• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.627-637
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• 1985

The combustion process and the performance of a diesel engine are seriously affected by the ignition delay period of the fuel used. Some methods for improving the combustion process in the engine cylinder are to well match the strength of air swirl with the space of sprays in the cylinder, to blend an ignition improver in the fuel, to inject a small amount of auxiliary fuel prior to main injection and so on. Recently, the improvement of fuel economy and the reduction of exhaust smoke and NO have been successfully achieved by supplying diesel engines with emulsified fuel. However, it is very difficult to know real combustion mechanism under such special conditions, because of many factors affecting on the combustion process in practical reciprocating engine. In the present paper, the combustion processes of diesel fuel and emulsion fuel were tried to improve and to observe by making contact with various lean pre-mixtures in the hot air stream duct. This hot air stream method has an advantage that the spontaneous combustion process can be observed under a simplified condition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.15-20
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• 2016

The grouting method, which can be used to effectively improve small areas within a short amount of time, may have different injection effects depending on the ground conditions and the levels of a water table. In particular, for ground with a relatively large permeability, the strength of the ground and the water proof ability can decrease over time due to the leaching process. To solve this problem, a "self-healing smart grouting (SSG) method", which was designed to maintain the initial strength of the ground by minimizing the leaching process, was developed recently. In this study, uniaxial compression tests were carried out on SSG samples to understand the strength of SSG over curing time where two different curing temperatures have been applied for comparison. The uniaxial compression strength of SSG was further compared with the samples prepared using conventional methods (LW and SGR). The test results showed that the uniaxial compression strength of SSG was higher at both high and low curing temperatures compared to that of the samples prepared using conventional methods. The initial strength of SSG was also relatively higher.

• The Korean Journal of Pain
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• v.23 no.4
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• pp.236-241
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• 2010

Background: Selective inhibitors of cycloosygenase (COX)-2 are commonly used analgesics in various pain conditions. Although their actions are largely thought to be mediated by the blockade of prostaglandin (PG) biosynthesis, evidences suggesting endogenous opioid peptide link in spinal antinociception of COX inhibitor have been reported. We investigated the roles of opioid receptor subtypes in the spinal antionociception of selective COX-2 inhibitor. Methods: To examine the antionociception of a selective COX-2 inhibitor, DUP-697 was delivered through an intrathecal catheter, 10 minutes before the formalin test in male Sprague-Dawley rats. Then, the effect of intrathecal pretreatment with CTOP, naltrindole and GNTI, which are ${\mu}$, $\delta$, and k opioid receptor antagonist, respectively, on the analgesia induced by DUP-697 was assessed. Results: Intrathecal DUP-697 reduced the flinching response evoked by formalin injection during phase 1 and 2 Naltrindole and GNTI attenuated the antinociceptive effect of intrathecal DUP-697 during both phases of the formalin test, CTOP reversed the antinociception of DUP-697 during phase 2, but not during phase 1, Conclusions: Intrathecal DUP-697, a selective COX-2 inhibitor, effectively relieved inflammatory pain in rats. The $\delta$ and $\kappa$ opioid receptors are involved in the activity of COX-2 inhibitor on the facilitated state as well as acute pain at the spinal level, whereas the ${\mu}$ opioid receptor is related only to facilitated pain.

• Journal of Pharmaceutical Investigation
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• v.38 no.1
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• pp.57-61
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• 2008

