• Title/Summary/Keyword: Effective Space Use

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Improved Resource Allocation Model for Reducing Interference among Secondary Users in TV White Space for Broadband Services

  • Marco P. Mwaimu;Mike Majham;Ronoh Kennedy;Kisangiri Michael;Ramadhani Sinde
    • International Journal of Computer Science & Network Security
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    • v.23 no.4
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    • pp.55-68
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    • 2023
  • In recent years, the Television White Space (TVWS) has attracted the interest of many researchers due to its propagation characteristics obtainable between 470MHz and 790MHz spectrum bands. The plenty of unused channels in the TV spectrum allows the secondary users (SUs) to use the channels for broadband services especially in rural areas. However, when the number of SUs increases in the TVWS wireless network the aggregate interference also increases. Aggregate interferences are the combined harmful interferences that can include both co-channel and adjacent interferences. The aggregate interference on the side of Primary Users (PUs) has been extensively scrutinized. Therefore, resource allocation (power and spectrum) is crucial when designing the TVWS network to avoid interferences from Secondary Users (SUs) to PUs and among SUs themselves. This paper proposes a model to improve the resource allocation for reducing the aggregate interface among SUs for broadband services in rural areas. The proposed model uses joint power and spectrum hybrid Firefly algorithm (FA), Genetic algorithm (GA), and Particle Swarm Optimization algorithm (PSO) which is considered the Co-channel interference (CCI) and Adjacent Channel Interference (ACI). The algorithm is integrated with the admission control algorithm so that; there is a possibility to remove some of the SUs in the TVWS network whenever the SINR threshold for SUs and PU are not met. We considered the infeasible system whereby all SUs and PU may not be supported simultaneously. Therefore, we proposed a joint spectrum and power allocation with an admission control algorithm whose better complexity and performance than the ones which have been proposed in the existing algorithms in the literature. The performance of the proposed algorithm is compared using the metrics such as sum throughput, PU SINR, algorithm running time and SU SINR less than threshold and the results show that the PSOFAGA with ELGR admission control algorithm has best performance compared to GA, PSO, FA, and FAGAPSO algorithms.

How do people verify identity in the Metaverse: Through exploring the user's avatar (메타버스 내 아바타 정체성 확인에 영향을 미치는 요인에 관한 연구)

  • Kihyun Kim;Seongwon Lee;Kil-Soo Suh
    • Journal of Intelligence and Information Systems
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    • v.29 no.2
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    • pp.189-217
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    • 2023
  • The metaverse is a virtual world where individuals engage in social, economic, and cultural activities using avatars, which represent an alternate version of oneself within the virtual realm. While the metaverse has garnered global attention recently, research exploring the identity manifested through avatars within the metaverse remains limited. This study investigates the influence of four IT artifact characteristics related to avatar usage in the metaverse-avatar representation, avatar copresence, avatar profiling, and avatar-space interaction-on perceived avatar identity verification. A survey was conducted with 196 experienced users of the Zepeto platform, and hypotheses were tested using structural equation modeling. The analysis results indicate that the use of IT artifacts enabling avatar representation, avatar copresence, and avatar-space interaction has a positive impact on perceived avatar identity verification. This achieved self-verification indirectly influences the satisfaction and subsequent intention to continue using the metaverse. This study contributes to the academic field by empirically verifying the metaverse technological factors that influence the projected identity onto avatars within the metaverse. Furthermore, it is expected to provide effective guidelines for metaverse platform companies in designing and implementing the metaverse.

