• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.1288-1293
• /
• 2007

The present study covers the design and analysis of a thermionic scanning electron microscope (SEM) column. The SEM column contains an electron optical system in which electrons are emitted and moved to form a focused beam, and this generates secondary electrons from the specimen surfaces, eventually making an image. The electron optical system mainly consists of a thermionic electron gun as the beam source, the lens system, the electron control unit, and the vacuum unit. In the design process, the dimension and capacity of the SEM components need to be optimally determined with the aid of finite element analyses. Considering the geometry of the filament, a three-dimensional (3D) finite element analysis is utilized. Through the analysis, the beam emission characteristics and relevant trajectories are predicted from which a systematic design of the electron optical system is enabled. The validity of the proposed 3D analysis is also discussed by comparing the directional beam spot radius. As a result, a prototype of a thermionic SEM is successfully developed with a relatively short time and low investment costs, which proves the adoptability of the proposed 3D analysis.

• Current Optics and Photonics
• /
• 제2권2호
• /
• pp.140-146
• /
• 2018

In this paper, mesoscale optical surface structures are found to possess both geometric and wave optics features. The study reveals that geometric optic analysis cannot correctly predict the experimental results of light transmission or reflection by mesoscale optical structures, and that, for reliable analyses, a hybrid approach incorporating both geometric and wave optic theories should be employed. By analyzing the transmission patterns generated by the mesoscale periodic pyramid prism plates, we show that the wave optic feature is mainly ascribed to the edge diffraction effect and we estimate the relative contributions of the wave optic diffraction effect and the geometric refraction effect to the total scattering field distribution with respect to the relative dimension of the structures.

• 한국통신학회논문지
• /
• 제21권12호
• /
• pp.3277-3285
• /
• 1996

In this paper, w designed an opical power distribution device for application to an optical switching and an optical subscriber loop. We fabricated PSG thin film by LPCVD. Based on the measured index of fabricted thin film, rib-type waveguide was transformed to two-dimension by the effective index method and we simulated dispersion property to find asingle-mode condition. We found that the optimum design parameters of rib-type waveguide are:cladding layer of 3.mu.m, core layer of 3.mu.m, buffer layer of 10.mu.m, and core width of 4.mu.m. Each side of the guiding region was etched down to 4.mu.m to shape the core. We used these optimum parameters of the rib-type waveguide with branching angle of 0.5.deg. and simulted the Y-branch waveguide by the BPM simulation. Numerical loss in branching area was claculated to be 0.1581dB and equal to the total loss of the Y-branch. The loss of the fabricated Y-branch waveguide on PSG film ws 1.6dB at .lambda.=1.3.mu.m before annealing but was 1.2dB after annealing at 1000.deg. C for 10 minutes. Consequently, the loss of branching area from 3000.mu.m to 6000.mu.m in the z-direction was 0.8dB, and single-mode propagation was confirmed by measuring the near field pattern. For coupling the fabricated Y-branch waveguide with an optical fiber, we fabricated V-groove which was used as the upholder of optical fiber. An etching angle was 54.deg. and the width and depth of guiding groove was 150.mu.m, 70.mu.m, respectively. The optical fiber is inserted onto V-groove. Both the Y-branch and V-groove were connected through the index matching oil. Coupling loss after connecting Y-branch and the optical fiber on V-groove was 0.34dB and that after injecting index mateching oil was 0.14dB.

• 한국멀티미디어학회논문지
• /
• 제3권2호
• /
• pp.112-120
• /
• 2000

본 논문에서는 섬유 제직 공정시 섬유 제품의 질에 영향을 미칠수 있는 섬유 결함, 결함의 위치 검출 뿐만 아니라 이동중인 섬유의 왜곡각 분류 및 섬유의 밀도를 측정할 수 있는 실시간 섬유 성량 검사 시스템을 구현하였다. 구현된 시스템에서는 잡음 문제와 실시간 처리를 위하여 광학적 렌즈로부터 섬유의 위사 부분만을 추출한 후 영역 교차법을 적용하여 섬유의 밀도를 측정하였으며, 획득된 위사 영상으로부터 평균 기울기와 가우시안 기울기 분류자를 사용하여 고속 이동 섬유 가공 공정시 발생할 수 있는 섬유의 왜곡각 분류를 통해 왜곡각 보정을 하였다. 또한 명암도 상관 행렬 특징자를 이용하여 섬유의 결함 검사와 겸함 위치를 추출하도록 하였다. 제안한 알고리즘을 적용하여 구현한 섬유 성량 검사 시스템은 고속 이동 섬유 가공 공정에 있어서 실시간으로 섬유의 밀도 계산과 섬유 결함 검출이 가능하며 섬유 염색, 제직 및 가공공정에 있어서 섬유의 상태를 모니터링 및 제어함으로써 고품질의 섬유 제품 생산이 가능하다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 추계학술대회논문집
• /
• pp.391-394
• /
• 2003

