• 한국재료학회지
• /
• 제20권1호
• /
• pp.47-50
• /
• 2010

Various thicknesses of Al-doped ZnO (AZO) films were deposited on glass substrate using pulsed dc magnetron sputtering with a cylindrical target designed for large-area high-speed deposition. The structural, electrical, and optical properties of the films of various thicknesses were characterized. All deposited AZO films have (0002) preferred orientation with the c-axis perpendicular to the substrate. Crystal quality and surface morphology of the films changed according to the film thickness. The samples with higher surface roughness exhibited lower Hall mobility. Analysis of the measured data of the optical band gap and the carrier concentration revealed that there were no changes for all the film thicknesses. The optical transmittances were more than 85% regardless of film thickness within the visible wavelength region. The lowest resistivity, $4.13\times10^{-4}\Omega{\cdot}cm^{-1}$ was found in 750 nm films with an electron mobility $(\mu)$ of $10.6 cm^2V^{-1} s^{-1}$ and a carrier concentration (n) of $1.42\times10^{21} cm^{-3}$.

• 한국ITS학회 논문지
• /
• 제16권6호
• /
• pp.156-168
• /
• 2017

개인교통수단(PM)은 개인의 이동편의를 향상시켜준다는 측면에서 보행능력이 떨어지는 고령자가 주요 활용 대상이 될 수 있다. 본 연구에서는 고령자가 보도 등 보행환경에서 안전하게 이용할 수 있는 개인교통수단을 설계하고자 한다. 보행환경에는 다양한 통행 장애요인이 존재하며, 개발하고자 하는 수단은 장애요인을 극복하기 위한 기기 성능이 확보되어야 한다. 본 연구에서는 고령자용 개인교통수단의 성능수준 결정을 위하여 보행환경 상 통행 장애요인 현황 및 수준을 조사한다. 관련 지침을 검토하여 조사 대상 항목 및 조사 방법론을 정의하고, 고령자 일상생활 기반 통행 시나리오를 통해 선정된 특정 도로구간에 대하여 조사를 수행한다. 조사 결과를 바탕으로 수단의 기기 성능을 지침 상 제시된 기준에 근거하여 확보하였을 때 발생 가능한 문제점을 확인하며, 장애인용 전동휠체어의 운전 성능 기준을 근거하여 개발 수단의 기기 성능에 대한 요구사항을 정의한다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.601-601
• /
• 2012

본 연구는 Zr이 doping된 ITO target (ITO:Zr)을 $200^{\circ}C$ 이하의 낮은 온도에서 RF magnetron sputtering을 이용한 증착으로 high mobility, high workfunction의 TCO 박막을 제작하고 이를 실리콘 이종접합 태양전지의 front TCO 적용에 관한 연구이다. 상기 공정으로 제작된 ITZO 박막의 가장 낮은 비저항은 $2.58{\times}10-4{\Omega}-cm$이며 이때의 투과도는 90%를 얻을 수 있었다. 또한 기존의 TCO로 사용되던 AZO 및 ITO보다 높은 work function으로 인하여 태양전지의 front TCO 적용시 710 mV 이상의 개방 전압 상승과 band-offset 감소에 따른 34.44 mA 이상의 단락전류 상승을 얻을 수 있었다. 또한 높은 mobility에 의한 면저항 감소로 충진률 상승도 얻을 수 있었다. 상기 인자에 대한 태양전지 특성의 변화는 quantum efficiency 분석으로 규명할 수 있었다.

• Advances in biomechanics and applications
• /
• 제1권1호
• /
• pp.15-22
• /
• 2014

Computed tomography (CT) is being utilized in orthopaedics and related research to estimate bone strength. These applications benefit from calibration of Hounsfield units to mineral density typical of long bone, up to $1750mg/cm^3$. This study describes a method for establishing repeatable calibration of Hounsfield units to density, and determines the effects of imaging medium on calibration accuracy. Four hydroxyapatite standards were imaged in air on 7 occasions over 19 weeks using a helical multi-slice CT scanner. Each standard was scanned 5 times in different media: porcine soft tissue, water, and air. Calibrated densities were highly repeatable (CV<3.5%). No difference in density was observed between water and soft tissue conditions (p>0.08). This work provides a model for determining repeatable scanner-specific density calibration, demonstrates that the linear relationship between Hounsfield units and density extends to values typical of cortical bone, and supports the practice of imaging calibration standards in an environment similar to that of the target bone.

• ETRI Journal
• /
• 제44권3호
• /
• pp.361-378
• /
• 2022

In 5G, the required target for interruption time during a handover (HO) is 0 ms. However, when a handover failure (HOF) occurs, the interruption time increases significantly to more than hundreds of milliseconds. Therefore, to fulfill the requirement in as many scenarios as possible, we need to minimize HOF rate as close to zero as possible. 3GPP has recently introduced conditional HO (CHO) to improve mobility robustness. In this study, we propose "ZEro handover failure with Unforced and automatic time-to-execute Scaling" (ZEUS) algorithm to optimize HO parameters easily in the CHO. Analysis and simulation results demonstrate that ZEUS can achieve a zero HOF rate without increasing the ping-pong rate. These two metrics are typically used to assess an HO algorithm because there is a tradeoff between them. With the introduction of the CHO, which solves the tradeoff, only these two metrics are insufficient anymore. Therefore, to evaluate the optimality of an HO algorithm, we define a new integrated HO performance metric, mobility-aware average effective spectral efficiency (MASE). The simulation results show that ZEUS provides higher MASE than LTE and other CHO variants.

