• International Journal of Concrete Structures and Materials
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• v.7 no.1
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• pp.35-50
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• 2013

Rapid and effective repair methods are desired to enable quick reopening of damaged bridges after an earthquake occurs, especially for those bridges that are critical for emergency response and other essential functions. This paper presents results of tests conducted as a proof-of-concept in the effectiveness of a proposed method using externally bonded carbon fiber reinforced polymer (CFRP) composites to rapidly repair severely damaged RC columns with different damage conditions. The experimental work included five large-scale severely damaged square RC columns with the same geometry and material properties but with different damage conditions due to different loading combinations of bending, shear, and torsion in the previous tests. Over a three-day period, each column was repaired and retested under the same loading combination as the corresponding original column. Quickset repair mortar was used to replace the removed loose concrete. Without any treatment to damaged reinforcing bars, longitudinal and transverse CFRP sheets were externally bonded to the prepared surface to restore the column strength. Measured data were analyzed to investigate the performance of the repaired columns compared to the corresponding original column responses. It was concluded that the technique can be successful for severely damaged columns with damage to the concrete and transverse reinforcement. For severely damaged columns with damaged longitudinal reinforcement, the technique was found to be successful if the damaged longitudinal reinforcement is able to provide tensile resistance, or if the damage is located at a section where longitudinal CFRP strength can be developed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.910-915
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• 2012

In this paper, the loading methods of EOTS for an exploratory developing fighter were analysed by the technical characteristics of it's operation, maintenance, engineering technology and development cost. By the analysis of operational ability evaluation, the internal type had the merits of stealth function, but the external loading type was preferable to certificate the accessibility, install/detach, compatibility and interoperability with the existing fighter aircraft. From the results of 17 items of technology and development cost evaluation, we found out that the internal type had the advantage of small sizing lightweight, but the external type was highly estimated in the field of application of domestic technology, cost reduction and technical stability for achievement of performance.

• Journal of Korean Society of Steel Construction
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• v.20 no.3
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• pp.377-387
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• 2008

The post-buckling behavior of slender members, such as the chord of truss structures generally implies extreme strength degradation. The buckling strength is usually determined as the performance of the compressed steel members, so it is important to understand the exact buckling behavior of a member in order to design the entire structure. A target analytical model is usually divided by beam or shell element when we simulate the buckling behavior of a compressed steel member such as atruss member. In this case, it is possible to accurately obtain the behavior, but such would be expensive and would require experience inanalysis even in monotonic loading. In this paper, we propose a consistent and convenient method to analyze the post-buckling behavior of elastoplastic compression members. The present methods are formulated to satisfy the second law of thermodynamics. Three numerical examples were tested to determine the validity of the proposed model in cyclic loading with comparable F.E.M results.

• Steel and Composite Structures
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• v.36 no.2
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• pp.163-177
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• 2020

Concentrically Braced Frames (CBFs) are commonly used in the construction of steel structures because of their ease of implementation, rigidity, low lateral displacement, and cost-effectiveness. However, the principal disadvantage of this kind of braced frame is the inability to provide deformation capacity (ductility) and buckling of bracing elements before yielding. This paper aims to present a novel Composite Buckling Restrained Fuse (CBRF) to be utilized as a bracing segment in concentrically braced frames that allows higher ductility and removes premature buckling. The proposed CBRF with relatively small dimensions is an enhancement on the Reduced Length Buckling Restrained Braces (RL-BRBs), consists of steel core and additional tensile elements embedded in a concrete encasement. Employing tensile elements in this composite fuse with a new configuration enhances the energy dissipation efficiency and removes the tensile strength limitations that exist in bracing elements that contain RL-BRBs. Here, the optimal length of the CBRF is computed by considering the anticipated strain demand and the low-cyclic fatigue life of the core under standard loading protocol. An experimental program is conducted to explore the seismic behavior of the suggested CBRF compare with an RL-BRB specimen under gradually increased cyclic loading. Moreover, Hysteretic responses of the specimens are evaluated to calculate the design parameters such as energy dissipation potential, strength adjustment factors, and equivalent viscous damping. The findings show that the suggested fuse possess a ductile behavior with high energy absorption and sufficient resistance and a reasonably stable hysteresis response under compression and tension.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.61-70
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• 2011

This study developed a permanent deformation model for asphalt concrete based on shear properties. Repeated load triaxial compression (RLTC), triaxial compressive strength, and indirect tension strength tests were performed for the three types of asphalt mixtures at various loading and temperature conditions to correlate shear properties of asphalt mixtures to rutting performance. For the given mixtures, as testing temperature increased, cohesion decreased, but friction angle was insensitive to temperature at $40^{\circ}C$ or higher. It was observed that deviatoric stress, confining pressure, temperature, and load frequency affected the permanent deformation of asphalt mixtures significantly. The permanent deformation model based on shear stress to strength ratio and loading time was developed using the laboratory test results and calibrated using accelerated pavement test data. The proposed model was able to predict the permanent deformation of the asphalt mixtures in a wide range of loading and temperature conditions with constant model coefficients.

