Moon-Young Cho

SIMULATION METHOD OF CONSTRUCTION HOIST OPERATING PLAN FOR HIGH RISE BUILDINGS CONSIDERING LIFTING HEIGHTS AND LOADS

Lifting indicates vertical transfer of construction resources. In high-rise building, efficient plan and management on lifting of resources are ess ential because of enormous impact on schedule, and amount of resources and data. In part icular, a hoist—one of main lifting equipment for workers and construction materials—may have direct influence on overall project schedule depending on its number, location and operation method. To ensure efficient construction, it is critical to have an optimal hoi st operating plan. Engineers depend on various empirical methods, which have been optimized through numerous feedbacks from construction projects. Therefore, it is necessary t o optimize hoist plan and management based on both engineers’ experiences and simulation based on actual data on lifting load and height. This paper describes a simulation method to provide data to an experienced engineer for accurate decision-making.

An Algorithm for Hoisting Time Calculation in Super-tall Building Construction

An installation of the construction lift has a few limitations by many constrains and these have influences on labor productivity, that can be changed by vertical-transportation management. In the super-tall building construction, a management of construction lift operation is one of the most important factor, but existing methodologies depend on skilled practitioners` experiences. And it is true that the expertise resulted by the experiences does not transfer to the next generation. This study is a part of lifting-management simulation development which aims at the optimal construction lift management. A proposed algorithm is focus on lifting time calculation considering an acceleration capability. This research evaluates the result accuracy using comparative analysis on simulation result and field measuring time.

WIRELESS VIBRATION SENSOR FOR TUNNEL CONSTRUCTION

During and after tunnel construction, many problems including civil petitions and construction delay result from tunnel deformation, ground settlement, ground vibration, and tunnel lining crack. In relation to tunnel construction and maintenance, this study explains a development background of small wireless vibration sensors and their applications based on RF(Radio Frequency)-MEMS (Micro Electro Mechanical System) technology. The advantages and usefulness of the wireless automatic monitoring system is addressed compared with the conventional wired or survey measurement systems. Thus, the study provides a framework of the process for monitoring, manipulating, and transferring data from MEMS sensor and explains the application of the new developed automatic monitoring system for tunnel construction and maintenance.

Test-bed Development for Long-term Monitoring of Small Bridge Asset Management

While Category 1 and Category 2 bridges are intensively inspected and carefully managed, many small bridges that are not in the Category 1 and 2 are often forgotten until they decay in serious condition. Since many of these small bridges located in the populated city, failure of them would cause huge negative impact on the community. This paper focuses on the small size concrete bridges for timely repair and rehabilitation work for the effective operation and management. Test bed is developed to define the key parameters to forecast the long term performance of the bridges, mostly concrete box bridges. Key parameters suggested in this paper are cumulative fatigue due to repetitive heavy traffic loads and the acid attacks for concrete material deterioration. The cumulative fatigue is measured by the use of the mileage concept. For the long term data collection and inspection, stable and easy to use data collection system is installed as a test bed. The contribution of this research work is on the development of the test bed to define the key parameters of bridge deterioration.

MERGING POINT CLOUDS FROM HETEROGENEOUS 3D SCANNERS FOR FAST UPDATE OF AN EARTHWORK SITE MODEL

In earthwork sites, its terrain shapes are changing continuously as the work proceeds. If someone wants to grab three-dimensional geometry data of such sites, currently available technologies such as 3D laser scanners are unable to collect reasonably precise data in pseudo-real time (i.e., 1-10 scans per second). To tackle the problem, the authors took ‘dual scanners’ approach, where low-speed (yet highly-precise) laser scanners are used for initial scan of the work site, then augment the initial data using the 3D geometry data collected from excavator-mounted stereovision. For this approach, the authors used ICP (Iterative ClosestPoint)-based algorithms for merging the stereovision data with the laser scan data, where similarities of both data are limited due to changed site shape.

