• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.6D
• /
• pp.961-968
• /
• 2006

Curbs and L-type gutters installed at the edge of a road are very important structures to protect pedestrians from traffic accidents and to restraint slip of cars due to rain. However, existing construction method where great parts of the construction progress are done by human power has many problems in workability, quality and cost etc. In this paper, a new construction method for improvement in workability and quality for curbs and L-type gutters is developed. In order to investigate the structural safety and quality of curbs and gutters installed by the new method, tensile and lateral load tests are performed on curbs installed by existing and new methods and uniaxial compression tests are also performed on concrete samples of gutters constructed by existing and new methods. The test results show that the alignment of curbs and the strength of gutter concrete are very much improved by applying the new method. The tensile and lateral load capacities of the curbs installed by the new method are 10.7 and 2.5 times higher than those of curbs by existing method, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5A
• /
• pp.447-456
• /
• 2009

The design comparison and flexural reliability analysis of continuous span composite plate girder bridges are performed. The girders are designed by the methods of allowable stress design (ASD) and load and resistance factor design (LRFD). For the LRFD design, the design specification under development mainly by KBRC, based on AASHTO-LRFD specification in case of steel structures, is applied with the newly proposed design live load which has been developed by analyzing domestic traffic statistics from highways and local roads. For the ASD based design, the current KHBDC code with DB-24 and DL-24 live loads is used. The longest span length for the 3-span continuous bridges with span arrangement ratio of 4:5:4 is assumed to be from 30 m to 80 m. The amount of steel, performance ratios, and governing design factors for the sections designed by the ASD and LRFD methods are compared. In the reliability analysis for the flexural failure of the sections designed by two methods, the statistical properties on flexural resistance based on the yield strength statistics for over 16,000 domestic structural steel samples are applied.

• Journal of Internet of Things and Convergence
• /
• v.10 no.2
• /
• pp.77-84
• /
• 2024

Over the past few years, IoT edges have begun to emerge based on new low-latency communication protocols such as 5G. However, IoT edges, despite their enormous advantages, pose new complementary threats, requiring new security solutions to address them. In this paper, we propose a cloud environment-based IoT edge architecture model that complements IoT systems. The proposed model acts on machine learning to prevent security threats in advance with network traffic data extracted from IoT edge devices. In addition, the proposed model ensures load and security in the access network (edge) by allocating some of the security data at the local node. The proposed model further reduces the load on the access network (edge) and secures the vulnerable part by allocating some functions of data processing and management to the local node among IoT edge environments. The proposed model virtualizes various IoT functions as a name service, and deploys hardware functions and sufficient computational resources to local nodes as needed.

• Convergence Security Journal
• /
• v.24 no.3
• /
• pp.95-104
• /
• 2024

The performance capability of the future battlefield depends on whether the next-generation technology of the Fourth Industrial Revolution, called ABCMS (AI, Bigdata, Cloud, Mobile, Security), can be applied to secure innovative defense capabilities It is no exaggeration to say. In addition, the future military operation environment is rapidly changing into a net work-oriented war (NCW) in which all weapon systems mutually share battlefield information and operate in real-time within a single integrated information and communication network based on the network and is expanding to the scope of operation of the manned and unmanned complex combat system. In particular, communication networks responsible for high-speed and hyperconnectivity require high viability and efficiency in power operation based on multi-tier (defense mobile, satellite, M/W, wired) networks for the connection of multiple combat elements and smooth distribution of information. From this point of view, this study is different from conventional single-media, single-path transmission with fixed specifications, It is an artificial intelligence-based transmission technology using RNN (Recurrent Neural Networks) algorithm and load distribution during traffic congestion using available communication wired and wireless infrastructure multimedia simultaneously and It is the development of MMMP-Multi-Media Multi-Path adaptive network technology.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.1
• /
• pp.11-22
• /
• 2006

