• 제목/요약/키워드: Stabilized efficiency

검색결과 190건 처리시간 0.024초

고 안정화 프로터결정 실리콘 다층막 태양전지 (Highly Stabilized Protocrystalline Silicon Multilayer Solar Cells)

  • 임굉수;곽중환;권성원;명승엽
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2005년도 춘계학술대회
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    • pp.102-108
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    • 2005
  • We have developed highly stabilized (p-i-n)-type protocrystalline silicon (pc-Si:H) multilayer solar cells. To achieve a high conversion efficiency, we applied a double-layer p-type amorphous silicon-carbon alloy $(p-a-Si_{1-x}C_x:H)$ structure to the pc-Si:H multilayer solar cells. The less pronounced initial short wavelength quantum efficiency variation as a function of bias voltage proves that the double $(p-a-Si_{1-x}C_x:H)$ layer structure successfully reduces recombination at the p/i interface. It was found that a natural hydrogen treatment involving an etch of the defective undiluted p-a-SiC:H window layer before the hydrogen-diluted p-a-SiC:H buffer layer deposition and an improvement of the order in the window layer. Thus, we achieved a highly stabilized efficiency of $9.0\%$ without any back reflector.

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폐기물매립지 차수재로서 고화토의 중금속 고정능력 평가에 관한 연구 (A Study on the Fixation of Heavy Metals with Stabilized Soils in the Landfill Liner)

  • 노희정;이재영
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2000년도 추계학술대회
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    • pp.145-149
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    • 2000
  • We performed the geotechnical experiments of the hydraulic conductivity and compressive strength test with the stabilized soil in the laboratory, proved that it is useful to use the stabilized soil as an alternative for natural clay soil. Also, for mixing adding materials in the stabilized soil, it was determined that 1) the optimal mixing ratio of cement : bentonite : stabilizing agent was 90:60:1 of mass ratio(kg) for 1㎥ with soil, 2) it was also possible to use low quality bentonite(B\circled2) classified by swelling grade because of little difference from results of the hydraulic conductivity and compressive strength test with high quality bentonite(B\circled1). According to the results of the fixation ability of heavy metals(Pb$^{2+}$, Cu$^{2+}$, Cd$^{2+}$, Zn$^{2+}$) with soil and additives, authors can conclude that the higher pH condition had the more removal efficiency of heavy metals. B\circled1 and cement had especially high removal efficiency of heavy metals in a whole pH because of high alkalinity.alinity.

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COMPARISON OF DIFFERENT NUMERICAL SCHEMES FOR THE CAHN-HILLIARD EQUATION

  • Lee, Seunggyu;Lee, Chaeyoung;Lee, Hyun Geun;Kim, Junseok
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • 제17권3호
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    • pp.197-207
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    • 2013
  • The Cahn-Hilliard equation was proposed as a phenomenological model for describing the process of phase separation of a binary alloy. The equation has been applied to many physical applications such as amorphological instability caused by elastic non-equilibrium, image inpainting, two- and three-phase fluid flow, phase separation, flow visualization and the formation of the quantum dots. To solve the Cahn-Hillard equation, many numerical methods have been proposed such as the explicit Euler's, the implicit Euler's, the Crank-Nicolson, the semi-implicit Euler's, the linearly stabilized splitting and the non-linearly stabilized splitting schemes. In this paper, we investigate each scheme in finite-difference schemes by comparing their performances, especially stability and efficiency. Except the explicit Euler's method, we use the fast solver which is called a multigrid method. Our numerical investigation shows that the linearly stabilized stabilized splitting scheme is not unconditionally gradient stable in time unlike the known result. And the Crank-Nicolson scheme is accurate but unstable in time, whereas the non-linearly stabilized splitting scheme has advantage over other schemes on the time step restriction.