Development of MEMS-Based Vibration Sensor for Tunnel Construction and Maintenance Monitoring System

Recently, the demand for sensor technology has increased remarkably in all industrial fields. Sensor technology is closely related to cutting-edge technologies such as semiconductor technology and minute structure building technology, and thus, the high demand for small and light devices with high performance provides the impetus for conducting studies in order to develop sensors with much better performance. In this study, we developed a MEMS-based vibration sensor for tunnel construction and maintenance monitoring system. For this, we investigated the definition and summary of MEMS technology and also analyzed the types and characteristics of MEMS processing technology and the strong points of MEMS technology. We also analyzed current research results on sensor applications based on MEMS for construction. The types of work, characteristic and frequency of tunnel measurement, and investigated the characteristics of measuring instruments for doing the pertinent works are analyzed. We manufactured the MEMS vibration sensor for tunnel construction in order to measure blast vibration and we also measured the vibration through experiments.

Model Development of the Material Tracking System for High-Rise Building Construction Project Using RFID Technology

Current study of material management on construction site insists that the ratio of material handling costs to total project costs varies in 30 to 80% depends on the type of construction and the cost of materials [1]. Site layout planning and material management are fundamental to reduce materials handling and re-handling costs and to enhance the efficiency of construction operation for high-rise building. Moreover, these are useful to control planned construction schedule by eliminating the factors related to spatial conflicts due to limited space. There is a need for tracking and controlling effectively material loading and delivery time especially during finishing-work phases to eliminate the need for laydown space on site. Hence, it is essential for monitoring of relevant information regarding material procurement in construction sites and it is the key factor for successful site control and adopting Just-in-Time concept in high-rise building construction. Eventually, the material tracking system is very important for requisition, delivery, and movement of the materials in time. In this paper, the material tracking system using RFID (Radio Frequency IDentification) technique is introduced. Using this system, the materials are going to be efficiently tracked and managed in finishing-work phases.

Effect of Hole Pitch Ratio and Compound Angle on the Thermal Flow Fields of Double-Jet Film Cooling Hole

In this study, the effect of a row of double-jet film-cooling hole configurations on the thermal-flow characteristics of gas turbine blades was examined. To investigate the effect of the interference of anti-kidney vortices, the ratios of the pitch distance and hole diameter (P/d=5, 6.25, 8.333) were considered with two different compound angles (λ=0°, 4°). The film cooling performance and the generated losses were studied. Then, the relevant mechanisms were identified and explained. A numerical study was performed using ANSYS CFX 14.5 with the shear stress transport (SST) turbulent model. The blowing ratio was kept at a constant value of M=1.5. The film cooling effectiveness and temperature distribution are graphically depicted with various geometrical configurations.Copyright

A Development of 3D Image Data Merging Module for Intelligent Excavation System

This research is a part of Intelligent Excavation System (IES) Development Project which aims the autonomous excavator for earthwork. The developed module focuses on measuring real-time productivity for Task Planning System(TPS) of the IES. This module merges 3D data obtained using two different 3D imaging systems : The 3D laser scanner ; and the stereo vision system. Real-time productivity of IES is calculated automatically. Once point cloud data is acquired by the 3D scanner, it is converted into mesh surface. Some post processing such as mesh optimization (reduce slenderness) and noise filtering are performed. Point cloud data is also acquired by the stereo vision, which is installed on the top of the cabin of the IES. Teo different 3D surface data are merged by the automatic fitting and smoothing algorithm. Excavated earth volume changes are recognized during the merging process. This research evaluates the performance of the merging algorithm using the real data from the civil earthwork site.

An Optimatl Algorithm of The Multi-Lifting Operation for Super-Tall Building

The operation and management plan for a lift, an important factor determining work productivity on a highrise building construction site, has long been considered to be less significant than those for a tower crane, which has resulted in a lack of studies of systematic operation planning for lift. Due to various restrictions on high-rise construction sites, only a small number of lifts can be installed. The restrictions on the installation of lifts have a great influence on labor productivity by floor, which can be changed by the management of the vertical movement of the lifts. Improving the work efficiency of lifts at a construction site is evaluated as an essential management factor to improve labor efficiency on each floor; on the other hand, the efficient management of such lifts is dependent on experienced workers. Considering this, as part of a simulation development for the work efficiency of lifts, one of the major factors in a high-rise building construction, this research aims to develop an algorithm to predict and operate the optimal lift operation time, when two or more lifts are simultaneously operated, based on the work efficiency time calculation algorithm, and to present the optimal operation expectation of the lift in a quantitative way. In the future, the algorithm developed in this research will be equipped in a module to predict and evaluate the work efficiency of a lift in an intelligent work efficiency management system.