• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2003.10a
• /
• pp.246-251
• /
• 2003

전기분해법을 이용하여 수용액 중의 질산성 질소의 환원거동에 대한 연구를 통하여 수용액중의 질산 함량을 제어하는 연구를 수행하였다. 촉매전극을 채택한 복극전해조에서 30분의 조업에 질산 100ppm 이하의 저농도 용액은 70%, 300ppm 이상의 고농도의 경우는 90%까지 질소를 용이하게 제거할 수 있었다. 초기 질소농도가 증가하면서 한계전류밀도도 크게 증가하였으며, pH가 감소할수록 환원전류가 증가하였다. 그리고 수용액의 pH는 질소 환원반응기구에 큰 영향을 주는 것으로 판명되었으며, 산성에서는 질소형태로 중성 혹은 염기성에서는 암모니아 형태로 환원되는 것으로 추정된다.

• Water for future
• /
• v.25 no.2
• /
• pp.99-110
• /
• 1992

A problem of outlet salinity from a stratified fluid with a well developed interface thickness consisting of an upper and lower layer differing slightly in density is considered. Three kinds of apparatus were used for the experimental test and salinity differences between inlet layer and outlet discharge were estimated by the functional relationship using the dimensionless values. For the critical incipient condition of withdrawal of upper layer, Densimetric Froude number is correlated by the inlet diameter and depth ratio in the tank.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.262-267
• /
• 1997

금속형 사용후핵연료 관리모형으로 직경 3 cm, 길이 248.5cm인 금속봉을 19개 장전한 캐니스터가 x-y 방향으로 무한 격자배열된 경우에 대해 캐니스터의 두께, 간격 및 외부의 공기중 수분농도의 변화에 따른 핵임계도 분석을 수행하였다. 미임계한계치(k$_{eff}$=0.95) 근방에서 최대 핵임계도를 나타내는 각 인자값을 구하고, 미임계 상태를 유지하는 조건을 제시했다. 그 결과, 캐니스터의 두께가 7mm인 경우의 최대 핵임계도 값은 0.94401 $\pm$ 0.00050으로서, 공기중 수분농도가 0.34 g/㎤이고 간격이 4.8 cm인 경우에 나타났다. 8 mm인 경우의 최대 핵임계도 값은 0.91182 $\pm$0.00050이며, 캐니스터간의 간격이 4.4cm이고 공기중 수분농도가 0.35 g/㎤일 때 나타났다. 8 mm 캐니스터의 금속저장체 저장은 미임계 상태를 유지할 것으로 추정되었다.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.8 no.2
• /
• pp.185-192
• /
• 1996

In order to simulate the coastal dispersion effectively, hybrid concept of operator split Eulerian-lagrangian concentration model and random-walk particle tracking model are developed. Especially the random-walk model is adequate for region with steep slope of concentration. According to model tests, it agrees perfectly with analytical solution on around the source point for therefore. ▽C $\geq$ 0.005, meanwhile it shows poor results for ▽C$\leq$0.002. trial modeling for real situation therefore, random-walk model is applied for near field henceforth Eulerian-Lagrangian concentration model is adoped for whole domain so that overall performance and accuracy can be achieved by using developed hybrid model.

• Journal of Bio-Environment Control
• /
• v.16 no.4
• /
• pp.372-378
• /
• 2007

This study was carried out to investigate the effect of potassium concentrations in fertigation solution on growth and development of nutrient deficiency symptoms of leaf perilla (Perilla frutesens). The nutrient concentrations in above ground plant tissue, petiole sap and soil solution of root media were also determined. Potassium deficiency symptoms developed in older leaves with marginal necrosis. The brown areas on the lower leaves enlarged rapidly and the margins became scorched. Elevation of K concentrations in the fertigation solution up to 8 mM increased the crop growth in leaf length, stem thickness, and fresh and dry matter production of above ground plant tissue. However, that decreased the chlorophyll contents. The 8.0 mM K treatment which showed the greatest growth had 5.01 g in dry weight and 2.76% in K content of above ground plant tissue, suggesting that maintaining K content higher than 1.7% is necessary for good growth of Perilla frutesens. The K concentrations in petiole sap and soil solution of 8.0 mM treatment were $12,289mg{\cdot}kg^{-1}\;and\;11.65mg{\cdot}L^{-1}$, respectively. These indicated that K fertilization to maintain higher than $8,700mg{\cdot}kg^{-1}$ in petiole sap and $4.5mg{\cdot}L^{-1}$ in soil solution are necessary to ensure good crop growth.

