• Clean Technology
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• v.27 no.1
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• pp.69-78
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• 2021

Vegetable oils, such as palm oil and cashew nut shell liquid (CNSL), are used as major raw materials for bio-diesel in transportation and bio-heavy oil in power generation in South Korea. However, due to the high unsaturation degree caused by hydrocarbon double bonds and a high content of oxygen originating from the presence of carboxylic acid, the range of applications as fuel oil is limited. In this study, hydrotreating to saturate unsaturated hydrocarbons and remove oxygen in mixed bio-oil containing 1/1 v/v% palm oil and CNSL on monometallic catalysts (Ni and Cu) and bimetallic catalysts (Ni-Zn, Ni-Fe, Ni-Cu Ni-Co, Ni-Pd, and Ni-Pt) was perform under mild conditions (T = 250 ~ 400 ℃, P = 5 ~ 80 bar and LHSV = 1 h-1). The addition of noble metals and transition metals to Ni showed synergistic effects to improve both hydrogenation (HYD) and hydrodeoxygenation (HDO) activities. The most promising catalyst was Ni-Cu/��-Al2O3, and in the wide range of the Ni/Cu atomic ratio of 9/1~1/4, the conversion for HYD and HDO reactions of the catalysts were 90-93% and 95-99%, respectively. The tendency to exhibit almost constant reaction activity in these catalysts of different Ni/Cu atomic ratios implies a typical structure-insensitive reaction. The refined bio-oil produced by hydrotreating (HDY and HDO) had significantly lower iodine value, acid value, and kinetic viscosity than the raw bio-oil and the higher heating value (HHV) was increased by about 10%.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.443-443
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• 2014

CIS 박막을 제조하기 위한 방법으로 셀렌화(selenization)방식, MOCVD방식, 동시진공증발(co-evaporation)방식, 전착(electrodeposition)방식 등이 있으나, 이러한 방식을 이용하여 CuInSe2 박막을 제조하는 경우 어떤 방법으로든 다원화합물의 조성 및 결정성을 조절하기가 매우 어려운 단점이 있었다. 기판의 온도를 일정 온도로 유지하도록 하고, 증발원을 가열하여 이에 내포된 물질(이원화합물 또는 단일원소)을 증발시켜 기판에 증착이 이루어지도록 하거나, 기판의 온도를 승온시키고 구리 이원화합물을 내포한 증발원을 가열해 물질을 증발시켜 기판에 증착이 이루어지도록 하는 방법으로 기판에 박막이 형성되도록 한다. 기판의 대면적화로 인해 균일한 박막의 형성이 어려워지고 있으며, 이중 15% 이상의 고효율을 보인 방법은 3-stage process를 이용한 동시진공증발방식으로, Cu, In, Ga, Se 등의 각 원소를 동시에 진공 증발시키면서 조성을 조절하여 태양전지에 적절한 전기적, 광학적 특성을 가지는 Cu(In,Ga)Se2 (CIGS)박막을 증착시키는 방법이다. 일반적으로, 실험실에서 연구되고 있는 장비의 구조는 증발원이 아래에 장착되어서 상향 증착되는 방식이다. 본 연구에서 사용된 장비는 하향 증발원이 측면에 장착되어서 하향 증착되는 방식으로 구성하였다. 증착되는 면방향으로, 적외선온도계(pyrometer)가 설치된 시창(viewport)의 오염 등으로 인하여, 지속적인 공정이 이루어지기 힘든 점을 개선하여 증착기판의 후면에 적외선 온도계를 설치하여 기판의 온도변화를 감지하여 공정에 반영할 수 있도록 하였다. 본 연구에서는 하향식 진공 증발원, 기판후면 온도모니터링모듈 등을 개발 장착하여, CIGS 박막을 제조하였으며, 버퍼층은 moving 스퍼터링법으로 ZnS를 증착하였고, 투명전극층은 PLD(Pulsed Laser Deposition)를 이용하여 제조하였다. 가장 높은 광변환효율을 보인 Al/ZnO/CdS/Mo/SLG박막시료는 유효면적 $0.45cm^2$에 광변환효율 15.65 %, Jsc : $33.59mA/cm^2$, Voc : 0.64 V, FF : 73.09 %를 얻을 수 있었으며, CdS를 ZnS로 대체한 Al/ZnO/ZnS/Mo/SLG박막시료는 유효면적 $0.45cm^2$에 광변환효율 12.45 %, Jsc : $33.62mA/cm^2$, Voc : 0.59 V, FF : 62.35 %를 얻을 수 있었다.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.612-619
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• 2002

