• Title/Summary/Keyword: Virtual model

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Simulation of Time-Domain Acoustic Wave Signals Backscattered from Underwater Targets (수중표적의 시간영역 음파 후방산란 신호 모의)

  • Kim, Kook-Hyun;Cho, Dae-Seung;Seong, Woo-Jae
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.3
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    • pp.140-148
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    • 2008
  • In this study, a numerical method for a time-domain acoustic wave backscattering analysis is established based on a physical optics and a Fourier transform. The frequency responses of underwater targets are calculated based on physical optics derived from the Kirchhoff-Helmholtz integral equation by applying Kirchhoff approximation and the time-domain signals are simulated taking inverse fast Fourier transform to the obtained frequency responses. Particularly, the adaptive triangular beam method is introduced to calculate the areas impinged directly by acoustic incident wave and the virtual surface concept is adopted to consider the multiple reflection effect. The numerical analysis result for an acoustic plane wave field incident normally upon a square flat plate is coincident with the result by the analytic time-domain physical optics derived theoretically from a conventional physical optics. The numerical simulation result for a hemi-spherical end-capped cylinder model is compared with the measurement result, so that it is recognized that the presented method is valid when the specular reflection effect is predominant, but, for small targets, gives errors due to higher order scattering components. The numerical analysis of an idealized submarine shows that the established method is effectively applicable to large and complex-shaped underwater targets.

A Store Recommendation Procedure in Ubiquitous Market for User Privacy (U-마켓에서의 사용자 정보보호를 위한 매장 추천방법)

  • Kim, Jae-Kyeong;Chae, Kyung-Hee;Gu, Ja-Chul
    • Asia pacific journal of information systems
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    • v.18 no.3
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    • pp.123-145
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    • 2008
  • Recently, as the information communication technology develops, the discussion regarding the ubiquitous environment is occurring in diverse perspectives. Ubiquitous environment is an environment that could transfer data through networks regardless of the physical space, virtual space, time or location. In order to realize the ubiquitous environment, the Pervasive Sensing technology that enables the recognition of users' data without the border between physical and virtual space is required. In addition, the latest and diversified technologies such as Context-Awareness technology are necessary to construct the context around the user by sharing the data accessed through the Pervasive Sensing technology and linkage technology that is to prevent information loss through the wired, wireless networking and database. Especially, Pervasive Sensing technology is taken as an essential technology that enables user oriented services by recognizing the needs of the users even before the users inquire. There are lots of characteristics of ubiquitous environment through the technologies mentioned above such as ubiquity, abundance of data, mutuality, high information density, individualization and customization. Among them, information density directs the accessible amount and quality of the information and it is stored in bulk with ensured quality through Pervasive Sensing technology. Using this, in the companies, the personalized contents(or information) providing became possible for a target customer. Most of all, there are an increasing number of researches with respect to recommender systems that provide what customers need even when the customers do not explicitly ask something for their needs. Recommender systems are well renowned for its affirmative effect that enlarges the selling opportunities and reduces the searching cost of customers since it finds and provides information according to the customers' traits and preference in advance, in a commerce environment. Recommender systems have proved its usability through several methodologies and experiments conducted upon many different fields from the mid-1990s. Most of the researches related with the recommender systems until now take the products or information of internet or mobile context as its object, but there is not enough research concerned with recommending adequate store to customers in a ubiquitous environment. It is possible to track customers' behaviors in a ubiquitous environment, the same way it is implemented in an online market space even when customers are purchasing in an offline marketplace. Unlike existing internet space, in ubiquitous environment, the interest toward the stores is increasing that provides information according to the traffic line of the customers. In other words, the same product can be purchased in several different stores and the preferred store can be different from the customers by personal preference such as traffic line between stores, location, atmosphere, quality, and price. Krulwich(1997) has developed Lifestyle Finder which recommends a product and a store by using the demographical information and purchasing information generated in the internet commerce. Also, Fano(1998) has created a Shopper's Eye which is an information proving system. The information regarding the closest store from the customers' present location is shown when the customer has sent a to-buy list, Sadeh(2003) developed MyCampus that recommends appropriate information and a store in accordance with the schedule saved in a customers' mobile. Moreover, Keegan and O'Hare(2004) came up with EasiShop that provides the suitable tore information including price, after service, and accessibility after analyzing the to-buy list and the current location of customers. However, Krulwich(1997) does not indicate the characteristics of physical space based on the online commerce context and Keegan and O'Hare(2004) only provides information about store related to a product, while Fano(1998) does not fully consider the relationship between the preference toward the stores and the store itself. The most recent research by Sedah(2003), experimented on campus by suggesting recommender systems that reflect situation and preference information besides the characteristics of the physical space. Yet, there is a potential problem since the researches are based on location and preference information of customers which is connected to the invasion of privacy. The primary beginning point of controversy is an invasion of privacy and individual information in a ubiquitous environment according to researches conducted by Al-Muhtadi(2002), Beresford and Stajano(2003), and Ren(2006). Additionally, individuals want to be left anonymous to protect their own personal information, mentioned in Srivastava(2000). Therefore, in this paper, we suggest a methodology to recommend stores in U-market on the basis of ubiquitous environment not using personal information in order to protect individual information and privacy. The main idea behind our suggested methodology is based on Feature Matrices model (FM model, Shahabi and Banaei-Kashani, 2003) that uses clusters of customers' similar transaction data, which is similar to the Collaborative Filtering. However unlike Collaborative Filtering, this methodology overcomes the problems of personal information and privacy since it is not aware of the customer, exactly who they are, The methodology is compared with single trait model(vector model) such as visitor logs, while looking at the actual improvements of the recommendation when the context information is used. It is not easy to find real U-market data, so we experimented with factual data from a real department store with context information. The recommendation procedure of U-market proposed in this paper is divided into four major phases. First phase is collecting and preprocessing data for analysis of shopping patterns of customers. The traits of shopping patterns are expressed as feature matrices of N dimension. On second phase, the similar shopping patterns are grouped into clusters and the representative pattern of each cluster is derived. The distance between shopping patterns is calculated by Projected Pure Euclidean Distance (Shahabi and Banaei-Kashani, 2003). Third phase finds a representative pattern that is similar to a target customer, and at the same time, the shopping information of the customer is traced and saved dynamically. Fourth, the next store is recommended based on the physical distance between stores of representative patterns and the present location of target customer. In this research, we have evaluated the accuracy of recommendation method based on a factual data derived from a department store. There are technological difficulties of tracking on a real-time basis so we extracted purchasing related information and we added on context information on each transaction. As a result, recommendation based on FM model that applies purchasing and context information is more stable and accurate compared to that of vector model. Additionally, we could find more precise recommendation result as more shopping information is accumulated. Realistically, because of the limitation of ubiquitous environment realization, we were not able to reflect on all different kinds of context but more explicit analysis is expected to be attainable in the future after practical system is embodied.

