• Korean Journal of Materials Research
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• v.8 no.4
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• pp.288-292
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• 1998

The p*-n ultra shallow junction diode with Co/Ti bilayer silicide was formed by ion implantation of $BF_{2}$ energy : 30KeV, dose : $5\times10^{15}cm^{-2}$] onto the n-well Si(100) region and RTA-silicidation of the evaporated Co($120\AA$)/Ti($40\AA$) double layer. The fabricated diode exhibited ideality factor of 1.06, specific contact resistance of $1.2\times10^{-6}\Omega\cdot\textrm{cm}^2$ and leakage current of $8.6\muA/\textrm{cm}^2$(-3V) under the reverse bias of 3V. The sheet resistance of silicided emitter region, the boron concentration at silicide/Si interface and the junction depth including silicide layer of ($500\AA$ were about $8\Omega\Box$, $6\times10^{19}cm^{-3}$, and $0.14\mu{m}$, respectively. In the fabrication of diode, the application of Co/Ti bilayer silicide brought improvement of ideality factor on the current-voltage characteristics as well as reduction of emitter sheet resistance and specific contact resistance, while it led to a little increase of leakage current.

• Korean Journal of Remote Sensing
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• v.31 no.6
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• pp.531-548
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• 2015

Atmospheric Motion Vector (AMV) from satellite images have shown Slow Speed Bias (SSB) in comparison with rawinsonde. The causes of SSB are originated from tracking, selection, and height assignment error, which is known to be the leading error. However, recent works have shown that height assignment error cannot be fully explained the cause of SSB. This paper attempts a new approach to examine the possibility of SSB reduction of COMS AMV by using a new target tracking algorithm. Tracking error can be caused by averaging of various wind patterns within a target and changing of cloud shape in searching process over time. To overcome this problem, Gaussian Mixture Model (GMM) has been adopted to extract the coldest cluster as target since the shape of such target is less subject to transformation. Then, an image filtering scheme is applied to weigh more on the selected coldest pixels than the other, which makes it easy to track the target. When AMV derived from our algorithm with sum of squared distance method and current COMS are compared with rawindsonde, our products show noticeable improvement over COMS products in mean wind speed by an increase of $2.7ms^{-1}$ and SSB reduction by 29%. However, the statistics regarding the bias show negative impact for mid/low level with our algorithm, and the number of vectors are reduced by 40% relative to COMS. Therefore, further study is required to improve accuracy for mid/low level winds and increase the number of AMV vectors.

• 한국노년학
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• v.38 no.1
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• pp.83-102
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• 2018

According to socioemotional selectivity theory, if people perceive their time left in life as expanded, they have a future-oriented goal of life, but if perceive as limited the goal of life is changed into the pursuit of present emotional satisfaction. Thus, if we perceive our time left as getting limited as we get older, we pay more attention to the positive stimuli than the negative ones and remember more the positive stimuli in order to maintain the current emotional state as positive. This is known as the positivity effect. This study examined whether the positivity effect is caused by a limited future time perspective. The participants were presented with scenarios for hypothetical situations in which the future time was expanded or limited, and were encouraged to immerse in the virtual situation by talking about what they would like to do and whom they wanted to spend time with. Then the participants were presented with 48 positive, negative, and neutral emotional pictures and were asked to recall after 10 minutes delay. 75 university students and 65 elderly participated in the study. In the control condition where the future time perspective was not manipulated, the elderly showed the positivity effect but the youth showed the bias toward negative pictures. The elderly in the expanded time condition recalled positive pictures less and negative pictures more than the elderly in the control condition. On the other hand, the youth in the limited time condition recalled less the negative pictures than the youth in the control condition. These results demonstrated that the elderly did not show the positive bias when the future time perspective was expanded, and that the youth showed the positive bias when the future time perspective was limited. These results show that the positivity effect is related with the limited future time perspective.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.902-911
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• 2003

Using InGaP/GaAs HBT power cells with a 2.0${\times}$20$\mu\textrm{m}$$^2$ emitter area of a unit HBT, a two stage MMIC power amplifier has been developed for IMT-2000 handsets. An active-bias circuit has been used for temperature compensation and reduction in the idling current. Fitting on measured S-parameters of the HBT cells, circuit elements of HBT's nonlinear equivalent model have been extracted. The matching circuits have been designed basically with the extracted model. A two stage HBT MMIC power amplifier fabricated using ETRI's HBT process. The power amplifier produces an 1-㏈ compressed output power(P$\_$l-㏈/) of 28.4 ㏈m with 31% power added efficiency(PAE) and 23-㏈ power gain at 1.95 GHz in on-wafer measurement. Also, the power amplifier produces a 26 ㏈m output power, 28% PAE and a 22.3-㏈ power gain with a -40 ㏈c ACPR at a 3.84 ㎒ off-center frequency in COB measurement.quency in COB measurement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.365-371
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• 2002

In this paper, the fabricated power PHEMT devices for millimeter-wave that is below a gate-length of 0.2 $\mu\textrm{m}$ using electronic beam lithography technologies, and the DC and frequency characteristics and an output power characteristics were Measured at the various bias conditions. The unit process that is used in PHEMT's manufacture used that low-resistance ohmic contact, air-bridge and back-side lapping process technologies, and so on. The fabricated power PHEMT have an S521 gain of 4 dB and a maximum transconductance(gm) of 317 mS/mm, an unilateral current gain(fT) of 62 GHz, a maximum oscillation frequency(fmax) of 120 GHz at 35 GHz, and a maximum power output(Pmax) of 16 dBm, a power gain(GP) of 4 dB and a drain efficiency(DE) of 35.5 %.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.626-631
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• 2005