The dynamic behavior of Al-Mg alloys plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser irradiation. The keyhole fluctuated both in size and shape and its fluctuation period was about 440 ${\mu}{\textrm}{m}$. This instability has been estimated to be caused by the evaporation phenomena of metals with different boiling point and latent heats of vaporization. Therefore, the authors have conducted the spectroscopic diagnostics of plasma induced in the pulsed YAG laser welding of Al-Mg alloys in air and argon atmospheres. In the air environment, the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn, and singly ionized Mg line, as well as strong molecular spectrum of AlO, MgO and AIH. It was confirmed that the resonant lines of Al and Mg were strongly self-absorbed, in particular in the vicinity of pool surface. The self-absorption of atomic Mg line was more eminent in alloys containing higher Mg. These facts showed that the laser-induced plasma was relatively a low temperature and high density metallic vapor. The intensities of molecular spectra of AlO and MgO were different each other depending on the power density of laser beam. Under the low power density irradiation condition, the MgO band spectra were predominant in intensity, while the AlO spectra became much stronger in higher power density. In argon atmosphere the band spectra of MgO and AlO completely vanished, but AlH molecular spectra was detected clearly. The hydrogen source was presumably the hydrogen solved in the base Metal, absorbed water on the surface oxide layer or H$_2$ and $H_2O$ in the shielding gas. The temporal change in spectral line intensities was quite similar to the fluctuation of keyhole. The time average plasma temperature at 1 mm high above the surface of A5083 alloy was determined by the Boltzmann plot method of atomic Cr lines of different excitation energy. The obtained electron temperature was 3, 280$\pm$150 K which was about 500 K higher than the boiling point of pure aluminum. The electron number density was determined by measuring the relative intensities of the spectra1lines of atomic and singly ionized Magnesium, and the obtained value was 1.85 x 1019 1/㎥.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1385-1390
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• 2010

Repeated additions of untreated slurry to soil affected ecology and caused high levels of heavy metal in soil and ground water. The objective of this study was to evaluate heavy metal from hanwoo slurry with ferrous sulfate ($FeSO_4{\cdot}7H_2O$), aluminum sulfate [$Al_2(SO_4)_3{\cdot}14H_2O$, alum] and aluminum chloride ($AlCl_3{\cdot}6H_2O$) as a way to improve environmental management in hanwoo industry. The treatment rates, which were incorporated totally within the hanwoo slurry, were 1.0 g and 1.5 g of ferrous sulfate, alum and aluminum chloride/25 g of hanwoo slurry. The various rates of chemical additives significantly increased dry matter (9.98~13.94%) and decreased pH (3.48~6.52) compared with the controls. The use of chemical additives decreased Fe (11~29%), Al (7~12%), Zn (13~36%), and Cu (4~32%) contents, except for Fe in hanwoo slurry with ferrous sulfate and Al in hanwoo slurry with alum and aluminum chloride. In addition, the reduction in heavy metal should be associated with reduction in pH. In conclusion, the results of this study suggest that alum and aluminum chloride additives at rate of 1.5 g were cost-effective management practice that significantly reduces heavy metal from hanwoo slurry, while it may be improved environmental management.

