• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1064-1074
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• 1992

Eliminating the under-cut caused by interference between a mold and a product in designing a mold for in jection molding processes is a very important problem. In general, the under-cut problem can be avoided by side cores which are the principal members of a mold assembly. In this research, a procedure has been developed by which the side cores and the corresponding core and cavity plates of a mold are generated after identifying the mold faces preventing product faces from moving while being discharged. The characteristic features of the procedure suggested in this paper are as follows. One is that the interference faces between the product and the mold are derived only from the core plate(or cavity plate) alone without considering the product together. The other is that the algorithm in the designing of side cores and modifying molds, is very efficient because it uses Euler operations instead of Boolean operations.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.918-929
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• 2015

Microbial enhanced oil recovery (MEOR) is being used more widely, and the biological contributions involved in MEOR need to be identified and quantified for the improvement of field applications. Owing to the excellent interfacial activity and the wide distribution of producing strains in oil reservoirs, lipopeptides have proved to be an essential part of the complex mechanisms in MEOR. In this study, crude lipopeptides were produced by a strain isolated from an indigenous community in an oil reservoir. It was found that crude lipopeptides can effectively reduce the IFT (interfacial tension) to 10^-1~10^-2 mN/m under high salinity without forming stable emulsions, and the wettability of natural sandstone can be enhanced (Amott index, from 0.36 to 0.48). The results of core flooding experiments indicate that an additional 5.2% of original oil in place can be recovered with a 9.5% reduction of injection pressure. After the shut-in period, the wettability of the core, the reduction of injection pressure, and the oil recovery can be improved to 0.63, 16.2% and 9.6%, respectively. In the microscopic flooding experiments, the crude oil in membrane, cluster, and throat states contribute nearly 90% in total of the additional oil recovery, and the recovery of membranestate oil was significantly enhanced by 93.3% after shut in. Based on the results in macro and pore scale, the IFT reduction and the wettability alteration are considered primary contributors to oil recovery, while the latter was more dominant after one shut-in period.

• The Korean Journal of Physiology and Pharmacology
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• v.28 no.2
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• pp.145-152
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• 2024

Chemotherapy-induced cognitive impairment is recognized as the most typical symptom in patients with cancer that occurs during and following the chemotherapy treatment. Recently many studies focused on pharmaceutical strategies to control the chemotherapy side effects, however it is far from satisfactory. There may be a need for more effective treatment options. The aim of this study was to investigate the protective effect of exercise on cisplatin-induced neurotoxicity. Eight-week-old C57BL6 mice were separated into three group: normal control (CON, n = 8); cisplatin injection control (Cis-CON, n = 8); cisplatin with aerobic exercise (Cis-EXE, n = 8). Cisplatin was administered intraperitoneally at a dose of 3.5 mg/kg/day. The Cis-EXE group exercise by treadmill running (14-16 m/min for 45 min daily, 3 times/week) for 12 weeks. Compared to the CON group, the cisplatin injection groups showed significant decrease in body weight and food intake, indicating successful induction of cisplatin toxicity. The Cis-CON group showed significantly increased levels of pro-inflammatory cytokines including IL-6, IL-1β, and TNF-α in the hippocampus, while the Cis-EXE group was significantly decreased in the expression of IL-6, IL-1β, and TNF-α. In addition, compared to the CON group, the levels of synapse-related proteins including synapsin-1 and -2 were significantly reduced in the Cis-CON group, and there was a significant difference between the Cis-CON and Cis-EXE groups. Antioxidant and apoptosis factors were significantly improved in the Cis-EXE group compared with the Cis-CON group. This study suggest that exercise could be meaningful approach to prevent or improve cisplatin-induced cognitive impairment.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2367-2370
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• 2014

"Cat's eye"-shaped $[^{57}Co]CoO@SiO_2$ core-shell nanostructure was prepared by the reverse microemulsion method combined with radioisotope technique to investigate a potential imaging agent for a single photon emission computed tomography (SPECT) in nuclear medicine. The core cobalt oxide nanorods were obtained by thermal decomposition of $Co-(oleate)_2$ precursor from radio isotope Co-57 containing cobalt chloride and sodium oleate. The $SiO_2$ coating on the surface of the core cobalt oxide nanorods was produced by hydrolysis and a condensation reaction of tetraethylorthosilicate (TEOS) in the water phase of the reverse microemulsion system. In vivo test, micro SPECT image was acquired with nude mice after 30 min of intravenous injection of $[^{57}Co]CoO@SiO_2$ core-shell nanostructure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.140-152
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• 1989

The study on the penetration of sprays during the initial phase of injection period, i.e. ignition delay period, in high speed small D.I. diesel engines are strongly affected by such behavior. To investigate the penetration of the sprays injected through single cylinderical orifice, a mathematical model was developed and compared with experimental results. In this model, radial heterogeneity of fuel density in the spray, transiency of injection pressure difference, and spray outrunning phenomenon were considered simultaneously. Experiments on the behaviors of sprays in the high pressure air chamber were conducted at various injection pressure differences and different levels of back air pressure. The behaviors of sprays injected into the chamber through the conventional Bosch injection pump were visualized with side stroboscopic illumination. Comparison of the experimental results with predictions from the mathematical model confirmed the validity of the model. It was also found that during the initial phase of the injection period the penetration of sprays vs. time appeared to have two transition points; one corresponded to disintegration point of liquid fuel jet, the other to the beginning of steady state injection.

