• 콘크리트학회논문집
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• 제22권2호
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• pp.219-228
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• 2010

하수도, 오 폐수, 토양 속, 지하수 및 해수 등의 환경에 건설되는 콘크리트 구조물은 산 및 황산염에 노출되어 있다. 이 같은 산 및 황산염 침투로 포틀랜드 시멘트 중의 수화생성물과 산 및 황산염 이온이 반응하여 팽창 수화물을 생성함으로써 콘크리트에 팽창 및 균열을 발생시켜, 결국 콘크리트 매트릭스에 손상을 일으킨다. 따라서 이 연구의 목적은 콘크리트의 황산 및 황산염 침투 저항성에 미치는 광물질 혼화재의 영향을 평가하여, 황산 및 황산염 침투에 대한 고저항성 콘크리트를 제시하는 것이다. 이를 위하여 광물질 혼화재의 형태 및 비율을 변화시킨 OPC, 2성분계 및 3성분계의 3가지 종류의 시멘트를 사용하여 물-결합재비 32% 및 43%인 콘크리트를 제조하였다. 제작된 콘크리트 시편은 민물, 5% 황산, 10% 황산나트륨 및 10% 황산마그네슘 용액에 재령 28, 56, 91, 182 및 365일 동안 각각 침지시켰다. 콘크리트의 황산 및 황산염 침투 저항성을 평가하기 위하여 외관변화 관찰과 압축강도 비 및 질량 변화율을 측정하였다. 그 결과, 광물질 혼화재를 혼입한 콘크리트의 황산 및 황산나트륨 침투에 대한 저항성은 OPC 콘크리트 경우 보다 훨씬 우수한 것으로 나타났으나, 황산마그네슘의 경우 비결합재질의 규산마그네슘수화물(M-S-H)의 형성으로 광물질 혼화재를 혼입한 콘크리트가 OPC 콘크리트보다 불리한 것으로 나타났다.

• 생명과학회지
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• 제33권4호
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• pp.334-342
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• 2023

가자미식해에서 분리된 유산균 40종은 Lactobacillus plantarum spp., Leuconostoc mesenteroides spp., Lactobacillus brevis spp., and Weisella paramenteroides spp.로 확인됐으며, 40종 중 10종을 선별해 검사에 사용했다. 본 연구에서는 가자미식해에서 분리된 유산균을 프로바이오틱스로 활용하기 위해 산 및 인공위액 저항성, 담즙산 저항성, 자가 응집성, 공동 응집성, 세포 표면 소수성 등의 프로바이오틱 연구를 수행하였다. 분리한 유산균주는 산성 및 인공 위액에 대해 저항성을 보여 높은 생존율을 나타내었으며, L. plantarum GS11이 가장 뛰어난 저항성을 보였다. 또한 담즙산 저항성 측정 결과 모든 유산균주가 10⁸~10⁹ log CFU/ml의 생균수로, 100% 이상의 생존력을 보여주었다. 그리고 세포 표면 부착능을 간접적으로 측정하기 위해 응집력 평가를 한 결과, autoaggregation 능력을 46% 이상 나타내었다. 세포 표면 소수성 평가를 위해 Xylene 부착능을 측정한 결과 분리된 유산균주에서 32.2%의 소수성을 가지는 B. subtilis 보다 더 뛰어난 세포 부착률을 보여주었다. 이와같이 유산균은 프로바이오틱스로 활용될 만한 유의미한 결과를 보였으며, L. plantarum GS12와 L. plantarum GS13을 제외한 유산균에서 항균 활성이 나타났다. 따라서 가자미 식해에서 분리된 유산균은 다양한 프로바이오틱스 특성을 가진 프로바이오틱스로 활용할 수 있을 것으로 판단되어진다.

• 해양환경안전학회지
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• 제12권2호
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• pp.89-98
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• 2006

이 연구는 해산어 양식장 환경을 재현한 해양 microcosm을 이용하여, 양식장에서 빈번히 사용하고 있는 옥소린산에 대한 미생물이 나타내는 항생제 내성획득에 관해 알아보고자 하였다. 옥소린산 처리 전과 후의 세균상을 비교한 결과, 비브리오 과 세균은 실험기간 전반에 걸쳐 65-75% 정도로 우점하였으며, 그람양성세균인 Micrococcos sp. 와 Bacillus sp. 는 옥소린산 처리 기간 중에 출현 빈도가 증가하였다. 해산어양식 환경에서 세균의 ETS 활성은옥소린산 처리 기간중 42-67%로 줄어들었지만, 옥소린산의 처리가 종료된 후에 세균은 다시 회복되었다. 해산어 양식장에서 옥소린산의 빈번한 사용은 옥소린산에 대한 세균의 내성을 증가시키는 것으로 관찰되었다.

