• 조명전기설비학회논문지
• /
• 제21권7호
• /
• pp.13-19
• /
• 2007

본 연구는 1,080개의 주사선수를 가지는 full-HD PDP를 위한 새로운 고속구동방식에 관한 것으로 고속 어드레스에 의한 표시방전의 방전특성을 고찰하여 새로운 구동방식의 특성을 평가하였다. 이 구동방식에서 어드레스 펄스의 폭이 좁아지면 최초 표시방전의 상대적 방전강도와 방전지연시간은 그 영향을 받는다. 어드레스 펄스의 인가위치의 변화는 방전강도와 무관하나 방전지연시간에는 영향을 미친다. 그러나 어드레스 펄스의 인가위치가 [$6{\mu}s$]이내이고 펄스의 폭이 [$0.7{\mu}s$]이내라면, 어드레스 펄스의 인가위치나 폭에 무관하게 안정된 표시방전을 유도할 수 있다. 실험결과로부터 폭이 좁은 어드레스 펄스를 사용하는 고속구동기술은 축적되는 벽전하의 부족으로 인해 공간전하의 영향에 매우 민감하다는 것을 알았다.

• 폴리머
• /
• 제32권2호
• /
• pp.95-102
• /
• 2008

The $\alpha$,$omega$-diacrylate poly(dimethylsiloxane) (DA-PDMS) containing vinyl ester of versatic acid/vinyl acetate (Veova-10/VAc) was prepared by emulsion copolymerization of (DA-PDMS), Veova-10 (with VAc), and auxiliary agents at $85^{\circ}C$ in the presence of ammonium peroxodisulfate (APS) as an initiator. Sodium dodecyl sulfate (SDS) and nonylphenol ethylene oxide-40 units (NP-40) were used as anionic and nonionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FT-IR). Thermal properties of the copolymers were studied by using thermogravimetric analysis(TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by scanning electron microscopy (SEM) and then the effects of variables such as temperature, agitation speed, surfactant kinds, molecular weights, initiator, and DA-PDMS concentrations on the properties of the silicone-containing Veova-10/VAc emulsions were examined. The calculation of monomer conversion versus time histories indicates that by increasing the DA-PDMS concentration the polymerization rate and the number of polymer particles decrease, respectively.

• Applied Microscopy
• /
• 제24권3호
• /
• pp.87-93
• /
• 1994

In order to elucidate the machinability of lead brass, orthogonal machining experiment was conducted in SEM(Scanning Electron Microscope) equipped with a micro-machining device at a cutting speed of $7{\mu}m/s$ for brass containing 0.2 to 3wt% Pb. The microfactors (i.e., shear angle, contact length between chip and tool) were determined by in-situ observations. Machinability of brass containing lead is discussed in terms of the microfactors and the cutting resistant force tested by lathe cutting. The dynamic behavior of the chip formation of lead brass during the machining process was examined: The chips of lead brass form as a shear angle type. The shear angle increases with the content of lead in (6:4) brass. The pronounced effect of lead on the contact length between chip and tool was observed above 1% Pb. The cutting resistant force tested by lathe decreases remarkably with the lead content in brass. The observed microfactors are in close relation to the tested resistant force in macromachining.

• 한국산업정보학회논문지
• /
• 제22권2호
• /
• pp.35-41
• /
• 2017

본 논문에서는 비전 기술을 이용한 의료용 설문지 인식 시스템 개발을 제안한다. 제안한 시스템은 의료 보건 분야의 지역사회 건강조사에서 사용되는 대량의 설문지를 대상으로 정확한 인식 및 효과적 일괄처리를 할 수 있다. 시스템은 설문지 스캐닝, 답안 인식 및 오류 데이터처리, 결과데이터 검증, 이미지 저장 및 DB구축, 설문결과 분석으로 구성되어 있다. 기존의 자동인식을 위한 시스템과 달리 사용하는 설문의 양식에서 자유롭고, 다양한 표기와 오표기를 처리하여 정확한 인식을 가능하게 한다. 제안한 시스템은 실험을 통해 표기에 대한 98.9% 인식률을 확인하였다.

• Transactions on Control, Automation and Systems Engineering
• /
• 제1권2호
• /
• pp.94-98
• /
• 1999

Optical scanning systems use glavanometers to point the laser beam to the desired position on the workpiece. The angular speed of a galvanometer is typically controlled using Proportional+Integral+Derivative(PID) control algorithms. However, natural variations in the dynamics of different galvanometers due to manufacturing, aging, and environmental factors(i.e., process uncertainty) impose a hard limit on the bandwidth of the galvanometer control system. In general, the control bandwidth translates directly into efficiency of the system response. Since the optical scanning system must have rapid response, the higher control bandwidth is required. Auto-tuning PID algorithms have been accepted in this area since they could overcome some of the problems related to process uncertainty. However, when the galvanometer is attached to a larger mechanical system, the combined dynamics often exhibit resonances. It is well understood that PId algorithms may not have the capacity to increase the control bandwidth in the face of such resonances. This paper compares the achieable performance and robustness of a galvanometer control system using a PID controller tuned by the Ziegler-Nichols method and a controller designed by the Quantitative Feedback Theory(QFT) method. The results clearly indicate that-in contrast to PID designs-QFT can deliver a single, fixed controller which will supply high bandwidth design even when the dynamics is uncertain and includes mechanical resonances.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 추계학술대회 논문집
• /
• pp.272-276
• /
• 2000