• Tunnel and Underground Space
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• v.26 no.3
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• pp.166-180
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• 2016

The present study numerically simulated the CO2 injection into the saline aquifer of CO2CRC Otway pilot project and the resulting hydrological-mechanical coupled process in the storage site by TOUGH-FLAC simulator. A three-dimensional numerical model was generated using the stochastic geological model which was established based on well log and core data. It was estimated that the CO2 injection of 30,000t over a period of 200 days increased the pressure near the injection point by 0.5 MPa at the most. The pressure increased rapidly and tended to approach a certain value at an early stage of the injection. The hydrological and mechanical behavior observed from the CO2 flow, effective stress change and stress-strength ratio revealed that the CO2 injection into the saline aquifer under the given condition would not have significant effects on the mechanical safety of the storage site and the hydrological state around the adjacent fault.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.325-334
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• 2003

It is very difficult to rehabilitate the damaged earth dam core to manage it stably against development of flow path and increase of leakage by hydraulic fracture. In this study, application of CGS (Compaction Grouting System) to damaged earth dam core was noticed by analyzing and comparing the results of the in-situ data and FEM. Results of in-situ data showed that according as progress of rehabilitation works tip pressures increased and volume of injection decreased, voids of damaged dam core were filled with materials similar to origin dam core. Rehabilitations caused turbidity and volume of leakage to decrease at the same water level. Also, results of FEM analysis indicated that permeability decreased by rehabilitation. Through this study, it is proved that CGS is able to decrease permeability coefficient, volume of leakage and turbidity on damaged earth dam core.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.973-979
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• 2024

In the framework of the Generation IV research and development project, in which the French Commission of Alternative and Atomic Energies (CEA) is involved, a main objective for the design of Sodium-cooled Fast Reactor (SFR) is to meet the safety goals for severe accidents. Among the severe ones, the Unprotected Transient OverPower (UTOP) accidents can lead very quickly to a global melting of the core. UTOP accidents can be considered either as slow during a Control Rod Withdrawal (CRW) or as fast. The paper focuses on fast UTOP accidents, which occur in a few milliseconds, and three different scenarios are considered: rupture of the core support plate, uncontrolled passage of a gas bubble inside the core and core mechanical distortion such as a core flowering/compaction during an earthquake. Several levels and rates of reactivity insertions are also considered and the thermal-mechanical behavior of an ASTRID fuel pin from the ASTRID CFV core is simulated with the GERMINAL code. Two types of fuel pins are simulated, inner and outer core pins, and three different burn-up are considered. Moreover, the feedback from the CABRI programs on these type of transients is used in order to evaluate the failure mechanism in terms of kinetics of energy injection and fuel melting. The CABRI experiments complete the analysis made with GERMINAL calculations and have shown that three dominant mechanisms can be considered as responsible for pin failure or onset of pin degradation during ULOF/UTOP accident: molten cavity pressure loading, fuel-cladding mechanical interaction (FCMI) and fuel break-up. The study is one of the first step in fast UTOP accidents modelling with GERMINAL and it has shown that the code can already succeed in modelling these type of scenarios up to the sodium boiling point. The modeling of the radial propagation of the melting front, validated by comparison with CABRI tests, is already very efficient.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.13-23
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• 2006

The sinkhole and leakage in dam core were detected at one of earth fill dams in Korea. The damage areas in the core of the dam were repaired by compaction grouting method. This study is to evaluate compaction grouting activity by in-situ and laboratory experiments before, during and after the remedial work. The intensive site investigation and geophysical survey were conducted during and after the compaction grouting work. The compaction grouting work was carried out for the damaged dam core between June 16 and August 24, 2000. The leakage reduction generally occurred in the core of the dam after the remedial work. The use of compaction grouting was considered the proper countermeasures for repairing the damaged dam. It shows that the loose or voided zones have been properly filled and the leakage has been reduced by about 96% of that before the treatment of the remedial work performed at dam core by compaction grouting.

• Korean Journal of Computational Design and Engineering
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• v.6 no.1
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• pp.9-16
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• 2001

Electrical discharge machining(EDM) is an important process of machining the injection mold. This paper includes efficient design processes of electrodes for EDM. Based on the solid modeler, electrodes can be created by boolean and offset operations with core/cavity models. The built-in offset operations of the solid modeler may occur unexpected results due to the limitations of the solid modeler. We proposed the multi-step and moving-face offset processes in order to apply the EDM clearances. The proposed design processes are implemented with Unigraphics Vl5 API functions and C language and tested on Windows NT 4.0.