Junbok Lee

Experimental study on bond strength of fiber reinforced polymer rebars in normal strength concrete

The bond behavior of reinforcing bars is an important issue in the design of reinforced concrete structures and the use of fiber reinforced polymer (FRP) rebars is a promising solution to handle the problems of steel reinforcement corrosion. This study investigates the bond characteristics of carbon and aramid FRP (CFRP and AFRP) bars embedded in normal strength concrete. A pullout test was performed on 63 normal strength concrete specimens reinforced with FRP and steel rebars with different embedment lengths and bar diameters. The average bond stress versus slip curve is plotted for all specimens and their failure modes are identified. The effects of the embedment length and diameter of an FRP rebar on its bond strength are examined in this work. The bond strengths obtained from the test results are compared with the predictions by the bond strength equation proposed by Okelo and Yuan (2005), and its validity is evaluated.

Basic Study of Smart Robotic Construction Lift For Increasing Resource Lifting Efficiency in High-Rise Building Construction

Most high-rise buildings are erected in downtown areas, where on-site storage space for construction materials is typically insufficient due to limited spaces. Just-In-Time (or JIT) concept has been adopted so that necessary stock materials and storage spaces can be reduced; for high-rise buildings, however, transporting materials vertically using lifts still poses significant efficiency because its efficiency drops exponentially as the building height grows. Most of current efforts to counter this problem mainly focus on developing smart tower cranes, whereas lift has gathered less attention in this respect. This research aims to develop a robotic lift capable of autonomous operations at night time, based on the intelligent lift development toolkit which was previously developed by the authors. It is now in a preliminary study phase. This study proposes a concept model of the robotic lift system and its operation plans, utilizing several technologies such as an optimized material dispatch algorithm and ubiquitous sensor networks (USNs). The proposed system can be relayed to the horizontal transportation robots located in each floor to move the lifted materials to their destinations. The outcome from this study will contribute to the improvement of the overall efficiency of the high-rise building construction logistics and space constraints of the construction site. It is also expected that the mechanical performance of the existing lift system can be benefited from this research. When overall system development, including optimized operation planning model and monitoring subsystem, is finished, it will contribute to innovation of the construction technology.

An Application of PDA and Barcode Technology for the Improvement of Information Management in Construction Projects

Work information in a construction project can be effectively used to analyze the project status related to schedule, cost, productivity etc. The purpose of this research is to develop a computer-based system using PDA and barcode technology to measure and monitor the amount of workforce resources and productivity. The developed system is expected to effectively assist schedule planning and management for present and prospective construction projects.

Analysis of Pre-construction Processes and Development of KMS Prototype of LNG Plant Projects

Recently, overseas construction projects have beenincreasing in the Middle East andSoutheast Asia regions. These projects require various licensesand technologies for the manufacturing and handling processes. Additionally, the efficiency of the entire process management life cycle determines the success or failure of the business. Nonetheless, there exist various risks involved in the whole life cycle process due to a lack of experience and knowledge of management techniques. The objective of this paper is to analyze the business process of a LNG plant throughout the pre-construction and procurement phases, and to identify the knowledge and information needed for the development of the KMS. The study also plans to build a comprehensive knowledge management system throughout the whole life cycle as its final objective.

Probabilistic value analysis methodology for public water supply systems

The value of a design alternative for constructed facilities is determined based on life cycle cost (LCC) and non-economic performance such as constructability and environmental impacts. Unfortunately, the level of consensus on the results of life cycle cost analysis (LCCA) is low due to the uncertainty associated with cost and timing data for construction, operation, maintenance and disposal of facilities with very long life cycles. Non-economic performance of design alternatives is also evaluated subjectively by the stakeholders of construction projects. Therefore, it is very important to properly manage the uncertainty and the variability of input data for value analysis (VA) of design alternatives. This paper presents a probabilistic VA methodology for public water supply systems. An LCC model and a cost classification structure for public water supply systems were developed to cover the initial and the follow-on cost of public water supply systems that come from the various mechanical systems and the pipeline systems of the collecting/treating/distributing facilities. The proposed VA methodology incorporates the probabilistic results of LCCA and the non-economic performance evaluation based on reliability concept for rational decision making. The model and the procedure presented in this study can greatly contribute to the value-oriented design alternative selection and the allocation of budget for public water supply system construction projects.

