• Journal of Power Electronics
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• v.6 no.1
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• pp.18-28
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• 2006

The Electric Power Subsystem (EPS) is one of the most critical systems on any satellite because nearly every subsystem requires power. This makes the choice of power systems the most important task facing satellite designers. The main purpose of the Satellite EPS is to provide continuous, regulated and conditioned power to all the satellite subsystems. It has to withstand radiation, thermal cycling and vacuums in hostile space environments, as well as subsystem degradation over time. The EPS power characteristics are determined by both the parameters of the system itself and by the satellite orbit. After satellite separation from the launch vehicle (LV) to its orbit, in almost all situations, the satellite subsystems (attitude determination and control, communication and onboard computer and data handling (OBC&DH)), take their needed power from a storage battery (SB) and solar arrays (SA) besides the consumed power in the EPS management device. At this point (separation point, detumbling mode), the satellite's angular motion is high and the orientation of the solar arrays, with respect to the Sun, will change in a non-uniform way, so the amount of power generated by the solar arrays will be affected. The objective of this research is to select satellite EPS component types, to estimate solar array illumination parameters and to determine the efficiency of solar arrays during both detumbling and normal operation modes.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.155-158
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• 2007

Printed organic thin-film transistor(OTFT) to use as a switching device for an organic light emitting diode(OLED) were fabricated in the microcontact printing and direct printing processes at room temperature. The gate electrodes($5{\mu}m$, $10{\mu}m$, and $20{\mu}m$) of OTFT was fabricated using microcontact printing process, and source/drain electrodes ($W/L=500{\mu}m/5{\mu}m$, $500{\mu}m/10{\mu}m$, and $500{\mu}m/20{\mu}m$) was fabricated using direct printing process with hard poly(dimethylsiloxane)(h-PDMS) stamp. Printed OTFT with dielectric layer was formed using special coating system and organic semiconductor layer was ink-jet printing process. Microcontact printing and direct printing processes using h-PDMS stamp made it possible to fabricate printed OTFT with channel lengths down to $5{\mu}m$, and reduced the process by 20 steps compared with photolithography. As results of measuring he transfer characteristics and output characteristics of OTFT fabricated with the printing process, the field effect characteristic was verified.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.96-98
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• 1999

유기전계발광소자(OELD)의 성능 향상을 위한 많은 연구가 진행되고 있지만 아직까지 금속전극과 유기발 광층 사이의 접촉저항(Contact Resistance)에 관한 연구는 거의 보고되지 않고 있다. Ohmic 접합에서 접촉 저항은 효율적이고 신뢰성 있는 소자제작에 있어서 간과되어서는 안될 매우 중요한 부분이다. 본 연구에서는 금속전극과 유기발광충 사이의 접촉저항에 관해서 논의하고자 한다. 본 연구에서 제작된 샘플은 금속전극으로 Ag, 유기발광재료로서 Alq$_3$를 사용하였으며, Alq3의 두께를 100 $\AA$에서 500 $\AA$까지 각각 다르게 하여 서로 다른 두께의 유기발광층을 가지는 샘플을 제작하였다. 금속전극의 매트릭스 구조에 의해 형성된 적선의 크기는 3 mm x 2 mm이며, 제작된 샘플의 접촉비저항은 TLM(Transmission Line Measurement) 방법을 이용하여 구하였다. Planar한 TLM model로부터 새로운 vertical model을 유추하였으며, 이를 근거로 접촉저항 및 transfer length 등을 계산하였다. 상온에서 측정된 전체 저항값은 유기발광층의 두께가 증가함 에 따라 증가하는 경향을 나타냈으며, 이 때 계산된 접촉비저항은 1.49$\times$$10^1$ $\Omega$-$\textrm{cm}^2$ 이다. 접촉저항은 전극 사이의 거리의 증가에 따라 증가하지만, 측정시간의 thermal budget의 영향으로 상대적으로 전체저항이 감 소하였으나, 저항감소분의 포화에 따라서, 거리에 비례하여 다시 저항이 증가하였다.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1772-1775
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• 2000

We have fabricated poly-Si TFTs by two-step crystallizaton. Poly-Si films have been prepared by furnace annealing(FA) and rapid thermal annealing(RTA) followed by subsequent the post-annealing, excimer laser annealing. The measured crystallinity of RTA and FA annealed poly-Si film is 77% and 68.5%, respectively. For two-step annealed poly-Si film, the crystallinity has been drastically to 87.7% and 86.3%. The RMS surface roughness from AFM results have been improved from 56.3${\AA}$ to 33.5${\AA}$ after post annealing. The measured transfer characteristics of the two-step annealed poly-Si TFTs have been improved significantly for the both FA-ELA and RTA-ELA. Leakage currents of two-step annealed poly-Si TFTs are lower than that of the devices by FA and RTA. From these results, we can describe the fact that the intra-grain defects has been cured drastically by the post-annealing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.9
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• pp.801-810
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• 2014

