• 한국주조공학회지
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• 제31권6호
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• pp.362-365
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• 2011

In the present work, the corrosion properties of Mg-xSn (x = 1, 3, 5, 7 and 9 wt.%) alloys have been investigated. Potentiodynamic polarization and immersion tests were carried out in 3.5% NaCl solution of pH 7.2 at room temperature to measure the corrosion properties of Mg-xSn (x = 1, 3, 5, 7 and 9 wt.%) alloys. With increase of the Sn contents, the volume fraction of the $Mg_2Sn$ phase was increased. The corrosion rate of Mg-xSn alloys was increased up to 7 wt.%Sn and decreased above 9 wt.%Sn. Initiation of galvanic site during immersion mainly occurred at Mg/$Mg_2Sn$ interface and propagation went into ${\alpha}$-Mg. For this reason, corrosion properties of Mg-xSn (added from 1 wt.%Sn to 7 wt.%Sn alloys) alloys are decreased because the galvanic site was increased with increasing Sn addition. In Mg-9wt.%Sn alloy, however, the corrosion site were changed from Mg/$Mg_2Sn$ interface to ${\alpha}$-Mg/$M_2Sng$ interface in lamellar structure. Preferentially corrosion of ${\alpha}$-Mg/$M_2Sn$ interface in lamellar structure impeded corrosion propagation went into ${\alpha}$-Mg.

• Journal of Plant Biotechnology
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• 제30권2호
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• pp.207-214
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• 2003

This study was carried out to establish a novel bioassay system for screening of compounds affecting aromatic amino acid or anthocyanin biosynthesis through investigating a degree of sucrose-induced anthocyanin formation such as size of plant material, buffer conditions, light intensity and irradiated duration, incubation temp., etc were determined and standard procedure (suitable experimental condition) was set up as follows. The second leaf blade of white corn seeding induced by fluridone treatment were segmented into a size of 5${\times}$5 min. The segments were floated on the solution of 1% sucrose in 1.0mM MES buffer (pH6.0∼6.5) and incubated at 26$^{\circ}C$ for 2days under the continuous light condition(70∼100$\mu$mol m$^{-2}$ s$^{-1}$ ). Anthocyanin in the purpled tissues was extracted with methanol containing 1% HCl and the optical density of the clear supematants was determined at 528mm. Influences of some chemicals were tested using this system. Glyphosate, 5-enolpyruvylshikimate 3-phosphate synthase inhibitor, showed most sensitive response with I$_{50}$ value at 3.3$\mu$M. Dicyclohexylcarbodiimide(DCCD) and parachloromercuribenzenesulfonic acid(PCMBS) had a relatively strong ingibition with I50 value at 7.1$\mu$M and 10.2$\mu$M, respectively. These results show that sucrose-induced anthocyanin formation in white com leaf segment provide a very simple and rapid system for searching new compounds affecting aromatic amino acid or anteocyanin biosynthesis by screening at less than 10$\mu$M.

• 생명과학회지
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• 제5권2호
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• pp.14-14
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• 1995

The effect of lipoxygenase (LOX) on the oxidation and co-oxidation of lipid fraction was studied in the model system of rainbow trout. For the reaction in model system 1 g of lipid fraction and 50mL of enzyme extract(LOX, 140 unit in 50mL phosphate buffer solution at pH 7,4)), which were obtained from rainbow trout, were homoginized in the presence of Tween 20 and kept at 23$\circ$C for 3 days. The activity of LOX was decreased to 43% of initial level during the reaction in the model system. The initial composition of rainbow trout lipid was showed to be consisted of trigliceride(TG;82%) and free fatty acid(FFA;0.1%), while this converted to 59% of TG and 20% of FIFA, respectively after reaction in model system. Change of fatty acid composition was also observed and the content of linoleic acid, one of the major fatte acids, was decreased to 13% from 54% in the content of total fatty acids after reaction. The carotenoids in rainbow trout were composed of 0.4% $\alpha$-carotene, 1.6% $\beta$ -carotene, 80% canthaxanthin, 7% lutein and 11% zeaxanthin, thus the canthaxanthin was the major component. This canthaxanthin was the most degraded carotenoid by lipoxygenase catalyzed co-oxidation during the reaction. On the other hand the tocopherol isomers found in the rainbow trout were $\alpha$ and $\beta$ -tocopherol, and $\alpha$-tocopherol had a higher degradation rate by the lipoxygenase catalyzed co-oxidation than of $\beta$-tocopherol in the reaction of model system.