입체 구조적으로 안정화된 리포좀의 동결건조에 따른 물리적 특성 (Physical Characteristics of Sterically Stabilized Liposomes after Lyophilization and Rehydration)

  • 전호성;이상길;최영욱
    • Journal of Pharmaceutical Investigation
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    • 제31권1호
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    • pp.43-47
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    • 2001
  • Sterically stabilized liposomes (SSL) have been introduced for longer circulation in blood than conventional liposomes (CL). However, there are a couple of problems in SSL preparation due to the instability of phospholipid and the degradation of drug in aqueous conditions. To solve these problems, it is necessary to go through lyophilization process. Therefore, in this study, effects of lyophilization on SSL were evaluated for physical characteristics changes upon rehydration of lyophilized SSL such as the particle size, efficiency of drug entrapment, turbidity and drug release. SSL containing streptozocin, a water-soluble anticancer drug as a model compound, were prepared with DSPC and DSPE-PEG 2000. The size was controlled to 100 nm by extrusion with polycarbonate membrane, and sucrose was used as a cryoprotectant for lyophilization at the 1:3 (lipid:sucrose) ratio. Upon rehydration of lyophilized SSL, the average size was in the range of $50{\sim}200\;nm$ which is adequate for longer circulation in blood, and the encapsulation efficiency was kept as its initial state. Rehydrated SSL were not adsorbed to rat plasma protein and revealed a similar drug release profile to that of fresh SSL before lyophilization. Therefore, lyophilization could be introduced efficiently to overcome aqueous instability problems of SSL.

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리포좀 제제 중 렉틴-엘라지탄닌 포합체의 분석법 확립 (Assay Method for Lectin-conjugated Ellagitannin Encapsulated in Liposomal Formulations)

  • 전현주;최영욱
    • Journal of Pharmaceutical Investigation
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    • 제31권3호
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    • pp.197-200
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    • 2001
  • Lectin-conjugated ellagitannin (LET), a newly introduced melanoma-specific antitumor agent which has been synthesized by conjugation of wheat germ agglutinin as a lectin with praecoxin A as an ellagitannin, was encapsulated into sterically stabilized liposomes (SSL). Modified Folin phenol method was established for the quantitation of LET contents in liposomal formulations protein employing the standard calibration curve with bovine serum albumin. After removal of phospholipid by organic solvent extraction, which interferes the specific selectivity of the Folin-Ciocalteu reagent with the protein, recovery of LET was $94.5{\pm}2.3%$ and the encapsulation efficiency was revealed as $37.8{\pm}5.9%$ for 2.5 mg/ml LET solution.

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석회석을 활용한 광미와 폐석의 Cd, Cu, Pb 및 Zn의 제거

  • 지한구;정명채;정문영;최연왕;이문현;이재영
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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    • pp.20-23
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    • 2005
  • The objective of this study is to examine a stabilized efficiency of heavy metals including Cd, Cu, Pb and Zn using slaked lime. Tailings from the Janggun Pb-Zn mine, the second Yeonhwa Pb-Zn mine, the Jisi Au-Ag mine and the Sangdong W mine were sampled and measured heavy metal concentrations contents using AAS as various extraction methods. During 156 hours, column test were undertaken to evaluate the possibility of stabilization by slaked lime. The result shows that $Ca(OH)_2$ has a good efficiency in heavy metal stabilization, especially at the Jisi mine with stabilized efficiencies of 97%(Cd), 99%(Cu), 86%(Pb) and 99%(Zn), respectively.

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Efficient Meshfree Analysis Using Stabilized Conforming Nodal Integration for Metal Forming Simulation

  • Han, Kyu-Taek
    • Journal of Advanced Marine Engineering and Technology
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    • 제34권7호
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    • pp.943-950
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    • 2010
  • An efficient meshfree method based on a stabilized conforming nodal integration method is developed for elastoplastic contact analysis of metal forming processes. In this approach, strain smoothing stabilization is introduced to eliminate spatial instability in Galerkin meshfree methods when the weak form is integrated by a nodal integration. The gradient matrix associated with strain smoothing satisfies the integration constraint for linear exactness in the Galerkin approximation. Strain smoothing formulation and numerical procedures for path-dependent problems are introduced. Applications of metal forming analysis are presented, from which the computational efficiency has been improved significantly without loss of accuracy.

