• 한국진공학회지
• /
• 제15권5호
• /
• pp.493-498
• /
• 2006

MOCVD로 성장된 InGaAs 양자점을 이용하여 $1.5{\mu}m$의 발광파장을 갖는 고휘도 발광소자 (Superluminescent diode, SLD)를 제작하였다. 상온에서 SLD의 광출력은 CW 3 mW 였고, 3-dB 파장대역폭은 55 nm 이었다.

• 한국공작기계학회논문집
• /
• 제16권5호
• /
• pp.24-32
• /
• 2007

Laser surface hardening is beneficially used for surface treatment of structural steel. Due to very rapid heating and cooling rates, structural low-alloy steel(SCM4) can be hardened as self quenching. The aim of this research project is to improve the influence of the process laser parameters: laser power, spot size, surface roughness, and traverse speed. The laser beam is allowed to scan on the surface of the workpiece at the constant power(1095W), varying the traverse speed at 0.3m/min, 0.5m/min and 0.8m/min. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with uniform hardness. From the results of the experiment, it has been shown that the stable hardness is about 600$\sim$700Hv, when the laser power, focal position and the traverse speed are P=1095W, z=0mm and v=0.3m/min.

• 한국정밀공학회지
• /
• 제22권11호
• /
• pp.51-58
• /
• 2005

Laser surface hardening technologies have been used to improve characteristics of wear and to enhance the fatigue resistance for automotive parts. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser heat treatment for the case of SM45C medium carbon steel. CW Nd:YAG laser is selected as the heat source. The optical lens with the elliptical profile is designed to obtain a wide heat treatment area with a uniform hardness. From the results of the experiments, it has been shown that the maximum hardness is approximatly 780 Hv when the power and the travel speed of laser are 1,095 W and 0.6 m/min, respectively. In addition, the hardening width using the elliptical lens was three time larger than that using the defocusing of laser beam.

• 한국ITS학회 논문지
• /
• 제10권5호
• /
• pp.71-78
• /
• 2011

본 논문은 GaN HEMT (Gallium Nitride High Electron Mobility Transistor)를 이용하여 Class-J 모드를 적용한 고효율, 광대역 특성을 갖는 전력증폭기를 설계 및 제작하였다. 제안된 Class-J 모드 전력증폭기의 정합회로는 2차 고조파 임피던스가 리액턴스 성분만 갖도록 하였으며, 1.4 ~ 2.6 GHz 주파수대역내에서 연속파 (CW) 신호를 사용하여 $40{\pm}1$ dBm의 출력 전력과 50 % 이상의 전력부가효율 (Power-Added Efficiency, PAE) 및 60 % 이상의 드레인 효율 (Drain Efficiency, DE)이 측정되었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.219.1-219.1
• /
• 2014

전자소자 산업의 미세화 및 대형화에 따라 플라즈마 밀도, 전위, 온도, 균일도 등 과 같은 플라즈마 특성을 제어하는 것은 차세대 플라즈마 장치 개발에 있어 매우 중요한 요소라고 할 수 있다. 특히, 급격한 소자의 미세화에 따라 플라즈마 공정을 통해 발생할 수 있는 damage는 큰 issue가 되어 왔고, 많은 연구자들은 이를 해결하기 위해서 다각적인 노력을 진행해 왔다. 그중 높은 전자 온도는 높은 전자 에너지에 의해 공정 중 소자를 손상 시키는 주된 원인이라고 보고되고 있으며, 이에 대한 제어기술은 매우 중요하다고 할 수 있다. 본 연구에서는 서로 다른 두 개의 내/외측으로 나뉘어진 나선형 모양의 ICP 안테나를 이용 하여 연구를 진행하였다. 내측의 안테나에는 2 MHz를 연결 하였으며, 외측의 안테나에는 13.56 MHz를 연결 하였으며, 내/외측 안테나에 각각 pulse mode로 입력전력을 인가해 줌으로써 플라즈마의 특성을 관찰하였다. Pulse / CW (Continuous Wave) mode에 있어서 전자온도의 측정을 위해 emissive probe 를 이용하여 plasma potential과 floating potential을 측정하였으며, 이를 통하여 전자온도를 계산하여 구할 수 있었다. Duty ratio 및 pulsing frequency의 변화에 따른 전자온도의 변화를 확인 할 수 있었으며, 그에 따른 플라즈마 균일도를 ion saturation current를 측정함으로써 관찰할 수 있었다. 실제 식각 공정에 있어서 Pulsing 조건에 따른 식각 특성을 관찰하기 위해, SiO2, ACL (Amorphous Carbon Layer)에 대해 식각을 진행하였으며, 식각 메커니즘 분석을 위해 이온에너지 분포의 변화를 PSM (Plasma Sampling Mass-spectroscopy)을 이용하여 측정하였다.

