• Title/Summary/Keyword: deposition pattern

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Investigation of the interface between diamond film and silicon substrate using transmission electron microscopy (투과 전자 현미경을 이용한 다이아몬드 박막과 실리콘 기판의 계면 연구)

  • 김성훈
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.10 no.2
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    • pp.100-104
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    • 2000
  • Diamond film was deposited on Si substrate by using microwave plasma-enhanced chemical vapor deposition (MPECVD) system. After thinning the cross section between diamond film and Si substrate by ion milling method, we investigated its interface via transmission electron microscopy We could observe that the diamond film was grown either directly on Si substrate or via the interlayer between diamond film and Si substrate. Thickness of the interlayer was varied along the cross section. The interlayer might mainly composed of Sic andlor amorphous carbon. We could observe the well-developed electron diffraction pattern of both Si and diamond around the interface. Based on this result, we can conjecture the initial growth behavior of diamond film on Si substrate.

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A Prediction Model of Transverse Bed Slope in Meandering Rivers (사행하천(蛇行河川)의 횡방향(橫方向) 하상경사(河床傾斜)의 예측모형(豫測模型))

  • Hong, Chang Sun;Chung, Yong Tai
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.11 no.4
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    • pp.81-89
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    • 1991
  • An interesting property of meandering river patterns is that they slowly deform, as bank erosion on one side of a channel and deposition on the other side result in the location of the channel. In this study we used a sine-generated meander pattern proposed by Langbein and Leopold(1966) to develop a solution of a linear, second-order differential equation of transverse bed slope(bed topography) proposed by Odgaard(1986). A new model for transverse bed slope(bed topography), that accounts for the phase lag and the influence of the width to depth aspect ratio, was developed in this study and compared with results of field measurements.

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Spray Deposit Distribution of a Small Orchard Sprayer (소형 과수방제기 살포입자의 부착량 분포)

  • Koo, Young-Mo
    • Journal of Biosystems Engineering
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    • v.32 no.3
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    • pp.145-152
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    • 2007
  • Uniformity of spray deposit is one of the important factors in spray performance affecting efficacy of pest management. Distributions of spray deposit on artificial targets were measured and analyzed to enhance the efficiency of spray application. The research was studied to understand the deposition characteristics of spray droplets and to determine the optimum conditions of chemical application. The deposit and its pattern by the lower fan speed was more uniform and higher than that by the higher fan speed. The upward blasting distance was limited within 3 m, but the limit to the ground level was expanded the distance more than 3.5 m because of the accumulated droplets. When the fan speed was higher at the distance of 2.5 m, deposit reached to maximum. When the distance increased, deposit was getting lower. At the both fan speeds, the deposit was concentrated below $30^{\circ}$ because of the gravitation and the resistance of wind. This research can be useful in designing an orchard sprayer and its operation for various tree canopies. To achieve a uniform distribution of deposit using the air-blast type orchard sprayer, the application rate from the middle boom should be increased as the air velocity to the upward increased. The spray rate to the side boom should be limited in a minimal level.

Analysis the depth effect of organic pollutants and heavy metals using biostimulant ball in contaminated coastal sediments (해양오염저질의 오염물질 정화를 위한 생물활성촉진제 투여 깊이 연구)

  • Song, Young-chae;Woo, Jung-Hui;Subha, Bakthavachallam
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • 2015.07a
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    • pp.177-178
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    • 2015
  • Sediments play a major role in determining pollution pattern in aquatic systems and reflecting the pollutant deposition. In the present study analysis the depth effect of organic pollutants and heavy metals using slow release biostimulant ball (BSB) in coastal sediment. BSB size fixed at 3cm, depth varied from 0cm to 10cm depth and 1 and 3 month interval period was carried out for the study. The organic pollutants of chemical oxygen demand, total solids and volatile solids were significantly changed at the surface sediment (0cm)in 1 month and 3 month interval time using BSB. In contrast, sediment depth increase upto 10cm the reduction percentage decrease like to control. Vertical distribution of heavy metals are not consistent from the surface layer toward the bottom layers. Heavy metals fractions were significantly changes, the exchangeable fraction was reduced and other organic and residual fractions were stabilized percentage are increased. This finding concluded BSB is effective for reduce organic pollutants, heavy metals stabilization from the contaminated sediment.

