• 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%.

• Transactions of Materials Processing
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• v.26 no.5
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• pp.306-313
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• 2017

This study investigated the microstructure, tensile strength, and high cycle fatigue properties of ADC12 aluminum alloys with different $Mg+Al_2Ca$ contents manufactured using die casting process. Microstructural observation identified the presence of ${\alpha}-Al$, eutectic Si, $Al_2Cu$, and Fe-intermetallic phases. The increase of $Mg+Al_2Ca$ content resulted in finer pore size and decreased pore distribution. Room temperature tensile strength tests were conducted at strain rate of $1{\times}10^{-3}/sec$. For 0.6%Mg ADC12, measured UTS, YS, and El were 305.2MPa, 157.0MPa, and 2.7%, respectively. For 0.8%Mg ADC12, measured UTS, YS, and El were 311.2 MPa, 159.4 MPa, and 2.4%, respectively. Therefore, 0.8% ADC12 alloy had higher strength and slightly decreased elongation compared to 0.6% Mg ADC12. High cycle fatigue tests revealed that 0.6% Mg ADC12 alloy had a fatigue limit of 150 MPa while 0.8% Mg ADC12 had a fatigue limit of 160MPa. It was confirmed that $Mg+Al_2Ca$ added ADC12 alloy achieved finer, spherical eutectic Si particles, and $Al_2Cu$ phases with greater mechanical and fatigue properties since size and distribution of pores and shrinkage cavities decreased as $Mg+Al_2Ca$ content increased.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.15-21
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• 2004

Objectives of this study were to monitor the distribution of heavy metals, to compare extractable heavy metal with total content and to investigate the relationships between soil physico-chemical properties and heavy metals in orchard soil. Sampling sites were 48 in Gyeonggi, 36 in Gangwon, 36 in Chungbuk, and 44 in Chungnam, Soils were collected farm form two depths, 0 to 20 and 20 to 40 cm (here after referred to as upper and lower layers) from March to May in 1998. Total contents of heavy metal in soils were analyzed by ICP-OES after acid digestion ($HNO_3$:HCl:$H_2O_2$) whereas extractable contents were measured after successive extraction of 0.1N-HCl, 0.05 M-EDTA, and 0.005 M-DTPA. Mercury was analysed by mercury atomizer. The average contents of Cd Cu, and Pb in the extractant with 0.1N-HCl at upper layer were 0.080, 4.23, and 3.42 mg/kg, respectively. As content in the extractant with 1N-HCl was 0.44 mg/kg, and total contents of Zn, Ni and Hg were 78.9, 16.1, and 0.052 mg/kg, respectively. The ratios of concentrations of heavy metals to threshold values (Cd 1.5, Cu 50, Pb 100, Zn 300, Ni 40, Hg 4 mg/ke in Soil Environmental Conservation Act in Korea (2001) were low in the range of $1/2.5{\sim}1/76.9$ in orchard soils. The ratios of extractable heavy metal to total content ranged $5.4{\sim}9.21%$ for Cd, $27.9{\sim}47.8%$ for Cu, $12.6{\sim}21.8$% for Pb, $15.8{\sim}20.3%$ for Zn, $5.3{\sim}6.3%$ for Ni, and $0.7{\sim}3.6%$ for Zn, respectively. Cu and Pb contents in 0.05 M-EDTA extractable solution were higher than those in the other extractable solution. Total contents of Cd, Ni and Ni in soils were negatively correlated with sand content but positively correlated with silt and clay contents. Ratios of extractable heavy metal to total content were negatively correlated with clay content but ai and Ni contents were positively correlated with soil pH, organic matter, and available phosphorous. Therefore, the orchard soil was safe because the heavy metal contents of orchard soil were very low as compared to its threshold value in the Soil Environmental Conservation Act. However, it need to consider the input of agricultural materials to the agricultural land for farming practices for assessment of heavy metals.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.339-342
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• 2007