Trust Building of Buyers who perceive Quality Risk High in Online Used Car Transactions: A Dyadic Trust Relationship (온라인 중고차 거래에서 품질위험을 높게 지각한 구매자의 신뢰형성: 구매자와 대리인 양자간 신뢰)

  • Lee, Seung-chang
    • Journal of Distribution Science
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    • v.7 no.3
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    • pp.49-69
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    • 2009
  • With the proliferation of electronic commerce, online transactions have become a norm. Its enormous potential, however, can be truly realized if consumers feel comfortable facing invisible sellers over the Internet, a virtual business channel. Trust has been identified as a key component in many e-Commerce studies. The purpose of this study is to find out which factors play a major role in building buyer trust and how the build-up trust affects buyer's purchase intention in online used car transactions. Based on the information asymmetry, TAM (Technology Acceptance Model), and the trust theory, our research model includes factors such as a buyer's propensity-to-trust, institutional characteristics (inspection and warranty policy), word-of-mouth referral, perceived size, and perceived benefits as independent variables. The model also includes trust as a mediate variable, purchase intention as a dependent variable, and perceived quality risk as a moderate variable. The research model is tested by analyzing 448 sample data gathered from used car websites. The result shows that the trust has significant effects on the online purchase intention, and institutional characteristics have been identified as one of the most significant factors for trust building in used car websites. For those who perceive quality risk high, actual purchasing behavior occurs only when they have trust on the used car websites, indicating that trust plays a vital role as a mediate variable. This study suggests that buyer trust on the used car websites is important to increase buyer's online purchase behavior.

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A Study on the Cloud Service Model of CaaS Based on the Object Identification, ePosition, with a Structured Form of Texts (문자열로 구조화된 사물식별아이디 이포지션(ePosition) 기반의 클라우드 CaaS(Contents as a Service) 서비스 모델에 관한 연구)

  • Lee, Sang-Zee;Kang, Myung-Su;Cho, Won-Hee
    • Information Systems Review
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    • v.15 no.3
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    • pp.129-139
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    • 2013
  • The Internet of Things (or IoT for short) which refers to uniquely identifiable objects and their virtual representations in an Internet-like structure is to be reality today. The amount of data on IoT is expected to increase abruptly and there are several key issues like usefulness interoperability between multiple distributes systems, services and databases. In this paper a methodology is proposed to realize a recently developed cloud service model, Contents as a Service (CaaS), which is contents delivery model referred to as 'on-demand contents'. In the proposed method, the global object identification, ePosition, comprising the structured form of two sorts of text strings with a separation symbol like # is applied to identify a specific content and registered with the content at the same server. It is easy-to-realize and effective to solve the interoperability problem systematically and logically. Some APIs for the proposed CaaS service are to be converged to provide some upgraded cloud service model such as 'CaaS supported SaaS' and 'CaaS supported PaaS'.

