• 한국전산구조공학회논문집
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• 제33권4호
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• pp.255-261
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• 2020

본 논문은 충격을 줄이기 위해 효과적인 충격완충장치를 구성하는 방법을 제안했다. 기존의 충격완충장치는 폴리에틸렌으로만 만들어졌지만, 새로운 충격완충장치는 외측에는 폴리에틸렌, 내측에는 고밀도 재료로 구성하였다. 충격은 내측과 외측 물질 사이의 밀도 차이가 더 클 때 줄어들었다. 2층 구조의 외측으로 설계하기 위해 알루미늄, 티타늄, 구리를 선택하였다. 가장 밀도가 높은 구리에서는 충격 감소가 가장 좋았으며, 기존 충격완충장치보다 최대 감가속도는 43%, 충격량은 51% 감소하였다. 4층, 6층 충격완충장치의 경우, 충격량은 줄였지만, 최대 감가속도는 증가하였다. 신관은 가장 큰 충격으로부터 살아남아야 하며 나머지 충격파는 임계값을 초과하지 않으므로, 본 논문은 폴리에틸렌-구리를 사용한 2층 구조용 충격완충장치를 제안하였다.

• Steel and Composite Structures
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• 제21권2호
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• pp.249-266
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• 2016

The interest of this article lies in the proposition of using bionic method to develop a new sound absorber and analyze the efficient of this absorber in a ski cabin. Inspired by the coupling absorption structure of the skin and feather of a typical silent flying bird - owl, a bionic coupling multi-layer structure model is developed, which is composed of a micro-silt plate, porous fibrous material and a flexible micro-perforated membrane backed with airspace. The finite element simulation method with ACTRAN is applied to calculate the acoustic performance of the multi-layer absorber, the vibration modal of the ski cabin and the sound pressure level (SPL) near the skier's ears before and after pasting the absorber at the flour carpet and seats in the cabin. As expected, the SPL near the ears was significantly reduced after adding sound-absorbing material. Among them, the model 2 and model 5 showed the best sound absorption efficiency and the SPL almost reduced 5 dB. Moreover, it was most effctive for the SPL reduction with full admittance configuration at both the carpet and the seats, and the carpet contribution seems to be predominant.

• 한국인터넷방송통신학회논문지
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• 제20권5호
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• pp.31-37
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• 2020

본 논문에서는 다층구조를 활용한 서브파장 크기의 단위 셀로 구성된 메타물질 흡수체를 제안한다. 제안된 흡수체는 4개 층으로 이루어져 있으며, 각 층에는 비아홀로 연결된 스파이럴 공진기가 위치한다. 이는 단위 셀의 인덕턴스 값을 증가시켜, 공진 주파수를 낮추는 효과를 보인다. 본 논문에서 제안한 구조는 제작을 고려하여 최적화한 결과 단위 셀의 전기적 크기를 파장의 0.013배로 크게 줄일 수 있었다. 제안된 흡수체는 시뮬레이션과 시제품 측정을 통하여 성능을 검증하였다. 측정결과 1.74GHz에서 97% 이상의 흡수율을 확인하였으며, 편파 및 입사각도의 변화에 대해서도 90% 이상의 우수한 흡수율을 확인하였다.

• 한국전기전자재료학회논문지
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• 제27권12호
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• pp.820-824
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• 2014

TiNOx multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. 4 multi-layers of $TiO_2$/TiNOx(LMVF)/TiNOx(HMVF)/Ti/substrate have been prepared with ratio of Ar and ($N_2+O_2$) gas mixture. $TiO_2$ of top layer is anti-reflection layer on double TiNOx(LMVF)/TiNOx(HMVF) layers and Ti metal of infrared reflection layer. In this study, the crystallinity and surface properties of TiNOx thin films were estimated by X-ray diffraction(XRD) and field emission scanning electron microscopy(FE-SEM), respectively. The grain size of TiNOx thin films shows to increase with increasing sputtering power. The composition of thin films has been investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The TiNOx multi-layer films show the excellent optical performance beyond 9% of reflectance in those ranges wavelength.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.666-666
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• 2013

CIGS solar cell에서 p-type semiconductor역할을 수행하는 Cu(In,Ga)Se로 이루어진 Absorber layer는 4 element multi binary compound로 stoichiometry 측면에서 다양한 형태가 나타나기 때문에 태양전지 효율을 향상시키기 위해 이에 대한 연구가 활발하다. 우리는 E-beam evaporation 방법으로 다양한 조건의 multi layer로 증착된 CIG layer 위에 일정 두께의 Se을 증착하면서 열처리 조건에 따른 Selenization 메커니즘에 대한 연구를 수행하였다. 결과분석을 위해(in-situ High Temperature) XRD, XPS, Micro Raman spectroscopy, FE-SEM, (Nano Indentor, Atomic Force Microscopy) 등을 이용하여 결정구조, 결정화도, Depth profile, Eg (band gap energy) 등을 알아보고 분석결과간의 상관관계를 고찰하였다.

