• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.243-254
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• 2013

Internally Confined Hollow RC(ICH RC) column consisted of concrete, transverse reinforcement, longitudinal reinforcement, and inner tube. It had good strength and ductility by core concrete was become triaxial confining state with transverse reinforcement and inner tube. There were two confining stress as external confining stress and internal confining stress in an ICH RC column. While external confining stress was researched by former researchers, internal confining stress has not researched. In this paper, confining stress of both Hollow RC column and ICH RC column was investigated using FEA program. Relation between theoretical confining stress and internal confining stress was drawn by analysis results. Modified failure condition equations of inner tube were suggested to base on failure condition equations of inner tube by former researcher. When thickness of inner tube was calculated by modified equations, it could be economic because thickness of inner tube was reduced 50% compared with former researcher equations in order to same confining stress.

• The Journal of the Korea Contents Association
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• v.17 no.10
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• pp.300-306
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• 2017

The purpose of this study was to investigate the antibacterial effect of functional multiwall carbon nanotube (MWCNT) on the conventional glass ionomer cement(GIC). The MWCNT was incorporated into a commercial powder at 0.125, 0.25, 0.5 and 1.0 wt%. Specimens for vickers hardness(VHN) disks(Ø$10mm{\times}2mm$) each were prepared. Indention were made using a load of 200 N and 20 s dwell on four specimens for each distilled water storage time 1d, 7d, and 14days. The antibacterial effects using agar diffusion test with S. mutans and S. aureus. The diameters of the inhibition zones produced around the materials were measured. The results revealed that all the vickers hardness values were increase significantly with incubation time(p<0.05). Regarding the antibacterial effect for S. mutans, all the tested groups showed a slightly higher value not significantly with the control group(p<0.05). However S. aureus statistical analysis indicated a significant difference for antibacterial agents between control and MWCNT containing 0.25 wt%(p<0.05). These results of this study provide that the conventional GIC with containing MWCNT show good antibacterial effect against and favorable mechanical properties. Further this study on the efficient functionalization of multiwall carbon nanotube will be needed.

• Journal of Conservation Science
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• v.17 s.17
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• pp.39-56
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• 2005

The Gwangtonggyo(bridge) on the Cheonggyecheon(river) is mainly composed of biotite granite with coarse grain. The rock consists mainly of quartz, plagioclase, microcline, orthoclase and biotite with lesser amount of muscovite, sericite and chlorite. Muscovite and sericite may be formed from feldspars and chlorite from biotite by alteration(including weathering). These rocks are relatively deteriorated by weathering, polluted water running the river and heavy traffic. The main phenomena of damages are surface exfoliation, grain separation, deceleration, pollution of organic and heavy chemical elements, cracks and breakage. These phenomena have been analyzed by polarized microscope, XRD and SEM/EDX. The analyzed results show organic pollution and secondarily formed gypsum and apatite on the rock surface and micro-pores. NaCl and $CaCO_3$ as rock salt and calcite probably may be formed secondarily in some points. Also heavy chemical elements such as Cr, Pb, Pd, W, La, Zn and Nd are polluted in some samples. The contacts between rocks are generally breakdown in small scale or cracks are developed due to mainly load and vibration shock of heavy traffic.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.41-50
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• 2006

In this paper, sets of engineering analyses were conducted to renew the overall dimensions and configurations of a disposal container proposed as a prototype in the previous study. Such efforts and calculation results can provide new design variables such as the inner basket array type and thickness of the outer shell and the lid & bottom of a spent nuclear fuel disposal container. These efforts include radiation shielding and nuclear criticality analyses to check to see whether the dimensions of the container proposed from the mechanical structural analyses can provide a nuclear safety or not. According to the results of the structural analysis of a PWR disposal container by varying the diameter of the container insert, the Maximum Von Mises stress from the 102 cm-container meets the safety factor of 2.0 for both extreme and normal load conditions. This container also satisfies the nuclear criticality and radiation safety limits. This decrease in the diameter results in a weight loss of a container by $\sim20$ tons.

