• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.591-604
• /
• 2008

In this study, two design examples of drilled shafts on soft ground in Ho-Chi-Minh City, Vietnam are introduced. One is for a 27-story apartment and the other is for a Arch bridge over Saigon river. Unlikely the normal cases in Korea, all of the bored pile foundations are supposed to be placed on soil layers. Therefore, skin friction between pile and ground is the most crucial design parameter. Three methods using SPT N value of sandy soil -Korean Road Bridge Code(1996), Reese and Wright (1977), and O'Neill and Reese (1988)- were adopted to obtain an ultimate axial bearing capacity. In order to verify the calculated bearing capacity, 3 sets of static load test and a Osterberg Cell test were performed at an apartment site and a bridge site respectively. LRFD (Load Resistance Factored Design) method was compared with ASD (Allowable Stress Design) method. On application of ASD method, safety factor for skin friction was adopted as 2 or 3 while safety factor for end bearing was 3. The design bearing capacities from ASD method matched well with those from LRFD method when safety factor for skin friction was adopted as 2.

• Advances in concrete construction
• /
• v.7 no.1
• /
• pp.11-22
• /
• 2019

A comprehensive assessing approach for durability of reinforced concrete structures dealing with the corrosion process of rebar subjected to the attack of aggressive agent from environment was proposed in this paper. Corrosion of rebar was suggested in the form of combination of global corrosion and pitting. Firstly, for the purposed of considering the influence of rebar's radius, a type of Plane Corrosion Model (PCM) based on uniform corrosion of rebar was introduced. By means of FE simulation approach, global corrosion process of rebar regarding PCM and LCM (Linear Corrosion Model) was regressed and compared according to the data from Laboratoire $Mat{\acute{e}}riaux$ et $Durabilit{\acute{e}}$ des Constructions (LMDC). Secondly, pitting factor model of rebar in general descend law with corrosion degree was introduced in terms of existing experimental data. Finally, with the comprehensive numerical simulation, the durability of an existing arch bridge was studied in depth in deterministic way, including diffusion process and sectional strength of typical cross section of arch, crossbeam and deck slab. Evolution of structural capacity considering life-cycle rehabilitation strategy indicated the degradation law of durability of reinforced arch bridges.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2008.04a
• /
• pp.184-189
• /
• 2008

In this study, an artificial wheel load generation method is proposed to assist practical engineers performing dynamic analysis with simple procedure. To generate an artificial wheel loads from running vehicle, PSD(Power Spectrum Density) profiles of actual wheel load were sampled in terms of various road roughnesses. A detailed truck and bridge models were used for sampling actual wheel load to represent the real motion of moving vehicle. These wheel load profiles were simplified for the artificial wheel load. The simplification of actual wheel load profiles was performed by regression analysis. The result showed that the artificial wheel load well represents the real profiles of wheel load.

• Journal of information and communication convergence engineering
• /
• v.18 no.3
• /
• pp.183-187
• /
• 2020

The general Wi-Fi network connection structure is that a number of IoT (Internet of Things) sensor nodes are directly connected to one AP (Access Point) node. In this structure, the range of the network that can be established within the specified specifications such as the range of signal strength (RSSI) to which the AP node can connect and the maximum connection capacity is limited. To overcome these limitations, multiple middleware bridge technologies for dynamic scalability and load balancing were studied. However, these network expansion technologies have difficulties in terms of the rules and conditions of AP nodes installed during the initial network deployment phase In this paper, an intelligent edge computing IoT device is developed for constructing an intelligent autonomous cluster edge computing network and applying it to real-time road danger context aware and notification system through an intelligent risk situation recognition algorithm.

• International Journal of Internet, Broadcasting and Communication
• /
• v.9 no.1
• /
• pp.18-23
• /
• 2017

In 2015, 100-car pileup was happened because the safe distance from the car in front did not be kept due to much fog at YoungJong Bridge in South Korea. This is why the road would be benumbed with cold weather in winter. For this weather condition, if the driver of the car in front changed the lane suddenly or suddenly slammed on the brake in fog or freezing area, the braking distance of the real car has to be 2 or 3 times longer than usual. In this paper, we have simulated the function that warns and notice about the fog area or the freezing one in the road using Arduino sensors and Beacon. Also we propose the intelligent traffic system to protect the accidents in winter.

