• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.2955-2960
• /
• 2007

To control the coating thickness of zinc in the process of continuous hot-dip galvanizing, it is known from early day that the gas wiping through an air knife system is the most effective because of the obtainable of uniformity of coating thickness, possibility of thin coating, working ability in high speed and simplicity of control. But, the gas wiping using in the galvanizing process brings about a problem of splashing from the strip edge for a certain high speed of coating. And, it is known that the problem of splashing is caused mainly by the existence of separation bubble at the neighbor of the strip surface. In theses connections, in the present study, we proposed two kinds of air knife systems having the same expansion rate of nozzle, and the jet structures and coating thicknesses from a conventional and new proposed nozzles are compared. In numerical analysis, the governing equations consisted of two-dimensional time dependent Navier-Stokes equations, standard ${\kappa}-{\varepsilon}$ turbulence model to solve turbulence stress and so on are employed. As a result, it is found that it had better to use the constant rate nozzle from the point view of the energy saving to obtain the same coating thickness. Also, to reduce the size of separation bubble and to enhance the cutting ability at the strip, it is recommendable to use an air knife having the constant expansion rate nozzle.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.4
• /
• pp.194-202
• /
• 2005

The objective of this paper is to develop a multi-functional hotwire cutting system (MHC) using EPS-foam block or plate as the working material. Because the MHC apparatus employs a four-axis synchronized hotwire cutter with the structure of two XY movable heads and a turntable, it allows the easy fabrication of various 3D shapes, such as (1) an axisymmetric shape or a sweeping cross-sectioned pillar shape using the hot-strip in the form of sweeping surface and EPS foam block on the turntable, (2) a polyhedral complex shape using the hotwire and EPS foam block on the turntable, and (3) a ruled surface approximated freeform shape using the hotwire and EPS foam plate. In order to examine the applicability of the developed MHC apparatus, an axisymmetric shape, a polyhedral shape and a large-sized freeform shape were fabricated on the apparatus.

• Journal of Industrial Technology
• /
• v.26 no.B
• /
• pp.35-41
• /
• 2006

Recently, as ultrasonic medical devices are gradually developed, many of those requires smaller and more precision coaxial cables in probe. So, the use of micro coaxial cable becomes an efficient solution for ultrasonic machine. However, there are many difficulties in stripping micro coaxial cable by traditional mechanical process. In this paper, we use the Nd-YAG laser for the efficient stripping of conduct wire of cable. We propose a new method to strip the shield wire of micro coaxial cable. Through some experiments, we found that there is a new possibility in the proposed method. Also, in order to enhance the performance, we propose a preprocess of the cable before stripping.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.58-59
• /
• 2011

Microstrip line on dielectric substrate depending on the type of its configuration can be applied to be antenna, communication filters, and resonators. When driving frequency is considered more than X-band, unnecessary signal leakage should be occurred because of flowing through the planar circuit at banding position. So leakage signal will affect other planar circuit, and then EMC problem has to be introduced. In this paper, the affection of banding planar circuit on dielectric substrate was investigated.

• Journal of Korean Society of Forest Science
• /
• v.88 no.4
• /
• pp.438-445
• /
• 1999

The concentrations of some ions ($NO{_3}^-$, $Ca^{2+}$, $Mg^{2+}$, $NH{_4}^+$) in soil solution collected by zero tension lysimeter in mature Pinus rigida plantations in Goksung, Jeonranam-do were measured at two soil depths (10cm and 30cm) following various levels of cutting intensity treatment (uncut, $6m{\times}50m$, $10m{\times}50m$, $20m{\times}50m$ strip crearcutting) three times (July 6. July 30, and August 4) between June 20 and August 4 1998. The ion concentrations in the soil solution were significantly different among sampling times, while the concentrations were not different among cutting levels or sampling depths. The ion concentrations in the soil solution decreased in the order of $NO{_3}^-$ > $Ca^{2+}$ > $Mg^{2+}$ > $NH{_4}^+$ and the mean concentration was 3.60mg/L for $NO{_3}^-$, 1.7mg/L for $Ca^{2+}$, 0.5mg/L for $Mg^{2+}$, and 0.04mg/L for $NH{_4}^+$ respectively. These ion concentrations except for $NH{_4}^+$ ion were negatively correlated with the volume of collected soil solutions (r=-0.31~-0.41). The results suggest that the change of nutrient concentrations in the soil solution collected from the P. rigida plantations was related to the temporal input patterns of precipitation rather than the cutting intensity.

• Food Science and Preservation
• /
• v.10 no.1
• /
• pp.6-10
• /
• 2003

The objective of this study was to investigate the effect of browning inhibitor and vacuum packaging on minimally processed sweet pumpkin. The browning inhibitor were lo/e of ascorbic acid, citric acid, NaCl, MgCl$_2$and their combination. For the minimal processing, sweet pumpkin was sliced and strip-cut followed by dipping in the solution of browning inhibitor. Effective browning inhibitors fer slice sweet pumpkin were ascorbic acid, NaCl and MgC1$_2$, and those fer thin strip were combination and ascorbic acid. The hardness of minimally processed sweet-pumpkin repeated increasing and decreasing and decreased in the final of storage. However the change pattern of hardness was different according to cutting method. Magnesium chloride treatment was generally high grade on sensory characteristics. Sweet pumpkin treated with citric acid was distinguished on carbon dioxide generation and oxygen exhaustion.

