• 한국재료학회지
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• 제20권1호
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• pp.25-30
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• 2010

Si nanowire/multiwalled carbon nanotube nanocomposite arrays were synthesized. Vertically aligned Si nanowire arrays were fabricated by Ag nanodendrite-assisted wet chemical etching of n-type wafers using $HF/AgNO_3$ solution. The composite structure was synthesized by formation of a sheath of carbon multilayers on a Si nanowire template surface through a thermal CVD process under various conditions. The results of Raman spectroscopy, scanning electron microscopy, and high resolution transmission electron microcopy demonstrate that the obtained nanocomposite has a Si nanowire core/carbon nanotube shell structure. The remarkable feature of the proposed method is that the vertically aligned Si nanowire was encapsulated with a multiwalled carbon nanotube without metal catalysts, which is important for nanodevice fabrication. It can be expected that the introduction of Si nanowires into multiwalled carbon nanotubes may significantly alter their electronic and mechanical properties, and may even result in some unexpected material properties. The proposed method possesses great potential for fabricating other semiconductor/CNT nanocomposites.

• 구강회복응용과학지
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• 제27권4호
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• pp.405-413
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• 2011

CAD-CAM기법과 CT의 도움으로 무판막임플란트 치료술식이 가능하게 되었다. 본 연구의 목적은 1년간 전향적 연구를 통해 이러한 술식의 신뢰성을 검토하고자 하였다. 하악무치악상태의 연속적인 환자 12명이 포함되었다. 71개의 임플란트가 이공사이에 $NobelGuide^{TM}$법을 이용하여 식립되었고 환자는 정해진 주기에 따라 검사되었다. 한 개의 임플란트가 조기실패하였으며 나머지는 만족할 만한 기능을 보였다. 연구기간 중 평균적인 변연골흡수량은 중앙부($0.3{\pm}0.1$ mm), 견치부($0.5{\pm}0.1$ mm), 원심부($0.7{\pm}0.2$ mm)였으며 임플란트 안정성 수치의 변화량은 중앙부($-1.05{\pm}2.76$ mm), 견치부($-0.85{\pm}2.59$ mm), 원심부($-1.27{\pm}2.18$ mm)를 나타내었고 위치간 통계학적인 차이는 없었다(P>.05). 본 전향적인 기초조사연구에서 CAD-CAM기반의 무판막임플란트 치료술식은 하악무치악환자에게 신뢰성 있는 술식이 될 수 있을 것으로 사료되었다.

• The Journal of Advanced Prosthodontics
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• 제8권3호
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• pp.207-213
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• 2016

PURPOSE. A recently introduced direct drill-guiding implant surgery system features minimal tolerance of surgical instruments in the metal sleeve by using shank-modified drills and a sleeve-incorporated stereolithographic guide template. The purpose of this study was to evaluate the accuracy of this new guided surgery system in partially edentulous patients using geometric analyses. MATERIALS AND METHODS. For the study, 21 implants were placed in 11 consecutive patients using the direct drill-guiding implant surgery system. The stereolithographic surgical guide was fabricated using cone-beam computed tomography, digital scanning, computer-aided design and computer-assisted manufacturing, and additive manufacturing processes. After surgery, the positional and angular deviations between planned and placed implants were measured at the abutment level using implant-planning software. The Kruskal-Wallis test and Mann-Whitney U test were used to compare the deviations (${\alpha}=.05$). RESULTS. The mean horizontal deviations were 0.593 mm (SD 0.238) mesiodistally and 0.691 mm (SD 0.344) buccolingually. The mean vertical deviation was 0.925 mm (SD 0.376) occlusogingivally. The vertical deviation was significantly larger than the horizontal deviation (P=.018). The mean angular deviation was 2.024 degrees (SD 0.942) mesiodistally and 2.390 degrees (SD 1.142) buccolingually. CONCLUSION. The direct drill-guiding implant surgery system demonstrates high accuracy in placing implants. Use of the drill shank as the guiding component is an effective way for reducing tolerance.

