• 한국지역사회생활과학회지
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• 제22권4호
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• pp.615-621
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• 2011

This study was conducted to evaluate of the protection efficiency in each part of developed pesticide-proof clothes by repeated washings. We investigated the effect of repeated laundering on mechanical properties of pesticide-proof clothes (not washed vs 5 times washed). We also examined pesticide infiltration rate into the pesticide-proof clothes by repeated laundering. The patches(TCL paper, surface area 50cm2)were attached to the inside of pesticide-proof clothes(head, chest, right upper-arm, right forearm, left thigh, left calf, back) which subjects had dressed in during pesticide spraying. The patches were detached from working clothes after work. For the extraction of pesticide in pesticide-proof clothes, sonication was applied for 30 min with methanol. The gas chromatography/mass spectrometry (GC/MS) was applied to identify the pesticide component. The results of this study are as follows: The force strength, water-vapour resistance and surface wetting resistance of pesticide-proof clothes decreased 5 times more in washed clothes. The concentration of pesticide was the highest in the head area of pesticide-proof clothes. In seven parts of TLC paper attached to the pesticide proof clothes, the concentration of pesticide was higher in the left thigh. The penetration part and concentration of pesticide increased as washing was repeated. Therefore the conclusion which can be drawn from this study is this: protection efficiency of pesticide-proof clothes decrease by repeated washings.

• 공업화학
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• 제35권2호
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• pp.115-121
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• 2024

본 연구는 W1/O/W2 이중유화법을 통한 마이크로 캡슐화 공정을 최적화하기 위해 역미셀(reverse micelle), salt 농도 등의 열역학적 변수와 유체의 점도, 계면장력 등 계면의 유동에 영향을 미치는 공정변수들의 영향성을 분석하였다. 아스코르브산의 PLA (polylactic acid) 미립자 내부로의 캡슐화 효율에 가장 큰 영향을 미치는 변수는 W1과 W2상의 삼투압의 차이로 W2상의 salt 농도를 높이거나, W1상의 아스코르브산 농도를 줄이면 캡슐화 효율이 높아짐을 관찰하였다. 또한, 삼투압의 차이가 클수록 미립자 표면의 손상이 심해짐을 확인할 수 있었다. 캡슐화 효율을 높일 것으로 예상되었던 역미셀 도입은 그 기여도가 낮거나 오히려 캡슐화 효율을 낮추었다. 마이크로캡슐의 수율은 공정 조건, 용액 조성 등과 상관없는 universal 함수로 표현하였는데, Ca > 20에서는 더 이상의 수율 증가가 관찰되지 않았다.

• 수도
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• 통권63호
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• pp.57-92
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• 1993

• 한국지진공학회논문집
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• 제10권4호
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• pp.67-76
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• 2006

본 논문에서는 철골 각형강관단면(RHS) 기둥-보 접합부에서 웨브의 모멘트 전달효율을 평가하였다. 먼저, 5개의 철골보접합부에 대한 비선형 유한요소해석을 수행하였다. 이들은 접합부 상세가 다르게 설계되었고, 따라서 휨저항 성능이 각기 다르다. 해석결과 RHS 기둥을 가진 모델은 기둥 플랜지의 면외변형 때문에 WF(Wide Flange) 기둥을 가진 모델에 비해 모멘트 전달효율이 저하함을 보였다. 스캘럽(WAH)과 얇은 강관기둥 두께도 모멘트 전달효율의 저하를 가져오는 원인으로서, 결과적으로 보-기둥 접합부의 파단을 초래할 가능성이 크다. 해석과 이전의 실험결과를 기초로 하면, 응력집중은 모멘트 전달효율과 반비례하고, 접합부의 변형능력은 모멘트 전달효율의 저하에 따라 감소하는 것을 알 수 있다. 더 나아가서 바닥슬래브가 있는 합성보 접합부에 대한 유한요소해석결과는 중립축이 상부플랜지 방향으로 상승함으로써 모멘트 전달효율이 저하했고, 이러한 영향은 접합부의 조기 취성파단을 초래하는 것을 보였다.

