• Korean Membrane Journal
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• 제6권1호
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• pp.61-69
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• 2004

Small angle light scattering (SALS) and field emission scanning electron microscope (FE-SEM) have been used to investigate the effects of alcohol on phase separation of chlorinated poly(vinyl chloride) (CPVC)/tetrahydrofuran (THF)/alcohol (9/61/30 wt%) solution during water vapor induced phase separation. A typical scattering pattern of nucleation & growth (NG) was observed for all casting solutions of CPVC/THF/alcohol. In the case of the phase separation of CPVC dope solution containing 30 wt% ethanol or n-propanol, the demixing with NG was observed to be heterogeneous. Meanwhile, the phase separation of CPVC dope solution with 30 wt% n-butanol was found to be predominantly homogeneous NG. Although the different phase separation behavior of NG was observed with types of alcohol additives, the resultant surface morphology had no remarkable differences. That is, even though the NG process by water vapor is either homogeneous or heterogeneous, this difference does not play a main role on the final surface morphology. However, it was estimated from the result of hydraulic flux that the phase separation by homogeneous NG provided the membrane geometry with lower resistance in comparison with that by heterogeneous one.

• 한국표면공학회지
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• 제49권3호
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• pp.238-244
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• 2016

Copper electrodeposition on AZ91 Mg alloy was studied in views of preferential deposition on ${\alpha}$- or ${\beta}$- phases and how to achieve uniform deposition over the entire surface on ${\alpha}$- and ${\beta}$-phases in a cyanide solution. The inhomogeneous microstructure of AZ91 Mg alloy, particularly ${\alpha}$- and ${\beta}$-phases, was found to result in non-uniform deposition of zincate layer, preferential deposition of zincate on ${\beta}$-phases, which leads to non-uniform growth of copper layer during the following electrodeposition process. The preferential depositions of zincate can be attributed to higher cathodic polarizations on the ${\beta}$-phases. Pin-hole defects in the copper electrodeposit were observed at the center of large size ${\beta}$-phase particles which is ascribed to gas bubbles formed at the ${\beta}$-phases. The activation of AZ91 Mg alloy in hydrofluoric acid solution was used to obtain uniform growth of zincate layer on both the ${\alpha}$- and ${\beta}$-phases. By choosing an optimum activation time, a uniform zincate layer was obtained on the AZ91 Mg alloy surface and thereby uniform growth of copper was obtained in a cyanide copper electroplating solution.

• 생물환경조절학회지
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• 제16권4호
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• pp.372-378
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• 2007

본 연구는 칼륨의 시비농도를 인위적으로 조절하여 잎들깨의 생장과 결핍증상 발현에 미치는 영향을 구명하고, 생육을 우수하게 유지할 수 있는 식물체 및 토양의 한계농도를 밝히기 위하여 수행하였다. 칼륨 결핍 증상은 노엽에서 시작되었으며, 노엽의 가장자리가 황변하고, 황변된 부위가 점차 갈색으로 변화되었으며, 갈변 후 괴사하였다. 칼륨 시비농도를 8mM까지 높일 경우 엽장과 줄기직경이 길거나 굵어졌으며, 생체중 및 건물중이 무거워지고, 엽록소 함량이 감소하였다. 생육이 우수하였던 K 8mM 시비구의 식물체당 건물중과 K 함량이 5.01g과 2.76%였으며, 생장억제를 방지하기 위해서는 1.7% 이상의 K 함량을 가져야 한다고 판단되었다. 칼륨을 8mM로 시비한 처리의 엽병추출액내 K 농도가 $12,289mg{\cdot}kg^{-1}$였고, 1:2로 추출한 토양농도가 $11.65mg{\cdot}L^{-1}$였으며, 엽병추출액은 $8,700mg{\cdot}kg^{-1}$이상, 토양용액은 $4.5mg{\cdot}L^{-1}$을 유지하도록 시비하여야 수량 감소를 방지할 수 있다고 판단되었다.

• 생물환경조절학회지
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• 제10권3호
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• pp.133-140
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• 2001

