• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.154-159
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• 2004

A new microflow rate controller for medical injection was developed and evaluated. The flow rate was controlled by changing the friction depth as well as the friction length of the micro-channel. A precise micro-fabrication of the micro-channel was requested for an accurate flow control. The friction depth was inversely proportional to the friction length, which gives a linear flow control to the channel length. The channel groove was fabricated with a plastic material. A rubber containing silicone oil was covered over the groove, which satisfies both lubrication and leakage prevention. The flow controller was validated by performing the numerical simulation and experiment. A good agreement was shown between computation and experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.7
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• pp.94-103
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• 1999

A model for the prediction of combustion and exhaust emissions of DI diesel engine has been formulated and developed . This model is a quasi-dimensional phenomenological one and is based on multi-zone combustion modelling concept. It takes into consideration, on a zonal basis ,detailed of fuel spray formation, droplet evaporation, air-fuel mixing, spray wall interaction, swirl , heat transfer, self ignition and burning rate . The emission model is considered with chemical equipment , as well as the kinetics of fuel. NO and soot reactions in order to calculate the pollutant concentrations within each zone and the whole of cylinder . The accuracy of prediction versus experimental data and the capability of the model in predicting engine heat release, cylinder pressure and all the major exhaust emissions on zonal and cumulative basis., is demonstrated. Detailed prediction results showing the sensitivity of the model bv various injection rates are presented and discussed.

• Journal of the Korean Institute of Plant Engineering
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• v.23 no.4
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• pp.29-38
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• 2018

Through process quality information, the time required for process quality analysis has been drastically shortened, the process defect rate has been reduced, and the manufacturing lead time has been shortened and the on-time delivery rate has been improved. Therefore, The purpose of this study is to develop a quality information analysis system model that effectively shortens the time required for process quality analysis in automobile safety belt parts manufacturing process. As a result of experiments on communication operation between manufacturing execution system (MES) quality server, injection machine control computer, injection machine programmable logic controller (PLC) and terminal, in analyzing quality information, the conventional handwriting input method took an average of 20 minutes, but the new multi-network method took about 2 minutes on average. In addition, the process defect rate was reduced by 13% and the manufacturing lead time was shortened from 28 hours to 20 hours. The delivery compliance rate improved from 96 to 99%.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.25-32
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• 2013

Biodiesel is technically competitive with it and offers technical advantages over conventional petroleum diesel fuel. Biodiesel is an environment friendly alternative liquid fuel that can be used in any diesel engine without modification. In this study, (dP/dCA)max and heat release, emission characteristics with different fuel injection timings are compared between diesel fuel and biodiesel in the D.I. diesel engine with T/C. The engine was operated at five different fuel injection timings from BTDC 6deg to 14deg at 2deg intervals and with four different loads at engine speed of 1800rpm. The experiments in a test engine showed that ranges between low and high of (dP/dCA)max got narrower, as the engine load increased, BD blend rate increased, and fuel injection timing was delayed. Cumulative heat release increased with the advanced fuel injection timing. NOX emissions decreased with the delays of fuel injection timing.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.165-176
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• 1996

The flow field and spray characteristics for loop scavenged type 2stroke engine having pancake shape was numerically computed using KIVA-Ⅱ code. The cylinder has 1intake port, 2side intake ports and 1exhaust port with induced flow angle 25 deg. In engine calculation, the chop techniques is used to strip or add planes of cells across the mesh adjacent to the TDC and the BDC(ports parts) for preventing the demand of exceed time during the computation, providing a control on cell height in the squish region. The modified turbulent model including the consideration of the compressibility effect due to the compression and expansion of piston was also used. The case of 25 deg.(injection angle) which is opposite to scavenging flow direction shows better the distribution of droplets and the evaporation rate of droplets compared to other cases(0 deg., - 25 deg.). When injection pressure was increased, the spray tip penetration became longer. When injection pressure was increased, the interaction between the upward gas velocity and spray droplets strongly cause. Thus the breakup of droplets is strongly occurred and the evaporation rate of droplets was found to be better.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.128-136
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• 2007

It is well known that two representative methods satisfy EURO-IV regulation from EURO-III. The first method is to achieve the regulation through the reduction of NOx in an engine by utilizing relatively high EGR rate and the elimination of subsequently increased PM by DPF. However, it results in the deterioration of fuel economy due to relatively high EGR rate. The second is to use the high combustion strategy to reduce PM emission by high oxidation rate and trap the high NOx emissions with DeNOx catalysts such as Urea-SCR. While it has good fuel economy relative to the first method mentioned above, its infrastructure is demanded. In this paper, the number distribution of nano PM has been evaluated by Electrical Low Pressure Impactor(ELPI) and CPC in case of Urea-SCR system in second method. From the results, the particle number was increased slightly in proportion to the amount of urea injection on Fine Particle Region, whether AOC is used or not. Especially, in case of different urea injection pressure, the trends of increasing was distinguished from low and high injection pressure. As low injection pressure, the particle number was increased largely in accordance with the amount of injected urea solution on Fine Particle Region. But Nano Particle Region was not. The other side, in case of high pressure, increasing rate of particle number was larger than low pressure injection on Nano Particle Region. From the results, the reason of particle number increase due to urea injection is supposed that new products are composited from HCNO, sulfate, NH3 on urea decomposition process.

• Journal of Embryo Transfer
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• v.25 no.3
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• pp.133-139
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• 2010

The purpose of this study was to determine the relationship between conception rate and other parameters (body condition score; BCS, progesterone concentrations and follicle size) before estrus induction with $PGF_2{\alpha}$. The conception rate in cows with (2.75, 2.75 to 3.25 and 3.25), BCS regardless of AI (artificial insemination) time was 47.5, 67.5% and 48.5% at $PGF_2{\alpha}$ injection, respectively. The conception rate regardless of BCS was 59.0% in cows inseminated based on detected estrus, and 46.2% in cows inseminated at 72 to 80 hours (timed artificial insemination, TAI) after $PGF_2{\alpha}$ injection. The conception rate regardless of AI time was 43.0% in cows with low progesterone concentrations (less than 1.0 ng/ml), and 67.5% in cows with high progesterone concentrations (more than 1.0 ng/ml) at $PGF_2{\alpha}$ injection. The conception rate regardless of progesterone concentrations was 59.9% in cows inseminated based on detected estrus, and 48.1% in cows of TAI after $PGF_2{\alpha}$ injection. The conception rate regardless of AI time was 36.0% in cows with small dominant follicles (less than 5 mm), 56.0% in cows between 5 mm to 10 mm of follicle size, and 65.5% in cows with large dominant follicles (more than 10 mm) at $PGF_2{\alpha}$ injection, respectively. The conception rate regardless of follicle size was 57.3% in cows inseminated based on detected estrus, and 47.6% in cows of TAI after $PGF_2{\alpha}$ injection. These results indicated that if the cows with BCS 2.75 to 3.25, active corpus luteum, and/or large dominant follicle (more than 10 mm) are used for estrus induction, the conception rate will be greater.

• Korean Journal of Radiology
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• v.2 no.1
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• pp.28-36
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• 2001

Objective: To provide a systematic overview of the effects of various parameters on contrast enhancement within the same population, an animal experiment as well as a computer-aided simulation study was performed. Materials and Methods: In an animal experiment, single-level dynamic CT through the liver was performed at 5-second intervals just after the injection of contrast medium for 3 minutes. Combinations of three different amounts (1, 2, 3 mL/kg), concentrations (150, 200, 300 mgI/mL), and injection rates (0.5, 1, 2 mL/sec) were used. The CT number of the aorta (A), portal vein (P) and liver (L) was measured in each image, and time-attenuation curves for A, P and L were thus obtained. The degree of maximum enhancement (Imax) and time to reach peak enhancement (Tmax) of A, P and L were determined, and times to equilibrium (Teq) were analyzed. In the computed-aided simulation model, a program based on the amount, flow, and diffusion coefficient of body fluid in various compartments of the human body was designed. The input variables were the concentrations, volumes and injection rates of the contrast media used. The program generated the time-attenuation curves of A, P and L, as well as liver-to-hepatocellular carcinoma (HCC) contrast curves. On each curve, we calculated and plotted the optimal temporal window (time period above the lower threshold, which in this experiment was 10 Hounsfield units), the total area under the curve above the lower threshold, and the area within the optimal range. Results: A. Animal Experiment: At a given concentration and injection rate, an increased volume of contrast medium led to increases in Imax A, P and L. In addition, Tmax A, P, L and Teq were prolonged in parallel with increases in injection time The time-attenuation curve shifted upward and to the right. For a given volume and injection rate, an increased concentration of contrast medium increased the degree of aortic, portal and hepatic enhancement, though Tmax A, P and L remained the same. The time-attenuation curve shifted upward. For a given volume and concentration of contrast medium, changes in the injection rate had a prominent effect on aortic enhancement, and that of the portal vein and hepatic parenchyma also showed some increase, though the effect was less prominent. A increased in the rate of contrast injection led to shifting of the time enhancement curve to the left and upward. B. Computer Simulation: At a faster injection rate, there was minimal change in the degree of hepatic attenuation, though the duration of the optimal temporal window decreased. The area between 10 and 30 HU was greatest when contrast media was delivered at a rate of 2 3 mL/sec. Although the total area under the curve increased in proportion to the injection rate, most of this increase was above the upper threshould and thus the temporal window was narrow and the optimal area decreased. Conclusion: Increases in volume, concentration and injection rate all resulted in improved arterial enhancement. If cost was disregarded, increasing the injection volume was the most reliable way of obtaining good quality enhancement. The optimal way of delivering a given amount of contrast medium can be calculated using a computer-based mathematical model.

• Korean Journal of Materials Research
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• v.12 no.1
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• pp.68-74
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• 2002

The lead has to be removed for the recycling of copper alloy. The lead cannot be removed from the copper alloy by oxidation. It can be removed by the evaporation because of its high vapor pressure. However, rare information is found on removal of lead from copper alloy. The purpose of present work is to provide a fundamental knowledges on the removal of lead from the copper alloy by evaporation. Gas injection was made in molten copper alloy, and the evaporation rate of lead was measured. The influence of Ar gas flow rata(2~4 L/min), initial contents of lead(2~4wt%Pb), temperature(1200~140$0^{\circ}C$) was investigated based on the thermodynamic and the kinetics. The rate constant is increased with increasing flow rate of Ar and temperature. Though amount of lead removed is increased with higher initial lead concentration, the rate constant is not changed significantly. The activation energy is estimated from the temperature dependence of the rate constant. Also removal of lead from the copper by adding chloride was made for the comparison.

• The Journal of Engineering Geology
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• v.32 no.3
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• pp.389-399
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• 2022

Observations on the influence of the fluid infiltration on the breakdown pressure during laboratory hydraulic fracturing tests, along with an analysis of the applicability of the breakdown pressure prediction for cylindrical samples using Quasi-static and Linear Elastic Fracture Mechanics approaches were carried out. These approaches consider fluid infiltration through the so-called radius of fluid infiltration or crack radius, a parameter that is not a material property. Two sets of tests under pressurization rate controlled and injection rate controlled tests were used to evaluate the applicability of these methods. The difficulty of the estimation of the radius of fluid infiltration was solved by back calculating this parameter from an initial set of tests, and later, the obtained relationships were used to predict breakdown pressures for a second set of tests. The results showed better predictions for the injection rate than for the pressurization rate tests, with average errors of 3.4% and 18.6%, respectively. The larger error was attributed to differences in the testing conditions for the pressurization rate tests, which had different applied vertical pressures. On the other hand, for the tests carried out under constant injection rate, the Linear Elastic Fracture Mechanics solution reported lower errors compared to the Quasi-static solution, with values of 3% and 3.8%, respectively. Moreover, a sensitivity analysis illustrated the influence of the radius of fluid penetration or crack radius and the tensile strength on the breakdown pressure, suggesting a need for a careful estimation of these values. Then, the calculation of breakdown pressure considering fluid infiltration in cylindrical samples under triaxial conditions is possible, although larger data sets are desirable to validate and derive better relations.