• Title/Summary/Keyword: Packet structure

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Development of Non-destructive Evaluation Method for Composite Structures using Tapping Sound (타격음을 이용한 복합재료 구조물의 비파괴 검사법 개발)

  • 황준석;김승조
    • Composites Research
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    • v.17 no.1
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    • pp.1-9
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    • 2004
  • A new non-destructive evaluation method using tapping sound is proposed. This method, named Tapping Sound Analysis, is using the difference between tapping sound data of healthy structure and defective structure as the criteria of determination of internal defect of composite structure. For the characterization of tapping sound, a feature extraction method based on wavelet packet transform is proposed. And a feature index is defined for the decision of existence of internal defects. To prove the possibility of proposed method as a non-destructive evaluation method, experimental study is performed. The tapping sound data of healthy structure and defective structure are measured and compared based on the proposed decision method. The experimental results showed that the feature index is a good indicator for the determination of internal defects.

Damage Evaluation of a Framed Structure Using Wavelet Packet Transform (웨이블렛펙킷 변환을 이용한 프레임 구조물의 건전성 평가)

  • Kim, Han Sang
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.3
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    • pp.159-166
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    • 2007
  • This paper evaluates the soundness of structural elements using Wavelet Packet Transform (WPT). WPT is applied to the response acceleration of a framed structure which is subjected to earthquake load to decompose the response acceleration, then the energy of each component is calculated. The first five largest components in energy magnitude among the decomposed components are selected as input to an ANN to identify the damage location and severity. Two nodes in output layer yield damaged element and damage severity respectively. This method successfully evaluates the amount of damage and its location in the structure.

A Wireless Downlink Packet Scheduling Algorithm for Multimedia Traffic (멀티미디어 트래픽에 대한 무선 환경에서의 순방향 패킷 스케줄링 알고리즘)

  • 김동회;류병한
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.39 no.12
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    • pp.539-546
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    • 2002
  • In this paper, we consider a wireless multimedia environment to service both real-time video traffic and non-real-time WWW-application traffic In our suggested new packet scheduling algorithm, we consider both the accumulation counter and SIR to reduce delay in real-time traffic. In addition, our packet scheduling algorithm gives priority first to real-time video traffic service and then to non-real-time internet Packet service when real-time traffic service is absent. From the simulation results, we find that the AC (Accumulation Counter) scheme has much smaller delay than the conversional M-LWDF scheme for real-time video data users, which has a special quality sensitive to its own delay. We also consider the transmission structure of using both the frame period in the time-axis and the OVSF codes in the code-axis at the same time, which is similar to the structure of HSDPA system.

A Comparison of 20 and 3D MMORPG's Traffic (2D와 3D에 기반한 MMORPG 트래픽간의 특성 비교)

  • Kim, Jae-Cheol;Kwon, Tae-Kyoung;Choi, Yang-Hee
    • Journal of Information Technology Services
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    • v.7 no.2
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    • pp.137-148
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    • 2008
  • This paper measures and compares the traffic of a series of Massively Multi-player On-line Role Playing Game (MMORPG). The purpose of this analysis is to characterize the MMORPG traffic and compare the traffic characteristics of those games caused by the game structure difference between 2D and 3D environment. The target game is 'Lineage I' and 'Lineage II' which represent world's largest MMORPGs in terms of the number of concurrent users. We collect about 280 giga bytes and 1 tera bytes of packet headers, respectively. We compare packet size, packet inter-arrival time and bandwidth usage of these two games. The MMORPG traffic consists of two kinds of packets: client-generated upstream packets and server-generated downstream packets. We observe that the upstream packet size of payload has grown from 9 bytes to 19 bytes, while the average payload size of downstream packets has grown from 37 bytes to 318 bytes. This asymmetry of growing rate is caused by 3D game structure. Packet inter-arrival time becomes shorter from average 2 milliseconds to 58 microseconds. Bandwidth consumption per client has grown from 4 kbps to 20 kbps. We find that there is a linear relationship between the number of users and the bandwidth usage in both case.

Experimental Study on the Three-Dimensional Topology of Hairpin Packet Structures in Turbulent Boundary Layers (난류경계층의 3차원 헤어핀 다발구조에 대한 실험적 연구)

  • Kwon, Seong-Hun;Yoon, Sang-Youl;Kim, Kyung-Chun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.7
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    • pp.834-841
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    • 2004
  • Experimental study on the three-dimensional topology of hairpin packet structures in turbulent boundary layers were carried out. Two different Reynolds number based on momentum thickness, Re$\sub$$\theta$/=514 and 934 were generated in a blowing type wind tunnel under the condition of zero pressure gradient. Simultaneous measurements of velocity fields at a wall-normal plane and wall-parallel plane by a plane PIV and a Stereo-PIV systems. The two Nd:Yag laser systems and three CCD cameras were synchronized to obtain instantaneous velocity fields at the same time. To avoid optical noise at the crossing line by the two laser light sheets, a new optical arrangement using polarization was applied. The obtained velocity fields show the existence of hairpin packet structure vividly and the idealized hairpin vortex signature is confirmed by experiment. Two counter-rotating vortex pair which reflects the cutting plane of hairpin legs are found both side of a strong streaky structure when the wall-normal plane cuts the hairpin head.

