• Journal of Industrial Technology
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• v.18
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• pp.363-370
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• 1998

This study focused on the development of an alternative stress estimation procedure to instantly calculate the critical stresses bonded concrete pavement. Closed form analysis is commonly used to analyze pavement structures. This type of analysis assumes linearelastic material properties and static loading conditions. The well-known ILLI-SLAB finite element program was used for the analysis. Bonded concrete overlay analyzed the stress distribution, behavior and load carrying capacity under track load is made evaluation standard of bonded concrete overlay. In the study, the following results were derived ; The properties of strength is that compress and 3-point bending strength of existing pavement is deteriorated with $184kg/cm^2$, $59kg/cm^2$ but compress and splitting tensile strength of overlay is satisfied with $465kg/cm^2$, $45kg/cm^2$. Load transfers is happen at adjacent slab by interlocking under track load. The stress distribution under interior, corner and edge load is described high loading position surrounding then loading position.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.480-488
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• 2000

Cabbage is the most important vegetables in korea. The cabbage production was based on arduous human labor. A comprehensive research for substituting the human work by machines has been performed at present. In general, cabbage is cultivated on hillside in korea. The harvested cabbage in a field and carrying it to a vehicle for transportation are very laborious work. Hand labor in cabbage transportation to the market damages the quality of cabbage and is also a cause to increase the cost of cabbage production. This study was to design and evaluate a prototype cabbage loader for deserving efficient and safe transportation of cabbage. The developed cabbage loader was a semi-tracked vehicle operated by a hydraulic system, allowing the safe transporting and the loading of cabbage in a steep field. The maximum loading capacity of the loader was 1.0 ton. By using safety devices attached to the loader, the static slopes were 34.0% and 37.4% for the left and the rear roll-over, respectively. The maximum field speed was about 6km/hr with two cabbage pallets of 750kg at a 25% inclined field. The field capacity was about 35 pallets/hr in case of picking up, carrying and unloading two cabbage pallets. The field efficiency of the loader was analyzed to be more than 8 times in comparison of the conventional human labor. The developed loader would be applied for loading and carrying the other vegetables due to the similarity of operations. The study suggested a standard approach to the design of field machines operated in a steep field.

• Journal of Veterinary Science
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• v.23 no.1
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• pp.1.1-1.11
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• 2022

Background: The poor bioadhesion capacity of tilmicosin resulting in treatment failure for Staphylococcus aureus small colony variants (SASCVs) mastitis. Objectives: This study aimed to increase the bioadhesion capacity of tilmicosin for the SASCVs strain and improve the antibacterial effect of tilmicosin against cow mastitis caused by the SASCVs strain. Methods: Tilmicosin-loaded chitosan oligosaccharide (COS)-sodium carboxymethyl cellulose (CMC) composite nanogels were formulated by an electrostatic interaction between COS (positive charge) and CMC (negative charge) using sodium tripolyphosphate (TPP) (ionic crosslinkers). The formation mechanism, structural characteristics, bioadhesion, and antibacterial activity of tilmicosin composite nanogels were studied systematically. Results: The optimized formulation was comprised of 50 mg/mL (COS), 32 mg/mL (CMC), and 0.25 mg/mL (TPP). The size, encapsulation efficiency, loading capacity, polydispersity index, and zeta potential of the optimized tilmicosin composite nanogels were 357.4 ± 2.6 nm, 65.4 ± 0.4%, 21.9 ± 0.4%, 0.11 ± 0.01, and -37.1 ± 0.4 mV, respectively; the sedimentation rate was one. Scanning electron microscopy showed that tilmicosin might be incorporated in nano-sized crosslinked polymeric networks. Moreover, adhesive studies suggested that tilmicosin composite nanogels could enhance the bioadhesion capacity of tilmicosin for the SASCVs strain. The inhibition zone of native tilmicosin, tilmicosin standard, and tilmicosin composite nanogels were 2.13 ± 0.07, 3.35 ± 0.11, and 1.46 ± 0.04 cm, respectively. The minimum inhibitory concentration of native tilmicosin, tilmicosin standard, and tilmicosin composite nanogels against the SASCVs strain were 2, 1, and 1 ㎍/mL, respectively. The in vitro time-killing curves showed that the tilmicosin composite nanogels increased the antibacterial activity against the SASCVs strain. Conclusions: This study provides a potential strategy for developing tilmicosin composite nanogels to treat cow mastitis caused by the SASCVs strain.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.203-212
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• 1999

This paper describes a deadweight force standard machine with the weight change mechanism which can be used as a primary force standards at a national metrology institute. Since commercial deadweight force machine can generate forces by hanging weights to the weight supporter serially, force steps from deadweight force measuring devices of each having different capacity. In order to increase the force steps, we have specially designed a weight mechanism in which the machine can select the necessary weights and generate the load by hanging the selected weights to the weight supporter. The machine can generate 속 force of the range of 2 kN to 110 kN with force step of 1 kN. All weights have been accurately compensated and calibrated by a mass comparator and its standard uncertainty is less than 2.2 ${\times}\;10^{-6}$. The relative expanded uncertainty of the machine is 1.3 ${\times}\;10^{-5}$.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.12
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• pp.35-40
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• 2018