• Journal of computational fluids engineering
• /
• v.14 no.1
• /
• pp.1-8
• /
• 2009

To control the coating thickness of zinc in the process of continuous hot-dip galvanizing, it is known from early days that the gas wiping through an air knife system is the most effective because of the obtainable of uniformity of coating thickness, possibility of thin coating, working ability in high speed and simplicity of control. But, the gas wiping using in the galvanizing process brings about a problem of splashing from the strip edge for a certain high speed of coating. Also, it is known that the problem of splashing directly depends upon the galvanizing speed and nozzle stagnation pressure. In theses connections, in the present study, we proposed two kinds of air knife systems having the same expansion rate of nozzle, and the jet structures and coating thicknesses from a conventional and new proposed nozzles are compared. In numerical analysis, the governing equations consisted of two-dimensional time dependent Navier-Stokes equations, standard k-e turbulence model to solve turbulence stress and so on are employed. As a result, it is found that it had better to use the constant rate nozzle from the point view of the energy saving to obtain the same coating thickness. Also, to enhance the cutting ability at the strip, it is advisable to use an air knife with the constant expansion rate nozzle.

• Journal of Korean Society of Forest Science
• /
• v.97 no.5
• /
• pp.540-546
• /
• 2008

Enrichment planting has been used as one of the promising restoration techniques to accelerate the natural restoration process of secondary forests or logged-over forests in Myanmar, The objectives of this study were to examine the growth performances of two commercial species such as Teak (Tectona grandis Linn f.) and Padauk (Pterocarpus macrocarpus Kurz) in response to different canopy opening treatments and to examine the suitability of these species in enrichment planting activities for the restoration of degraded tropical forests in Myanmar. In this study, split plot design was applied, and three levels of canopy openings were experimented. The survival rate and height growth of two species were measured four times with 6 month interval. The root collar diameter (RCD) was also measured in the last assessment. Although the survival rate of seedlings was not significantly different among the three treatments (p>0.05) as well as between two species (p>0.05) for all consecutive measurements, height (p<0.05) and RCD were significantly different (p<0.001) among the treatments, T. grandis seedlings thrived best under complete canopy opening (i.e., 5 m width canopy opening with strip-clear cutting) while P. macrocarpus seedlings under partial canopy opening (without felling of marketable tree species). Because this study is concerned with only for young stage of seedlings, continuous assessment and follow-up tending activities are needed to verify the species suitability and optimum width of canopy opening for enrichment planting activities in restoration of degraded forests of Myanmar.

• Journal of the Korean Society of Costume
• /
• v.19
• /
• pp.105-125
• /
• 1992

The research, aiming an automatic pattern design of Korean Costume by utilizing CAD system, tried Grading, Seaming and Marking with a theme of girl's color-strip blouse & skirt. The content & conclusion of the research can be outlined as follows; 1) As we reviewed the current situation of Korean costume which becomes more likely celebrational or festival costume, while the demand of it is getting increase, it's being dealt mostly as ready-made dresses with different qualities & designs. Especially childrens ready-made ones were highly demanded to be picked up as the theme. 2) For the original drawing of children's color-strip blouse & skirt, Kyung-Ja Park's drawing method was used here, and for the substitute of particular body parts absolute size, Joo-Won Lee's standard size chart from a size-study by ages. 3) To work with CAD system we had input master pattern, drawn for age 5 as basic size, then graded six step-sizes for 1-11 years old. For add-subtract of particular body parts size, we graded through computing the standard variation among items to get the pattern developed into ready-made standard size, we can make precise plotting by grading wanted size very rapidly if we correct the rule of changed items different from standard size to make utilization possible enough with easy order method of ready-made Korean Dress. 4) We produced Marker after attaching a margin to seam accordingly by parts for each pattern using P/D/S to mark, In mass gament-cutting, the loss of time and material can minimized. In this research the apparel CAD system which has been utilized and only be western fashion industry was introduced for the design of ready-made Korean costume and utilized it in Grading, Marking which are critical steps to improve productivity and have reported the result in the research. Thus we expect that less cost, improved productivity and better quality with minimized loss of material from marking as well as from prompt and precise size-drawing. Furthermore the utilization of CAD system is considered as an effective one in terms of the research & the development to remove effective one in terms of the research & the development to remove irrational elements in the design and production process of Korean costume as well as in terms of the study of Korean Costume development through creative works of Korean Costume.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.10a
• /
• pp.239-242
• /
• 2005

In the roll forming, a flat strip is progressively deformed by feeding it through a series of rotating rolls. There are various layouts for the tube toll-forming stages. The process sequences are as follows: leveling, roll-forming, welding, bead removing, seam annealing, cooling, sizing and cutting. Electric resistance welded(ERW) tubes have been widely used for the machinery parts, especially for hydroformed automotive parts. However conventional ERW tubes do not have a high formability because of hardening of welded portion by rapid cooling. Moreover the decrease in thickness of the welded portion during the grinding of the inner and outer bead may reduce the formability of the tube. In case of applying the tubular parts without grinding the bead, the flow of the fluid can be prevented due to the turbulent flow induced by the inner bead. In attempt to determine the optimal bead grinding amount in the roll forming process, in the present paper, the effects of the removal depth and width of the inner beads on the hydroformability are analyzed by the finite element simulation.