• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.5-13
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• 2007

The performance of innovative prestressed support (IPS) earth retention system applied in soft clay was investigated and presented. The IPS wale system provides a high flexural stiffness to resist the bending by lateral earth pressure, and transfers lateral earth pressure to strut supports. The IPS wale system provides a larger spacing of support than conventional braced and anchored systems. The IPS earth retention system was selected for temporary earth support in a building construction in North Busan area. The excavation was made 28.8 m wide, 52.0 m long, and 16.1 m deep through loose fill to soft clay. The IPS system consists of 650 mm thick slurry walls, and five levels of IPS wales and struts. Field monitoring data were collected including wall deflections at six locations, ground water levels at four locations, IPS wale deflections at thirty locations, and axial loads on struts at twenty locations, during construction. The IPS earth retention system applied in soft clay performed successfully within a designed criterion. Field measurements were compared with design assumptions of the IPS earth retention system. The applicability and stability of the IPS earth retention system in soft clay were investigated and evaluated.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.355-362
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• 2009

The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, hydroxyl functionalized oxovanadium(IV) Schiff-base; N,N'-bis(4-hydroxysalicylidene)-ethylene-1, 2-diamineoxovanadium(IV), [VO($(OH)_2$-salen)]; has been covalently anchored on modified MWNTs. The new modified MWNTs ([VO($(OH)_2$-salen)]-MWNTs]) have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), UV-Vis, Diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The analytical data indicated a composition corresponding to the mononuclear complex of tetradentate Schiff-base ligand. The characterization of the data showed the absence of extraneous complex, retention of MWNTs and covalently anchored on modified MWNTs. Liquid-phase oxidation of cyclohexane with $H_2O_2$ to a mixture of cyclohexanone, cyclohexanol and cyclohexane-1,2-diol in $CH_3$CN have been reported using oxovanadium(IV) Schiff-base complex covalently anchored on modified MWNTs as catalysts. This catalyst is more selective toward cyclohexanol formation.

• Journal of Dairy Science and Biotechnology
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• v.23 no.2
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• pp.115-123
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• 2005

Microcapsules consisting of natural, biodegradable polymers for controlled and/or sustained core release applications are needed. Physicochemical properties of whey proteins suggest that they may be suitable wall materials in developing such microcapsules. The objectives of the research were to develop water-insoluble, whey protein-based microcapsules containing a model water-soluble drug using a chemical cross-linking agent, glutaraldehyde, and to investigate core release from these capsules at simulated physiological conditions. A model water soluble drug, theophylline, was suspended in whey protein isolate (WPI) solution. The suspension was dispersed in a mixture of dichloromethane and hexane containing 1% biomedical polyurethane. Protein matrices were cross-linked with 7.5-30 ml of glutaraldehyde-saturated toluene (GAST) for 1-3 hr. Microcapsules were harvested, washed, dried and analyzed for core retention, microstructure, and core release in enzyme-free simulated gastric fluid (SGF) and simulated intestinal fluid(SIF) at $37^{\circ}C$. A method consisting of double emulsification and heat gelation was also developed to prepare water-insoluble, whey protein-based microcapsules containing anhydrous milkfat (AMF) as a model apolar core. AMF was emulsified into WPI solution (15${\sim}$30%, pH 4.5-7.2) at a proportion of 25${\sim}$50%(w/w, on dry basis). The oil-in-water emulsion was then added and dispersed into corn oil ($50^{\circ}C$) to form an O/W/O double emulsion and then heated at $85^{\circ}C$ for 20 min for gelation of whey protein wall matrix. Effects of emulsion composition and pH on core retention, microstructure, and water-solubility of microcapsules were determined. Overall results suggest that whey proteins can be used in developing microcapsules for controlled and sustained core release applications.

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4018-4030
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• 2024

The in-vessel retention through external reactor vessel cooling (IVR-ERVC) strategy is a key management strategy for early termination of a nuclear severe accident that can threaten the integrity of the reactor vessel. To simulate the physical phenomena of the molten corium, the smoothed particle hydrodynamic (SPH) method is utilized in this study. The SPH method is a Lagrangian computational fluid dynamic (CFD) method that can simulate multi-fluid stratification, turbulence, natural circulation, radiative heat transfer, thermal ablation, and crust formation. To address the external vessel cooling, it is coupled with a conventional 1-D nuclear system analysis method. The 1-D system analysis code can calculate the two-phase natural circulation of cooling water and the convective heat transfer on the external reactor vessel wall. These two simulation codes exchange the temperature and heat flux of the reactor vessel outer wall. This study numerically simulated the IVR-ERVC strategy for a Korean high-power reactor and compared it with the traditional lumped parameter method (LPM). Unlike LPM, this study provides localized detailed data about the thermal hydraulic behavior of molten corium and visualization of phenomena in the IVR-ERVC strategy. This enhances our understanding of the phenomena in IVR-ERVC strategy and introduces new perspectives.