순환식 펄라이트재배에서 배액 재사용을 위한 양분흡수 모델링을 작성하고자 양액 농도(1.5, 1.8, 2.1, 2.4, 2.7 dS./m-1)를 달리하여 수행하였다. 생육 중기까지 전기전도도(EC) 수준에 따른 양액흡수량은 차이가 없었지만 중기 이후 EC가 높을수록 흡수량이 감소되는 경향을 보였다. N $O_{3-}$ N, P 및 K의 흡수량은 생육기간 동안 처리간 차이을 유지하였는데 N과 K는 생육 중기 이후 일정 수준을 유지하였으나 P는 생육기간동안 다소 증가되는 경향을 보였다. S의 흡수량은 생육 중기 이후 모든 처리에서 급격한 감소를 보였으며 생육 후기에는 처리간에 차이가 없었다. 오이의 무기이온 흡수율에서와 같이 흡수량에서도 EC간 차이를 보여 EC를 무기이온 흡수량을 추정하는 요소로 이용할 수 있을 것으로 생각되었다. 무기이온 흡수량은 모든 EC 처리간에 생육 초기에는 차이를 보이지 않았으나 생육중기 이후에는 뚜렷한 차이를 보인 후 생육 후기의 높은 농도에서 그 차이가 다소 감소되는 경향을 보였다. EC와 양액흡수량을 이용하여 무기이온별 흡수량을 예측하는 모델식을 작성하였으며 이를 이용한 실측치와의 비교는 신뢰구간 1%내에서 높은 정의상관을 보여 실제적인 적용이 가능할 것으로 생각되었다.

• 한국산림과학회지
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• 제90권1호
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• pp.74-82
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• 2001

Al과 Mn을 여러가지 농도로 조정한 배양액을 채운 포트에 소나무(Pinus densiflora) 2년생 묘목을 이식하여 수경재배법에 의해 90일간 온실내에서 육성한 후 소나무 묘목의 생장, 영양상태 및 가스교환속도에 미치는 Al과 Mn의 영향을 조사하였다. 배양액의 Al농도는 4수준(0, 10, 30, 60ppm)으로 처리하였으며, 이들 각각의 Al처리에 Mn농도를 3수준(0, 30, 60ppm)으로 처리하여 총 12처리구의 2요인배치법(two-factor design)의 실험을 실시하였다. Al과 Mn은 소나무 묘목의 건물생장에 상호작용효과(interaction effects)를 나타내지 않았으나, 소나무 묘목의 건물생장에 대한 Al과 Mn의 각각의 단독영향(main effects)은 유의적인 차이가 나타났다. 소나무 묘목의 건물생장은 Al은 10ppm이상, Mn은 60ppm의 농도에서 생장저하를 초래하였으며, 이는 소나무 묘목의 건물생장에 대한 Al의 독성이 Mn에 비해 클 수 있음을 시사한다. 뿌리의 암호흡속도는 Al의 경우 60ppm에서, Mn의 경우는 30ppm이상의 농도에서 저하하였다. 또한, 크로로필함량에 있어서는 Al의 영향은 인정되지 않았으나, 60ppm의 Mn처리구에서 낮아지는 경향을 보였다. 배양액의 Al과 Mn농도가 증가함에 따라서 소나무 묘목의 상대생장율(RGR) 및 순동화율(NAR)이 저하하였으며, 이는 광합성 효율의 감소가 원인으로 생각된다. 비록 본 연구결과는 수경재배법에 의하여 얻어진 결과이지만, 장래 우리나라에서 실제로 발생할 수 있는 산성강하물에 의한 수목피해 예측 및 산성화된 토양의 임지에서도 이와 유사와 현상이 발생될 수 있음을 시사하고 있다.

• Journal of Ginseng Research
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• 제11권1호
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• pp.77-83
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• 1987

인삼사포닌이 벼(Oryza sativa L.)의 초기생장 및 발아에 미치는 영향을 조사하기 위하여, 볍씨를 $10^{-4}$% 사포닌용액에 침종시킨 후, ${\circ}C$에서 성장시켰다. 인삼사포닌용액($10^{-4}$%)에 60시간 동안 침종한 볍씨(시험군)는 증류수에 침종한 대조군에 비해 시간에 따른 생장이 촉진(약 10%)되었으며, 잎의 출현시기도 통계적으로 빨랐다. 또한, 볍씨 발아시의 주요효소인 amylase의 활성을 12, 24, 48, 72시간 침종한 볍씨파쇄액에서 조사한 결과, 시험군이 대조군에 비해 각각 1.27, 1.58, 1.69, 1.49배 촉진되었으며, in viro 실험의 결과도 $10^{-5}$%사포닌 존재하에서 대조군에 비해 활성이 약 30% 증가하였다. 이상의 결과로 부터 인삼사포닌의 벼의 발아에 기능하는 amylase를 활성화하여, 벼의 발아 및 초기생장을 촉진하는 것으로 해석된다.

