• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.924-927
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• 2003

This study was conducted to investigate the application of bifidobacteria on kimchi. Among several Bifidobacterium species, we selected Bifidobacterium lactis (DSM 10140), which is resistant to oxygen, acid and salt. Bifidobacterium lactis was cultured in a supplemented deMan, Rogosa and Sharpe (SMRS) medium under aerobic conditions. Its acid-tolerance and salt-tolerance were pH 3.0 and 3.5% (NaCl), respectively. The viability of Bifidobacterium lactis added to kimchi was confirmed by PCR, using specific primers on Bifidobacterium lactis. In sensory evaluation, kimchi containing Bifidobacterium lactis showed similar scores in overall acceptability with the control kimchi. Consequently, these results showed that it would be possible to prepare functional kimchi using Bifidobacterium.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.808-811
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• 2007

본 연구는 3톤/일급 이하 가스화 용융로에서 $1,400{\sim}1,500^{\cdot}C$, $7.5{\sim}8.0$ kg/$cm^2$의 안정적인 운전조건일 때, 시료로 Kideco 탄을 사용하고 이때 발생한 슬랙의 특성 및 슬랙의 재활용을 위한 벽돌제조 특성을 고찰하였다. 발생된 슬랙은 $Fe_2SiO_4$와 $SiO_2$가 결정상태로 일부 존재하거나, 중금속들이 결합되어 엉킨 구조인 비결정상태의 치밀한 형태로 이루어져 있었으며, 잔존탄소 함량이 0.06%로 미량 존재하였다. 또한 슬랙에는 중금속 농도가 Kideco탄보다 고농도로 존재하지만, 용출되는 중금속의 농도는 매우 낮아 환경적으로 안정한 물질로서 재활용이 가능한 특성을 지니고 있다. 슬랙 첨가 점토벽돌의 적합성을 평가하기위해 슬랙을 0%, 10%, 30% 첨가하여 벽돌을 제조하고 KS 산업규격에 따라 시험을 실시하였다. 분석결과 슬랙을 첨가할수록 제조한 벽돌의 흡수율이 낮아져 기존 제품에 비하여 우수한 것으로 측정되었다. 또한 압축강도와 휨강도는 기존 제품의 $80{\sim}86%$ 정도인 것으로 측정되었지만 KS 산업규격의 기준치보다 높은 수치를 나타내였고, 내산성, 내알칼리성, 열충격강도 또한 양호한 것으로 나타나, 슬랙을 이용하여 벽돌로 재활용하여 충분히 사용 가능한 것으로 확인되었다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.132-132
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• 1999

카본 박막은 내마모성, 내산성, 윤활성 및 높은 경도를 가지고 있어, 경질 박막 및 기능성 박막으로 주목을 받고 있으며 그 응용 분야가 매우 크다. 본 연구는 전자빔(Electron Beam)을 카본 grain을 증발시킴과 동시에 아르곤 보조 이온빔을 조사시켜 이온에너지에 따른 박막의 물성변화를 관찰하였다. 특히 본 연구에서 이용한 이온빔 증착 장치의 장점은 이온 충돌 에너지의 조절이 가능하다는 것이다. 카본 박막의 제조는 이온빔이 증착된 고진공 증착 장치를 이용하였고 이원빔원으로는 Oxford Applied Research 사의 RF 방전형 이온빔을 이용하였다. 배기장치는 유회전펌프와 터보펌프를 사용하였다. 기판은 홀더에 장착하기 전에 전처리를 거친 후 용기 내에서 이온빔에 의해 2차 청정을 하였다. 빔전압이 500V, 빔 전류는 4mA/cm2 및 RF power를 400W로 하여 기판 청정을 거친 후 전자빔을 이용하여 흑연을 증발시켜 박막을 제조하였다. 이때 이온빔 전압을 100~500V, RF power를 400~550W 으로 조절하였다. 카본 grain을 Si 및 Slide Glass 기판위에 1$\AA$/sec의 증착율을 유지하면서 증착하였다. 카본 박막의 박막은 평균두께는 0.3~0.4$\mu\textrm{m}$이며 SEM을 이용하여 단면을 관찰하였다. 라만 분광분석을 통하여 비정질 카본 박막의 결합특성을 조사하였고 scratch tester를 이용하여 박막의 밀착력을 관찰하였다. 그리고 카본 박막의 전도도 특성을 알고자 비저항을 측정하였으며, 박막의 성분 분석을 위한 AES 분석을 하였다. 1)AES 결과:표면에서와 박막 내부에서는 불순물인 산소나 질소의 함량이 거의 존재하지 않음을 관찰하였다. 2)경도:1,000~1,400kg/mm2 3)라만 분광 분석:300V의 이온 에너지를 분기로 박막 구조의 변화에 의한 스팩트럼의 변화를 보였다. 4)비저항:10-2~10-1$\Omega$.cm