• The Plant Pathology Journal
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• 제29권3호
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• pp.305-316
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• 2013

Non-protein amino acid, ${\beta}$-amino-n-butyric acid (BABA), has been involved in diverse physiological processes including seedling growth, stress tolerance and disease resistance of many plant species. In the current study, treatment of kimchi cabbage seedlings with BABA significantly reduced primary root elongation and cotyledon development in a dose-dependent manner, which adverse effects were similar to the plant response to exogenous abscisic acid (ABA) application. BABA was synergistically contributing ABA-induced growth arrest during the early seedling development. Kimchi cabbage leaves were highly damaged and seedling growth was delayed by foliar spraying with high concentrations of BABA (10 to 20 mM). BABA played roles differentially in in vitro fungal conidial germination, mycelial growth and conidation of necrotroph Alternaria brassicicola causing black spot disease and hemibiotroph Colletotrichum higginsianum causing anthracnose. Pretreatment with BABA conferred induced resistance of the kimchi cabbage against challenges by the two different classes of fungal pathogens in a dose-dependent manner. These results suggest that BABA is involved in plant development, fungal development as well as induced fungal disease resistance of kimchi cabbage plant.

• 한국치위생학회지
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• 제10권5호
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• pp.947-953
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• 2010

Objectives : The purpose of this investigation was to evaluate the remineralization and acid resistance in fluoride varnish by Micro-computed tomography (micro CT). Methods : Specimens of bovine teeth enamel were embedded in resin, polished and randomly divided into 3 groups (a control group, a NaF solution group, a fluoride varnish group). Each group has 3 specimens that was standardized according to Vickers hardness number (VHN). Specimens were immersed in demineralization solution for 72 hours. The control group had no treatment, the NaF solution group was treated by a 5% NaF solution for 4 minutes, and the fluoride varnish group was treated by a fluoride varnish for one hour. All specimens were subjected to a chemical pH cycling method for 14 days. After a chemical pH cycling method, the density were measured using micro CT. Then, specimens were immersed in each demineralization solution for 72 hours. After demineralization processed, the density were measured using micro CT. Results : 1. The density was significantly higher in the fluoride varnish and 5% NaF solution group than that of the control group after 14 days cycling (p<0.05). And the density value of the fluoride varnish group was higher than that of the 5% NaF solution, with no significant difference. 2. The differences of density after acid resistance treatment were statistically significant among 3 groups(p<0.05). Conclusions : It is suggested that fluoride varnish showed the remineralizing effect and acid resistance effect on the enamel, and micro CT could be used to evaluate the change of enamel lesion.

• 대한소아치과학회지
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• 제24권2호
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• pp.405-421
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• 1997

The main purpose of this study was to evaluate the acid resistance and antimicrobial effect of fluoride-laser combined application. Recently extracted third molars were used. $5{\times}3mm$ of the buccal and lingual specimens were exposed and incipient artificial carious lesions were formed by keeping them in the artificial cariogenic solution for 5 days. They were divided into five groups and treated with fluoride and laser according to the predetermined regimen. The acid resistance was compared between groups by chemical quantitative analysis of the calcium and phosphorous released into the test solution after single or combined application of fluoride and laser. The antimicrobial effect of each group was analyzed by counting the number of colony forming units after microbial incubation. The results from the present study can be summarized as follows; 1. Experimental groups showed lower values in calcium and phosphorous contents as well as in $CFU/m{\ell}$(colony forming units) than control group. Combined application groups showed lower values than single application groups. 2. Acid resistance and antimicrobial effect by fluoride and laser treatment were confirmed in this study. 3. Based upon the above-mentioned results of this study, it can be assumed that the use of laser-fluoride combined application may provide the child and adolescent patient population with antimicrobial effect as well as acid resistance. Further studies using various materials and experimental conditions are being encouraged.

