• International Journal of Highway Engineering
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• v.18 no.4
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• pp.29-35
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• 2016

PURPOSES : The new waste management policy of South Korea encourages the recycling of waste materials. One material being recycled currently is tire-derived fuel (TDF) ash. TDF is composed of shredded scrap tires and is used as fuel in power plants and industrials plants, resulting in TDF ash, which has a chemical composition similar to that of the fly ash produced from coal. The purpose of this study was to evaluate the properties of an asphalt concrete mix that used TDF ash as the mineral filler. METHODS : The properties of the asphalt concrete were evaluated for different mineral filler types and contents using various measurement techniques. The fundamental physical properties of the asphalt concrete specimens such as their gradation and antistripping characteristics were measured in accordance with the KS F 3501 standard. The Marshall stability test was performed to measure the maximum load that could be supported by the specimens. The wheel tracking test was used to evaluate the rutting resistance. To investigate the moisture susceptibility of the specimens, dynamic immersion and tensile strength ratio (TSR) measurements were performed. RESULTS : The test results showed that the asphalt concrete containing TDF ash satisfied all the criteria listed in the Guide for Production and Construction of Asphalt Mixtures (Ministry of Land, Infrastructure and Transport, South Korea). In addition, TDF ash exhibited better performance than that of portland cement. The Marshall stability of the asphalt concrete with TDF ash was higher than 7500 N. Further, its dynamic stability was also higher than that listed in the guide. The results of the dynamic water immersion and the TSR showed that TDF ash shows better moisture resistance than does portland cement. CONCLUSIONS : TDF ash can be effectively recycled by being used as a mineral filler in asphalt, as it exhibits desirable physical properties. The optimal TDF ash content in asphalt concrete based on this study was determined to be 5%. In future works, the research team will compare the characteristics of asphalt concrete as function of the mineral filler types.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.5
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• pp.1303-1317
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• 2024

The development of high-performance underwater propulsion devices has gained importance with the expansion of recreational and industrial diving applications. This study aims to develop and validate a waterjet-type diver propulsion system capable of achieving a top speed of 3.8 knots and an operational time of over 120 minutes. Utilizing advanced modeling and simulation techniques, the design focuses on minimizing hydrodynamic resistance and optimizing buoyancy. Structural and fluid dynamic analyses were conducted to ensure the device's stability and performance under 20 atm pressure at a depth of 200 meters. The propulsion system employs a sensorless BLDC motor and a 36V lithium-ion battery pack to enhance efficiency and reliability. Field tests confirmed an average speed of 3.88 knots and a continuous operation time of 150 minutes, exceeding the initial targets. This research demonstrates significant advancements in diver propulsion technology, providing valuable insights for future underwater equipment development. The outcomes are poised to enhance the safety, efficiency, and usability of diver propulsion devices, with broader applications in marine research, environmental monitoring, and resource exploration.

• Structural Engineering and Mechanics
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• v.41 no.2
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• pp.231-242
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• 2012

This research work aims to develop an optimal design using Finite Element (FE) and Genetic Algorithm (GA) methods to replace the traditional concrete and timber material by a Synthetic Polyurethane fibre glass composite material in railway sleepers. The conventional timber railway sleeper technology is associated with several technical problems related to its durability and ability to resist cutting and abrading action of the bearing plate. The use of pre-stress concrete sleeper in railway industry has many disadvantages related to the concrete material behaviour to resist dynamic stress that may lead to a significant mechanical damage with feasible fissures and cracks. Scientific researchers have recently developed a new composite material such as Glass Fibre Reinforced Polyurethane (GFRP) foam to replace the conventional one. The mechanical properties of these materials are reliable enough to help solving structural problems such as durability, light weight, long life span (50-60 years), less water absorption, provide electric insulation, excellent resistance of fatigue and ability to recycle. This paper suggests appropriate sleeper design to reduce the volume of the material. The design optimization shows that the sleeper length is more sensitive to the loading type than the other parameters.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.63-72
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• 2004

The supply voltage has been drop rapidly and the total length of the wire increased exponentially in the nanometer SoC design environment. The ideal supply voltage was dropped sharply by the resistance and parasitic devices which stayed on the kilometers-long wire length. Even worse, it could severely affect the functional behavior of the block of the design. To analyze the effects of the long wire of the SoC while maintaining the accuracy, the modeling of the current and the RC conversion of the parasitic techniques are researched and applied. By these modeling and conversion, the multi-million gates HDTV Chipset can be analyzed within a day. The benchmark analysis of the HDTV SoC showed the superiority to the conventional methods in performance and accuracy.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1035-1047
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• 2015

Starting from a new dynamic system description novel synchronous machine deterministic observers are proposed. Reduced and full order adaptive observer variations are presented. Based on the feedback linearization control law and the use of deterministic observer a novel control system is built. It meets the requirements of high performance tracking system. Adaptivity to stator and rotor resistance and the torque sensorless application is included. The comparison of the proposed novel control with conventional linear and nonlinear control systems is discussed. The given simulational study includes complete drive system integration.

