• E2M - 전기 전자와 첨단 소재
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• 제9권6호
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• pp.593-599
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• 1996

Laser scribing of silicon plays an important role in metallization including the grid pattern and the front surface geometry which means aspect ratio of metal contacts. To make a front metal electrode of buried contact solar cell, we used ND:YAG lasers that deliver average 3-4W at TEM$\_$00/ mode power to sample stage. The Q-switched Nd:YAG laser of 1.064 gm wavelength was used for silicon scribing with 20-40.mu.m width and 20-200.mu.m depth capabilities. After silicon slag etching, the groove width and depth for buried contact solar cell are -20.mu.m and 30-50.mu.m respectively. Using MEL 40 Nd:YAG laser system, we can scribe the silicon surface with 18-23.mu.m width and 20-200.mu.m depth controlled by krypton arc lamp power, scan speed, pulse frequency and beam focusing. We fabricated a buried contact Silicon Solar Cell which had an energy conversion efficiency of 18.8 %. In this case, the groove width and depth are 20.mu.m and 50.mu.m respectively.

• 한국전기전자재료학회논문지
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• 제23권4호
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• pp.280-286
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• 2010

We have investigated the influence of rapid thermal annealing (RTA) temperature on properties of Al-doped zinc oxide (AZO) thin films deposited on glass substrate by using radio-frequency magnetron sputtering. The RTA is performed in a nitrogen ambient in the temperature range from 300 to $600^{\circ}C$ for 1 minute in a rapid thermal annealer after growing the AZO thin films. The crystallographic structure and the surface morphology of AZO thin film are measured by using X-ray diffraction, and atomic force microscopy and scanning electron microscopy, respectively. The optical transmittance of the deposited thin films is examined in the wavelength range of 300-1100 nm, where the average transmittance is above the 90% in the visible and near-infrared regions. The optical bandgap is calculated from the Tauc's model, and it shows a significant dependence on the RTA temperature. As for the electrical properties of the thin films, the AZO thin film annealed at $400^{\circ}C$ shows the lowest electrical resistivity of $8.6{\times}10^{-3}{\Omega}cm$ and the Hall mobility of $11.3cm^2$/V-sec. These results suggest that the RTA temperature is an important parameter to influence on the structural, electrical, and optical properties of AZO thin films.

• 대한전자공학회논문지SD
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• 제39권4호
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• pp.55-62
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• 2002

양방향 ADM 노드에서 자동이득제어를 위해 발진고리형 고정이득 EDFA를 적용할 경우 잡음지수 특성을 검토하고자 한다. 이를 위해 소신호 입력인 경우에 한해서 발진보상광의 발진방향 및 발진파장에 따른 잡음지수 특성을 평균밀도반전 알고리즘에 의해 계산하였고 실험적으로 확인하였다. 그 결과 단파장의 발진보상광이 광섬유고리에서 후방 발진을 일으킬 경우가 양방향의 소신호 잡음지수 측면에서는 가장 양호한 조건으로 판명되었다.

• International Journal of Precision Engineering and Manufacturing
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• 제5권3호
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• pp.19-25
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• 2004

Pitch measurements of 150 nm one-dimensional grating standards were carried out using a contact mode atomic force microscopy with a high resolution three-axis laser interferometer. This measurement technique was named as the 'nano-metrological AFM'. In the nano-metrological AFM, three laser interferometers were aligned precisely to the end of an AFM tip. Laser sources of the three-axis laser interferometer in the nano-metrological AFM were calibrated with an I$_2$ stabilized He-Ne laser at a wavelength of 633 nm. Therefore, the Abbe error was minimized and the result of the pitch measurement using the nano-metrological AFM could be used to directly measure the length standard. The uncertainty in the pitch measurement was estimated in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM). The primary source of uncertainty in the pitch-measurements was derived from the repeatability of the pitch-measurements, and its value was about 0.186 nm. The average pitch value was 146.65 nm and the combined standard uncertainty was less than 0.262 nm. It is suggested that the metrological AFM is a useful tool for the nano-metrological standard calibration.