A Study on User Perception Survey for Establishing Effective Operational Strategies of the Gwacheon City Library (과천시 도서관의 효과적인 운영 방안 수립을 위한 이용자 인식조사 연구)

  • Younghee Noh;Inho Chang;Woojung Kwak
    • Journal of the Korean BIBLIA Society for library and Information Science
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    • v.35 no.1
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    • pp.73-96
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    • 2024
  • This study aimed to establish a systematic and comprehensive operational plan for the library to be constructed in the Gwacheon Knowledge Information Town. To achieve this, a survey on the demand for library operations was conducted among actual users of the Gwacheon City Public Library, and plans for the library collection development, user services, and methods to revitalize use were formulated based on the survey results. The findings are as follows. First, the library's construction/space analysis results suggest the need for a multifunctional cultural space accessible to everyone, serving as both a relaxation area and venue for a free information exchange and communication, allowing for a certain level of noise to facilitate an open atmosphere for users. Second, the analysis of the preferred types and forms of library materials revealed that printed materials ranked first, followed by web resources in the second place, and e-books/e-journals in the third. Additionally, there was a high preference for subjects such as literature and history. Third, a high preference was observed for cultural and arts programs, indicating the need for the future Gwacheon Knowledge Information Town Library to strengthen and implement programs focusing on cultural and artistic themes.

The Prediction of DEA based Efficiency Rating for Venture Business Using Multi-class SVM (다분류 SVM을 이용한 DEA기반 벤처기업 효율성등급 예측모형)

  • Park, Ji-Young;Hong, Tae-Ho
    • Asia pacific journal of information systems
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    • v.19 no.2
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    • pp.139-155
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    • 2009
  • For the last few decades, many studies have tried to explore and unveil venture companies' success factors and unique features in order to identify the sources of such companies' competitive advantages over their rivals. Such venture companies have shown tendency to give high returns for investors generally making the best use of information technology. For this reason, many venture companies are keen on attracting avid investors' attention. Investors generally make their investment decisions by carefully examining the evaluation criteria of the alternatives. To them, credit rating information provided by international rating agencies, such as Standard and Poor's, Moody's and Fitch is crucial source as to such pivotal concerns as companies stability, growth, and risk status. But these types of information are generated only for the companies issuing corporate bonds, not venture companies. Therefore, this study proposes a method for evaluating venture businesses by presenting our recent empirical results using financial data of Korean venture companies listed on KOSDAQ in Korea exchange. In addition, this paper used multi-class SVM for the prediction of DEA-based efficiency rating for venture businesses, which was derived from our proposed method. Our approach sheds light on ways to locate efficient companies generating high level of profits. Above all, in determining effective ways to evaluate a venture firm's efficiency, it is important to understand the major contributing factors of such efficiency. Therefore, this paper is constructed on the basis of following two ideas to classify which companies are more efficient venture companies: i) making DEA based multi-class rating for sample companies and ii) developing multi-class SVM-based efficiency prediction model for classifying all companies. First, the Data Envelopment Analysis(DEA) is a non-parametric multiple input-output efficiency technique that measures the relative efficiency of decision making units(DMUs) using a linear programming based model. It is non-parametric because it requires no assumption on the shape or parameters of the underlying production function. DEA has been already widely applied for evaluating the relative efficiency of DMUs. Recently, a number of DEA based studies have evaluated the efficiency of various types of companies, such as internet companies and venture companies. It has been also applied to corporate credit ratings. In this study we utilized DEA for sorting venture companies by efficiency based ratings. The Support Vector Machine(SVM), on the other hand, is a popular technique for solving data classification problems. In this paper, we employed SVM to classify the efficiency ratings in IT venture companies according to the results of DEA. The SVM method was first developed by Vapnik (1995). As one of many machine learning techniques, SVM is based on a statistical theory. Thus far, the method has shown good performances especially in generalizing capacity in classification tasks, resulting in numerous applications in many areas of business, SVM is basically the algorithm that finds the maximum margin hyperplane, which is the maximum separation between classes. According to this method, support vectors are the closest to the maximum margin hyperplane. If it is impossible to classify, we can use the kernel function. In the case of nonlinear class boundaries, we can transform the inputs into a high-dimensional feature space, This is the original input space and is mapped into a high-dimensional dot-product space. Many studies applied SVM to the prediction of bankruptcy, the forecast a financial time series, and the problem of estimating credit rating, In this study we employed SVM for developing data mining-based efficiency prediction model. We used the Gaussian radial function as a kernel function of SVM. In multi-class SVM, we adopted one-against-one approach between binary classification method and two all-together methods, proposed by Weston and Watkins(1999) and Crammer and Singer(2000), respectively. In this research, we used corporate information of 154 companies listed on KOSDAQ market in Korea exchange. We obtained companies' financial information of 2005 from the KIS(Korea Information Service, Inc.). Using this data, we made multi-class rating with DEA efficiency and built multi-class prediction model based data mining. Among three manners of multi-classification, the hit ratio of the Weston and Watkins method is the best in the test data set. In multi classification problems as efficiency ratings of venture business, it is very useful for investors to know the class with errors, one class difference, when it is difficult to find out the accurate class in the actual market. So we presented accuracy results within 1-class errors, and the Weston and Watkins method showed 85.7% accuracy in our test samples. We conclude that the DEA based multi-class approach in venture business generates more information than the binary classification problem, notwithstanding its efficiency level. We believe this model can help investors in decision making as it provides a reliably tool to evaluate venture companies in the financial domain. For the future research, we perceive the need to enhance such areas as the variable selection process, the parameter selection of kernel function, the generalization, and the sample size of multi-class.

