• Journal of Periodontal and Implant Science
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• v.45 no.2
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• pp.38-45
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• 2015

Purpose: The purpose of this study was to evaluate the effect of photodynamic therapy (PDT) using erythrosine and a green light emitting diode (LED) light source on biofilms of Aggregatibacter actinomycetemcomitans attached to resorbable blasted media (RBM) and sandblasted, large-grit, acid-etched (SLA) titanium surfaces in vitro. Methods: RBM and SLA disks were subdivided into four groups, including one control group and three test groups (referred to as E0, E30, E60), in order to evaluate the effect of PDT on each surface. The E0 group was put into $500{\mu}L$ of $20{\mu}M$ erythrosine for 60 seconds without irradiation, the E30 group was put into erythrosine for 60 seconds and was then irradiated with a LED for 30 seconds, and the E60 group was put into erythrosine for 60 seconds and then irradiated with a LED for 60 seconds. After PDT, sonication was performed in order to detach the bacteria, the plates were incubated under anaerobic conditions on brucella blood agar plates for 72 hours at $37^{\circ}C$, and the number of colony-forming units (CFUs) was determined. Results: Significant differences were found between the control group and the E30 and E60 groups (P<0.05). A significantly lower quantity of CFU/mL was found in the E30 and E60 groups on both titanium disk surfaces. In confocal scanning laser microscopy images, increased bacterial death was observed when disks were irradiated for a longer period of time. Conclusions: These findings suggest that PDT using erythrosine and a green LED is effective in reducing the viability of A. actinomycetemcomitans attached to surface-modified titanium in vitro.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.3
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• pp.420-427
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• 2015

It is necessary to understand the cellular uptake and cytotoxicity of food-grade delivery systems, such as ${\beta}$-lactoglobulin (${\beta}$-lg) nanoparticles, for the application of bioactive compounds to functional foods. The objectives of this study were to investigate the relationships between the physicochemical properties of ${\beta}$-lg nanoparticles, such as particle size and zeta-potential value, and their cellular uptakes and cytotoxicity in Caco-2 cells. Physicochemical properties of ${\beta}$-lg nanoparticles were evaluated using particle size analyzer. Flow cytometry and confocal laser scanning microscopy were used to investigate cellular uptake and cytotoxicity of ${\beta}$-lg nanoparticles. The ${\beta}$-lg nanoparticles with various particle sizes (98 to 192 nm) and zeta-potential values (-14.8 to -17.6 mV) were successfully formed. A decrease in heating temperature from $70^{\circ}C$ to $60^{\circ}C$ resulted in a decrease in the particle size and an increase in the zeta-potential value of ${\beta}$-lg nanoparticles. Non-cytotoxicity was observed in Caco-2 cells treated with ${\beta}$-lg nanoparticles. There was an increase in cellular uptake of ${\beta}$-lg nanoparticles with a decrease in particle size and an increase in zeta-potential value. Cellular uptake ${\beta}$-lg nanoparticles was negatively correlated with particle size and positively correlated with zeta-potential value. Therefore, these results suggest that the particle size and zeta-potential value of ${\beta}$-lg nanoparticles play an important role in the cellular uptake. The ${\beta}$-lg nanoparticles can be used as a delivery system in foods due to its high cellular uptake and non-cytotoxicity.

• Journal of Broadcast Engineering
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• v.21 no.1
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• pp.3-10
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• 2016

In this paper, two reconstructed point cloud sets with the information of 3D features are analyzed. For a certain 3D reconstruction of the interior of a building, the first image set is taken from the sequential passive camera movement along the regular grid path and the second set is from the application of the laser scanning process. Matched key points over all images are obtained by the SIFT(Scale Invariant Feature Transformation) algorithm and are used for the registration of the point cloud data. The obtained results are point cloud number, average density of point cloud and the generating time for point cloud. Experimental results show the necessity of images from the additional sensors as well as the images from the camera for the more accurate 3D reconstruction of the interior of a building.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.185-185
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• 2016