• Journal of Periodontal and Implant Science
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• 제44권4호
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• pp.184-193
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• 2014

Purpose: The aim of the present study was to evaluate the in vivo accuracy of flapless, computer-aided implant placement by comparing the three-dimensional (3D) position of planned and placed implants through an analysis of linear and angular deviations. Methods: Implant position was virtually planned using 3D planning software based on the functional and aesthetic requirements of the final restorations. Computer-aided design/computer-assisted manufacture technology was used to transfer the virtual plan to the surgical environment. The 3D position of the planned and placed implants, in terms of the linear deviations of the implant head and apex and the angular deviations of the implant axis, was compared by overlapping the pre- and postoperative computed tomography scans using dedicated software. Results: The comparison of 14 implants showed a mean linear deviation of the implant head of 0.56 mm (standard deviation [SD], 0.23), a mean linear deviation of the implant apex of 0.64 mm (SD, 0.29), and a mean angular deviation of the long axis of $2.42^{\circ}$ (SD, 1.02). Conclusions: In the present study, computer-aided flapless implant surgery seemed to provide several advantages to the clinicians as compared to the standard procedure; however, linear and angular deviations are to be expected. Therefore, accurate presurgical planning taking into account anatomical limitations and prosthetic demands is mandatory to ensure a predictable treatment, without incurring possible intra- and postoperative complications.

• Korean Chemical Engineering Research
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• 제52권2호
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• pp.205-208
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• 2014

본 논문에서는 유기전자소자의 반도체 물질로 많이 사용되는 poly(9,9-dioctylflurorene) (PFO), poly(9,9-dioctylfluorene-co-benthiadiazole) (F8BT), (regioregular poly(3-hexylthiophene) (P3HT)를 기반으로 하는 균일한 크기와 특성을 가지는 고분자 나노와이어를 AAO 템플레이트를 이용하여 대량으로 제작하였다. 제작된 나노와이어는 결점이 없이 깨끗한 표면을 보였으며, 약 250~300 nm의 지름과 ${\sim}30{\mu}m$의 일정한 길이를 가지고 있었다. 나노와이어들은 스프레이 분사 방법을 통하여 유리 기판 위에 균일하게 분사할 수 있었으며, PFO와 F8BT 나노와이어의 경우 UV 빛의 조사하에 각각 나노와이어의 전체에 걸쳐서 왜곡없이 밝은 yellow와 blue luminescence를 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권9호
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• pp.4491-4509
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• 2017

The present paper proposes a novel dynamic system for hand gesture recognition. The approach involved is comprised of three main steps: detection, tracking and recognition. First, the gesture contour captured by a 2D-camera is detected by combining the three-frame difference method and skin-color elliptic boundary model. Then, the trajectory of the hand gesture is extracted via a gesture-tracking algorithm based on an occlusion-direction oriented linear extrapolation predictor, where the gesture coordinate in next frame is predicted by the judgment of current occlusion direction. Finally, to overcome the interference of insignificant trajectory segments, the longest common subsequence (LCS) is employed with the aid of velocity information. Besides, to tackle the subgesture problem, i.e., some gestures may also be a part of others, the most probable gesture category is identified through comparison of the relative LCS length of each gesture, i.e., the proportion between the LCS length and the total length of each template, rather than the length of LCS for each gesture. The gesture dataset for system performance test contains digits ranged from 0 to 9, and experimental results demonstrate the robustness and effectiveness of the proposed approach.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.282-283
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• 2005

Ion beam assisted deposition(IBAD) technique was used to produce biaxially textured polycrystalline MgO thin films for high critical current YBCO coated conductor. Hastelloy tapes were continuous electropolished with very smooth surface for IBAD-MgO deposition, RMS roughness of Hastelloy tape values below 2 nm and local slope of less than $1^{\circ}$. After the polishing of the tape an amorphous $Y_2O_3$ and $Al_2O_3$ are deposited Biaxially textured MgO was deposited on amorphous layer bye-beam evaporation with a simultaneous bombardment of high energy ions. We had developed the RHEED to measure in-situ biaxial texture of film surface as thin as tens angstrom. And also ex-situ characterization of buffer layers was studied using XRD and SEM. The full-width at half maximum(FWHM) out of plane texture of IBAD-MgO template is $4^{\circ}$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.252.2-252.2
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• 2013

