• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.246-251
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• 1998

The basic requirement of a distributed multimedia system are intramedia synchronization which asks the strict delay and jitter for the check period of media buffer and the scaling duration with periodic continuous media such as audio and video media, and intermedia synchronization that needs the constraint for relative time relations among them when several media are presented in parallel. In this paper, a distributed multimedia synchronization algorithm based on the fuzzy logic is presented and the performance is evaluated through simulation. Intramedia synchronisation algorithm uses the media scaling techniques and intermedia synchronization algorithm uses variable service rates on the basis of fuzzy logic to solve the multimedia synchronization problem.

• Journal of the Korea Society of Computer and Information
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• v.17 no.4
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• pp.75-82
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• 2012

The Photoplethysmogram is a similar periodic signal that synchronized to a heartbeat. In this paper, we propose a periodic moving average filter that use similarity of Photoplethysmogram. This filtering method has the average value of each samples through separating the cycle of PPG signal. If there are some motion artifacts in continuous PPG signal, disjoin the signal based on cycle. And then, we made these signals to have same cycle by coordinating the number of sample. After arrange these cycles in 2 dimension, we put the average value of each samples from starting till now. So, we can eliminate the motion artifacts without damaged PPG signal.

• The KIPS Transactions:PartA
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• v.11A no.7 s.91
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• pp.547-554
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• 2004

To play back CM (Continuous Media) in online mode, the multimedia system Is required to have a real-time disk scheduling scheme that can efficiently fulfill the strict temporal constraints of serviced CM streams to prevent hiccups. In general, such disk scheduling is performed based on the concept of periodic prefetching since a CM stream has a rather long Playback time. In this paper, we also propose a periodic prefetching scheme that runs by using real-time disk channels, called on-time delivery channels. Since the channels are generated from the bulk-SCAN algorithm and they can be allocated in a very flexible manner based on the EDF (earliest-deadline-first) algorithm, the proposed scheme provides a better Performance in terms of I/O throughput and the average response time, as well as hiccup-free playback of concurrent CM streams. To show that the proposed scheme outperforms other methods, we give some simulation results.

• Journal of Korea Multimedia Society
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• v.1 no.1
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• pp.18-25
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• 1998

The basic requirements of distributed multimedia systems are intramedia synchronization which asks the strict delay and jitter for the check period of media buffer and the scaling duration with periodic continuous media such as audio and video media, and intermedia synchronization that needs the constraint for relative time relations among them when several media are presented in parallel. In this paper, a distributed intermedia synchronization algorithm that solves the intermedia synchronization problem by using variable service rates based on the fuzzy logic is designed and then the performance is evaluated through simulation.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.388-394
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• 2014

In this paper, we propose a three-dimensional (3D) image correlator by use of computational integral imaging reconstruction based on the modified convolution property of periodic functions (CPPF) for recognition of partially occluded objects. In the proposed correlator, elemental images of the reference and target objects are picked up by a lenslet array, and subsequently are transformed to a sub-image array which contains different perspectives according to the viewing direction. The modified version of the CPPF is applied to the sub-images. This enables us to produce the plane sub-image arrays without the magnification and superimposition processes used in the conventional methods. With the modified CPPF and the sub-image arrays, we reconstruct the reference and target plane sub-image arrays according to the reconstruction plane. 3D object recognition is performed through cross-correlations between the reference and the target plane sub-image arrays. To show the feasibility of the proposed method, some preliminary experiments on the target objects are carried out and the results are presented. Experimental results reveal that the use of plane sub-image arrays enables us to improve the correlation performance, compared to the conventional method using the computational integral imaging reconstruction algorithm.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.217-230
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• 2019

In this study, a fatigue damage estimation for an ice-going vessel navigating through broken ice fields was carried out. A numerical model to simulate the interaction between ice and structure developed using the finite element method was introduced. Time series of stresses calculated by the proposed model and the corresponding fatigue analysis results are presented. The numerical model enables the long time analysis through an efficient interaction model, the application of the periodic media analysis and the convolution integral, and it allows the stress time history to be extracted directly using the finite element method. To describe the probability distribution of stress amplitudes, the 2-parameter Weibull model was applied to the calculated stress time history, and the fatigue damage was calculated using the Palmgren-Miner rule. Finally, the fatigue damage considering the ice conditions of the Baltic Sea was calculated using the proposed method and LR method, and the results were compared to each other.

