• Journal of Korea Multimedia Society
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• v.15 no.4
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• pp.516-525
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• 2012

In this paper, an efficient technique for enhancing the QoS of multimedia service for an WiMedia network applying distributed cooperative medium access (D-MAC) protocol is proposed. D-MAC protocol has been proposed to support high-rate Wireless Personal Area Networks (HR-WPANs) by the WiMedia Alliance. Unlike the centralized IEEE 802.15.3 MAC, the D-MAC UWB specified by WiMedia supports all devices to be self-organized and removes the SOP (Simultaneous Operating Piconet) problem, i.e., packet collisions between overlapped piconets in the centralized IEEE 802.15.3 MAC. However the WiMedia D-MAC can't prevent reduce the throughput degradation occurred by mobile nodes with low data rate. Therefore, a distributed cooperative MAC protocol for multi-hop UWB network is proposed in this paper. The proposed technique can intelligently select the transmission path with higher data rate to provide real-time multimedia services with minimum delay, thus enhances QoS of multimedia service.

• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.647-654
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• 2003

The replication of data is used to increase its availability and to improve the performance of a system. The distributed database system has to maintain both the database consistency and the replica consistency. This paper proposes an algorithm which resolves the conflict of the operations by using the mechanism based on the structure that the replicas of each data item are hierarchically organized. Each update is propagated along the tree based on the fact that the root of each data item is the primary replica in partially replicated databases. The use of a hierarchy of data may eliminate useless propagation since the propagation can be done only to sites having the replicas. In consequence, the propagation delay of updates may be reduced. By using the timestamp and a compensating transaction, our algorithm resolves the non-serializability problem caused by the conflict of operations that can happen on the way of the update propagation due to the lazy propagation. This resolution also guarantees the data consistency.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.10
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• pp.327-330
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• 2016

In the road environment with lots of vehicles, we can increase the number of vehicles on the road (i.e., road capacity) and enhance the comfortability of drivers if vehicles are organized into platoons. In the traditional vehicle platooning mechanisms, a pre-determined set of vehicles are allowed to form a platoon and, among them, a specific vehicle is designated as the platoon leader. In this type of platoon mechanisms, platoon is limited in improving the road capacity because the vehicles allowed to involve into platooning are restricted. Therefore, in this paper, we propose an adaptive platoon formation mechanism that allows any vehicle to be a platoon leader from which a platoon is formed. In the proposed mechanism, a platoon leader is elected based on the relative velocity and location information of neighboring vehicles obtained through the periodic exchange of beacon messages among vehicles. Through the NS-3 based simulations, we show the performance of our proposed mechanism in terms of road capacity improvement.

• KIISE Transactions on Computing Practices
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• v.20 no.12
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• pp.670-675
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• 2014

Graphical user interfaces (GUI) in modern software deliver information visually, and a well-designed interface can provide information to the use in an organized and intuitive manner while poorly-designed interfaces can cause visual inconvenience and confusion. In order to effectively deliver information to the user, visual attention should be placed on a prominent location in the image. This paper introduces a method based on a human visual system (HVS) that can improve Metro-style GUIs by reducing a user's workload to visually find information. Our method is designed with spatial mapping and color mapping for buttons in the Metro-style GUI. Also we define a metric for Metro-style GUI effectiveness, including an optimization algorithm. The results show that our method improves the performance of visual search tasks in a Metro-style GUI.

• Journal of KIISE:Software and Applications
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• v.36 no.2
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• pp.122-130
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• 2009

Conventional approaches for car number plate detection have dealt with those input images having similar sizes and simple background acquired under well organized environment. Thus their performance get reduced when input images include number plates with different sizes and when they are acquired under different lighting conditions. To solve these problem, this paper proposes a new scheme that uses the geometrical features of number plates and their topological information with reference to other features of the car. In the first step, those edges constructing a rectangle are detected and several pixels neighboring those edges are selected as the seed pixels for region growing. For region growing, color and intensity are used as the features, and the result regions are merged to construct the candidate for a number plate if their features are within a certain boundary. Once the candidates for the number plates are generated then their topological relations with other parts of the car such as lights are tested to finally determine the number plate region. The experimental results have shown that the proposed method can be used even for detecting small size number plates where characters are not visible.

