• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.254-257
• /
• 2009

The crystallization and activated annealing effect of Si films using an excimer laser and a new CW blue laser are described comparing with furnace annealing (SPC) for the application of advanced TFTs and future applications. Currently, pulsed ELA is used extensively as a LTPS process on glass substrates as the efficiency is high in UV region for thin Si film of 40- 60 nm thickness. ELA enables extremely low resistivity for both n- and p-typed Si films. On the other hand, CW BLDA enables the smooth Si surface having arbitral grains from micro-grains to anisotropic huge grain structure only controlling its power density.

• 한국광학회지
• /
• 제32권2호
• /
• pp.62-67
• /
• 2021

본 연구에서는 모드 잠금된 ps-펄스 광섬유 레이저와 연속 발진하는 좁은 선폭의 반도체 레이저를 이용하여 주기적 분극반전된 LiNbO3(periodically poled lithium niobate; PPLN) 결정에서 합주파수 생성 연구를 수행하였다. 모드 잠금된 펄스 레이저는 중심 파장이 1560.7 nm이고 스펙트럼의 폭은 약 1.1 nm이며, 연속 발진 반도체 레이저는 중심 파장이 1551 nm이고 스펙트럼의 폭은 약 6 MHz로 동작한다. 합주파수 생성을 효과적으로 수행하기 위해서 하나의 단일 모드 광섬유를 이용하여 PPLN 결정 내부에서 두 펌프 광원을 공간적으로 완전히 중첩하였다. 모드 잠금된 펄스 레이저와 좁은 선폭의 연속발진 반도체 레이저에 의해서 모드 잠금된 펄스 형태의 778 nm인 합주파수 생성을 스펙트럼과 시간적인 변화로 확인하였다. 본 연구 결과는 주파수 제어가 가능한 광주파수 빗(optical frequency comb)을 이용한 광주파수 측정 및 고분해 레이저 분광 연구 등 다양하게 응용될 수 있을 것으로 기대된다.

• 한국레이저가공학회지
• /
• 제12권3호
• /
• pp.7-13
• /
• 2009

The process of thermal-degradation of thin-film polymeris studied in this work for various laser sources from CW to fs. Samples composed of a thin polymer layer sandwiched between two glass plates are irradiated by the lasers and the threshold irradiance of polymer carbonization is experimentally measured. In the numerical analysis, the transient temperature distribution is calculated and the number density of carbonization in the polymer layer is also estimated. It is shown that pulsed lasers can result in more uniform distribution of temperature and carbonization than the CW laser.

• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 1999년도 춘계학술대회 논문집
• /
• pp.26-31
• /
• 1999

As a part of work to simulate electromagnetic environments for Hareware-In-the-Loop Simulation, clutter signals of pulsed dopplar radar(altimeter) and CW radar are modeled as numerical expressions for various parameters. The simulated results show that this method is applicable to simulate complex electromagnetic environments.

• 접착 및 계면
• /
• 제10권1호
• /
• pp.17-22
• /
• 2009

Polymer thin films were prepared by radio frequency (RF) plasma polymerization of phthalic anhydride (PA). First, monomer vaporization temperature ($100{\sim}160^{\circ}C$) was optimized by evaluating the thermal properties of thin films using differential scanning calorimeter (DSC) and measuring the root-mean-square (RMS) roughness with atomic force microscope (AFM) at the fixed plasma power of 10 W and time of 5 min in a continuous-wave (CW) mode. Plasma power (5~20 W) was then optimized by measuring the film solubility in solvents such as toluene, acetone, dimethylsulfoxide (DMSO) and 1 methylpyrrolidine (NMP). Next, pulsed mode plasma polymerization was also studied by varying the duty cycle of on-time (5, 20%) under optimized conditions of continuous-wave (CW) mode ($120^{\circ}C$, 10 W) in order to increase the anhydride functional groups. Finally, polymer thin films were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA) and ${\alpha}$-step.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1998년도 추계학술대회
• /
• pp.213-214
• /
• 1998

The important role of the ultrasonic Doppler system in the modem clinical medicine is to provide the clinical information of the vascular system. The ultrasonic pulsed wave(PW) Doppler system, a kind of the ultrasound Doppler system, is more available than the ultrasonic continuous wave(CW) Doppler system because it can evaluate the velocity and the direction of blood flow as well as the depth of vessel. However, the ultrasonic PW Doppler system has the disadvantage that the range of evaluating velocity of blood flow is limited(Nyquist limit). In order to solve this limit, we propose the algorithm for eliminating this aliasing in this paper. In addition, we propose the efficient signal processing algorithm.

