• 환경위생공학
• /
• 제13권3호
• /
• pp.9-18
• /
• 1998

An experimental research was conducted to establish primary data for the stabilization assessment of industrial wastes landfill with analysis of waste components and investigation of leachate and gas generation, using three sets of lysimeter as experimental apparatus. Comparing results of lysimeter from data of landfill, it is suggested that lysimeter of this study can be used to accomplish the stabilization assessment of the real landfill site. Moisture content was lower as landfill period was older and combustible component was the highest in lysimeter C. The C/N ratio of waste was 7.4~14.4 and, with the elemental analysis, the theoretical gas generation rate based on the modified Buswell equation was 0.47~0.49 $m^3/kg-dry$ waste in lysimeter C. Considering the C/N ratio of leachate, it is concluded that the addition of carbon source is needed to biodegrade leachate hereafter. Gas generation rate($m^3/kg-dry$ waste) from lysimeter A, B and C was 0.0009, 0.014 and 0.0067, respectively, and different from each other according to the landfill period of wastes. The results in this study show that the biodegradation of microorganism for stabilization of landfill was inhibited and more activated in acidogenic step than in methanogenic of anaerobic degradation.

• 한국수소및신에너지학회논문집
• /
• 제32권5호
• /
• pp.285-292
• /
• 2021

To study the effect of the mixture ratio of Ni-Pt nanocatalysts on water electrolysis characteristics in anion exchange membrane system, Ni-Pt nanocatalysts were loaded on carbon black by using a spontaneous reduction reaction of acetylacetonate compounds. The loading weight of Ni-Pt nanocatalysts on the carbon black was measured by thermogravimetric analyzer and the elemental ratio of Ni and Pt was estimated by energy dispersive x-ray analyzer. It was found that the loading weight of Ni-Pt nanoparticles was 5.36-5.95 wt%, and the loading weight increased with increasing Pt wt%. As the Ni-Pt loading weight increased, the specific surface area decreased, because Ni-Pt nanoparticles block the pores of carbon black. It was confirmed by BET analysis and dynamic vapor sorption analysis. I-V characteristics were estimated.

• Current Photovoltaic Research
• /
• 제7권4호
• /
• pp.103-110
• /
• 2019

Cu(In,Ga)₃Se₅ (β-CIGS) has a band gap of 1.35 eV, which is an optimum value for high solar-energy conversion efficiency. The effects of Cu and Ga content on the cell performance were investigated previously. However, the effect of Se content on the cell performance is not well understood yet. In this work, β-CIGS films were fabricated by three-stage co-evaporation of elemental sources with various Se fluxes at the third stage instead of at all stages. The average composition of five samples was Cu_1.05(In_0.59,Ga_0.41)3Se_y, where the stoichiometric y value is 5.03 and the stoichiometric Se/metal (Se/M) ratio is 1.24. We varied the Se/metal ratio in a range from 1.18 to 1.28. We found that the best efficiency was achieved when the Se/M ratio was 1.24, which is exactly the stoichiometric value where the CIGS grains on the CIGS surface were tightly connected and faceted. With the optimum Se/M ratio, we were able to enhance the cell efficiency of a β-CIGS solar cell from 9.6% to 12.0% by employing a Na₂S post deposition treatment. Our results indicate that Na₂S post deposition treatment is very effective to enhance the cell efficiency to a level on par with that in α-CIGS cell.

• Smart Structures and Systems
• /
• 제23권2호
• /
• pp.107-122
• /
• 2019

As one of the most important parameters in structural health monitoring, structural frequency has many advantages, such as convenient to be measured, high precision, and insensitive to noise. In addition, frequency-change-ratio based method had been validated to have the ability to identify the damage occurrence and location. However, building a precise enough finite elemental model (FEM) for the test structure is still a huge challenge for this frequency-change-ratio based damage detection technique. In order to overcome this disadvantage and extend the application for frequencies in structural health monitoring area, a novel method was developed in this paper by combining the cross-model cross-mode (CMCM) model updating algorithm with the frequency-change-ratio based method. At first, assuming the physical parameters, including the element mass and stiffness, of the test structure had been known with a certain value, then an initial to-be-updated model with these assumed parameters was constructed according to the typical mass and stiffness distribution characteristic of shear buildings. After that, this to-be-updated model was updated using CMCM algorithm by combining with the measured frequencies of the actual structure when no damage was introduced. Thus, this updated model was regarded as a representation of the FEM model of actual structure, because their modal information were almost the same. Finally, based on this updated model, the frequency-change-ratio based method can be further proceed to realize the damage detection and localization. In order to verify the effectiveness of the developed method, a four-level shear building was numerically simulated and two actual shear structures, including a three-level shear model and an eight-story frame, were experimentally test in laboratory, and all the test results demonstrate that the developed method can identify the structural damage occurrence and location effectively, even only very limited modal frequencies of the test structure were provided.

