• Journal of Digital Contents Society
• /
• v.17 no.3
• /
• pp.135-142
• /
• 2016

When video service is performed in simulation using NS-2(Network Simulation-2), the video replay is performed as the received frame order. In the existing video replay method based on the received frame order, as the frame orders of receiver and transmitter are different, the receiver buffer does not have the effect that the packets between the frames of transmitter buffer holds a regular size and packet dense and sparsity phenomenon in the receiver buffer is made by the irregular packet size due to the unpredictable reversed order of received partial frames. The above dense and sparsity phenomenon increases the probability of buffer overflow and underflow generation. To prevent these problems, the proposed frame receive order relocation method adds an extra replay buffer which rearranges the order of receive frame as the order of transmit frame, so it has the effect that the packets between the transmit frames keeps a regular size. Through the simulation using NS-2 and JSVM(Joint Scalable Video Model), the generation number of buffer overflow and underflow, and PSNR(Required Peak Signal to Noise Ratio) performance between the existing method and proposed method were compared. As a result, it was found that the proposed method would have better performance than the existing method.

• Journal of Satellite, Information and Communications
• /
• v.9 no.3
• /
• pp.33-40
• /
• 2014

One of the most important requirements for the Ethernet-based automobile is the reliability. In order to achieve this goal, we propose using the High-availability Seamless Redundancy (HSR) protocol (IEC 62439-3 clause 5) in these networks. The HSR protocol provides duplicated frame copies for each sent frame, which means that the destination node will receive at least one copy in case the second copy is lost due to a failure. In other words, there will be no network stoppage even if failure occurs. Moreover, the destination node will receive at least one frame copy with zero-recovery time (seamless) and it will not need to wait to receive the other copy if the first one is lost, which occurs it in the Ethernet standard, as a result of reconfiguration of the network paths. However, the main drawback of the HSR protocol is the unnecessary redundant traffic that is caused by the duplicated frames. Several solutions, including QR, VRing, RURT, and DVP, have already been proposed to improve the traffic performance of the HSR protocol. In this paper, we propose three automobile network topologies. each of which has pros and cons depending on the automobile requirements. Then we applied the HSR protocol with and without the QR and VRing approaches to each scenario. The comparison among these topologies depend on the traffic performance result for each of them. The QR and VRing approaches give a better traffic reduction percentage, ranging from 48% to 75% compared to the standard HSR protocol. Therefore they could limit the redundant traffic in automobile networks when the HSR protocol is used instead of the Ethernet network, which does not provide any seamless recovery if a failure occurs.

• The Journal of the Acoustical Society of Korea
• /
• v.25 no.4E
• /
• pp.154-158
• /
• 2006

In this paper, we suggest a noise estimation method for speech enhancement in nonstationary noisy environments. The proposed method consists of the following two main processes. First, in order to receive fewer affect of variable signals, a best fitting regression line is used, which is obtained by applying a least squares method to coefficient magnitudes in a node with a uniform wavelet packet transform. Next, in order to update the noise estimation efficiently, a differential forgetting factor and a correlation coefficient per subband are used, where subband is employed for applying the weighted value according to the change of signals. In particular, this method has the ability to update the noise estimation by using the estimated noise at the previous frame only, without utilizing the statistical information of long past frames and explicit nonspeech frames by voice activity detector. In objective assessments, it was observed that the performance of the proposed method was better than that of the compared (minima controlled recursive averaging, weighted average) methods. Furthermore, the method showed a reliable result even at low SNR.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.14 no.3
• /
• pp.24-30
• /
• 2015

Wi-Fi STAs in power saving mode described in the Wi-Fi specification can deteriorate the system performance such as throughput, time delay when they receive data frames from a Wi-Fi AP. This problem is caused by data frame reception failure due to the channel state, and it increases re-transmissions. In this paper, we propose a modified power saving mode considering fairness of Wi-Fi system in order to solve the problem. By simulation, we showed that data throughput can be increased without time delay degradation if the proposed method restricting the number of packet transmission attempts and HARQ are used.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.13 no.3
• /
• pp.38-46
• /
• 2014

Wi-Fi STAs in power saving mode described in the Wi-Fi specification can deteriorate the system performance such as throughput, time delay when they receive data frames from a Wi-Fi AP. This problem is caused by data frame reception failure due to the channel state, and it increases re-transmissions. In this paper, we propose a modified power saving mode of Wi-Fi system in order to solve the problem. Also, we evaluate its performance in terms of throughput and time delay by simulation.

