• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3237-3256
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• 2012

In the context of effective usage of a scarce spectrum resource, emerging wireless communication standards will demand spectrum sharing with existing systems as well as multiple access with higher spectral efficiency. We mathematically analyze the sum throughput of a spectrum sharing space-division multiple access (SDMA) system, which forms a transmit null in the direction of other coexisting systems while satisfying orthogonal beamforming constraints. For a large number of users N, the SDMA throughput scales as log N at high signal-to-noise ratio (SNR) ((J-1) loglog N at normal SNR), where J is the number of transmit antennas. This indicates that multiplexing gain of the spectrum sharing SDMA is $\frac{J-1}{J}$ times less than that of the non-spectrum sharing SDMA only using orthogonal beamforming, whereas no loss in multiuser diversity gain. Although the spectrum sharing SDMA always has lower throughput compared to the non-spectrum sharing SDMA in the non-coexistence scenario, it offers an intriguing opportunity to reuse spectrum already allocated to other coexisting systems.

• Journal of Information Science Theory and Practice
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• v.4 no.3
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• pp.57-70
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• 2016

Purpose The purpose of the study is to identify the need of a mobile based library information and service delivery system in developing countries, identify the services that are possible to provide with the help of mobile phones and their applications, design a mobile based library information and service delivery system, and identify major challenges regarding mobile based library information and service delivery systems.Design/ Methodology/ Approach The research is exploratory in nature. This paper is based on a review of literature, survey information, and on the author’s own viewpoints. A comprehensive search of scientific literature has been done along with a survey for validating the necessity of designing mobile based library information and service delivery systems. Responses to closed-ended questions in particular on 7-point Likert scales were analyzed using the descriptive analysis techniques of SPSS 20.0 and responses to other closed-ended questions were analyzed using general statistics.Findings The research indicates that users of academic libraries, especially students and faculty members, have a positive notion regarding designing and implementing a mobile based library information and service delivery system. It also reveals user opinions regarding the possible problems associated with the design and implementation of a mobile based library information and service delivery system.Originality The paper explores mobile based library information and service delivery systems for better and faster service provision to its potential users.

• Asia pacific journal of information systems
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• v.12 no.2
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• pp.25-44
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• 2002

The internet-based electronic commerce is considered as a new strategic alternative to boost competitiveness for small and medium-sized enterprises(SMEs). However, very little research about them has been reported. Meanwhile, the cyber shopping shops in Korea are growing rapidly in their numbers, scales, and diversity of business models. The primary purpose of this study is to investigate the factors influencing outsourcing decisions in the implementation of small and medium-sized cyber shopping shops. Based on the previous studies on IS outsourcing, marketing channel, and their related theories, three areas of determinants(IT & organizational, product, marketing channel characteristics) were identified. Responses of 125 cyber shopping shops from e-mail survey indicate that IT capability, technical specificity of shop implementation, degree of product customization, average amount of order, marketing capability are negatively associated with outsourcing of cyber shopping shop implementation. The results also indicate that the outsourcing decision on systems implementation and marketing channel selection(direct/indirect selling) is performed separately.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.779-781
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• 2007

Nowadays, as the increasing functionality and scales of embedded systems, system design grows more complex than before. So verification and simulation of systems become an important facet in hardware-software co-design issues. But it is almost impossible to simulate an embedded system without real hardware implementation or environment communication, especially for control-dominated reactive systems. Therefore, in this paper, we will introduce a GUI environment module generator for integrated Esterel\C++ simulation. By generating the GUI modeling environment, we can simulate and verify the whole embedded system conveniently.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.9
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• pp.2361-2376
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• 2023

The electrocardiogram (ECG) signal is commonly used to screen and diagnose cardiovascular diseases. In recent years, deep neural networks have been regarded as an effective way for automatic ECG disease diagnosis. The convolutional neural network is widely used for ECG signal extraction because it can obtain different levels of information. However, most previous studies adopt single scale convolution filters to extract ECG signal features, ignoring the complementarity between ECG signal features of different scales. In the paper, we propose a dual-scale network with convolution filters of different sizes for 12-lead ECG classification. Our model can extract and fuse ECG signal features of different scales. In addition, different spatial and time periods of the feature map obtained from the 12-lead ECG may have different contributions to ECG classification. Therefore, we add a spatial-temporal attention to each scale sub-network to emphasize the representative local spatial and temporal features. Our approach is evaluated on PTB-XL dataset and achieves 0.9307, 0.8152, and 89.11 on macro-averaged ROC-AUC score, a maximum F1 score, and mean accuracy, respectively. The experiment results have proven that our approach outperforms the baselines.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.20-27
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• 1987