• Ocean and Polar Research
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• v.26 no.2
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• pp.231-243
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• 2004

Sequential extraction was carried out on twenty two subsamples of three ferromanganese crusts from three seamounts (Lemkein, Lomilik, and Litakpooki) near the Marshall Islands in the western Pacific. The extraction was designed to fractionate Fe-Mn crust forming elements into low defined groups: (1) exchangeable and carbornate, (2) Mn-oxide, (3) Fe-oxyhyd.oxide, and (4) residual fraction. X-ray diffraction result shows that target material were well removed by each extraction step except for CFA in phosphatized crusts generation. According to chemical analysis of each leachate, most of elements in the Fe-Mn crusts are bound with two major phases. Mn, Ba, Co, Ni, Zn, (Fe, Sr, Cu, and V) are strongly bounded with Mn-oxide $({\delta}-MnO_2)$ phase, whereas Fe, Ti, Zr, Mo, Pb, Al, Cu,(V, P, and Zn) show chemical affinity with Fe-oxyhydroxide phase. This result indicates that significant amount of Al, Ti, and Zr can not be explained by detrital origin. Ca, Mg, K, and Sr mainly occur as exchangeable elements and/or carbonate phase. Outermost layer 1 and inner layer 2 which are both young crusts generations are similar in chemical speciations of elements. However, some of Fe-oxyhydroxide bounded elements (Pb, Y, Mo, Ba, Al, and V) in phosphatized innermost layer 3 are released during phosphatization and incorporated into phosphate (Pb, Y, Mo, and Ba) or Mn-oxide phase (Al and V). Our sequential extraction results reveal that chemical speciations of elements in the hydrogenetic crusts are more or less different from interelemental relationship calculated by statistical method based on bulk chemistry.

• Environmental Analysis Health and Toxicology
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• v.14 no.4
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• pp.155-163
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• 1999

Heavy metal accumulation in living organisms through food-wed can give serious damage on physiological responses for vital activities. The initiation of heavy metal supposed to begin from the bio-accumulation of plants. To establish basic data fur heavy metal contents in plants at the area without artificial contamination, both woody and herb plants at Mt. Kwang-Duk were studied. The content of heavy metals in various organs of plants were analyzed by ICP. The range of heavy metals in plants for Al, As, Cd, Co, Cr, Cu, Fe. Mn, Pb, Se and Zn were 1.019∼257.200ppm, O∼2.929ppm, 0∼0.079ppm, 0∼0.054ppm, 0.023∼3.007ppm, 0∼1.997ppm, 2.031∼148.500ppm, 1.069∼51.320ppm, O∼126.900ppm, 0.708∼4.927ppm and 0.846∼4.949ppm, respectively. The amount of heavy metals in plants are much less than that of soil except some species. In woody plants, it was detected that the metal contents of leaves were higher than that of stems especially in case of Al and Fe with statistical significance. There were significant differences between shoots and roots of herb plants in metal content of Al, Co and Fe. Those metals have more accumulated in roots comparing with shoots. Some species of plants had shown the difference tendency of heavy metal accumulation. Generally, most species had not exceeded over twice of mean value each other, and had various difference according to the kinds of heavy metals.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.374-374
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• 2011

Cu(In,Ga)Se2 (CIGS) 박막 태양전지는 일반적으로 Soda lime glass/Mo/CIGS/CdS/ZnO/ITO/Al의 구조로 제작된다. 태양전지는 p형과 n형 반도체의 접합에 의해서 동작을 하게 되며, CIGS 박막 태양전지에서는 p형으로 CIGS 박막과 n형으로 CdS 박막이 사용된다. CIGS 박막태양전지에서는 p형과 n형이 서로 다른 물질로 이루어진 이종접합을 이루게 되고, 계면에서의 밴드가 어떻게 형성이 되느냐에 따라 태양전지 성능에 영향을 미치게 된다. p형의 CIGS 박막은 주로 다단계 증발법에 의해 형성되고 3단계 공정조건에 의해 계면의 특성에 많은 영향을 미치게 된다. n형의 CdS 박막은 주로 chemical bath deposition (CBD) 법에 의해 제작된다. 이렇게 제작되는 CBD-CdS는 시약의 농도, pH (수소이온농도), 박막 형성시의 온도 등의 조건에 따라 특성이 변하게 된다. 본 논문에서는 3단계 공정시간을 변화시켜 제작된 CIGS 박막 위에 CBD-CdS 증착 조건 중 thiourea 의 농도를 변화시켜 CIGS 태양전지를 제작하고 그에 따른 특성을 살펴보았다. CIGS 박막은 3단계 공정시간을 490초와 360초로 하여 제작하였고, CdS 박막은 thiourea 농도를 각각 0.025 M과 0.05 M, 0.074 M, 0.1 M로 변화시켜가며 제작하였다. 제작된 CIGS 박막 태양전지는 CIGS 3단계 공정시간과 thiourea의 조건에 따라 최고 15.81%, 최저 14.13%로 나타내었다. 또한, 외부양자효율을 측정하여 제작된 CIGS 박막 태양전지의 파장에 따른 특성을 비교하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.792-795
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• 2007

