• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.95-103
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• 1996

This paper describes a computer aided design system for spur and helical gears. To establish the appropriate program, an integrate approach based on a rule-base system was adopted. This system is implemented on the personal computer and its environment is a commercial CAD package called AutoCAD. This system includes a main program and five sub-modules such as data input module, tooth profile drawing module, strength calculation module, and drawing edit module. In the main program, all the sub-modules are loaded and the type of gear and tooth profile are selected. In the data input module, the variables which are necessary to the design of gear are selected from the database. In the drawing module, from the calculated results, the required gear tooth is produced on the screen. The developed system that aids gear designer provides powerful capabilities for gear design.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.14-15
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• 2021

Recently, the size of tiles used for bathroom walls in apartment houses is gradually increasing in size. The problem is that when these large-sized tiles are attached by the sticking method, due to the nature of the method, there is a concern about the stability of the attachment to the part (pupil) where the tile and the adhesive are not attached. The problem is serious as it leads to lawsuits in the outbreak court. In addition, it is urgent to verify the adhesion stability of the sticking method because secondary damage occurs due to a safety accident caused by the falling of the tile. Ministry of Land, Infrastructure and Transport [Investigation of defects in apartment houses, calculation of repair cost and defect determination criteria] ① The tile adhesion strength is 0.39N/mm² or more and ② It is specified to fill 80% or more of the base area of the tile backside, but this is currently trendy. It is considered that large-sized tiles need to be verified from multiple angles, and as part of that, we intend to verify the adhesion stability according to the area to be attached to large-sized tiles.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.57-58
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• 2022

Concrete mix design is used as essential data for the quality of concrete, analysis of structures, and stable use of sustainable structures. However, since most of the formulation design is established based on the experience of experts, there is a lack of data to base it on. are suffering Accordingly, in this study, the purpose of this study is to build a predictive model to use the concrete mixing factor as basic data for calculation using the DNN technique. As for the data set for DNN model learning, OPC and ternary concrete data were collected according to the presence or absence of admixture, respectively, and the model was separated for OPC and ternary concrete, and training was carried out. In addition, by varying the number of hidden layers of the DNN model, the prediction performance was evaluated according to the model structure. The higher the number of hidden layers in the model, the higher the predictive performance for the prediction of the mixing elements except for the compressive strength factor set as the output value, and the ternary concrete model showed higher performance than the OPC. This is expected because the data set used when training the model also affected the training.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2092-2098
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• 2024

Probabilistic safety assessment (PSA) plays a critical role in ensuring the safe operation of nuclear power plants. In PSA, event trees are developed to identify accident sequences that could lead to core damage. These event trees are then transformed into a core-damage fault tree, wherein the accident sequences are represented by usual and complemented logic gates representing failed and successful operations of safety systems, respectively. The core damage frequency (CDF) is estimated by calculating the minimal cut sets (MCSs) of the core-damage fault tree. Delete-term approximation (DTA) is commonly employed to approximately solve MCSs representing accident sequence logics from noncoherent core-damage fault trees. However, DTA can lead to an overestimation of CDF, particularly when fault trees contain many nonrare events. To address this issue, the present study introduces a new zero-suppressed ternary decision diagram (ZTDD) algorithm that averts the CDF overestimation caused by DTA. This ZTDD algorithm can optionally calculate MCSs with DTA or prime implicants (PIs) without any approximation from the core-damage fault tree. By calculating PIs, accurate CDF can be calculated. The present study provides a comprehensive explanation of the ZTDD structure, formula of the ZTDD algorithm, ZTDD minimization, probability calculation from ZTDD, strength of the ZTDD algorithm, and ZTDD application results. Results reveal that the ZTDD algorithm is a powerful tool that can quickly and accurately calculate CDF and drastically improve the safety of nuclear power plants.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.413-420
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• 2011

The test results of high-strength concrete beam specimens, which have various combinations of different types of flexural reinforcement and short fibers, were compared with the prediction results of codes, guidelines and models proposed by researchers. The theoretical calculation based on the ultimate strength method of the KCI and ACI Code underestimated the ultimate moments of FRP bar-reinforced beams without fibers. The models proposed by ACI 544.4R and Campione predicted the ultimate moment capacities inaccurately for the FRP bar-reinforced beam with steel fibers, because these models do not consider the increased ultimate compressive strain of fiber reinforced concrete. Bischoff's deflection model predicted the service load deflections reasonably well, while the deflection model of ACI Committee 440 underestimated the deflection of FRP bar-reinforced beams. Because the ACI 440 expression, used to predict member deflection, cannot directly apply to the beams reinforced with different types of reinforcing bars, an alternative method to estimate the deflections of beams with different types of reinforcing bars using the ACI 440 expression was proposed. In addition, Bischoff's approach for computing deflection was extended to include deflection after yielding of the steel reinforcement in the beams reinforced with steel and FRP bars simultaneously.