• Journal of Oral Medicine and Pain
• /
• 제19권1호
• /
• pp.9-15
• /
• 1994

This experiment was performed to confirm the hypothesis that LLLT had biostimulation effect for all kinds of cells and there would be differences in the growth of cells among different types of pulsed laser. 360 samples were used in this study. The samples were randomly divided in 6 groups according to the pulse type : quasi continuous type (CW), pulse 1(P1), pulse 7(P7), pulse 9(P9), pulse 15(P15) and shame-irradiated control(Co) groups. Energy fluences of all experimental groups, P1, P7, P9, P15 and CW were 2.12, 2.12, 6.37, 57.32 and 31.85 mj/cm2 respectively. All samples were irradiated for every 1 minute at 0, 12, 24, 36, 48 and 60 hours. Ten samples of each group were sacrificed at 0 and every 12 hours and then the optical density of all samples was measured with the spectrophotometer. As a result, some types of pulses showed significant differences among groups. The increase of cells were markedly stimulated with laser irradiation in P7 and P9 groups, while inhibited in CW, P1, and P15 groups compared with control group. It is therefore, suggested that specific laser pulse should be recommanded to have the biostimulation effects on the specific tissue or cells, although the biostimulation effect is does dependant.

• 한국재료학회지
• /
• 제30권7호
• /
• pp.327-332
• /
• 2020

Laser induced surface activation (LISA) technology requires refined selection of process variables to fabricate conductive microcircuits on a general polymer material. Among the process variables, laser mode is one of the crucial factors to make a reliable conductor pattern. Here we compare the continuous wave (CW) laser mode with the pulse wave (PW) laser mode through determination of the surface roughness and circuit accuracy. In the CW laser mode, the surface roughness is pronounced during the implementation of the conductive circuit, which results in uneven plating. In the PW laser mode, the surface is relatively smooth and uniform, and the formed conductive circuit layer has few defects with excellent adhesion to the polymer material. As a result of a change of laser mode from CW to PW, the value of Ra of the polymer material decreases from 0.6 ㎛ to 0.2 ㎛; the value of Ra after the plating process decreases from 0.8 ㎛ to 0.4 ㎛, and a tight bonding force between the polymer source material and the conductive copper plating layer is achieved. In conclusion, this study shows that the PW laser process yields an excellent conductive circuit on a polymeric material.

• Current Optics and Photonics
• /
• 제3권5호
• /
• pp.466-472
• /
• 2019

A system for continuous-wave coherent Doppler lidar (CW lidar), made up of all-fiber structures and a coaxial transmission telescope, was set up for wind measurement in Hefei (31.84 N, 117.27 E), Anhui province of China. The lidar uses a fiber laser as a light source at a wavelength of $1.55{\mu}m$, and focuses the laser beam on a location 80 m away from the telescope. Using the CW lidar, radial wind measurement was carried out. Subsequently, the spectra of the atmospheric backscattered signal were analyzed. We tested the noise and obtained the lower limit of wind velocity as 0.721 m/s, through the Rayleigh criterion. According to the number of Doppler peaks in the radial wind spectrum, a classification retrieval algorithm (CRA) combining a Gaussian fitting algorithm and a spectral centroid algorithm is designed to estimate wind velocity. Compared to calibrated pulsed coherent wind lidar, the correlation coefficient for the wind velocity is 0.979, with a standard deviation of 0.103 m/s. The results show that CW lidar offers satisfactory performance and the potential for application in wind measurement.

• Journal of Information Display
• /
• 제11권1호
• /
• pp.12-16
• /
• 2010

The effect of the crystallization and activated annealing of Si films using an excimer laser and the new CW blue laser are described and compared with furnace annealing for application in advanced TFTs and for future applications. Pulsed excimer laser annealing (ELA) is currently being used extensively as a low-temperature poly-silicon (LTPS) process on glass substrates as its efficiency is high in the ultra-violet (UV) region for thin Si films with thickness of 40-60 nm. ELA enables extremely low resistivity relating to high crystallinity for both the n- and p-type Si films. On the other hand, CW blue laser diode annealing (BLDA) enables the smooth Si surface to have arbitral crystal grains from micro-grains to an anisotropic huge grain structure only by controlling its power density. Both annealing techniques are expected to be applied in the future advanced TFT systems.