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Numerical Analysis of Flow Pattern by Outflow Gates with Manifold Channel (다기수로를 가진 수중 유출구에 의한 유동패턴에 관한 수치해석)

  • Kim, Nam-Hyeong;Lee, Chang-Lym;Ku, Bon-Soo;Song, Man-Soon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.1
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    • pp.43-49
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    • 2011
  • For the improvement of water quality in a harbor, several studies have been carried out on SEB (Seawater Exchange Breakwater) in recent years, but a problem has been shown whereby the water on the inside area far from the SEB cannot be easily exchanged. In order to solve the problem of the SEB, the Manifold channel, a new concept of the SEB, is introduced in this paper. By using the manifold channel, it is possible to exchange the water of the inside area for seawater from the outside. Here, to assess the outflow gates of the manifold channel governing flow behavior, a virtual manifold channel controlled the location, width and direction of outflow gates applied to the Jumunjin fishery port, where the SEB has been established. In addition, the desirable flow pattern of the port by utilizing the two layer current model is identified, and five general cases of the manifold channel are described in this paper. The model is verified by comparing with observation of the SEB model, and the results are in general agreement. From the results of the manifold channel, in the case of the Jumunjin fishery port, the small circulation of counter clockwise is necessary for the water exchange on the inside area, but it should be controlled by the outflow gates for other areas. Using the two layer current model, the desirable flow pattern of the port can be predicted, and the water exchange for the upper and lower layer can be examined. For the practical use of the manifold channel, further studies on the manifold channel will be necessary, and it may then be used broadly for the design of breakwater in the future.

Application Technology of Multi-texturing for Effective Representation of Natural Ground on the 4D System for Civil Engineering Projects (토목공사용 4D 시스템의 효율적인 자연지형 표현을 위한 멀티텍스처링 기법 적용기술 개발)

  • Kang Leen-Seok;Kwak Joong-Min;Jee Sang-Bok;Kim Chang-Hak;Lee Yong-Su
    • Proceedings of the Korean Institute Of Construction Engineering and Management
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    • 2004.11a
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    • pp.349-352
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    • 2004
  • 4D system has applied to construction project as a management tool after the late 1990's. Various 4D systems have been developed, however they have some problems that should be improved. Especially, the 4D system for civil engineering project needs synthesized 3D model between natural ground condition and physical facility type. It is a different problem comparing with the system for building project. 1'his study suggests an automatically synthesizing methodology between ground triangulate network and design triangulate network. Furthermore the study develops an application methodology of multi-texturing technique defined in virtual reality modeling language (VRML) for skipping the 3D model synthesizing process from the 4D model development processes. The suggested methodology is applied to the prototype of real 4D system. The proposed technique for 3D modeling may be used as an essential methodology for developing 4D system for civil engineering projects.

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Effects on the Jeju Island of Tsunamis Caused by Triple Interlocked Tokai, Tonankai, Nankai Earthquakes in Pacific Coast of Japan (일본 태평양 연안의 Tokai, Tonankai 및 Nankai의 3연동지진에 의한 지진해일이 제주도 연안에 미치는 영향)

  • Lee, Kwang-Ho;Kim, Min-Ji;Kawasaki, Koji;Cho, Sung;Kim, Do-Sam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.24 no.4
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    • pp.295-304
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    • 2012
  • This study proposed a two-dimensional horizontal numerical model based on the nonlinear shallow water wave equations to simulate tsunami propagation and coastal inundation. We numerically investigated the possible impacts of tsunami caused by the triple interlocked Tokai, Tonankai and Nankai Earthquakes on the Jeju coastal areas, using the proposed model. The simultaneous Tokai, Tonankai and Nankai Earthquakes were created a virtual tsunami model of an M9.0 earthquake. In numerical analysis, a grid nesting method for the local grid refinement in shallow coastal regions was employed to sufficiently reproduce the shoaling effects. The numerical model was carefully validated through comparisons with the data collected during the tsunami events by 2011 East Japan Earthquake and 1983 central East Sea Earthquake (Nihonkai Chubu Earthquake). Tsunami propagation triggered by the combined Tokai, Tonanakai and Nankai, Earthquakes was simulated for 10 hours to sufficiently consider the effects of tsunami in the coastal areas of Jeju Island. The numerical results revealed that water level fluctuation in tsunami propagation is greatly influenced by water-depth change, refraction, diffraction and reflection. In addition, the maximum tsunami height numerically estimated in the coastal areas of Jeju Island was about 1.6 m at Sagye port.