• Journal of Biomedical Engineering Research
• /
• v.28 no.3
• /
• pp.429-440
• /
• 2007

A coded excitation has been studied to improve the performance for ultrasound imaging in term of SNR, imaging frame rate, contrast to tissue ratio, and so forth. However, it requires a complicated arbitrary waveform transmitter for each active channel that is typically composed of a multi-bit Digital-to-Analog Converter (DAC) and a linear power amplifier (LPA). Not only does the LPA increase the cost and size of a transmitter block, but it consumes much power, increasing the system complexity further and causing a heating-up problem. This paper proposes an optimized 1.5bit fourth order sigma-delta modulation technique applicable to design an efficient arbitrary waveform generator with greatly reduced power dissipation and hardware. The proposed SDM can provide a required SQNR with a low over-sampling ratio of 4. To this end, the loop coefficients are optimized to minimize the quantization noise power in signal band while maintaining system stability. In addition, the decision level for the 1.5 bit quantizer is optimized for a given input waveform, which results in the SQNR improvement of more than 5dB. Computer simulation results show that the SQNR of a FM(frequency modulated) signal generated by using the proposed method is about 26dB, and the peak side-lobe level (PSL) of its compressed waveform on receive is -48dB.

• Journal of KIISE:Computer Systems and Theory
• /
• v.35 no.4
• /
• pp.150-157
• /
• 2008

This paper presents a design and implementation of realtime video player that operates on a tiled-display system consisting of multiple PCs to provide a very large and high resolution display. In the proposed system, the master process transmits a compressed video stream to multiple PCs using UDP multicast. All slaves(PC) receive the same video stream, decompress, clip their designated areas from the decompressed video frame, and display it to their displays while being synchronized with each other. A simple synchronization mechanism based on the H/W clock of each slave is proposed to avoid the skew between the tiles of the display, and a flow-control mechanism based on the bit-rate of the video stream and a pre-buffering scheme are proposed to prevent the jitter The proposed system is implemented with Microsoft DirectX filter technology in order to decouple the video/audio codec from the player.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.8
• /
• pp.53-64
• /
• 2013

The existing research on the QoS of the Streaming video system(SVS) adjust the video stream being sent from the network perspective, the focus is to prevent data loss and delay. The other hand, changing the quality of the video stream will not receive the guaranteed QoS from the perspective of the users who want uniform quality. In order to solve these problems, this paper applied to ensure that the benefits in the amount of bits per frame occurs Encoder CBR streaming video is kept constant and uniform picture quality advantages of VBR streaming video VBR to CBR Encoder and CBR to VBR Decoder, Video was designed to control the playback stream for And to ensure a uniform quality of the user based on the design and implementation of uniform quality guaranteed SVS. PSNR evaluated for several characteristics of the sample video to demonstrate the superiority of the SVS ensure uniform quality, the proposed Performance evaluation of the SVS ensure uniform quality CBW the ABR from 100% to ensure uniform image quality from 85% to environmental excellence is proved.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.472-478
• /
• 2009

The scopes of the supply chain management in construction projects has expanded from the field management focusing on field storage, transportation, and lifting to the whole supply chain from the materials to field. The expansion of the supply chain management can raise the possibilities of leaner production, which enables shortened lead time of the difficult-to-operate materials, and prevents the work interference or delay. However, the expanded management range requires more information and management than an existing management style currently used for factory production of iron frame, curtain wall, PC, etc. In addition, there are limitations that expand the existing management style into the new supply chain management in construction projects and therefore it is required to automate the existing management style in order to extend the management range. The objective of this study is to propose the process and equipment that can manage the supply chain of the materials which range from the factory production to the field storage based on RFID/USN techniques, introducing small-sized transportation equipment(intelligent pallet), the vehicle tool kit(intelligent trailer), and in-and-out management equipment(Gate Sensor) as a prototype to effectively develop the appliances for operating the proposed process, and present the application possibility of the appliances. The full paper will present then the test results that the proposed appliances for the supply chain management automatically transmit and receive the generated information between the appliances or the appliance and sever under various wireless network circumstances such as zigbee, wibro, Wi-Fi, and CDMA.

• 한국노년학
• /
• v.32 no.2
• /
• pp.447-465
• /
• 2012

The purpose of this study is to examine the life of single aged women receiving minimum living expenses. In order to accomplish desired result, I focus on social exclusion and Resisting women agent. So it provides them practical implication. This study approach life history study of qualitative study. Date were collected from four single aged women. Raw date were analyzed by Mendelbaum analysis frame offering dimension, turnings and adaptation. In research findings, their life was 'Begining of wandering' in childhood and then 'Floating life' since their marriage. After breaking up their husbands, They intend to do 'Existential life'. According to these results, I suggest the necessity of strengthening their own ability and taking the life of human nature.