• Geomechanics and Engineering
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• v.11 no.3
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• pp.385-400
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• 2016

Bearing capacity of open-ended piles depends largely on inner frictional resistance, which is influenced by the degree of soil plugging. While a fully-plugged open-ended pile produces a bearing capacity similar to a closed-ended pile, fully coring (or unplugged) pile produces a much smaller bearing capacity. In general, open-ended piles are driven under partially-plugged mode. The formation of soil plug may depend on many factors, including wall thickness at the pile tip (or inner pile diameter), sleeve height of the thickened wall at the pile tip and relative density. In this paper, we studied the effects of wall thickness at the pile base and sleeve height of the thickened wall at the pile tip on bearing capacity using laboratory model tests. The tests were conducted on a medium dense sandy ground. The model piles with different tip thicknesses and sleeve heights of thickened wall at the pile tip were tested. The results were also discussed using the incremental filling ratio and plug length ratio, which are generally used to describe the degree of soil plugging. The results showed that the bearing capacity increases with tip thickness. The bearing capacity of piles of smaller sleeve length (e.g., ${\leq}1D$; D is pile outer diameter) was found to be dependent on the sleeve length, while it is independent on the sleeve length of greater than a 1D length. We also found that the soil plug height is dependent on wall thickness at the pile base. The results on the incremental filling ratio revealed that the thinner walled piles produce higher degree of soil plugging at greater penetration depths. The results also revealed that the soil plug height is dependent on sleeve length of up to 2D length and independent beyond a 2D length. The piles of a smaller sleeve length (e.g., ${\leq}1D$) produce higher degree of soil plugging at shallow penetration depths while the piles of a larger sleeve length (e.g., ${\geq}2D$) produce higher degree of soil plugging at greater penetration depths.

• Journal of Environmental Health Sciences
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• v.34 no.1
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• pp.101-107
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• 2008

Bio-filtration utilizes microorganisms fixed to a porous medium to metabolize pollutants present in an air stream. The microorganisms grow in a bio-film on the surface of a medium or are suspended in the water phase surrounding the medium particles. Therefore, bio-filter support media play one of the most important key roles in bio-filtration of gas phase pollutants. To characterize and select the appropriate support media, gas adsorption capacity and microorganism immobilization were investigated in lab-scale experiments for the selected target support media which were compost I (compost from lab-scale process), compost II (compost from municipal facility), bark, wood chip, orchid stone and vermiculite. As odor materials, ammonia and trimethylamine were utilized. From the result of experiments, bark was superior to any other support media tested in adsorption capacity as much as 12.5 mg ammonia per 1 g bark. In trimethylamine adsorption, bark and wood chip showed a remarkable results of 21.1 and 14.1 mg/g respectively. On the other hand, microorganism fixation test determined by the count of nitrogen oxidizing microbes population, the compost II and wood chips showed the best results. Considering the characteristics of materials and the operating condition of the bio-filter, bark, wood chip, and compost II are applicable to the support media of bio-filter when they are appropriately blended on the basis of studying the media pH, packing porosity and moisture contents.

• Journal of Energy Engineering
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• v.10 no.4
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• pp.318-326
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• 2001

To enhance thermal efficiency of thermal facility through recovery of low and medium temperature waste heat, 1 MW organic Rankine cycle system was designed and developed. The exhaust gases of 175$^{\circ}C$ at two 100 MW power plants in pohang steel works were selected as the representative of low and medium temperature waste heat in industrial process for the heat source of the organic Rankine cycle system. HCFC-123, a kind of harmless refrigerant, was chosen as the working fluid for Rankine cycle. The organic Rankine cycle system with selected exhaust gases and working fluid was designed and constructed. From the operation, it was confirmed that the organic Rankine cycle system is available for low and medium temperature waste heat recovery in industrial process. The optimum operating manuals, such as heat-up of hot water, turbine start-up, and the process of electric power generation, were derived. However, electric power generated was not 1 MW as designed but only 670 kW. It is due to deficiency of pump capacity for supply of HCFC-123. So it is necessary to increase the pump capacity or to decrease the pressure loss in pipe for more improved HCFC-123 supply.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.161-169
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• 1997

