• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.29-32
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• 2009

Building foundations for Top-Down construction require a special setting, because the foundations have to be placed way before excavation for the substructure of main building, Usually, the foundation goes into the layer of rock and it is often called rock-pier foundation, Currently, a cage of steel reinforcing bars is inserted to the pre-excavated hole in the rock layer, hanging down from the wide flange steel column above. This paper presents a new method for connecting the prefounded column and the steel cage with a coupler for better connection between the two, The use of a circular Concrete Filled Tube (CFT) as a prefounded column makes it possible to have this type of connection. The details of the connection and application to a Top-Down construction site is also included in this paper.

• Korean Journal of Computational Design and Engineering
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• v.7 no.1
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• pp.42-56
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• 2002

Presented in this study is a top-down functional requirement analysis procedure and the desired functionalities for PDM system development, and the benefits of top-down approach over a conventional bottom-up approach is also shown. For the purpose of top-down requirement analysis for PDM system, this study proposes 4P modeling view. 4P modeling view is defined as a modeling perspective for classifying functional requirements and integrating product-related information objects that must be man-aged within PDM systems. Based on 4P modeling templates, benchmarking analysis of commercially major PDM products is conducted and as a result of this analysis, this study suggests desired functionalities for PDM system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.25-30
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• 2011

Almost prefounded columns for top-down construction certainly have construction tolerances in plan and plumbness. Therefore, it is very difficult to connect prefabricated beams to prefounded columns at each floor level after excavation by usual top-down connection method and this usual connection method leads to long construction time, increasing cost and decreasing quality. This paper presents a new method for connecting prefabricated beam to prefounded column with GROUT-JACKET CONNECTION SYSTEM consisting of sleeve, bearing-shear bands and grout. Details and illustrations of the connections and applications by GROUT-JACKET CONNECTION SYSTEM for the top-down construction are also included in this paper.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.27-30
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• 2008

For the purpose of developing economical and time-efficient formwork for Top-down construction, a Non-Supporting Form System has been proposed. The system is consisted of two parts: a hanging part to support a steel frame and a section of concrete slab, and the other hanging part to lower the steel frame. In this paper, the proposed system is compared to two existing systems of Non Supporting Top-down Method and Bracket Supported R/C Downward Method. It is expected that this system can be used in Top-down construction with further development.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.788-793
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• 2009

Constructing substructures by using Top-Down or Downward method needs an efficient formwork system because of difficulties in supporting concrete slabs from the bottom while excavation is in process. Existing underground formwork systems can be classified by three types: graded ground supported type (Slab On Grade, Beam On Grade), suspension type (Non Supporting Top Down Method), and bracket supported type (Bracket Supported R/C Downward). Each method has its own advantages and limits. Application of a specific formwork system for a given construction site is determined by various conditions and affect construction time and cost. This paper presents a newly developed underground non-supporting formwork system, which combines the advantages of a suspension type and a bracket supported type while it overcomes limits of two types. The developed system has a moving formwork which is supported by suspension cables hanging from the bracket placed at the top of pre-installed substructure columns. Then, the moving formwork is repeatedly lowered down for the next floor below to support concrete slab during curing. The details of this bracket and cable supported system have been investigated for the improvement of easiness in construction.

• Journal of the Korean Society of Systems Engineering
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• v.9 no.2
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• pp.69-82
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• 2013

US DoD operated JCIDS(Joint Capability Integration and Development System) for top down requirement generation. Although the JCIDS can be a good practice for the countries which are trying to shift from bottom up to top down requirement generation, it contains many processes related with review and approval. In this study we structured a joint capability integration and development process from the JCIDS eliminating the organization dependent review or approval process so that it can be applied to any organization with some modification. Furthermore we implemented the process in the computer aided systems engineering tool, Cradle, for convenient use of the process. The result of this study can provide a basic process for top down capability development, and an efficient why of doing each element of the process using CASE tool.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.48-53
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• 1998

The purpose of this study to fine the mixture of concrete for Top-Down method. As a result, In fresh concrete, slump value and slump-flow value were increased as fly ash concrete(10% ratio). When plasticizer was added 1.5% by weigh of binder in concrete, no fly ash concrete and fly ash concrete(10% ratio) all occurred segregation. And, no fly ash concrete and fly concrete(10% ratio) all showed compressive strength development close plain concrete as increasing plasticizer quantity. Especially, in case of 1.5% plasticizer of binder showed high compressive strength development.

• Journal of Korean Society of Rural Planning
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• v.21 no.3
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• pp.67-84
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• 2015

Although the bottom-up rural area development project was conceived with great expectations, the general evaluation of the project so far reveals that it does not significantly differ from projects carried out in a top-down manner. This paper examines the nature of the bottom-up rural area development project with a focus on its background, including the roles of authority and project participants. Results revealed that the project was designed to be implemented in line with the state affairs ideology of the leader in a negative position of bureaucratic society. Though the form of implementation for the project seemed bottom-up as seen in the process of the roles and authorities in supporting organizations the top-down method of implementation can be seen in the authorities and roles of the central government. It was also noticed that the private sector, designed to elicit participation of various experts, looked to be managed and controlled by public organizations. The abovementioned signifies that the Korea rural area development project has been implemented not in a bottom-up manner but rather in an ever-strong top-down manner, which means that the central government holds more responsibility for the project's results, evaluation, and discussions. Furthermore, as seen in the background of the project, policies have been implemented in a top-down manner without the confidence of the bureaucratic society. Therefore, in order to implement a proper bottom-up rural area development project, there is a need for the bureaucratic society to have confidence in the rural societies.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.13-27
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• 1997

In the modern design technology, a component should be designed to fit into the overall system performance. A design methodology is developed to expedite the mechan- ical design of complex mechanical systems, The relation between the system design and component design is defined by a top-down approach and the results from the system design are utilized in the component design process. As a design example, an automobile exhaust system is selected for the system design and a bellows is chosen for a component design. Design methodology based on the top-down approach consists of five steps; (1) Analysis of service load, (2) Development of a lumped parameter, (3) Completion of the system design, (4) Selection of the component topology, (5) Completion of the component design, A method using a equivalent matrix is developed in order to determine unknown external forces in linear structural analyses. The bellows is also analyzed by the finite element method using a conical frustum shell element. Various experiments are performed to verify the developed theories. The top-down desi- gn approach is demonstrated by a design case using structural and shape optimization technology. Since the method is relatively simple and easy compared to other methods, it can be applied to the general design where system and component designs are involves simultaneously.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.129-133
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• 2008

For the construction of Top-Down structures, it is crucial to have a solid connection between prefounded columns and slabs. This paper presents a new construction method for the connection when using a circular Concrete Filled Tube (CFT) as a prefounded column as an alternative to currently using wide flange type columns. The development of shear studded jackets along with a shear band suitable for the circular shape of the column has been made. The details and mechanism of the connection is explained together with the results of experiments which verified the structural integrity of the connection.