• Transactions of Materials Processing
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• v.15 no.1 s.82
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• pp.9-14
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• 2006

In the present research, the simultaneous punching of ultra small size hole of $2\~10\;{\mu}m$ in diameter on flat rolled thin metal foils was conducted with elastic polymer punch. Workpiece used in the present investigation were the rolled pure copper of $3{\mu}m$ in thickness and CP titanium of 1.5fm in thickness. The metal foils were punched with the dies and arrays of circular and rectangular holes were made. The process set-up is similar to that of the flexible rubber pad farming or Guerin process. Arrays of holes were punched successfully in one step forming. The punched holes were examined in terms of their dimensions. The effects of the wafer die hole dimension and heat treatment of the workpiece on ultra small size hole formation of the thin foil were discussed. The process condition such as proper die shape, pressure, pressure rate and diameter-thickness ratio (d/t) were also discussed. The results in this paper show that the present method can be successfully applied to the fabrication of ultra small size hole away in a one step operation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.193-197
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• 2005

This paper presents a method by which multiple holes of ultra small size can be punched simultaneously. Silicon wafers were used to fabricate punching die. Workpiece used in the present investigation were the rolled pure copper of $3{\mu}m$ in thickness and CP titanium of $1.5{\mu}m$ in thickness. The metal foils were punched with the dies and arrays of circular and rectangular holes were made. The diameter of holes ranges from $2-10{\mu}m$. The process set-up is similar to that of the flexible rubber pad forming or Guerin process. Arrays of holes were punched successfully in one step forming. The punched holes were examined in terms of their dimensions, surface qualities, and potential defect. The effects of the die hole dimension on ultra small size hole formation of the thin foil were discussed. The optimum process condition such as proper die shape and diameter-thickness ratio (d/t) were also discussed. The results in this paper show that the present method can be successfully applied to the fabrication of ultra small size hole array in a one step operation.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.131-135
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• 2002

In this project, we have developed various techniques for subminiaturization, surface implementation, high frequency design, small-sizes SMD, performance test and applications of ultra small chip antenna, which is a core component for the personal communication systems. We also obtained base techniques for the next-generation ultra small chip antenna design and fabrication techniques for an internationally competitive subminiature ultra small chip antenna. Center frequency is 2442.5MHz(Type), return loss is -10dB max, VSWR is 2max, xy max gain is -2dB min, size is 0.05ccmax.

• Journal of the Korean Society of Food Culture
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• v.22 no.5
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• pp.645-651
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• 2007

Male weanling Sprague Dawley rats were used to evaluate the effect of dietary rice starch with different particle size on growth performance, intestinal function and proliferation. There were two dietary treatment: rice starch (RS), ultra finely pulverized rice starch with less than $15{\mu}m$ size (PRS). They were eight rats per treatment. In vitro digestibility, body weight change and organs weight were evaluated. Serum GPT, GOT and blood urea nitrogen were analyzed. Transit time, short chain fatty acid contents of cecum, and cell proliferation of duodenum and jejunum were measured. In vitro digestibility of PRS was higher than that of RS. Rats fed ultra finely pulverized rice starch for 3 weeks grew faster than rats fed rice starch. PRS group has higher weights of liver, kidney, spleen and epididymal fat pad, perhaps as a result of increased digestibility. GPT and GOT were not different between two groups. Blood urea nitrogen was higher in RS-fed rats than that of PRS-fed rats. Feeding ultra finely pulverized rice starch resulted in a proliferation of duodenum significantly. These results suggest that ultra finely pulverized rice starch increases the growth performance in weanling animals with reduced number of cells in the cell cycle of small intestine.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.3
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• pp.340-347
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• 2004

