• Journal of Korean Association for Spatial Structures
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• v.17 no.4
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• pp.59-68
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• 2017

This paper aims at finding some lessons applicable to successful implementation of 'The 3D Printing R/D Project' through both examining the process of adopting overseas industrialized housing production technological knowhow by home builders during the 1970's~1980's period and thereafter until now the various efforts to adjust the technologies efficiently to the Korea's unique situation. Some meaningful lessons can be summarized as follows; I) Deep understanding of 3DP technological know-why along with its inheritance, II) Readjusting of R/D period and goals(cf. Global leader Winsun's 15 years experiment), III) Restructuring for more collaborative R/D B&E system among participating researchers IV) Fostering 3DP expert-engineers and technicians from the early stage, V) Clearing legal barriers in users' adopting 3DP methods necessary, VI) Development of appropriate building material besides concrete. Therefore, it is highly recommended that the above-mentioned 6 lessons positively accepted and applied to the Research Implementation Plan in due course, especially by KICT consortium and KAIA under the guidance of Ministry of Land, Infrastructure and Transport.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.175-184
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• 2011

To take advantage of reduced on-site construction periods and minimize traffic impacts various types of steel grid composite deck have been developed since 1930's. Modular prefabricated unfilled grid decks permit a long-distance transportation and construction under unfavorable condition, for example, in mountainous regions due to its comparatively light-weighter structure than fully filled grid deck. In this study bending tests of unfilled grid decks for the deck member of various kinds of infrastructure are carried out, bending strength and behaviour of composite action are experimentally evaluated. In this bending test, design variables are considered, such as type of shear connection between steel grid and concrete slab, spacing between cross bars and thickness of concrete slab. Through test results bending strength and behaviour of composite action are evaluated, reference data for proper type of shear connection and other details of the deck, such as spacing between cross bars, are obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.3
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• pp.613-623
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• 2011

In this paper, we present a method on the construction of quinternary logic circuits using Perfect shuffle. First, we discussed the input-output interconnection of quinternary logic function using Perfect Shuffle techniques and Kronecker product, and designed the basic cells of performing the transform matrix and the reverse transform matrix of quinternary Reed-Muller expansions(QRME) using addition circuit and multiplication circuit of GF(5). Using these basic cells and the input-output interconnection technique based on Perfect Shuffle and Kronecker product, we implemented the quinternary logic circuit based on QRME. The proposed design method of QRME is simple and very efficient to reduce addition circuits and multiplication circuits as compared with other methods for same logic function because of using matrix transform based on modular structures. The proposed design method of quinternary logic circuits is simple and regular for wire routing and possess the properties of concurrency and modularity of array.

• Steel and Composite Structures
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• v.22 no.3
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• pp.537-565
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• 2016

Australian railway networks possess a large amount of aging timber components and need to replace them in excess of 280 thousands $m^3$ per year. The relatively high turnover of timber sleepers (crossties in a plain track), bearers (skeleton ties in a turnout), and transoms (bridge cross beams) is responsible for producing greenhouse gas emissions 6 times greater than an equivalent reinforced concrete counterparts. This paper presents an innovative solution for the replacement of aging timber transoms installed on existing railway bridges along with the incorporation of a continuous walkway platform, which is proven to provide environmental, safety and financial benefits. Recent developments for alternative composite materials to replace timber components in railway infrastructure construction and maintenance demonstrate some compatibility issues with track stiffness as well as structural and geometrical track systems. Structural concrete are generally used for new railway bridges where the comparatively thicker and heavier fixed slab track systems can be accommodated. This study firstly demonstrates a novel and resilient alterative by incorporating steel-concrete composite slab theory and combines the capabilities of being precast and modulated, in order to reduce the depth, weight and required installation time relative to conventional concrete direct-fixation track slab systems. Clear benefits of the new steel-concrete composites are the maintainability and constructability, especially for existing railway bridges (or brown fields). Critical considerations in the design and finite element modelling for performance benchmarking of composite structures and their failure modes are highlighted in this paper, altogether with risks, compatibilities and compliances.

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.202-206
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• 2013

A submerged floating railway is an innovative tunnel infrastructure passing through the deep sea independent of wave and wind so that high speed trains can run on it. It doesn't depend on water depth and is cost effective due to modular construction on land. The construction period can be reduced drastically. This paper introduces the concept design of a submerged floating railway, and for securing safety, proposes a method to analyze the structural behavior of the body in case of collision with a submarine. The theory of a beam with an elastic foundation was used to calculate the equivalent mass of the body so that the perfect elastic collision could be applied to calculate the collision velocity. The maximum deformation and bending moment was analyzed based on energy conservation. To verify the results, a collision analysis using a finite element analysis code was made. Comparing the results confirmed that this simplified collision analysis method gives enough accurate deformation and bending moment to be used for actual estimation in the initial design stage.

