• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.1-7
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• 2004

In order to enhance the electron mobility in SOI n-MOSFET, we fabricated fully depletion(FD) n-MOSFET on the strained Si/relaxed SiGa/SiO$_2$/Si structure(strained Si/SGOI) formed by inserting SiGe layer between a buried oxide(BOX) layer and a top silicon layer. The summated thickness of the strained Si and relaxed SiGe was fixed by 12.8 nm and then the dependency of electron mobility on strained Si thickness was investigated. The electron mobility in the FD n-MOSFET fabricated on the strained Si/SGOI enhanced about 30-80% compared to the FD n-MOSFET fabricated on conventional SOI. However, the electron mobility decreased with the strained Si thickness although the inter-valley phonon scattering was reduced via the enhancement of the Ge mole fraction. This result is attributed to the increment of intra-valley phonon scattering in the n-channel 2-fold valley via the further electron confinement as the strained Si thickness was reduced.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.119-126
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• 2007

Recently, the mobility of users and mobile communication technologies have developed rapidly. The users in this state also want to connect their devices and to receive services anywhere, anytime. Hierarchical Mobile IPv6 (HMIPv6) has been proposed by the Internet Engineering Task Force (IETF) to compensate for such problems as handover latency and signaling overhead when employing Mobile IPv6 (MIPv6). HMIPv6 supports micro-mobility within a domain and introduces a new entity, namely Mobility Anchor Point (MAP) as a local home agent. However, HMIPv6 has been found to cause longer handover latency when the inter-domain handover occurs. This is because a Mobile Node (MN) has to generate two addresses and register them to Home Agent (HA) a MAP, respectively. In order to solve such problems, we propose a scheme that an MN generates one address and registers it to HA for supporting fast handover during the inter-domain handover process. In the proposed scheme, the load of MAP and MAP domain is reduced because the number of MNs which are managed by MAP is decreased and the MAP does not perform proxy Neighbor Discovery Protocol (NDP) to intercept packets destined to MNs. We evaluate the performance of proposed scheme in comparison to HMIPv6 through the simulation and numerical analysis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.2 s.344
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• pp.16-21
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• 2006

Internet Engineering Task Force(IETF) proposed the Hierarchical Mobile IPv6(HMIPv6) to support mobility efficiently. The HMIPv6 was developed to reduce the signaling overhead and delay concerned with Binding Update in Mobile IPv6. However, the HMIPv6 still need a further enhancement for supporting the real-time application because HMIPv6 only concerns with the latency resulted within a MAP For providing seemless handoff we propose a scheme that can reduce latency when Mobile Node changes a MAP. Also we compare the HMIPv6 with the proposed scheme through a analysis model.

• Journal of Environmental Science International
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• v.21 no.11
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• pp.1339-1348
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• 2012

The versatile aerosol concentration enrichment system (VACES) have proven useful for providing elevated levels of atmospheric aerosol to human and animal exposures. In this study, we describe a VACES and tests conducted to both optimize the enhancement factor (EF) and characterize how it depends on experiment conditions. Particle number concentrations were measured from upstream and downstream of the system by scanning mobility particle sizer (SMPS) with a long differential mobility analyzer (DMA) in combination with a condensation particle counter (CPC). SMPS was used for to determine VACES particle EF. Particle EF tends to increase for higher the saturator temperature ($T_{Sat}$) and lower the condenser temperature ($T_{Con}$). $T_{Con}$ higher than $0^{\circ}C$ and $T_{Sat}$ lower than $50^{\circ}C$ was the best to obtain the most increase in particle concentration. Correlation analysis of EF with factor variables of $T_{Sat}$ and $T_{Con}$ resulted in correlation 0.662 and 0.416, respectively. With all five predictor variables included in a multiple regression model, the EF had a liner correlation with $R^2=0.643$.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.494-498
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• 2003

In this paper, the plasma treatment on gate surface has been applied prior to deposition of pentacene and the effects on performance were investigated. The Plasma treatment produced the mobility of 0.05$\textrm{cm}^2$/V.sec which is 10 times larger than the non-treated. The resistance was also reduced from 400K$\Omega$ to 50K$\Omega$. In addition, the standard deviation of performance parameters variation was reduced with the plasma exposure time, which implies that plasma treatment makes the gate surface states be uniform across the whole wafer area. The performance parameters were increased with the exposure time up to 5min, after which they degraded again. Therefore, the optimal exposure time was found to be 5min.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.793-798
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• 2007

