• Journal of Advanced Marine Engineering and Technology
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• 제31권2호
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• pp.173-181
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• 2007

Recently, galvanizing method is predominantly being used not only a economical point of view but also due to it s stability and long life. For example, guard rail of high way, all kinds of structures for ship etc. were protected with galvanizing and demand of galvanized structural materials was being increased with more and more. However, galvanized structures were inevitably being deteriorated with time eventually because they were corroded with solution of galvanizing film and exfoliation of it s film in the present severe corrosive environment. Therefore, it is necessary to improve the corrosion resistance of the galvanizing film through various methods such as variation of chemical composition of galvanizing bath, chromate treatment and coating treatment. In this study, three test specimens such as pure galvanizing, galvarium, and chromate treatment were submerged at tap water with inhibitor addition. And the effect of their corrosion resistance improvement was comparatively investigated with electrochemical method. Corrosion current density of the galvanized steel was the largest among three specimens, however, the galvarium steel showed the lowest corrosion current density. Futhermore, these three kinds of test specimens indicated considerably excellent corrosion resistance by dipped at tap water with inhibitor addition. Especially, the galvanized steel showed the best effect of corrosion resistance improvement than other test specimens.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.429-429
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• 2008

Li$[Ni_{1/2}Co_{1/2}]O_2$ powder were synthesized from co-precipitation spherical metal oxide, $[Ni_{1/2}Co_{1/2}](OH)_2$. The preparation of metal hydroxide was significantly dependent on synthetic conditions, such as pH, amount of chelating agent, stirring speed, etc. The optimized condition resulted in $[Ni_{1/2}Co_{1/2}](OH)_2$, of which the particle size distribution was uniform and the particle shape was spherical, as observed by scanning electron microscopy. Calcination of the uniform metal hydroxide with LiOH at higher temperature led to a well-ordered layer-structured Li$[Ni_{1/2}Co_{1/2}]O_2$, as confirmed by X-ray diffraction pattern. Also these materials have ${\alpha}-NaFeO_2$ ($R\bar{3}m$) structure. Due to the homogeneity of the metal hydroxide, $[Ni_{1/2}Co_{1/2}](OH)_2$, the final product, Li$[Ni_{1/2}Co_{1/2}]O_2$, was also significantly uniform, i.e., the average particle size was of about 10 to 15 ${\mu}m$ in diameter and the distribution was relatively narrow. As a result, the corresponding tap-density was also high approximately 2.41 $gcm^{-3}$, of which the value is comparable to that of commercialized $LiCoO_2$.

• 수산해양기술연구
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• 제38권4호
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• pp.265-270
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• 2002

증류수 및 수도수 중에서 방열기로 사용되는 알루미늄합금재의 온도 변화, 탈기에 의한 개로전위, 부식전류밀도에 관하여 연구한 결과 다음과 같은 결론을 얻었다. 1. 청수 중에서 개로전위는 온도가 높아짐에 따라 비전위화 되고, 또한 탈기 후의 개로전위는 탈기 전의 개로전위보다 비전위화 된다. 2. 증류수 중에서의 부식전류밀도는 수도수 중에서의 부식전류밀도보다 더 억제된다. 3. 탈기 후의 부식전류밀도는 탈기 전의 부식전류밀도보다 크게 억제된다

• 한국양식학회지
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• 제21권1호
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• pp.47-53
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• 2008