• Food Science of Animal Resources
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• v.33 no.4
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• pp.522-530
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• 2013

The ability of probiotics to adhere to the intestinal epithelium likely plays an important role in their colonization of the gastrointestinal tract. Here, we performed high-throughput screening (HTS) for suitable characteristics of potential probiotic bacteria using attachment and colonization ability through a C. elegans surrogate in vivo model. A total of 100 strains of lactic acid bacteria (LAB) isolated from infant feces were subjected to the colonization assay using C. elegans intestine. Based on colonization ability, we showed that nine isolates have a high attachment ability during whole experimental periods (up to 168 h), compared to Lactobacillus rhamnosus strain GG as a control. Also, through the use of an in vitro cell attachment model, nine isolates revealed highly binding activity to the mucus layer. Next, the selected 9 isolates were assayed for their survival ability when exposed to acidic and bile conditions as well as cholesterol reduction and the utilization of prebiotic substrates. As a result, the isolated nine strains were determined to be highly resistant to acid and bile conditions. In addition, they have significant activity for the reduction of cholesterol and utilization of several prebiotic substrates as a carbon source. Finally, the selected nine strains were identified by either L. rhamnosus or L. plantarum (4 strains for L. rhamnosus and 5 strains for L. plantarum, respectively). Taken together, we propose that the direct colonization of probiotics using C. elegans may be applicable to the rapid screening of valuable probiotic strains in vivo.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.121-129
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• 2008

Environmental friendly UV-curable coatings, having excellent hardness, gloss, mar and chemical resistance, are commonly used for the wooden flooring coatings. Especially epoxy acrylate oligomers are chosen for the wooden flooring coatings, due to their thermal stability and fast curing. In this study, we investigated the effect of the acrylate functionality on the thermal stability and surface hardness. The thermal degradations of monomers, oligomer, photoinitiator and formulated coatings with different acrylate functionality were measured using a thermogravimetric analysis (TGA). And the surface hardness was also measured with a pendulum hardness tester to compare relationship between the thermal stability and the physical property. The cured coatings became thermally stable by crosslinking during UV-curing. Both the thermal stability and surface hardness of cured coatings were improved with increasing acrylate functionality.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.377-398
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• 1999

Calcium fluoride, created by topical fluoride application, is the reservoir for fluoride ion regulated by pH in the oral environment. Therefore, the amount and the maintenance of calcium fluoride have an important role in preventing dental caries. The aim of this study is to evaluate the effect of Nd:YAG laser irradiation on the generation of calcium fluoride and the acid resistance of tooth enamel. The bovine anterior permanent teeth were prepared (n=276), and divided into following groups : no treatment (control) fluoride application alone, laser irradiation alone, laser irradiation after fluoride application, and fluoride application after laser irradiation. And each group was subdivided based on the application time of 1.23% acidulated phosphate fluoride (APF) (5 min and 30 min) and the irradiation energy of Nd:YAG laser ($20J/cm^2\;and\;40J/cm^2$). In case of fluoride application, each group was divided according to KOH treatment. Twenty three treatment conditions were made for this experiment and twelve specimens were assigned to each treatment condition. In each treatment condition, ten specimens were used for chemical analysis and two specimens were observed under SEM. In groups without treating KOH, fluoride content and the depth of enamel dissolved were measured using enamel biopsy technique. In groups with treating KOH, the amount of calcium fluoride was measured by the treatment with 1 M KOH for 24 hours and enamel biopsy was performed after KOH treatment. The results were analyzed by the fluoride content and the depth of enamel dissolved by enamel biopsy, amount and thickness of calcium fluoride, and the surface structures of enamel. The results are as follows: 1. In groups without treating KOH, the fluoride content of removed enamel showed a positive relationship with the energy density of laser when the laser irradiated before fluoride application 2. In groups without treating KOH, the depth of enamel dissolved decreased more with the combined laser and fluoride treatment than with laser or fluoride treatment, except for the case of $20J/cm^2$ laser irradiation after 5 minute fluoride application (p<0.05). 3. The amount of calcium fluoride did not increased by laser treatment with no statistical significance(p>0.05). 4. The particle size of calcium fluoride increased in case of fluoride treatment after laser irradiation, compared with fluoride application alone. In case of laser treatment after fluoride application, the particle size of calcium fluoride increased and some of the particles fused as well. 5. There were no significant differences in the fluoride content of dissolved enamel between groups without treating KOH and control group, except for the case of laser irradiation after treatment of APF for 30 minutes (p>0.05). 6. In groups with treating KOH, depth of removed enamel in the groups of combined treatment with laser and fluoride was shallower than that in fluoride application groups (p<0.05). 7. In groups without treating KOH, the relationship between fluoride content and the depth of enamel dissolved showed more negative (Spearman correlation coefficient: -0.6281) than in groups with treating KOH (Spearman correlation coefficient: -0.3792). The greater amount of calcium fluoride could be found in case where there was a significant differences of the depth of enamel dissolved between groups with and without treating KOH. From these results, it can be concluded that laser seems to be a little effects on the amount of calcium fluoride formation, but has some effect on the lowering the solubility of calcium fluoride. As the combined treatment of laser and fluoride application showed more effective acid-resistant property, more extended recall period for fluoride application can be achieved with this combined treatment in the clinic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.206-207
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• 2005