• 한국세라믹학회지
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• 제42권2호
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• pp.127-131
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• 2005

열처리가 단분산 구형 $SiO_2$ 나노 분말의 자기조립을 통하여 형성된 광자결정 박막의 광특성에 미치는 영향에 대하여 조사하였다. 광밴드갭에 의해 나타나는 반사율 피크는 열처리 온도가 증가함에 따라 단파장 쪽으로 이동하였고, 빛의 회절에 의해 나타나는 Fabry-Perot fringes 피크의 강도도 증가하였다. 또한, 반사율의 절대값도 $250\~300^{\circ}C$ 사이에서 열처리한 시편에서 가장 높은 값을 나타내었다. 미세구조 분석에 따르면 저온열처리를 통하여 입자크기와 결함량이 줄어들고 결정의 치밀도는 증가하였다.

• 한국세라믹학회지
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• 제46권6호
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• 대한전자공학회논문지SD
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• 제37권4호
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• pp.53-59
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• 2000

광섬유-평면도파로 결합기의 편광선택성을 이용한 새로운 구조의 광섬유형 편광기를 설계 및 제작하였다. 금속클래드-평면도파로의 높은 복굴절을 이용함으로서 동작 파장범위를 증가시킬 수 있었다. 평면도파로의 코어층으로 폴리머를, 클래딩으로 금(Au)을 각각 사용하였다. 실험결과는 평면도파로의 두께를 조절하여 TE편광 혹은 TM 편광이 만들어 질 수 있음을 보인다. 16㏈ 이상의 편광소멸비를 만족하는 파장범위는 130nm 이상으로 나타났고 삽입손실은 0.5㏈ 정도였다.

• 한국전자파학회논문지
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• 제12권5호
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• pp.827-836
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• 2001

L자 형태의 스트립 급전 구조는 두꺼운 유전체 기판 (두께=0.1λ)을 갖는 마이크로 스트립 안테나에 있어 적합한 구조이다. L자 형태의 스트립 급전 구조는 방사 패치와 결합하여 캐패시턴스 성분을 발생시켜 스트립 자체에 의해 발생되는 인덕턴스 성분을 억제시킨다. 본 논문에서는 PCS대역(1,750~1,870 MHz)과 IMT-2000대역(1,920~2,170MHz)의 광대역 주파수(420 MHz)를 모두 만족시킬 수 있는 L자 형태로 급전되는 안테나를 두 개 배열한 형태의 안테나도 소개한다. 이들 두 안테나는 모두 패스밴드에서 안정된 방사패턴을 가지며 임피던스 대역폭은 중심주파수 (1,960 MHz)의 31%(VSWR<1.5, 615 MHz) 이상을 가지고 약 7 dBi의 평균 이득을 갖는다.

• 한국전산유체공학회지
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• 제19권2호
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• pp.99-107
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• 2014

The aim of the present study is to investigate the flow interference between two adjacent undulating fish-like body, and its effect on the undulating propulsion. For this purpose, unsteady two dimensional incompressible flow calculations were conducted using an unstructured mesh flow solver, coupled with an overset mesh technique. To deal with mesh deformation due to fish locomotion, spring analogy is utilized. The fish body used in the simulation is constructed from the NACA0012 airfoil. The study indicates that the propulsion of undulating fish is proportional to frequency and wavelength of the midline oscillation when there is no adjacent fish. It also reveals that average thrust was increased when the vortex shedding from the tail was conserved well and pressure difference between upper and lower sides of the fish was magnified due to flow interference. From this study, which relative position and phase difference of locomotion between two fishes can generate maximum thrust was known among six different cases.

• 대한수의학회지
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• 제41권1호
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• pp.13-19
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• 2001

A simple and rapid analytical method for the determination of tylosin in chicken, pork and muscle was established by High-Performance Liquid Chromatography(HPLC). Chicken, pork and beef muscle(5 g) were fortified by adding the $0.2{\mu}g/ml$ of standard tylosin and the drug was extracted from meats with 70% acetonitrile(ACN) and followed by liquid-liquid partition for clean-up procedure. Then $20{\mu}l$ portion of ACN elution was directly analyzed by HPLC with spectra 100 variable wavelength detector, and unfortified blank control were treated similarly. The average recovery rate of tylosin added to chicken, pork and beef muscle were $83{\pm}2.3$, $96{\pm}3.3$ and $92{\pm}1.6$(%) at the level 0.2 ppm, respectively. No tylosin residues in marketing meats. These results suggested that HPLC methodology could be acceptable for the extraction, determination and screening of tylosin residues in edible meats.