• Structural Engineering and Mechanics
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• 제76권2호
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• pp.269-278
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• 2020

In this paper, the mechanical characteristics of the open type hyperbolic-parabolic membrane structure under wind load were investigated. First, the numerical simulation of a typical plane membrane structure was performed based on the Large-Eddy Simulation method. The accuracy of the simulation method was validated by the corresponding wind tunnel test results. Then, the wind load shape coefficients of open type hyperbolic-parabolic membrane structures are obtained from the series of numerical calculations and compared with the recommended values in the "Technical Specification for Membrane Structures (CECS 158: 2015). Finally, the influences of the wind directions and wind speeds on the mean wind pressure distribution of open type hyperbolic-parabolic membrane structures were investigated. This study aims to gain a better understanding of the wind-induced response for this type of structure and be useful to engineers and researchers.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
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• pp.199-202
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• 2006

• Journal of the Korean Data and Information Science Society
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• 제21권1호
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• pp.185-194
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• 2010

In recommender systems which are used widely at e-commerce, collaborative filtering needs the information of user-ratings and neighbor user-ratings. These are an important value for recommendation in recommender systems. We investigate the in-formation of rating in NBCFA (neighbor Based Collaborative Filtering Algorithm), we suggest new algorithm that improve prediction accuracy of recommender system. After we analyze relations between two variable and Error Value (EV), we suggest new algorithm and apply it to fitted line. This fitted line uses Least Squares Method (LSM) in Exploratory Data Analysis (EDA). To compute the prediction value of new algorithm, the fitted line is applied to experimental data with fitted function. In order to confirm prediction accuracy of new algorithm, we applied new algorithm to increased sparsity data and total data. As a result of study, the prediction accuracy of recommender system in the new algorithm was more improved than current algorithm.

• 지능정보연구
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• 제5권1호
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• pp.65-80
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• 1999

선박설계는 그 과정이 매우 복잡하고 많은 양의 데이터를 다루고 있는 작업으로서 그 환경이 분산화, 이질화 됨에따라 최근들어 CSCW(Computer Supported Collaborative Work)의 요구가 증대되고 있다. 본 논문에서는 분산된 선박설계 환경에서의 협동작업을 지원하기 위한 에이전트 기반 선박설계 시스템을 개발하였다. 특히 여기서는 설계 에이전트간의 정보교환 및 지식공유를 통한 선박설계의 의사결정 과정에서 발생하는 의사충돌 문제를 해결하기 위하여 사례기반 추론 기법을 이용하여 이의 해결을 시도하였다. 설계 에이전트, 이들을 중재하는 퍼실리테이터, 충돌 처리기, 그리고 사례기반 시스템의 유기적인 도움을 받아 설계자는 설계과정에서 발생하는 설계 시스템간의 의사충돌 문제에 대한 의사결정을 과거의 유사한 문제해결 사례로부터 효과적으로 처리할 수 있다.

• Journal of Astronomy and Space Sciences
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• 제19권2호
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• pp.107-122
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• 2002

Multi-body spacecraft attitude and configuration control formulations based on the use of collaborative control theory are considered. The control formulations are based on two-player, nonzero-sum, differential game theory applied using a Nash strategy. It is desired that the control laws allow different components of the multi-body system to perform different tasks. For example, it may be desired that one body points toward a fixed star while another body in the system slews to track another satellite. Although similar to the linear quadratic regulator formulation, the collaborative control formulation contains a number of additional design parameters because the problem is formulated as two control problems coupled together. The use of the freedom of the partitioning of the total problem into two coupled control problems and the selection of the elements of the cross-coupling matrices are specific problems ad-dressed in this paper. Examples are used to show that significant improvement in performance, as measured by realistic criteria, of collaborative control over conventional linear quadratic regulator control can be achieved by using proposed design guidelines.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.364-367
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• 2000

As computer system and information/communication technology develop rapidly, nowadays CSCW(Computer Supported Collaborative Work) system appears, through which it is available to work on virtual space without any restriction of time and place. Most of Un systems depend on a special network and groupware. The systems of graphics and CAD are not so many because they are characterized by Hardware and application software. In this paper, we propose a web-based collaborative CAD system which can be jointly worked on Internet WWW being independent from any platforms. It can generate and handle objects easily using lava 3D, and it can transmit, print, and store them. The interactive work for designing objects can be also carried out through dialling with each other. This system is executed in the environment of Client/server. Clients connect to the server through lava applet on WWW. The server is implemented by lava application, and it consists of three components : connection manager which controls the contact to users, work manager which keeps viewing in concurrency and provides virtual work space sharing with others, and solid modeler which generates 3D object.

• Nuclear Engineering and Technology
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• 제52권3호
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• pp.581-588
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• 2020

The membrane fouling is an important problem for FO applied to the radioactive wastewater treatment. The FO fouling characteristics for simulated radioactive wastewater treatment was investigated. On-line cleaning by deionized (DI) water and external cleaning by ultrasound and HCl were applied for the fouled membrane. The effectiveness and foulant removing amount by each-step cleaning were evaluated. The membrane fouling was divided into three stages. Co(II), Sr(II), Cs(I), Na(I) were all found deposited on both active and support layers of the membrane surface, resulting in membrane surface became rougher and more hydrophobic, which increased membrane resistance. On-line cleaning by DI water recovered the water flux to 69%. HCl removed more foulants than ultrasound.

• Journal of Computing Science and Engineering
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• 제11권3호
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• pp.100-108
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• 2017

In the field of Internet of Things (IoT), smarter embedded devices offer functions via web services. The Quality-of-Service (QoS) prediction is a key measure that guarantees successful IoT service applications. In this study, a collaborative filtering method is presented for predicting response time of IoT service due to time-awareness characteristics of IoT. First, a calculation method of service response time similarity between different users is proposed. Then, to improve prediction accuracy, initial similarity values are adjusted and similar neighbors are selected by a similarity threshold. Finally, via a densified user-item matrix, service response time is predicted by collaborative filtering for current active users. The presented method is validated by experiments on a real web service QoS dataset. Experimental results indicate that better prediction accuracy can be achieved with the presented method.

• 한국멀티미디어학회논문지
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• 제20권2호
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• pp.336-343
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• 2017

We propose a real time personalized recommendation algorithm on the mobile device. We use a unified collaborative filtering with reduced data. We use Fuzzy C-means clustering to obtain the reduced data and Konohen SOM is applied to get initial values of the cluster centers. The proposed algorithm overcomes data sparsity since it extends data to the similar users and similar items. Also, it enables real time service on the mobile device since it reduces computing time by data clustering. Applying the suggested algorithm to the MovieLens data, we show that the suggested algorithm has reasonable performance in comparison with collaborative filtering. We developed Android-based smart-phone application, which recommends restaurants with coupons and restaurant information.

• Management Science and Financial Engineering
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• 제11권3호
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• pp.137-153
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• 2005

Collaborative filtering-based recommendation systems make personalized recommendations based on users' ratings on products. Recommender systems must collect sufficient rating information from users to provide relevant recommendations because less user rating information results in poorer performance of recommender systems. To learn about new users, recommendation systems must first present users with an initial item list. In this study, we designed and analyzed seven selection strategies including the popularity, favorite, clustering, genre, and entropy methods. We investigated how these strategies performed using MovieLens, a public dataset. While the favorite and popularity methods tended to produce the highest average score and greatest average number of ratings, respectively, a hybrid of both favorite and popularity methods or a hybrid of demographic, favorite, and popularity methods also performed within acceptable ranges for both rating scores and numbers of ratings.