• Journal of Environmental Impact Assessment
• /
• v.20 no.5
• /
• pp.697-703
• /
• 2011

The purpose of this study aims to preserve biodiversity in increasingly fragmented green patches for spatial analysis of planting on the eco-corridors and to optimize the target species, the location, width, cross section of the eco-corridors. It was suggested that eco-corridors should have to planned at early stages of road planning so that the number and locations of eco-corridors in advance. Ecological corridor is the facility to connect two habitats fragmented by road, dam, housing and industrial area. And, everyone agree that ecological corridor is important useful structural component that help animal movement in fragmented landscapes. However, ecological corridors have many problems of the recorded the size of corridor, planting species to nearby exiting vegetation species and structure. The most important facts that there are no consideration for location of animal migration and behavior using eco-corridors. This study was carried out to spatial analysis of eco-corridors location, satellite data and GIS were used to analyze for searching optimum location of the eco-corridors.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.4 no.4
• /
• pp.129-140
• /
• 2000

Retaining wall is a constructed structure in order to construct road, rail, building for effective use and obtainments of the limited ground. Recently, many kinds of research have been actively developed for a standardization and information to the maintenance and management of bridge, tunnel, road. With the works of database construction of that, many kinds of data with respect to statistics is cumulated. Database work of retaining wall is wholly lacking and lagged behind in the works of database construction. This paper suggests classification system on inspection data. On the basis of that, code work with classification system was practised and DB program of inspection data of retaining wall was developed. And input work for a data of maintenance and management was practised. The purpose of this paper is to suggest a kind of statistics data and investigate a characteristics of inspection using statistic data on retaining wall.

• International conference on construction engineering and project management
• /
• 2015.10a
• /
• pp.606-607
• /
• 2015

The traffic volume on the road shows various trends reflecting regional characteristics for monthly and hourly, and economic loss affecting users varies according to the selected period for the maintenance of road pavements. Therefore, in this study, the user cost (or delay cost) for monthly and hourly on the work zone near the Maesang Bridge Section on Poseung-Gu, Pyeongtaek-si, Gyeonggi-do was calculated using the time series models and VISSIM, and based on the result, the effect of user cost reduction according to the selection of best maintenance period was examined. The analysis result showed that the month of the lowest user cost occurred due to the maintenance of target section was January (10,293,258 KRW/Day×1km) and the month of the greatest user cost occurred was November (13,337,495 KRW/Day×1km).

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• 2007.11a
• /
• pp.167-174
• /
• 2007

This study proposes a practical and realistic method to establish an optimal lifetime maintenance strategy for deteriorating bridges by considering the life-cycle performance as well as the life-cycle cost. The proposed method offers a set of optimal tradeoff maintenance scenarios among other conflicting objectives, such as minimizing cost and maximizing performance. A genetic algorithm is used to generate a set of maintenance scenarios that is a multi-objective combinatorial optimization problem related to the and the life-cycle cost and performance as separate objective functions. A computer program, which generates optimal maintenance scenarios, was developed based on the proposed method. The subordinate relation between bridge members has been considered to decide optimal maintenance sequence. The developed program has been used to present a procedure for finding an optimal maintenance scenario for steel-girder bridges on the Korean National Road. Through this bridge maintenance scenario analysis, it is expected that the developed method and program can be effectively used to allow bridge managers an optimal maintenance strategy satisfying various constraints and requirements.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.3
• /
• pp.60-68
• /
• 2017

Since the bridge is the main facility of the road that is the core of the civil infrastructure, the bridge is constructed to ensure stability and serviceability during the traffic use. In order to secure the safety of bridges, evaluating the integrity of bridges at present is an important task in the maintenance work of bridges. In general, to evaluate the load carrying capacity of bridges, it is possible to confirm the superimposed behavior and symmetric behavior of bridges by estimating the lateral load distribution factor of the bridges through vehicle loading tests. However, in order to measure the lateral load distribution factor of a commonly used bridge, a static loading test is performed. There is a difficulty in traffic control. Therefore, in this study, the static displacement component of the bridge measured in the dynamic loading test and the ambient vibration test was extracted by using empirical mode decomposition technique. The lateral load distribution was estimated using the extracted static displacement component and compared with the lateral load distribution factor measured in the static loading test.