• Korean Chemical Engineering Research
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• 제56권2호
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• pp.269-274
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• 2018

All the $Ni-Co-Ce-ZrO_2$ mixed oxides are prepared by co-precipitations methods. Methanation of CO and $H_2$ reaction is screened tested over different fractions of cerium (2, 4, 7 and 12 wt.%) over $Ni-Co/ZrO_2$ bimetallic catalysts are investigated. The mixed oxides are characterized by XRD, CO-Chemisorption, TGA and screened methanation of CO and $H_2$ at $360^{\circ}C$ for 3000 min on stream at typical ratio $CO:H_2=1:1$. In $Ni-Co/CeZrO_2$ series 2 wt.% Ce loading catalyst shows most promising catalyst for $CH_4$ selectivity than $CO_2$, which directs more stability with less coke formation. The high activity is attributed to the better bimetallic synergy and the well-developed crystalline phases of NiO, $ZrO_2$ and $Ce-ZrO_2$. Other bimetallic mixed oxides NCoZ, $NCoC^{4-12}Z$ has faster deactivation with low methanation activity. Finally, 2 wt.% Ce loading catalyst was found to be optimal coke resistant catalyst.

• 자원환경지질
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• 제40권6호
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• pp.727-738
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• 2007

운봉지역 하상퇴적물에 대한 지구화학적 특성규명을 통해, 주성분원소 및 미량원소에 대한 자연 배경치를 제시하고, 그 기반암(압쇄상화강암, Kim et al., 1992)과의 비교를 통해 지구화학적 재해에 대해 예견하고자 한다. 73개의 하상퇴적 물시료를 물이 흐르고 있는 1차 수계를 대상으로 채취하였고, XRD, XRF ICP-AES, NAA를 이용하여 주성분원소 및 미량성분원소를 분석하였다. 운봉지역의 주성분원소 함량은 $SiO_2\;36.94{\sim}65.39 wt.%,\;Al_2O_3\;10.15{\sim}21.77wt.%,\;Fe_2O_3\;3.17{\sim}10.90wt.%,\;CaO\;0.55{\sim}5.27wt.%,\;MgO\;0.52{\sim}4.94wt.%,\;K_2O\;1.38{\sim}4.54wt.%,\;Na_2O\;0.49{\sim}3.36wt.%,\;TiO_2\;0.39{\sim}1.27wt.%,\;MnO\;0.04{\sim}0.22wt.%,\;P_2O_5\;0.08{\sim}0.54wt.%$의 범위를 보이며, 미량성분 및 희토류원소 함량은, $Cu\;4.8{\sim}134ppm,\;Pb\;24.2{\sim}82.5ppm,\;Sr\;95.9{\sim}739ppm,\;V\;19.9{\sim}124ppm,\;Zr\;52.9{\sim}145ppm,\;Li\;25.2{\sim}3.3ppm,\;Co\;3.87{\sim}50.0ppm,\;Cr\;17.4{\sim}234ppm,\;Hf\;3.93{\sim}25.2ppm,\;Sc\;4.60{\sim}20.6ppm,\;Th\;3.82{\sim}36.9ppm,\;Ce\;45.7{\sim}243ppm,\;Eu\;0.89{\sim}2.69ppm,\;Yb\;1.42{\sim}5.18ppm$의 범위를 보인다. 주성분원소의 함량비교에서 CaO, $Na_2O,\;K_2O$ 함량은 하상퇴적물에서 기반암(압쇄상화강암류, Kim et al., 1992)인 압쇄상화강암류보다 높게 나타난다. 그리고 $Al_2O_3$와 $SiO_2$는 하상퇴적물과 기반암(압쇄상화강암류, Kim et al., 1992) 모두에서 높은 상관관계를 보인다. 하상퇴적물에서는 $SiO_2$ 함량이 높아질수록 희토류원소 함량도 같이 증가하는 특징을 보이나, 압쇄상화강암류에서는 $SiO_2$ 함량이 높아질수록 희토류원소 함량은 감소하는 특징을 보인다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.185-187
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• 2012

The characteristics of stratified co-flow flames have been investigated from the flame chemiluminescence images. The fuel lean premixed flame could be stabilized with a fuel rich premixed flames that is generated with the supply of fuel through the inner nozzle. The penetration of outer region lean premixture into the fuel stream produced a lifted rich premixed flame at the center. Chemiluminescence images of OH, CH, and $C_2$ radicals indicated that the way of stratification of fuel/air mixture under various operating conditions.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.263-266
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• 2012

The characteristics of mild combustion and pollutant emission were investigated computationally with supplied air stream temperature and dilution rate in jet flame. The air was diluted with main combustion products. As dilution rate increased at fixed air temperature, the temperature distribution of burner inside was uniformed and the maximum mole fraction of CO and NO was decreased. In addition, emission indices for NO, CO, and $CO_2$ were compared with air temperature and dilution rate.