• Korean Journal of Construction Engineering and Management
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• v.24 no.2
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• pp.37-49
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• 2023

In this study, we proposed resource allocation methodologies to improve the productivity of steel bridge manufacturing plants based on the constraint theory which is very popular in the area of manufacturing industries. To this end, after defining the painting process as a bottleneck, three resource allocation methodologies were developed: Operation Specific Resource Allocation (OSRA), Product Specific Resource Allocation (PSRA), and General Resource Allocation (GRA). As a result of experiments for performance evaluation using a simulation model of the steel bridge supply chain, GRA showed the best performance in terms of the Number of Work-In-Process (NWIP) and Waiting Time (WT), in particular, as workload itself and its variability were increased, the performance gap with the specific resource allocation became further deepened. On average, GRA reduced NWIP by 36.2% and WT by 34.6% compared to OSRA, and reduced NWIP by 71.0% and WT by 70.4% compared to PSRA. The reduction of NWIP and WT means alleviating the bottleneck of the painting process, which eventually means that the productivity of the steel bridge manufacturing plant has improved.

• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.3-11
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• 2016

The concern about hollow core PC slab has been increased to improve the workability during a construction of building by reducing self weight of structural members. In this manner, recently, TRS (Tripple Ribs Slab) was developed as a new type of half PC slab system. TRS member consists of the triple webs and the bottom flange prestressed by strands. The slab system is completed by casting of topping concrete on the TRS after filling styrofoam between the webs. This paper, presents a flexural experiment to investigate the flexural capacity of the TRS. Five full scale TRS members were made and tested under simple support condition to be failed by flexure and their strength was evaluated by code equations; the variables in the test are the depth and the presence of topping or raised spot formed when slip-forming. In addition, a nonlinear sectional analysis was performed for the specimens and the result was compared with the test results. From the study, it was found that the TRS has enough flexural strength and ductility to resist the design loads and its strength can be suitably predicted by using code equations. The raised spot did not affect the strength so that the spot need not to be removed by doing additional work. For the more accurate prediction of TRS's flexural behavior by using nonlinear sectional analysis, it is recommended to consider the concrete's brittle property due to slip-forming process in the modeling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.447-455
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• 2019

When constructing LNG storage structures using the cast-in-place method in extreme areas, the construction cost and time may be increased due to the poor working environments and conditions. Therefore, demand for modular energy storage tanks is increasing. In this study, we propose using an SCP module as an alternative for lighter-weight LNG storage tanks. The purpose of this study is to evaluate the feasibility of LNG storage outer tanks by performing bending tests on the thickness of composite steel plate concrete under field conditions. The loads on specimens with thicknesses of 100 mm and 200 mm were linearly increased to the design final loads of 413 kN and 822 kN, respectively. The slope was rapidly changed, and fracture occurred. The two test conditions showed linear behavior until the steel plate yielded, and after an extreme load behavior, sudden yielding of the steel plate yield occurred in the SCP bending test according to the INCA guidelines. The results satisfied the design flexural load and showed the possibility of using the specimens in a modular LNG outer tank. However, it is necessary to evaluate the structural performance of the SCP by performing compression and shear tests in future research.

• Smart Media Journal
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• v.12 no.5
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• pp.36-45
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• 2023

Recently, in digital agriculture, the types and utilization of greenhouses based on IoT are spreading, and greenhouses are being modernized, enlarged, and even factoryized using smart technology. However, a specific standardization plan has not been proposed according to the equipment for data collection in the smart greenhouse and the size or shape of the greenhouse. In other words, there is a lack of standard data for facility equipment, such as the type and number of sensors and equipment according to the size of the greenhouse, the type of greenhouse construction film and materials suitable for crops and carbon neutrality. Therefore, in this study, the suitability of the implementation, installation and quantity of IoT equipment for data collection was tested, and some standard technologies were presented through the implementation of data collection and communication methods. In addition, impact strength, tensile, tear, elongation, light transmittance, and lifespan issues for PE, PVC, and EVA, which account for about 90% of existing greenhouses, were presented, and the shape, size, and environmental problems of greenhouses made of films were presented. presented in the text. In this research paper, a standardized carbon-neutral modular smart greenhouse using nano-material film was implemented as a solution to environmental problems such as greenhouse size, farm crop type, greenhouse lifespan, and film, and its performance with existing greenhouses was analyzed and presented. Through this, we propose a modularized greenhouse that can be expanded or reduced freely without distinction in the size of the greenhouse or the shape of farmhouse crops, and the lifespan is extended and standardized. Finally, the average characteristics of greenhouses using existing PE, PVC, and EVA films and the characteristics of greenhouses using new carbon-neutral nanomaterials are compared and reviewed, and a plan to implement an expandable IoT greenhouse that supports carbon neutrality is proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.182-189
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• 2019

3D printing technology is changing the paradigm of consumer-oriented design in supplier-oriented mass production. 3D printing technology in construction is expected to be able to replace existing wet methods along with modular construction. Recently, a number of cases of building construction using 3D printing using mortar-based materials have been announced in many regions, including North America, Europe, and Asia. In this study, we developed a design support tool with a slicing function to output 3D modeling for architecture for a 3D printing machine. We analyzed the process and the function of slicing programs that are commercially available. Seven slicing functions required for the architectural field were derived by analyzing cases, expert reviews, and related literature. The derived functions were extended from the slicing functions to develop the design support tools. Detailed algorithms and processes need to be developed for future derived functions.