아크릴계 수지(resin)에 인조 흑연과 탄소나노튜브(carbon nanotube)를 1:1 비율로 혼합한 충전제(filler)와 용제(solvent) 및 기타 첨가제(additives)를 혼합하여 방열도료를 제조하여 수직방향 열전도도를 상온에서 평가하였다. 충전제의 함량을 1, 2, 5 중량 %로 변화시키며 원료들을 준비하여 교반기로 혼합한 뒤 3단 롤 밀(three roll mill)로 분산공정을 진행하여 3 종류의 도료를 제조하였다. 제조한 도료를 가로 11 mm, 세로 11 mm, 두께 0.4 mm의 Al 5052 알루미늄 기판에 스프레이 코팅 방식으로 도포한 후 $150^{\circ}C$에서 30분 동안 열경화 건조 과정을 거쳐 샘플을 제작하였다. 측정 시료의 형상은 대략적으로 Fig. 1과 같다. 열전도도는 식 $k={\alpha}{\cdot}C_p{\cdot}{\rho}$를 사용해서 계산된다. 여기서 k는 열전도도($W/m{\cdot}K$), ${\alpha}$는 열확산계수($mm^2/s$), $C_p$는 비열($J/kg{\cdot}K$), ${\rho}$는 밀도($g/cm^3$)를 나타낸다. 열확산계수는 독일 NETZSCH 사의 Laser Flash Analysis 장비(모델명 LFA 457)를 사용하여 측정하였는데, 기판 뒤쪽에서 레이저를 조사하고 도료층 전면에서 적외선 온도센서를 통해 시간에 따른 온도 상승곡선을 구한 후, 두 물체의 계면에서의 접촉 열저항(contact thermal resistance)을 감안하여 장비에 내장되어 있는 소프트웨어로 열확산계수가 계산된다. 비열은 같은 회사의 DSC(Differential Scanning Calorimetry) 200 F3 장비를 사용해 측정했으며, 밀도는 부피와 질량을 측정한 값을 이용하여 계산하였다. 도료를 도포하지 않은 bare Al plate에 대해서는 쉽게 열확산계수, 비열, 밀도를 측정하여 열전도도를 구할 수 있다. 도료가 코팅된 샘플에 대해서는 도료층을 일부 떼어내 비열을 측정하고, 밀도를 구한 후, 도료층의 열전도도가 2-layer 법으로 장비 내장 소프트웨어로 계산된다, 이때 Al 기판의 열확산계수, 비열, 밀도는 미리 측정한 bare Al plate의 값을 적용하였다. 실험 결과를 Table 1에 정리하였다. 흑연과 탄소나노튜브를 혼합한 충전제를 함유한 아크릴 복합체 박막에서 측정된 열전도도는 보통 고분자 재료의 열전도도 값의 상한 영역에 육박하는 값이며, 충전제 함량이 증가할수록 열전도도가 증가하는 경향을 보이고 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1214-1218
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• 2005

As demands for precision parts are increased, existing methods to fabricate them such as MEMS, LIGA technology have the technical limitations like high precision, high functionality and ultra miniaturization. A micro-stereolithography technology based on $DMD^{TM}$(Digital Micromirror Device) can meet these demands. In this technology, STL file is the standard format as the same of conventional rapid prototyping system, and 3D part is fabricated by stacking layers that are sliced as 2D section from STL file. Whereas in conventional method, the resin surface is cured as scanning laser beam spot according to the section shape, but in this research, we use integral process which enables to cure the resin surface at one time. In this paper, we deal with the dynamic pattern generation and $DMD^{TM}$ operation to fabricate micro structures. Firstly, we address effective slicing method of STL file, conversion to bitmap, and dynamic pattern generation. Secondly, we suggest $DMD^{TM}$ operation and optimal support manufacturing for $DMD^{TM}$ mounting. Thirdly, we examine the problems on continuous stacking layers, and their improvements in software aspects.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.3
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• pp.23-32
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• 2005

A change of z-directional structural and surface properties by calendering has a great influence on liquid penetration into a sheet. It could be also important for multi-ply sheet because it contacts liquid dunhg coating or converting process. Therefore, this study was aimed to evaluate of a change of z-directional structure in multi-ply sheet by calendering. To do this, multi-ply sheets were prepared with various raw materials and calendered at the different pressure and temperature conditions. In multi-ply sheet which consisted of one kind of pulp fiber, thickness reductions were higher in top and bottom plies than in middle plies. And in the case of soft nip calender treatment with high temperature, top layer which was in contact with heating roll showed the highest reduction of thickness. Hard nip calender treatment showed U-shaped density profile in z-direction, but compression profile by SNC treatment was dependent on calendering condition. To examine z-directional structure of multi-ply sheet which was composed of different raw material for each layer, CLSM (Confocal Laser Scanning Microscopy) analyses were carried out on cross direction of sheet. It turned out to be a useful tool for investigating z-directional analysis. As a result, variation of thickness reduction in z-direction is dependent on ply structure, compressibility of pulp fiber, and calendering condition.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.49-55
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• 2013