• 한국환경과학회지
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• 제29권6호
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• pp.659-672
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• 2020

Water and sediment qualities were investigated in the Oncheon Stream and at the Wondong bridge of the Suyoung River, during the summer rainy season, 2019. Dissolved oxygen (DO) showed the lowest levels at 4.7 and 5.0 m/L, and biogeochemical oxygen demand (BOD) showed the highest at 5.3 mg/L downstream where the tributary flows into the main river. Chemical oxygen demand (COD) increased from 2.0 to 5.9 mg/L on average as it flowed downstream, The COD/BOD ratio decreased gradually as it flowed downstream, reaching 1.0. However, COD/BOD ratio at the Wondong bridge was 5.8-22.2, indicating that easily biodegradable and non-biodegradable organic matter flows into the Oncheon Stream and Suyoung River, respectively. Total nitrogen (T-N) / total phosphorus (T-P) ratio tended to decrease from 72 to 21 as it flowed downstream, measuring 71 to 86 at the Wondong bridge. The water quality index (WQI) generally improved better than grade IV after heavy rainfalls. However, DO and T-P were the parameters that deteriorated the WQI. Ignition loss (IL), COD, T-N, and T-P of sediments had distribution of 1.44 ± 1.01%, 0.35 ± 0.16%, 43 ± 63 mg/kg, and 10.9 ± 21.9 mg/kg, respectively. These were several times lower than the annual averages of IL, T-N, and T-P in 2017 before the dredging project was conducted in the first half of 2018.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.

• 자원환경지질
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• 제33권3호
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• pp.205-215
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• 2000

The Anyang River runs through highly industrialized area and joins the lower part of the Han River. loading out large amounts of potential pollutants. Attempts were made to understand geochemical behavior of trace elements in the stream sedimens collected from the bottom of the river and the stream water. Bottom sediments, suspended solids and stream waters were collected and analysed for the chemical and mineralogical composition. Heavy metals including Cr, Zn, Ni, and Co in the sediments were enriched appeared to reflect anthropogenic input. Pb, Cu, As were also enriched between several to 10 times , compared to background levels. Although some heavy metals were derived from anthropogeic input, geochemical associations seem to implyh much of the elements are originated from natural sources as well, mainly from granitic rocks . This is also supported by the mineralogical composition of the suspended solids, which are mainly composed of quartz, feldspar and mica. Most of the elements are associated with total carbon and clay sized fractions, with high values of correlation coefficient. Most of the elements are associated with total carbon and clay sized fractions , with high values of correlation coefficient. It was noteworthy that Hg was detected between 2 and 4 ppb in the stream water.

• 자원환경지질
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• 제35권6호
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• pp.509-521
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• 2002

본 연구는 지화학적 재해를 평가하는 좋은 지시자인 하상퇴적물에 대하여 지질집단별 지구화학적 특성과 하천수의 특성을 장흥지역 1차 수계를 중심으로 밝히고자 한다. 암석의 생성시기와 지질학적 환경에 따라 풍화에 영향을 받은 정도에 차이가 많은 점을 고려하여 연구지역의 지질을 화강암류지역, 화강암질편마암류(일부 변성퇴적암류포함)지역, 응회암류지역으로 나누어 주성분원소, 미량원소, 희토류원소, 독성원소 등의 분포특성에 대하여 기술하였다. 하천수에 대한 온도, pH. 전기전도도 등의 물리화학적 특성은 1999년과 2001년에 현장에서 측정하였고, 하상퇴적물 시료는 1999년 4월과 5월에 걸쳐 채취하였으며, XRF ICP-AES, NAA를 이용하여 화학분석을 실시하였다. 주성분원소의 함량은 지질집단에 관계없이 비슷한 함량비를 나타냈으며, 희토류원소는 화강암질편마암류(일부 변성퇴적암류 포함)지역에서 다른 두 지역에 비해 낮게 나타났고, 독성원소 중 Zn과 Cu가 비교적 높은 함량을 나타내었다. 부화계수와 부화지수를 도출한 결과 주성분 원소에서는 $Fe_2O_3$, MgO, $TiO_2$, MnO가, 희토류원소에서는 응회암류지역의 시료들 중 Eu. Yb가, 독성원소에서는 Co, Cr, Zn에서 약간의 부화경향을 나타냈다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.167-174
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• 2004

Several metalliferous and coal mines, including Myungjin, Seojin and Okdong located at the upper watershed of Okdong stream, were abandoned or closed since 1988 due to the mining industry promotion policy and thus disposed an enormous amount of mining wastes without a proper treatment facilities, resulting in water pollution in the downstream areas. AMD and waste effluents from the closed coal mines were very strongly acidic showing pH ranges of 2.7 to 4.5 and had a high level of total dissolved solid (TDS) showing the ranges of 1,030 to 1,947 mg/L. Also heavy metal concentrations in these samples such as Fe, Cu, Cd and anion such as sulfate were very high. These parameters of AMD and effluents were considered to be highly polluted as compared to those in the main stream area of the Okdong river and be major pollutants for water and soil in tile downstream area. Pollution indices of the surface water at the upper stream of Okdong river where AMD of the abandoned coal mines was flowed into main stream were in the ranges of 16.3 to 47.1. On the other hand, those at the mid stream where effluents from tailing dams and coal mines flowed into main stream were in tile ranges of 10.6 to 19.5. However, those at the lower stream were ranged from 10.6 to 14.9 These results indicated that mining wastes such as AMD and effluents from the closed mines were tile major source to water pollution at the Okdong stream areas.

• 자원환경지질
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• 제29권6호
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• pp.733-738
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• 1996

Heavy metal equilibria in the Dongnam stream which receives the wastewater from mining activities are investigated to provide some basic data for the management of small stream with acid mine drainage. Saturation, undersaturation, and supersaturation of some heavy metal ions with respect to some mineral phases are evaluated by saturation index (logIAP/Ksp). The $Al^{3+}$ activities showed equilibrium with $AIOHSO_4$ solid phase below a pH of 6.0. The $Fe^{3+}$ activities appeared to be controlled by Fe $(OH)_{3(amorphous)}$ solid phase below a pH of 4.0. $Zn^{2+}$ activities appeared to be regulated by $ZnCO_3$ solid phase above a pH of 6.8. Some heavy metal activities appeared to be depended upon the pH.