• The Korean Journal of Pesticide Science
• /
• v.8 no.4
• /
• pp.280-287
• /
• 2004

We investigated the residual amounts of endosulfan and procymidone taken by vegetables grown in hydroponics culture and field conditions treated with the pesticides in order to evaluate safe cultivation concentration of the pesticides in the vegetables. Endosulfan and procymidone were selected as test pesticides because they have been reported to frequently detect in agricultural products at different concentrations. In hydroponic culture, by Chinese cabbage, procymidone was absorbed 3.8 times higher than endosulfan. The higher the pesticide concentration get, the worse the plant grew. In soil treated with 10 mg/kg of endosulfan, the pesticide absorbed by Leafy radish, Chinese cabbage and radish was less then their MRLs. In case of carlot, the residue level in soil which did not exceed its MRL was 1 mg/kg. The concentrations of procymidone in soil which did not exceed the MRLs in Leafy radish, Chinese cabbage, radish and carrot were 10, 10, 2 and 1 mg/kg, respectively Usually aged endosulfan and procymidone residues were less absorbed into crops than the fresh ones. Chinese cabbage absorbed more endosulfan and pocymidone than leafy radish, radish doing more than carrot.

• Korean Journal of Food Science and Technology
• /
• v.48 no.4
• /
• pp.329-334
• /
• 2016

The inhibitory effect of epigallocatechin gallate (EGCG), one of the antioxidants in green tea (Camellia sinensis), against Salmonella Enteritidis was evaluated in commercial braised quail eggs at two temperatures (4 and $25^{\circ}C$). Although S. Enteritidis was dose-dependently suppressed by EGCG in pure culture at $25^{\circ}C$, it was not inhibited in the sauce or eggs at this temperature. At low temperature ($4^{\circ}C$), S. Enteritidis was inhibited in both the sauce and eggs by $400{\mu}g/mL$ EGCG. Thus, EGCG at an appropriate concentration could be a useful food additive for inhibiting S. Enteritidis in braised quail eggs at low temperatures.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2011.04a
• /
• pp.376-377
• /
• 2011