Effect of Implant Types and Bone Resorption on the Fatigue Life and Fracture Characteristics of Dental Implants (임플란트 형태와 골흡수가 임플란트 피로 수명 및 파절 특성에 미치는 효과에 관한 연구)

  • Won, Ho-Yeon;Choi, Yu-Sung;Cho, In-Ho
    • Journal of Dental Rehabilitation and Applied Science
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    • v.26 no.2
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    • pp.121-143
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    • 2010
  • To investigate the effect of implant types and bone resorption on the fracture characteristics. 4 types of Osstem$^{(R)}$Implant were chosen and classified into external parallel, internal parallel, external taper, internal taper groups. Finite elements analysis was conducted with ANSYS Multi Physics software. Fatigue fracture test was performed by connecting the mold to the dynamic load fatigue testing machine with maximum load of 600N and minimum load of 60N. The entire fatigue test was performed with frequency of 14Hz and fractured specimens were observed with Hitachi S-3000 H scanning electron microscope. The results were as follows: 1. In the fatigue test of 2 mm exposed implants group, Tapered type and external connected type had higher fatigue life. 2. In the fatigue test of 4 mm exposed implants group, Parallel type and external connected types had higher fatigue life. 3. The fracture patterns of all 4 mm exposed implant system appeared transversely near the dead space of the fixture. With a exposing level of 2 mm, all internally connected implant systems were fractured transversely at the platform of fixture facing the abutment. but externally connected ones were fractured at the fillet of abutment body and hexa of fixture or near the dead space of the fixture. 4. Many fatigue striations were observed near the crack initiation and propagation sites. The cleavage with facet or dimple fractures appeared at the final fracture sites. 5. Effective stress of buccal site with compressive stress is higher than that of lingual site with tensile stress, and effective stress acting on the fixture is higher than that of the abutment screw. Also, maximum effective stress acting on the parallel type fixtures is higher. It is careful to use the internal type implant system in posterior area.

