• 에너지공학
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• 제5권2호
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• pp.108-114
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• 1996

태양열 집열판의 효율을 증대시키기 위하여는 집열판에 조사되는 태양광의 흡수율을 높이고 복사에 의한 열손실을 감소시키는 선택적 박막을 집열판에 입히는 것이 중요한 인자이다. 본 실험에서는 이와같은 광학적 특성을 지니게 하고 동시에 전류효율이 우수한 pulsecurrent 전해법을 도입하여 실제 실용화 규모인 230 cm$\times$60 크기의 대형 기판에 선택흡수박막의 전착을 실시하였다. 도금액의 조성은 크롬산 280 g/$\ell$, propionic acid 15g/$\ell$, 그리고 제 2첨가제10g/$\ell$이었으며, 도금 대상기판으로는 구리와 알루미늄이 사용되었다. 구리 기판의 경우에는 선택흡수박막의 흡수율이 약 0.98이고 복사율은 약 0.17의 광학적 성질을 보였으며, 30$0^{\circ}C$공기 중에서 24시간동안 열처리 후에도 광학적 우수성을 지니고 있어 상품적 가치가 매우 우수하다고 판단되었다. 알루미늄 기판의 경우에는 흡수율이 약 0.97, 복사율이 0.15로서 광학적 성질은 구리 기판에 비해 다소 떨어지지만, 열전도도와 경제성을 고려하면 상품적 가치가 충분하다고 생각된다. 또한 이와 같은 대형기판을 적용하여 안정된 태양광 선택흡수박막의 성공적 제조로 공정의 단순화 및 대량생산 기술을 확보하였으며, 상용화에 돌입하게 되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.121-121
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• 2010

ZnO is a promising material for the application of high efficiency light emitting diodes with short wavelength region for its large bandgap energy of 3.37 eV which is similar to GaN (3.39 eV) at room temperature. The large exciton binding energy of 60 meV in ZnO provide provides higher efficiency of emission for optoelectronic device applications. Several ZnO/ZnMgO multiple quantum well (MQW) structures have been grown on various substrates such as sapphire, GaN, Si, and so on. However, the achievement of high quality ZnO/ZnMgO MQW structures has been somehow limited by the use of lattice-mismatched substrates. Therefore, we propose the optical properties of ZnO/ZnMgO multiple quantum well (MQW) structures with different well widths grown on lattice-matched ZnO substrates by molecular beam epitaxy. Photoluminescence (PL) spectra show MQW emissions at 3.387 and 3.369 eV for the ZnO/ZnMgO MQW samples with well widths of 2 and 5 nm, respectively, due to the quantum confinement effect. Time-resolved PL results show an efficient photo-generated carrier transfer from the barrier to the MQWs, which leads to an increased intensity ratio of the well to barrier emissions for the ZnO/ZnMgO MQW sample with the wider width. From the power-dependent PL spectra, we observed no PL peak shift of MQW emission in both samples, indicating a negligible built-in electric field effect in the ZnO/$Zn_{0.9}Mg_{0.1}O$ MQWs grown on lattice-matched ZnO substrates.

• 폴리머
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• 제39권3호
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• pp.514-521
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• 2015

본 연구는 자동차, 건축, 디스플레이 부품 접합 등에 사용되는 다층구조형 양면 점착테이프에 대한 것으로 UV 경화에 의해 제조된 아크릴폼 기재에 용제 건조형 점착제(AD)를 양면에 붙이고 피착제 종류에 따른 박리강도와 전단접착강도를 고찰하였다. AD 종류와 기재 조성에 따른 접착력 변화 및 피착재로 사용한 플라스틱에 대한 접착력을 고찰한 결과, AD의 분자량(MW)이 증가할수록 박리강도 및 전단접착강도가 증가하였으나 약 65만 이상의 MW를 가진 AD는 접착력이 감소하는 거동을 보였다. 양면 점착테이프에 사용된 AD층 두께가 얇을수록 온도감소와 함께 높은 물성 값을 보였다. 기재와 AD와의 계면접합 특성은 MW 615000(AD-4)을 사용한 것이 가장 우수하였으며, MW가 615000보다 낮으면 기재인 아크릴 폼과의 계면이 분리되는 결과를 보였다. 따라서 본 연구에서 검토한 다층구조형 양면 점착테이프는 표면에너지가 낮은 플라스틱 부품 및 곡면 부위에 적용가능한 산업분야에 유용하게 사용될 수 있을 것으로 판단된다.

