• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.188-193
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• 2011

The osseointegration of dental implant is influenced by many factors such as surface geometry, loading and the amount of bone. Thus, stability of the dental implant should be checked periodically. In order to test the stability of dental implant by using resonance frequency analysis, we designed a structure of transducers and fabricated a piezoelectric devices. Using finite element analysis, the thickness and length of piezoelectric device and transducers were tailorized and the optimized frequency of 10 kHz was obtained. The resonance frequency from simulation analysis and evaluation was estimated to be similar as 10 kHz. The osseointegration was further enhanced with increasing frequency from the evaluation result of the finite element analysis.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.821-825
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• 2009

Recently, transparent ZnO-based TFTs have attracted much attention for flexible displays because they can be fabricated on plastic substrates at low temperature. We report the fabrication and characteristics of ZnO TFTs having different channel thicknesses deposited at low temperature. The ZnO films were deposited as active channel layer on $Si_3N_4/Ti/SiO_2/p-Si$ substrates by RF magnetron sputtering at $100^{\circ}C$ without additional annealing. Also, the ZnO thin films deposited at oxygen partial pressures of 40%. ZnO TFTs using a bottom-gate configuration were investigated. The $Si_3N_4$ film was deposited as gate insulator by PE-CVD at $150^{\circ}C$. All Processes were processed below $150^{\circ}C$ which is optimal temperature for flexible display and were used dry etching method. The fabricated devices have different threshold slop, field effect mobility and subthreshold slop according to channel thickness. This characteristics are related with ZnO crystal properties analyzed with XRD and SPM. Electrical characteristics of 60 nm ZnO TFT (W/L = $20\;{\mu}m/20\;{\mu}m$) exhibited a field-effect mobility of $0.26\;cm^2/Vs$, a threshold voltage of 8.3 V, a subthreshold slop of 2.2 V/decade, and a $I_{ON/OFF}$ ratio of $7.5\times10^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.65-65
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• 2007

Microstructure and surface roughness of the sensing materials should be improved to use them in advanced sensor applications because the uneven surface roughness degrades the light reflection, pattern resolution, and devices performance. Chemical mechanical polishing (CMP) processing was selected for improving the surface roughness of $CeO_2$ which is one of the well known materials for the oxygen gas sensors. Surface roughness and removal rate of spin coated $CeO_2$ thin films were examined with a change of CMP process parameters such as down force and table speed. The optimized process condition, reflected by the surface roughness with the hillock-free surface as well as the excellent removal rate with the good uniformity, was obtained. The effects of the improved surface roughness on the sensing property of $CeO_2$ thin films were also confirmed. The improved sensitivity of $CeO_2$ thin films for oxygen sensors were obtained after CMP process by the improved surface characteristics. Therefore, we conclude that sensing property of $CeO_2$ thin film is strongly dependent on the surface roughness of $CeO_2$ thin films by using CMP process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.533-533
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• 2007

The stress effect of SiGe p-type metal oxide semiconductors field effect transistors(MOSFETs) has been investigated to compare device properties using Si bulk and partially depleted silicon on insulator(PD SOI). The electrical properties in SiGe PD SOI presented enhancements in subthreshold slope and drain induced barrier lowering in comparison to SiGe bulk. The reliability of gate oxides on bulk Si and PD SOI has been evaluated using constant voltage stressing to investigate their breakdown (~ 8.5 V) characteristics. Gate leakage was monitored as a function of voltage stressing time to understand the breakdown phenomena for both structures. Stress induced leakage currents are obtained from I-V measurements at specified stress intervals. The 1/f noise was observed to follow the typical $1/f^{\gamma}$ (${\gamma}\;=\;1$) in SiGe bulk devices, but the abnormal behavior ${\gamma}\;=\;2$ in SiGe PD SOI. The difference of noise frequency exponent is mainly attributed to traps at silicon oxide interfaces. We will discuss stress induced instability in conjunction with the 1/f noise characteristics in detail.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.691-697
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• 2000

$Al_xGa_{1-x}N$ thin layers are promising materials for optical devices in the UV regions. $Al_xGa_{1-x}N$ thin layers w were grown on sapphire substrates by metalorgaruc chemical vapor deposition (MOCVD). The molar Al fraction and crystallinity of layers were deduced from synchrotron x-ray scattering experiment. Surface morphology were investigated using SEM and SPM. $Al_xGa_{1-x}N$ layers crystallinity were related with undoped GaN crystallinity. The Al mole fraction of $Al_xGa_{1-x}N$ layers affect the surface morphology of $Al_xGa_{1-x}N$ layers. The surface morphology was rough­e ened and the cracks were obse$\pi$ed by increasing the Al mole fractions.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.9
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• pp.285-292
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• 2016