A HPLC-ELSD method was developed to determine saikosaponin derivatives from Bupleuri Radix. Eight saikosaponins, saikosaponin c, i, h, a, $b_2$, g, $b_1$ and d, were analyzed under optimized HPLC conditions [column: Eclipse XDB $C_{18}$ ($150{\times}4.6mm$ i.d., $5{\mu}m$; mobile phase: $H_2O$ with 0.1% $CH_3$COOH (v/v) for solvent A and AcCN with 0.1% $CH_3$COOH (v/v) for solvent B, gradient elution; flow rate: 1mL/min; injection volume: $20{\mu}L$]. Good linearity was achieved in the range from 62.5 to $250{\mu}g/mL$ for each compound, and intra-day precision and accuracy at each concentration level varied between 0.05 and 5.45% and between 93.9 and 109.6%, respectively, whereas those for inter-day variations were between 0.91 to 2.73% and 94.3 to 106.1%. This HPLC-ELSD method was applied for the determination of sakosaponins from Bupleuri Radix samples, and saikosaponin a $(0.79{\pm}0.20mg/g)$, c $(0.33{\pm}0.06mg/g)$ and d $(0.48{\pm}0.15mg/g)$ were observed as major compounds. The other saikosaponins were shown under limit of quantification level thus couldn't be quantified. The present study suggested that the introduced HPLC-ELSD method is selective and reliable, and not only saikosaponin a, but also saikosaponin c and d should be employed as the standard markers for Bupleuri Radix.

• Composites Research
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• v.25 no.4
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• pp.117-125
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• 2012

Warpage of the film insert molded (FIM) part is caused by an asymmetric residual stress distribution. Asymmetric residual stress and temperature distribution is generated by the retarded heat transfer in the perpendicular direction to the attached film surface. Since warpage was not prevented by controlling injection molding conditions, glass fiber (GF) filled composites were employed as substrates for film insert molding to minimize the warpage. Distribution of short GFs was evaluated by using micro-CT equipment. Proper models for micro mechanics, anisotropic thermal expansion coefficients, and closure approximation should be selected in order to calculate fiber orientation tensor and warpage of the FIM part with the composite substrate. After six kinds of micro mechanics models, three models of the thermal expansion coefficient and five models of the closure approximation had been considered, the Mori-Tanaka model, the Rosen and Hashin model, and the third orthotropic closure approximation were selected in this study. The numerically predicted results on fiber orientation tensor and warpage were in good agreement with experimental results and effects of GF reinforcement on warpage of the FIM composite specimen were identified by the numerical results.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.147-152
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• 2014

In this research, polysulfone hollow fiber membrane was used to recover $CO_2$ which is one of greenhouse gases from flue gas stream being emitted after the combustion of fossil fuels. The prerequisite requirement is to design the membrane process producing high-purity $CO_2$ from flue gas. For separation of $CO_2$, a membrane module and flue gas containing 10% carbon dioxide was used. The effects of operating conditions such as pressure, temperature, feed gas composition and multi-stage membrane on separation performance were examined at various stage cuts. Higher operating pressure and temperature increased carbon dioxide concentration and recovery ratio in permeate. Recovery ratio and separation efficiency increased if a higher content of $CO_2$ injection gas composition. Three-stage membrane system was producing a 95% $CO_2$ with 90% recovery from flue gas. The separation efficiency of three-stage membrane system was higher than one-stage system.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.984-991
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• 2008

This paper reports experimental results, demonstrating the feasibility of horseradish peroxidase(HRP) and H$_2$O$_2$ to reduce phenol transport in saturated porous media. A laboratory-scale packed column reactor(ID: 4.1 cm, sand-bed height 12 cm) column was utilized to simulate injection of HRP and H$_2$O$_2$ into an aquifer contaminated with phenol. Effluent concentrations of phenol and polymerization products were monitored before and after enzyme addition under various experimental conditions(enzyme dose: 0$\sim$2 AU/mL, [ionic strength]: 5$\sim$100 mM, pH: 5$\sim$9). The concentration of phenol in the column effluent was found to decrease by nearly 90% in the presence of HRP(2 AU/mL) and H$_2$O$_2$ in the continuous flow system at pH 7 and ionic strength 20 mM. The influent phenol was converted in the system to insoluble precipitate, which deposited in pore spaces. The remains were discharged as soluble oligomers. About 8% of total pore volume in column system was decreased by deposition of polymer produced.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.156-165
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• 2014