ZnO nanostructures have a lot of interest for decades due to its varied applications such as light-emitting devices, power generators, solar cells, and sensing devices etc. To get the high performance of these devices, the factors of nanostructure geometry, spacing, and alignment are important. So, Patterning of vertically- aligned ZnO nanowires are currently attractive. However, many of ZnO nanowire or nanorod fabrication methods are needs high temperature, such vapor phase transport process, metal-organic chemical vapor deposition (MOCVD), metal-organic vapor phase epitaxy, thermal evaporation, pulse laser deposition and thermal chemical vapor deposition. While hydrothermal process has great advantages-low temperature (less than $100^{\circ}C$), simple steps, short time consuming, without catalyst, and relatively ease to control than as mentioned various methods. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using of nanosphere template with various precursor concentration and components via hydrothermal process. The brief experimental scheme is as follow. First synthesized ZnO seed solution was spun coated on to cleaned Si substrate, and then annealed $350^{\circ}C$ for 1h in the furnace. Second, 200nm sized close-packed nanospheres were formed on the seed layer-coated substrate by using of gas-liquid-solid interfacial self-assembly method and drying in vaccum desicator for about a day to enhance the adhesion between seed layer and nanospheres. After that, zinc oxide nanowires were synthesized using a low temperature hydrothermal method based on alkali solution. The specimens were immersed upside down in the autoclave bath to prevent some precipitates which formed and covered on the surface. The hydrothermal conditions such as growth temperature, growth time, solution concentration, and additives are variously performed to optimize the morphologies of nanowire. To characterize the crystal structure of seed layer and nanowires, morphology, and optical properties, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) studies were investigated.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2384-2393
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• 2018

Porous alginate-based hydrogel beads (porous ABH) have been prepared through a facile and sustainable template-assisted method using nano-calcium carbonate and nano-$CaCO_3$ as pore-directing agent for the efficient capture of methylene blue (MB). The materials were characterized by various techniques. The sorption capacities of ABH towards MB were compared with pure sodium alginate (ABH-1:0) in batch and fixed-bed column adsorption studies. The obtained adsorbent (ABH-1:3) has a higher BET surface area and a smaller average pore diameter. The maximum adsorption capacity of ABH-1:3 obtained from Langmuir model was as high as $1,426.0mg\;g^{-1}$. The kinetics strictly followed pseudo-second order rate equation and the adsorption reaction was effectively facilitated, approximately 50 minutes to achieve adsorption equilibrium, which was significantly shorter than that of ABH-1:0. The thermodynamic parameters revealed that the adsorption was spontaneous and exothermic. Thomas model fitted well with the breakthrough curves and could describe the dynamic behavior of the column. More significantly, the uptake capacity of ABH-1:3 was still higher than 75% of the maximum adsorption capacity even after ten cycles, indicating that this novel adsorbent can be a promising adsorptive material for removal of MB from aqueous solution under batch and continuous systems.

• 멤브레인
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• 제29권3호
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• pp.183-189
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• 2019

양친성 PCZ-r-PEG 랜덤 공중합체를 기반으로 한 수열합성법을 통해 자가조립된 메조기공 이산화티타늄 마이크로 스피어를 합성하였다. 중합된 PCZ-r-PEG는 푸리에 변환 적외분광법(fourier transform infrared spectroscopy, FT-IR), 핵자기공명(nuclear magnetic resonance, NMR), 젤 투과 크로마토그래피(gel permeation chromatography, GPC) 그리고 투과전자 현미경(transmission electron microscopy, TEM)을 통해 그 특성이 분석되었다. 다공성 이산화티타늄 입자는 PCZ-r-PEG, 글루코스(glucose), 물을 테트라히드로푸란(tetrahydrofuran, THF) 용액에 분산시킨 뒤 $150^{\circ}C$, 12시간 동안 반응시켰다. 다공성 이산화티타늄 입자의 구조와 결정성 분석을 위해 주사전자현미경(scanning electron microscopy, SEM)과 엑스선 회절(X-ray diffraction, XRD)이 사용되었다.