• Fisheries and Aquatic Sciences
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• v.14 no.1
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• pp.62-69
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• 2011

The effects of actively stimulating devices (ASD) on juvenile flatfish escape were studied to increase escape rates from the cod end by encouraging fish to approach the net wall. Two kinds of ASD were designed: a fluttering net panel, i.e., a free-end flag-like net panel, and a double conical rope array. Escape responses of juvenile bastard halibut were observed in a circulating water channel using two model cod ends, one made with diamond-shaped 43-mm-mesh-size polyethylene (PE) as a high-contrast cod end and the other with polyamid (PA) mono-ply as a low-contrast cod end. Retention rate was significantly lower with the double conical rope-array ASD in the PE cod end than with conventional PE cod ends only or the fluttering net-panel ASD inside the PE cod end. Mean retention rate with the low-contrast PA cod end was also significantly lower than that with the high-contrast PE conventional cod end. Therefore, active fluttering devices using a double conical rope array together with less visible low-contrast netting in the cod end could help to reduce the bycatch of juvenile flatfish by weakening their optomotor response and actively driving fish to the side net panel.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.9
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• pp.1219-1227
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• 2000

Rumination behavior, in vivo digestibility of cell wall constituents, particle size reduction in the rumen, and retention time in the digestive tract of sheep were examined using rice and oat straw as roughage sources. The in sacco digestibility, rumen fermentation, and microbial population and internal adenosine 5-triphosphate (ATP) content were also determined under feeding conditions of high-roughage and high-concentrate diets. Chewing number and time in rumination behavior were higher with rice straw than with oat straw, while the in sacco and in vivo DMD of rice straw were consistently lower than those of oat straw. Rice straw also showed higher frequency of thinner and longer particles in the rumen contents and lower retention time in the whole digestive tract as compared to those of oat straw. Rice straw was more effective to maintain the ruminal pH than oat straw, being reflected in higher internal ATP content of large-type protozoa on the high- concentrate diet. Changes in the ruminal microflora by shifting from the low- to the high- concentrate diet were also different between rice and oat straw.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.726-731
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• 2005

Sedimentation is treated as the most important unit process in waterworks, and plays great role on turbidity removal efficiency. Rectangle sedimentation basin is the most widely accepted sedimentation process. But it has some problems with short-circuit flow and density flow caused by temperature and influent turbidity variation. To solve these problems, installation of rectification wall was suggested, but not generally fully accepted in field. Because hole of rectification wall cause jet flow. In this research, use of moving baffle was investigated. Moving baffle was designed to induce uniform velocity at every section of water flow. The baffle walls was made from soft fiber materials. The baffle walls with flow of sedimentation basin moves at same speed. It is like that it controls density flow and short-circuit flow and induce uniform velocity at every section of water flow in sedimentation basin. When moving baffle was operated retention time of sedimentation basin was extended to 1 hours. When it talked again and the effluent time of highest concentration of the chlorine ion from 100 minutes was extended to 160 minutes. Turbidity removal efficiency was tested with different operation modes(continuous and batch) with influent turbidity and retention time. It was revealed that turbidity removal efficiency carl be improved up to 36%(continuous mode) and 58%(batch mode) respectively. Consequently if moving baffle introduces in Rectangle sedimentation basin, it forecasts that the turbidity improvement above 30% will be possible.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.654-659
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• 2002

To investigate the effects of preparation conditions of encapsulating ester compounds on retention rate of core material in microcapsules prepared with sea tangle alginate, the amounts of ester compounds migrated gelling solution (1 M $CaCl_2$) and washing water from microcapsules that were prepared by adding kinds of ester compound, by controlling ratios of emulsifier to ester compounds and by differing ratios of alginates (wall material) to ester compounds (core material) were measured. Also the amount of ester compounds retained in microcapsules was measured. The higher weight molecular of ester compounds were, the lower amounts of ester compounds migrated gelling solution and washing water from microcapsules were, But its amounts retained in microcapsules were increased, The changes of ethyl caprylate amount migrated gelling solution and washing water from microcapsules prepared by increasing ratios of emulsifier to ethyl caprylate were little, but its half-lives in microcapsules during storage at 25$^{\circ}C$ were steeply increased. Increasing ratios of wall material to core material, ethyl caprylate amount migrated gelling solution and washing water from microcapsules showed 1.8$\~$$2.0\%$ and 2.9$\~$$3.5\%$ respectively but half-lives of ethyl caprylate retained in alginate microcapsules were increased.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.419-427
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• 1992

The performance of homemade thermal field-flow fractionation (ThFFF) and the optimization for separation are investigated in terms of retention parameters and selectivity using polystyrene standards. The ribbonlike channel was constructed by sandwiching two Mylar spacers between two highly polished copper bars which serve as channel walls. The hot bar was heated by two electrical cartridge heaters and the cold bar had holes through the entire length, allowing tap water as coolant to enter. It has been observed that the retention of polystyrenes increases as the temperature gradient increases. And the retention decreases as the cold wall temperature increases from 20 to $45^{\circ}C$. In comparison with size exclusion chromatography, ThFFF is more selective but has relatively low efficiency. It has been found that the plate height is proportional to the flow velocity and good estimates of polydispersities can be made directly from the ThFFF data.

• Journal of the Korean Society of Radiology
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• v.85 no.2
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• pp.363-371
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• 2024

Purpose Acute cholecystitis is a complication of transarterial chemoembolization (TACE) that occasionally requires surgical intervention. We aimed to analyze the incidence and risk factors of cholecystitis requiring surgical intervention in patients with embolic material uptake on cone beam CT (CBCT) performed immediately after various TACE procedures. Materials and Methods After a retrospective review of 2633 TACE procedures performed over a 6-year period, 120 patients with embolic material retention in the gallbladder wall on CBCT immediately after TACE were selected. We analyzed the incidence of and risk factors for acute cholecystitis. Results The overall incidence of acute cholecystitis requiring surgical intervention was 0.45% (12 of 2633 TACE procedures); however, it was present in 10% (12 of 120) of procedures that showed high-density embolic material retention in the gallbladder wall on CBCT performed immediately after TACE. Acute cholecystitis requiring surgical intervention occurred in eight patients (66.7%) who underwent direct cystic arterial embolization. Surgical intervention was performed 15 days (mean) after TACE. Conclusion Most unintended chemolipiodol deposits in the gallbladder wall resolved without intervention or surgery. However, superselective direct cystic arterial chemoembolization was associated with a high incidence of acute cholecystitis requiring surgery, and patients who undergo this procedure should be closely monitored.