$Cu(In_{1-x}Ga_{x})Se_2$(CIGS)는 매우 큰 광흡수계수를 가지고 있으므로 박막형 태양전지의 광흡수층 재료로서 많은 연구가 진행되고 있다. 박막이 태양전지의 광흡수층으로 이용되기 위해서는 큰 결정크기와 평탄한 표면, 적당한 전기적 특성을 가져야 한다. 이러한 특성들은 CIGS 박막의 조성에 큰 영향을 받고 있는 것으로 보고되고 있다. 본 연구에서는 동시증발법을 이용하여 Cu/(In+Ga) 비를 0.9로 고정한 후 Ga 조성(Ga/(In+Ga)의 비 : 0.32, 0.49, 0.69, 0.8, 1)을 변화시켜 Wide band gap CIGS 박막태양전지를 만들었다. 기판은 soda line glass를 사용하였고 뒷면 전극으로는 Mo를 스퍼터링법으로 증착하였다. 또한 버퍼층으로는 기존에 쓰이고 있는 CdS를 CBD(Chemical Bath Deposition)법으로 층착시켰으며, 윈도우층으로는 i-ZnO/n-ZnO를 스파터링 법으로 층착하였다. 그리고 앞면전극으로는 Al을 E-beam 으로 증착하였다. 분석은 XRD, SEM, QE로 분석하였다. 위 실험에서 얻은 결과로는 Ga/(In+Ga)비가 증가할수록 Cu(In,Ga)Se2 박막은 회절 peak들이 큰 회절각으로 이동하였고, 이것은 Ga 원자와 In 원자의 원자반경의 차이에서 기인된 것으로 사료된다. 또한 Ga 조성이 증가할수록 단파장 쪽으로 이동하는 것을 볼 수 있으며, Voc가 증가하다가 에너지 밴드캡이 1.62 eV 이상에서는 Voc가 감소하는 것을 볼 수 있는데 이것은 Ga 조성이 증가할수록 에너지 밴드캡이 커지면서 defect level 이 존재하기 때문인 것으로 사료된다. Ga/(In+Ga)비가 1일 때의 변환효율은 8.5 %이고， Voc : 0.74 (V), Jsc : 17.2 ($mA/cm^{2}$), F.F : 66.6(%) 이다.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.3-9
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• 1999

The grain morphology, the changes in morphology and Jc with the thermo-mechanical treatment (TMT) history, the field dependence of Jc and the nature of intergranular bonding were studied in $T_{10.8}$$Pb_{.2}$$Bi_{0.2}$$Sr_{1.8}$$Ba_{0.2}$$Ca_{2.2}$$Cu_{3}$$O_{z}$/Ag tapes. As a result, incorporation of intermediate rolling during the final heat-treatment resulted in of plate-like TI-1223 grains, and thus enhanced Jc. Jc's near 2.5$\times$104 A/cm2 at 77 K and 0 T were obtained in just rolled tapes with an excellent reproducibility. The high Jc's seem to grain-connectivity easy recovery of excellent grain-connectivity during final heat-treatment after inter -mediate rolling, probably due to retarded T1 evaporation and excessive Ca content in the present composition. The strong field dependence of Jc even in low fields, however, indicated that there still existed significant weak-links and the degree of directional grain-alignment was far from the desired one. The intergranular binding in the tapes seemed to be mainly dominated by SIS junctions.

• Resources Recycling
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• v.8 no.5
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• pp.44-50
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• 1999

The sbdy iwestlgaled ihc propa-ties of Lhe dust\ulcorner rrom fe~~oallomya ~~ufacturTeh. e chemical composition, cornpasitlon material, p d c l e sire md shapes of the bulk dust, sired dust and magnetically separated durl were mvesligaled. As the re\ulcornerulL, we suppose that the dust from &gh Carbon Fenama~~gunesMc anuiact~vingP rocess is not sufiicient as solulce material of Mn because of ale low Mn canlenl (13.5%) and complicaled composition mate~ial. The dust from Bug F!lter or AOD Proccss is mi~inlym ade up of 0.2-2 pm Mn30, (Hausmam~iu)p iutlde in spherical shape and thc Mn content is 63.190.The dust from Cooler of AOD Process is inninly made up of coarse Ca(O1-Or)zM. n,FeyO,, SiO, and fine Mn30d.