Reverse engineering refers to the process that creates a physical part from acquiring the surface data of an existing part using a scanning device. In recent years, as the non-contact type scanning devices become more popular, the huge amount of point data can be obtained with high speed. The point data handling process, therefore, becomes more important since the scan data need to be refined for the efficiency of subsequent tasks such as mesh generation and surface fitting. As one of point handling functions, the cross-sectioning function is still frequently used for extracting the necessary data from the point cloud. The commercial reverse engineering software supports cross-sectioning functions, however, these are only for cross-sectioning the point cloud with the constant spacing and direction. In this paper, adaptive cross-sectioning point cloud which allow the changes of the spacing and directions of cross-sections according to the constant spacing and direction. In this paper, adaptive cross-sectioning algorithms which allow the changes of the spacing and directions of cross-sections according to the curvature difference of the point cloud data are proposed.

• Preventive Nutrition and Food Science
• /
• 제11권1호
• /
• pp.61-66
• /
• 2006

The objective of this study was to compare the color and microstructure of powder, redness, brownness, and antioxidative activity in extruded ginseng, white ginseng and red ginseng extracts. The colors of extruded dry ginseng powder (moisture content 30%, barrel temperature $110^{\circ}C$, and screw speed 200 rpm) were similar to those of red ginseng. Intact cell wall structure was examined in dried root ginseng at $70^{\circ}C$ (A), white ginseng with skin (D), white ginseng without skin (E), and red ginseng (F) under a scanning electron microscope. The cell wall was not detected in samples B and C (dry ginsengs extruded with 25% and 30% moisture contents, respectively). Intact starch granules were detected in samples A, D, and E under a scanning electron microscope. Melted starch granules were detected in samples B, C, and F. Colors (L, a, b) of 50% EtOH extracts were similar in samples C and F. Browniness and redness of extracts were high in extruded dry ginseng and red ginseng extracts. Extruded dry ginseng (B) showed higher electron donation ability and phenolic content than the other samples.

• 한국정밀공학회지
• /
• 제24권8호통권197호
• /
• pp.138-143
• /
• 2007

Microstereolithography technology is similar to the conventional stereolithography process and enables to fabricate a complex 3D microstructure. This is divided into scanning and projection type according to aiming at precision and fabrication speed. The scanning MSL fabricates each layer using position control of laser spot on the resin surface, whereas the projection MSL fabricates one layer with one exposure using a mask. In the projection MSL, DMD used to generate dynamic pattern consists of $1024{\times}768$ micromirrors which have $13.68{\mu}m$ per side. The fabrication range and resolution are determined by the field of view of the DMD and the magnification of the projection lens. If using the projection lens with high power, very fine microstructures can be fabricated. In this paper, the projection MSL system adapted to a large surface for array-type fabrication is presented. This system covers the meso range, which is defined as the intermediate range between micro and macro, with a resolution of a few ${\mu}m$. The fabrication of array-type microstructures has been demonstrated to verify the performance of implemented system.

• 한국정밀공학회지
• /
• 제23권4호
• /
• pp.183-190
• /
• 2006

Digital 3D Real Object Duplication System (RODS) consists of 3D Scanner and Solid Freeform Fabrication System (SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and an industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer (SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. In case of industrial type SFFS, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Dual-Laser Sintering (SDLS) process and 3-axis Dynamic Focusing Scanner for scanning large area instead of the existing f lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, and scan spacing. Now, this study is in progress to evaluate the effect of experimental parameters on the sintering process.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.234.2-234.2
• /
• 2014

Organic light emitting diode (OLED) is considered as the next generation flat panel displays due to its advantages of low power consumption, fast response time, broad viewing angle and flexibility. For the flexible application, it is essential to develop thin film encapsulation (TFE) to protect oxidation of organic materials from oxidative species such as oxygen and water vapor [1]. In many TFE research, the inorganic film by atomic layer deposition (ALD) process demonstrated a good barrier property. However, extremely low throughput of ALD process is considered as a major weakness for industrial application. Recently, there has been developed a high throughput ALD, called 'spatial ALD' [2]. In spatial ALD, the precursors and reactant gases are supplied continuously in same chamber, but they are separated physically using a purge gas streams to prevent mixing of the precursors and reactant gases. In this study, the $Al_2O_3$ thin film was deposited by spatial ALD process. We characterized various process variables in the spatial ALD such as temperature, scanning speed, and chemical compositions. Water vapor transmission rate (WVTR) was determined by calcium resistance test and less than $10-^3g/m^2{\cdot}day$ was achieved. The samples were analyzed by x-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM).