• Journal of Electrical Engineering and information Science
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• v.2 no.4
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• pp.106-110
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• 1997

A new SOI NMOSFET with a 'LOCOS-like' shape self-aligned polysilicon gate formed on the recessed channel region has been fabricated by a mix-and-match technology. For the first time, a new scheme for implementing self-alignment in both source/drain and gate structure in recessed channel device fabrication was tried. Symmetric source/drain doping profile was obtained and highly symmetric electrical characteristics were observed. Drain current measured from 0.3${\mu}{\textrm}{m}$ SOI devices with V\ulcorner of 0.77V and Tox=7.6nm is 360$mutextrm{A}$/${\mu}{\textrm}{m}$ at V\ulcorner\ulcorner=3.5V and V\ulcorner=2.5V. Improved breakdown characteristics were obtained and the BV\ulcorner\ulcorner\ulcorner(the drain voltage for 1 nA/${\mu}{\textrm}{m}$ of I\ulcorner at V=\ulcorner\ulcorner=0V) of the device with L\ulcorner\ulcorner=0.3${\mu}{\textrm}{m}$ under the floating body condition was as high as 3.7 V. Problems for the new scheme are also addressed and more advanced device structure based on the proposed scheme is proposed to solve the problems.

• Progress in Medical Physics
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• v.3 no.1
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• pp.9-18
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• 1992

In this study, beta-eucryptite is fabricated and the thermal parameters of this material have been investigated. The thermoluminescence from 4MeV X-ray irradiated beta-eucryptite have been measured over the temperature range of 300K-600K. Thermoluminescence curve from X-ray irradiated beta-eucryptite shows five peaks located at 342K, 392K, 438K, 474K, and 527K. $\tau$, $\delta$ and $\omega$ of peak at 527K are 35K, 39K and 74K, respectively and this peak is found to be 2nd order kinetics. The activation energy of peak shape method is calculated to be 1.03eV and the frequency factor for 527K curve is calculated to be 3.9x10$\^$8/sec$\^$-1/. Based on the various heating rates methods, the activation energy of the peak is computed to be 1.02${\pm}$0.05eV that is similar to 1.19${\pm}$0.03eV of initial rise method. The linearity of thermoluminescence intensity and radiation flux is valid up to 50Gy and beyond higher dose the supralinearity and saturation come out.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.4
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• pp.279-286
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• 2014

Purpose: The aim of this study was to investigate the effect of implant thread profile on the marginal bone stresses which develop during implant insertion. Materials and methods: Four experimental implants were created by placing four different thread systems on the body ($4.1mm{\times}10mm$) of the ITI standard implant. The thread types studied in this study included the buttress, v-shape, reverse buttress, and square shape threads. In order to examine the insertion stress generation, 3D dynamic finite element analysis was performed which simulated the insertion process of implants into a 1.2 mm thick cortical bone plate (containing 3.5 mm pilot hole) using a PC-based DEFORM 3D (ver 6.1, SFTC, Columbus, OH, USA) program. Results: Insertion stresses higher than human cortical bone developed around the implants. The level of insertion stresses was much different depending on the thread. Stress level was lowest near the v-shape thread, and highest near the square shaped thread. Difference in the interfacial bone stress level was more noticeable near the valley than the tip of the threads. Conclusion: Among the four threads, the v-shape thread was turned out to minimize the insertion stress level and thereby create better conditions for implant osseointegration.

• Nuclear Engineering and Technology
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• v.2 no.4
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• pp.241-248
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• 1970

Neutron total cross sections of seperated isotopes were measured with the time-of-flight spectrometer at the 3 MeV Karlsruhe Van do Graaff Accelerator. The neutron energy ranged from 10 to 250 keV. The energy resolution was between 0.2 and 0.5 nsce/m. The measured cross sections were-shape-analyzed in terms of an R-matrix multilevel formula. Thus neutron widths and spins for up to 50 resonances per isotope could be determined. Average neutron widths, level densities and strength functions were derived. The spin dependence of strength functions and the distribution of widths and spacings were investigated.

• Journal of the Korean Society of Safety
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• v.17 no.2
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• pp.112-117
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• 2002

The effects of shield gas on the structure of methane-air nonpremixed counterflow flames were numerically investigated. The near extinction flame of a low global strain rate 20 $s^{-1}$ of 19% methane diluted by 81% nitrogen by volume and undiluted air was computed. The flame shape, centerline temperature and axial velocity profiles were compared for different velocity of the shield gas and with and without the shield gas. The effects of the velocity of the shield gas were negligible for $V_{S}/V_{F}{\leq}2$ in normal gravity. Under normal gravity conditions, the flame shape and its position with the shield gas were different from those of the flame without the shield gas, whereas no discernible effects of the shield gas along the centerline were observed in zero gravity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1349-1356
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• 1994

The results of laboratory experiments on the clear-water scour of cohesionless bed sediment for three types of pier shape were presented. According to the experimental data, the local scouring around the pier was initiated at $V/V_c=0.4{\sim}0.5$ and $Fr_p{\fallingdotseq}0.2$, and the relative local scour depths linearly increased with respect to the velocity ratio and the pier Froude number. The relative scour depth had the linear relationship with ${\tau}_r$ for ${\tau}_r$ < $10^{-4}$, but it tends to become constant for ${\tau}_r$ > $10^{-4}$, irrespective of ${\tau}_r$. And also the relative scour depths showed the close relationship with both the geometric standard deviation and the pier shape.

