• Journal of Korea Society of Industrial Information Systems
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• v.24 no.2
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• pp.33-40
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• 2019

Many companies have tried to develop wind power generators with a larger capacity, smaller size and lighter weight. High temperature superconducting (HTS) generators are more suitable for wind power systems because they can reduce volume and weight compared with conventional generators. However, the HTS generator has problems such as huge vacuum vessel and the difficulty of repairing the HTS field coils. These problems can be overcome through the modularization of the HTS field coil. The HTS module coil require a current leads (CLs) for deliver DC current, which causes a large heat transfer load. Therefore, CLs should be designed optimally for reducing the conduction and Joule heat loads. This paper deals with a structural design and thermal analysis of a module coil for a 750 kW-class HTS generator. The conduction and radiation heat loads of the module coils were analysed using a 3D finite element method program. As a result, the total thermal load was less than the cooling capacity of the cryo-cooler. The design results can be effectively utilized to develop a superconducting generator for wind power generation systems.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.112-119
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• 2006

This paper is concerned with the light-weight design of a center-pillar assembly for the high-speed side impact of vehicle using advanced high strength steels(AHSS). Steel industries continuously promote the ULSAB-AVC project for applying AHSS to structural parts as an alternative way to improve the crashworthiness and the fuel efficiency because it has the superior strength compared to the conventional steel. In order to simulate deformation behavior of the center-pillar assembly, a simplified center-pillar model is developed and parts of that are subdivided employing tailor-welded blanks(TWB) in order to control the deformation shape of the center-pillar assembly. The thickness of each part which constitutes the simplified model is selected as a design parameter. Factorial design is carried out aiming at the application and configuration of AHSS to simplified side-impact analysis because it needs tremendous computing time to consider all combinations of parts. In optimization of the center-pillar, S-shaped deformation is targeted to guarantee the reduction of the injury level of a driver dummy in the crash test. The objective function is constructed so as to minimize the weight and lead to S-shape deformation mode. Optimization also includes the weight reduction comparing with the case using conventional steels. The result shows that the AHSS can be utilized effectively for minimization of the vehicle weight and induction of S-shaped deformation.

• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.91-101
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• 2004

For the grillage which is common types of structures in marine and land-based structural system, the elastic response and design methods are usually applied. However, plastic analysis and design methods are considered Tn those structures to maintain the structural stability at the limit states. In grillage design, the central intersection point load may be used as a worst loading condition. However, a point load may often move around on the grid system. in such case, the worst load point would not necessarily be at the central point. To investigate the variation of plastic collapse load according to the location of moving load between intersections, the plastic collapse loads are obtained for the three types of grillages with simply-supported ends. From the result of each case, it is confirmed that the worst load point is located between intersections. General formulae related with plastic collapse loads for the three groups of grillages with simply-supported boundaries are derived. Those plastic collapse formulae for the grillages are applied to the design of pontoon deck, and optimum design procedure is illustrated. Consequently, general formulae for the plastic collapse of grillages derived from this study can be easily applied to the plastic analysis and optimum design of similar grillages.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.107-112
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• 2008

This paper investigates the variation of post-buckling behaviours of 2-dimensional shallow arch type truss after sizing optimization. The mathematical programming technique is used to produce the optimum member size of 2D arch truss against a central point load. Total weight of structure is considered as the objective function to be minimized and the displacement occurred at loading point and member stresses of truss are used as the constraint functions. The finite difference method is used to calculate the design sensitivity of objective function with respect to design variables. The postbuckling analysis carried out by using the geometrically nonlinear finite element analysis code ISADO-GN. It is found to be that there is a huge change of post-buckling behaviour between the initial structure and optimum structure. Numerical results can be used as useful information for future research of large spatial structures.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.179-184
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• 2017

The cage of a tapered roller bearing keeps the gap between the rollers, which prevents friction, wear and suppresses heating. The material of the cage is changing from metal to plastic for lightening the weight. If the cage is severely deformed due to resonance, the roller may not be able to roll and even get off the cage. In this paper, the dynamic characteristics of the cage is analyzed according to the cage material. Under the assumption that a train runs at the highest speed, frequency harmonics of that speed is calculated, and the comparative analysis is carried out in order to select the optimum thickness of the cage, which is easy to change among the cage design variables for avoiding the resonance.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.425-432
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• 2020

The appearance of Korean traditional roof tiles is beautiful and excellent in water resistance, fire resistance and durability, but a high sintering temperature of 1,200℃ or higher is required. Therefore, due to the economical and heavy weight problem, the current trend is to use different roof finishing materials than Korean traditional roof tiles. By adding nanoaluminosilicate to clay and kaolin, which are the materials of the clay roof tiles, the sintering temperature is sintered at a low temperature of 1,000℃ or less, and the optimal mixing and material process is designed to satisfy the characteristics required as a Korean traditional roof tile. The results of this study again demonstrate the superiority of Korean traditional tiles with roof finishing materials using nanoaluminate. The properties of Korean traditional roof tiles that satisfy the criteria of KS F 3510 by applying fire resistance of natural minerals and nanoparticle technology to flexural strength of 2800N, Bulk specific gravity of 2.0g/㎤ and absorption rate of less than 10.0%, through which and researched materials development.

