• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.76-84
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• 2001

Generally fuel injection system using solenoid have some problems between control signal and mechanical movement like as time lag. Main purpose of the present study is to help the design optimization of GDSI for real engine application. We have adopted two different solenoid driving circuit, namely saturation and pick-hold type and have investigated experimentally the current, needle force, needle opening duration and injection quantity. The pick-hold type driving circuit surpassed a saturation type in the response time and pression control of injection quantity. Accordingly, Using characterization data of operating factors such as time constant, driving force and so on, can be evaluated and adjusted to obtain an optimum injector performance.

• Journal of ILASS-Korea
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• v.3 no.1
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• pp.34-42
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• 1998

The correlation between the droplets size and the velocity are investigated for an intermittent spray of the pintle type fuel injector employed in a port injection gasoline engine. The analysis such as the mean droplet size, SMD, and velocity under the fixed injection period and varied fuel pressures are conducted utilizing PDPA systems. As results, the experimental data obtained, show that the larger droplet sizes. the higher velocities during the spray tip arrival time, and that at Z=70mm, r=8mm, both droplet sizes and velocities are peak. At the upstream, flow of droplets are dominated by injection pressure, which are more effected inertia force of droplets at the downstream of Z=70mm.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.561-567
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• 2014

Precision injection mold is an essential element in order to manufacture small and precision plastic lenses used for phone camera. There are many critical factors to meet the requested specifications of high quality plastic lenses. One of the main issues to realize high quality is minimizing decenter value, which becomes more critical as pixel numbers increases. This study suggests the method to minimize decenter value by modifying ejecting structure of the mold. Decenter value of injection-molded lens decreased to 1 ${\mu}m$ level from 5 ${\mu}m$ by applying suggested ejecting method. Also, we also developed BIS (Built-in Sensor) based smart mold system, which has pressure and temperature sensors inside of the mold. Pressure and temperature profiles from cavities are obtained and can be used for deduction of optimal injection molding condition, filling imbalance evaluation, status monitoring of injection molding and prediction of lens quality.

• Design & Manufacturing
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• v.11 no.1
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• pp.34-38
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• 2017

Deformation frequently occurring in injection molded products is a phenomenon displayed due to uneven shrinkage distribution and orientation of the whole molded product. Shrinkage deformation is a very serious problem because it causes deformation of the molded article and shortens the performance of the product. In this paper, we are focusing on the warpage of keypad in mobile phone. In other words, we focused on minimizing keypad deformation. In the study, the Taguchi method was applied to find the injection molding conditions that minimize the deformation of the keypad. In the case of this keypad, the main factors influencing the shrinkage deformation were predicted as the melting temperature, coolant temperature and cooling time. In addition, the optimum molding conditions were obtained and the shrinkage strain was minimized. Experiments for the Taguchi method and verification of optimal molding conditions were performed using an injection molding analysis program.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.2040-2052
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• 2005

The present paper centers on the establishment of a quantified relationship between the macroscopic visual parameters of a Diesel spray and its most influential factors. The factors considered are the ambient gas density, as an external condition relative to the injection system, and nozzle hole diameter and injection pressure as internal ones. The main purpose of this work is to validate and extend the different correlations available in the literature to the present state of the Diesel engine, i.e. high injection pressure, small nozzle holes, severe cavitating conditions, etc. Five mono-orifice, axi-symmetrical nozzles with different diameters have been studied in two different test rigs from which one can reproduce solely the real engine in-cylinder air density, and the other, both the density and the pressure. A parametric study was carried out and it enabled the spray tip penetration to be expressed as a function of nozzle hole diameter, injection pressure and environment gas density. The temporal synchronization of the penetration and injection rate data revealed a possible explanation for the discontinuity observed as well by other authors in the spray's penetration law. The experimental results obtained from both test rigs have shown good agreement with the theoretical analysis. There have been observed small but consistent differences between the two test rigs regarding the spray penetration and cone angle, and thus an analysis of the possible causes for these differences has also been included.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1383-1388
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• 2015

