• KSBB Journal
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• v.24 no.5
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• pp.432-438
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• 2009

Here, we demonstrated simple nucleic acid, RNA, concentration method using polymer micro chip containing glass bead ($100\;{\mu}m$). Polymer micro chip was fabricated by PDMS ($1.5\;cm\;{\times}\;1.5\;cm$, $100\;{\mu}m$ in the height) including pillar structure ($160\;{\mu}m\;(I)\;{\times}\;80\;{\mu}m\;(w)\;{\times}\;100\;{\mu}m\;(h)$, gap size $50\;{\mu}m$) for blocking micro bead. RNA could be adsorbed on micro glass bead at low pH by hydrogen bonding whereas RNA was released at high pH by electrostatic force between silica surface and RNA. Amount of glass beads and flow rate were optimized in aspects of adsorption and desorption of RNA. Adsorption and desorption rate was measured with real time PCR. This concentrated RNA was applied to amplification micro chip in which NASBA (Nucleic Acid Sequence Based Amplification) was performed. As a result, E.coli O157 : H7 in the concentration of 10 c.f.u./10 mL was successfully detected by these serial processes (concentration and amplification) with polymer micro chips. It implies this simple concentration method using polymer micro chip can be directly applied to ultra sensitive method to measure viable bacteria and virus in clinical samples as well as environmental samples.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.925-927
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• 2012

On-site diagnosis applied to soil having a symptom of yellowing and whitening in cucumber leaf and stem. Soil pH determined 4.2 by methods of on-site analysis and 4.5 by soil test analysis. High aluminum in soil solution extracted with water saturation was detected. Leaf and stem tissue were abundant in Al content but not in Ca. Also, N content of leaf and stem was low compared to normal N ranges. This symptom of cucumber assumed to be from the Al and nitrous acid gas toxicity by low soil pH and Eh. Conclusionally, symptom in leaf and stem of cucumber was alleviated and cucumber normally recovered during cultivation period by applying calcium hydroxide solution to correct soil pH up to 6.5. These results showed that low soil pH resulted in aluminum toxicity and N deficiency to plant growth in on-site farming.

• Resources Recycling
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• v.28 no.3
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• pp.15-20
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• 2019

The recovery of struvite using nitrogen and phosphorus in wastewaters is useful for prevention of eutrophication and use as fertilizer, but there are theoretical and technical issues to be resolved. Through the detailed literature review, this study discusses the possible reasonable prediction of struvite formation reaction by setting a feasible reaction equation with some theoretical considerations. In a technical aspect, the purity of struvite in solid precipitates can be promoted by excluding Ca in an effective way. As for the struvite reaction prediction issue, selection of proper equilibrium reaction as well as its reaction equilibrium coefficient is significant in the neutral and basic pH regions. The equilibrium reaction agrees well with the experimental batch test results. Considering the charge balance of the ions, the pH drop along struvite formation in a diluted solution can be predicted. Also, improvement of struvite purity through elimination of Ca can be expected by providing a highly concentrated ${NH_4}^+-N$ relative to ${HPO_4}^{2-}-P$ because ${NH_4}^+$ can enhance the thermodynamic driving force toward favorable struvite formation. Even though the phosphate reacts rapidly with Ca to form a solid precipitate, the thermodynamic driving force due to the high ${NH_4}^+$ activity can dissociate the phosphate-calcium precipitates and produce struvite.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.4
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• pp.485-490
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• 2014

The aim of this study was to investigate the hypocholesterol effects of Opuntia humifusa extract in hypercholesterolemic rats. Rats (8-week-old, male) were randomly divided into four groups (n=4) as follows: N-control, normal diet; H-control, hypercholesterolemic diet; OH-1, 2% O. humifusa extract-supplemented hypercholesterolemic diet; OH-2, 4% O. humifusa extract-supplemented hypercholesterolemic diet. After 4 weeks, we observed that hypercholesterolemia induced significant increases in serum lipids (total cholesterol and LDL-cholesterol), hepatic lipids (total cholesterol and triglyceride), and hepatic function parameters (ALT, alanine aminotransferase; AST, aspartate aminotransferase) (P<0.05). Treatment with O. humifusa extract for 2 weeks normalized these indexes up to the levels of normal rats. O. humifusa extract tended to increase fecal lipid (H-control: 142.74 mg/day vs. OH-1: 214.05 mg/day; OH-2: 200.95 mg/day, P<0.05) and bile acid (H-control: 37.07 ${\mu}M/day$ vs. OH-1: 47.23 ${\mu}M/day$, OH-2: 47.93 ${\mu}M/day$, P<0.05) contents of hypercholesterolemic rats. We concluded that oral administration of O. humifusa extract effectively improved cholesterol metabolism in a hypercholesterolemic animal model induced by hypercholesterol diet.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.161-162
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.969-970
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.343-344
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• 2013

