• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.10
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• pp.414-419
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• 2016

Air flow measurement is a fundamental and important task for testing, adjusting, and balancing of HVAC system. However, it is difficult to carry out in the field due to the large size and weight of the flow meter. In this study, for the purpose of developing a small and portable flow meter, we proposed a different method of static pressure measurement and verified it experimentally. In the proposed method, static pressure difference was measured by inserting a tube inside the chamber before and after the nozzles. The results were compared with measurements according to the ANSI/ASHRAE standard. The results were in good agreement, indicating that the inserted tube method could be used for static pressure measurement of a portable flow meter. The proposed method eliminates the pressure tubes that are attached outside, which results in smaller size and easy handling.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.130-131
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• 2011

In the present work, a synchronization test system for variable nozzle is described. Variable nozzles are used to enhance the effectiveness of aircraft engines at various altitudes. The synchronization test system was developed to verify the dynamic characteristics and synchronization of variable nozzle mechanism including flaps. The system with a variable nozzle was analyzed, before its fabrication, by a multi-body dynamics analysis software RecurDyn. The newly developed test system is being used to show the synchronization capability of a variable nozzle system.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.566-571
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• 2005

Process of screw-pumping system (SPS) was optimized for mass production of encapsulated bifidus. SPS entrapment device was composed of feeding component, with optimized nozzle size and length of 18G (0.91 cm) and 4 mm, respectively, screw pump, and 37-multi-nozzle. Screw component had five wing turns [radius (r)=26 to 15 mm] from top to bottom of axis at 78-degree angle from middle of the screw, and two wings were positioned at screw edge to push materials toward nozzle. For nozzle component, 37 nozzles were attached to 20-mm round plate. Air compressor was attached to SPS to increase productivity of encapsulated bifidus. This system could be operated with highly viscous (more than 300 cp) materials, and productivity was higher than $1128\;{\pm}\;30\;beads/min$. Viability of encapsulated bifidus was $5.45\;{\times}\;10^8\;cfu$/bead, which is superior to that of encapsulated bifidus produced by other methods ($2.51{\times}10^8\;cfu$/bead). Average diameter of produced beads was $2.048\;{\pm}\;0.003\;mm$. Survival rate of SPS-produced encapsulated bifidus was 90% for Simulator of the Human Intestinal Microbial Ecosystem test and 88% in fermented milk (for 14 days). These results show SPS is effective for use in development of economical system for mass production of viable encapsulated bifidus.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.229-234
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• 2021

This study investigated spray patterns and coverage generated by three types of commercial nozzles for spraying pesticides with Unmanned Aerial Vehicles (UAVs) using a multi-copter. Flufenoxuron+metaflumizone SC and bifenthrin EC were sprayed. The falling particles of the spraying agent were measured using WSP (Water and oil Sensitive Paper) and the coverage was determined. The results showed that the uniformity of falling particles was different according to the difference in wind strength, and there was no difference for different formulations. The injection amount for each nozzle was found to be different from the official information provided by the manufacturers. These results could be used to establish guidelines for the control of UAVs and pesticide registration testing.

• Journal of The Korean Institute of Defense Technology
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• v.5 no.4
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• pp.9-15
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• 2023

In this study, electric field analysis was conducted for each process as a preliminary step in the design of the electrospinning device to apply the electrospinning PVDF nanofibers to increase the filtering effect of insect screens. In the electrospinning analysis using a single nozzle, it was confirmed that there was a decrease in the electrostatic field strength as the tip's size decreased, an increase in the voltage, and no effect depending on the TCD distance. In addition, it was confirmed that the closer the distance between tips, the more electric field interference occurs, and this was found to have a more significant effect on the tip located in the center with tips on both sides. Therefore, based on these analytical results, it is believed that an increase in production speed can be expected by establishing an efficient process line by confirming the radiating area of the collector and designing the spacing between multi-nozzles through actual experiments.

• Journal of Powder Materials
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• v.24 no.1
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• pp.46-52
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• 2017

Fecralloy coating layer with large surface area is suitable for use as a filter media for efficient removal of hot gaseous pollutants exhausted from combustion processes. For uniform preparation of a Fecralloy coating layer with large surface area and strong adhesion to substrate, electrospray coating and thermal treatment processes are experimentally optimized in this study. A nano-colloidal solution with 0.05 wt% Fecralloy nanoparticles is successfully prepared. Optimized electrospraying conditions are experimentally discovered to prepare a uniform coating layer of Fecralloy nano-colloidal solution on a substrate. Drying the electrospray coated Fecralloy nano-colloidal solution layer at $120^{\circ}C$ and subsequent heating at $600^{\circ}C$ are the best post-treatment for enhancing the adhesion force and surface roughness of the Fecralloy coating layer on a substrate. An electrospray coating system, consisting of several multi-groove nozzles, is also experimentally confirmed as a reasonable device for uniform coating of Fecralloy nano-colloid on a large area substrate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.221-228
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• 2017

We proposed a novel method to remove PM2.5 dusts without HEPA filters aiming at applications in kitchens or enclosed work spaces generating PM2.5 at high concentrations. Many workers are exposed to PM2.5 owing to lack of air purification because the high replacement costs of HEPA filters make their application impractical. A key idea is to use the condensational growth of nanoparticles. Once particles grow to the size of a few micrometers, it is much easier to remove them because of their increased inertia. We developed and tested a prototype consisting of an air saturator (equipped with water spray nozzles), a condenser in which humid air was cooled down to make the particles grow, and a multi-impactor assembly for collecting the grown particles.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.157-163
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• 2018

This study is aimed at controlling the fiber orientation and improve the fiber distribution in fiber-reinforced cement composites using blades that can be placed inside the existing nozzles. To optimize the blade parameters, multi-physics finite element analysis was performed that could account for the flow of the cementitious matrix material, the movement of the entrained fibers, and the interactions with the nozzle. As a result, this study defined the blade distance, length, and position as a function of the fiber length to be used in the field. The blades with a distance from 1.2 to 2.4 times the fiber length and length from 4 to 8 times the fiber length, as well as located at below 14 times the fzfiber length from the nozzle exit maintained the fiber orientation angle less than $5^{\circ}$. In addition, the blade-type nozzle proposed in the study can be attachable and detachable to the conventional casting equipment, and thus it can provide the usability and convenience in practical applications.