip adapter is based on the force equilibrium of GFRP rebar between tensile capacity and minimum frictional resistance required along the grip adapter. The frictional resistance of grip adapter is calculated based on the compressive strain compatibility in radial direction induced by the difference between diameter of GFRP rebar and inner groove In ASTM grip. All testing procedures were made according to the CSA S806-02 recommendations. From the preliminary test results on round-type GFRP rebars, it was found that maximum tensile loads acquired under the same testing conditions is highly affected by the diameter of inner groove in ASTM grip adapter. The grip adapter with specific dimension proportioned by proposed method recorded the highest tensile strength among them.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.2
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• pp.73-81
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• 2013

Purpose: The purpose of this study was to evaluate the effect of surface treatment on the shear bond strength of zirconia ceramic to 3 resin cements. Materials and methods: A total of 143 disk-shaped Zirconia blocks (HASS Co., Gangneung, Korea) were randomly divided into three treatment groups: (1) only 50 ${\mu}m$ $Al_2O_3$ sandblasting, (2) 50 ${\mu}m$ $Al_2O_3$ sandblast and zircona liner, (3) 50 ${\mu}m$ $Al_2O_3$ sandblasting and Rocatec (3M ESPE, Seefeld, Germany). Bistite II (Tokuyama Dental Co., Japan), Panavia F (Kuraray Medical, Japan), and Superbond C&B (Sun Medical, Japan) were used to cement onto the zirconia. After 24h of storage in distilled water, shear bond strength was evaluated. High value group was re-tested after thermocycling at 5,000 cycles(5-$55^{\circ}C$). Shear bond strength data were analyzed with one-way ANOVA, two-way ANOVA test and Post Hoc Test (${\alpha}$=.05). Shear bond strength data before and after thermocycling were analyzed with Independent sample T test (${\alpha}$=.05). Results: Super-bond C&B treated with Rocatec showed the most high shear bond strength. Super-bond C&B groups resulted in significantly higher than other cement groups (P<.05). Rocatec groups resulted in significantly higher than other surface treatment groups (P<.05). Shear bond strength has increased in Panavia F treated with Zirconia liner (P<.05). After thermocycling, shear bond strength was increased in Super-bond C&B treated with Rocatec but decreased in other groups (P<.05). Conclusion: Super-bond C&B cement resulted the highest shear bond strength and Rocatec system enhanced the shear bond strength. After thermocycling, shear bond strength has decreased in most resin cements except Super-bond C&B treated with Rocatec.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.176-188
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• 2018

Modern urban problems are increasingly becoming a market mix that can not be solved by the power of a single department and the necessity of establishing a cooperation system based on data communication between departments is increasing. Therefore, this study analyzed Busan metropolitan city's IT projects from 2014 to 2018 in order to understand the utilization and sharing status of departmental data from the viewpoint that cooperation between departments can start from the sharing of data with high common utilization. In addition, based on the results of the FGI(Focus Group Interview) conducted for the officials of the department responsible for the informatization project, we verified the results of data status analysis. At the same time, we figured out the necessity of data link between departments through SNA(Social Network Analysis) and presented data that should be shared first in the future. As a result, most of the information systems currently use limited data only within the department that produced the data. Most of the linked data was concentrated in the information department. Therefore, this study suggested the following solutions. First, in order to prevent overlapping investments caused by the operation of individual departments and share information, it is necessary to build a small platform to tie the departments, which have high connectivity with each other, into small blocks. Second, a local level process is needed to develop data standards as an extension of national standards in order to expand the information to be used in various fields. Third, as another solution, we proposed a system that can integrate various types of information based on address and location information through application of cloud-based GIS platform. The results of this study are expected to contribute to build a cooperation system between departments through expansion of information sharing with cost reduction.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.16-22
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• 2014

Purpose: The purpose of this study was to assess the marginal and mesial fitness of zirconia single copings and 3-unit fixed partial dentures (FPDs) manufactured with an identical model. Materials and Methods: An epoxy model in which the maxillary right 2nd premolar is lost and maxillary 1st premolar and 2nd molar are formed as abutments was manufactured and scanned by using a laser scanner. A ten units of zirconia single copings were manufactured for maxillary 1st premolar and 2nd molar, respectively and the same number of 3-unit FPDs were manufactured. For the measurements of fitness, the manufactured silicone replicas were divided into four parts and the fitness were measured by digital microscope at measurement points (P1, P2, P3, P4 and P5) of each plane. The measured gaps were classified into three categories: marginal gap (MG, P1), axial gap (AG, average of P2 and P3), occlusal gap (OG, average of P4 and P5). Results: The ranges of MG, AG and OG for single copings were 18.47 - 40.54 ${\mu}m$, 39.73 - 73.61 ${\mu}m$ and 116.90 - 134.69 ${\mu}m$, respectively. The ranges of MG, AG and OG for 3-unit FPDs were 45.95 - 87.44 ${\mu}m$, 23.78 - 57.00 ${\mu}m$ and 99.89 - 131.06 ${\mu}m$, respectively. Conclusion: The result of the study shows that the MGs for 3-unit FPDs were higher than those of single copings, though they are within the range of clinical acceptance, indicating that the use of more homogeneous zirconia block and modification of sintering processes are needed to ensure the prevention of increase of gap in 3-unit FPDs.