• 공업화학
• /
• 제10권8호
• /
• pp.1129-1135
• /
• 1999

${\gamma}-Al_2O_3$, $TiO_2$와 $SiO_2$에 코발트를 함침시켜 촉매를 제조하고, 고정층 미분반응기에서 CO에 의한 $SO_2$환원반응 특성을 조사하였다. 이때 온도는 $350{\sim}550^{\circ}C$ 영역에서, $SO_2$농도를 1000~10000 ppm, $CO/SO_2$몰비를 1.0~3.0, 공간속도를 $5000{\sim}15000h^{-1}$의 영역에서 사용하였으며 대기압하에서 실행하였다. ${\gamma}-Al_2O_3$와 $TiO_2$는 코발트 담체로 우수한 특성을 보였으며, 5 wt % 코발트를 ${\gamma}-Al_2O_3$에 함침시켜 얻은 촉매로 $400^{\circ}C$ 이상의 온도에서 90% 이상의 높은 $SO_2$전환율과 6% 이하의 낮은 COS수율을 얻을 수 있었다. $CO/SO_2$의 최적몰비는 양론비인 2.0으로 나타났으며, 몰비가 3.0으로 증가하면 $SO_2$전환율은 증가하였으나 대부분의 반응생성물이 COS로 나타났다. 실험영역의 $SO_2$농도와 공간속도의 변화는 $SO_2$ 전환율과 반응선택성에 큰 영향을 미치지 않았다. 코발트는 활성화된 이후에 $CoS_2$ 상태로 존재하였으며 반응후에도 상변화는 관찰되지 않았다.

• 대한화학회지
• /
• 제59권3호
• /
• pp.215-224
• /
• 2015

Unsymmetrical tetradentate Schiff base N-(2-hydroxy-5-methylacetophenone)-N'-(2-hydroxy acetophenone) ethylene diamine (H₂L) and its complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) have been synthesized and characterized by elemental analyses, magnetic susceptibility measurements, IR, electronic spectra and thermogravimetric analyses. ¹H, ¹³C-NMR and FAB Mass spectra of ligand clearly indicate the presence of OH and azomethine groups. Elemental analyses of the complexes indicate that the metal to ligand ratio is 1:1 in all complexes. Infrared spectra of complexes indicate a dibasic quadridentate nature of the ligand and its coordination to metal ions through phenolic oxygen and azomethine nitrogen atoms. The thermal behavior of these complexes showed the loss of lattice water in the first step followed by decomposition of the ligand in subsequent steps. The thermal data have also been analyzed for the kinetic parameters by using Horowitz-Metzger method. The dependence of the electrical conductivity on the temperature has been studied over the temperature range 313-403 K and the complexes are found to show semiconducting behavior. XRD and SEM images of some representative complexes have been recorded. The antimicrobial activity of the ligand and its complexes has been screened against various microorganisms and all of them were found to be active against the test organisms. The Fe(III) and Ni(II) complex have been tested for the catalytic oxidation of styrene.

• 문화기술의 융합
• /
• 제4권2호
• /
• pp.211-216
• /
• 2018

흡착과 막을 융합시킨 분리기술은 수처리와 같은 환경 분야에서 많은 응용이 기대된다. 이 융합기술에 막분리 공정에서 문제가 되는 막 fouling을 억제시키기 위해 막표면에 카본휘스커를 성장시킨 기능성 카본막을 개발하였다. 본 연구에서는 기능성 카본막의 제조 Mechanism을 밝히기 위해, 각각의 혼합비율인 폴리머라텍스로 전처리를 하고 CVD(Chemical Vapor Deposing)법에 따라 막을 제조하였다. 이 막을 주사전자현미경(Scanning Electron Microscope(SEM)), CHN분석기(Elemental Analyzer), X-선회절법(X-Ray Diffraction(XRD))으로 분석하였다. 그 결과 3번막(PVdC(PolyVinyl di-Chloride):PVC(Polyvinly Chloride)=4.5:55)의 경우가 카본휘스커의 직경과 밀도가 높았다. 이것은 폴리머라텍스의 수소함유량에 따라 카본휘스커의 직경과 밀도를 조절하는 것이 가능할 것으로 보인다.