• Current Photovoltaic Research
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• 제2권3호
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• pp.95-102
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• 2014

Light trapping techniques can change the propagation direction of incident light and keep the light longer in the absorption layers of solar cells to enhance the power conversion efficiency. In thin film silicon (Si) solar cells, the thickness of absorption layer is generally not enough to absorb entire available photons because of short carrier life time, and light induced degradation effect, which can be compensated by the light trapping techniques. These techniques have been adopted as textured transparent conduction oxide (TCO) layers randomly or periodically textured, intermediate reflection layers of tandem and triple junction, and glass substrates etched by various patterning methods. We reviewed the light trapping techniques for thin film Si solar cells and mainly focused on the commercially available techniques applicable to textured TCO on patterned glass substrates. We described the characterization methods representing the light trapping effects, texturing of TCO and showed the results of multi-scale textured TCO on etched glass substrates. These methods can be used tandem and triple thin film Si solar cells to enhance photo-current and power conversion efficiency of long term stability.

• 한국환경농학회지
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• 제41권2호
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• pp.71-81
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• 2022

BACKGROUND: Animal manures are one of the biggest sources of greenhouse gases and improper manage-ment of animal wastes contributes to the increasing greenhouse gases in the atmosphere. Con-verting greenhouse gases generated from animal manures to energy is one way of contributing to the net-zero carbon emissions. METHODS AND RESULTS: The potential for methane production from cow manure (CM) was studied by measuring the methane yield using the biochemical methane potential (BMP) test. In particular, the effect of co-digestion using rice straw (RM) on the methane production was studied. The methane yields from the co-digestion of CM and RS were statistically similar to that from the mono-digestion of CM or RS. But there was a synergy effect at the CM:RS ratio of 1:2 and 1:1. This can be attributed to the increased C/N ratio. The changed microbial community structure with the addition of substrates (CM, RS) probably led to the increase in the methane produc-tion. CONCLUSION(S): The methane production potential of the particular CM used in this study was not improved by the addition of RS as a co-substrate. The addition of substrates to the anaerobic sludge promoted the increase in the microbial species having synergetic relationship with methano-gens, and this can partially explain the increase in the methane production with the addition of substrates. Overall, there are needs for further studies to improve the methane yield from CM.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.342-346
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• 2004

Recently there has been a great world-wide interest in developing and characterizing new nano-structured materials. These newly developed materials are often prepared in limited quantities and shapes unsuitable for the extensive mechanical testing. The development of depth sensing indentation methods have introduced the advantage of load and depth measurement during the indentation cycle. In the present work, ZnO thin films are prepared on the Glass, GaAs(100), Si(111), and Si(100) substrates at different temperatures by pulsed laser deposition(PLD) method. Because the potential energy in c-axis is law, the films always shaw c-axis orientation at the optimized conditions in spite of the different substrates. Thin films are investigated by X-ray diffractometer and Nano indentation equipment. From these measurements it is possible to get elastic modulus and hardness of ZnO thin films on all substrates.