• Journal of Biosystems Engineering
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• v.37 no.3
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• pp.155-165
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• 2012

This study was performed to offer the data for design of the seedling bed transfer equipment to make the automation of working process in a plant factory. The seedling bed transfer equipment pushing the seedling bed with bearing wheels on the rail for interconnecting each working process by a pneumatic cylinder was made and examined. The examined transfer force to push the seedling bed with a weight of 178.9 N by the pneumatic cylinder with length of 60 cm and section area of 5 $cm^2$ was measured by experiments. The examined transfer forces was compared with theoretical ones calculated by the theoretical formula derived from dynamic system analysis according to the number of the seedling bed and pushing speed of the pneumatic cylinder head at no load. The transfer function of the equipment with the input variable as the pushing speed $V_{h0}$(m/s) and the output variable as the transfer force f(t)(N) was represented as $F(s)=(V_{h0}/k)(s+B/M)/(s(s^2+Bs/M+1/(kM))$ where M(kg), k(m/N) and B(Ns/m) are the mass of the bed, the compression coefficient of the pneumatic cylinder and the dynamic friction coefficient between the seedling bed and the rail, respectively. The examined transfer force curves and the theoretical ones were represented similar wave forms as to use the theoretical formular to design the device for the seedling bed transfer. The condition of no vibration of the transfer force curve was $kB^2>4M$. The condition of transferring the bed by the repeatable impact and vibration force according to difference of transfer distance of the pneumatic cylinder head from that of the bed was as $Ce^{-\frac{3{\pi}D}{2\omega}}<-1$, where ${\omega}=\sqrt{\frac{1}{kM}-\frac{B^2}{4M^2}}$, $C=\{\frac{\frac{B}{2M}-\frac{1}{kB}}{\omega}\}$, $D=\frac{B}{2M}$. The examined mean peak transfer force represented 4 times of the stead state transfer force. Therefore it seemed that the transfer force of the pneumatic cylinder required for design of the push device was 4Bv where v is the pushing speed.

• Archives of design research
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• v.15 no.4
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• pp.263-274
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• 2002

This study aims to analyze the image of long-span structures. For the intention, it analyzes the relationship between images and physical attributions of elements such as materials, stresses, configurations, compositions and shapes of structures. The image of structures can represent following 5 factors; friendly-unfriendly, strong-weak, dynamic-calm, superior-inferior, and regular-irregular. The friendly-unfriendly in the image of structure mostly determines on a finished material and partly with a structural shape. The strong-weak in the image of structure determines on configuration of the structural members. The dynamic-calm in the image of structure determines on the structural shape. Hence the structure has dynamic forms when it seems to be open and sharp, namely when it receives the flow of forces in the structural shape, and it has a (-) gauss curved rate or an diagonal appearance. The superior-inferior in the image of structure determines on composition of structural elements. The structure seems to be superior is contributed not simply to support load but positively to create design as a tectonic element. From now on, this study can provide the useful information on the long-span structure design through the more appropriate analysis of the image.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.1
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• pp.1-10
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• 1999

The north-west sea area of Cheju Island is where originate two layer current in the summer season. The case of the fishing operations in this sea area is almost impossible for normal expansion of the net gear for shooting net, and is happened to be frequent occasions for rise of tension suddenly in purseline by changes of the net shapes in the operation. Therefore, the safety of the operations is often obstructed by the above mentioned. In connection with the above, model experiments on the purse seine in the circulating water tank was carried out in comparison and analysis on the changes of tension in the pruseline by deformation of purse seine in the sea area of two layer current. THe results obtained are as follows;In the case of the required time for pursing of 20 minutes in the no current set, the increasing curve for tension of purseline can be expressed as:Y=0.0004x3+0.0098x2+0.3000x(r=0.9989)where Y is tension(metric tons) of a purseline, x is required time(minutes) for pursing. And, the maximum value of tension in this time was an increase of 31.3 percent at 15 minutes, and was a decrease of 30.3 percent at 30 minutes than that of 20 minutes.When the bottom margin of net is held on the position in velocity of 0.5 knot at three-eighths of net in the bottom current to the net height, the maximum tension of the required time for pursing of 30 minutes in tight set and loose set were decrease of 29.5 percent and 28.7 percent respectively than that of 20 minutes.The work load during the required time for pursing of 20 minutes were calculated 5.79×106 kgf·m in no current set, 7.89×106 kgf·m in tight set and 5.15×106 kgf·m in loose set, therefore it was an increase of 22.3 percent in tight set, and was a decrease of 11.1 percent in loose set than that of the no current set. Where tight set and loose set is a range of the bottom current with velocity of 0.5 knot at three-eighths of net to the net height.