GaN-related compound semiconductors were grown on the corrugated interface substrate using a metalorganic chemical vapor deposition system to increase the optical power of white LEDs. The patterning of substrate for enhancing the extraction efficiency was processed using an inductively coupled plasma reactive ion etching system and the surface morphology of the etched sapphire wafer and that of the non-etched surface were investigated using an atomic force microscope. The structural and optical properties of GaN grown on the corrugated interface substrate were characterized by a high-resolution x-ray diffraction, transmission electron microscopy, atomic force microscope and photoluminescence. The roughness of the etched sapphire wafer was higher than that of the non-etched one. The surface of III-nitride films grown on the hemispherically patterned wafer showed the nano-sized pin-holes that were not grown partially. In this case, the leakage current of the LED chip at the reverse bias was abruptly increased. The reason is that the hemispherically patterned region doesn't have (0001) plane that is favor for GaN growth. The lateral growth of the GaN layer grown on (0001) plane located in between the patterns was enhanced by raising the growth temperature ana lowering the reactor pressure resulting in the smooth surface over the patterned region. The crystal quality of GaN on the patterned substrate was also similar with that of GaN on the conventional substrate and no defect was detected in the interface. The optical power of the LED on the patterned substrate was $14\%$ higher than that on the conventional substrate due to the increased extraction efficiency.

• International Journal of Oral Biology
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• v.34 no.4
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• pp.191-197
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• 2009

Somatostatin (SST) is a known neuromodulator of the central nervous system. The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) receives many thinmyelinated $A{\delta}$-fiber and unmyelinated C primary afferent fibers and is involved in nociceptive processing. Many studies have demonstrated that SST plays a pivotal role in pain modulation in the spinal cord. However, little is yet known about the direct effects of SST on the SG neurons of the Vc in adult mice. In our present study, we investigated the direct membrane effects of SST and a type 2 SST receptor agonist, seglitide (SEG), on the SG neurons of the Vc using a gramicidin-perforated current clamp in adult mice. The majority (53%, n = 27/51) of the adult SG neurons were hyperpolarized by SST (300 nM) but no differences were found in the hyperpolarization response rate between males and females. When SST was applied successively, the second response was smaller ($76{\pm}9.5%$, n=19), suggesting that SST receptors are desensitized by repeated application. SST-induced hyperpolarization was also maintained under conditions where presynaptic events were blocked ($75{\pm}1.0%$, n=5), suggesting that this neuromodulator exerts direct effects upon postsynaptic SG neurons. SEG was further found to induce membrane hyperpolarization of the SG neurons of the Vc. These results collectively demonstrate that SST inhibits the SG neuronal activities of the Vc in adult mice with no gender bias, and that these effects are mediated via a type 2 SST receptor, suggesting that this is a potential target for orofacial pain modulation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.41-46
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• 2012

A quadrature voltage controlled oscillator(QVCO) for X-band is presented in this paper. The QVCO has fabricated in Charted $0.13{\mu}m$ CMOS process. The QVCO consists of two cross-coupled differential VCO and two differential buffers. The QVCO is controlled by 4 bit of capacitor bank and control voltage of varactor. To have a linear quality factor of varactors, voltage biases of varactors are difference. The QVCO generates frequency tuning range from 6.591 GHz to 8.012 GHz. The phase noise is -101.04 dBc/Hz at 1MHz Offset when output frequency is 7.150 GHz. The supply voltage is 1.5 V and core current 6.5-8.5 mA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1149-1154
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• 2014

To observe the tunneling phenomenon of oxide semiconductor transistor, The Indium-gallum-zinc-oxide thin film transistors deposited on SiOC as a gate insulator was prepared. The interface characteristics between a dielectric and channel were changed in according to the properties of SiOC dielectric materials. The transfer characteristics of a drain-source current ($I_{DS}$) and gate-source voltage ($V_{GS}$) showed the ambipolar or unipolar features according to the Schottky or Ohmic contacts. The ambipolar transfer characteristics was obtained at a transistor with Schottky contact in a range of ${\pm}1V$ bias voltage. However, the unipolar transfer characteristics was shown in a transistor with Ohmic contact by the electron trapping conduction. Moreover, it was improved the on/off switching in a ambipolar transistor by the tunneling phenomenon.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.301-303
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• 2012

We present the result of our near infrared J- (${\lambda}=1.25{\mu}m$), H- (${\lambda}=1.63{\mu}m$), and $K_s$-band (${\lambda}=2.14{\mu}m$) imaging of ultraluminous ($L_{IR}$ > $10^{12}L_{\odot}$) and luminous ($L_{IR}=10^{11-12}L_{\odot}$) infrared galaxies (ULIRGs and LIRGs), to investigate their relationship through properties of their host galaxies. We find that (1) for single-nucleus ULIRGs and LIRGs, their spheroidal host galaxies have similar properties, but ULIRGs display a substantially higher level of nuclear activity than LIRGs, suggesting that their infrared luminosity difference comes primarily from the different level of current nuclear activity. We infer that LIRGs and ULIRGs have similar progenitor galaxies, follow similar evolutionary processes, and may evolve into optically-selected QSOs. (2) Largely-separated multiple-nuclei ULIRGs have significantly brighter host galaxies than single-nucleus ULIRGs and LIRGs in $K_s$-band, indicating that multiple-nuclei ULIRGs have a bias towards mergers of intrinsically large progenitor galaxies, in order to produce high infrared luminosity ($L_{IR}$ > $10^{12}L_{\odot}$) even at the early merging stage. (3) We derive dust extinction of host galaxies of ULIRGs and LIRGs to be $A_V$ ~ 14 mag in the optical or equivalently $A_K$ ~ 0.8 mag in the near-infrared $K_s$-band, based on the comparison of host galaxy's luminosities in the J-, H-, and $K_s$-bands.