• 한국전기전자재료학회논문지
• /
• 제22권10호
• /
• pp.808-813
• /
• 2009

Indium nitride thin films were deposited by the radio-frequency reactive magnetron sputtering method. The indium target was sputtered by the mixture flow ratio of $N_2$ to Ar, 9:1. The effects of growth temperature on the structural, optical, and electrical properties of the films were investigated. With increasing the growth temperature, the crystallinity of the films was improved, and the crystalline size was increased. The energy bandgap for the film grown at $25^{\circ}C$ was 3.63 eV, and the bandgap showed an increasing tendency on the growth temperature. The carrier concentration, Hall mobility and electrical resistivity of the films depended significantly on the growth temperature and the maximum Hall mobility of $32.3\;cm^2$/Vsec was observed for the film grown at $400^{\circ}C$.

• 한국IT서비스학회지
• /
• 제13권1호
• /
• pp.125-134
• /
• 2014

Device discovery for D2D (device-to-device) communication enables a device to discover other devices in order to initiate communication with them. Devices should perform the discovery phase using a small quantity of radio resource in a short time and be able to reduce the load of the base station. Legacy device discovery schemes have focused on discovering as many target devices as possible. However, it is not appropriate for peer-to-peer D2D communication scenario. Further, synchronization problems are an important issue for discovery signal transmission. This paper proposes a discovery method that one requesting device discovers a specific target for communication. Multiple antenna beamforming is employed for the synchronization between the base station and a target device. The proposal can reduce the load of the base station using the information that it already maintains and improve the reliability of the device discovery because two times of synchronizations using beamforming among the base station and devices can make the exact discovery of a target device with mobility possible.

• 한국전기전자재료학회논문지
• /
• 제30권1호
• /
• pp.23-26
• /
• 2017

Mo doped carbon (C:Mo) thin films were fabricated with various Mo target power densities by unbalanced magnetron sputtering (UBM). The effects of target power density on the surface, structural, and electrical properties of C:Mo films were investigated. UBM sputtered C:Mo thin films exhibited smooth and uniform surfaces. However, the rms surface roughness of C:Mo films were increased with the increase of target power density. Also, the resistivity value of C:Mo film as electrical properties was decreased with the increase of target power density. From the performance of organic thin filml transistor using conductive C:Mo gate electrode, the carrier mobility, threshold voltage, and on/off ratio of drain current (Ion/Ioff) showed $0.16cm^2/V{\cdot}s$, -6.0 V, and $7.7{\times}10^4$, respectively.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제3C권1호
• /
• pp.23-27
• /
• 2003

Structural properties of Cu-Ni alloy films, such as preferred orientation, crystallite size, in-ter-planar spacing, cross-sectional morphology, and electrical resistivity, are investigated in terms of tar-get configurations that are used in the film deposition by means of magnetron co-sputtering. Two different target configurations are considered in this study: a dual-type configuration in which two separate tar-gets (Cu and Ni) and different bias types (RF and DC) are used and a Ni-on-Cu type configuration in which Ni chips are attached to a Cu target. The dual-type configuration appears to have some advantages over the Ni-on-Cu type regarding the accurate control of atomic composition of the deposited Cu-Ni alloy. However, the dual-type-produced film exhibits a porous and columnar structure, the relatively large internal stress, and the high electrical resistivity, which are mainly due to the relatively low mobility of adatoms. The affects of thermal treatment and deposition conditions on the structural and electrical properties of dual-type Cu-Ni films are also discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제6권6호
• /
• pp.1496-1521
• /
• 2012

Uncertainty is ubiquitous in target tracking wireless sensor networks due to environmental noise, randomness of target mobility and other factors. Sensing results are always unreliable. This paper considers unreliability as it occurs in wireless sensor networks and its impact on target-tracking accuracy. Firstly, we map intersection pairwise sensors' uncertain boundaries, which divides the monitor area into faces. Each face has a unique signature vector. For each target localization, a sampling vector is built after multiple grouping samplings determine whether the RSS (Received Signal Strength) for a pairwise nodes' is ordinal or flipped. A Fault-Tolerant Target-Tracking (FTTT) strategy is proposed, which transforms the tracking problem into a vector matching process that increases the tracking flexibility and accuracy while reducing the influence of in-the-filed factors. In addition, a heuristic matching algorithm is introduced to reduce the computational complexity. The fault tolerance of FTTT is also discussed. An extension of FTTT is then proposed by quantifying the pairwise uncertainty to further enhance robustness. Results show FTTT is more flexible, more robust and more accurate than parallel approaches.