Kyung In Kang

Application of AdaBoost to the Retaining Wall Method Selection in Construction

The appropriate selection of construction methods is a critical factor in the successful completion of any construction project. Artificial intelligence techniques are widely used to assist in the selection of a construction method. This paper proposes the use of the adaptive boosting (AdaBoost) model to select an appropriate retaining wall method suitable for particular construction site conditions, in order to examine the applicability of AdaBoost in construction method selection. To verify its applicability, the proposed model was compared with a support vector machine (SVM) model, which have been attracting attention for their high performance in various classification problems. The AdaBoost model showed a slightly more accurate result than the SVM model in the selection of retaining wall methods, demonstrating that AdaBoost has advantages (e.g., robustness against defective data with missing values) in application to decision support systems. Moreover, the AdaBoost model can be used in future projects to assist engineers in determining the appropriate construction method, such as a retaining wall method, at an early stage of the project.

Comparing Cost Prediction Methods for Apartment Housing Projects: CBR versus ANN

Abstract Prediction of the cost estimation of apartment house is an important task in the management of construction projects. This study aims at illustrating the compared results of the application of two different approaches which are used case-based reasoning (CBR) and artificial neural networks (ANN) techniques. This study is conducted by using the same 540 cases which are obtained in Korea. 30 cases among the data are used for testing. Testing error rates of 3.69% in the CBR and 6.52% in the ANN were obtained. Results showed that CBR can produce slightly more accurate results and achieve higher computational efficiency than ANN. If the use of CBR and ANN is understood better, as a result, cost estimation can be predicted with reasonability, all parties involved in the construction process could save considerable money.

Automated Lifting System Integrated with Construction Hoists for Table Formwork in Tall Buildings

AbstractIn tall-building construction, the equipment-driven table formwork method is a useful alternative for improving productivity of horizontal formwork with less skilled labor. The lifting system significantly affects the productivity and costs of table formwork operation. This study proposes a new system integrated with the construction hoists for automating the lifting process of table formwork. The system targets crane-independent transportation for productivity improvements while overcoming the limitations of the existing independent lifting system, which include high initial cost and extra work for assembly and operation. In a case study, the proposed system showed 49.4% improved productivity over a tower crane, and equipment costs were 73.8% lower than those of the existing independent system. The simplified structure of the system through integration with the hoist could minimize the additional time and cost inputs for its assembly and operation. The proposed system could provide more flexible ...

Evaluating work space environment in a construction factory for automated construction

The erection of a structural steel frame in high-rise construction requires a significant amount of skilled labor and is inherently a very dangerous occupation. In order to resolve these problems, the use of robots in structural steel frame erection is currently being researched in Korea. In addition, since robots consist of many sensitive machines, sensors, and devices, the development of a weather-unaffected working space was considered. However, the advanced automation construction systems being developed in Korea differ from those previously researched in that the former employ existing tower cranes; therefore, the need for a construction factory (CF) that comprises a temporary shield with opening and shutting sliders was felt. Therefore, the work space environment, which is covered by a CF, should be evaluated to enhance the advanced automation construction systems in Korea. The objective of this study is to evaluate the work space environment in CF by using a simulation method such as computational fluid dynamics. The results of this study reveal that a CF can provide a work space with a suitable and stable environment for construction automation, thereby enabling the development of advanced automation construction systems in Korea.

Analysis of a steel frame fabrication process for the automation of building construction

The construction industry has lower levels of improvements in technology and productivity than any other industry. One of the most useful tools to change this state of affairs is construction automation. Steel frame fabrication is a major activity in building construction, but it is difficult to employ skilled labor, as the work is hard, dangerous, and specialized. Currently, there is pressure to develop an automation system for steel frame fabrication, and this should be based on a detailed motion study to determine the required function and degree of freedom. We have developed a work breakdown structure (WBS) and modified the therblig symbol system to analyze in detail the unit motions of steel fabrication. We evaluated each motion using therblig and an analytic hierarchy process from the viewpoints of specialization, difficulty, and danger, and evaluated the overriding motion requiring automation. We propose a concept design for an automation system for steel frame fabrication that will be very helpful in automating steel frame fabrication.

Development of a hybrid device based on infrared and ultrasonic sensors for human resource management

Human resources are continuously gaining importance in association with construction site management. With increasing interest being shown in the use of state-of-the-art technologies such as radio frequency identification (RFID) in site management, we developed a device based on infrared radiation and ultrasonic sensors for application in the management of human resources, especially labour safety management. We tested sensors and optimized the sensing range and angle of the device, which could detect workers using an infrared sensor that senses body heat and an ultrasonic sensor to measure the object’s distance. The device allows a manager to determine where workers are, and how far they are from the point of sensing. This paper shows that the device can prevent fatal accidents such as falls. In doing so, it addresses a key issue in the management of safety on work sites.

Simulation-based Planning Model for Table Formwork Operation in Tall Building Construction

Operation planning for table formwork using a crane-independent lifting system (CLS) is a crucial factor affecting productivity for formwork in tall building construction. Inappropriate heuristic operation plans are likely to increase work duration because of temporarily displaced stacks of table forms, and may also increase costs because of excessive use of equipment. The authors propose a simulation-based operation planning model for table formwork for efficient operations in tall building construction. By optimizing the shifting sequence of table forms and the location of the CLS in a case study, the proposed model reduced working hours for table forms by 6.62% from the working hours derived by a heuristic approach. Furthermore, the derived alternatives reduced working hours by a maximum of 45%, depending on the number of trolleys used. This study can be utilized for informed decision-making by construction workers in tall building construction while selecting the optimal operation plan for table forms by considering project cost and schedule.

Inhibiting Factors and Improvement Plan of Table Formwork Method in High-Rise Building Construction

The table formwork method for high-rise building formwork can shorten the construction time and reduce manpower through machineand equipmentbased automation. However, this method is not used as much as other system formworks. Various studies have been conducted to activate the table formwork method; but, the problems in associated with the automation work of table formwork are not understood, because researchers are focusing on improving efficiency through new technology development. As a basic study of the activation of the table formwork method, this study proposes an improvement plan after analysing the problems and satisfaction level according to the detailed process of the table formwork method. The results of this study are expected to expedite the process improvement and activation of the table formwork method.

Case Study of the Core Structure Succeeding Method for Tall Building Construction

AbstractIn tall building construction, the adoption of the appropriate construction method for the core structure process is critical in terms of both the structural aspect of the building and the schedule estimation. This study introduces a new core structure succeeding construction method (CSSCM) for tall buildings with steel-reinforced concrete structures to address the obstacles of the existing core structure preceding construction method (CSPCM) such as limited workspace, interference between activities, difficulties in wall and slab joint construction, and similar obstacles. The study also shows the technical details and compares the results from the applications of CSPCM and CSSCM to an actual tall building project. The results revealed that this method has potential as a cost-effective construction method for structural frameworks of tall buildings where short cycle times are required. In addition, the method provided stable working environments for the steel erection including outriggers and core...

A Preliminary Study for Dynamic Construction Site Layout Planning Using Harmony Search Algorithm

Construction site layout planning is a dynamic multi-objective optimization problem since there are various temporary facilities (TFs) employed in the different construction phase. This paper proposes the use of harmony search algorithm (HSA) to solve the problem that assigning TFs to inside of the building. The suggested algorithm shows a rapid convergence to an optimal solution in a short time. In addition, comparative analysis with Genetic Algorithm (GA) is conducted to prove the efficiency of the proposed algorithm quantitatively.