• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.3
• /
• pp.48-54
• /
• 2012

The quality of real-time voice communication over Internet Protocol networks based on telematics is affected by network impairments such as delays, jitters, and packet loss. To resolve this issue, this paper proposes a receiver-based enhancing method of VoIP speech quality. The proposed method enables users to deliver high-quality voice using playout control and signal reconstruction, which consists of concealment of lost packets, adaptive playout-buffer scheduling using active jitter estimation, and smooth interpolation between two signals in a transition region. The proposed algorithm achieves higher Perceptual Evaluation of Speech Quality (PESQ) values and low buffering delay than the reference algorithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.5
• /
• pp.65-71
• /
• 2011

Face warping techniques have been used for correcting image distortion as well as for creative purposes(e.g., morphing). Smartphone can capture an image from camera and transfer it through network. Thus, warping software which is implemented on the smartphone may be widely used in the fields of game and plastic surgery. This paper describes the design of face warping software using transformation with multiple pairs of lines and bilinear interpolation, and then shows the implementation results on the smartphone. Through many people review, this software showed real-time responsiveness and good transformation quality.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.2
• /
• pp.391-396
• /
• 2018

A variety of experiments are being conducted with the advent of Learning Model for flipped-learning. In order to apply flipped-learning as a method of teaching, most of them require a pre-prepared learning video. In this case, there is the burden to create the samples of a 13 weeks, except for the mid term and the final exam in college. These systems also make it difficult to change learning content. In this paper, we suggest using blogs to improve the characteristics that existing flippling systems are less adaptable to environmental changes. A blog can be a good thing for learners who are comfortable with the Internet, In this study, we experiment with flipped-learning, which applies blog to one subject. As a result, we would like to evaluate the meaningful learning effects of this study.

• Journal of Korean Institute of Industrial Engineers
• /
• v.23 no.1
• /
• pp.23-37
• /
• 1997

In this paper, performance analysis of video traffic shaper for Motion Picture Experts Group (MPEG) video traffic in on ATM network are investigated. Traffic shaping for MPEG video traffic is proposed as a traffic control function in ATM networks. The proposed shaper smoothes video traffics by controling the output rate of the buffer, which is placed in an MPEG source, according to I,B,P frame sequences of MPEG. In performance analysis of an video traffic shaper, a periodic botch arrival model is suggested to describe cell streams in a frame of MPEG video traffic. The queueing model which has periodic independent botch arrival and periodic deterministic service time is used to obtain the cell loss ratio, the mean cell delay, and the measure of smoothing effect. Simulation results are used to validate this queueing model. The cell loss performance of ATM multiplexer is measured by simulation study with real MPEG-1 data. From the viewpoint of traffic load, the cell loss ratio is observed to be considerably high, which is considered to result from the burstiness of MPEG video traffic. As a result, it is shown that the shaping decreases cell loss ratio of multiplexer. The results of this paper can be employed to establish a basic guideline in the implementation of a traffic control scheme and the design of ATM multiplexer for MPEG video traffic.

• Coupled systems mechanics
• /
• v.5 no.4
• /
• pp.355-369
• /
• 2016

Changes in chemical structure have profound effects on the physical properties of epoxy-based materials, and eventually affect the durability of the entire system. Microscopic structural voids generally existing in the epoxy cross-linked networks have a detrimental influence on the epoxy mechanical properties, but the relation remains elusive, which is hindered by the complex structure of epoxy-based materials. In this paper, we investigate the effect of structural voids on the epoxy-based materials by using our developed mesoscale model equipped with the concept of multiscale modeling, and SU-8 photoresist is used as a representative of epoxy-based materials. Developed from the results of full atomistic simulations, the mesoscopic model is validated against experimental measurements, which is suitable to describe the elastic deformation of epoxy-based materials over several orders of magnitude in time- and length scales. After that, a certain quantity of the structure voids is incorporated in the mesoscale model. It is found that the existence of structural voids reduces the tensile stiffness of the mesoscale epoxy network, when compared with the case without any voids in the model. In addition, it is noticed that a certain number of the structural voids have an insignificant effect on the epoxy elastic properties, and the mesoscale model containing structural voids is close to those found in real systems.