• Journal of Conservation Science
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• v.16 s.16
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• pp.77-88
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• 2004

This study evaluates the occurrences, phyfical weathering and biological deterioration on rock properties during the dissection process an object of stone pagoda in the Mireuksaji temple site. For restoration and conservation, all kinds of rock properties are carried out detailed scientific investigation and diagnosis. Constituting rocks of the pagoda composed mainly of equi-granular medium grained biotite that rock properties presumed to be use about 3,000 materials. Main external properties of the pagoda are total 446 materials, and the rock properties under the concentration load on the each floors occurred with overlapping fracture, weathering and deteriorations. The 84 materials show highly degraded about $18.8\%$ among the external properties. Representative physicochemical deteriorations are fracture, loss, break, exfoliation, degradation, grain shaped dissolution, relief surface, discoloration and hydroxide precipitates, in this study, the deterioration state of each properties give a precisely description and analysis. Coverage of lichen and algae on the rock surface represented about $85\%$. As the some properties, biological contaminants withered up when spray rock surface with diluted cleaning chemicals. Results of the study are utilized an application for restoration system and detailed investigation during the dissection process of stone cultural properties.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.135-146
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• 2015

To provide the data necessary to determine the design wind speed for calculating the wind load acting on a greenhouse, we measured the wind speed below 10m height and analyzed the power law exponents at Buan and Gunwi. A wind speed greater than $5m{\cdot}s^{-1}$ is appropriate for calculating the power law exponent necessary to determine the wind speed distribution function according to height. We observed that the wind speed increased according to a power law function with increased height at Buan, showing a similar trend to the RDC and JGHA standards. Therefore, this result should be applied when determining the power law function for calculating the design wind speed of the greenhouse structure. The ordinary trend is that if terrain roughness increases the value of power law exponent also increases, but in the case of Gunwi the value of power law exponent was 0.06, which shows contrary value than that of the ordinary trend. This contrary trend was due to the elevations difference of 2m between tower installed and surrounding area, which cause contraction in streamline. The power law exponent started to decrease at 7 am, stopped decreasing and started to increase at 3 pm, and stopped increasing and remained constant at 12 pm at Buan. These changes correspond to the general change trends of the power law exponent. The calculated value of the shape parameter for Buan was 1.51, confirming that the wind characteristics at Buan, a reclaimed area near the coast, were similar to those of coastal areas in Jeju.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.33-38
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• 2017

The number of damaged lifeline structures have been increasing with urban acceleration under earthquakes. To predict the damage, damage mitigation technology of lifeline structures should be analyzed using damage prediction technology. Therefore, in this paper, the degree of the fragility of structures under an earthquake was evaluated stochastically through an evaluation of the seismic fragility. The aim was to develop damage prediction technology of sewage pipes among the lifeline facilities. The site response was performed using the data from 158 boreholes in Seoul and 7 real earthquake waves to determine the responses in real urban areas. The seismic fragility was deduced through a total of 29822 time history analysis. In addition, sewer pipes were evaluated and the persisting period was passed by applying the research results of strength reduction which is due to sulphate erosion. As a result, the difference in failure probability between 300 and 800 with the smaller diameter of the representative pipes was approximately double and the size of the pipes has a significant effect on the seismic fragility function. Moreover, the failure probability of a seismic load increases by up to 10 fold as the strength reduction rate increases. The results of this study can be used as a means of predicting the damage and countermeasures of sewer pipes and might be reflected in the seismic design of underground facilities.