• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.7
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• pp.2454-2467
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• 2015

Increasing traffic and bandwidth requirements bring challenges to the next generation wireless networks (5G). As one of the main technology in 5G networks, Ultra-Dense Network (UDN) can be used to improve network coverage. In this paper, a radio over fiber based model is proposed to solve the load balancing problem in ultra-dense network. Stochastic differential game is introduced for the load balancing algorithm, and optimal load allocated to each access point (RAP) are formulated as Nash Equilibrium. It is proved that the optimal load can be achieved and the stochastic differential game based scheme is applicable and acceptable. Numerical results are given to prove the effectiveness of the optimal algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2476-2495
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• 2021

Model-based software architecture verification and test scenarios generation are becoming more and more important in the software industry. Based on the existing temporal graph grammar, this paper proposes a new formalization method of the context-sensitive graph grammar for aiming at UML activity diagrams, which is called the UML Activity Graph Grammar, or UAGG. In the UAGG, there are new definitions and parsing algorithms. The proposed mechanisms are able to not only check the structural correctness of the UML activity diagram but also automatically generate the test scenario according to user constraints. Finally, a case study is discussed to illustrate how the UAGG and its algorithms work.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.386-388
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• 2003

We are developing a web-based movie recommender system that catches and reasons with user profiles and ratings to recommend movies. In the paper, we outline the current status of our implementation with particular emphasis on the mechanisms used to provide effective recommendations. Social recommender systems collect ratings of items from many individuals and use nearest-neighbor techniques to make recommendations to a user. However, these methods only depend on the ratings and ignore other useful information. Our primary concern is to provide an approach that can recommend the movies based on not only the user ratings but also the significant amount of other information that is available about the nature of each items - such as cast list or movie genre. We experimentally evaluate our approach and compare them to conventional social filtering, which suggests merits to our approach.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.19-21
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• 2002

Writing requirements in formal notation for a safety-critical system can improve software quality and reduce the errors that may arise later on in the software development life cycle. In this paper, we propose a formal specification approach used to describe the nuclear control system. The approach is based on the existing AECL approach that was the only formal specification technique applied to nuclear control systems in the past. Although the approach is AECL-based, the complex descriptions of certain requirements have been reduced by using different specification techniques. We discuss the differences and how the proposed approach provides not only specification but also verification environment.

• ETRI Journal
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• v.35 no.2
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• pp.336-339
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• 2013

To enhance the symbol error rate (SER) performance of the two-way relay channels with physical layer network coding, this letter proposes a relay selection scheme, in which the relay with the maximal minimum distance between different points in its constellation among all relays is selected to assist two-way transmissions. We give the closed-form expression of minimum distance for binary phase-shift keying and quadrature phase-shift keying. Additionally, we design a low-complexity method for higher-order modulations based on look-up tables. Simulation results show that the proposed scheme improves the SER performance for two-way relay networks.

• Journal of Information Processing Systems
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• v.14 no.1
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• pp.218-227
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• 2018

Vocal effort detection is important for both robust speech recognition and speaker recognition. In this paper, the spectral information entropy feature which contains more salient information regarding the vocal effort level is firstly proposed. Then, the model fusion method based on complementary model is presented to recognize vocal effort level. Experiments are conducted on isolated words test set, and the results show the spectral information entropy has the best performance among the three kinds of features. Meanwhile, the recognition accuracy of all vocal effort levels reaches 81.6%. Thus, potential of the proposed method is demonstrated.

• Journal of Information Processing Systems
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• v.13 no.6
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• pp.1467-1486
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• 2017

Fuzzy co-clustering is sensitive to noise data. To overcome this noise sensitivity defect, possibilistic clustering relaxes the constraints in FCM-type fuzzy (co-)clustering. In this paper, we introduce a new possibilistic fuzzy co-clustering algorithm based on information bottleneck (ibPFCC). This algorithm combines fuzzy co-clustering and possibilistic clustering, and formulates an objective function which includes a distance function that employs information bottleneck theory to measure the distance between feature data point and feature cluster centroid. Many experiments were conducted on three datasets and one artificial dataset. Experimental results show that ibPFCC is better than such prominent fuzzy (co-)clustering algorithms as FCM, FCCM, RFCC and FCCI, in terms of accuracy and robustness.

• Journal of Information Processing Systems
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• v.15 no.1
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• pp.91-99
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• 2019

An innovative tone modeling framework based on deep neural networks in tone recognition was proposed in this paper. In the framework, both the prosodic features and the articulatory features were firstly extracted as the raw input data. Then, a 5-layer-deep deep belief network was presented to obtain high-level tone features. Finally, support vector machine was trained to recognize tones. The 863-data corpus had been applied in experiments, and the results show that the proposed method helped improve the recognition accuracy significantly for all tone patterns. Meanwhile, the average tone recognition rate reached 83.03%, which is 8.61% higher than that of the original method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1997.06a
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• pp.89-94
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• 1997

In this paper, we present a VR-based interface method which provides users more natural, realistic, and interactive communication and collaboration tool. Since most services in the communication systems matches with the services in the real world, the best understanding would be achieved when the communication services are represented in accordance with the services in the real world. However, conventional text-based interface and 2D GUI cannot provide such reality to the users. In this paper, we discuss VR-based interface to overcome such difficulty and introduce one instance of communication system using the VR-based realistic, what we call Virtual Village, which we are currently developing. This application might be applied to education in virtual space, desktop conferencing system, and entertainment such as MUD or the games in the distributed environment, etc.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.91-92
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• 2023

근로자의 수를 최소화한 자동화 공장의 경우 전체 공장의 상태를 실시간으로 정확하게 확인하기 어려운 문제가 있다. 또한, 장비나 센서의 배치가 복잡하고 명칭만으로 이해하기 어려워 현장에 있지 않은 사람들은 해당 데이터의 의미나 문제 발생 여부를 판단하기 어렵다. 이 논문은 시·공간적 한계를 극복하고 공장의 상태를 한눈에 파악할 수 있는 실시간 공장 상태 정보 시각화 도구를 구현하여 상시적인 모니터링과 함께 이상 상태 발생 시 빠른 대처가 가능하도록 하였다. 이 도구는 반응형 웹 기반으로 개발하여 모바일 환경에서도 동일하게 작동하기 때문에 범용성 있는 스마트 팩토리 구축 시스템의 일부로 활용할 수 있다.