• Tunnel and Underground Space
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• v.27 no.5
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• pp.324-332
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• 2017

In this paper, a numerical analysis of one-dimensional viscous fluid flow in a rock joint using UDEC code is performed to evaluate the effect of design parameters on injection performance. We consider injection pressure, fluid compressibility, time dependence of yield strength and viscosity of injected grout fluid, and mechanical deformation of joint as the design parameters, and penetration length and flow rate of injection are investigated as the injection performance. Numerical estimations of penetration length and flow rate were compared to analytical solution and were well comparable with each other. We showed that cumulative injection volume can be over-estimated by 1.2 times than the case that the time-dependent viscosity evolution is not considered. We also carried out a coupled fluid flow and mechanical deformation analysis and demonstrated that injection-induced joint opening may result in the increment of cumulative volume by 4.4 times of that from the flow only analysis in which joint aperture is kept constant.

• The Korean Journal of Pain
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• v.19 no.2
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• pp.181-186
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• 2006

Background: Although cervical epidural block can be a useful therapeutic treatment for head, neck and upper extremities pain, there is no consensus regarding the volume of injection required for pain management. Herein, the spreading in the vertebral segments after a cervical epidural injection of either a 5 or 10 ml volume was studied. Methods: A total of 78 patients, suffering from head, neck and upper extremity pain, were selected. Cervical epidural blocks were performed consecutively with 5 ml (n = 42) and 10 ml (n = 36) of 0.4% mepivacaine and 222 mg I/ml iopamidol at the C7⁣-T1 levels. Both anteroposterior (AP) and lateral radiographs were obtained under fluoroscopy, and the upper and lower epidural spreading of the contrast media in relation to the vertebral level was evaluated. Results: The cervical epidural blocks were performed without complications. The rostral spreading of the contrast media in the vertebral segments in groups 1 and 2 were $5.6{\pm}1.1$ and $6.1{\pm}1.1$, respectively. The caudal spreading of the contrast media in the vertebral segments in groups 1 and 2 were $5.4{\pm}3.4$ and $7.2{\pm}3.9$, respectively. The total numbers of segments with vertebral spreading of the contrast media in both directions showed significant differences between the two groups. The numbers of patients who showed spreading of the contrast media up to C2 vertebral segment showed no significant differences between the two groups. Conclusions: 5 and 10 ml epidural injection volumes may be adequate for the spread of contrast media to the entire cervical spine. A 5 ml epidural injection volume, compared to a 10 ml volume, may be ample when considering the possibility of unnecessary caudal spreading of drugs and volume related complications in the management of head, neck and upper extremity pain.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1101-1110
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• 1998

Computational investigation was conducted to examine the performance of a high pressure common-rail fuel injection system which is used to power a passenger car direct injection (Dl) diesel engine. The pipe flows were modeled by one dimensional wave equation and solved by implicit FDM Each volume of injector was considered as chambers with orifice nozzle in connections. These simulation results were compared with the experimental data of Ganser Hydromag. The comparison of needle life and rate of injection between simulation data and experimental data showed quite a good agreement Different shape of injection rate can be made by adjusting the size of inlet orifice and exit orifice in the piston chamber The pilot injection was accomplished by adjusting command signal.

• Journal of Hydrogen and New Energy
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• v.26 no.3
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• pp.287-293
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• 2015

The current study has investigated the effects of biodiesel blended with gasoline on the spray characteristics in a Constant Volume Combustion Chamber (CVCC). With the concentration of 5, 10, 15 and 20% by volume, biodiesel was blended with commercial gasoline and performed on the macroscopic visualization test. Pure gasoline and biodiesel were also tested as the reference. The shadowgraph technique was conducted in the constant volume chamber. The spray images were recorded by a high speed video camera with frame speed 10,000 frame per second. Fuel injection was set at 800, 1000 and 1,350 bar with the simulated speed 1,500 and 2,000 rpm. The back pressure was controlled at 20 bar. The spray angle and penetration tip were measured and analyzed by using the image processing. At the high injection pressure, the spray penetration length with the simulated speed 1,500 rpm showed that B100 was lower than GB00-20 whereas the spray penetration length with the simulated speed 2,000 rpm exhibited that GB blends and B100 were insignificantly different. Due to biodiesel concentration, its effects on spray angles were observed throughout injection periods (T1, T2 and T3). At the simulated speed 1,500 rpm, the spray angle of GB blends and B100 presented the same pattern following injection timing. In addition, when the simulated speed increased to 2,000 rpm the different spray angle of all blends disappeared at main injection (T3).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.787-791
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• 1996

In injection molding, location of gates have great influence on the quality of plastic parts. Usually, they are located by releated trial and errors of experienced mold designers. In this topic we will present the numerical algorithm for finding the optimal gate locations. Optimization algorithm is devided into two stages. In the first stage, candidated optimal gate locations can be found by geometry of part only; whereas in the next step, more acculate gate locations are selected byiterative computation with optimization part and analysis part. So from the following study, we suggested the modified flow-volume method, which will define the optimal gate locations in injection mold design.

