• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.773-776
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• 2005

An Experiment was carried out to study deburring in frilling hole on the Inclined exit surface. Two different deburring tools, exit surface angles, materials and cutting conditions were selected to check their performance using CNC machining center. In deburring operation, there are not only flat exit surfaces but also inclined exit surfaces which is described as inclination angle. Inclination of exit surface causes a quite different burr formation when comparing with flat surface. Deburring characteristics are analyzed according to the deburring tools and cutting conditions. Several strategies for a effective deburring on inclined exit surface were proposed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.47-50
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• 2003

We carried out rock pneumatic fracturing test which to increase groundwater yield by injection of highly pressured air in artificially under the surface every four borehole. The result of test performing shows that effect of increasing groundwater was not found in three testhole around igneous and metamorphic formation area, but we can realized that about 15 percent increased wateryield appeared in number P-5 test hole at sedimmentary rock formation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.11a
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• pp.260-265
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• 2004

LTCC(Low temperature co-fired ceramic) is being recognized as a significant packaging material of electrical devices for the advantages such as relatively low temperature being needed for process, low conductor resistance and high printing resolution. In the process of LTCC electrical devices, the punched via-hole quality is one of the most important factors on the performance of the device. However, its mechanism is very complicated and optimization of the process seems difficult. In this paper, to clarify the process, via-hole punching experiments were carried out and the punched holes were examined in terms of their burr formation. The effects of thickness of PET sheet and ceramic sheet and punch-to-die clearance on via-hole quality were also discussed. Optimum process conditions are proposed and a factor k is introduced to express effect of the process variables.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.151-158
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• 2005

A characteristic of discharge for a foam spray nozzle with various parameters was investigated. The discharge patterns from a fire foam spray nozzle are important to evenly spray over a maximum possible floor area. Two parameters of a foam spray nozzle were chosen, and compared with those from the standard one. Also, in order to evaluate the performance of discharged foam agents used to protect structures from heat and fire damages, the thermal characteristics of fire-protection foams were experimentally investigated. A simple repeatable test for fire-protection foams subjected to fire radiation was developed. This test involves foam generation equipment, a fire source for heat generation, and data acquisition techniques. Results show that the bubble size of foam is increased by large inside diameter of orifice or closed air hole, but phenomenon of discharge angle and expansion ratio is opposite. For the case of the open air hole, liquid film of a circular cone discharges with formation, growth, split and fine grain. In case of the closed air hole, a pillar of foam solution discharges with that. Though the temperature gradient in the foam increases with increased foam expansion ratio. it is not change with increased intensity of heat flux.

• Macromolecular Research
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• v.17 no.11
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• pp.894-900
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• 2009

This study examined the charge carrier photogeneration and hole transport properties of blends of poly (9-vinylcarbazole) (PVK), $\pi$-conjugated polymer, with different weight proportions (0~29.4 wt%) of (PEA)$VOPO_4{\cdot}H_2O$ (PEA: phenethylammonium cation), a novel organic-inorganic hybrid material, using IR, UV-Vis, and energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), steady state photocurrent (SSPC) measurement, and atomic force microscopy (AFM). The SSPC measurements showed that the photocurrent of PVK was reduced by approximately three orders of magnitude by the incorporation of a small amount (~12.5 wt%) of (PEA) $VOPO_4{\cdot}H_2O$, suggesting that hole transport occurred through the PVK carbazole groups, whereas a reverse trend was observed at high proportions (>12.5 wt%) of (PEA)$VOPO_4{\cdot}H_2O$, suggesting that transport occurred via (PEA)$VOPO_4{\cdot}H_2O$ molecules. The transition to a trap-controlled hopping mechanism was explained by the difference in ionization potential and electron affinity of the two compounds as well as the formation of charge percolation threshold pathways.