• The Journal of the Korea Contents Association
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• v.16 no.11
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• pp.83-90
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• 2016

In this paper, we performed the analysis of transmission performance for Collision Free Period(CFP) supported by the low-power communication technology, IEEE 802.15.4 MAC (Media Access Control). For the analysis, periodic traffic, original service target of CFP, is considered and, according to the Quality of Service required, packet arrival pattern to MAC layer is categorized as batch and non-batch, and analysis on throughput, delay, and energy is performed for those patterns. On the basis of the obtained analysis, performance comparison with Collision Avoidance Period(CAP) is carried out for the health care applications that generate periodic traffic such as Pedometer, ECG, EMG. The evaluation confirms that CFP is more energy efficient for healthcare applications that generate periodic and time-critical traffic and moreover for the application with high bandwidth requirement CFP achieves up to 46% energy savings compared to CAP.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.197-202
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• 2007

Formaldehyde is a typical indoor air pollutant that has numerous adverse health problems in modern living conditions. Phytoremediation that use plants to remove contaminants from polluted media can be applied to improve indoor air quality. Two sets of experiments; 1) two rooms in newly built auditorium and 2) a bed room in 2-year-old apartment; were performed to investigate plant effects on indoor formaldehyde concentration. It was observed from the experiments that plant can help decontaminating formaldehyde at low concentration level (0.1 ppm) but the effects decreased considerably at hish concentration (1ppm). The purification effects of indoor plant also showed the periodic pattern due to its physiological activity. More purification was observed as increasing plant density in the bed room but the formaldehyde concentration returned the original concentration level in two days after removing plants. It was suggested from the results that air purification using plants is an effective means of reduction on indoor formaldehyde level, though, reduction of source is highly desirable when the concentration level is high. The results also suggest that introducing supplementary purifying aids and/or efficient ventilation could be considered due to periodic removal pattern of plant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.919-940
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• 2012

Video on Demand (VOD) is a multimedia service which allows a remote user to select and then view video at his convenience at any time he wants, which makes the VOD become an important technology for many applications. Numerous periodic VOD broadcasting protocols have been proposed to support a large number of receivers. Broadcasting is an efficient transmission scheme to provide on-demand service for very popular movies. This paper proposes a new broadcasting scheme called Popularity Cushion Staggered Broadcasting (PCSB). The proposed scheme improves the Periodic Broadcasting (PB) protocols in the latest mobile VOD system, which is called MobiVoD system. It also, reduces the maximum waiting time of the mobile node, by partitioning the $1^{st}$ segment of the whole video and storing it in the Local Media Forwarder (LMF) exactly in the Pool of RAM (PoR), and then transmitting them when the mobile nodes miss the $1^{st}$ broadcasted segment. The results show that the PCSB is more efficient and better than the all types of broadcasting and caching techniques in the MobiVoD system. Furthermore, these results exhibits that system performance is stable under high dynamics of the system and the viewer's waiting time are less than the previous system.

• Korea-Australia Rheology Journal
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• v.21 no.1
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• pp.71-79
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• 2009

The incomplete saturation and the void formation during the resin infiltration into fibrous porous media in the resin transfer molding process cause failure in the final product during its service. In order to better understand flow behavior during the filling process, a finite-element scheme for transient flow simulation across the micro-structured fibrous media is developed in the present work. A volume-of- fluid (VOF) method has been incorporated in the Eulerian frame to capture the evolution of flow front and the vertical periodic boundary condition has been combined to avoid unwanted wall effect. In the microscale simulation, we investigated the transient filling process in various fiber structures and discussed the mechanism leading to the flow fingering in the case of random fiber distribution. Effects of the filling pressure, the shear-thinning behavior of fluid and the volume fraction on the flow front have been investigated for both intra-tow and the inter-tow flows in dual-scale fiber tow models.