• The Journal of the Acoustical Society of Korea
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• v.2 no.1
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• pp.48-58
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• 1983

The transient sound radiation from the impact between a steel ball and a thick plate is analyzed theoretically and compared with experiment results. The derivation process itself is difficult to analyze sound radiation characteristics theoretically for a thick plate with some resonances but may be investigated from measured data. During mechanical impacts, arbitrary driving point importance for an elastic system enables to predict by using mechanical importance method. In order to obtain approximate solution for an impact model testing, the surface Helmholtz integral formulation based on the integral expression for pressure in the field in terms of surface pressure and normal velocity is used as a basis. A simple expression is developed for an impulsive response function, which is time dependent velocity potential and pressure for an impact may then be computed by a convolution of exciting force. In estimating of elastic-acoustical correlation problems, mechanical inertance, overall transfer function and radiation resistance obtained by signal processing techniques are used. The usefulness is confirmed by applying these methods prediction of arbitray driving pint inertance, radiated sound pressure and exciting force.

• Journal of the Korean Geotechnical Society
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• v.40 no.5
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• pp.7-20
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• 2024

Ground improvement techniques through soil densification are widely used to enhance the cyclic resistance and seismic performance of liquefiable soils. However, most studies have primarily focused on the increase in soil strength before and after ground improvement, with limited investigation into changes in spatial statistical characteristics. This study aims to identify the changes in soil strength and spatial variability due to ground improvement by analyzing data from 19 cases where ground improvement was conducted using timber piles, aggregate piers, and dynamic compaction, with a cone penetration test (CPT) performed pre- and post-improvement. The changes in cone tip resistance were evaluated by comparing cone tip resistance profiles before and after ground improvement, while changes in spatial variability were assessed by examining variations in three parameters of the random field: mean (or trend function), variance, and scale of fluctuation. The results indicate that cone tip resistance generally increased, while inherent variability tended to decrease. The scale of fluctuation, representing spatial autocorrelation, generally increased following ground improvement, with higher initial fluctuation parameters correlating with a greater rate of increase. Furthermore, the probabilistic analysis of liquefaction-induced settlement revealed that changes in the scale of fluctuation due to ground improvement significantly influenced the variability of settlement, underscoring the importance of considering this factor.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1049-1052
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• 1997

The pupose of this study on the surface finishing is to examine the performance of brushing as a means of reducing the surface roughness of the precision theaded shafts in ball screw assemblies. Ball screws provide superior performance compared to other types of screw feeds in terms of static and dynamic rolling resistance,backlash,and wear characteristics. The Reduction of the surface roughness of the lead shaft in ball screw assembiles is essential for precision movement,high speed/low noise tracel, and for low wear/long life. To reduce machine dependent errors that would influence the surface roughness compared with other lapping or polishing techniques,experiments will be performed using special wire brushes to polish precision ground shafts. The best results were obtained using the Al /sab 2/O /sab3/ brushes, with the Al /sab 2/O /sab3/ #500 grit brush producing a surface finish of approximately 0.7 .mu.m, and the Al /sab 2/O /sab3/ #600 grit producing a surface finish of approximately 0.8 .mu.m. Both of these results were produced at the highest wheel polishing speed of 3520 rpm. The SiC #500 brush produced a surface roughness of approximately 1 .mu.m at 3520 rpm.

• The Research Journal of the Costume Culture
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• v.22 no.5
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• pp.688-701
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• 2014

This study examined the expression characteristics in pop art works of Jean-Charles de Castelbajac. The study here aimed at possibility to find a design development in building up the unique art world of creativity based on popularity, artistry, and originality without confinement to the trend only. For the research method, review of literature and analysis about Castelbajac's works reflecting the pop art feature in the collections from 2000S/S to 2012F/W were performed. The results of research are as follows. The external expression form of Castelbajac's works based on pop art was grouped roughly into use of mass culture image, appropriation of pop art expression technique, and parody of art works. First, his work appeared as application of the mass culture image such as symbolic thing in the modern consumer society, object in an ordinary life, character of well-known animation, national flag and famous star. Second, such appropriated pop art techniques showed as pop color in strong primary color and silk screen, photomontage, collage, assemblage, graffiti, and lettering. Third, a variety of images featured earlier in art works were shown in parody. These works are valuable in that they are expressed aesthetically through regeneration of popular culture's various images in view of fashion, they are described in the non-traditional value with frolic resistance and deviation out of existing fashion norm, and they are given the dynamic creativity integrated with art and fashion.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1623-1634
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• 2022

A new irradiation loop design has been developed, which provides the ability to carry out radiolytic resistance studies of extraction systems simulating process relevant conditions in an easy and simple way. The step-by-step loop configuration permits an easy modification of settings and has a relative low volume requirement. This irradiation loop has been initially set up to test the main EURO-GANEX process steps: the lanthanide (Ln) and actinide (An) co-extraction followed by the transuranic (TRU) stripping. The performance and changes in the composition have been analyzed during the irradiation experiment by different techniques: gamma spectroscopy and ICP-MS for the extraction and corrosion behavior of the full system, and HPLC-MS and Raman spectroscopy to determine the degradation of the organic and aqueous solvents, respectively. The Ln and An co-extraction step and the corrosion that occurred during the first irradiation step revealed the favorable expected results according to literature. The effects of acidity changes occurred during the irradiation process, the presence of stainless corrosion products in solution as well as the new possible degradation compounds have been explored in the An stripping step. The results obtained demonstrate the importance of developing realistic irradiation experiments where different factors affecting the performance can be easily studied and isolated.