• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.4
• /
• pp.324-329
• /
• 2020

The emergency evacuation support system provides a safe means of evacuation by preventing the inflow of smoke through the formation of a smoke shield curtain in fire situations and pressurizing fresh air to the inside of the smoke shield curtain. In this study, numerical analysis was performed to examine the effects of the hole size on the flow inside the smoke curtain. As the air supply size decreased, the flow rate through the air supply was formed relatively uniformly from the inlet to the outlet length of the emergency support system. In addition, the size of the air supply hole was more than 20 mm, the flow rate was very low near the outlet, so the air supply hole size should be smaller than 20 mm. In addition, the minor loss of the air supply hole was calculated to be K = 1.5 from the numerical results. Therefore, the proper design of an emergency evacuation support system is possible using the flow characteristics according to the size and minor loss of the air supply hole.

• Food Science and Preservation
• /
• v.10 no.4
• /
• pp.466-469
• /
• 2003

To develope corrugated paperboard box for cold chain system, it was investigated to compression strength and size of air hole. The size of air holes of the side tested box were designed as six groups, 4, 7, 10% and two kind of air hole, 2, 3 hole per the side. Compression strength of box(440${\times}$330${\times}$170 mm(length${\times}$width${\times}$height))was tested by compression tester UM-20Y, DaeSin Co., Korea, speed is 12.5 mm/min), it was stored 4 week at room temperature, RH 70${\times}$5%. Compression strength was high the mort narrow, the longer of air hole. Compression strength of box of the side, 4% was 10% higher among 4, 7, 10%, but differentiate of compression strength owing to the number of air hole was below 10%. for improving the compression strength of box, paper board box for cold chain system was made of the narrow of width and of the long length of air hole.

• Journal of the Semiconductor & Display Technology
• /
• v.6 no.1 s.18
• /
• pp.59-64
• /
• 2007

Non-contact transportation of a large-sized glass plate using air cushion for the vertical sputtering system of liquid crystal display (LCD) panel was considered. The objective of the study was to design an air pad unit which was composed of multiple injection and exhaust holes and mass flow supplying pipe. The gas was injected through multiple small holes to maintain the force for levitating glass plate. After hitting the plate, the air was vented through exhaust holes. Complex flow field and resulting pressure distribution on the glass surface were numerically studied to design the air injection pad. The exhaust hole size was varied to obtain evenly distributed pressure distribution at fixed diameter of the injection hole. Considering the force for levitating glass plate, the diameter of the exhaust hole of 30 to 40 times of the gas injection hole was recommended.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1555-1558
• /
• 2005

In this study, we measured cylindricity and Runout of the air bearing spindle, and tested PCB(printed circuit boards) drilling with 0.4mm micro drill at 90,000rpm and 110,000rpm in order to obtain drilling hole error. Results are as follows; The air bearing spindle's Runout was not so high within $10\mu{m}$ from 20,000rpm to 80,000rpm but it grew after 80,000rpm. Drilling hole size error was 9% at 80,000rpm and 12% at 110,000rpm because of spindle's Run out. Drilled hole shape falsified more 110,000rpm than 90,000rpm.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.11 no.2
• /
• pp.144-151
• /
• 2008

An experimental study has been conducted to investigate the effects of circular damage hole on the characteristics of airfoil performance. The damage on a wing created from a hit by anti-air artillery was modeled as a circular hole. Force balance measurements and static pressure measurements on the wing surface were carried out for the cases of having damage holes of 10% chord size at quarter chord and/or half chord positions. All experiments were conducted at Reynolds number of $2.85\times10^5$ based on the chord length. The surface pressure data show big pressure alterations near the circular damage holes. This abnormal surface pressure distribution produces shear stress that could lead to the acceleration of the structural degradation of the wing around the circular damage hole. However, in spite of the existence of circular damage holes, the measured force data indicated the only a slight decrease in lift accompanied by increase in drag compared to the results of undamaged one. The influence of damage hole on the aerodynamic performance was increased as the location of damage moved to the leading edge. The effect on the control force was insignificant when the damaged size was not large.

