• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.5729-5744
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• 2017

Vehicular Ad Hoc Networks (VANET) in the large-scale road section usually have typical characteristics of large number of vehicles and unevenly distribution over geographic spaces. These two inherent characteristics lead to the unsatisfactory performance of VANETs. This poor performance is mainly due to fragile communication link and low dissemination efficiency. We propose a novel routing mechanism to address the issue in the paper, which includes a competition-based routing discovery with priority metrics and a local routing repair strategy. In the routing discovery stage, the algorithm uses adaptive scheme to select a stable route by the priorities of routing metrics, which are the length of each hop, as well as the residual lifetime of each link. Comparisons of different ratios over link length and link stability further show outstanding improvements. In the routing repair process, upstream and downstream nodes also compete for the right to establish repair process and to remain as a member of the active route after repair. Our simulation results confirm the improved performance of the proposed algorithm.

• Steel and Composite Structures
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• v.24 no.4
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• pp.441-453
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• 2017

In Y-shaped eccentrically braced frame fabricated with high strength steel (Y-HSS-EBF), link uses conventional steel while other structural members use high strength steel. Cyclic test for a 1:2 length scaled one-bay and one-story Y-HSS-EBF specimen and shake table test for a 1:2 length scaled three-story Y-HSS-EBF specimen were carried out to research the seismic performance of Y-HSS-EBF. These include the failure mode, load-bearing capacity, ductility, energy dissipation capacity, dynamic properties, acceleration responses, displacement responses, and dynamic strain responses. The test results indicated that the one-bay and one-story Y-HSS-EBF specimen had good load-bearing capacity and ductility capacity. The three-story specimen cumulative structural damage and deformation increased, while its stiffness decreased. There was no plastic deformation observed in the braces, beams, or columns in the three-story Y-HSS-EBF specimen, and there was no danger of collapse during the seismic loads. The designed shear link dissipated the energy via shear deformation during the seismic loads. When the specimen was fractured, the maximum link plastic rotation angle was higher than 0.08 rad for the shear link in AISC341-10. The Y-HSS-EBF is a safe dual system with reliable hysteretic behaviors and seismic performance.

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.261-269
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• 2003

The length of the links in an eccentrically braced frame will dictate the behavior of the frame. Link length controls the yielding mechanism and the ultimate failure mode. For short links, the links' shear forces reach the plastic shear capacity before the end moments reach the plastic moment capacity, and the links yields in the shear, forming a shear hinges. These links are termed "shear links." For long links, the end moments reach the plastic moment capacity before the links' shear forces reach the plastic shear capacity, forming moment hinges. These links are termed moment links." In long links, flexural yielding dominates the response, and very high bending strains are required at the link ends to produce large link deformations. In a shear links, the shear force is constant along the length of the links, and the inelastic shear strain are is uniformly distributed over the length of the links. This permits the development of large inelastic link deformations without the development of excessively high local strains. However, The use of eccentrically braced steel frames for the purpose of architectural cionsiderations such as openings and doors, areis dictating the use of longer links, though. Little data areis available on the behavior of long links under cyclic loading conditions. In This paper documents the results of an experimental program is that was conducted to assess the response of moment links in eccentrically braced frames. Sixteen specimens awere tested using a cyclic load.

• Journal of the Korea Safety Management & Science
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• v.6 no.4
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• pp.99-106
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• 2004

In developing criteria for establishing workstation reach limits, it is essential to select the appropriate anthropometric stereotype for solving a specific design problem. The most important factor for comfortable workstation is to eliminate trunk flexion from the neutral (upright) posture. A solution to this design can be developed using population stature and link length data. This paper provides a methodology for design of comfortable workstation using anthropometric stereotype. Application of this methodology can be utilized in various designs for work space including standing and sitting workplace. For the purpose of this study, the data are measured by some parts on body such as stature, arm length, wrist height, elbow height, and shoulder hight. The samples for this study are randomly chosen from university students in Seoul and Kangnung during sixteen months (2003.3-2004.6).

• Current Optics and Photonics
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• v.7 no.1
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• pp.47-53
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• 2023

We propose a centralized passive-optical-network monitoring scheme using the resonance-spectrum properties of a Fabry-Perot cavity based on fiber Bragg gratings. Each cavity consists of two identical uniform fiber Bragg gratings and a varying cavity length or grating length, which can produce a unique single-mode resonance spectrum for the drop-fiber link. The output spectral properties of each cavity can be easily adjusted by the cavity length or the grating length. The resonance spectrum for each cavity is calculated by the transfer-matrix method. To obtain the peak wavelength of the resonance spectrum more accurately, the effective cavity length is introduced. Each drop fiber with a specific resonance spectrum distinguishes between the peak wavelength or linewidth. We also investigate parameters such as reflectivity and bandwidth, which determine the basic performance of the fiber Bragg grating used, and thus the output-spectrum properties of the Fabry-Perot cavity. The feasibility of the proposed scheme is verified using the Optisystem software for a simplified 1 × 8 passive optical network. The proposed scheme provides a simple, effective solution for passive-optical-network monitoring, especially for a high-density network with small end-user distance difference.