Implementation of Packet Voice Protocol (패킷음성 프로토콜의 구현)

  • 이상길;신병철;김윤관
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.18 no.12
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    • pp.1841-1854
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    • 1993
  • In this paper, the packet voice protocol for the transmission of voice signal onto ethernet is implemented in a personal computer (PC). The packet voice protocol used is a modified one from CCITT G.764 packetized voice protocol. The hardware system to facilitate the voice communication onto ethernet is divided into telephone interface, speech processing, PC interface and controllers. The software structure of the protocol is designed according to the OSI seven layer architecture and is divided into three routines : ethernet device driver, telephone interface, and processing routine of the packet voice protocol. Experiments through ethernet with telephone interface show that this packet voice communication achieves satisfactory quality when the network traffic is light.

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Design and Implementation of Multi-Gigabit Packet Receiver Algorithms based on ECMA Standard (ECMA 표준에 기반한 Multi-Gigabit Packet 수신기 알고리듬 설계 및 구현)

  • Lee, Yong-Wook;Oh, Wang-Rok
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.46 no.3
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    • pp.26-31
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    • 2009
  • In this paper, we propose the receiver algorithms suitable for the ECMA standard proposed for multi-gigabit packet transmission in 60 GHz band. In the ECMA standard, various modulation schemes are used for system flexibility. Hence, it is crucial to develop receiver algorithms supporting various modulation schemes with an uniform hardware structure. In this paper, we propose the receiver algorithms supporting DBPSK, DQPSK and OOK modulation schemes simultaneously. The proposed algorithms are not only hardware efficient but also support various modulation schemes with an uniform hardware structure.

SRN Hierarchical Modeling for Packet Retransmission and Channel Allocation in Wireless Networks (무선망에서 패킷 재전송과 채널할당 성능분석을 위한 SRN 계층 모델링)

  • 노철우
    • The KIPS Transactions:PartC
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    • v.8C no.1
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    • pp.97-104
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    • 2001
  • In this paper, we present a new hierarchical model for performance analysis of channel allocation and packet service protocol in wireless n network. The proposed hierarchical model consists of two parts : upper and lower layer models. The upper layer model is the structure state model representing the state of the channel allocation and call service. The lower layer model, which captures the performance of the system within a given structure state, is the wireless packet retransmission protocol model. These models are developed using SRN which is an modeling tool. SRN, an extension of stochastic Petri net, provides compact modeling facilities for system analysis. To get the performance index, appropriate reward rates are assigned to its SRN. Fixed point iteration is used to determine the model parameters that are not available directly as input. That is, the call service time of the upper model can be obtained by packet delay in the lower model, and the packet generation rates of the lower model come from call generation rates of the upper model.

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FPGA Inplementation of the Extended ATA Interface (확장된 ATA 인터페이스의 FPGA구현)

  • 구대성;김정태;이강현
    • Proceedings of the IEEK Conference
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    • 1999.11a
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    • pp.1037-1040
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    • 1999
  • In this paper, we designed the extended ATA(AT Attachment interface with extension) interface that combines with goods price and ability and intellectual behavior of SCSI, for make progress the ability and structure of ordinary interface for connect with device of using PC. ATA is establish a standard of IDE(Intelligent Drive Electronics) public in small form factor. SCSI bus is device behaving intellectual and have stable hardware structure, calssified instructions structure. But it is device that difficult to buy, because of price of more than two times. The other side, ATA device is worse than SCSI bus in part of ability, but it came to SCSI in part of speed after improve and it's price is less expensive. another improvement of ATA is a standard of ARAP(AT Attachment Packet Interface) and use method of packet transmission and behaves as if SCSI use a method. Finally, improvement of ATAPI behave from interface of only HDD to ability of ordinary interface. This paper propose the structure of extended interface that satisfied the price and ability.

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Damage detection in stiffened plates by wavelet transform

  • Yang, Joe-Ming;Yang, Zen-Wei;Tseng, Chien-Ming
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.3 no.2
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    • pp.126-135
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    • 2011
  • In this study, numerical analysis was carried out by using the finite element method to construct the first mode shape of damaged stiffened plates, and the damage locations were detected with two-dimensional discrete wavelet analysis. In the experimental analysis, four different damaged stiffened structures were observed. Firstly, each damaged structure was hit with a shaker, and then accelerometers were used to measure the vibration responses. Secondly, the first mode shape of each structure was obtained by using the wavelet packet, and the location of cracks were also determined by two-dimensional discrete wavelet analysis. The results of the numerical analysis and experimental investigation reveal that the proposed method is applicable to detect single crack or multi-cracks of a stiffened structure. The experimental results also show that fewer measurement points are required with the proposed technique in comparison to those presented in previous studies.