• 대한기계학회논문집B
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• 제28권3호
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• pp.281-288
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• 2004

Combustion using oxygen enriched air is an energy saving technology that can increase thermal efficiency by improving the burning rate and by increasing the flame temperature. Flame figures, OH radical intensities, temperature distributions and emissions concentration were examined according to oxygen enriched concentration(OEC) in a turbulent diffusion flat flame. As long as the oxygen enriched concentration was increased, the length and volume of the flat flame was decreased while OH radical intensity was raised and the flame temperature was increased. However, RMS of the fluctuating temperature was decreased, and more homogeneous temperature field was formed. Thermal NO also was increased with increase of oxygen enriched concentration, but CO was decreased due to the increase of chemical reaction rate.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.538-541
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• 2008

This study considers the feasibility of the concentration control of the feul and air by oscillating flow in the channel of Fuel Cells. Fuel Cell Stack performance is largely influenced by the fuel and air concentration. If the fuel and air concentration is lower than stoichiometry 1.25 of the fuel and 2.5 of the air, its performance deteriorates seriously because of the fuel and air starvation. In this respect the optimization of the fuel and air concentration is crucially important to maximize fuel cell stack performance. In this work, the effects of oscillating actuation are studied to control the concentration. Two important nondimensional parameters are introduced, each of which represents either the oscillating frequency or the oscillating amplitude. It is shown how these factors affect the stack performance and the efficiency of the fuel cell stack stack.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.27-30
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• 2007

This study considers the feasibility of the concentration control of the methanol solution by oscillating flow in the anode channel of passive type Direct Methanol Fuel Cells(DMFC). DMFC stack performance is largely influenced by the fuel concentration. If the fuel concentration is either lower than 0.5M or more than 2M, its performance deteriorates seriously because of the fuel starvation or the fuel crossover. In this respect the optimization of the fuel concentration is crucially important to maximize the DMFC stack performance. In this work, the effects of oscillating actuation in the fuel supply are studied to control the fuel concentration. Two important nondimensional parameters are introduced, each of which represents either the oscillating frequency or the oscillating amplitude. It is shown how these factors affect the stack performance and the efficiency of the DMFC stack.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.209-212
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• 2000

As a bench-scale study, transformation of nitrate to nitrogen gas under anoxic condition was determined by using autotrophic denitrifiers containing Thiobacillus denitrificans and elemental sulfur as an electron donor. The research objective is to measure the basic kinetic parameters of autotrophic denitrification reaction on the removal efficiency of nitrate. The results showed that nitrate was almost completely transformed to nitrite in the first 4 days of column operation. After 2 days of accumulation of nitrite, its concentration slowly decreased and the compound was detected less than 0.5 mg/L in 14 days. In the experiment, sulfate concentration in the effluent was the 70~90 mg-S/L and the pH was maintained around pH 7.5. When nitrate concentration of bank filtrate in the real field is considered, this sulfate concentration seems to be acceptable. At 17 cm from the bottom of the column, the effluent showed the highest nitrite concentration, and nitrate concentration decreased rapidly to the Point of 33 cm from the bottom. The results suggest that an appropriate thickness of permeable reactive barriers is about 30 cm.

• 상하수도학회지
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• 제23권6호
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• pp.735-741
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• 2009

This study intends to evaluate the efficiency of non-point source reduction technique by using the porous lightweight and recycled aggregate which microorganism is seeded. In case of infiltration velocity 30~70 mm/hr in high concentration of influent, it is indicated that SS was 40~94%, COD 44~91%, BOD 4~91%, TN 1.2~66%, TP 7~70% of removal efficiency. Removal efficiency is good in infiltration velocity 30 > 50 > 70㎜/hr order. Therefore, the non-point source treatment facility filled with lightweight and recycled aggregate using microbial seeding shows higher removal efficiency than a conventional sand and gravel. We confirm that the function and efficiency are improved significantly and applied to treat non-point sources.

• 한국환경보건학회지
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• 제27권3호
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• pp.11-20
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• 2001

An anaerobic sludge-aerobic fixed-bed biofilm(packed with ceramic support carrier of 1 inch size) reactor system was built up to treat textile wastewater. The efficiency of reactor system was examined by determining the effects of textile wastewater ratio(from 25% to 100% at HRT 24 h). The influent range of SCOD concentration and color were 1,036~1,357 mg/L, and 1,487~1,853 degree, respectively. When textile wastewater ratio was 100% and hydraulic retention time was 24 hours, SCOD removal efficiency by the anaerobic stage were 39.2% 100% and hydraulic retention time was 24 hours, SCOD removal efficiency by the anaerobic stage were 39.2% and the removal efficiency of the whole system were 75.8%. Color removal efficiency by the anaerobic stage were 45.4%(soluble color), and the removal efficiency of the whole system were 70.2%. In the A/A reactor system, the aerobic stage played an important role in removing both color and COD as well as anaerobic stage.