Application of SWAT Model considering Spatial Distribution of Rainfall (강우의 공간분포를 고려한 SWAT 모형의 적용)

  • JANG, Daewon;KIM, Duckgil;KIM, Yonsoo;Choi, Wooil
    • Journal of Wetlands Research
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    • v.20 no.1
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    • pp.94-104
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    • 2018
  • In general, the rainfall-runoff simulation is performed using rainfall data from meteorological and observational rain gauge stations. However, if we only use rainfall data from meteorological and observational rain gauge stations for runoff simulation of a large watershed, the problem in the reliability of the simulated runoff can be occurred. Therefore, this study examined the influence of the rainfall data on the simulated runoff volume by a Semi-distributed model. For this, we used rainfall data from meteorological stations, meteorological and observational stations, and a spatially distributed rainfall data from hypothetical stations obtained by kriging method. And, we estimated the areal rainfall of each sub-basin. Also the estimated areal rainfall and the observed rainfall were compared and we compared the simulated runoff volumes using SWAT model by the rainfall data from meteorological and observational rain gauge stations and runoff volume from the estimated areal rainfall by Kriging method were analyzed. This study was performed to examine the accuracy of calculated runoff volume by spatially distributed areal rainfall. The analysis result of this study showed that runoff volume using areal rainfall is similar to observed runoff volume than runoff volume using the rainfall data of weather and rain gauging station. this means that spatially distributed rainfall reflect the real rainfall pattern.

Establishment and Application of Flood Forecasting System for Waterfront Belt in Nakdong River Basin for the Prediction of Lowland Inundation of River. (하천구역내 저지대 침수예측을 위한 낙동강 친수지구 홍수예측체계 구축 및 적용)

  • Kim, Taehyung;Kwak, Jaewon;Lee, Jonghyun;Kim, Keuksoo;Choi, Kyuhyun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.294-294
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    • 2019
  • The system for predicting flood of river at Flood Control Office is made up of a rainfall-runoff model and FLDWAV model. This system is mainly operating to predict the excess of the flood watch or warning level at flood forecast points. As the demand for information of the management and operation of riverside, which is being used as a waterfront area such as parks, camping sites, and bike paths, high-level forecasts of watch and warning at certain points are required as well as production of lowland flood forecast information that is used as a waterfront within the river. In this study, a technology to produce flood forecast information in lowland areas of the river used as a waterfront was developed. Based on the results of the 1D hydraulic analysis, a model for performing spatial operations based on high resolution grid was constructed. A model was constructed for Andong district, and the inundation conditions and level were analyzed through a virtual outflow scenarios of Andong and Imha Dam.

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A Study on the intentions of early users of metaverse platforms using the Technology Acceptance Model (기술수용모델을 활용한 메타버스 플랫폼 초기 이용자들의 이용 의도에 관한 연구)

  • Park, Sunkyung;Kang, Yoon Ji
    • Journal of Digital Convergence
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    • v.19 no.10
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    • pp.275-285
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    • 2021
  • The purpose of this study is to empirically identify the process of technology acceptance of the metaverse, a virtual world-based platform that has attracted attention due to the 4th industrial revolution and the COVID-19 pandemic. The technology acceptance model (TAM) was used to identify factors affecting the use of the metaverse platforms and to analyze the causal relationship among these factors. For research, a survey was conducted on ordinary adult men and women and was analyzed using a structural equation model. The study found that perceived pleasure, interactivity, self-efficacy, and social influence had a positive effect on perceived ease-of-use. Interactivity and social influence had a statistically significant effect on perceived usefulness. The relationship between perceived ease-of-use and perceived usefulness was not statistically significant, but both perceived ease-of-use and perceived usefulness had a significant effect on positively forming attitudes toward metaverse. Lastly, favorable attitudes toward the metaverse platform had a positive effect on the intention to continue using it. Through this study, it was possible to identify the factors affecting the intention to use the metaverse and to confirm the causal relationship between the factors. A deeper understanding of users may be obtained in future if the research subject can be expanded and investigated with various factors.