During May of 2003, smoke from fires in the Yucatan Peninsula was transported across the Gulf of Mexico and into Texas where it caused significant enhancement in measured aerosol concentrations and reduced visibility. During this event, the formation and growth of aerosol particles has been observed by a differential mobility analyzer (DMA) / tandem differential mobility analyzer (TDMA) system to characterize the size distribution and size-resolved hygroscopicity of the aerosol. The most number concentration is by the particles smaller than 100 nm, but the integrated number concentrations for over 100 nm increased due to the aerosol growth. Hygroscopic growth factor increase from 1.2 to 1.4 for 25, 50, and 100 nm particles during the nucleating period. This distribution and the aerosol properties derived from the TDMA data were used to calculate the growth rate. Particle growth rates were in the range 1-12 nm/hr.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.34-35
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• 2006

Transparent ZnO thin film transistor (TFT) is fabricated on the glass substrates. The device consists of a high mobility intrinsic ZnO as a semiconductor active channel, Ga doped ZnO (GZO) as an electrode, $HfO_2$ as a gate insulator. GZO and $HfO_2$ layers are prepared by using a pulsed laser deposition and intrinsic ZnO layers are fabricated by using an rf-magnetron sputtering, respectively. The transparent TFT is highly transparent (> 87 %) and exhibits n-channel, enhancement mode behavior with a field-effect mobility as large as $11.7\;cm^2/Vs$ and a drain current on-to-off ratio of about $10^5$.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.282-295
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• 2007

Due to the nature that high datarate leads to shorter transmission range, the performance enhancement by high datarate 802.11 WLANs may be degraded when applying high datarate to an 802.11 based multihop ad hoc network. In this paper, we evaluate, through extensive simulations, the performance of multihop ad hoc networks at multiple transmission datarates, in terms of the number of hops between source and destination, throughput, end-to-end delay and packet loss. The study is conducted based on both stationary chain topology and mesh topologies with or without node mobility. From numerical results on network performance based on chain topology, we conclude that there is almost no benefit by applying the highest datarate when the chain length is 6 hops or more. With node mobility in mesh topology, the benefit of using high datarate diminishes at even shorter number of hops. To explore the main reasons for this behavior, analyses on multihop end-to-end throughput and network k-connectivity have been conducted later in the paper, and correspondingly an auto-rate adaptation algorithm has been proposed.

• Journal of Surface Science and Engineering
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• v.54 no.2
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• pp.90-95
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• 2021

Surface modification technique enabling the control of condensation provides various benefit in various engineering systems, such as heat transfer, desalination, power plants, and so on. In this study, lubricant oil-impregnation into Teflon-coated nanoporous anodic oxide layer of aluminum to enhance a de-wetting and mobility of water droplet on surface. Due to the surface treatment improving water-repellency, the condensation mode is changed to dropwise, thus the frequency of sliding condensed water droplet on surface is increased. For these reasons, the surface of oil-impregnated Teflon-coated nanoporous anodic aluminum oxide shows significantly enhanced condensation heat transfer compared to bare aluminum surface. In addition, the porosity of anodic aluminum oxide affected the mobility of water droplet even with oil-impregnation and Teflon-coating, indicating that the optimization of porous structure of anodic oxide is required for maximizing the condensation heat transfer.

• Journal of Surface Science and Engineering
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• v.56 no.1
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• pp.1-11
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• 2023

Lubricant-impregnated nanoporous surfaces (LIS), which is created by impregnating water-immiscible oil into nanoporous surface structure, have been explored considering wide range of application fields. Due to the lubricant impregnated in nanoporous structure, the surface shows extreme de-wetting with a high mobility of water droplets, so that various functionalities can be realized. The lubricant layer inhibits the contact of corrosive media to porous structure as well as metal substrate, thus the surface improves the corrosion resistance. The water on the surface freeze without any contact to solid porous structure, showing a low ice adhesion for de-icing an anti-icing. The extremely high mobility of water droplets on lubricant-impregnated porous surfaces also contributes the enhancement of condensation heat transfer as well as water harvesting from fog and moisture. Moreover, the bacteria adhesion on metal surface forming biofilms causing serious hygiene issues can be inhibited on the lubricantimpregnated surfaces. Despite of such superior functionalities, the lubricant-impregnated porous surface has a limitation of lubricant depletion by external flow of fluids. Therefore, extensive efforts to improve the durability of lubricant-impregnated surface are required for practical applications.