This study was conducted to compare the insemination time of bovine oocytes and determine the effects of glucose(1.5 mM) on the development of bovine embryos at early cleavage stage. Oocytes were matured for 24 h, followed by exposure to sperm and cultured in modified Tyrode's media drops or with bovine oviduct epithelial cell monolayer prepared in TCM199(BOECM). Insemination time and culture system were varied in each experiment. In experiment 1, to investigate the developmental capacity of bovine embryos after different time of exposure to sperm, bovine ova and sperm were co-incubated for 18, 30 or 54 h, respectively. The development to blastocysts of 30 and 54 h insemination groups were significantly higher(P<0.05) than 18 h group, and in case of blastocysts of cleaved embryos, 30 h group were significantly higher(P<0.05) than other groups. In experiment 2, we investigated the effect of glucose on early bovine embryos. After 18 h insemination, in vitro fertilized oocytes were separated following 3 groups ; G+0, C+24 and C+48. Oocytes of G+0 group were cultured in glucose added Tyrode's medium after fertilization, oocytes in C+24 and C+48 groups were cultured in glucose free Tyrode's medium after fertilization. After 24 h culture, G+24 group was moved to glucose added medium. All oocytes of 3 groups were moved to BOECM after 48 h culture. The rates of cleavage and development to blastocysts in G+0 group were significantly lower than other groups. In experiment 3, we determined the effects of glucose exposure from 8 to 20 h after insemination on the cleavage and development of oocytes. The oocytes in glucose added group had high capacity of cleavage and further development. This study shows that in bovine oocytes, the optimal exposure to sperm is 30 h and glucose exposure to bovine one-cell embryos is detrimental to their first cleavage and further development in vitro but there has no evidence of detrimental effect of glucose(1.5 mM) exposure to bovine embryos over the two-cell stage in vitro.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.191-196
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• 1996

The objective of this study were to investigate the effects of culture media and additives on the development of bovine in vitro matured(IVM) and in vitro fertilized(IVF) oocytes. In experiment 1, bovine oocytes were cultured in droplets of TC 199 supplemented with 10% fetal bovine serum(FBS) with or without hormones (5$\mu\textrm{g}$/ml FSH, 5$\mu\textrm{g}$/ml LH, 1$\mu\textrm{g}$/ml E2). Cleavage rates of embryos cultured for 40~44hrs after IVF were higher when embryos were cultured in TC 199 supplemented hormones (68.1%, 921/35) than without hormones (52.7%, 77/146), but the percentages of development beyond morulae stage were not difference (20.7%, 19.4%). In experiment 2, the effects of various media such as TC 199, synthetic oviduct fluid(SOF), CR1aa with different energy source (fatal bovine serum, FBS; bovine serum albumin, BSA) on developmental capacity of IVM/IVF bovine embryos were investigated. The developmental rates into morulae and blastocysts were 27.1, 10.7, 6.3 and 0%, respecitvely, in CR1aa plus 3mg/ml BSA, SOF plus 10% FBS, TC 199 plus 10% FBS, SOF plus 3mg/ml BSA. In experiment 3, the comparisons of bovine embryos developed to morulae and blastocysts in different culture media (TC 199, SOF, CR1aa, Menezo's B2) were investigated. The developmental capacity beyond morulae stage were 32.9, 26.6, 11.1 and 7.1%, respectively, in Menezo's B2 plus BSA, CR1aa plus BSA, SOF plus BSA, TC 199 plus FBS medium. The cell numbers of the blastocyst were not different in different cultrue media. In experiment 4, bovine embryos were co-cultured with vobine oviduct epithelial cells(BOEC) in TC 199 plus FBS, SOF plus BSA, CR1aa plus BSA, Menezo's B2 plus BSA. The morula and blastocyst rates were 44.7, 32.9, 26.0 and 23.3%, respectively, in CR1aa TC 199, SOF, and Menezo's B2 medium. The cell numbers of the blastocyst were similar to those of blastocyst developed in different culture media.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.880-886
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• 2010