• 한국환경보건학회지
• /
• 제36권1호
• /
• pp.61-71
• /
• 2010

Intensive measurements of airborne respirable $PM_{2.5}$ and inhalable $PM_{2.5}$ were conducted in the downtown area of Iksan city. The $PM_{2.5}$ and $PM_{2.5}$ samples were collected twice a day in the Iksan city of Korea from October 17 to November 1, 2004. The purpose of the study was to determine the inorganic water-soluble components and trace elements of $PM_{2.5}$ and $PM_{2.5}$ in the atmospheric environment and estimate the contribution rate of major chemical components from a mass balance of all measured particulate species. The chemical analysis for PM samples was conducted for water-soluble inorganic ions using ion chromatography and trace elements using PIXE analysis. The mean concentrations of respirable $PM_{2.5}$ and inhalable $PM_{2.5}$ were $51.4{\pm}29.7$ and $79.5{\pm}39.6\;{\mu}g/m^3$, respectively, and the ratio was 0.62. The ion species of $NO_3$, $SO_4^2$, and $NH_4^+$ were abundant in both $PM_{2.5}$ and $PM_{2.5}$. These components predominated in respirable $PM_{2.5}$ fraction, while $Na^+$, $Mg^{2+}$, $Ca^{2+}$ mostly existed in coarse particle mode. Elemental components of S, Cl, K, and Si were abundant in both $PM_{2.5}$ and $PM_{2.5}$. These elements, except for Si, were considered to be emitted from anthropogenic sources, while Si, Al, Fe, Ca existed mainly in coarse particle mode and were considered to be emitted from crustal materials. The averaged mass balance analysis showed that ammonium nitrate, ammonium sulfate, crustal component, and other trace elements were composed of 18.4%, 13.2%, 4.8%, 3.5% for PM2.5 and 17.0%, 11.6%, 13.7%, 4.4% for $PM_{2.5}$, respectively.

• 자원리싸이클링
• /
• 제17권2호
• /
• pp.30-35
• /
• 2008

혼합 호산성 박테리아를 이용하여 리튬이온 밧데리 산업 폐기물로부터 코발트와 리튬의 침출을 연구하였다. 혼합 호산성 박테리아의 성장기질은 단체 황 및 2가 철이온으로 구성되어 있으며 미생물에 의한 금속의 침출은 폐기물에 존재하는 금속과 황산이온의 양자 반응 때문에 일어난다. 본 연구에서 12일간 미생물 침출반응시 고상 폐기물중 코발트의 80%, 리튬의 20%가 용해되었으며 고액비가 높을수록 금속의 독성으로 인하여 미생물의 성장은 억제된다. 단체 황의 농도가 높을 조건에서는 일부 황 분말이 용해되지 않으며 금속의 침출속도는 황의 증가에 따라 감소한다.

• Asian Journal of Atmospheric Environment
• /
• 제11권2호
• /
• pp.79-95
• /
• 2017

A number of field studies have provided evidence that biomass burning is one of the major global sources of atmospheric particles. In this study, we have collected $PM_{2.5}$ emitted from biomass burning combusted at open burning and laboratory chamber situations. The open burning experiment was conducted with the cooperation of 9 farmers in Chiba Prefecture, Japan, while the chamber experiment was designed to evaluate the characteristics of chemical components among 14 different plant species. The analyzed categories were $PM_{2.5}$ mass concentration, organic carbon (OC), elemental carbon (EC), ionic components ($Na^+$, ${NH_4}^+$, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $Cl^-$, ${NO_3}^-$ and ${SO_4}^{2-}$), water-soluble organic carbon (WSOC), water-insoluble inorganic carbon (WIOC), char-EC and soot-EC. OC was the dominant chemical component, accounting for the major fraction of primary $PM_{2.5}$ derived from biomass burning, followed by EC. Ionic components contributed a small portion of $PM_{2.5}$, as well as that of $K^+$. In some cases, $K^+$ is used as biomass burning tracer; however, the observations obtained in this study suggest that $K^+$ may not always be suitable as a tracer for biomass burning emissions. Also, the results of all the samples tested indicate relatively low values of char-EC compared to soot-EC. From our results, careful consideration should be given to the usage of $K^+$ and char-EC as indicators of biomass burning. The calculated ratios of WSOC/OC and WIOC/OC were 55.7% and 44.3% on average for all samples, which showed no large difference between them. The organic materials to OC ratio, which is often used for chemical mass closure model, was roughly estimated by two independent methods, resulting in a factor of 1.7 for biomass burning emissions.