• Title/Summary/Keyword: connection time

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Active monitoring of pipeline tapered thread connection based on time reversal using piezoceramic transducers

  • Hong, Xiaobin;Song, Gangbing;Ruan, Jiaobiao;Zhang, Zhimin;Wu, Sidong;Liu, Guixiong
    • Smart Structures and Systems
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    • v.18 no.4
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    • pp.643-662
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    • 2016
  • The monitoring of structural integrity of pipeline tapered thread connections is of great significance in terms of safe operation in the industry. In order to detect effectively the loosening degree of tapered thread connection, an active sensing method using piezoceramic transducers was developed based on time reversal technique in this paper. As the piezoeramic transducers can be either as actuators or sensors to generate or detect stress waves, the energy transmission for tapered thread connection was analyzed. Subsequently, the detection principle for tapered thread connection based on time reversal was introduced. Finally, the inherent relationship between the contact area and tightness degree of tapered thread connection for the pipe structural model was investigated. Seven different contact area scenarios were tested. Each scenario was created by loosening connectors ranging from 3 turns to 4.5 turns in the right tapered threads when the contact area in the left tapered threads were 4.5 turns. The experiments were separately conducted with a highly noisy environment and various excitation signal amplitudes. The results show the focused peaks based on time reversal have the monotonously rising trend with the increase of the contact areas of tapered threads within an acceptable monitoring resolution for metal pipes. Compared with the energy method, the proposed time reversal based method to monitor tapered threads loosening demonstrates to be more robust in rejecting noise in Structural Health Monitoring (SHM) applications.

Performance comparison of application signalling protocol on B-ISDN bearer connection types (B-ISDN 베어러 연결 형태에 따른 응용 신호 프로토콜의 성능 비교)

  • 이성근;유상신;김덕진
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.5
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    • pp.44-54
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    • 1996
  • Various types of B-ISDN bearer connection can take place according to access types of endpoint equipments in call and number of connectio between endpoints. In this paper, performance of application signalling protocol on three basic facilities of B-ISDN CS-2 signalling system, such as connection of point-to-point, point-to-multipoint and multiconnection call, is evaluated and compared. For performacne evaluation, experimental model of B-ISDN application signalling protocol is implemented and respective message processing time of each process is measured. By applying message processing time to local exchange system, cal processing capacity of application signalling protocol on three basic connection types is evaluated by simulation method. In this paper, local exchange system is considered to have two ATM NNI links and four ATM UNI links.

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Dynamic Behavior of 2D 8-Story Unbraced Steel Frame with Partially Restrained Composite Connection (합성반강접 접합부를 갖는 2차원 8층 비가새 철골골조의 동적거동)

  • Kang, Suk Bong;Lee, Kyung Taek
    • Journal of Korean Society of Steel Construction
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    • v.19 no.5
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    • pp.503-513
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    • 2007
  • The seismic responses of a building are affected by the connection characteristics that have effects on structural stiffness. In this study, push-over analysis and time history analysis were performed to estimate structural behavior of 2D eight-story unbraced steel structures with partially restrained composite connections using a nonlinear dynamic analysis program. Nonlinear $M-{\theta}$characteristics of connection and material inelastic characteristics of composite beam and steel column were considered. The idealization of composite semi-rigid connection as fully rigid connection yielded an increase in initial stiffness and ultimate strength in the push-over analysis. In time history analysis, the stiffness and hysteretic behavior of connections have effects on base-shear force, maximum story-drift and maximum moment in beams and columns. For seismic waves with PGA of 0.4 g, the structure with the semi-rigid composite connections shows the maximum story-drift with less than the life safety criteria by FEMA 273 and no inelastic behavior of beam and column, whereas in the structure with rigid connections, beams and columns have experienced inelastic behaviors.

Characteristics of Hybrid-Type SFCL according to the Parallel Connection of Secondary Windings (2차권선의 병렬연결에 따른 하이브리드형 초전도 한류기의 특성)

  • Hwang, Jong-Sun;Cho, Yong-Sun;Choi, Hyo-Sang
    • Proceedings of the KIEE Conference
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    • 2006.10b
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    • pp.208-211
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    • 2006
  • We have analyzed operating characteristics of hybrid-type superconducting fault current limiter (SFCL) according to the parallel connection of secondary windings with $YBa_{2}Cu_{3}O_{7}$ (YBCO) films. The turn ratio between the primary and secondary windings of each reactor was 63:21. Hybrid-type SFCL using a transformer with parallel reactors could reduce the unbalanced quench caused by differences of the critical current density between YBCO films. We found that hybrid-type SFCL having parallel connection induced simultaneous quench between the superconducting elements. The quench-starting point at this time was almost same. When the applied voltage was 200V, the limiting current in the hybrid-type SFCL with a serial connection was lowered to 34 percent than that in the SFCL with a parallel connection. In the meantime, when the voltage generated in the superconducting elements was the same, the current value in the parallel connection was 60 percent less than in the serial connection. The voltage generated in the primary winding also showed the similar behavior. In conclusion, we found that the fault current was limited more effectively in the SFCL with the serial connection but the power burden of the superconducting elements was reduced in the parallel connection.