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.729-735
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• 2009

In this study, it is experimentally verified a feasibility of the wasted phosphogypsum ($CaSO_4/H_2O$) that is a byproduct from the phosphoric acid process of manufacturing fertilizers can be applied as an admixture in slag cement. For the test, phosphogypsum is modified as dihydrate, hemihydrate, type III anhydrite, and type II anhydrite, and then chemical characteristics and mechanical properties of various slag cements containing above mentioned gypsum materials were analyzed. The test results show that the gypsum made at high temperature has better quality with decrease of water-soluble phosphoric acid ($S-P_2O_5$) which has an effect on the quality of cement. And type II anhydrite shows superior quality in terms of drying shrinkage and the compressive strength of cement paste with hemihydrate at 56 days is higher than other gypsum material.

• Journal of Animal Science and Technology
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• v.52 no.2
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• pp.111-116
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• 2010

This study was conducted to determine the effects of different feeding levels on the number of fecal lactic acid-producing bacteria and fecal pH in horses. In Exp. 1, 6 female cross-bred horses ($332.4{\pm}50.4\;kg$, 5 year old) were fed 2% hay or 2% concentrates of BW for 30 d, and the number of fecal Lactobacilli and Streptococci was measured. For Exp. 2, 5 castrated Thoroughbred ($474.5{\pm}64.6kg$, 4 year old) and 5 female cross-bred horses ($343.6{\pm}56.3\;kg$, 5 year old) were allotted to high- or low-concentrates diets (5 levels) for 30 d in a $5{\times}5$ Latin square design, and the fecal pH was assessed. In Exp. 3, 3 castrated Thoroughbred ($482.6{\pm}53.3\;kg$, 4 year old) were fed high- or low-alfalfa hay diets (3 levels) for 30 d in a $3{\times}3$ Latin square design, and the fecal pH was measured. Feeding high-concentrates diets increased (P<0.05) the number of fecal lactic acid-producing bacteria (Lactobacilli and Streptococci) and decreased (P<0.01) the fecal pH. Feeding alfalfa hay with high-concentrates diet (2% alfalfa hay + 1% concentrates of BW) decreased (P<0.01) the fecal pH. These results showed that feeding high-concentrates diets increased lactic acid-producing bacteria in the large intestine and decreased the intestinal or fecal pH causing colic or laminitis, indicating that the proper fiber/concentrates (1:1) should be maintained in horses.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.275-277
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• 2007

유리를 기판으로 하는 superstrate pin 비정질 태양전지에서 전면투명전도막(TCO)과 p-layer의 계면이 태양전지의 효율을 내는데 가장 큰 기여를 한다. 전면투명전도막(TCO)으로 현재 일반적으로 사용되는 ZnO:Al는 $SnO_2:F$ 보다 전기,광학적으로 우수하고, 안개율(Haze)높으며, 수소 플라즈마에서의 안정성이 높은 특정을 갖고 있다. 그래서 박막 태양전지 특성향상에 매우 유리하나, 태양전지로 제조했을 때, $SnO_2:F$보다 충진율(Fill factor:F.F)과 V_{\infty}$ 가 감소한다는 단점을 가지고 있다. 본 실험실에서는 $SnO_2:F$의 F.F가 72%이 나온 반면 ZnO:Al의 F.F은 68%에 그쳤다. 이들 원인을 분석하기 위해 TCO/p-layer의 전기적 특성을 알아 본 결과, $SnO_2:F$보다 ZnO:Al의 직렬저항이 높게 측정되었다. 이러한 결과를 바탕으로 p-layer 에 R={$H_2/SiH_4$}=25로 변화, p ${\mu$}c$-Si:H/p a-SiC:H 로 p-layer 이중 증착, p-layer의 boron doping 농도를 증가시키는 실험을 하였다. 직렬저항이 가장 낮았던 p ${\mu$}c$-Si:H/p a-SiC:H 로 p-layer 이중 증착에서 Voc는 0.95V F.F는 70% 이상이 나왔다. 이들 각 p층의 $E_a$(Activation Energy)를 구해본 결과, ${\mu$}c$-Si:H의 Ea 가 가장 낮은 것을 관찰 할 수 있었다.