정수처리에서 생물학적 망간처리 (Biological Manganese Removal in Water Treatment)

  • 김범수;윤재경;안효원;김충환
    • 상하수도학회지
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    • 제20권1호
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    • pp.44-52
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    • 2006
  • Bio-filtration processes using honeycomb tubes (process 1) and aeration and manganese-sand filtration (process 2) were evaluated for the biological manganese removal efficiency. The concentration of manganese at effluent was stabilized after 20days operation in process 1. It was estimated the required time for attaching and growing microorganisms to honeycomb tubes. In long term of operation periods, manganese removal efficiency was dropped for the excessively attached biofilm and manganese dioxide to honeycomb tubes. It took several days for normal operation in process 2, after that manganese removal efficiency was increased to 98% and stabilized for 1.5 years. Microorganisms in process 1 and 2 were isolated and cultured to characterize manganese-oxidizing bacteria. Among the four types of colony, light brown colony was turned blue color by leuco crystal violet spot test. Stenotropomonas genus, known as manganese-oxidizing bacteria, was identified by 16S rDNA partial sequencing analysis which was isolated in process 1 and 2. For the biological treatment to remove manganese, these two considerations are important. One is to choose the proper media attaching manganese oxidant, another one is to define the cultural condition of isolated manganese-oxidizing bacteria.

공기공급량과 계란 껍질 첨가가 유기성 폐수슬러지 액비 비효효과에 미치는 영향 (Effects of Air Supply Rate and Eggshell Addition on Liquid Fertilizer Efficiency of Aerobic Stabilized Organic Wastewater Sludge)

  • 천효창;황응주;김상현
    • 대한환경공학회지
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    • 제33권8호
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    • pp.578-582
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    • 2011
  • 호기성 소화를 통해 안정화된 유기성 슬러지는 질소 비료로서 활용될 수 있는 잠재력이 있다. 본 연구에서는 식품공장 폐수 처리장에서 발생한 슬러지를 호기성 소화한 후, 소화액의 비효효과를 오이 생장을 통해 평가하였다. 공기 공급량을 200 mL/L/min까지 증가시킬 경우, 질산화와 비효효과가 향상됨을 확인하였다. 또한 일반 비료에 비해 슬러지 내 함유량이 부족한 칼륨 등을 보충하기 위해 음식물 쓰레기의 일종인 계란 껍질 가루를 시비 시 함께 투여하여, 식물 생장이 향상됨을 확인하였다. 본 논문에서 제시하는 적정 공기 공급량과 저가의 첨가제 투여는 슬러지 액비의 품질을 보장하는데 활용될 수 있을 것으로 사료된다.

나노입자기반 CO2 폼을 이용한 CO2 지중저장에 대한 기술적 고찰 (Review of the CO2 Geological Storage Using Nanoparticle-stabilized CO2 Foam)

  • 손한암
    • 자원환경지질
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    • 제53권2호
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    • pp.213-220
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    • 2020
  • 이산화탄소(CO2)를 대염수층에 폼 상태로 주입할 경우 그대로 주입했을 때보다 CO2의 상대투과도가 감소하고 점성도가 증가하여 유동도가 감소한다. 이로 인해 대염수층과의 CO2와의 접촉효율이 증가하면서 궁극적으로 CO2 저장효율이 향상된다. 일반적으로 CO2 폼 형성을 위해서 계면활성제를 사용하였는데, 최근에는 계면활성제만을 사용했을 때보다 안정적인 폼 형성을 위해서 나노입자를 이용한 연구가 많이 수행되고 있다. 이 논문에서는 나노입자 기반 CO2 폼을 이용한 CO2 저장기술에 대해서 소개하였다. 친수성 나노입자의 일부표면을 CO2 친화적인 부분으로 개질하면 입자는 CO2와 물에 양친성을 나타내므로 고온, 고염도 조건의 심부 대염수층에서도 폼은 상대적으로 안정적인 상태를 유지할 수 있다. 경제적인 측면에서 나노기반 CO2 폼 주입공법은 일반적인 CO2 주입보다 비용이 증가하지만 주입 효율성이 향상되므로 가격 경쟁력이 있을 것으로 추정된다. 환경적 측면에서 살펴보자면 세계적으로 오염물질 제거, 석유생산 등 특수한 목적을 위해 대수층이나 저류층에 계면활성제나 나노물질 등의 화학물질 주입이 가능한 상황이다. 그러나 일부 연구에 의하면 나노입자나 계면활성제에는 수생동물에 영향을 줄 수 있는 독성이 있는 것으로 알려져 있기에 환경적 검증된 물질을 사용해야 할 것이다. 따라서 향후에도 추가적인 연구개발을 통해 환경적으로도 안전하면서도 경제적으로도 합리적인 나노기반 CO2 폼 제조 및 주입에 대한 연구가 필요할 것이다.