• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.375-383
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• 2020

BACKGROUND: Bisphenol A (BPA) is a chemical widely used in polycarbonate plastics, epoxy resins. BPA is an endocrine disruptor. Residue of BPA in agricultural environments is a major concern. The objective of this study was to understand the characteristics of the uptake and distribution of BPA and its metabolites introduced into the agricultural environment to crops, and to use it as basic data for further research on reduction of BPA in agricultural products. METHODS AND RESULTS: This study established the analysis method of BPA and its metabolites in soil and crops, and estimated the intake of BPA and its metabolites from lettuce (Lactuca sativa) grown in sandy loam and loam soil, which are representative soils in Korea. The two major metabolites of BPA were 4-hydroxyacetophenone (4-HAP) and 4-hydroxybenzoic acid (4-HBA). BPA, 4-HAP and 4-HBA have been analyzed by using liquid chromatography tandem mass spectrometry (LC-MS/MS). These substances were detected in sandy loam and loam soil, indicating that certain portions of BPA were converted to 4-HAP and 4-HBA in the soil; however, it was observed that only 4-HBA migrated to lettuce through the roots into crops. CONCLUSION: The uptake residues showed the BPA and 4-HAP were not detected in lettuces grown on sandy loam (SL) and loam (L) soil treatments that were applied with of 10 ng/g, 50 ng/kg and 500 ng/g of BPA. However, the 4-HBA was detected at the level of 7 ng/g and 11 ng/g in the lettuce grown in sandy loam and loam soil that were treated with the 500 ng/g of BPA, respectively, while the 8 ng/g of 4-HBA was measured in the lettuce cultivated in the loam that was treated with 100 ng/g of BPA. This result presents that the BPA persisting in the soil of the pot was absorbed through the lettuce roots and then distributed in the lettuce leaves at the converted form of 4-HBA, what is the oxidative metabolite of BPA.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.152.1-152.1
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• 2007

• 주택과사람들
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• s.195
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• pp.68-69
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• 2006

금융감독원이 발표한 '주택담보대출 리스크 관리 강화를 위한 추가조치'가 주택시장에 미치는 영향이 크다. 양도세, 재산세 등 각종 세금정책과 함께 대출한도 규제마저 실시되고 있어서 실수요자들이 내 집 마련을 하기 힘들게 됐다. '주택담보대출 리스크 관리 강화를 위한 추가조치'가 주택시장에 미치는 영향에 대해 살펴보았다.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.223.2-223
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• 2003

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.225.1-225
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• 2003

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.135.1-135
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• 2003

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.20-27
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• 2009

In this paper, HAPS operation scenario is proposed to minimize the interference from HAPS user terminal(HUT) to geostationary earth orbit(GEO) satellite receiver. The conventional scenario has been assumed for fully operated situation of HUT. However, all the HUTs could not be fully operated in a real system operation. Therefore, in order to reduce the interference to other systems, multibeam operation scenarios such as time division and adaptive time division methods are proposed and the interference effect of HUT to satellite receiver is evaluated according to various operation rate of HUT.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.527-537
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• 2012

The increasing consumption of pseudo-petroleum products (PPP) has been disturbing the national petroleum market. The use of PPP lead to tax evasion, disturbance of sound trading principles, component corrosion of cars, and explosion accident. Also, PPP have emitted hazardous air pollutants (HAP) including the carcinogenic aromatic hydrocarbons, PAHs and aldehydes more than regular-petroleum products. It thus has potentials to cause many environmental and health care problems. In this study, benzene, toluene and xylene emissions from road transport vehicles due to the use of pseudo-gasoline are estimated for the year 2008. The results of our study provide emission estimates of benzene, toluene and xylene for the year as 405, 1,711, 717 tonne/yr, respectively for regular-gasoline. BTX emissions are calculated as 452~515, 1,882~2,264 and 732~752 tonne/yr when the amount of pseudo-gasoline is estimated to account for 6~13% for regular-gasoline consumption. BTX emissions increased as much as 12~27, 10~32, 2~5% by using pseudo-gasoline. It is found that the pseudo-gasoline should be the key component to produce HAP in urban area.

• Journal of Digital Contents Society
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• v.9 no.1
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• pp.87-99
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• 2008

High Altitude Platform network systems utilize Unmanned Aerial Vehicle as routers for ground node communication. For this purpose, geographical clustering of ground nodes must be required. In this paper, we assume mobile ground nodes over wide area and the clusters composed of ground nodes are identified. UAVs can be positioned at the point of centroid of clusters. The number of UAVs are derived from the area size and the number of ground nodes deployed in that area. From the simulation and application of clustering algorithms, we showed visual clustering results with dynamic variance of number of ground nodes.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.126-130
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• 2006

Nano-sized hydroxyapatite (HAp) powders were synthesized by a microwave-hydrothermal method using $H_3PO_4\;and\;Ca(OH)_2$ as starting materials. The applied microwave powers and mole ratio of Ca/P were served as powerful factors in the synthesis of calcium phosphate. In the case of relatively low microwave power of 450 Wand Ca/P ratio of 1.57, the mixed calcium phosphate compounds were detected in the synthesized powders. But in the case of running at 550 Wand 1.67(Ca/P), the synthesized powder showed the monophase of HAp having two kinds of morphologies. One was a needle shape with $5\~15\;nm$ in width and $20\~50\;nm$ in length, and the other was a spherical shape of $10\~40\;nm$ in diameter.