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Changes of Sedimentary Environments in the Southern Tidal Flat of Kanghwa Island (강화 남부 갯벌의 퇴적환경 변화)

  • Woo, Han-Jun;Je, Jong-Geel
    • Ocean and Polar Research
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    • v.24 no.4
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    • pp.331-343
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    • 2002
  • The southern tidal flat of Kanghwa Island with an area of approximately $90km^2$ is one of the biggest flats on the west coast of Korea. Surface sediments for sedimentary analyses were sampled at 83 stations in August 1997, September 1999 and August 2000. The very poorly-sorted mud sediments were predominant in the eastern part of the tidal flat, whereas the poorly-sorted sand-mud mixed sediments were dominant in the western part. The area of muddy sediment distribution diminished, but that of sandy mud sediment extended to southeastward tidal flat for three years. In the western part of tidal flat, deposition occurred during the period of spring to summer, whereas erosion occurred in winter. Sediment accumulation rates during three years indicated that the sediments deposited continuously in the eastern part of tidal flat, whereas eroded in the western part of tidal flat. Recently, construction of artificial structures such as new airport, island-connecting bridges and dikes near the tidal flat might change tidal current and river flow pattern. In order to reduce the ecological damage and to preserve tidal-flat environment, it is necessary to Investigate long-term impacts on sedimentary environment and ecology.

Numerical Analysis on the Flow Characteristics Considering the Inspiratory Flow Rate in a Human Airway (수치해석 기법을 이용한 호흡 유량에 따른 사람의 기도 내 유동 특성 연구)

  • Sung, Kun Hyuk;Ryou, Hong Sun
    • Journal of Biomedical Engineering Research
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    • v.33 no.4
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    • pp.177-183
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    • 2012
  • The inspiratory flow rate of a human is changed with the amount of the workload. The flow characteristic is affected by the inspiratory flow rate. In the flow field of airway, the both of turbulence intensity and secondary flow affect the deposition pattern of particles which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The relatively inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. The low Reynolds number k-${\omega}$ turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the turbulence kinetic energy and secondary flow intensity increase in airway. On the other hand, the area of recirculation zone is smaller.

Metal Surface Treatment Effects on Screen Printed Silicon Solar Cells

  • Chakrabarty K.;Mangalaraj D.;Kim K. H.;Dhungel S. K.;Park J. H.;Singh S. N.
    • Transactions on Electrical and Electronic Materials
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    • v.4 no.4
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    • pp.22-25
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    • 2003
  • High series resistance due to the presence of glass frit is one of the major problems for screen printed silicon solar cells. Cells having electrical parameters below the prescribed values are usually rejected during solar module fabrication. Therefore, it is highly desirable to improve the electrical parameters of the silicon solar cells and thereby to increase the overall production yield. It was observed that, the performance of low quality mono-crystalline silicon solar cells made by standard screen printing technology could be improved remarkably by novel surface treatment. We have chemically treated the surface using sodium hydroxide (NaOH) and silver nitrate ($AgNO_3$) solutions. NaOH treatment helps to reduce the series resistance by decreasing the presence of excess glass frit on the top silver grid contact. The $AgNO_3$ treatment is used to reduce the series resistance comes from the deposition of silver on the grids by filling the holes present (if any) within the grid pattern.