• Progress in Superconductivity and Cryogenics
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• v.8 no.1
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• pp.15-18
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• 2006

A new precursor solution wilt low fluorine content was synthesized for MOD processing of coated conductors. In this study, the precursor solution for MOD processing was synthesized using F-free yttrium and copper precursor. It was shown that crack-free and uniform precursor films were formed after calcination in humidified oxygen atmosphere. Less than 2 hours were required to finish the calcination process. The relatively gradual weight loss during the calcination process is attributed to the feasibility of fast calcination profile. The calcined precursor film was converted to a YBCO film without any secondary phases after annealing in wet $Ar/O_2$ atmosphere. Fully converted film shows uniform microstructure and high critical current density. $(Jc=2.7MA/cm^2) $.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.489-493
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• 2016

In this study, the effect of vanadium oxide ($V_2O_5$) content and pre-sintering atmosphere on sealing property of glass frit that consisted of $V_2O_5-BaO-ZnO-P_2O_5-TeO_2-CuO-Fe_2O_3-SeO_2$ was investigated by XPS (X-ray photoelectron spectroscopy). The content of V2O5 was changed to 15, 30, and 45 mol%, and the pre-sintering was carried out in air and $N_2$ condition, respectively. XPS analysis conducted before and after laser irradiation with identical sample. Before laser treatment, glass frits that were pre-sintered at air condition showed both $V^{4+}$ and $V^{5+}$, but the valence state was changed to $V^{5+}$ after laser irradiation when the glass frits contained 30 and 45 mol% $V_2O_5$; this change led to non-adhesive property. On the other hand, glass frits that were pre-sintered at $N_2$ condition exhibited only $V^{4+}$ and it showed fine adhesion irrespective of the $V_2O_5$ content. As a result, the existence of $V^{4+}$ seems to be a major factor for controlling the adhesive property of glass frit for laser sealing.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.142-150
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• 1994

To investigate differences in Cd and Zn contents of paddy soils and rice plants polluted by the municipal and industrial waste water in the Mangyeong River Area, soil and plant samples were collected at several distances from the main inlet and at different depths of the soil. Soil samples were extracted with $4M-HNO_3$ and plant samples were digested with a mixture of $HNO_3$and $HClO_4$for analyzing heavy metals by atomic absorption spectrophotometry. The contents of Cd and Zn in soils ranged from 0.38 to 1.17 and from 33.8 to 464.6mg kg^{-1}, respectively. The average Cd level in 1990 was less than that in 1982, but the Zn level in 1990 was higher than that in 1982 in general. No variation in Cd contents was observed in soils at the different distances from the source of waste water, but Zn contents in soils were lower with the increasing distances from the source of waste water. A significant correlation was observed among Cd content, OM, available silicate, CEC and $Ca^{++}$. Similar results existed among Zn content of 1982, OM and $Ca^{++}$. The Cd content in subsurface soils of 1992 was significantly correlated with Zn, Cu, and Pb in soils, and the Zn content in soils was significantly correlated with the Cu and Pb in soils, regardless of years. The Cd content in leaf blades of rice was more than seven times higher than that in brown rice. The Zn content in rice was higher than that in leaf blades and in panicle axis. The Cd content in panicle axis and the Zn content in all parts of rice were correlated with Zn, Cu and Pb contents in soils. The Cd and Zn contents in brown rice ranged from 0.10 to 0.90mg $kg^{-1}$ and from 4.2 to 95.9mg $kg^{-1}$ in the Mangyeong River Area, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.646-649
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• 2002

The microwave dielectric properties and the structure of $Sb_2O_5$ modified $BiNb_xSb_{1-x}O_4$ ceramics were investigated. The structure of these ceramics were orthohombic phase at all sintering temperatures and there were not the second phase. These ceramics added sintering additive such as CuO and $V_2O_5$ were sinterable at a low temperature$(880^{\circ}C{\sim}960^{\circ}C)$ by liquid phase. Dielectric properties of $BiNb_xSb_{1-x}O_4$ ceramics were also improved than these of $BiNbO_4$ ceramics. The content of modified atom controlled the microstructure, dielectric constant and quality factor. As a result, We could obtain following result; ${\varepsilon}r$=42~44, $Q{\cdot}f_0$=20,000~42,000GHz, $\tau_f=-7{\sim}-28ppm/^{\circ}C$.