본 연구의 목적은 rotifer Brachionus rotundiformis의 영양강화와 자어의 소화기능을 높이기 위해 소화효소 활성이 높은 rotifer의 선택방법을 제시하는 것이다. 소화효소 활성을 측정하는 개체군은 성장과정에 있는 개체군들 중 임의로 표본 수집하여 소화효소활성을 측정하여 결정하였다. 선택된 개체군에서 개체밀도와 성장률의 관계가 RD=5865 SGR-350.08(P<0.001)로 나타났다. 포란률은 성장률과 개체밀도와의 관계가 각각 F=-36.147 SGR+61.652(P<0.05)와 F=-0.0085 RD+66.38(P<0.001)로 나타났다. 성장률과 소화효소 활성의 rotifer 개체당 활성은 Amyl=-1.6482 SGR+3.2498(P<0.05), TAP=-0.8115 SGR+1.1361(P<0.001) 및 TGL+0.0055 SGR+0.0079(P=0.239)로 나타나 TG-lipase 활성에서는 성장률과 관계없는 것으로 나타났다. 또한 포란률과 rotifer 개체당 소화효소 활성의 관계는 Amyl=0.0296 F+1.0981(P<0.001). TAP=0.0252 F+0.0975(P<0.001) 및 TGL=-6E-06 F+0.0113(P=0.915)으로 나타나 TG-lipase 활성이 포란률과 관계없는 것으로 나타났다. 반면 TG-lipase의 단백질 비활성과 포란률, 성장률 및 개체밀도와의 관계는 각각 TGL=-0.0024 F0.2332(P=0.132), TGL=0.1267 SGR+0.005(P<0.01) 및 TGL=0.0002 F-0.0594(P<0.001)로 나타나 TG-lipase 단백질 비활성은 포란률과의 관계를 제외하고 각각 상관된 변화를 보였다. 따라서 rotifer의 영양강화효과와 자어에게 외부기인 소화효소 전달을 위한 높은 소화효소 활성을 보이는 rotifer 개체군이 개체밀도가 높은 개체군보다는 포란률이 높은 경우에 나타났기 때문에 포란률이 높은 개체군을 선택하여 영양강화하고 자어에 공급하는 것이 보다 자어에 유익할 것으로 판단된다.

• 한국세라믹학회지
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• 제32권4호
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• pp.462-470
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• 1995

The characteristics of spray-dried granules are important for dry pressing operation since they have great influences on die-filling, compaction ratio, and resulting green microstructure. An attempt was made to control granule morphology and the packing structure of fine Si3N4 particles in granules by adjusting suspension property. Mercury porosimetry was used to characterize the pore structures of both granules and green compacts. Finally, the effects of particle packing structure in granules and green microstructure on sintering behavior were investigated.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.135-139
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• 2002

Most of all the mechanical devices are becoming more high-speed and high-power as well as their used condition being more polluted. So, it is necessary for these devices to equip cooling system to overcome that kind of severe using condition. In this study, corrosion test was carried out in distilled and tap water for the investigation on the corrosion characteristics of Al-alloy that is using as material for radiator.

• 한국토양비료학회지
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• 제22권3호
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• pp.221-227
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• 1989

토성(土性)이 다른 두 토양(土壤)의 압밀상태(壓密狀態)가 대두(大豆)의 근생장특성(根生長特性)과 양분(養分)의 흡수기능처리(吸收機能差異)를 알아보기 위하여 용적밀도(容積密度)와 수분상태(水分狀態)를 달리한 Core에서의 유근신장(幼根伸長)과 용적밀도(容積密度)를 달리하여 pot재배(栽培)하였을 때 근(根)의 총(總)길이와 표면적(表面積), 근반경(根半徑) 및 양분(養分)의 흡수속도(吸收速度)를 조사(調査)한 결과(結果) 다음과 같다. 1. 대두(大豆)의 유근신장(幼根伸長)은 용적밀도(容積密度)가 낮을수록 빨랐으며 양토(壤土)에서는 토양수분(土壤水分) 상태(狀態)가 - 4bar 이하(以下)에서, 사양토(砂壤土)에서는 - 1bar 이하(以下)에서 급격(急激)히 감소(減少)하였다. 2. 유근(幼根)의 신장(伸長)은 ELE경도계(硬度計) 토양강도(土壤强度) 2.0 이상(以上)에서 급격(急激)히 감소(減少)하였으며, 근신장속도(根伸長速度)와 토양강도간(土壤强度間)에는 2차식(次式)으로 표시(表示)되었다. 그러나 사양토(砂壤土)에서 -10bar이하(以下)의 토양수분상태(土壤水分狀態)에서는 경도(硬度)에 관계(關係)없이 근신장속도(根伸長速度)가 낮았다. 3. pot재배시험(栽培試驗) 결과(結果), 뿌리의 총(總)길이는 용적밀도(容積密度)가 $1.2g/cm^3$인 양토(壤土)에서 가장 길었으며, $1.4g/cm^3$인 사양토(砂壤土)에서 가장 짧았다. 세근(細根)의 평균직경(平均直徑)은 사양토(砂壤土)에서 생육(生育)한 것이 양토(壤土)에서 생육(生育)한 것보다 굵었다. 뿌리의 총표면적(總表面積)은 용적밀도(容積密度)가 낮을수록 넓었으며, 양토(壤土)에서 사양토(砂壤土)보다 넓었다. 4. 양분(養分)의 흡수량(吸收量)은 건물생산(乾物生産)이 많은 양토(壤土)에서 많았다. 단위(單位)뿌리표면적당(表面積當) 흡수속도(吸收速度)는 질소(窒素)가 양토(壤土)에서 $597{\sim}753n\;mole/day{\cdot}cm^2$, 사양토(砂壤土)에서 $222{\sim}365n\;mole/day{\cdot}cm^2$이었으며, 용적밀도(容積密度)가 높은 토양(土壤)에서 높은 값을 보였다. K는 $99{\sim}175n\;mole/day{\cdot}cm^2$ P는 $26{\sim}46n\;mole/day{\cdot}cm^2$이었고, Ca와 Mg는 각각(各各) $175{\sim}230n\;mole/day{\cdot}cm^2$, $163{\sim}205n\;mole/day{\cdot}cm^2$의 범위(範圍)를 보였으며 토양간(土壤間)의 차이(差異)는 질소(窒素)보다 적은 경향(傾向)이었다.