• Journal of information and communication convergence engineering
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• v.3 no.1
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• pp.13-17
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• 2005

The link e daggregation between 10GbE switches requires an advanced framistribution method to be properly and efficiently applied. The fixed or dynamic frame distribution methods, formerly proposed, cannot fully utilize the aggregated links, where the receiving terminal only attaches to a pre-specified link among multiple physical links. A frame distribution method using padding is proposed for the link aggregation between 10GbE switches to solve this problem. We compared the performance of the proposed method with those of the static and dynamic frame distribution methods. As a result, the proposed method shows a better performance when the offered load is below 0.7 and the average length of the frames is longer than 954 bytes.

• Journal of Advanced Navigation Technology
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• v.18 no.2
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• pp.158-164
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• 2014

For transmitting the ultra-high speed optical signals with better performance, the techniques to suppress or mitigate the signal distortion due to group velocity dispersion and optical Kerr effects are required. Dispersion management (DM), optical phase conjugation, and the combination of these two are promising techniques to compensate for the signal distortion. However, the fixed length of single mode fiber (SMF) and the fixed residual dispersion per span (RDPS) usually used in these optical links restricts flexible link configuration. The goal of this paper is to investigate the possibility of the flexible configurations of the ultra-high and long-haul optical transmission systems by using the artificial and the random distribution of SMF length and RDPS of each fiber spans consisted of the optical link. It is confirmed that the proposed link configurations should be one of the methods suitable for implementing the flexible optical transmission systems, however which depend on other link parameters, such as the averaged RDPS, and the launch power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9A
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• pp.684-693
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• 2003

This paper analyzes transmissiondelays of a message and a packet in a time-varying and packet-based radio link. The paper assumes that thearrivals of messages have a Bernoulli process and the lengths of the messages a exponential distribution. To reflect the feature of the time-varying radio link, we use a two-state Markov model. From the model the mean transmission delay of and the mean queue length of the packet are analyzed in terms of the packet distribution function, the packet transmission service time, and the PER of the radio link. And the mean message transmission delay time and the mean queue length are derived using the performance indices of the packet. Numerical results show that the message arrival rate and the message length have some bounds to keep the transmission of the message steady and to improve the performance indices of the message. It can be known that the PER of the state influences on the performance indices more than the sojourn time of the state.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.12
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• pp.3883-3891
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• 1996

Performance and productivity of robot manipulator can be improved by increasing its working speed and extending its link length. But heavy weght of the commercial robot links, considered as "rigid body", limits its mazimum working speed and the weght of the links can be reduced for high speed operation. But this light-weight link or long link for special use cannot be consideredas "rigid" structure and vibration of the link due to its flexibility causes errors in end-effector position and orientation. Thus the elastic behaviro of the flexible link should be taken care of for increasing work speed and getting smaller error of end-effector position. In this paper, the fuzzy control theory is selected to design the controller which controlos the joint positions of the robot manipulator and suppress the vibration of flexible link. In the forst place, for the 1 DOF flexible link system, the fuzzy control theory is implemented. The contdroller for the 1 DOF flexible link system is designed. Experimental research is carried out to examine the controllability and the validity of the fuzzy control theory based controller. Next, using the extended desing schemes for the case of the 1 DOF flexible link system and usign the experimental phenomena of the 3 DOF flexible link system, the fuzzy controller for the 3 DOF flexible link system is desinged and experimented.ed and experimented.

• Journal of Korean Society of Transportation
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• v.24 no.5 s.91
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• pp.7-18
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• 2006

Data for travel information Provision are regularly aggregated to Provide travel time information in a reliable and convenient manner and to manage traffic data and information efficiently. In most of practices in Korea, the GPS based travel time data are mainly aggregated every 5 minutes As a result, some probes can't pass by a link within aggregation interval and thereby create uncompleted link passing data. But these data are mostly generated during the congested times and therefore a method that uses such uncompleted link passing data are required. This study estimated queue dissipation length, green time and cycle that use GPS spot speed and developed a link travel time estimation method using such uncompleted link passing data. It also presents method and the overall process of using such data to estimate link travel time in a more accurate manner. As a result, MAPE 1.98% and MAE 4.75 sec of link travel time accuracy improvement has been reported, which is not much different from the real link travel time. The method Proposed here would be an alternative to increase the amount of GPS probe data, especially in congested urban arterial case.