Exploring the 4th Industrial Revolution Technology from the Landscape Industry Perspective (조경산업 관점에서 4차 산업혁명 기술의 탐색)

  • Choi, Ja-Ho;Suh, Joo-Hwan
    • Journal of the Korean Institute of Landscape Architecture
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    • v.47 no.2
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    • pp.59-75
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    • 2019
  • This study was carried out to explore the 4th Industrial Revolution technology from the perspective of the landscape industry to provide the basic data necessary to increase the virtuous circle value. The 4th Industrial Revolution, the characteristics of the landscape industry and urban regeneration were considered and the methodology was established and studied including the technical classification system suitable for systematic research, which was selected as a framework. First, the 4th Industrial Revolution technology based on digital data was selected, which could be utilized to increase the value of the virtuous circle for the landscape industry. From 'Element Technology Level', and 'Core Technology' such as the Internet of Things, Cloud Computing, Big Data, Artificial Intelligence, Robot, 'Peripheral Technology', Virtual or Augmented Reality, Drones, 3D 4D Printing, and 3D Scanning were highlighted as the 4th Industrial Revolution technology. It has been shown that it is possible to increase the value of the virtuous circle when applied at the 'Trend Level', in particular to the landscape industry. The 'System Level' was analyzed as a general-purpose technology, and based on the platform, the level of element technology(computers, and smart devices) was systematically interconnected, and illuminated with the 4th Industrial Revolution technology based on digital data. The application of the 'Trend Level' specific to the landscape industry has been shown to be an effective technology for increasing the virtuous circle values. It is possible to realize all synergistic effects and implementation of the proposed method at the trend level applying the element technology level. Smart gardens, smart parks, etc. have been analyzed to the level they should pursue. It was judged that Smart City, Smart Home, Smart Farm, and Precision Agriculture, Smart Tourism, and Smart Health Care could be highly linked through the collaboration among technologies in adjacent areas at the Trend Level. Additionally, various utilization measures of related technology applied at the Trend Level were highlighted in the process of urban regeneration, public service space creation, maintenance, and public service. In other words, with the realization of ubiquitous computing, Hyper-Connectivity, Hyper-Reality, Hyper-Intelligence, and Hyper-Convergence were proposed, reflecting the basic characteristics of digital technology in the landscape industry can be achieved. It was analyzed that the landscaping industry was effectively accommodating and coordinating with the needs of new characters, education and consulting, as well as existing tasks, even when participating in urban regeneration projects. In particular, it has been shown that the overall landscapig area is effective in increasing the virtuous circle value when it systems the related technology at the trend level by linking maintenance with strategic bridgehead. This is because the industrial structure is effective in distributing data and information produced from various channels. Subsequent research, such as demonstrating the fusion of the 4th Industrial Revolution technology based on the use of digital data in creation, maintenance, and service of actual landscape space is necessary.

Applicability of Multi-Temporal MODIS Images for Drought Assessment in South Korea (봄 가뭄 평가를 위한 다중시기 MODIS 영상의 적용성 분석)

  • Park, Jung-Sool;Kim, Kyung-Tak;Lee, Jin-Hee;Lee, Kyu-Sung
    • Journal of the Korean Association of Geographic Information Studies
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    • v.9 no.4
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    • pp.176-192
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    • 2006
  • The need for a systematic drought management has increased since last countrywide drought in 2001. Naturally various studies for establishing drought plan and preventing drought disaster have been conducted. MODIS image provided by Terra satellite has effective spatial and temporal resolutions to observe spatial and temporal characteristics of a region. MODIS data products are easy for preprocessing and correcting geometrically and provide various data set in regular which are applicable for drought monitoring. In this study, Ansung river and the upstream of South Han river basin was chosen for case study to identify and assess spring drought. The multi-period MODIS image and accumulated precipitation were used to detect not only the drought year but also the vegetation change of normal year and the result were compared with various spatial data. The result shows NDVI and LSWI with is more appropriate than LST for assesing spring drought in Korea and two month cumulative precipitation has moderate relationship with drought. It is necessary to use MODIS image which has same period and same space for effective drought analysis because drought is also affected by landover and altitude.

