• ETRI Journal
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• v.31 no.6
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• pp.778-783
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• 2009

To fabricate uniform and reliable thin gold stripes that provide low-loss optical waveguides, we developed a novel liftoff process placing an additional $SiN_x$ layer under conventional photoresists. By patterning a photoresist and over-etching the $SiN_x$, the photoresist patterns become free-standing structures on a lower-cladding. This leads to uniform metal stripes with good reproducibility and effectively removes parasitic structures on the edge of the metal stripe in the image reversal photolithography process. By applying the newly developed process to polymer-based gold stripe waveguide fabrication, we improved the propagation losses about two times compared with that incurred by the conventional image-reversal process.

• 전자공학회논문지 IE
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• v.48 no.2
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• pp.1-5
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• 2011

The epitaxial GaN layer of $120{\mu}m$ ~ $300{\mu}m$ thickness with a stripe Ti mask pattern is performed by hydride vapor phase epitaxy(HVPE). Ti strpie mask pattern is deposited by DC magnetron sputter on GaN epitaxial layer of $3{\mu}m$ thickness is grown by hydride vapor phase epitaxy(HVPE). Void are observed at point of Ti mask pattern when GaN layer is investigated by scanning electron microscope. The Crack of GaN layer is observed according to void when it is grown more thick GaN layer. The full width at half maximum of peak which is measured by X-ray diffraction is about 188 arcsec. It is not affected its crystallization by Ti meterial when GaN layer is overgrown on Ti stripe mask pattern according as it is measure FWHM of overgrowth GaN using Ti material against FWHM of first growth GaN epitaxial layer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.4
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• pp.145-150
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• 2014

GaN nanorods were grown on the apex of GaN stripes by three dimensional selective growth method. $SiO_2$ mask was partially removed only on the apex area of the GaN stripes by an optimized photolithography for the selective growth. Metallic Au was deposited only on the apex of the GaN stripes and a selective growth of GaN nanorods was followed by a metal organic vapor phase epitaxy (MOVPE). We confirmed that the shape and size of the GaN nanorods depend on growth temperature and flow rates of group III precursor. GaN nanorods were grown having a taper shape which have sharp tip and triangle-shaped cross section. From the TEM result, we confirmed that threading dislocations were rarely observed in GaN nanorods because of the very small contact area for the selective growth. Stacking faults which might be originated from a difference of the crystal facet directions between the GaN stripe and the GaN nanorods were observed in the center area of the GaN nanorods.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.1
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• pp.39-43
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• 2005

We proposed a structure for a 1.55 ㎛ strained separate confinement heterostructure (SCH) multi- quantum well (MQW) superluminescent diode (SLD), having a tapered active region. SLD was fabricated through a two-step procedure: the first step being metal organic chemical vapor deposition (MOCVD) and the second-step being liquid phase epitaxy (LPE). We used a 15 laterally tilted stripe and window region to suppress the lasing action of the SLD. The performance of the SLD showed output power of 11 mW with no lasing under 200 mA pulse driving. The full-width at half-maximum was 42 nm at 200 mA, 25℃.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.987-989
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• 2006

1.52" $130(RGB){\times}130$ full color PM OLED device with $70\;{\mu}m{\times}210\;{\mu}m$ of sub-pixel pitch was fabricated using shadow mask method for metal cathode deposition. Instead of conventional patterning process to form cathode separator via photolithography, regularly patterned shadow mask was applied to deposit metal cathode in this OLED display. Metal cathode was patterned via 2-step evaporation using shadow mask with shape of rectangular stripe and its alignment margin is $2.5\;{\mu}m$. Technical advantages of this method include reduction of process time according to skipping over photolithographic process for cathode separator and minimizing pixel shrinkage caused by PR cathode separator as well as improving lifetime of OLED device.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.1003-1011
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• 2020