• 한국정밀공학회지
• /
• 제24권4호
• /
• pp.57-67
• /
• 2007

Laser surface hardening technologies have been used to improve characteristics of wear and to enhance the fatigue resistance fur mold parts. The objective of this research work is to investigate the influence of the process parameters, such as power of laser and defocused spot position, on the characteristics of laser surface hardening for the case of SKD61 steel. CW Nd:YAG laser is selected as the heat source. The optical lens with the elliptical profile is designed to obtain a wide surface hardening area with a uniform hardness. From the results of the experiments, it has been shown that the maximum average hardness is approximatly 780 Hv when the power, focal position and the travel of laser are 1,095 W, 0mm and 0.3 m/min, respectively. In samples treated with lower scanning speeds, some small carbide particles appear in the interdendritic regions. This region contains fine martensite and carbide in proportions which depend on the local thermal cycle.

• 한국자동차공학회논문집
• /
• 제17권3호
• /
• pp.35-44
• /
• 2009

The purpose of this paper is to describe experimental results about the T-joint welding of the high power continuous wave (CW) fiber laser for SAPH steel plate for seat frame of car. The seat rail is a part of seat frame of cars. The assembling method is mostly fix up using a bolt and nut. But this assembling method has many demerits in productivity such as increasing work process and material cost. This paper presents an experimental study about Laser T-Joint weldability of seat rail. Laser welding has many advantages in lightness and saving material costs of seat frame. The laser beam was moved along the work pieces by six axis robot with process optical fiber. The laser beam is focused with a welding head within incident angle $15{\sim}45^{\circ}$ for the purpose of the T-joint welding through two side full penetration. The range of the root gap size is less than ${\leq}0.4mm$. Optical microscopy SEM were performed to observe the micro structures and determine the structures of welded zone.

• 한국생산제조학회지
• /
• 제20권3호
• /
• pp.342-349
• /
• 2011

The purpose of this paper is to describe experimental results about the butt welding and bead on plate welding of the high power Continuous Wave (CW) Fiber laser for Ultra-low carbon Interstitial Free(IF) steel plate for gear part of car. After being welded of the gear parts by the fiber laser and electron beam Microstructures of melting zone had been mixed acicular, granular bainitic, quasi-polygonal and widmanstatten ferrite because of a radical thermal diffusion after welding, difference of critical volume and grain size. As a result of experiment, when gear parts were welded by the fiber laser and electron beam, the fiber laser welding has been stable properties without internal defects more than the electron beam welding. Therefore it has the very advantages of welding high quality and productivity more than conventional melting method. The optimal welding processing parameters for gear parts were as follows : the laser power and welding speed were 3kWatt, 30mm/sec respectively. At this time heat input was $21.2{\times}10^3J/cm^2$.

• 전기전자학회논문지
• /
• 제15권4호
• /
• pp.313-318
• /
• 2011

10 GHz 고조파 모드잠금 고리형 반도체 광섬유 레이저의 외부 CW 광주입 효과를 연구하였다. 선폭 ~ 100 KHz의 코히어런트 외부 광주입에 의해 40 dB가 넘는 스펙트럼 빗살의 골짜기와 30 dB가 넘는 슈퍼모드 비팅 잡음 억제효과를 얻을 수 있었다. 저가의 주입광원을 이용할 수 있는지를 조사하기 위해 주입광을 대략 10 MHz의 선폭을 갖는 DFB 레이저로 교체하였다. 그 결과, 스펙트럼 빗살의 골짜기는 유사한 특성을 보였으나, 슈퍼모드 비팅 잡음은 억제되기보다는 오히려 증가하는 것으로 관측되었다.

• 한국통신학회논문지
• /
• 제25권3B호
• /
• pp.504-509
• /
• 2000

This paper presents a noble operation and maintenance system for the optical subscriber loops and its feasibility through several experiments. In this system, a broadband CW (Continuous Wave) light source I used as monitoring of testing signals. and a FGF(Fiber Grating Filter) of which reflective wavelength is independent, is inserted somewhere in each subscriber loop for the reflection of monitoring of testing signals. The propose of the system is quick decision. whether the loop is just fault or not. rather than detailed information of loop state. At present, most of operation and maintenance system for the optical subscriber loops adopts OTDR(optical time domain reflectometer) for testing function. the OTDR is useful for detailed test, but not adequate for simple test because of long testing time . And it is difficult to test PON network by using general OTDR that has a single-wavelength light source. Compared to using OTDR, the proposed system can afford to shorten testing time and to test PON network. Moreover, we can cut down the system cost by simplifying circuits of the optical light sources. Our results show that the proposed system operates well according to the purpose mentioned above.