Display 소재로서 유전체나 격벽재 실링재로 사용되고 있는 frit는 PbO를 주성분으로 갖는 유리가 사용되고 있다. PbO 성분이 함유된(50$\sim$85%) 구성소재는 최근 RoHS 나 WEEE 등의 환경규제 실행에 직면해 있으며, 대체재료의 개발을 위한 많은 연구가 진행되고 있다 PbO 성분을 대체할 성분으로는 $Bi_2O_3$ 계, BaO-ZnO 계, $P_2O_5$ 계 등의 성분이 주요성분으로 이루어져 있으며, PbO 성분을 함유한 유리의 저융점, 저유전율, 고 투과율, 내산성, 내전압, 팽창계수 matching 등의 특성들에 부합되는 재료를 개발하기 위해 많은 노력을 기울이고 있다. 본 연구에서는 SnO-$P_2O_5$ 계 유리 조성을 선택하여 $R_2O_3$의 치환 및 용융분위기의 조절에 따른 저융점 유리로서의 특성과 효과에 대하여 고찰하였다.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.5
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• pp.19-27
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• 2008

This study was performed to evaluate the compressive strength and acid-resistant of polymer concrete using redispersible polymer powder(RPP) and blast furnace slag powder(BSP). Material used were ordinary portlant cement, recycled coarse aggregate, natural fine aggregate, redispersible polymer powder and blast furnace slag powder. The main experimental variables were the substitution ratio of redispersible polymer powder and blast furnace slag powder, when the substitution ratios of RPP were 0, 1, 2, 3, 4, 5 and 6%, and those of BSP were 10%. The compressive strength and acid-resistant of polymer concrete using RPP and BSP were compared with those of ordinary concrete(Basis). When the substitution ratio of RPP was 1%, at age of 28 days, the compressive strength were more higher than those of Basis by 24%, and it was decreased with increasing the RPP content, respectively. Also, the water absorption ratio was decreased with increasing the RPP content. But, the acid-resistant was improved with increasing the RPP content.

• Magazine of the Korea Concrete Institute
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• v.8 no.1
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• pp.138-144
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• 1996

At present, waterproof is absolutely needed to minimize the carbonation of bridge decks in Kor ea. In this research indoor experiments for penetrative waterproof admixture out of available methods are carried out to evaluate the resisting characteristics against natural arid artificial car bona ting conditions. The test results show that the optimal time of waterproof is 14 days after the concrete construc. tion but reconsideration is necessary for the application to high strength concrete because of the reduction in penetration of waterproof admixture. The results also show that the penetrat ive waterproof admixture has srrong resistance to the acid rain. However the waterproof capability of the admixture is not permanent especially under the natural exposure. Therefore the slab of a bridge should be paved with asphalt concrete. Other noticeable effects are the increase of heat and abrasion resistances from the use of the waterproof agents.

• Journal of the Korea Institute of Building Construction
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• v.18 no.2
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• pp.109-115
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• 2018

Since the current method of SCW cement milk pouring method uses one to one ratio of cement milk with OPC, there are some problems such as drying shrinkage, increased cost, difficulty of controlling mix proportions for various conditions of applied soil, and precipitation of $Cr^{6+}$ due to the excessively used cement. Specifically, in aspect of sustainability issues of cement manufacturing, the consumption of cement should be reduced. Hence, in this research, as a replacement of cement for SCW method, blast furnace slag with sulfate or alkali as a stimulant, and expansive admixture were used. By using blast furnace slag as a hardening composite of SCW, there are many advantages such as free controllable mix proportions, rapid setting time with less mud occurrence, less cost with less energy for mixing, constant strength development, and less precipitation of $Cr^{6+}$. Regarding the alternative composites for SCW, in this research, durability and chloride resistance were evaluated.