본 연구 목적은 석탄 가스화를 통해 얻어진 합성가스를 이용하여 국내에서 개발된 DME 합성 촉매를 사용하여 DME 전환 공정에 대한 특성을 파악하는 것이다. 특히, DME 합성 반응에 가장 큰 영향을 미치는 합성 반응로의 온도 제어를 위하여 thermosyphon 시스템을 개발하여 DME 합성 반응에 최적온도로 알려진 $230{\sim}260^{\cdot}C$ 범위에서 제어가 가능함을 확인 하였다. 석탄 40 kg/h를 공급하였을 때 합성가스 유량은 $80{\sim}100$ $Nm^3/h$ 정도를 얻었다. DME 합성 반응에 사용한 촉매는 합성가스로부터 메탄올을 얻기 위한 촉매와 메탄올의 탈수 촉매(Cu/Zn/Al+r-$Al_2O_3$)를 혼합한 촉매를 사용하였다. DME 합성 반응로의 GHSV(1/kg$^{\cdot}C$cat h)는 $2500{\sim}3000$ 정도이며, 운전 압력 60기압에서 $H_2$ 전환율 $65{\sim}75%$, DME 선택도는 $69{\sim}79%$ 정도를 얻었다.

• Korean Journal of Materials Research
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• v.7 no.7
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• pp.564-570
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• 1997

용융산화에 의한 AI$_{2}$O$_{3}$복합재료의 형성에 미치는 합금원소의 영향을 연구하였다. AI-Mg-3Si 합금이 가장 우수한 산화거동을 보였다. 우수한 3원계로 선정된 AI-1Mg-3Si합금에 제 4원소 Sn, Cu, Ni, Zn을 양을 달리하여 각각 첨가하여 산화거동을 살펴보았다. 1273K, 1373K, 1473K, 에서 20시간 각각 산화실험을 한 결과, 1473K에서는 모든 합금계가 우수했으나 1373K, 1273K에서는 산화가 거의 일어나지 않았다.

• Journal of environmental and Sanitary engineering
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• v.9 no.2
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• pp.8-23
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• 1994

During the period from Mar., 1991 to Feb., 1992 66 tSP samples were collected by Hi volume air sampler at 1 sampling site in Seoul and the amount of concentration of 21 components(SO$_{4}$$^{2-}$, NO$_{3}$$^{-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Al, Ba, Ca, Cd, Cr, Cu, Fe, It Mg, Mn, Na, Ni, Pt Si, Ti, Zn, Zr ) were measured. And monthly and seasonal variation were surveyed and the principal component analysis( PCA ) were carried out with respect to these amount of pollutants, minimum of visibility and radiation on a horizontal surface. The total amount of soluble ion in water was high in order o(SO$_{4}$$^{2-}$> NO$_{3}$$^{-}$> N%'>Cl$^{-}$ and metal ion was high in order of Na> Ca>Si> Fe> Al> K> Mg> Zn> Pb> Cu>Ti> Mn > Ba> Cr> Zr> Ni> Cd. There was Seasonal variation in concentration for SO$_{4}$$^{2-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Na, Al, Ca, Bt Mg, Fe and Si. It was assumed that the components of the highest concentration on April were depend on yellow sand and the frequency of wind velocity and direction. As the results of PCA, the amount of pollution components was able to characterized with two principal components(Z$_{1}$, Z$_{2}$ ). The first principal components Z$_{1}$ was considered to be a factor indicating the pollutants originated from natural generation and The second principal components Z$_{2}$ was considered to be a factor indicating the pollutants originated from human work. The monthly concentration of pollutants in ISP, minimum of visibility and radiation on a horizontal surface was possible to evaluate by the use of these two principal components Z$_{1}$ and Z$_{2}$ .