• Journal of the Korean GEO-environmental Society
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• v.11 no.12
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• pp.63-74
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• 2010

Normally consolidated and slightly overconsolidated soft clay layer is widely distributed in the south coast of Korea. To ensure the efficient and economical construction design of any structure to be built on this soft soil, exhaustive studies related to geotechnical and physical engineering properties are required. In this study, the relationship of the physical properties of southern Gwangyang marine clay in the Korea Peninsula were examined, including natural water content, specific gravity, total unit weight, initial void ratio, liquid limit, plastic limit, and physical properties of activity and soil parameters. For the parameter relationship analysis, the latest relatively reliable data on the large harbor construction work were used, optimum values were deducted with linear regression and non-linear regression between soil parameters, water content or initial void ratio appears to be very large. Moreover, in the linear and involution pattern regression, equal coefficient of determination appeared. The relationship of the different parameters was shown to be excellent in the non-linear regression of involution equation and exponential equation pattern compared with the findings of linear regression analysis.

• Journal of the Korean GEO-environmental Society
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• v.9 no.4
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• pp.37-45
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• 2008

Normally consolidated and slightly overconsolidated soft clay layer is widely distributed in the south coast of Korea. To ensure the efficient and economical construction design of any structure to be built on this soft soil, exhaustive studies are required related to geotechnical engineering properties. In this study, the relationship of the physical properties of southern marine clay in the Korea Peninsula were examined, including natural water content, specific gravity, total unit weight, initial void ratio, liquid limit, plastic limit, and physical properties of activity and soil parameters. For the parameter relationship analysis, the latest relatively reliable data on the large harbor construction work were used, optimum values were deducted with linear regression and non-linear regression between soil parameters, water content or initial void ratio appears to be very large. Moreover, in the linear and involution pattern regression, equal coefficient of determination appeared. The relationship of the different parameters was shown to be excellent in the non-linear regression of involution equation and exponential equation pattern compared with the findings of linear regression analysis.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.85-95
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• 2016

In this study, furfural, which is one of the value-added chemicals, was produced from the hydrolyzate of Quercus mongolica using dilute acid pretreatment, and the optimal pretreatment condition was determined by Response Surface Methodology (RSM) to obtain high yield of furfural. Based on Central Composite Design, the pretreatment experiment was designed with parameters such as reaction temperature ($X_1$), acid concentration ($X_2$), and reaction time ($X_3$) as independent variables, while dependent variable was furfural concentration (Y), and furfural yield (Z) was shown as percentage of Y per a dry weight basis. According to results of RSM, it was confirmed that reaction temperature ($X_1$) was the most influence factor and reaction temperature ($X_1$)-acid concentration ($X_2$) was the most significant interaction factor on furfural yield. Also, the optimal condition for the highest furfural yield was predicted at reaction temperature of $184^{\circ}C$, acid concentration of 1.17%, and reaction time of 5 min by RSM, and expected maximum yield of furfural was 6.37%. Experimentally, the maximum yield of furfural produced at above optimal condition was 6.21%, and it was considerably similar with the predicted value, and therefore the model for furfural production from the hydrolyzate of Quercus mongolica during dilute acid pretreatment could be built using RSM.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.419-426
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• 2015

The purpose of this study is to investigate experimentally the optimum mix design and site application case of soil mixing wall (SMW) method which is cost-effective technique for construction of walls for cutoff wall and excavation support as well as for ground improvement before constructing LNG storage tank typed under-ground. Considering native soil condition in site, main materials are selected ordinary portland cement, bentonite as a binder slurry and also it is applied $1,833kg/m^3$ as an unit volume weight of native soil, Variations for soil mixing wall are as followings ; (1) water-cement ratio 4cases (2) mixing velocity (rpm) 3levels (3) bleeding capacity and ratio, compressive strength in laboratory and site application test. As test results, bleeding capacity and ratio are decreased in case of decreasing water-cement ratio and increasing mixing velocity. Required compressive strength (1.5 MPa) considering safety factors in site is satisfied with the range of water-cement ratio 150% below, and test results of core strength are higher than those of specimen strength in the range of 8~23% by actual application of element members including outside and inside in site construction work. Therefore, optimum mix design of soil mixing wall is proposed in the range of unit cement $280kg/m^3$, unit bentonite $10kg/m^3$, water-cement ratio 150% and mixing velocity 90rpm and test results of site application case are satisfied with the required properties.