• 대한기계학회논문집A
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• 제25권5호
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• pp.772-778
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• 2001

In this study, corrosion fatigue characteristics of 12Cr alloy steel were investigated in 3.5wt.% NaCl solution of 150$^{\circ}C$ and 4.5bar. Behavior of corrosion fatigue cracks was measured by the indirect compliance method and compared with the results in distilled water and in air. 1) 12Cr alloy steel was susceptible to temperature. Its susceptibility was increased as the temperature was increased. 2) The crack growth characteristics of 12Cr alloy steel in distilled water were similar to 3.5wt.% NaCl solution. 3) The temperature of solution affects to the crack growth characteristics of 12Cr alloy steel. In corrosion solutions of 4.5bar, 150$^{\circ}C$, fracture surfaces of corrosion fatigue crack growth at a/W=0.3 was showed the trans-granular fracture suface. As the crack grew up, it was changed to inter-granular type. In condition of high temperature, The crack growth behaviors of 12Cr alloy steel were remarkable.

• 오토저널
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• 제8권1호
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• pp.40-51
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• 1986

A study has been made of the corrosion fatigue of high strength low alloy steel in 3.5% NaCl solution under tension stress for solution temperature being 25.deg. C, 55.deg. C and 85 .deg. C. The main results obtained are as follows; 1) The corrosion fatigue crack growth rate curve could be divided into the First Region, the Second Region and the Third Region. 2) The corrosion fatigue crack growth rates in the First Region and the Second Region were Arrhenius temperature-dependent in this test range. The apparent activation energies for the corrosion fatigue cack growth rate were found to be 2000cal/mol in the First Region and 3700 cal/mol in the Second Region. 3) Hematite (Fe$_{2}$O$_{3}$) as the hexahedral crystal and magnetite (Fe$_{3}$O$_{4}$) as the octahedral crystal were observed in the corrosion products on the corrosion fatigue fracture surface at 85.deg. C and the anode fusion seem to be generated in the crack tip region at high temperature. 4) The complex environment effect ratio which was defined by the ratio of fatigue crack growth rate in corrosion environment to that in air might be considered not only a criterion estimating the effect of environment quantitatively but also an important parameter in the selection of the design stress for the fail safe design. The complex environment effect was not greater than ten in this test.

• Food Science and Biotechnology
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• 제17권4호
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• pp.878-882
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• 2008

The efficacy of citric acid-aqueous chlorine dioxide ($ClO_2$) treatment of radish seeds artificially contaminated with Escherichia coli was studied. Radish seeds were inoculated with E. coli. Following inoculation, samples were stored at $4^{\circ}C$ and soaked in citric acid or aqueous $ClO_2$ for 10 min. The treatment of radish seeds using 200 ppm aqueous $ClO_2$ solution caused a 1.5 log CFU/g reduction in the population of E. coli. Compared to the aqueous $ClO_2$ treatment, soaking radish seeds in 2.0% citric acid solution for 10 min was more effective in reducing E. coli populations on radish seeds. The efficacy of spray application of chlorine (100 ppm) or 0.5% citric acid to eliminate E. coli during the germination and growth of radish was investigated. Radish seed inoculated with E. coli was treated for the duration of the growth period. Although it resulted in a decrease in the E. coli population, the spray application of 100 ppm chlorine during the growth period was not significantly effective. In contrast, the combined treatment of seeds using 200 ppm aqueous $ClO_2$ and treatment of sprouts with 0.5% citric acid solution during sprout growth was hardly effective in eliminating E. coli.

• 생물환경조절학회지
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• 제14권3호
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• pp.174-181
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• 2005

Experiments were carried out to develop an optimal nutrient solution for the single-stemmed rose (Rosa hybrida L.) 'Red velvet' in a closed aeroponic system. Plants were grown in 1/3, 1/2, 1, or 3/2 strength of the nutrient solution of National Horticultural Research Station in Japan (NHRS). Significantly less changes of pH and EC ($dS{\cdot}m^{-1}$) in the drainage were observed in 1/2 strength treatment as compared to other treatments. The $NO_3-N$, K, Ca, and Mg concentrations in the drainage solution of 1/2 strength treatment were maintained at optimal levels. These results indicated that the rose uptakes of both nutrients and water was more stable than those in other concentration. The concentration of macronutrients in nutrient solution were adjusted based on the ratio of nutrient:water (n/w) taken up by plants grown in the 1/2 strength solution. The composition of the new solution (classified the University of Seoul (UOS) solution) was as follow; $NO_3-N$ 8.8, $NH_4-N$ 0.67, P 2.0, K 4.8, Ca 4.0, Mg 2.0 $me{\cdot}L^{-1}$. To further evaluate new solution on crop growth, the rose 'Red Velvet' was grown again in l/2, 1, and 2 strength UOS solution to compare with 1.0 strength PBG (proefstion voor bloemisterij en glasgroenpe) solution. Overall the plant growth, including the stem length and number of five-leaflet leaves was higher in 1.0 strength of UOS solution than other treatments. Results presented in this study indicate that the nutrients in the UOS solution are well balanced for the single-stemmed rose in the closed aeroponic system.