• Journal of KIISE:Information Networking
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• v.36 no.6
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• pp.481-491
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• 2009

In this paper, we proposed a hybrid P2P overlay structure for live media streaming. The proposed structure consists of the mesh overlay organized by peers according to the geographical proximity and similar bandwidth range and the tree overlay formed by the peers for which the stability of participation is approved. The proposed scheme enhances the robustness of tree overlay and the long delay of mesh overlay by intelligently combining the utilization of the tree overlay and the mesh overlay. Furthermore, the peers with a large up-link bandwidth are located near to the media source peer. Therefore, it reduces the height of tree, and as a result, the stream transmission delay. Through simulation, we evaluated the performance of the proposed scheme in terms of scalability and quality of services.

• Journal of Information Technology Services
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• v.19 no.5
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• pp.137-153
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• 2020

Most enterprises today work on digital transformation projects to cope with uncertainties caused by the rapid change and cutting-edge technology. The key point is they need to take a novel approach on new projects for high performance. In this context, there is a growing interest in utilizing agile method; however, many studies on Impact of Digital Transformation on the Results of Innovation do not deal with agile methodology. The research specifies the case of Seoul Metro, regarded as best-practice on digital transformation, based on the agile way of working. The case study is based on in-depth interview with Seoul Metro's executives and employees, and the interview is analyzed using keywords from the 12 Agile Principles. Thus, among the 12 Agile Principles, Motivation and Trust, Face-to-face Interactions, Continuous Attention to Technical excellence and good design, Self-Organizing Team contributed the most to successful digital transformation projects. In addition, based on Requirements Uncertainty and Technical Degree of Uncertainty, they carry different kinds of traits. For instance, the higher the uncertainty toward requirements and required technology is, the more technological development pace is maintained. Given the conservative nature of public corporations, it is necessary to adopt the agile way of working, such as improving employees' technological capabilities and allowing teams to be organized within themselves, in a bid to produce successful innovation outcome.

• Journal of Sericultural and Entomological Science
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• v.51 no.2
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• pp.114-118
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• 2013

This study examines how an experimental-based learning program using singing insects improves the academic achievement of elementary school children. Study subjects were a total of 123 elementary students at their $2^{nd}$ and $3^{rd}$ grade who voluntarily participated in an experience-based learning program organized by Seodaemun Museum of Natural History, Seoul. Students were given the same survey questionnaires before and after taking the learning program, and this procedure was repeated in 7 independent replication trials. Result from a paired t-test indicated that the learning program had a positive effect on academic performance, with students gaining significantly higher mean scores in the survey test after taking the program than before. This result suggests that the experience-based learning program using singing insects is effective at improving student's academic achievement. Our study provides a critical impetus for developing a variety of other experience-based learning programs using insects like ours, leading us to anticipate that these programs will be practiced more systematically and actively in the classroom in future.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.4
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• pp.45-50
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• 2004

In this paper, we propose a new PCA-based LDA Mixture Algorithm(PLMA) for real-time face recognition system. This system greatly consists of the two parts: 1) face extraction part; 2) face recognition part. In the face extraction part we applied subtraction image, color filtering, eyes and mouth region detection, and normalization method, and in the face recognition part we used the method mixing PCA and LDA in extracted face candidate region images. The existing recognition system using only PCA showed low recognition rates, and it is hard in the recognition system using only LDA to apply LDA to the input images as it is when the number of image pixels ire small as compared with the training set. To overcome these shortcomings, we reduced dimension as we apply PCA to the normalized images, and apply LDA to the compressed images, therefore it is possible for us to do real-time recognition, and we are also capable of improving recognition rates. We have experimented using self-organized DAUface database to evaluate the performance of the proposed system. The experimental results show that the proposed method outperform PCA, LDA and ICA method within the framework of recognition accuracy.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.64-72
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• 2013

Recently, stream cipher Rabbit was selected for the final eSTREAM portfolio organized by EU ECRYPT and as one of algorithm in part of ISO/IEC 18033-4 Stream Ciphers on ISO Security Standardization. However, a feasibility of practical power analysis attack to algorithm in experiment was introduced. Therefore, we propose appropriate methods such as random masking and hiding schemes to secure against power analysis attack on stream cipher Rabbit. We implement the proposed method with increment of 24% operating time and 12.3% memory requirements due to maintaining a high-speed performance. We use a 8-bit RISC AVR microprocessor (ATmegal128L chip) to implement our method for practical experiments, and verify that stream cipher Rabbit with our method is secure against power analysis attack.