Message Signs (VMS) structures offer an increase in traffic safety through their ability to relay massages to motorists for warnings of hazards ahead, traffic congestion, accidents, and lane closings. The geometry of these signs sometimes results in the significant cyclic loading of the supports structure due to wind gusts, which can result from passing trucks or from natural wind. This study presents the results of analytical and experimental investigations of VMS structures. The commercially available softwareGTSTRUDL (2003) was used to perform space-frame structural analyses of these welded tubular structures. Fatigue evaluations were performed using stress ranges from field measurements and from structural analyses. Based on the results of the structural analyses that were conducted, where fatigue design loadings that had been derived from AASHTO Specifications for Structural Supports for Highway Signs, Luminaries, and Traffic Signals (2001) were used, the structures that had been studied were found not to have infinite fatigue life. According to the limited measurements that were made in this study, the fatigue design loadings derived from AASHTO Specifications (2001) appear to be conservative, but they are not overly conservative. The results of this study should be used to make a reasonable design of VMS structures, and to maintain their standards.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.11
• /
• pp.44-52
• /
• 1998

In this paper, we proposed a node architecture and cell routing strategies for ATM applications in WDM multihop networks. The proposed node architecture employs the optical delay loop for storing the cell which is failed in out-link contention. This optical delay loop allows the delay of one cell without the electro-optic conversion. Therefore, we can get the advantages of S&F(Store-and-Forward) routing in Deflection-based all-optical networks. To support the ATM applications efficiently. we considered the transmission priority of ATM cell so that high priority cell can be transmitted with lower loss and shorter delay than low priority one. Two kinds of routing strategies are designed for this architecture: Scheme-Ⅰand Scheme-Ⅱ. Scheme-Ⅰapplies S&F routing to high cell and Deflection routing to low cell, i.e., high cells are routed along the shortest path based on S&F routing, but low cells are deflected or lost. Schem-Ⅱ is similar to Scheme-Ⅰexcept that low cells can occupy the optical loop if it is available. This Scheme-Ⅱ increases the utilization of network resources without decreasing the throughput of high cell by reducing the low cell loss rate when traffic load is low. Simulation results show that our routing strategies have better performance than conventional ones under non-uniform traffic as well as uniform traffic.

• International Journal of Highway Engineering
• /
• v.18 no.4
• /
• pp.19-28
• /
• 2016

PURPOSES : Long-life asphalt pavements are used widely in developed countries. In order to be able to devise an effective maintenance strategy for such pavements, in this study, we evaluated the performance of the long-life asphalt pavements constructed along the national highways in South Korea. Further, an economic evaluation of the long-life asphalt pavements was performed based on a life-cycle cost analysis. We aimed to devise a model for evaluating the performance of long-life asphalt pavements using the national highway pavement management system (PMS) database as well as for analyzing the economic feasibility of such pavements, in order to promote their use in South Korea. METHODS : The maintenance history and pavement performance data were obtained from the national highway PMS database. The pavement performances for a total of 292 sections of 10 lanes (5 northbound lanes and 5 eastbound lanes) of national highways were used in this study. Models to predict the performances of hot mix asphalt (HMA) and long-life asphalt pavements under two distinct traffic conditions were developed using a simple regression method. Further, the economic feasibility of long-life asphalt pavements was evaluated using the Korea Pavement Management System (KoPMS). RESULTS : We developed service-life prediction models based on the traffic volume and the equivalent of single-axle load and found that long-life asphalt pavements have service lives 50% longer than those of HMA pavements. Further, the results of the economic analysis showed that long-life asphalt pavements are superior in terms of various economic indexes, including user cost, delay cost, total cost, and user benefits, even though their maintenance cost is higher than that of HMA pavements. A comparison of the economic feasibilities of the various groups showed that group A is superior to HMA pavements in all aspects except in terms of the maintenance criterion (crack 20% or higher) as per the NPV index. However, the long-life asphalt pavements in group B were superior in terms of the maintenance criterion (crack 25% or higher) regardless of the economic feasibility. CONCLUSIONS : The service life of long-life asphalt pavements was found to be approximately 50% longer than that of HMA pavements, regardless of the traffic volume characteristics. The economic feasibility of long-life asphalt pavements was evaluated based on the KoPMS. The results of the economic analysis were the following: long-life asphalt pavements are exceptional in terms of almost all factors, such as user cost, delay cost, total cost, and user benefit; however, the exception is the maintenance cost. Further, the economic feasibility of the long-life asphalt pavements in group B was found to be better than that of the HMA pavements (crack 25% or higher).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.10
• /
• pp.151-157
• /
• 2018