• Transactions on Electrical and Electronic Materials
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• 제17권3호
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• pp.146-149
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• 2016

The CrN/TiN/Al thin films for solar selective absorber were prepared by dc reactive magnetron sputtering with multi targets. The binary nitride CrN layer deposited with change in N₂ gas flow rates. The gas mixture of Ar and N2 was an important parameter during sputtering deposition because the metal volume fraction (MVF) was controlled by the N2 gas flow rate. In this study, the crystallinity and surface properties of the CrN/TiN/Al thin films were estimated by X-ray diffraction (XRD), atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The composition and depth profile of thin films were investigated using Auger electron spectroscopy (AES). The absorptance and reflectance with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 300~1,100 nm.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.322.1-322.1
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• 2014

Many research groups have studied tandem or multi-junction cells to overcome this low efficiency and degradation. In multi-junction cells, band-gap engineering of each absorb layer is needed to absorb the light at various wavelengths efficiently. Various absorption layers can be formed using multi-junctions, such as hydrogenated amorphous silicon carbide (a-SiC:H), amorphous silicon germanium (a-SiGe:H) and microcrystalline silicon (${\mu}c$-Si:H), etc. Among them, ${\mu}c$-Si:H is the bottom absorber material because it has a low band-gap and does not exhibit light-induced degradation like amorphous silicon. Nevertheless, ${\mu}c$-Si:H requires a much thicker material (>2 mm) to absorb sufficient light due to its smaller light absorption coefficient, highlighting the need for a high growth rate for productivity. ${\mu}c$-SiGe:H has a much higher absorption coefficient than ${\mu}c$-Si:H at the low energy wavelength, meaning that the thickness of the absorption layer can be decreased to less than half that of ${\mu}c$-Si:H. ${\mu}c$-SiGe:H films were prepared using 40 MHz very high frequency PECVD method at 1 Torr. SiH4 and GeH4 were used as a reactive gas and H2 was used as a dilution gas. In this study, the ${\mu}c$-SiGe:H layer for triple solar cells applications was performed to optimize the film properties.

• 한국음향학회지
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• 제28권8호
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• pp.806-814
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• 2009

이 논문은 능동흡음재를 이용한 수중음향반사파 상쇄에 관한 연구이다. 능동흡음재는 평판형 구동센서와 수신센서로 몰딩되고 외부 제어기와 연결된 구조로 되어있다. 이 두 층의 센서와 피드백제어기는 하나의 피드백 루프를 이루며, 이 루프의 특징은 외부로부터 인가되는 입사파에 대해 음향 임피던스가 자동적으로 정합되어, 자동적으로 반사파를 상쇄하는 특성을 가진다. 능동흡음재의 전기 구조 음향의 다중물리특성은 1차원 전달함수로 모델링 되고, 운용주파수 대역에서 입사파에 대한 반사파가 최소화 되도록 제어기의 전달함수가 설정된다. 능동형 흡음재는 수동형 흡음재의 두께에 비하여 현저히 얇은 두께를 가지며, 간단한 아날로그 회로 제어기만으로도 넓은 주파수 대역에서 우수한 흡음특성을 보인다.

• 한국전기전자재료학회논문지
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• 제27권9호
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• pp.589-593
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• 2014

AlNO multi-layer thin films on aluminum substrates were prepared by DC reactive magnetron sputtering method. $Al_2O_3$/AlNO(LMVF)/AlNO(HMVF)/Al/substrate of 4 multi-layer has been prepared in an Ar and ($N_2+O_2$) gas mixture, and $Al_2O_3$ of top layer is anti-reflection layer on double AlNO(LMVF)/AlNO(HMVF) layers and Al metal of infrared reflection layer. In this study, the roughness and surface properties of AlNO thin films were estimated by field emission scanning electron microscopy(FE-SEM). The grain size of AlNO thin films increased with increasing sputtering power. The composition of thin films has been systematically investigated using electron probe microanalysis(EPMA). The optical properties with wavelength spectrum were recorded by UV-Vis-NIR spectrophotometry at a range of 200~1,500 nm. The absorptance of AlNO films shows the increasing trend with swelling ($N_2+O_2$) gas mixture in HMVF and LMVF deposition. The excellent optical performance showed above 98% of absorptance in visible wavelength region.

• 한국표면공학회지
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• 제48권4호
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• pp.169-173
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• 2015

$CuInSe_2$ thin films which have been widely used for thin solar cells as a light absorber were prepared by hydrazine solution processing, and their microstructural properties were investigated. Hydrazine $CuInSe_2$ precursor solutions were prepared by dissolving $Cu_2S$, S, $In_2Se_3$ and Se powder in hydrazine solvent. Multilayer $CuInSe_2$ chalcopyrite phase thin films were prepared by repeating spin-coating process using the precursor solution. Unfortunately, the presence of the interfaces between each $CuInSe_2$ layer formed by multi-layer coating impeded grain growth across the interface. Here, by doing simple interface engineering to solve the limited grain growth issue, the large grained (${\sim}1{\mu}m$) $CuInSe_2$ thin films were obtained.