• Journal of the Korea Institute of Building Construction
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• v.19 no.6
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• pp.539-547
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• 2019

Recently, the international community signed a climate change agreement to prevent global warming. Yet currently, the fossil fuels have been widely used in to supply building energy for cooling and heating. The Green Building certification (G-SEED), an energy efficiency rating for new or existing buildings requires that buildings meet certain conditions. Insulation is used as a building material to reduce the energy supply to buildings and to improve the thermal insulation, and it accounts for more than 90% of the total heat resistance provided by the building surface components that meet the energy-saving design standards of new buildings. In this investigation, a performance evaluation study was conducted through an experimental study by directly extracting the foam polystyrene insulation on-site during the remodeling of a building that was in the range of 22~38 years old. Through tests, it was found that the thermal conductivity of the extrusion method insulation (XPS) was reduced by 48% and the compressive strength of XPS decreased by 36% compared to KS M 3808, which is the initial quality standard. For bead method insulation (EPS) with a thickness of 50mm, the thermal conductivity, the compressive strength, and flexural failure load were similar to the initial quality standard. Therefore, in the calculation of the primary energy requirement per unit area per year, the performance of bead method insulation can be estimated simply by considering the thickness of the insulation, while a correction factor that considers its performance deterioration should be applied when extrusion method insulation is used.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.573-581
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• 2008

In general, conventional sheeting H-pile is often used as a temporary member installed upon construction of outer retaining wall at basement floor. In CBW (composite basement wall), R/C basement wall is combined with H-Pile and resists lateral soil pressure together. This paper presents an experimental results of push out shear test of CBW with stud coupler as shear connectors to combine H-Pile with R/C wall six specimens with different diameter of FT (form tie) and arrangement of shear connectors were tested to evaluate the shear capacity of the composite wall. Test results showed that shear strength increased with diameter of FT. The shear strength of shear connector in CBW could be suitably predicted by using the previous equations codified in the codes. Best correlation, especially, was found when the calculation result by the formula in AISC 360-05 was compared to test one.

• Journal of Korean Society of Steel Construction
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• v.25 no.6
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• pp.601-612
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• 2013

In the present study, details of the TSC beam-to-PSRC column connection for low and middle seismic zones were developed. For ease construction, the top and bottom flanges of the steel section of the TSC beam were discontinuous at the joint face on purpose, while the web passes through the joint. Thus, tensile resistance of the top and bottom flanges is not considered in the calculation of nominal strength of the connection. Cyclic loading tests on two interior connections and an exterior connection were performed to verify the seismic performance. The test parameter for two interior connections was the depth of the TSC beams: 600 and 700 mm including the slab depth. The test results showed that the nominal strength of the connections predicted by KBC 2009 correlated well with the test results. The connection specimens exhibited relatively good deformation and energy dissipation capacities, greater than the requirements for the ordinary and intermediate moment frames. Ultimately, the connection specimens were failed at the story drift ratios of 3.0 to 4.0 % due to local buckling and tensile fracture of the web of the TSC beam passing through the joint. By modifying the existing provisions of ASCE, the joint shear strength of the TSC beam-PSRC column connection was evaluated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.531-542
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• 2017

The structural safety of small craft, such as steel ships and FRP ships, can be estimated using the measurement test of the hull plate thickness or the longitudinal bending strength test. A polyethylene boat is made using inexpensive HDPE and can be mass produced. The structural safety of a polyethylene boat cannot be guaranteed because a polyethylene boat hull is notspecified in the KR technical rules. The inspection procedure of sailing yachts and pleasure boats and drop test method of ISO standard 12215-5 propose the structural strength required for small crafts as the drop test height. Therefore, in this study, the drop test of a polyethylene boat hull was carried out based on the inspection procedure of a sailing yacht and pleasure boat and the drop test method of ISO standard 12215-5. The drop load was acquired by the drop acceleration ofa boat hull. Structural analysis and safety of a polyethylene boat were performed by the drop load and allowable stress criteria. The calculation results of the hull plate thickness by structural design specification of ISO standard 12215-5 showed that polyethylene boat hull was more than two times thicker than a steel ship hull and the boat hull determined by the inspection procedure of sailing yacht and pleasure boat and drop test method of ISO standard 12215-5 was more than 1.2 times thicker than the boat hull determined by structural design specification of ISO standard 12215-5. Therefore, inspection procedure of sailing yachts and pleasure boats and drop test method of ISO standard 12215-5 was much more conservative than the structural design specification of ISO standard 12215-5 and could be used as the structural design method of a polyethylene boat.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.489-496
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• 2016

Recently, a concern about hollow core precast concrete (PC) slab has been increased as a method to improve the construction ability by reducing the self weight of structures during the construction. Hollow core slab which is known as a typical PC slab in domestic construction of PC building has a problem to put shear reinforcements in the web of element during the production of element in the factory. With regard to this point, recently, tripple ribs slab (TRS) which can be said as a new type of half PC slab system was developed. In TRS, it is possible to place shear reinforcements in PC element during the production of the element in the factory. This paper presents the shear test result of TRS which was done by one point loading test under simple support condition. Test parameters are the presence of cast-in-place (CIP) concrete and the contribution of lattice bars. From the test, it was found that the TRS has sufficient shear capacity to resist the design load and its strength can be predicted by the code equations for general beam. It is recommended to ignore the strength of lattice bar in the calculation of shear strength during the construction since its contribution is too low to be considered when CIP is not casted.