• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.7
• /
• pp.701-706
• /
• 2015

In this study, experimental and computer simulation results are compared and analyzed. Three-dimensional (3D) fabricated matrices from an MJM 3D printer were joined with poly-acetate thermoplastic polymers using a diode laser. A power range of 5-7 W was used to irradiate the boundary of two polymers. The heated polymers flowed into the matrices of the 3D fabricated structure, and reliable mechanical joining was achieved. Computer simulation showed the temperature distribution in the polymers, and flow direction was estimated based on the flux and temperature information. It was found that the more than the minimum energy threshold was required to effectively join the polymers and that two scans at low-speed were more effective than four scans at high speed.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2003.09a
• /
• pp.80-80
• /
• 2003

디지털 의료영상 획득기술과 컴퓨터 및 네트워크 기술의 발달로 현재 각 병원에서는 PACS(Picture Archiving and Communication System)를 설치하여 필름을 사용하지 않고 진단과 진료를 하는 병원이 증가하고 있으며, 이에 따라 기존 필름상태의 의료영상은 필름디지타이저로 디지털 영상화한 후 모니터를 통하여 판독과 진료에 이용하고 있다. 본 연구에서는 현재 세브란스병원에서 사용되고 있는 CCD 방식 필름디지타이저와 레이저 스캐너방식 필름디지타이저의 픽셀값 균일도에 대해 중점적으로 비교, 분석하고자 한다. 픽셀값 균일도 측정을 위해 필름프린터를 이용하여 균일한 광학밀도를 가진 필름을 출력하였다. 그 테스트 필름은 각 사분면에 각기 다른 광학밀도를 가지고 있었으며, 그 광학밀도 값은 각각 0.19, 0.71, 1.41, 그리고 3.10 이었다. 제작된 필름은 레이저 (Model 2905, Array Corp., Japan) 방식과 CCD 방식 (SEDAS Media Film Scanner, Kodak, japan) 디지타이저에 의해 디지털화 되었다. 그 영상들은 다시 분석을 위해 PACS를 통해 PC로 전송되어졌고 자체 제작된 소프트웨어를 이용하여 균일도에 대한 분석을 수행하였다. 하나의 사분면 영상에 대하여 일정한 간격과 크기로 20개의 ROI를 만들고, 그 내부의 픽셀값들의 평균값을 구하여 그 영역의 대푯값으로 하였다. 그 대푯값들 중 최대값과 최소값의 차이에 대한 백분율로써 균일도를 표시하였다. 그 결과 광학밀도가 0.19인 사분변의 영상에서의 균일도는 레이저 방식 및 CCD 방식 각각에서 99.8%, 94.3%였으며, 0.71인 사분면에서는 99.4%, 75.6%, 1.41 일때는 97.9%, 62.96%, 그리고 3.1인 사분면에서는 82.7%, 53.7%였다. 같은 광학밀도를 가진 사분면에서는 레이저방식의 균일도가 CCD 방식에 비해 더 우수함을 알 수 있었으며, 같은 방식에서 얻은 영상이라 할지라도 광학 밀도값이 높은 사분변에서 얻은 영상일수록 균일도가 떨어짐을 알 수 있었다. 결론적으로, 레이저 방식 필름 디지타이저는 균일도 면에서도 CCD 방식에 비해 우수함을 알 수 있었으며 CCD 방식은 백라이트의 균일도가 영상의 균일도에 영향을 미칠수도 있는 만큼 향후 거기에 대한 연구도 이루어져야 할 것으로 생각된다.

• Korean Journal of Optics and Photonics
• /
• v.8 no.2
• /
• pp.165-168
• /
• 1997

We have constructed a scanning confocal microscope using a 780 nm semiconductor laser, an actuator of a compact disk player and a quad-detector. This device detects heights and characteristics of a surface. The laser focus was located at the surface of a sample by using the error signal obtained by a quad-dector, and the current supplied to the actuator for lens was displayed as a height. The materials of a surface were classified according to reflected total intensities and was displayed by different color in a monitor. The device has very samll dimensions of 30 mm$\times$20 mm$\times$20 mm and scan field is 1.6 mm$\times$1.6mm. We obtained two images, one using only reflected light and the other using an error signal from a quad-detector and compared these two images.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.5 s.248
• /
• pp.413-421
• /
• 2006

The bubble dynamics induced by direct laser heating is experimentally analyzed as a first step to assess the technical feasibility of laser-based ink-jet technology. To understand the interaction between laser light and ink, the absorption spectrum is measured for various ink colors and concentrations. The hydrodynamics of laser-generated bubbles is examined by the laser-flash photography. When an Ar ion laser pulse (wavelength 488 nm) with an output power up to 600 mW is incident on the ink solution through a transparent window, a hemispherical bubble with a diameter up to ${\sim}100{\mu}m$ can be formed with a lifetime in a few tens of microsecond depending on the laser power and the focal-spot size. Parametric study has been performed to reveal the effect of laser pulse width, output power, ink concentration, and color on the bubble dynamics. The results show that the bubble generated by a laser pulse is largely similar to that produced by a thin-film heater. Consequently, the present work demonstrates the feasibility of developing a laser-actuated droplet generation mechanism for applications in ink-jet print heads. Furthermore, the results of this work indicate that the droplet generation frequency is likely to be further increased by optimizing the process parameters.