In this paper, we will provide a way to grant a differentiated service rate that is according to priorities of WLP device and WUSB/DRD transfer mode by improving D-SoQ that considers existing QoS of WiMedia WSS environment based on UWB technology. The proposed method makes it possible to differentiate SoQ performance and throughput, based on priority of traffic streams.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.19-31
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• 2005

During the last decade, the exploration of nanoscale device and circuitry based on molecules has gained increasing interest. In parallel with this, considerable effort is being devoted to the development of molecular photonic/electronic materials based on various porphyrin arrays. This involves light as an input/output signal and excitation energy migration as a mechanism for signal transmission. Absorption of a photon at the light collector end of the porphyrin array yields the excited state, which migrates among the intervening pigments until reaching the emitter, whereupon another photon is emitted. As a consequence, it is relevant to understand the excitation energy transfer (EET) processes occurring in various forms of porphyrin arrays for the applications as artificial light harvesting arrays and molecular photonic/electronic wires. Since the excitonic (dipole) and electronic (conjugation) couplings between the adjacent porphyrin moieties in porphyrin arrays govern the EET processes, we have characterized the EET rates of various forms of multiporphyrin arrays (linear, cyclic, and box) based on various time-resolved spectroscopic measurements. We believe that our observations provide a platform for further development of molecular photonic/electronic materials based on porphyrin arrays.

• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.311-319
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• 2017

By using Density Functional Theory (DFT), we have performed alkali metal and alkaline earth metal inside fullerene-like BeO cluster (FLBeOC) in terms of energetic, geometric, charge transfer, work function and electronic properties. It has been found that encapsulated processes of the alkali metal are exothermic and thermodynamically more favorable than alkaline earth metal encapsulation, so that interaction energy ($E_{int}$) of the alkali metal encapsulation FLBeOC is in the range of -0.02 to -1.15 eV at level of theory. It is found that, the electronic properties of the pristine fullerene-like BeO cluster are much more sensitive to the alkali metal encapsulation in comparison to alkaline earth metal encapsulation. The alkali and alkaline earth metal encapsulated fullerene-like BeO cluster systems exhibit good sensitivity, promising electronic properties which may be useful for a wide variety of next-generation nano-sensor device components. The encapsulation of alkali and alkali earth metal may increase the electron emission current from the FLBeOC surface by reducing of the work function.

• The Journal of the Acoustical Society of Korea
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• v.34 no.2
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• pp.108-116
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• 2015

An acoustic vector sensor is a device that is capable of measuring the direction of wave propagation and the acoustic pressure. In this paper, the modeling of micro-cantilever sensor for the vector sensor are proposed by consideration of acoustic phenomenon in water. Two models based on unimorph structure are proposed in this paper and corresponding transfer function which describes the relation between input pressure wave and output voltage depending on incidence angle and frequency of pressure wave is derived based on lumped model. It has been shown that very thin and flexible micro-cantilever can be used to measure directly the particle velocity component in water.

• Journal of the Korean Magnetics Society
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• v.22 no.4
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• pp.136-141
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• 2012

In the this research, two simultaneous peaks of radial artery pulse wave and ECG pulse wave measured by using clip-type pulsimeter and ECG were investigated in order to analyze pulse wave velocity. The measured value of a pulse wave velocity is about 5~7 m/s, it is proved one new method to measure an exact value of pulse wave velocity more than the typical biomedical signal monitoring system. This result implies that data measured by the oriental medical diagnosis apparatus as pulsimeter is clinically used in future.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.540-548
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• 2019

This study was conducted to develop insulation for solid oxide fuel cell (SOFC). The developed insulation is based on the lamination technology and the radiation shielding technology of the satellite insulation. The insulation material is consisting of insulation material for conduction resistance, spacer, and radiation shielding material. The experimental apparatus consisting vacuum bell jar, pump, heater and temperature recording device has developed to verify the performance of the insulation. The experimental values were used as reference data for the modeling development. In this paper, heat transfer is assumed to be one- dimensional phenomena for the prediction of insulation performance and internal temperature distribution in high temperature region of SOFC. The developed model was used to compare the performance difference of insulation types according to composition materials. The analysis result shows that the insulation including spacer and radiation shielding has better heat insulation performance than other cases. In this study, the thickness reduction effect of about 20% was shown compared to the insulation including only conductive material. It is noted that the radiant shielding material should be carefully selected for durability, because SOFC insulation should be used for a long time at high temperature.