In this paper, we studied the application of low pressure ultra-violet (UV) lamps for the development of an energy saving ship's ballast water treat (BWT) device. We proposed the optimal arrangement of UV lamps by analyzing the energy radiated from medium- and low-pressure UV lamps. Based on the experimental results, we manufactured a disinfection chamber which is composed of low-pressure UV lamps. The rated power and the treatment capacity of the chamber are 216 [W] and 10 [$m^3$/h], respectively. This can replace a disinfection chamber treated by two 2 [kW] medium pressure lamps. The disinfection performance, however the power consumption is about one-eighteen compare to the medium pressure UV lamp, is over 94 [%] for bacteria, 93 [%] for zooplankton, and 94 [%] for phytoplankton. Therefore, it would be possible to develop an energy saving BWT device in a low capacity below 100 [$m^3$/h].

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.13-22
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• 2015

In this study, a new RCSF (Reinforced Concrete Steel Frame) external connection method is proposed for seismic strengthening of medium-and low-rise reinforced concrete buildings. The RCSF method, proposed in this study, is capable of carrying out the seismic retrofitting construction while residents can live inside structures. The method is one of the strength design approach by retrofit which can easily increase the ultimate lateral load capacity of concrete buildings controlled by shear. The pseudo-dynamic test, designed using a existing school building in Korea, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and ductility. Test results revealed that the proposed RCSF strengthening method installed in RC frame enhanced conspicuously the strength and displacement capacities, and the method can resist markedly under the large scaled earthquake intensity level.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1009-1013
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• 1996

This study was carried to investigate the emulsion stability of microcrystalline chitins (MCC) prepared from chitins of different molecular sizes and different degrees of phosphorylation in a model fatty food system. Chitins of low, medium and high molecular size prepared from crabshells were phosphorylated to 30-50% to make MCC. MCC prepared from chitin of medium molecular size revealed a high emulsion stability. The best emulsion stability was observed in MCC prepared from medium size chitin with 40% phosphorylation (M-40-MCC). The fat binding capacity of MCC was not significantly different among the samples. MCC with 50% phosphorylation had more fat binding capacity, ranging from 650-690%. When 2.46% of M-40-MCC was applied to a coconutoil-water system as an emulsifier, emulsion separation was observed from 10 min after emulsification, indicating that it could not be used as a sole emulsifier. When 50% of emulsifier (Span-60 &Tween-60) in a liquid coffee creamer, selected as a model fatty foods, was replaced by M-40-MCC, emulsion stability was as good as control. Consistency of liquid creamer was decreased and L value increased as the amount of MCC repacement increased. A liquid creamer with 50% emulsifier replaced by MCC had sensory characteristics equivalent to control.

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.147-155
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• 2015

A new SRCF (Steel Reinforced Concrete Frame) external connection method for seismic strengthening of medium-and low-rise reinforced concrete buildings is reported in this paper. The SRCF method, proposed in this study, is capable of carrying out the seismic retrofitting construction while residents can live inside building. The method is one of the strength design approach by retrofit which can easily increase the ultimate lateral load capacity of concrete buildings controlled by shear. The pseudo-dynamic test, designed using a existing school building in Korea, was carried out in order to verify the seismic strengthening effects of the proposed method in terms of the maximum load carrying capacity and deformation. Test results revealed that the proposed SRCF strengthening method installed in RC frame enhanced conspicuously the strength and deformation capacities, and the method can resist markedly under the large scaled earthquake intensity level.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.589-591
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• 2021

In the offshore plant industry, the Access service basket for aerial work is used of for various business purposes. However, various types of safety accidents continue to occur in operating these system. In the case of high-capacity workstations currently in use, workers are exposed to various risks in determining and operating the load capacity, proximity distance, and direction of operation. In this paper, to solve this problem, we develop a device that incorporates IoT-based monitoring and crash alarm systems into aerial work systems. The developed device was tested in the presence of experts to ensure reliability of the device, which allows workers and managers to easily check the operation status and thereby prevent safety accidents in advance.