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.13-22
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• 2015

This study suggests mixing steel fibers in concrete to secure the toughness of the columns. Therefore, to evaluate the structural behavior of welded built-up square columns filled with steel fiber reinforced concrete, ten stub column specimens were fabricated for compressive loading test with variables of steel fiber mixing ratio and loading condition. It is deduced that the steel fibers continue to provide tensile strength even after the concrete cracks and thus improve the strength and behavior of the column when bending moment is applied to it. A small amount of steel fibers can improve compressive strength and bending strength and thus produce economically efficient results when employed in structural design.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.18
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• pp.7611-7615
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• 2014

Aims: To prepare 5-fluorouracil (5-Fu) nanoparticles with higher encapsulation efficiency and drug loading, and then investigate interaction with the SGC-7901 gastric cancer cell line. Materials and Methods: Prescription was optimized by orthogonal experiments, the encapsulation efficiency and loading capacity were tested by high-performance liquid chromatography, and inhibition of proliferation by 5-Fu nanoparticles and 5-Fu given to cells for 24, 48 and 72 hours was investigated by methyl thiazolyl tetrazolium assay (MTT). In addition, 5-Fu nanoparticles were labeled by fluorescein isothiocyanate (FITC), and absorption into cells was tested by flow cytometry. Results: The optimal conditions for preparation were concentrations of 5-Fu of 5mg/ml, of $CaCl_2$ of 60 mg/ml and of chitosan of 2 mg/ml. With a stirring speed of 1200rpm, encapsulation efficiency of 5-Fu nanoparticles was $55.4{\pm}1.10%$ and loading capacity was $4.22{\pm}0.14%$; gastric cancer cells were significantly inhibited by 5-Fu nanoparticles in a time and concentration dependent manner, and compared to 5-Fu with slower drug release, in a certain concentration range, inhibition with 5-Fu nanoparticles was stronger. 5-Fu nanoparticles were absorbed by the cells in line with the concentration. Conclusions: 5-Fu nanoparticles can inhibit growth of gastric cancer cells in vitro to a greater extent than with 5-Fu with good adsorption characteristics, supporting feasibility as a carrier.

• Journal of the Korean Geosynthetics Society
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• v.10 no.3
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• pp.53-62
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• 2011

This paper presents the characteristics behavior of dike structure and foundation ground through the shaking table model test. The vibration loadings of design earthquake acceleration of 0.154g was applied to this laboratory model test regarding on dike structure and foundation ground under the structure. The model was formulated with 1/100 design of representative cross section for evaluating the effectiveness of vibration. Based on the test results, we can analysis the behavior of lateral displacement and settlement characteristics of structure under the earthquake loading. The pore water pressure was also monitored in the upper, middle and lower layers of ground. Finally, the actual displacements and pore water pressure of the structure can be predicted by using the results of the laboratory shaking table test.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.1010-1016
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• 2000

Effect on the bio-mass and nutrient yield of Lemna perpusilla Torry was studied at two nutrient loading frequencies. Six polythene sinks ($6{\times}2{\times}0.5m^{3}$ area) randomly allocated to two treatments having three sinks in each treatment. Each sink containing $6{\times}2{\times}0.35m^{3}$ water body, was changed either daily with 12.6 kg anaerobically fermented cattle manure (effluent) or with 76 kg efluent at six-day interval. Media Kjeldhal-N (40 vs. 36 mg/L; p>0.05) and $NH_3$-N (9 vs 7 mg/L; p<0.05) concentration were higher in daily charged sinks than those charged at six-day interval. However, temperature ($28.48{^{\circ}C}\;vs.\;28.60{^{\circ}C}$) and pH (6.82 vs. 6.84) were sinilar in both groups of sinks. Biomass (93 vs. $80g/m^{2}/d$) and crude protein (1.24 vs. $1.11g/m^{2}/d$) yield were non-significantly (p>0.05) higher in the daily charged than 6-d interval charged ponds. However, dry matter (4.52 vs. 4.15%), organic matter (83 vs. 84%), crude protein (31.4 va. 29.6%) and organic carbon (47 vs. 47%) content were similar in both daily and 6-d interval charged ponds. There were no apparent relationships between the crude protein content of Lemna and the media Kjeldhal-N or $NH_3$-N concentration apparently due to saturated level of nutrient (N in particular). It was concluded that with the level of effluent used for two treatments, nutrient-loading frequency had no significant effect on the biomass and protein yield of Lemna. Technique described here can be used for year-round duckweed production from fermented cattle manure for feeding poultry/fish in smallholder production system.

• 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.