• Journal of the Korean Society of Visualization
• /
• v.9 no.3
• /
• pp.38-43
• /
• 2011

When draining takes place through an axially located drain port in a cylindrical tank without any prevent, a vortex with an air core occurs. In this study, semi spherical concave and convex meshes with different size inner hole are used to find the air core can suppress. The study is carried out with different values of inner hole of mesh and different install direction of semi spherical mesh using PIV and measured velocity distribution. By providing a mesh, the air core can be prevented, even if the ratio of inner hole of mesh and diameter of cylinder is around 0.66. The experimental results show that a convex mesh type is more effective to suppress the air core generation than a concave mesh type.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.5
• /
• pp.112-120
• /
• 2005

The injector, which is used in a 4-valve gasoline engine, is required to be maintained the dual stream because of the design of dual intake port. In addition, the spray characteristics of fuel injector have strong influence on engine performance, exhaust emission, fuel consumption, and especially the cold start condition for the port injection. So, commercial gasoline injectors off different type were inspected. Those are 2 hole,4 hole, air shroud 4 hole, and air shroud 4 hole injector with separator. The spray behavior of dual stream was researched by the visualization system and PDPA system was employed to measure the droplet size. Atomization is one of the most important characteristic, so droplet size distributions and SMD are investigated. And the spray characteristics of each injector are also analyzed such as the spray tip penetration, spray angle, and separation angle.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
• /
• 2006.10a
• /
• pp.138-144
• /
• 2006

Non-contact transportation of a large-sized glass plate using air cushion for the sputtering system of liquid crystal display panel was considered. The gas is injected through multiple small holes to maintain the force for levitating glass plate. Complex flow field and resulting pressure distribution on the glass surface was numerically studied to design the air injection pad. The exhaust hole size was varied to obtain evenly distributed pressure distribution at fixed diameter of the injection hole. Considering the force for levitating glass plate, the diameter of the exhaust hole of 30 to 40 times of the gas injection hole was recommended.

• Journal of Biosystems Engineering
• /
• v.20 no.4
• /
• pp.351-359
• /
• 1995

In pressure cooling system, produce were packed in vented box and cooled rapidly by producing a difference in air pressure on opposite faces of stacks of vented box. So, energy requirements and performance of pressure cooling system depended upon the air flow rate and the static pressure drop through packed produce in vented box. The static pressure drop across packed produce in vented box normally depended upon air flow rate, vent area of box and conditions of produce bed (depth, porosity, stacking patterns, size and shape of products) in box. The objectives of this study were to investigate the effect of vent area and air flow rate on airflow resistance of empty box and packed produce in vented box, and to investigate the relationship between the air flow resistance of packed products in vented box and sum of air flow resistance of empty box only and products in bulk only. Mandarins and tomatoes were used in the experiment. The airflow rate were in the range of 0.02~1.0$m^3$/s.$m^2$, the opening ratio of vent hole were in the range of 2.5~20% of the side area. The results were summerized as follows. 1. The pressure drops across vented box increased in proportion to superficial air velocity and decreased in proportion to opening ratio of vent hole. A regression equation to calculate airflow resistance of vented box was derived as a function of superficial air velocity and opening ratio of vent hole. 2. The pressure drops across packed produce in vented box increased in proportion to superficial air velocity and decreased in proportion to opening ratio of vent hole. 3. Because of the air velocity increase in the vicinity of vent hole in box, the airflow resistances of packed products in vented box were always higher than sum of air flow resistance of empty box only and products in bulk only. 4. Based on the airflow resistance of empty box and products in bulk, a regression equation to calculate airflow resistance of packed products in vented box was derived.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2002.11a
• /
• pp.321-326
• /
• 2002

To design mechanical ventilation for bathroom of apartment houses where air supply and exhaust are taken Into consideration, mock-ups of ventilation systems, widely used in bathroom of apartment houses with an area of 100$m^2$, were made and installed in a laboratory, These ventilation mock-ups were available for control of air supply and exhaust, and the size of supply openings were 40cm$\times$1cm, 40cm$\times$3cm, 40cm$\times$5cm. They were installed at five positions, spaced 40cm at a height of 25cm from the floor. and the position of exhaust fans were four corners and center Exhaust fan established each one on corner of the ceiling and one in center. As result that measure ventilation effect by each condition, size of hole that supply air is big, and ventilation effect took effect to be good establishment location is low, Also, distance of exhaust fan is far with hole that supply air, ventilation effect took effect by superior thing.