• Resources Recycling
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• v.23 no.5
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• pp.12-20
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• 2014

Calcium ferrite is a major bonding material self-fluxed sintered ore, and it is used as a flux in the steelmaking process. Calcium ferrite is more effective binder for making sintered ore and flux for steel making because of it's low melting temperature. In this Study, calcium ferrite was made by using variety industrial by-products from steel plant. The property of calcium ferrites was investigated on the basis of test method using in the cement manufacturing process. Crystal analysis, compression test as well as thermal analysis were carried out to evaluate physical properties of calcium ferrite.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.129-129
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• 2003

본 연구는 음식물 퇴비의 합리적인 시용량을 검증하고, 3년 연용에 의한 토양 변화 및 고추 생육과 수량에 미치는 영향을 평가하고 돈분퇴비를 시용한 대조구와 생육 및 품질 면에서 비교 분석하여 적정한 퇴비 시용량을 설정하기 위하여 실시하였다. 처리구는 1, 2, 3차 연도 모두 동일한 방법으로 무처리구, 대조구(2ton/10a의 돈분퇴비), 음식물 퇴비 2t, 4t, 6t, 8ton/10a을 사용한 처리구 등 6개를 두었으며 3반복, 난괴법을 이용하였다. 음식물 퇴비와 돈분 퇴비의 이화학적 특성을 분석한 결과, 음식물 퇴비의 경우 1차 연도는 유기물과 NaCl 모두 부산물 비료의 공정규격에 적합하였으나, 2차 연도는 유기물이, 3차 연도는 NaCl이 공정규격에 적합하지 않았다. 그리고 돈분 퇴비의 경우 수분함량이 약간의 차이를 보였으나 공정규격을 벗어나지는 않았다. 토양은 음식물 퇴비 시용량이 증가할수록 대부분의 화학적 특성이 증가하였고, 연용에 의해서도 유기물, 치환성양이온, NaCl 등의 양이 증가함을 보여 염류집적이 일어나고 있음을 확인할 수 있었다. 또, 음식물 퇴비 시용량증가에 따라 비중은 낮아지고 공극률이 증가하여 물리성 개선에 도움을 주었으나, 1, 2, 3차 연도를 비교해 보았을 때 큰 차이는 없었다. 고추의 생육과 수량에 있어서도 음식물 퇴비 시용량이 증가할수록 초기 생육이 저조하였으며, 그로 인해 수량이 감소하였다. 또한 3년 연용으로 인한 음식물 퇴비의 축적으로 수량의 감소와 품질 저하를 초래하였다. 음식물 퇴비의 연용에서 2ton/10a 이상의 시용은 수량의 감소를 초래하였다. 이러한 결과로 볼 때 음식물 퇴비를 2ton/10a 이하로 사용하면 큰 무리는 없겠지만 장기 연용은 삼가는 것이 좋을 것이라 판단된다. 따라서 음식물 퇴비를 다른 일반 퇴비 제조의 중간 원료나, 또는 혼합 사용하는 시험을 계속 진행 중에 있다.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.654-661
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• 2017

Recently, a low-impact development (LID) technic such as a wetland has been proposed as a Nature-friendly process for reducing pollutants caused by livestock wastewater. Therefore, the Daphnia magna toxicity was analyzed for livestock wastewater samples, to determine if a wetland system would also be effective in reducing this ecotoxicity. In the present study, acute D. magna toxicity was not significantly dependent on the presence and type of reed, nor type of media. However, when treated with construction wetlands, ecotoxicities decreased as well as TN, TP and COD concentrations. Therefore, it is considered that a construction wetland system with bio reeds and bio-media as well as general reeds would be effective to reduce the ecotoxicity of livestock wastewater. To apply a wetland system as the subsequent treatment process to a livestock waste water treatment facility, it is necessary to perform an integrated evaluation such as treatment efficiency and the ecotoxicity test for various characteristics of livestock wastewater.

• Journal of Korea Foundry Society
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• v.42 no.4
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• pp.218-225
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• 2022

For hydrogen-vehicle applications (air pressure control valve housing, APCVH), an investigation was conducted to determine how micro-defects in a high- pressure die-casted Al alloy (industrial code: ALDC12) could be controlled by means of a post-treatment using an organic-based impregnation solution in order to improve the air- tightness of the die-casted Al sample. Two different impregnation solutions were proposed and its test results were compared to a imported product from Japan with respect to the processing variables used. A structural investigation of the components under study was conducted by means of computer tomography and 3D X-ray micro-CT. These observations revealed that the use of the impregnation treatment to seal micro-defects led to highly significant and beneficial changes which were attributed mainly to interconnections among inherent micro-pores. A leak test after impregnation revealed that the performance improvement rate of the die-casted Al sample was ~70% for INNO-01. Therefore, the developed impregnation solutions offer an effective strategy to control the micro-defects found in various vehicle parts via die-casting.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.388-394
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• 2014

BACKGROUND: Aclonifen is used as a systemic and selective herbicide to control a wide spectrum broad-leaf weeds by inhibition carotenoid biosynthesis, and then its MRLs(Maximum Residue Limits) will be determined in onion and garlic. In this study, a new official method was developed for aclonifen determination in agricultural products to routinely inspect the violation of MRL as well as to evaluate the terminal residue level. METHODS AND RESULTS: Aclonifen was extracted from crop samples with acetone and the extract was partitioned with dichloromethane and then purified by silica solid phase extraction(SPE) cartridge. The purified samples were detected GC using an ECD detector. Limits of detection(LOD) was 0.001 mg/kg and quantification(LOQ) was 0.005 mg/kg, respectively. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$, n=5). The recoveries were ranged from 74.3 to 95.0% with relative standard deviations(RSDs) of less than 8%. All values were consistent with the criteria ranges requested in the Codex guidelines(CAC/GL 40). CONCLUSION: The proposed analytical method was accurate, effective and sensitive for aclonifen determination and it will be used to as an official method in Korea.