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Determination of Key Factors for the Pedestrian LOS Introducing the Accessibility Index (접근성 지표를 도입한 보행로 서비스 수준의 영향요인 규명)

  • CHOI, Sung Taek;CHOO, Sang Ho;JANG, Jin Young
    • Journal of Korean Society of Transportation
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    • v.33 no.6
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    • pp.584-597
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    • 2015
  • A considerable amount of literature has been published on pedestrian LOS. So far, however, there is a limitation that LOS analysis methodologies has concentrated on quantitative variables such as pedestrian flow rate, speed and space. This paper intended to suggest the accessibility variable which can not be considered on previous study. The factor was defined and quantified using public transport attributes in particular. This study was carried out in three phases: 1. defined accessibility employing public mode location and service information. 2. investigated the relationship between accessibility and pedestrian flow rate 3. developed the model to establish the factors affected to pedestrian LOS. The results showed that accessibility, walkway attribute and land use type affected the pedestrian LOS. Especially, accessibility and commercial area ratio had negative relationship with LOS. Futhermore, pedestrian LOS declined when obstacle of bus station located on the walkway. On the contrary, LOS was upgraded when sufficient effective width or residential area was secured. These results can receive considerable critical attentions related to determination of pedestrian LOS or effective walkway width.

Estimation of Leaf Area Index Based on Machine Learning/PROSAIL Using Optical Satellite Imagery (광학위성영상을 이용한 기계학습/PROSAIL 모델 기반 엽면적지수 추정)

  • Lee, Jaese;Kang, Yoojin;Son, Bokyung;Im, Jungho;Jang, Keunchang
    • Korean Journal of Remote Sensing
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    • v.37 no.6_1
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    • pp.1719-1729
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    • 2021
  • Leaf area index (LAI) provides valuable information necessary for sustainable and effective management of forests. Although global high resolution LAI data are provided by European Space Agency using Sentinel-2 satellite images, they have not considered forest characteristics in model development and have not been evaluated for various forest ecosystems in South Korea. In this study, we proposed a LAI estimation model combining machine learning and the PROSAIL radiative transfer model using Sentinel-2 satellite data over a local forest area in South Korea. LAI-2200C was used to measure in situ LAI data. The proposed LAI estimation model was compared to the existing Sentinel-2 LAI product. The results showed that the proposed model outperformed the existing Sentinel-2 LAI product, yielding a difference of bias ~ 0.97 and a difference of root-mean-square-error ~ 0.81 on average, respectively, which improved the underestimation of the existing product. The proposed LAI estimation model provided promising results, implying its use for effective LAI estimation over forests in South Korea.

Evaluation of Woodchip and Synthetic Fiber as Biofilter Media for the Treatment of Livestock Stormwater (가축사육단지 강우유출수 처리목적 바이오 필터 여재로서 우드칩과 합성섬유의 평가)

  • Cheng, Jing;Guerra, Heidi B.;Kim, Youngchul
    • Journal of Wetlands Research
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    • v.23 no.1
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    • pp.94-105
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    • 2021
  • Two vertical flow biofilters in series (BFS) employing synthetic fiber (FBF) followed by woodchip (WBF) was investigated in order to assess its potential as an alternative to the typical vertical-horizontal flow configuration in removing nonpoint source pollutants specifically nutrients and organics. These lab-scale column biofilters were operated for 176 days alongside three other columns that were added for control and sampling purposes. The biofilter columns were fed with either a semi-artificial piggery stormwater or artificial stormwater with specific ammonia and nitrate contents. Results reveal that the BFS was more effective than a single biofilter in removing pollutants especially nitrogen. FBF was found to remove up to 100% of ammonia from the stormwater with corresponding increase in nitrate in the outflow which shows evidence of active nitrification. Meanwhile, the succeeding vertical WBF was able to subsequently remove 77% of the nitrate. The effective reduction of nitrate in a vertical flow biofilter was believed to be due to the use of woodchip which can provide a carbon source that is required for denitrification. However, further investigation is needed to support this claim. Nonetheless, the study shows the potential of vertical flow BFS as a nitrogen removal mechanism especially in areas where enough land space for horizontal flow biofilters is limited.