To explore the paper materials for restoration of the Annals of the Joseon Dyansty, durability of the three type of the traditional Korean Papers were estimated in this study, through moist heat artificial aging test. Three types(D, F, and G) which showed the best preservation performance in dry heat and UV treatment in the previous study were selected and artificial accelerated aging treatment with moist-heat process was conducted; the viscosity change rate was D>G>F; folding endurance G>D>F; $L^*$ value F>D>G; $a^*$ and $b^*$ change rate D>G>F; brightness decrease rate D>G>F, suggesting paper F showed the least change rate in physical/optical properties. Also the CLSM image observation showed fair coherence among fibers and confirmed paper mulberry. And in FDI extraction from each sample, paper F showed the highest value. Overall, paper F (traditional glossy paper) showed the highest stability against thermal treatment. It confirms that paper F is suitable as restoration paper for tributary remains including the annals of the Joseon Dynasty for its steady strength/viscosity decrease rate and color change rate.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.35.1-35.1
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• 2011

New photovoltaic (PV) materials and manufacturing approaches are needed for meeting the demand for lower-cost solar cells. The prototypal thin-film photovoltaic absorbers (CdTe and $Cu(In,Ga)Se_2$) can achieve solar conversion efficiencies of up to 20% and are now commercially available, but the presence of toxic (Cd,Se) and expensive elemental components (In, Te) is a real issue as the demand for photovoltaics rapidly increases. To overcome these limitations, there has been substantial interest in developing viable alternative materials, such as $Cu_2ZnSnS_4$ (CZTS) is an emerging solar absorber that is structurally similar to CIGS, but contains only earth abundant, non-toxic elements and has a near optimal direct band gap energy of 1.4~1.6 ev and a large absorption coefficient of ${\sim}10^4\;cm^{-1}$. The CZTS absorber layers are grown and investigated by various fabrication methods, such as thermal evaporation, e-beam evaporation with a post sulfurization, sputtering, non-vacuum sol-gel, pulsed laser, spray-pyrolysis method and electrodeposition technique. In the present work, we report an alternative method for large area deposition of CZTS thin films that is potentially high throughput and inexpensive when used to produce monolithically integrated solar panel modules. Specifically, we have developed an aqueous chemical approach based on chemical bath deposition (CBD) with a subsequent sulfurization heat treatment. Samples produced by our method were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, absorbance and photoluminescence. The results show that this inexpensive and relatively benign process produces thin films of CZTS exhibiting uniform composition, kesterite crystal structure, and good optical properties. A preliminary solar cell device was fabricated to demonstrate rectifying and photovoltaic behavior.

• Journal of KIISE
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• v.44 no.4
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• pp.392-398
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• 2017

The point-cloud representation of an object is performed by scanning a space through a laser scanner that is extracting a set of points, and the points are then integrated into the same coordinate system through a registration. The set of the completed registration-integrated point clouds is classified into meaningful regions, shapes, and noises through a mathematical analysis. In this paper, the aim is the matching of a curved area like a cylinder shape in 3D point-cloud data. The matching procedure is the attainment of the center and radius data through the extraction of the cylinder-shape candidates from the sphere that is fitted through the RANdom Sample Consensus (RANSAC) in the point cloud, and completion requires the matching of the curved region with the Catmull-Rom spline from the extracted center-point data using the Principal Component Analysis (PCA). Not only is the proposed method expected to derive a fast estimation result via linear and curved cylinder estimations after a center-axis estimation without constraint and segmentation, but it should also increase the work efficiency of reverse engineering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.568-573
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• 2011

AZO (Al doped ZnO) thin films were deposited on the quartz substrates with thickness variation from 25 to 300 nm by using PLD (pulsed laser deposition). XRD (x-ray diffractometer), SPM (scanning probe microscopy), Hall effect measurement and uv-visible spectrophotometer were employed to investigate the structural, morphological, electrical and optical properties of the thin films. XRD results demonstrated that films were preferrentially oriented along the c-axis and crystallinity of film was improved with increase of film thickness. As for the surface morphologies, the mean diameter and root mean square of grains were increased as the film thickness was increased. When the film thickness was 200 nm, the lowest resistivity of $4.25{\times}10^{-4}\;{\Omega}cm$ obtained with carrier concentration of $6.84{\times}10^{20}\;cm^{-3}$ and mobility of $21.4\;cm^2/V{\cdot}S$. All samples showed more than 80% of transmittance in the visible range. Upon these results, it is found that the samples thickness can affect their structural, morphological, optical and electrical properties. This study suggests that the resistivity can be improved by controlling film thickness.