Laser direct writing process is developed 3rd harmonic Diode Pumped Solid State Laser with the near visible wavelength of 355 m sensitive polymer is irradiated by UV laser and developed using polymer solvent to obtain quasi-3D. It is important to reduce line width for image mode waveguides, so some investigations will be carried out in various conditions of process parameters such as laser power, writing speed, laser focus and optical properties of polymer. This process could be to fabricate a single mode waveguide without expensive mask projection method. Experimentally, the patterns of trapezoidal shape were manufactured into dimension of 8.4 mm width and 7.5 mm height. Propagation loss of straight waveguide measured 3 dB/cm at 1,550 nm.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 추계학술발표대회
• /
• pp.27.1-27.1
• /
• 2009

In recent years, ZnO nanostructures have drawn considerable attentions for the development of futuristic electronic devices due to their superior structural and optical properties. As the growth of ZnO nanowires by MOCVD is a bottom-up technique, the nature of substrates has a vital role for the dimension and alignment of the nanowires. However, in the pursuit of next generation ZnO based nanodevices, it would be highly preferred if well-ordered ZnO nanowires could be obtained on various substrates like sapphire, silicon, glass etc. Vertically aligned nanowires were grown on A and C-plane sapphire substrates, where as nanopencils were obtained on R-plane sapphire substrates. In addition, C-axis oriented vertical nanowires were also found using an interfacial layer(aluminum nitride film) on silicon substrates. On the other hand, long nanowires were found on Ga-doped ZnO film on glass substrates. Structural and optical properties of the ZnO nanowires on various substrates were also investigated.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.234-237
• /
• 2002

To detect external vibration signals on the latticed fence structure, distributed fiber optic sensor using Sagnac interferometer was fabricated and tested. The latticed structure fabricated with dimension of 170cm in width and 180cm in height, the optical fiber, 50m in length, distributed and fixed on the latticed structure. It was verified the sensitivity of the Sagnac interferometer using the PZT phase modulator. Fiber optic external vibration signal spplied to the latticed fence structure from 100Hz to several kHz. The interferometeric fiber optic sensor detected the excited vibration signal very effectively without any signal processing. The detected optical signals were compared and analyzed to the detected acclerometer signals.

• 전기전자학회논문지
• /
• 제22권2호
• /
• pp.446-454
• /
• 2018

In this work, we summarize the calculation processes of obtaining a scattering factor using with the equilibrium average projection scheme (EAPS), with moderately weak coupling (MWC) interaction, and obtain the line-shape formula of an electron-deformation phonon interacting system interested in the confinement of electrons by squarwell confinement potentials in quantum two dimensional system.. Through the numerical analysis, we analysis the magnetic dependence of absorption power, P(B) in several temperature and frequency difference dependence of absorption power $P({\Delta}{\omega})$, in several external field, where ${\Delta}{\omega}={\omega}-{\omega}_0$ and ${\omega}({\omega}_0)$ is the angular frequency (the cyclotron resonance frequency). The result of equilibrium average projection scheme (EAPS) in SER-MWC explains the properties of quantum transition quite well.

• 전자공학회논문지B
• /
• 제30B권2호
• /
• pp.78-86
• /
• 1993

A nonlinear method for directional information processing is introduced, along with an application of directional feature enhancement. In this method, an input is convolved with a 2-D ong, norrow kernel, which is rotated through 360 degree, continuously or discretely in a large number of steps. An output is given by some function of the convolution results. Linear features that are aligned with the kernel are enhanced, otherwise, removed or suppressed. The method presented is insensitive to variation in the dimension of linear features to be processed and preserves a good enhancement capability even for an image characterized by low contrast and spatially varying brightness in noisy backgroung. Effects of the kernel legnth and width on the performance are discussed. A possible hybrid optical-electronic implementation is also discussed.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.792-796
• /
• 2003

In this paper, to detect external sound frequency on the latticed structure, fiber optic sensor net using Sagnac interferometer was fabricated and tested. The latticed structure fabricated with dimension of 50cm in width and 50cm in height, the optical fiber, 50m in length, distributed and fixed on the latticed structure. Single mode fiber, a laser with 1,550nm in wavelength, 2${\times}$2 coupler were used. External sound signal applied to the fiber optic sensor net and the detected optical signals were compared and analyzed to the detected microphone signals against time and frequency domain. Based on the experimental results, fiber optic sensor net using Sagnac interferometer detected external sound frequency, effectively. This system can be expanded to the structural health monitoring system.