• 한국재료학회지
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• 제20권2호
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• pp.51-54
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• 2010

Transparent conductive films of single wall carbon nanotube (SWCNT) were prepared by spray coating method. The effect of acid treatment on the SWCNT films was investigated. The field emission scanning electron microscope (FESEM) shows that acid treatment can remove dispersing agent. The electrical and optical properties of acid-treated films were enhanced compared with those of as deposited SWCNT films. Nitric acid ($HNO_3$), sulfuric acid ($H_2SO_4$), nitric acid:sulfuric acid (3:1) were used for post treatment. Although all solutions reduced sheet resistance of CNT films, nitric acid can improve electrical characteristics efficiently. During acid treatment, transmittance was increased continuously with time. But the sheet resistance was decreased for the first 20 minutes and then increased again. Post-treated SWCNT films were transparent (85%) in the visible range with sheet resistance of about $162{\Omega}/sq$. In this paper we discuss simple fabrication, which is suitable for different types of large-scale substrates and simple processes to improve properties of SWCNT films.

• The Plant Pathology Journal
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• 제19권1호
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• pp.19-23
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• 2003

Turnip crinkle vims (TCV) inoculation onto resistant Arabidopsis ecotype Dijon（Di-17) leads to a hypersensitive response (HR) on the inoculated leaves. A dominant gene, HRT, which confers an HR to TCV, has been cloned from Di-17 plants by map-based cloning. HRT is a LZ-NBS-LRR class resistance gene and it belongs to a small gene family that includes RPP8, which confers resistance to Peronospora parasitica Emco5. Outside of the LRR region, HRT and RPP8 proteins share 98% amino acid identity while their LRR regions are less conserved (87% identity). HRT-transformed Arabidopsis plants developed an HR but generally remained susceptible to TCV due to a dominant RRT allele, which is not compatible with resistance. However, several transgenic plants that over-expressed HRT much higher than Di-l7 showed micro-HR or no HR when inoculated with TCV and were resistant to infection. Both the HR and resistance are dependent on salicylic acid but independent of NPRI, ethylene, or jasmonic acid. Arabidopsis plants containing both TCV coat protein gene and HRT developed massive necrosis and death in seedlings, indicating that the TCV coat protein is an avirulence factor detected by the HRT.

• 한국미생물·생명공학회지
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• 제5권1호
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• pp.5-12
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• 1977

As a basic study for the application of the spore-tearing lactic acid bacteria to foods, the effects of the sporulating conditions on the growth and sporogenesis were studied were observed. The results obtained are as follow. 1. All carbohydrates added to sporulation media except dextrin decreased the sporulation rate and the thermal resistance of spores. Dextrin stimulated the growth, however, there in no effect on the thermal resistance. 2. As nitrogen source, the protein hydrolysates such as peptone, casamino acid were effective to obtain were spores of the increased thermal resistance. 3. Ca$\^$＋＋/, Mn$\^$＋＋/ of the metal ions added to casamino acid containing medium validly increased the total growth, sporulation rate and thermal resistance. Its optimum concentration was 40 ppm each. 4. Biotin of vitamines had an effect on the total growth, sporulation and thermal resistance of spores. Its optimum concentration was 30${\gamma}$/ml. 5. The resistant spores required the adequate maturation period, more than 36 hours, sufficient aeration. and optimum temperature, 37∼45$^{\circ}C$.

• 미생물학회지
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• 제6권1호
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• pp.1-5
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• 1968

This experiment was undertaken the purpose of investigating the difference of the content of free amino acids in the diseased and healthy leaves of the resistance and susceptible rice varieties, to blast by means of paper chromatography. The results obtained are summarized as follows. (1) In the healthy and diseased leaves, the former was founded nine to tell sorts of free amino acids and later was observed eleven. In the both of leaves, alanine and valine were contained in larger amount, and aspartic acid, glycine and arginine were found relatively less in general. (2) In the diseased leaves, the amino acids were increased in quantity, especially glutamine and aspartic acid were remarkable, and cystine were found only in the diseased ones. (3) It seems to that the health leaves in all varieties were observed the amino acid contents, in notably increase and decrease, but in the diseased ones were not changed in amount. Tatacho, susceptible variety was more contained the amount of glutamine and aspartic acid than Zenith, resistance one.