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.4169-4172
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• 2012

Background: The majority of women in rural India have poor or no access to cervical cancer screening services, although one.quarter of all cervical cancers in the world occur there. Several large trials have proven the efficacy of low-tech cervical cancer screening methods in the Indian context but none have documented the necessary components and processes of implementing this evidence in a low-resource setting. Methods: This paper discusses a feasible model of implementation of cervical cancer screening programme in low-resource settings developed through a pilot research project carried out in rural Tamilnadu, India. The programme used visual inspection of cervix after acetic acid application (VIA) as a screening tool, nurses in the primary care centres as the primary screeners and peer educators within Self-Help Women groups to raise community awareness. Results: The uptake of screening was initially low despite the access to a screening programme. However, the programme witnessed an incremental increase in the number of women accessing screening with increasing community awareness. Conclusions: The investigators recommend 4 key components to programme implementation in low-resource setting: 1) Evidence-based, cost-effective test and treatment available within the reach of the community; 2) Appropriate referral pathways; 3) Skilled health workers and necessary equipment; and 4) Optimisation of health literacy, beliefs, attitudes of the community.

• 대한화학회지
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• 제7권1호
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• pp.17-24
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• 1963

本硏究에서는 韓國産 灰重石($CaWO_4$)에 關하여 固相一液相界面에 있어서의 電氣化學的 性質을 電氣泳動法으로 調査하고 한便 浮遊性에 關하여서는 捕收劑로 Dodecyl ammonium chloride(D.A.C.라 略稱)와 Sodium dodecyl sulfate(S.D.S.라 略稱)를 使用하여 Hallimond tube 試驗, 接觸角測定 及 吸着量測定等의 捕收劑 이온이 鑛物表面에 吸着하는데 있어서 電氣的인 相互作用이 重要한 役割을 하고 있다는 것을 實證하였다. 卽 電氣泳動法으로 鑛粒의 水溶液中에 있어서의 mobility를 測定한 結果 灰重石의 境遇에는 $Ca^{++}$ 或은 $WO_4^{--}$이 界面 電氣特性을 決定하는 potental determining ion이라는 것이 確認되었고 水溶液中에 있는 $Ca^{++}$의 增加는 鑛粒界面의 陰電荷를 減少하며 $WO_4^{--}$의 增加는 그 陰電荷를 增加한다는 것을 알수 있다. 이와같은 表面에 "陰이온系"의 S.D.S. 或은 "陽이온系"의 D.A.C.를 作用시키면 當然히 S.D.S.는 $Ca^{++}$의 增加에 따라 吸着量이 增加되어 浮遊性이 增大되고 한便 D.A.C. 때는 反對로 $WO_4^{--}$이 增加하는데 따라 吸着量이 增加되며 따라서 浮遊性도 增大된다고 불수 있고 實地로 捕收劑吸着量의 測定 및 Hallimond tube 實驗은 이것을 立證하고 있다. 이러한 基礎的인 究明은 灰重石浮選理論의 根幹이 되는 것이고 從來의 浮選法 改良에 對한 指針이 될수 있다고 生覺한다.