Properties of Aluminum Doped Zinc Oxide Thin Film Prepared by Sol-gel Process

  • Yi, Sung-Hak;Kim, Jin-Yeol;Jung, Woo-Gwang
    • Korean Journal of Materials Research
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    • v.20 no.7
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    • pp.351-355
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    • 2010
  • Transparent conducting aluminum-doped ZnO thin films were deposited using a sol-gel process. In this study, the important deposition parameters were investigated thoroughly to determine the appropriate procedures to grow large area thin films with low resistivity and high transparency at low cost for device applications. The doping concentration of aluminum was adjusted in a range from 1 to 4 mol% by controlling the precursor concentration. The annealing temperatures for the pre-heat treatment and post-heat treatment was $250^{\circ}C$ and 400-$600^{\circ}C$, respectively. The SEM images show that Al doped and undoped ZnO films were quite uniform and compact. The XRD pattern shows that the Al doped ZnO film has poorer crystallinity than the undoped films. The crystal quality of Al doped ZnO films was improved with an increase of the annealing temperature to $600^{\circ}C$. Although the structure of the aluminum doped ZnO films did not have a preferred orientation along the (002) plane, these films had high transmittance (> 87%) in the visible region. The absorption edge was observed at approximately 370 nm, and the absorption wavelength showed a blue-shift with increasing doping concentration. The ZnO films annealed at $500^{\circ}C$ showed the lowest resistivity at 1 mol% Al doping.

Histopathologic Lesion of Mannheimia haemolytica pneumonia in calves (송아지에서 발생한 Mannheimia haemolytica 폐렴의 병리조직학적 소견)

  • Jean, Young Hwa;Roh, In Soon;Lee, Kyung Hyun;Lee, Kyung Woo;Lee, Hee Soo
    • Korean Journal of Veterinary Research
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    • v.48 no.3
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    • pp.317-321
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    • 2008
  • Four 5 month old calves were died after showing respiratory distress after long-distance transportation at winter season. They were diagnosed as fibrinous lobar pneumonia caused by Mannheimia (M.) haemolytica. Grossly, lungs were attached onto the pleura by fibrin, with a rich yellowish fluid in thorax. The cut surface of the lung was showed marbled pattern of the reddish or greyish consolidation and widened interlobular septa by fibrin deposition. Histopathologically, parenchymal necrosis was delineated by a band of the degenerated inflammatory cells, and distended interlobular septa with serofibrinous exudates and vascular thrombosis with alveolar capillaries degeneration and abundant serofibrinous exudates in alveoli. M. hemolytica were isolated from all calves, and bovine viral diarrhea virus and parainfluenza type 3 virus in one calf were detected by RT-PCR. Thus, it was concluded that this case was diagnosed as pneumonic mannheimiosis suggested by complex infection with viruses after long-distance transportation and coldness.

Effect of Laser Beam Trajectory on Donor Plate in Laser Induced Thermal Printing Process

  • Lee, Kwang-Won;Lee, Si-Jin;Kwon, Jin-Hyuk;Yi, Jong-Hoon;Park, Lee-Soon
    • Journal of the Optical Society of Korea
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    • v.15 no.4
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    • pp.362-367
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    • 2011
  • Organic ($Alq_3$) film, which was coated on a donor plate, was transferred to an organic light emitting diode (OLED) substrate with help of heat generated by a dithering laser beam. The laser beam was diffracted in an acousto-optic modulator (AOM), then focused on the laser-to-heat converting layer of the donor plate; the focused spot followed trajectories guided by rotation of a Galvano-mirror. Three different functional waveforms, sine wave, square wave, and saw tooth wave were applied to the AOM as modulation signal to generate the dithering beam. The fluorescence microscope images of the donor plate showed that the patterns of removed $Alq_3$ film were affected considerably by the modulation waveforms and the phase difference between adjacent dithering beams. Further, the printed images of Alq3 film on the OLED substrate were different from the patterns of removed Alq3 film. Atomic force microscope images indicated that not only direct transfer but also deposition by sublimated vapor of Alq3 contributed to the pattern formation. Printed patterns affected considerably the electricity-to-light conversion characteristics of OLEDs. For uniform transfer, not only the phase relation of dithering beam lines but also adequate waveform were important.