• Korean Journal of Optics and Photonics
• /
• v.10 no.1
• /
• pp.15-20
• /
• 1999

Laser Scanning Unit (LSU), which is one of the core parts of laser printer, consists of LD Module, cylinder lens, polygon mirror and f$\theta$ lens. After making an initial design on each part, we optimized the one which satisfies the user specification. The optimized optical system has diffraction limited performance for the slit size of 2.7 mm$\times$1.6 mm, f$\theta$ characteristics less than 0.3% and field curvature less 1.2 mm. We also calcurate tolerance of each part based on RSS(Root Sum Square) method to manufacture LSU for mass production.

• Annual Conference on Human and Language Technology
• /
• 1989.10a
• /
• pp.132-136
• /
• 1989

본 논문에서는 한국과학기술원 전산학과 인공지능연구실에서 개발하고 있는 한글 문서 인식 시스템 SILNOON을 소개한다. 본 연구는 인쇄체 한글로 작성된 문서를 자동으로 인식하여 컴퓨터 화일로 저장하고, 인식된 문서를 편집 및 수정하여 레이저 프린터를 통하여 출력할 수 있는 실용적인 한글 문서 인식 시스템의 개발을 그 목적으로 하고 있다. SILNOON 시스템은 크게 전처리, 문자 인식, 후처리 등의 세 단계로 구성되어 있다. 본 논문에서는 SILNOON 시스템의 각 구성 단계에 대하여 설명하고 개인용 컴퓨터 상에서 구현되어 있는 시제품을 가지고서 실험한 결과를 발표한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.4
• /
• pp.386-390
• /
• 2006

Global consumption of aspheric lens will expand rapidly due to golbal transformation of the electronics based industry to optics based mechatronics. Especially, F-Theta lens is one of important parts in Laser Scanning Unit(LSU) because it affects the optical performance of LSU dominantly. Non axisymmetric machine based processing techologies are required to obtain high accuracy in utlra-precision aspheric core, the most important component in plastic injection molded F-Theta lens assembly. In this study, the core with non-axisymmetric aspheric shape which is used to emit the F-Theta lens was processed using the ultra precision processing technology and the shape accuracy of the core was measured. And the results there of were evaluated and compared with the emitted shape accuracy of F-Theta lens.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.4
• /
• pp.53-60
• /
• 1998

The purpose of this paper is to meausre the electrophotographic characteristics of double-layered organic photoreceptor and to evaluate an application for the laser beam printer drum. The characte carrier generation layer(CGL) of double-layered photoreceptor was fabricated with .tau.-H$_{2}$Pc which has high photosensitivity in the near-infrareed region(thickness is about 0.3.mu.m), and Oxadiazole derivative was chosen as a charge carrier transport layer(CTL) because of its high hole mobility. To observe the electrophotographic characteristics of the photoreceptor, we measured the charge acceptance, dark-decay ratio, residual potential after light irradiation. From the result of this study, proper thickness of CTL was about 10.mu.m. Also it's realized that electrophotographic characteristics of the photoreceptor were depend on the thickness of the CTL and the initial surface potential.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.189-193
• /
• 2001

The performance of printer can be determined by the printing speed, noise level, printing quality which includes the resolution, regularity of printed matter and etc. Among them, printing quality mostly depends on the irregularity of the line spacing and dot size. The irregular line spacing and dot size in laser beam printer are mainly from the jitter which comes from the vibration of Organic Photo Conductive(OPC) drum and the Laser Scanning Unit(LSU). Jitter due to the vibration of LSU appears as high-frequency component which occurs 100-300$\mu\textrm{m}$ interval in printed matter and the causes of it can be estimated as the vibration of polygon motor, case, reflecting mirror and etc. In this paper, vibration characteristics of the LSU under development are investigated and the strategy for improvement of the dynamic characteristics is established and its validity is demonstrated.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.854-855
• /
• 2015

Electric machines for office automation device such as printer and scanner have been required the low noise and vibration performance. Many researches about the low noise and vibration of polygon mirror scanner motor have been also progressed. The noise and vibration of polygon mirror scanner motor can be classified by aerodynamic, structural and electromagnetic. Electromagnetic noise and vibration can be occurred by high cogging torque and nonsinusoidal back EMF. To improve the cogging torque and back EMF characteristic, we apply unequal air-gap. To analyse characteristic of a polygon mirror scanner motor, two dimensional finite element method is used. To minimize the cogging torque of a polygon mirror motor, Kriging based on latin hypercube sampling (LHS) is utilized. As a result, the cogging torque and torque ripple improved while maintaining the back EMF and average torque.