Proportional integral derivative (PID) control is one of the conventional control strategies. Industrial PID control has many options, tools, and parameters for dealing with the wide spectrum of difficulties and opportunities in manufacturing plants. It has a simple control structure that is easy to understand and relatively easy to tune. Injection mold is warming up to the idea of cycling the tool surface temperature during the molding cycle rather than keeping it constant. This “heating and cooling” process has rapidly gained popularity abroad. However, it has discovered that raising the mold wall temperature above the resin’s glass-transition or crystalline melting temperature during the filling stage is followed by rapid cooling and improved product performance in applications from automotive to packaging to optics. In previous studies, optimization methods were mainly selected on the basis of the subjective experience. Appropriate techniques are necessary to optimize the cooling channels for the injection mold. In this study, a digital signal processor (DSP)-based PID control system is applied to injection molding machines. The main aim of this study is to optimize the control of the proposed structure, including a digital PID control method with a DSP chip in the injection molding machine.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.251-256
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• 2003

The capability of pilot injection with small fuel quantity at all engine operating conditions is one of the main feature of the common rail system. The purpose of the pilot injection is to lower the engine noise and to reduce the NOx emissions. This study describes the pilot spray structure characteristics of the common-rail diesel injectors, solenoid-driven and piezo-driven type, with different electric driving characteristics So, three common-rail injectors with different electric current wave were used in this study. The pilot spray characteristics such as spray speed, spray tip penetration, and spray angle were obtained by spray images, which is measured by the back diffusion light illumination method with optical system for high-speed temporal photography. Also the CFD analysis was carried out for fuel behavior under high pressure in between needle and nozzle of solenoid-driven injector to know the condition of initial injection at experiment test. It was found that pilot injection of common-rail system was effected by rate of injection and temperature of injected fuel and electrical characteristic of the driven injector.

• Journal of Korean Medicine Rehabilitation
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• v.30 no.4
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• pp.133-142
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• 2020

Objectives Studies on Chinese herbal injections are increasing. But, its safety are still not well reported. We have reviewed the literature related to the safety of Chinese herbal injection, especially those related to anaphylaxis. Methods The PubMed database was used to select the literatures related to anaphylaxis in China and to study the quality control and safety of Chinese herbal injection. Results Chinese herbal injection is a major traditional medical treatment in China, but it is the cause of adverse drug reactions including anaphylaxis. In order to solve this problem, various proposals have been made to identify the pharmacological and chemical causes of major side effects and to use them safely clinically. In addition, various researches have been conducted from preclinical to postmarketing surveillance to secure the safety of Chinese herbal injection. Based on this, it was found that various efforts are needed to secure the safety of bee sting needles. Conclusion In order to secure the safety of chinese herbal injections, it is necessary to identify the main mechanism of action and the pharmacological components contributing to it, and to develop a standardized formulation based on this. In addition, institutional pharmacovigilance is required.

• Aerospace Engineering and Technology
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• v.5 no.2
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• pp.134-142
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• 2006

Sub-cooling of cryogenic propellant by helium injection is one of the most effective methods for suppressing bulk boiling and keeping sub-cooled liquid oxygen before rocket launch. In order to design the cooling system, understanding of the limitations of heat and mass transfer is required. In this paper, an analytical model for the helium injection system is presented. This model's main feature is the representation of bubbling system using finite-rate heat transfer and instantaneous mass transfer concept. With this simplified approach, the effect of helium injection to liquid oxygen system under several circumstances is examined. Experimental results along with simulations of single bubble rising in liquid oxygen and bubbling system are presented with various helium injection flow rates, and with change of oxygen chamber pressure.

• Korean Journal of Veterinary Service
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• v.41 no.4
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• pp.251-255
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• 2018

Bordetella bronchiseptica and Pasteurella multocida are two main pathogens responsible for atrophic rhinitis (AR), which causes considerable economic losses in swine industry worldwide. Commercial vaccine has been widely used to prevent the damage from AR in Korea. Adverse effects of vaccination at the injection site have been reported, which results in the numerous complaint from farms. However, data on about local reaction at the injection site remains limited. In this study, we compared the local adverse effects of three commercial vaccines following intramuscular injection. The results showed that no gross lesion was founded at the injection sites of all three vaccines. In histopathologic examination, a various level of lesions was identified. Especially, the local reaction of vaccine including saponin as an adjuvant showed the lowest level of histopathological lesions, when compared to those of oil-based and vitamin E-based vaccines. Therefore, this study would provide the information about the extent of local reaction at the injection site and help the farmer to select AR vaccine in order to avoid adverse reaction due to vaccination.