This paper is the first investigation on the effect of flow control methods on the part load performance in a spark ignition engine. For comparison of the methods, two control devices, port throttling and masking, were applied to a conventional engine without any design change of the intake port. Steady flow evaluation shows that steady flow rates per unit opening area and swirl ratio are very low compared with the port throttling and saturated from mid-stage valve lift, however, swirl increases slightly as the lift is higher in case of 1/4 masking control. In the part load performance, the effect of simple port throttling on lean misfire limit expansion is limited and insufficient; on the other hand a masking improves the limit considerably without any port modification for increasing swirl. Also the results show that the intake flow control improves the combustion with following two mechanisms: stratification induced by the combination of the flow pattern and the fuel injection timing attribute to ignition ability and the intensified flow ensure fast burn. In addition fuel consumption reduces under the flow controls and the reduction rate is different according to the operation conditions and control methods. At the Stoichiometric and/or low speed and low load the throttling method is more advantageous; however vice versa at lean and high load condition. Finally, the throttling is more efficient for HC reduction than masking, on the other side the NOx emissions increase under the masking and decrease under the port throttling compared with conventional port scheme.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.54-56
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• 2006

Single-well-gas-sparging tests were developed and evaluated for assessing the feasibility of in-situ aerobic cometabolism of trichloroethylene (TCE), using propane as a growth substrate. To evaluate transport characteristics of dissolved solutes [sulfur hexafluoride (SF6) or bromide (non-reactive tracers), propane (a growth substrate), ethylene, propylene (nontoxic surrogates to probe for CAH transformation activity), and DO], push-pull transport tests were performed. Mass balance showed about 90% of the injected bromide and about 80% of the injected SF6 were recovered, and the recoveries of other solutes were comparable with bromide and slightly higher than SF6. A series of Gas-Sparging Biostimulation tests were performed by sparging propane/oxygen/argon/SF6 gas mixtures, and temporal ground water samples were obtained from the injection well under natural gradient 'drift' conditions. The decreased time for propane depletion and the longer time to deplete SF6 as a conservative tracer indicate the progress of biostimulation. Gas-Sparging Activity tests were performed. .Propane utilization, DO consumption, and ethylene and propylene cometabolism were well demonstrated. The stimulated propane-utilizers cometabolized ethylene and propylene to produce ethylene oxide and propylene oxide, as cometabolic by-products, respectively. Gas-Sparging Acetylene Blocking tests were performed by sparging gas mixtures including acetylene to demonstrate the involvement of monooxygenase enzymes. Gas substrate degradation was essentially completely Inhibited in the presence of acetylene, and no production of the corresponding oxides was also observed. The Gas-Sparging tests supports the evidences that the successive stimulation of propane-oxidizing microorganisms, cometabolic transformation of ethylene and propylene by the enzyme responsible for methane and propane degradation.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.3
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• pp.580-584
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• 2008

In the present study, Radix clematidis extract (RCE) was evaluated to determine if it could protect pancreatic ${\beta}$ cells against multiple low dose streptozotocin (MLDS)-induced diabetes. Injection of mice with MLDS resulted in hyperglycemia and hypoinsulinemia, which was confirmed by immunohistochemical staining. However, the induction of diabetes by MLDS was completely prevented when mice were pre-administrated with RCE. Generation of oxidative stress is implicated in MLDS, a ${\beta}$ cell specific toxin-induced islet cell death. In this context, to elucidate the mechanisms of protective effects in RCE pre-administrated diabetic mice, we investigated the expression of heme oxygenase-1 (HO-1), which is one of the anti-oxidant enzymes. MLDS-induced HO-1 expressions were significantly reduced in MLDS-treated mice. However, the decrease of HO-1 by MLDS were protected by pretreatment of RCE. The molecular mechanism by which RCE inhibits diabetic conditions by MLDS appears to involve inhibition of HO-1 expression. Taken together, these results reveal the possible therapeutic value of RCE for the prevention of type 1 diabetes progression.