This study aims to compare and evaluate the image differences between single and dual sources in applying a technique to reduce metal artifacts using dual energy CT. Discovery CT 256 (GE, USA) as a single source device and Somatom Definition Flash (Siemens Health Care, Forchheim, Germany) as a dual source device. The self-made phantom (pigs with medical titanium screws inserted) was quantitative and qualitatively evaluated under the same conditions by varying the dose under the same conditions using a dual energy CT. The evaluation method was compared by measuring SNR for metal artifacts (scattering, stripe) generated by metal inserts, divided around bones and around tissues. There was a difference in images in the method of reducing metal artifacts between single-source and dual-source devices. In a single source device, the linearized prosthesis by metal implantation showed a greater decrease than the image obtained from a double source device, and the surrounding tissue was well observed without interference from the artifact. In dual-source devices, scattering and stripe artifacts caused by metal inserts decreased more than on a single source device, and signals from adjacent tissues surrounding the metal implant were well observed without diminishing. If the examination is conducted separately between single source and dual source devices depending on whether the area to which the patient is intended to be viewed during the examination is adjacent to the metal insert or the total tissue surrounding the metal insert, it is believed that diagnostic helpful images can be obtained.

• Korean Journal of Materials Research
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• v.26 no.10
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• pp.528-534
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• 2016

The aim of this paper is to consider the effect of the manufacturing processes on corrosion and centerline cracking of ancient bronze spoons. The ancient bronze spoons in question were made by several steps of forging, in reheated condition with cast ingots. The manufacturing method is similar to that of the modern spoons. The investigations include observations from light and scanning electron microscopes of the microstructure in terms of the crack propagation. Cracks in the centerline are caused by solute segregation in the center-line region; this solute is solidified in the final stage of bronze spoon manufacture. Centerline cracking is also caused by ${\alpha}$ phase segregation, accompanied by forged overlapping along the longitudinal direction of the spoons. A vertical stripe with cracks along the centerline of the spoon's width is formed by folding in the wrought process. The overlapping area causes crack propagation with severe corrosion on the spoon surfaces over a period of a thousand years. The failure mechanisms of ancient bronze spoons may be similar to that of modern spoons, and the estimation of the failure mechanisms of ancient spoons can be appropriate to determine failure causes for such modern spoons.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.68-70
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• 2002

A CCD camera with a laser strip was applied to realize the automation of welding process in GMAW. The Hough transformation was used to extract the laser stripe and to obtain specific weld points. In this study, a neural network based on the generalized delta rule algorithm was adapted for the process control of GMA, such as welding speed, arc voltage and wire feeding speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.558-561
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• 2002

A CCD camera with a laser strip was applied to realize the automation of welding Process in GMAW. It takes relatively long time to process image on-line control using the basic Hough transformation, but it has a tendency of robustness over the noise such spatter and arc light. The adaptive Hough transformation was used to extract the laser stripe and to obtain specific weld points In this study, a neural network based on the generalized delta rule algorithm was adapted for the process control of GMA, such as welding speed, arc voltage and wire feeding speed.

• ETRI Journal
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• v.37 no.5
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• pp.951-960
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• 2015

For a conventional power metal-oxide-semiconductor field-effect transistor (MOSFET), there is a trade-off between specific on-state resistance and breakdown voltage. To overcome this trade-off, a super-junction trench MOSFET (TMOSFET) structure is suggested; within this structure, the ability to sense the temperature distribution of the TMOSFET is very important since heat is generated in the junction area, thus affecting its reliability. Generally, there are two types of temperature-sensing structures-diode and resistive. In this paper, a diode-type temperature-sensing structure for a TMOSFET is designed for a brushless direct current motor with on-resistance of $96m{\Omega}{\cdot}mm^2$. The temperature distribution for an ultra-low on-resistance power MOSFET has been analyzed for various bonding schemes. The multi-bonding and stripe bonding cases show a maximum temperature that is lower than that for the single-bonding case. It is shown that the metal resistance at the source area is non-negligible and should therefore be considered depending on the application for current driving capability.