• Journal of IKEEE
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• v.17 no.3
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• pp.221-228
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• 2013

About functional parameters of a LED/UVLED (Light Emitting Diode/Ultra Violet LED), one of the most important parameters is the I-V characteristic. By researching factors affect to the I-V characteristic of uvled, we found that beside of the structure of the device itself, there is the influence of the electrode materials, electrode shapes, the process of wiring and packaging. In this work, we want to improve the performance of UVLED to find out the optimal mask design principles. The study is based on theoretical mathematical models, as well as the use of simulation software tool Comsol. From all results obtained, the team has improved mask design to manufacture electrodes for GaN-based UVLED. Electrode masks are designed by three softwares, which are Intellisuite, Klayout and AutoCad. Intellisuite masks would be used in fabrication simulation while Klayout and AutoCad are used to fabricate electrodes in experiments. As well as, we silmulated the structure of an uvled 355nm emission wavelength by TCAD software, in order to compare with uvled sample that has the same emission wavelength.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.101-104
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• 2008

The sailfish is the fastest sea animal, reaching its maximum speed of 110km/h. On its skin, a number of V-shaped protrusions pointing downstream exist. Thus, in the present study, the possibility of reducing the skin friction using its shape is investigated in a turbulent boundary layer. We perform a parametric study by varying the height and width of the protrusion, the spanwise and streamwise spacings between adjacent ones, and their overall distribution pattern, respectively. Each protrusion induces a pair of streamwsie vortices, producing low and high shear stresses at its center and side locations, respectively. These vortices also interact with those induced from adjacent protrusions. As a result, the drag is either increased or unchanged for all the cases considered. In some cases, the skin friction itself is reduced but total drag including the form drag on the protrusions is larger than that of a smooth surface. Since the shape of present protrusions is similar to that used by Sirovich and Karlsson [Nature 388, 753 (1997)] where V-shaped protrusions pointing upstream were considered, we perform another set of experiments following their study. However, we do not obtain any drag reduction even with random distribution of those V-shaped protrusion.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.119-119
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• 2016

Over the last years the anodic formation of ordered $TiO_2$ nanotube layers has created significant scientific interest. Titanium oxide nanotube formation on the titanium or titanium alloy surface is expected to be important to improve cell adhesion and proliferation under clinical conditions. It should be possible to control the nanotube size and morphology for biomedical implant use by controlling the applied voltage, alloying element, current density, anodization time, and electrolyte. $TiO_2$ nanotubes show excellent biocompatibility, and the open volume in the tubes may be exploited as a drug release platform and so on. Therefore, in this study, Nanotube shape on the Ti-29Nb-xHf alloys with applied potentials was reserched. $TiO_2$ nanotube formation on Ti-29Nb-xHf alloys was carried out using anodization technique as a function of applied DC potential (10 V to 30 V and 30 V to 10 V) and anodization time for 60~120 min in $1MH_3PO_4$ with small additions of (0.8 wt. %, to 1.2 wt. %) NaF. The morphology change of anodized Ti-29Nb-xHf alloys was determined by FE-SEM, XRD, and EDS.

• Journal of Powder Materials
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• v.26 no.4
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• pp.311-318
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• 2019

The objective of this study is to investigate the influence of powder shape and densification mechanism on the microstructure and mechanical properties of Ti-6Al-4V components. BE powders are uniaxially and isostatically pressed, and PA ones are injection molded because of their high strengths. The isostatically compacted samples exhibit a density of 80%, which is higher than those of other samples, because hydrostatic compression can lead to higher strain hardening. Owing to the higher green density, the density of BE-CS (97%) is found to be as high as that of other samples (BE-DS (95%) and P-S (94%)). Furthermore, we have found that BE powders can be consolidated by sintering densification and chemical homogenization, whereas PA ones can be consolidated only by simple densification. After sintering, BE-CS and P-S are hot isostatically pressed and BE-DS is hot forged to remove residual pores in the sintered samples. Apparent microstructural evolution is not observed in BE-CSH and P-SH. Moreover, BE-DSF exhibits significantly fine grains and high density of low-angle grain boundaries. Thus, these microstructures provide Ti-6Al-4V components with enhanced mechanical properties (tensile strength of 1179 MPa).