• Nuclear Engineering and Technology
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• v.29 no.1
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• pp.58-67
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• 1997

A numerical study has been peformed to investigate the flow and mixing characteristics of a chemical injection tank in the chemical and volume control system (CVCS) of Yonggwang 5&6 (YGN 5&6). This study was undertaken to provide a basis for modification of the previous design (YGN 3&4) which gave a lot of difficulties in installation and operation of the chemical injection system during the start-up test because it needs a special reciprocating pump with a high actual head. For the tank of length-to-diameter ratios (L/D) of 1,2 and 3, each with and without a baffle inside, calculation results were obtained by solving the unsteady laminar two-dimensional elliptic forms of governing equations for the mass, momentum and species concentration. Finite-difference method was used to obtain discretized equations, and the SIMPLER solution algorithm, which was developed based on the staggered grid control volume, was employed for the calculation procedure. Results showed that the baffle is very effective in enhancing the mixing in the tank and that a baffle should be installed near the tank entrance in order to 110 chemicals into the reactor coolant system (RCS) within the operating time required.

• Analytical Science and Technology
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• v.36 no.1
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• pp.1-11
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• 2023

A new, sensitive, and reliable flow injection methodology was investigated for the determination of lead ion (II) in vegetables' samples using a laboratory-prepared reagent 2-[(6-methoxy-2-benzothiazoly)azo]-4-methoxy phenol (6-MBTAMP). Infrared spectroscopy, UV-visible spectrophotometry, Energy dispersive X-ray spectroscopy (EDX), Elemental Analysis (CHN), nuclear magnetic resonance spectroscopy ¹HNMR, and ¹³CNMR techniques were used to characterize the reagent and lead (II) complex. The method is based on lead ion (II) reacting with the reagent (6-MBTAMP) in a neutral solution to produce a green-red complex with a maximum absorbance at 670 nm. The optimum conditions, such as flow rate, lead ion (II) volume, reagent volume, medium pH, reagent concentration, and reaction coil length were thoroughly examined. The limits of detection (LOD) and quantification (LOQ) were determined to be 0.621 mg·L^-1 and 2.069 mg·L^-1 , respectively, while Sandell's sensitivity was determined to be 0.345 ㎍·cm^-2.

• Journal of Environmental Science International
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• v.32 no.7
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• pp.483-492
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• 2023

In this study, the treatment of livestock wastewater using an aerobic granular sludge based sequencing batch reactor was investigated. The reactor operation was carried out by general injection and split injection methods. The average removal efficiency of organic matter after the adaptation period was 71.5 and 87.4%, respectively. Some untreated organic matter was attributed to recalcitrant organic matter. The average removal efficiency of total nitrogen was 65.6 and 88.4%, respectively. These results indicate that the denitrification reaction by split injection was carried out smoothly. As for the solids, the ratio of aerobic granular sludge/mixed liquor suspended solid can be determined as the main factor of the process operation, and the ratio increased gradually and finally reached 86.0%. Correspondingly, the sludge volume index (SVI) was also improved, reaching 54 mL/g at the end of operation, and it is believed that the application of a short settling time contributed to the improvement of settleability.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.148-158
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• 1995

This paper describes a hierarchical structure for feature definition and classification, and feature representation method based on frame structure for process planning of prismatic machined components of injection mold. The concept of Volume Removal Directions and Vertical Faces is proposed to develop a method to define and to classify features for components of injection mold systematically. A method for classifying features by the combination of volume removal directions and vertical faces is developed, and also a feature representation method by using frame structure to represent design and manufacturing information is presented.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2965-2970
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• 2008

Effects of split injection and oxygen-enriched air on soot emissions in a DI diesel engine were studied by the KIVA-3V code. When split injection is applied, the second injection of fuel into a cylinder results in two separate stoichiometric zones which increases soot oxidation. As a result, soot emissions are decreased with split injection. When oxygen-enriched air is applied together with split injection, higher concentration of oxygen helps secondary combustion which results in a higher temperature in the cylinder. The increased temperature promotes growth reaction of acetylene with soot but doesn't improve the acetylene formation during the second injection of fuel. As more acetylene is consumed in the growth reaction of acetylene, the net acetylene mass in the cylinder is decreased, which leads to a decrease of soot formation. With an increase of soot oxidation caused by split injection, the soot emissions are decreased significantly. However, to avoid excessive NOx emissions with increased oxygen concentration, the level of oxygen concentration should be lower than 22% in volume.