• Ocean and Polar Research
• /
• v.31 no.4
• /
• pp.401-414
• /
• 2009

Yellow Sea Buoy (YSB) was moored in the center of the Yellow Sea at 35$^{\circ}$51'36"N, 124$^{\circ}$34'42"E, on 12 September 2007. YSB is a large buoy of 10 m diameter, and as such is more durable against collision by ships and less likely to be lost or removed by fishing nets compared to small ordinary buoys of 2.3 m diameter. YSB is equipped with 12 kinds of oceanic and meteorologic instruments, and transfers its realtime observation data to KORDI through ORBCOMM system every 1 hour. Data on ocean winds, air temperature, air pressure, and sea temperature appear to be accurate, while water property sensors (AAQ1183), which are sensitive to fouling, are producing errors. YSB (2007), Ieodo ocean research station (2003), and Gageocho ocean research station, which was completed in October 2009, will establish the 2 degrees interval by latitude in the Yellow Sea, and they will contribute though the 'Operational Oceanography System' as the important realtime observation network.

• IMMUNE NETWORK
• /
• v.6 no.1
• /
• pp.1-5
• /
• 2006

Background: B cell subset has been divided into B-1 cells and B-2 cells. B-1 cells are found most prominently in the peritoneal cavity, as well as constituting a small pro portion of splenic B cells and they are larger and less dense than B-2 cells in morphology. This study was designed to compare the differences in their proliferation and differentiation between B-1 and B-2 cell. Methods: We obtained sorted B-1 cells from peritoneal fluid and B-2 cells from spleens of mice. Secreted IgM was measured by enzyme-linked immunosorbent assay. Entering of S phase in response to LPS-stimuli was measured by proliferative assay. Cell cycle analysis by propidium iodide was performed. p21 expression was assessed by real time PCR. Results: Cell proliferation and cell cycle progression in B-1 and B-2 cells, which did not occur in the absence of LPS, required LPS stimulation. After LPS stimulation, B-1 and B-2 cells were shifted to Sand G2/M phases. p21 expression by resting B-1 cells was higher than that of resting B-2 cells. Conclusion: B-1 cells differ from conventional B-2 cells in proliferation, differentiation and cell cycle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.10a
• /
• pp.57-60
• /
• 2008

During communication between wireless users, disconnection may occur during the handover process. The high handover latency during the process of handover degrades the service quality of the wireless communications. This problem becomes more crucial if the operation network is transmitting real-time multimedia applications. This paper studies the hanover procedure of mobile IPv6 and investigates various factors affecting the handover latency through mobile IPv6 testbed and evaluates the various parameters for reducing the handover latency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2008.10a
• /
• pp.846-849
• /
• 2008

In recent years there has been growing interest in wireless sensor networks (WSNs) for a variety of indoor applications. In this paper, we present the RSSI-based localization in indoor environments. In order to evaluate the relationship between distance and RSSI, the log-normal path loss shadowing model is used. By tagging users with a sensor node and deploying a number of nodes at fixed position in the building, the RSSI can be used to determine the position of tagged user. This system operates by recording and processing signal strength information at the base stations. It combines Euclidean distance technique with signal strength matrix obtained during real-time measurement to determine the location of user. The experimental results presented the ability of this system to estimate user's location with a accuracy.

• BMB Reports
• /
• v.46 no.12
• /
• pp.600-605
• /
• 2013

Interplay between calcium ions ($Ca^{2+}$) and reactive oxygen species (ROS) delicately controls diverse pathophysiological functions of vascular smooth muscle cells (VSMCs). However, details of the $Ca^{2+}$ and ROS signaling network have been hindered by the absence of a method for dual measurement of $Ca^{2+}$ and ROS. Here, a real-time monitoring system for $Ca^{2+}$ and ROS was established using a genetically encoded hydrogen peroxide indicator, HyPer, and a ratiometric $Ca^{2+}$ indicator, fura-2. For the simultaneous detection of fura-2 and HyPer signals, 540 nm emission filter and 500 nm~ dichroic beamsplitter were combined with conventional exciters. The wide excitation spectrum of HyPer resulted in marginal cross-contamination with fura-2 signal. However, physiological $Ca^{2+}$ transient and hydrogen peroxide were practically measurable in HyPer-expressing, fura-2-loaded VSMCs. Indeed, distinct $Ca^{2+}$ and ROS signals could be successfully detected in serotonin-stimulated VSMCs. The system established in this study is applicable to studies of crosstalk between $Ca^{2+}$ and ROS.