• Bulletin of the Korean Chemical Society
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• 제32권2호
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• pp.444-450
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• 2011

A novel method that utilizes poly(5-methyl-2-thiozyl methacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid-co-divinylbenzene) [MTMAAm/AMPS/DVB] as a solid-phase extractant was developed for simultaneous preconcentration of trace Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), and Zn(II) prior to the measurement by flame atomic absorpiton spectrometry (FAAS). Experimental conditions for effective adsorption of the metal ions were optimized using column procedures. The optimum pH value for the simultaneously separation of the metal ions on the new adsorbent was 2.5. Effects of concentration and volume of elution solution, sample flow rate, sample volume and interfering ions on the recovery of the analytes were investigated. A high preconcentration factor, 100, and low relative standard deviation values, $\leq$1.5% (n = 10), were obtained. The detection limits (${\mu}gL^{-1}$) based on the 3s criterion were 0.18 for Cd(II), 0.11 for Co(II), 0.07 for Cr(III), 0.12 for Cu(II), 0.18 for Fe(III), 0.67 for Mn(II), 0.13 for Ni(II), 0.06 for Pb(II), and 0.09 for Zn(II). The validation of the procedure was performed by the analysis of two certified reference materials. The presented method was applied to the determination of the analytes in various environmental samples with satisfactory results.

• 한국자원식물학회지
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• 제24권3호
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• pp.314-318
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• 2011

Saururus chinensis is used as a raw material of an anti-rheumatic, poultice, sedative and stomachic. The tea of dried Saururus chinensis leaves has a function of relaxing pains in back and breast and of treating stomach ailments. The plant has the functions of anti-inflammatory, depurative, diuretic, febrifuge and refrigerant. The extraction of functional material is carried out by methanol and ethanol solvents. Mechanochemical grinding is applied as a pretreatment process before extraction to enhance the extraction efficiency by increasing the surface area of the materials while changing the chemical properties of the materials. Extraction of functional materials from the Saururus chinensis after grinding as a pretreatment using the mechanochemical technology was accomplished in this study to investigate the effect of grinding on the antioxidant activities of the extract. Saururus chinensis was ground by the planetary ball mill and the morphology was analyzed by SEM. Mechanochemical pretreatment increased the yields of functional materials from 5.9 g to 6.4, 7.0, and 8.1 g after grinding of 30 minutes, 1 hour and 2 hours, respectively. Nitrite scavenging ability increased from 53.0-71.0% to 61.0-79.0% for the methanol extraction in the solution of pH 1.2. Also, Electron donating abilities were increased from 7.90-33.51% to 11.97-38.51% for the methanol extraction. The extract concentration for the half inhibition of DPPH radicals was reduced from $278{\mu}g/mL$ in the original sample to $263{\mu}g/mL$ in the sample after grinding for the methanol extraction.

• 한국환경농학회:학술대회논문집
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• 한국환경농학회 2009년도 정기총회 및 국제심포지엄
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• pp.93-115
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• 2009

There are growing public concerns over crop and food safeties due to the elevated levels of heavy metals grown in contaminated soil. Heavy metals are classified as the chemical harmful risks for crop and food safety. With implementation of GAP, crop safety is controlled by many regulatory options for soil, irrigation water and fertilizers. Any attempt to retard the metal uptake by crops may be the best protocol to secure crop and food safety. This article reviews the management strategies for heavy metals in view of crop safety in Korea and demonstrates results from the field experiments to retard metal translocation from soil to crops by using chemical amendments and soil layer management methods. Major source of soil pollution by heavy metals has been related with mining activities. Risk assessment revealed that rice consumption and groundwater ingestion in the abandoned mining areas were the major exposure pathways for metals to human and the heavy metal showed the toxic effects on human health. Chemical amendments such as lime and slag retarded Cd uptake by rice (Oryza sativa L.) by increasing soil pH, lowering the phytoavailable Cd concentration in soil solution, immobilizing Cd in soil and converting the available Cd fractions into non-available fractions. The soil layer management methods decreased the Cd uptake by 76% and Pb by 60%. Either reversing the surface layer with subsurface layer or immobilization of metals with layer mixing with lime was considered to be the practical option for the in-situ remediation of the contaminated paddy soils. Combination of chemical soil amendments and layer management methods was efficient to retard the metal bioavailability and thus to secure crop safety for heavy metals. This protocol seems to be cheap, relatively easy to practice and practical in the agricultural fields. However, a long term monitoring work should be followed to verify the efficiency of this protocol.