• BMB Reports
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• 제33권4호
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• pp.312-316
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• 2000

Effects of various nitrogenous compounds on the peroxidative activity of Korean radish (Rophanus sativus L.) isoperoxidase $A_1$ were examined by using anilino substrates, such as dianisidine and phenylenediamine. We also used phenolic substrates such as guaiacol, chlorogenic acid, caffeic acid, ferulic acid and esculetin. The peroxidation of dianisidine was stimulated by adenine and imidazole as much as 5 fold and 11 fold, respectively at pH 8. Moreover, about 4.8 fold and 8 fold stimulation of phenylenediamine peroxidation occurred by adenine and imidazole, respectively at pH 8. The stimulation by adenine and imidazole did not occur at the acidic pH range. The peroxidations of phenolic substrates, such as guaiacol, chlorogenic acid, caffeic acid, ferulic acid and esculetin, were not boosted greatly by any of the nitrogenous compounds tested. Notably, ammonium salt, which has been known for the excellent booster of horseradish peroxidase, did not affect the peroxidation of the Korean radish isoperoxidase $A_1$. The kinetic studies of dianisidine peroxidation with imidazole, as a model of boosting reaction, showed that neither the affinity of imidazole against dianisidine, nor the activation energy of dianisidine peroxidation changed during the activity boosting of isoperoxidase $A_1$.

• 한국진공학회지
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• 제12권3호
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• pp.182-192
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• 2003

밀리미터파 대역용 고속 PHEMT 소자 제작 및 개발을 위하여 다층 리지스트 및 다원자 기판 구조에서 전자빔 리소그래피 공정을 분석할 수 있는 새로운 몬테 카를로 시뮬레이션 모델을 개발하였다. 전자빔에 의해 다층 다원자 타겟 기판 구조에 전이되는 에너지를 정확하고 효율적으로 계산하기 위하여 다층 리지스트 및 다층 다원자 기판 구조에서 시뮬레이션 가능하도록 새로이 모델링하였다. 본 논문에서 제안 개발된 모델을 사용하여 PHEMT 소자의 전자빔 리소그래피에 의한 T-게이트 형성 공정을 시뮬레이션하고 SEM측정 결과와 비교 분석하여 타당성을 검증하였다.

• 상하수도학회지
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• 제17권4호
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• pp.550-558
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• 2003

Digestion of primary sludge was conducted to evaluate the effects of reactor configuration using UAD, CUAD, TPAD, and semi-continuos CSTR. Highest VSS reduction and gas production were obtained in CUAD at all HRT. More efficient digestion was accomplished in upflow digesters compared to TPAD and CSTR. Higher thickening of solids in reactor and longer solids retention were main reasons for the enhanced digestion in CUAD and UAD. Performance based on the SRT of CUAD was nearly identical to that of UAD. However, those of TPAD and CSTR were lower than that of CUAD. Particulate and soluble organics in upflow reactors were well adsorbed due to secreted extracellular polymeric substances from the sludge granules. These might result in close proximity of microorganisms and substrates and enhanced hydrolysis. Additionally, diverse anaerobic microorganisms and neutral pH in upflow reactor could induce more activity of hydrolytic enzymes and sludge granules might offer lower thermodynamic energy state. While, excessive mixing in CSTR could break conglomerates of enzymes and substrates into fine particles, which resulted in lowered hydrolysis. Low pH level in acid fermenter of TPAD lowered hydrolysis of the particulate substrates.

• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.828-833
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• 2000

Growth characteristics and microstructure of AIN thin films grown by plasma assisted molecular beam epitaxy on Si substrates have been investigated. Growing temperature and substrate orientation were chosen as major variables of the experiment. Reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy/diffraction (TEM/TED) techniques were employed to characterize the micorstructure of the films. On Si(100) substrates, AlN thin films were grown along the hexagonal c-axis preferred orientation at temperature range 850-90$0^{\circ}C$. However on Si(111), the AlN films were epitaxially grown with directional coherency in AlN(0001)/Si(111), AlN(1100)/Si(110), and AlN(1120)/Si(112) at 85$0^{\circ}C$ and the epitaxial coherencry seemed to be slightly distorted with increasing temperature. The microstructure of AlN thin films on Si(111) substrates showed that the films include a lot of crystal defects and there exist micro-gaps among the columns.