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Mobile Phone Dependency, Motivations and Effects of Mobile Phone Usage Among Korean Adolescents (청소년의 휴대전화 의존, 이용동기 및 결과에 관한 연구)

  • Sung, Yun Sook
    • Korean Journal of Child Studies
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    • v.29 no.4
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    • pp.181-197
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    • 2008
  • A mobile phone usage survey was administered to a nationwide sample of 3,617 adolescents. Major motivations of mobile phone usage were mobility/real-time connection, show off, information acquisition, entertainment, dialogue, schedule management, and advice. Maintenance of social relationship with the peer group was most important in mobile phone use. Motivations influenced mobile phone dependency : show off had the strongest influence on anxiety/paranoia followed by dialogue, entertainment, mobility/real-time connection. Without their phones, fashion-oriented adolescents showed mobile phone dependency and anxiety. Stronger dialogue and entertainment motivations were associated with weaker real time connection motivation and stronger paranoia symptoms. Mobile phone dependent adolescents had lower grades, showed lack of attention, had little dialogue with their parents and showed withdrawal from the peer group.

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Sparse Reconfigurable Adaptive Filter with an Upgraded Connection Constraint Algorithm

  • Chang, Hong;Hwang, Suk-Seung
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.11 no.4
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    • pp.305-309
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    • 2011
  • A sparse reconfigurable adaptive filter (SRAF) based on a photonic switch determines the appropriate time delays and weight values for an optical switch implementation of tapped-delay-line (TDL) systems. It is well known that the choice of switch delays is significantly important for efficiently implementing the SRAF. If the same values exist as calculating the sum of weight magnitudes for implementing the connection constraint required by the SRAF, conventional connection algorithm based on sequentially selection the maximum elements might not work perfectly. In an effort to increase the effectiveness of system identification, an upgraded connection algorithm used progressive calculation to obtain the better solution is considered in this paper. The performance of the proposed connection constraint algorithm is illustrated by computer simulation for a system identification application.

Development of Top-Down Connection System to Solve the Problem of Construction Tolerances in Installing Prefabricated Beams to Pre-founded Columns (시공오차가 있는 선기초기둥에 공장제작보의 설치가 용이한 탑다운공사용 접합기술개발)

  • Kim, Seung-Weon;Jung, Hee-Weon;Park, Dae-Yung;Kim, Dong-Gun;Park, Joo-Hyun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.05b
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    • pp.25-30
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    • 2011
  • Almost prefounded columns for top-down construction certainly have construction tolerances in plan and plumbness. Therefore, it is very difficult to connect prefabricated beams to prefounded columns at each floor level after excavation by usual top-down connection method and this usual connection method leads to long construction time, increasing cost and decreasing quality. This paper presents a new method for connecting prefabricated beam to prefounded column with GROUT-JACKET CONNECTION SYSTEM consisting of sleeve, bearing-shear bands and grout. Details and illustrations of the connections and applications by GROUT-JACKET CONNECTION SYSTEM for the top-down construction are also included in this paper.

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Implementation of steel connection and interface using Xsteel (Xsteel을 사용한 접합부 자동화 시스템의 구현 및 인터페이스 형성)

  • 조효남;조영상;박미연;이승근
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.305-312
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    • 2003
  • Recently, with a progressive development of hardware of computer, the internet and network technology, the environment of construction varies rapidly due to increase the complex form in structure shape and system. With variations, the CAD system for design and products also varies from 2D system to 3D system. This study mainly deals with the methodology of automatic connection design of 3D CAD system, steel connection system (XSteel) using macro. First, using design program in the steel connection system, Xsteel, the joint connection macro will be made up and established the detail classes of design. The next, Database Program (Converter Program) related to the general structural analysis program (MIDAS) and the steel connection program (Xsteel) is constructed for data interface between two programs. From this study, if the merits of 3D CAD system and converter program are utilized well, it is expected that the time needed in modeling and the amounts due to material loses decrease gradually.

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Intelligent Diagnostic System of Photovoltaic Connection Module for Fire Prevention (화재 예방을 위한 태양광 접속반의 지능형 진단 시스템)

  • Ahn, Jae Hyun;Yang, Oh
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.161-166
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    • 2021
  • To prevent accidents caused by changes in the surrounding environment or other factors, various protection facilities are installed at the photovoltaic connection module. The main causes of fire are sparks due to foreign substances inside the photovoltaic connection module through high temperature rise and dew condensation in the photovoltaic connection module, and fire due to heat from the power diode. The proposed method can predict the fire by measuring flame, carbon dioxide, carbon monoxide, temperature, humidity, input voltage, and current on the photovoltaic connection module, and when the fire conditions are reached, fire alarm and power off can be sent to managers and users in real time to prevent fire in advance.

Design of a bluetooth-based interactive control network

  • Kwak, Jae-Hyuk;Lim, Joon-Hong
    • 제어로봇시스템학회:학술대회논문집
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    • 2004.08a
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    • pp.922-925
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    • 2004
  • Bluetooth technology is essentially a method for wireless connection of a diverse set of devices ranging from PDAs, mobile phone, notebook computers, to another equipments. The bluetooth system supports both point-to-point connection and point-to-multipoint connections. In point-to-multipoint connection, the channel is shared among several bluetooth devices. Two or more devices sharing the same channel form a piconet. There is one master device and up to seven active slave devices in a piconet. The radio operates in the unlicensed 2.45GHz ISM band. This allows users who travel world-wide to use bluetooth equipments anywhere. Since the link is based on frequency-hop spread spectrum, multiple channels can exist at the same time. The Bluetooth standard has been suggested that Bluetooth equipments can be used in the short-range, maximum 100 meters . It has been defined that the time takes to setup and establish a bluetooth connection among devices is 10 seconds. It is a long time and may be a cause to lose a chance of finding other non-fixed devices. We propose a routing protocols for scatternets which can be used to control a mobile units(MUs) in this network. The proposed routing protocol is composed of two kinds of bluetooth information, access point(AP) and MU.

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