Among the various sensors for measuring traffic, PVDF (polyvinylidene fluoride) piezoelectric sensors are used to classify vehicles because they can detect the axle of the vehicle. Piezoelectric sensors are embedded in road pavements and are always exposed to traffic loads and environmental loads. Therefore, the life expectancy is very short, less than 6 years. Traffic control is essential for reinstallation and data collection is interrupted during the failure period. The lifespan will increase if the sensor installation depth is increased. In this study, the sensor signal output was analyzed with a variable depth of sensor installation to verify the possibility of deeper installation. Furthermore, various parameters, such as the weight and speed, were analyzed. The wheel load is applied using APT. As a result, the MSI BL sensor output signal is higher than 100mV when installed at 3cm, which is reliable. If the location of the sensor is deeper in the pavement, the expected lifetime of the sensor is also increased. On the other hand, the MSI cable was found to be less than 100mV at the shallowest depth of 1cm, making it impossible for field applications.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.6
• /
• pp.17-29
• /
• 1999

In this paper, the prioritized queueing handoff scheme in CDMA (Code Division Multiple Access) cellular system is proposed. Also, the analytical survey for the proposed scheme is carried out, and the performance of this scheme is compared with that of non prioritized scheme and FIFO (First In First Out) queue scheme by computer simulation. The handoff region is defined as the time between the handoff treshold and the receiver threshold, and it is used for the maximum queue waiting time in the proposed scheme. The handoff and the receiver thresholds are defined as rewpectively: 1) the time that the Pilot Strength Measurement Message in the neighbor in the neighbor cell is received to the BS (Base Station) under the T_ADD threshold; and 2) the time that the T_DROP timer is expired and the Pilot Strength Measurement Message in the current cell is received to the BS under the T_DROP threshold. The performance metrics for analyzing the proposed scheme are : 1) probability of forced termination; 2) probability of call blocking; 3) ratio of carried traffic to total offered load; 4) average queue size; 5) average handoff delay time in queue. The simulation results show that the proposed scheme maintains high performance for handoff requests at a small penalty in total system capacity.

• Journal of Broadcast Engineering
• /
• v.25 no.1
• /
• pp.94-104
• /
• 2020

Currently media consumption over fixed/mobile Internet is mostly conducted by adaptive media streaming technology such as DASH (Dynamic Adaptive Streaming over HTTP), which is an ISO/IEC MPEG (Moving Picture Experts Group) standard, or some other technologies similar to DASH. All these heavily depend on the HTTP caches that ISPs (Internet Service Providers) are obliged to provide sufficiently to make sure fast enough Web services. As a result, as the number of media streaming users increases, ISPs' burden for HTTP cache has been greatly increased rather than CDN (Content Delivery Network) providers' server burden. Hence ISPs charge traffic cost to CDN providers to compensate for the increased cost of HTTP caches. Recently in order to reduce the traffic cost of CDN providers, P2P (Peer-to-Peer)-assisted DASH system was proposed and a peer selection algorithm that maximally reduces CDN provides' traffic cost was investigated for this system. This algorithm, however, tends to concentrate the burden upon the selected peer. This paper proposes a new peer selection algorithm that distributes the burden among multiple peers while maintaining the proper reduction level of the CDN providers' cost. Through implementation of the new algorithm in a Web-based media streaming system using WebRTC (Web Real-Time Communication) standard APIs, it demonstrates its effectiveness with experimental results.