Development of Core Technology for Object Detection in Excavation Work Using Laser Sensor

Earthwork is very equipment-intensive task and researches related to automated excavation have been conducted. There is an issue to secure the safety for an automated excavating system. Therefore, this paper focuses on how to improve safety for semi- or fully-automated backhoe excavation. The primary objective of this research is to develop the core technology for automated object detection in excavation work. In order to satisfy the research objective, a diverse sensing technologies are inve stigated and analysed in terms of functions, durability, and reliability. The authors developed detecting algorithm for the objects using laser sensor and verified its performance by several tests. The results of this study would be the basis for developing the automated object detection system.

A Study on Asset Valuation Method in Educational Facilities Delivered by BTL

A number of BTL projects for educational facilities have been augmented because of the increase of newtown development and deflationary policy of class size for learning efficiency. As the operation and maintenance costs rapidly increase, the budget for operation and maintenance is expected to be short. Therefore the asset management maximizing asset value is required to clarify the budget plan and distribution and provide a qualitatively high service. The main objective of this research is to establish asset valuation process in educational facilities delivered by BTL project. In order to meet the research objective, the asset valuation process is established by literature reviews, expert advice, and lessons learned from the developed countries. The developed process includes depreciation by internal accounting law, the core element of valuation, and asset valuation process. The results of the research will be help to offer the qualitatively high service and explain the standard of budget plan. It will assist commencing the asset management system.

A Development of Stewart Platform Based Pipe Manipulator

The concrete pipe laying works are conducted in most of the construction sites. Several automated systems for the pipe laying works have been developed in advanced countries to improve productivity, safety, and quality, and to gain potential savings in costs. They mainly focused upon easy handling and clamping system for the pipes. The major objective of this research is to develop the stewart platform based teleoperated pipe manipulator prototype and to evaluate technical feasibility and productivity analysis of the system.

Application of Metadata System for Efficient Information Management in Logistics of LNG plant

Abstract : Many research efforts have made on various fields to develop a system which is able to process diverse data in terms of efficiency and accuracy as well as minimizing the error in data-processing. As known, it is obvious that procurement is crucial process for the plant projects due to its importance and impact on the performance. It is strongly required to develop an effective metadata system to assist optimal controlling data for the logistics discipline of procurement processes in plant projects. Therefore, the main purpose of this paper is to apply a metadata system for logistics of the plant projects. The suggested technical module is tested using sample data and evaluated its performance in terms of accuracy and running speed. The results of this research will be extended to the other processes of plant projects in order to achieve a ultimately process-based life-cycle plant project information management system. Keywords : Plant, Logistics, Work Data, Information Management, Metadata

Development of O&M Data Management System for Pipeline Project in Permafrost Area

The securing of alternative energy is essential, since the Republic of Korea (hereafter, ROK) depends on 97% of its supply from overseas. Since G20 Summit Conference of 2011, it became possible to receive natural gas from Russia for 30 years starting from 2015 with mutual cooperative agreement for the procurement of natural gas/oil and minerals. It enabled Korea to advance to pioneering regions of extreme climate. However, it lacks the experience of design and construction of pipeline projects in permafrost area until now as well as the technique for the management of enormous information, which is generated from the project. This study aims to develop engineering data breakdown structure (DBS) and information flow of pipeline projects in permafrost area. The ultimate goal of this research is to develop a hierarchical structure of engineering/construction data for efficient project management in the extreme climate region. In order to achieve the research purpose, domestic and overseas literatures on this research topic are reviewed, and the business process of the design stage of pipeline projects in permafrost area as well as the characteristics of the important items are analyzed. Additionally, the result of this study will be used to build the comprehensive information management system for the entire process.