The hierarchical approach method is proposed to sperate each different time scale sub-systems from linear time invariant multi-parameter singular perturbation systems. By means of this proposal, the original multi-parameter singular perturbation systems is completely separated into independent subsystems with each different time scale. It is also investigated that the controllability of the system is invariant. And this paper applies singular perturbation methods to the minimum control effort problem for linear time invariant systems with constrained controls. Also near-optimum control theory, which is based on dividing the total time interval with the time scales respectively, is proposed. As a result, the time scale separation method is show to be particularly useful in a near optimum design which can be otained through a decentralized control structure.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4242-4268
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• 2014

The Cyber-Physical System (CPS) is a term describing a broad range of complex, multi-disciplinary, physically-aware next generation engineered system that integrates embedded computing technologies (cyber part) into the physical world. In order to define and understand CPS more precisely, this article presents a detailed survey of the related work, discussing the origin of CPS, the relations to other research fields, prevalent concepts, and practical applications. Further, this article enumerates an extensive set of technical challenges and uses specific applications to elaborate and provide insight into each specific concept. CPS is a very broad research area and therefore has diverse applications spanning different scales. Additionally, the next generation technologies are expected to play an important role on CPS research. All of CPS applications need to be designed considering the cutting-edge technologies, necessary system-level requirements, and overall impact on the real world.

• Journal of Korean Library and Information Science Society
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• v.22
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• pp.245-276
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• 1995

This study analyzed the process of information service and its factors in the cognitive viewpoint. And developed a conceptual model to help in developing future information systems and services. The results of this study were summarized as follows : 1) The paradigm of information user study is changing from the system-centered to the user-centered one. 2) The researchers describe the user's internal cognitive process as the starting point of the information service. 3) The user's personal cognitive process influence the process of the information service over. And the focus is a microscopic one including the factors of the perception and recognition of the stimulus, remembering and searching information, reasoning the rules, recognition of the patterns, formalization of the concepts, etc. 4) The information librarian performs the role as a knowledge/ information system interface, and his knowledge structure reflects the organization of that knowledge/information system. 5) The information librarians can perform their role as information specialists actively and offensively. And the performance of the librarians can be measured on the scales of the su n.0, pplying capability of relevant information and the client satisfaction.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.3037-3054
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• 2019

Public bicycle system (PBS) is a new emerging and popular mode of public transportation. PBS data can be adopted to analyze human movement patterns. Previous work usually focused on specific scales, and the relationships between different levels of hierarchies are ignored. In this paper, we introduce a multi-scale and interactive visual analytics system to investigate human cycling movement and PBS usage condition. The system supports level-of-detail explorative analysis of spatio-temporal characteristics in PBS. Visual views are designed from global, regional and microcosmic scales. For the regional scale, a bicycle network is constructed to model PBS data, and an flow-based community detection algorithm is applied on the bicycle network to determine station clusters. In contrast to the previous used Louvain algorithm, our method avoids producing super-communities and generates better results. We provide two cases to demonstrate how our system can help analysts explore the overall cycling condition in the city and spatio-temporal aggregation of stations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4439-4455
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• 2021

Compared with two-stage object detection algorithms, one-stage algorithms provide a better trade-off between real-time performance and accuracy. However, these methods treat the intermediate features equally, which lacks the flexibility to emphasize meaningful information for classification and location. Besides, they ignore the interaction of contextual information from different scales, which is important for medium and small objects detection. To tackle these problems, we propose an image pyramid network based on dual attention mechanism (DAIPNet), which builds an image pyramid to enrich the spatial information while emphasizing multi-scale informative features based on dual attention mechanisms for one-stage object detection. Our framework utilizes a pre-trained backbone as standard detection network, where the designed image pyramid network (IPN) is used as auxiliary network to provide complementary information. Here, the dual attention mechanism is composed of the adaptive feature fusion module (AFFM) and the progressive attention fusion module (PAFM). AFFM is designed to automatically pay attention to the feature maps with different importance from the backbone and auxiliary network, while PAFM is utilized to adaptively learn the channel attentive information in the context transfer process. Furthermore, in the IPN, we build an image pyramid to extract scale-wise features from downsampled images of different scales, where the features are further fused at different states to enrich scale-wise information and learn more comprehensive feature representations. Experimental results are shown on MS COCO dataset. Our proposed detector with a 300 × 300 input achieves superior performance of 32.6% mAP on the MS COCO test-dev compared with state-of-the-art methods.