By adding short-range wireless communication function such as Bluetooth and Wi-Fi to the last vehicle in conjunction with a smart phone, a modern automobile is becoming entertainment screen to determine a variety of information such as car location information, diagnosis information, etc. through the ECU vehicle electronic control unit. In this study, by utilizing short-range communications capability of the on-board diagnostic devices and smart phones in association with the on-board diagnostics, compatibility tests among a number of smart phone models, Bluetooth and NFC(Near Field Communication) were carried out and those results were analyzed. Furthermore, composition of on-board diagnostic device having Bluetooth and NFC interface function and the fault diagnosis function were implemented, and fault diagnosis debugging program was developed. In addition, fault diagnosis data of the vehicle via the OBD-II interface was extracted. Finally, the on-board diagnostics CAN Protocol implementation has been proposed, and the results of work was analyzed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.255-255
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• 2010

Recently, nonvolatile memories (NVM) of various types have been researched to improve the electrical performance such as program/erase voltages, speed and retention times. Also, the charge trap memory is a strong candidate to realize the ultra dense 20-nm scale NVM. Furthermore, the high charge efficiency and the thermal stability of SiC nanocrystals NVM with single $SiO_2$ tunnel barrier have been reported. [1-2] In this study, the SiC charge trap NVM was fabricated and electrical properties were characterized. The 100-nm thick Poly-Si layer was deposited to confined source/drain region by using low-pressure chemical vapor deposition (LP-CVD). After etching and lithography process for fabricate the gate region, the $Si_3N_4/SiO_2/Si_3N_4$ (NON) and $SiO_2/Si_3N_4/SiO_2$ (ONO) barrier engineered tunnel layer were deposited by using LP-CVD. The equivalent oxide thickness of NON and ONO tunnel layer are 5.2 nm and 5.6 nm, respectively. By using ultra-high vacuum magnetron sputtering with base pressure 3x10-10 Torr, the 2-nm SiC and 20-nm $SiO_2$ were successively deposited on ONO and NON tunnel layers. Finally, after deposited 200-nm thick Al layer, the source, drain and gate areas were defined by using reactive-ion etching and photolithography. The lengths of squire gate are $2\;{\mu}m$, $5\;{\mu}m$ and $10\;{\mu}m$. The electrical properties of devices were measured by using a HP 4156A precision semiconductor parameter analyzer, E4980A LCR capacitor meter and an Agilent 81104A pulse pattern generator system. The electrical characteristics such as the memory effect, program/erase speeds, operation voltages, and retention time of SiC charge trap memory device with barrier engineered tunnel layer will be discussed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2127-2134
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• 2007

The electronic learning helped a learner to overcome the time restriction by providing mobility, instantly and flexibility but the restriction in connection with space on cable computer remained unsolved. Accordingly, the electronic learning has tendency to change into mobile learning environment which allows a learner to overcome time and spatial restriction. However, these mobile devices have a limitation to awareness of learning contents provided over the realtime video movie due to its small display size. Therefore, this paper suggests a technique according to the following priority: for a real time learning image, extract region of study for region of interest, rescale the real time image to its proper size suitable for the display device, and then make it displayed on a wireless PDA. As a result of the experiment, we reduced the calculating time by sampling the field centering on learning contents adaptively and computing the field best suited for device size of the user effectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.437-443
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• 2019

All-solid-state thin-film lithium-ion batteries are important in the development of next-generation energy storage devices with high energy density. However, thin-film batteries have many challenges in their manufacturing procedure. This is because there are many factors, such as substrate selection, to consider when producing the thin film multilayer structure. In this study, we compare the fabrication and performance of all-solid-state thin-film lithium-ion batteries with a $LiNi_{0.5}Mn_{1.5}O_4$ cathode/LiPON solid electrolyte/$Li_4Ti_5O_{12}$ anode structure using stainless steel and Si substrates with different surface roughness. We demonstrate that the smoother the surface of the substrate, the thinner the thickness of the all-solid-state thin-film lithium-ion battery that can be made, and as a result, the corresponding electrochemical characteristics can be improved.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.5
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• pp.977-984
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• 2019

This paper proposes a single image dehazing that utilizes the transmission estimation with low complexity and the pixel-based JBDCP (Joint Bright and Dark Channel Prior) for the effective application of hazy outdoor images. The conventional transmission estimation includes the refinement process with high computational complexity and memory requirements. We propose the transmission estimation using combination of pixel- and block-based dark channel information and it significantly reduces the complexity while preserving the edge information accurately. Moreover, it is possible to estimate the transmission reflecting the image characteristics, by obtaining a different air-light for each pixel position of the image using the pixel-based JBDCP. Experimental results on various hazy images illustrate that the proposed method exhibits excellent dehazing performance with low complexity compared to the conventional methods; thus, it can be applied in various fields including real-time devices.