• Journal of Food Hygiene and Safety
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• v.30 no.3
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• pp.272-280
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• 2015

A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with $r^2$ > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.373-384
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• 2022

Fluoxastrobin a fungicide developed from Strobilurus species mushroom extracts, can be used as an effective pesticide to control fungal diseases. In this study, we optimized the extraction and purification of fluoxastrobin according to its physical and chemical properties using the QuEChERS method and developed an LC-MS/MS-based analysis method. For extraction, we used acetonitrile as the extraction solvent, along with MgSO₄ and PSA. The limit of quantitation of fluoxastrobin was 0.01 mg/kg. We used 0.01, 0.1, and 0.5 mg/kg of five representative agricultural products and treated them with fluoxastrobin. The coefficients of determination (R²) of fluoxastrobin and fluoxastrobin Z isomer were > 0.998. The average recovery rates of fluoxastrobin (n=5) and fluoxastrobin Z isomer were 75.5-100.3% and 75.0-103.9%, respectively. The relative standard deviations (RSDs) were < 5.5% and < 4.3% for fluoxastrobin and fluoxastrobin Z isomer, respectively. We also performed an interlaboratory validation at Gwangju Regional Food and Drug Administration and compared the recovery rates and RSDs obtained for fluoxastrobin and fluoxastrobin Z isomer at the external lab with our results to validate our analysis method. In the external lab, the average recovery rates and RSDs of fluoxastrobin and fluoxastrobin Z isomer at each concentration were 79.5-100.5% and 78.8-104.7% and < 18.1% and < 10.2%, respectively. In all treatment groups, the concentrations were less than those described by the 'Codex Alimentarius Commission' and the 'Standard procedure for preparing test methods for food, etc.'. Therefore, fluoxastrobin is safe for use as a pesticide.

• Korean Journal of Environmental Agriculture
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• v.22 no.3
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• pp.233-235
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• 2003

Heavy metal contents in commercial horticultural growing media were investigated Fifty-three samples were collected nationwide during 2000 to 2001 and heavy metals in the samples were analyzed by ICP-OES after acid digestion and 0.1N HCl extraction. Average contents of total Cd, Cr, Co, Ni, Pb, and Zn by acid digestion in the growing media were 0.69, 35.7, 14.9, 15.5, 12.7, and 54.8 mg/kg DW, respectively. The ranges of heavy metal in the growing media were $0{\sim}1.82$, $0{\sim}259.8$, $1.6{\sim}69.5$, $0{\sim}60.7$, $0{\sim}36.5$, $12.9{\sim}124.0\;mg/kg$ DW for Cd, Cr, Co, Ni, Pb, and Zn, respectively. Heavy metal contents in the commercial horticultural growing media were showed lower levels than the permitted levels for quality control described by Korean Standard Analytical Method for Growing Media. Average contents and ranges of 0.1 N HCl extractable heavy metals were 0.08 and $0{\sim}0.20$ for Cd, 0.38 and $0{\sim}2.10$ for Cr, 1.45 and $0{\sim}4.03$ for Cu, 0.85 and $0{\sim}3.31$ for Ni, 0.84 and $0{\sim}2.21$ for Pb, and 30.68 and $0.18{\sim}88.45\;mg/kg$ DW for Zn, respectively. These concentrations by 0.1 N HCl extraction showed much less levels than those of total heavy metals by acid digestion.

• Journal of Applied Biological Chemistry
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• v.55 no.1
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• pp.55-59
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• 2012

We designed a new rapid detection method for volatilized formaldehyde from wood. The process was installed with volatilizing and collecting parts in an incubator. For rapid sampling of formaldehyde from wood, we pulverized the wood to sawdust, and used 0.15-2.0 mm particles for the tests. The highest sampling rate (94.8%) was obtained at 40 mL/min flow rate and $100^{\circ}C$. Under the optimized condition, we could collect the volatilized formaldehyde with good recovery rate. The developed method was applied to the monitoring of the formaldehyde from wood, and the measured concentrations were 0.7-4.6 ${\mu}g/g$ from natural wood, 5.9-12.3 ${\mu}g/g$ from preserved wood, and 5.9-211.5 ${\mu}g/g$ from chemical adhesive processed wood. From the results, we identified natural wood sawdust and chemically processed wood (medium density fiberboard, high density fiberboard, particle board) by the formaldehyde contents except preserved wood.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.75-81
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• 2018

The effect of $Ar-N_2$ plasma treatment on Cu surface as one of solutions to realize reliable Cu-Cu wafer bonding was investigated. Structural characteristic of $Ar-N_2$ plasma treated Cu surface were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscope. Ar gas was used for a plasma ignition and to activate Cu surface by ion bombardment, and $N_2$ gas was used to protect the Cu surface from contamination such as -O or -OH by forming a passivation layer. The Cu specimen under high Ar partial pressure plasma treatment showed more copper oxide due to the activation on Cu surface, while Cu surface after high $N_2$ gas partial pressure plasma treatment showed less copper oxide due to the formation of Cu-N or Cu-O-N passivation layer. It was confirmed that nitrogen plasma can prohibit Cu-O formation on Cu surface, but nitrogen partial pressure in the $Ar-N_2$ plasma should be optimized for the formation of nitrogen passivation layer on the entire surface of Cu wafer.