• 한국가금학회지
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• 제14권2호
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• pp.89-96
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• 1987

본 연구에서는 가금에 있어 세포유전학적 방법을 이용하여 닭 염색체의 분리방법과 G, C-banding에 의한 분염분석 방법을 재고하여 보다 명확한 염색체의 형태적 양상을 제시하였다. 염색체의 분리는 성장중인 초기배아를 이용하므로써 유사분열 중기상을 쉽게 포악할 수 있었으며, 성장 4-5일째의 배아조직으로부터 염색체의 분리는 다소 불편함이 많았다. 가금에 있어 염색체 분리기술중 가장 중요한 것으로 적합한 sample의 채취와 적절한 중기상의 유도, hypotonic 처리에 따른 뚜렷한 형태의 유도, 도말방법 및 염색의 처리과정이다. 또한 보다 명확한 염색체의 분석을 위하여서는 중기 분열상중 초기 중기 상태의 상을 포착함이 바람직하다. G. C-banding 처리를 위해서는 공히 충분하고도 완전히 건조된 air-dried prepration된 sample을 이용하여야 바람직한 결과를 얻을 수 있으며, slide의 보존시간에 따라 band 양상에 많은 차이를 나타낸다. G-banding 양상에 크게 영향하는 요인으로서는 trypsin의 농도, 처리시간, 처리온도가 주된 작용을 하고, Giemsa solution에 사용하는 buffer의 pH도 크게 작용하는 것으로 나타났다. C-banding에 있어서는 Ba(OJ)$_2$의 농도 처리시간, 처리온도가 큰 영향을 미친 바 다소 짧은 시간의 처리가 바람직한 양상을 보이고, 처리전 HCl 처리로서 세포들의 균일성을 가하고, 처리후 철저한 수세가 좋은 결과를 나타내었다. Band 양상의 보다 정확한 해석을 위해서는 densitometer를 이용하므로써 구체적 양상을 분석할 수 있었다.

• 한국물환경학회지
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• 제21권1호
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• pp.84-91
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• 2005

$TiO_2-catalyst$ suspensions work efficiently in Photocatalytic oxidation (PCO) for wastewater treatment. Nevertheless, once photocatalysis is completed, separation of the catalyst from solution becomes the main problem. The PCO of Cu(II)-EDTA was studied to determine the reusability of the titanium dioxide catalyst. Aqueous solutions of $10^{-4}M$ Cu(II)-EDTA were treated using illuminated $TiO_2$ particles at pH 6 in a circulating reactor. $TiO_2$ was reused in PCO system for treatment of Cu(II)-EDTA comparing two procedures: reuse of water and $TiO_2$ and reuse of the entire suspension after PCO of Cu(II)-EDTA. The results are as follows; (i) Photocatalytic efficiency worsens with successive runs when catalyst and water are reused without separation and filtration, whereas, when $TiO_2$ is separated from water, the reused $TiO_2$ is not deactivated. (ii) The $TiO_2$ mean recovery (%) with reused $TiO_2$ was 86.4%(1.73g/L). Although the mean initial degradation rate of Cu(II)-EDTA and Cu(II) was lower than that using fresh $TiO_2$, there was no significant change in the rate during the course of the three-trial experiment. It is suggested that Cu(II)-EDTA could be effectively treated using an recycling procedure of PCO and catalyst recovery. (iii) However, without $TiO_2$ separation, the loss of efficiency of the PCO in the use of water and $TiO_2$ due to Cu(II), DOC remained from previous degradation and Cu(II)-EDTA added to the same suspension was observed after 2 trials, and resulted in the inhibition of the Cu(II)-EDTA, Cu(II) and DOC destruction.