• ALGAE
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• v.30 no.1
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• pp.59-66
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• 2015

The growth and hole formation of Ulva australis were examined at seven coastal areas of Korea between July and August, 2013. Animal species and weight growing on the Ulva fronds were estimated at Haseom, Pohang, and Woedo. The effects of wave exposure on the morphological features and residential animals of Ulva fronds were investigated at wave-exposed and sheltered sites of Seongsan on October 19, 2013. U. australis had different frond areas ($82-665cm^2$), hole areas ($2.5-6.3cm^2$), and hole numbers (9.8-41.3 holes) at the seven sites. Within $0.1m^2$ of Ulva frond, hole areas ranged from 0.37 to $5.94cm^2$, and between 4.9 and 36.2 holes were observed. Fourteen residential animal species were observed at the three evaluated sites, 75.0 (Haseom) to 408.7 individuals $100g^{-1}$ Ulva (Pohang) per site. The dominant residential species at each site differed with Amphithoe sp. at Haseom, Monodonta spp. at Pohang, and Pagurus sp. at Woedo. The growth (frond area, wet weight) and hole number of Ulva fronds, and the number of residential animals were significantly greater in samples collected from the sheltered shore than the wave-exposed shore of Seongsan. The present results showed U. australis grew well at sheltered shores and had more holes on the fronds due to abundance of residential animals. The dominant residential animals (crabs, gammaridea, and snails) were similar in the Ulva populations of sheltered and wave-exposed shores, but greater species diversity was observed at the exposed shore (18 species ver. 11 species). In conclusion, U. australis is a keystone species providing habitat to various invertebrates and frond holes are positively correlated to the number of residential animals.

• Journal of Biosystems Engineering
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• v.42 no.2
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• pp.104-111
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• 2017

Purpose: We have studied the necessary qualities of seedlings of some leafy vegetables for a riding-type two-row automatic transplanter. When seedlings are planted using a transplanter, long roots may be rounded in the bottom of the tray, and this can interfere with the separation of the seedlings. Uprightness related to leaf spread angle is an important quality for seedlings in mechanical planting. Methods: To select cultivars suitable for the transplanter, we compared varieties of Kimchi cabbage (Chukwang, Daetong, Whipalam and Namdo), head lettuce (Abi and Sensation), cabbage (YR Onnuri, YR Hogel, Harutama, and Ogane), and broccoli (Nicegreen and Earlyyou). To compare the effect of bed soil on root formation and growth, we used five types of soil: Chologi, Burger, Wonjomix, Bio, and Baroker with 2.6-3 L per tray. Growth increment and the degree of root formation were measured according to the RDA guidelines 25 days after sowing for Kimchi cabbage and head lettuce and 44 days after sowing for cabbage and broccoli. Conclusions: According to the plug tray, the optimum seedling age in both 128- and 200-hole trays was 28 days for Kimchi cabbage and 44 days for cabbage and broccoli. Head lettuce took 35 days in 128-hole trays and 31 days in 200-hole trays. Burger soil was most effective for root formation and growth of the four kinds of leafy vegetables; it appeared that smaller soil volume led to faster root formation.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.747-754
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• 2023

Energy-efficient routing protocol is an important task in a wireless sensor network that is used for monitoring and control by wirelessly collecting information obtained from sensor nodes deployed in various environments. Various routing techniques have been studied for this, but it is also necessary to consider WSN environments with specific situations and conditions. In particular, due to topographical characteristics or specific obstacles, a hole where sensor nodes are not deployed may exist in most WSN environments, which may result in inefficient routing or routing failures. In this case, the geographical routing-based hall bypass routing method using GPS functions will form the most efficient path, but sensors with GPS functions have the disadvantage of being expensive and consuming energy. Therefore, we would like to find the boundary node of the hole in a WSN environment with holes through minimal sensor function and propose hole bypass routing through boundary line formation.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.328-333
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• 2023

This study experimentally verified the etch rate of the SiO₂ sacrificial layer etching process with a single etch hole using vapor-phase hydrogen fluoride (VHF) etching. To fabricate small-sized polysilicon etch holes, both circular and triangular pattern masks were employed. Etch holes were fabricated in the polysilicon thin film on the SiO₂ sacrificial layer, and VHF etching was performed to release the polysilicon thin film. The lateral etch rate was measured for varying etch hole sizes and sacrificial layer thicknesses. Based on the measured results, we obtained an approximate equation for the etch rate as a function of the etch hole size and sacrificial layer thickness. The etch rates obtained in this study can be utilized to minimize structural damage caused by incomplete or excessive etching in sacrificial layer processes. In addition, the results of this study provide insights for optimizing sacrificial layer etching and properly designing the size and spacing of the etch holes. In the future, further research will be conducted to explore the formation of structures using chemical vapor deposition (CVD) processes to simultaneously seal etch hole and prevent adhesion owing to polysilicon film vibration.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.209-211
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• 2006