최근 Mg, Mg-Al합금, Al은 전자제품의 케이스, 차량의 휠 등의 신소재로서 활용성이 높아 사회적 수요가 급격히 늘고 있다. 이러한 수요 증가와 함께 관련 사업장에서는 취급 과정에서 폭발사고 위험성이 높아지고 있는데, 2010년도에는 국내 사업장에서 금속 분진에 의한 폭발사고가 4건이 발생하여 인명 및 재산피해가 발생하였다. Mg-Al합금의 폭발사고로 사망 1명과 부상 2명이 발생하였으며, Al분진의 폭발사고는 3건이 발생하여 사망 2명과 부상 3명의 인명피해로 이어졌다. 사고조사를 통하여 사업장에서의 금속분진에 대한 위험인식이 매우 낮은 것이 유사 사고가 반복되고 있는 가장 큰 이유로 알려지고 있는데, 이는 금속분진에 대한 부족한 안전기술정보와 밀접한 관련이 있다. 본 연구에서는 Mg, Mg-Al합금, Al등을 취급하는 관련 사업장에서 폭발사고 예방대책을 위하여 활용할 수 있는 폭발특성에 관한 안전기술정보 제공을 목적으로 하고 있다. 보다 구체적으로는 사고 다발 금속분진에 대한 위험성 이해에 도움을 될 수 있도록 동일 입경분포 조건에서의 위험성을 정량적으로 평가하였으며, 이를 위하여 각 금속분진의 동일 입경 조건에서 최대폭발압력, 폭발하한계 등의 폭발위험성 데이터를 실험적으로 조사 하였다. 조사한 시료는 평균입경 200 mesh의 Al, Mg, Mg-Al(60:40 wt%)로서 입도분석기(Beckman Coulter LSI 3320)를 사용하여 측정한 결과 평균입경은 약 $155{\mu}m$로 나타났다. Al분진의 농도변화에 따른 폭발압력을 조사한 결과, 최대폭발압력(Pmax)은 7.9 bar였으며 최대폭발압력상승속도 (dt/dP)max는 농도 $1500[g/m^3]$에서 322 [bar/s]로 최대가 되었으며 폭발 하한계(LEL)는 $70[g/m^3]$가 얻어졌다. 반면에 순수한 Mg의 LEL은 $30[g/m^3]$였으며 Pmax는 6.4 bar, (dP/dt)max는 100 [bar/s]가 얻어졌다. 이러한 결과로부터 LEL이 낮은 Mg는 Al보다 연소성이 큰 것으로 나타났으며, Al은 화염을 유지하는데 필요한 최저 열분해 가스농도를 확보하는데 Mg보다도 고농도의 분진이 필요함을 알 수 있었다. 또한 Mg-Al(60:40 wt%)의 LEL은 $50g/m^3$이었으며 Pmax는 9.4 bar, (dP/dt)max는 472 [bar/s]가 얻어졌다. 이러한 결과로부터 Mg-Al(60:40 wt%)합금의 연소성을 살펴보면 착화하기 쉬운 정도는 Mg와 Al의 성분비에 의해 변화하지만 Mg와 Al의 중간 정도로 나타나는 반면, Pmax는 Mg 또는 Al의 단독 물질 성분보다도 매우 큰 것을 알 수 있었다. 본 연구를 통하여 단일 성분의 Mg와 Al보다도 Mg와 Al이 일정 비율로 구성된 Mg-Al합금의 경우가 화재폭발 위험성이 증가한다는 사실을 알 수 있었으며, 이와 같은 폭발위험특성 자료를 활용하여 분진의 보관, 취급, 폐기 등의 지속적 관리가 필요하며 사업장 특성에 적합한 안전대책을 통한 사고예방대책이 요구된다.

• Applied Chemistry for Engineering
• /
• v.23 no.5
• /
• pp.505-509
• /
• 2012

In this study, we investigate the use of new carbon nanotube paste electrode (CNPE) for promoting the detection of lead (Pb) heavy metal in the a drinkable water, which negatively affects human brain and nerve system. For the evaluations, CNPE is served as a working electrode, while sensitivity and limit of detection (LOD) of Pb are measured in DI and tap water based electrolytes using squarewave anodic stripping voltammetry (SWASV). As a result of that, in the 25~150 ppb range of $Pb^{2+}$ ions, its sensitivity and calculated LOD are $12.85\;{\mu}A/{\mu}M$ and 26 ppb in DI water based 0.1 M $H_{2}SO_{4}$ electrolyte while they are $10.36\;{\mu}A/{\mu}M$ and 38 ppb electrolytes respectively. In addition, experimentally measured LOD values of Pb are 4 ppb and 10 ppb in the two water electrolytes. The stripping of $Pb^{2+}$ ion is also controlled by surface reaction. Our experimental data are then compared with those of other already published references. With the comparison, it is proved that our electrode outperforms other electrodes in terms of the sensitivity and LOD of trace Pb metal.

• Journal of Korea Water Resources Association
• /
• v.32 no.6
• /
• pp.741-749
• /
• 1999

This study is to develop a method of measuring the soil water concentration by using TDR, which is based on the relationships between the bulk soil electrical conductivity of soil and the reflected wave of TDR. The proposed monitoring method is combined with two important relationships. One is that between the bulk soil electrical conductivity and the solute concentration, which is known to be linear at a constant volumetric soil water content and the other is that between the relative bulk soil electrical conductivity and the water content at a constant concentration. Some formulas have been proposed to solve the second relationship, but a new formula and the critical water content are proposed to improve the accuracy of measurement. This proposed formula estimates the relative bulk soil electrical conductivity for water contents which is divided to two regions, linear and nonlinear, by the critical water content. As the result of the comparison with other formulas, the proposed formula is proved to be superior to other formulas and to be an available method to apply to the unsaturated transient solute transport.