In this study, experimental research was carried out to evaluate the seismic performance of reinforced concrete exterior beam-column joint regions using hybrid retrofitting with AFRP sheets and embedded CFRP reinforcements in existing reinforced concrete building. Therefore it was constructed and tested three specimens retrofitting the beam-column joint regions using such retrofitting materials. Specimens, designed by retrofitting the beam-column joint regions of existing reinforced concrete structure, were showed the stable failure mode and increase of load-carrying capacity due to the effect of crack control at the times of initial loading and confinement of retrofitting materials during testing. Specimens RBCJ-SRA3 designed by the retrofitting of AFRP sheets and embedded CFRP reinforcements in reinforced exterior beam-column joint regions were increased its maximum load carrying capacity by 1.86 times and its energy dissipation capacity by 1.65 times in comparison with standard specimen RBCJ for a displacement ductility of 5.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.32-39
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• 2021

Recently, necessities of steel form for reinforced concrete beam and girder have been emphasized in building structures for the reduction of the construction period and the labor cost. SY Beam was developed for the these purposes and is roll-formed using thin steel plate. On this research, we tried to evaluate and verify the performance and behavior of SY Beam under construction loading stage as like pouring in situ concrete. For the standard shape of SY beam, structural modelling with various steel thicknesses has carried out using MIDAS GEN program. From results of modelling, the width and height of SY Beam were determined 600mm and 400mm respectively. For 3 SY Beams, the loading experiment was performed to measure vertical and horizontal displacement under stacking sand, concrete block, and bundle of rebar. As a result, the vertical deflection showed a tendency to decrease as the thickness increased. In the horizontal displacement, the trend according to the thickness was not clearly observed. From the evaluation on the loading experiment, it is considered that the SY Beam can secure both workability and structural safety. In particular, the SY Beam(1.2mm) hardly generates horizontal displacement, so it has excellent load-bearing capacity. So, we judged that the SY Beam with 1.2mm steel plate has excellent performance and consider to be immediately commercially available.

• Journal of the Korea Concrete Institute
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• v.25 no.5
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• pp.477-484
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• 2013

In this study, eleven reinforced concrete beams, ground granulated blast furnace slag, replacing recycled coarse aggregate (BRS series) and recycled coarse aggregate with steel fiber (BSRS series), and standard specimen (BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the shear performance of such test specimens, such as the load-displacement, the failure mode and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size. Test results showed that test specimens (BSRS Series) was increased the compressive strength by 9%, the maximum load carrying capacity by 1~6% and the ductility capacity by 1.02~1.13 times in comparison with the standard specimen (BSS). And the specimens (BSRS Series) showed enough ductile behavior and stable flexural failure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.1-10
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• 2014

In this study, thirteen reinforced concrete beams, ground granulated blast furnace slag, replacing recycled coarse aggregate with PVA fiber (BSPG series) and recycled coarse aggregate with hybrid fiber ($BSPGR_1$, $BSPGR_2$ series), and standard specimen (BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the Structural performance of such test specimens, such as the load-displacement, the failure mode, and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size. Test results showed that test specimens ($BSPGR_1$, $BSPGR_2$ series) was increased the compressive strength by 13%, the maximum load carrying capacity by 4~21% and the ductility capacity by 4~28% in comparison with the standard specimen (BSS). And the specimens ($BSPGR_1$, $BSPGR_2$ series) showed enough ductile behavior and stable flexural failure.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.993-1000
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• 2009

In general, a drilled shaft embedded in weathered rock has a large load bearing capacity. Therefore, most of the load tests are performed only up to the load level that confirms the pile design load capacity, and stopped much before the failure load of the pile is attained. If a reliable failure load value can be extracted from the premature load test data, it will be possible to greatly improve economic efficiency as well as pile design quality. The main purpose of this study is to propose a standard for judging the reliability of the failure load of piles that is obtained from extrapolated load test data. To this aim, eleven static load test data of load-displacement curves were obtained from testing of piles to their failures from 3 different field sites. For each load-displacement curve, loading was assumed as 25%, 50%, 60%, 70%, 80%, and 90% of the actual pile bearing capacity. The limited known data were then extrapolated using the hyperbolic function, and the failure load was re-determined for each extrapolated data by the ASCE 20-96 method (1997). Statistical analysis was performed on the reliability of the re-evaluated failure loads. The results showed that if the ratio of the maximum-available displacement to the failure-load displacement exceeds 0.6, the extrapolated failure load may be regarded as reliable, having less than a conservative 20% error on average. The applicability of the proposed standard of judgment was also verified with static load test data of driven piles.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.341-349
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• 2012

Recently, as structures in Korea and other countries become much taller, larger, and more specialized, concrete used for constructions of these structures is required to have high performance characteristics. Especially, seismic performance of concrete must be improved to resist cyclic loading from earthquakes. Consequently, this study was performed to focus on developing optimal mixtures of high ductile fiber reinforced mortar with high ductility and durability, which have good serviceability, stability and reliability performances. Eventually, this material is expected to improve seismic performance of concrete structures such as load carrying capacity, ductility capacity, and energy dissipation capacity when applied to critical regions of flat plate slab-column joint. Ultimately, this research is intended to develop a material for basic designs and practical constructions of reinforced concrete structures. Test results showed that the maximum load carrying capacity, the ductility capacity, and the energy dissipation capacity of the test specimens titled RCFPP series were increased by 15%~34%, by 33%~37%, and by 2.14 times, respectively, compared to those of the standard specimen titled SRCFP.