Ultra-small size, high-performance, solenoid-type RF chip inductors utilizing low-loss A1$_2$O$_3$ core materials were investigated. The dimensions of the RF chip inductors fabricated were 1.0mm${\times}$0.5mm${\times}$0.5mm and copper coils were used. The materials (96％ A1$_2$O$_3$) and shape (I-type) of the core, the diameters (40${\mu}{\textrm}{m}$) and position (middle) of the coil, and the lengths (0.35mm) of solenoid were determined by a high-frequency structure simulator (HFSS) to maximize the performance of the inductors. The high-frequency characteristics of the inductance (L) and quality-factor (Q) of the developed inductors were measured using a RF impedance/material analyzer (E4991A with E16197A test fixture). The developed inductors exhibit an inductance of 11 to 11.3nH and a qualify factor of 22.3 to 65.7 over the frequency ranges of 250 MHz to 1.7 GHz, and show results comparable to those measured for the inductors prepared by Coilcraft$^{TM}$. The simulated data described the high-frequency data of the L and Q of the fabricated inductors well.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1237-1241
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• 2003

In this paper, we report a novel RF-MEMS packaging technology with lightweight, small size, and short electric path length. To achieve this goal, we used the ultra thin silicon substrate as a packaging substrate. The via holes lot vortical feed-through were fabricated on the thin silicon wafer by wet chemical processing. Then, via holes were filled and micro-bumps were fabricated by electroplating. The packaged RF device has a reflection loss under 22 〔㏈〕 and a insertion loss of -0.04∼-0.08 〔㏈〕. These measurements show that we could package the RF device without loss and interference by using the vertical feed-through. Specially, with the ultra thin silicon wafer we can realize of a device package that has low-cost, lightweight and small size. Also, we can extend a 3-D packaging structure by stacking assembled thin packages.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.932-937
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• 2000

The length extensional vibration mode of a piezoelectric ceramic substrate is used in fabricating the ultra-small size resonators and filters. In general, the three side ratios of the rectangular substrate affect the resonant characteristics of the resonator using its length extensional vibration. In this paper, their relationships are studied. We know that changing the ratio of its length to its width makes possible to change the resonant frequency of the width vibration without degrading the length extensional vibration. And frequency constant for length extensional vibration becomes slightly small as the substrate thickness becomes thin, but it does not change as its length changes. Electro-mechanical coupling factor for length extensional vibration, k$\_$31/ does not change as its length changes within length/width$\geq$4, but it becomes small as its width increases.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.535-535
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• 2012

We present a new synthetic route and characterization for ultra small sized PbS quantum dots in extreme quantum confinement with 1.5 to 2.9 nm in diameter. We obtained a series of nanocrystals with first absorption wavelength ranging from 580 to 820 nm (2.1-1.5 eV). To get this result, PbS quantum dots size is finely controlled by adjusting the growth temperature in the range of $70-95^{\circ}C$. We demonstrate that photoluminescence (PL) shows a red shift with respect to the first absorption peak that increases with decreasing PbS quantum dots size and ranges from about 500 to 125 meV as the mean PbS quantum dots diameter increases from 1.5 to 2.9 nm. We further created the assembled PbS quantum dot solids and investigated the transport properties for energy applications.

• ETRI Journal
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• v.38 no.5
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• pp.879-884
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• 2016

In this paper, an ultra-small marker beacon antenna operated in the VHF-band is proposed. This antenna has a modified linear IFA structure with a lumped capacitor and a capacitive plate for frequency tuning and impedance matching. The capacitive plate is directly connected to the end of a linear radiator and is separated from the antenna ground by 1 mm. The main operating frequency is mainly controlled by the size and dielectric constant of the capacitive plate. The lumped capacitor is useful for fine frequency tuning. Using the proposed structure, an ultra-small marker beacon antenna can be realized with a length of 0.04 ${\lambda}_0$.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.591-596
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• 2000

The needs of ultra precision machined parts is increase every days. But the experimental data of nonferrous metal is insufficient. The cutting behavior in micro cutting area is different from that of traditional cutting because of the size effect. Al6061 is widely used as optical parts such as LASER reflector's mirror or multimedia instrument. Al6061 opper is machined by ultra precision machine with natural diamond tool. From the experiment and discussion on the cutting force and worked surface roughness as the variable spindle speed, feed rate and depth of cut. As a result, the cutting force increases as the increasing depth of cut, but the worked surface roughness does not increase so much. The surface roughness is good when spindle sped is above 1200rpm, and feed rate is small. The influence of depth of cut is very small.