• 산업기술연구
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• 제21권B호
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• pp.11-20
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• 2001

This laboratory study examined the impact of free chlorine residual and pipe material on the formation of biofilm in drinking water distribution pipe surfaces. Result of heterotrophic plate counts(HPC) of the biofilm in the tap water-supplied reactor averaged $2.17{\times}10^5CFU/cm^2$ on PVC and $2.43{\times}10^5CFU/cm^2$ on STS 316, respectively. HPCs on the surface exposed to the tap water containing 0.2mg/L of free chlorinne residual averaged $4.24{\times}10^4CFU/cm^2$ on PVC and $6.54{\times}10^4CFU/cm^2$ on STS 316, respectively. Average of HPC/Total direct counts in the tap water-supplied reactor ranged from 1.08%(PVC) to 1.26%(STS 316) and from 0.38%(PVC) to 0.65%(STS 316) in the reactor supplemented with disinfectant, respectively. No correlation was observed between disinfectant addition and biofilm density. With regard to the biofilm formation, little difference existed between PVC and STS 316. Yellow and red pigmented bacteria were the dominant expressions in bulk fluid, whereas non-pigmented bacteria were found dominant in the biofilm. Pink/red pigmented bacteria were found to be facultative anaerobic, while yellow pigmented bacteria and non-pigmented bacteria were found to be obligate aerobic.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.31.1-31.1
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• 2011

$Li_4Ti_5O_{12}$ is emerging as a promising material with its good structure stability and little volume change during the electrochemical reaction. However, its electrochemical performance is significantly limited by low electronic or ionic conductivity. In addition, high tap density is needed forim proving its volumetric energy density and commercialization. To enhance these properties, the spherical-like $Li_4Ti_5O_{12}$ particles were synthesized and carried out doping with yttrium. Prepared Y-doped $Li_4Ti_5O_{12}$ as a anode material showed great capacity retention rate of 92% (5C/0.2C), compared with no dope done. Consequently, it was found that Y doping into $Li_4Ti_5O_{12}$ matrix reduces the polarization and resistance on SEI layer during the electrochemical reaction.

• 수산해양교육연구
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• 제15권1호
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• pp.115-122
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• 2003

Generally, material for radiator of automobile is composed of Al-alloy, but part of radiator material is still composed of Cu. Specially, Al-alloy replaces Cu and Cu-alloy as cooling and heating system material for light weight. Therefore, galvanic electronic cell is formed between Al-alloy and Cu for automobile radiator material, and Al-alloy corrosion is accelerated. So, in this study, galvanic corrosion test of Al-alloy coupling with Cu was carried out in distilled water, tap water, polluted environment and non-freezing solution. And thus corrosion potential and galvanic currrent density of Al-alloy coupling with Cu is investigated.