• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.42.1-42.1
• /
• 2010

Poly-carprolactone (PCL)은 생분해성 고분자로 장기간의 임상실험 결과 생체에 독성이 없으며 생체친화성이 우수한 소재로 확인되어 PLGA, PLLA 등과 더불어 조직공학 분야에서 널리 사용되고 있는 생체재료이다. 그러나 PCL은 5개의 비극성 methylene group과 1개의 극성 ester group이 반복되는 지방족의 polyester로 구조상 탄소수가 많아 소수성을 띄는 단점을 가지고 있다. 이러한 표면이 소수성인 재료의 경우, 초기 단백질 흡착능이 떨어져 세포의 부착이 느린 속도로 일어나므로 세포 분화 및 조직 재생이 더디게 일어난다. 본 연구에서는 소수성의 PCL 표면의 단백질 흡착능을 증가시키기 위해 기능성 amine group을 부착하였으며, 또한 골재생을 촉진시킬 수 있는 세포외 기질인 collagen과 osteopontin을 부착함으로써 고기능성 PCL membrane을 제조하였다. 제조된 PCL membrane은 골재생용 조직공학에의 응용을 위해 지방유래 줄기세포를 이용하여 부착능 및 골세포로의 분화능을 확인하였다. 표면 성질의 변화에 의한 세포의 부착능의 변화를 confocal microscopy을 이용하여 부착에 관여하는 단백질의 발현을 확인하였으며, collagen과 osteopontin에 의한 골세포로의 분화능을 확인하기 위해 real time PCR을 통해 골세포의 분화 표지 유전자의 발현을 비교 분석하였다.

• Korean Journal of Food Science and Technology
• /
• v.47 no.1
• /
• pp.44-50
• /
• 2015

The purpose of this study was to characterize the lactic acid bacteria found in makgeolli in terms of bacterial identity and gastric compatibility. Lactic acid bacteria were isolated from commercial raw makgeolli and separated into six strains that are resistant to gastric acidity and bile acid. These strains were identified by analysis of their 16S rDNA, as Lactobacillus plantarum BSM-2 and EHJ-1, Lactobacillus casei GSM-3 and EHJ-2, Lactobacillus brevis BSM-3 and Pediococcus pentosaceus TJH-1. All strains exhibited adhesion to intestines, showing that they were probiotic. We also found that L. plantarum BSM-2 had excellent resistance to bile acid as well as antioxidant activity. Taken together with its antibacterial properties and ability to lower cholesterol, our data suggest that L. plantarum BSM-2 was the most beneficial probiotic among the six strains.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.29 no.4
• /
• pp.618-624
• /
• 2002

Effect of the roasted barley tea in commercial markets on the adherence to the saliva-coated hydroxyapatite(HA) beads and the cell surface hydrophobicity of Streptococcus mutans and Streptococcus sobrinus as cariogenic microorganism was examined in vitro. Adherence activity and hydrophobicity in bacteria tested in all the barley tea samples decreased and the values were different according to the type of tea and the type of treatment. The inhibition of bacterial adsorption to HA beads suggest that barley tea active molecules as catechins and melanoidins may adsorb to a host surface, preventing the tooth receptor from interacting with any bacterial adhesions. The obtained results showed that the barley tea may inhibit bacterial adherence, the first step of the pathogenesis of dental caries in which these microorganism are involved.

• Proceedings of the KAIS Fall Conference
• /
• 2001.05a
• /
• pp.84-86
• /
• 2001

본 논문에서는 고성능 활성탄의 악취 및 유해가스 흡착효율과 멜트브로운(M/B)부직포의 여과성능에 의한 복합적인 고기능 방진특성을 갖는 활성탄 부착 M/B 국산화 여과재를 제조개발하였다. 고성능 활성탄은 고순도의 일반활성탄에 금속염, 유기물 등을 담지시켜 활성화시킨 활성탄이고, M/B여과재의 웹(web)제조조건은 M/B 방사기에서 방사온도 250℃, 방사속도 150m/sec, 고온공기온도 250℃ 그리고 DCD(die to collector distance) 20cm가 적합함을 알 수 있었다. 또한 M/B 여과재에 활성탄 부착은 열롤러시스템에 의한 열적결합방법을 이용하여 균일한 분포의 점접착결합구조를 갖도록 하였고, 개발된 복합기능 여과재가 방진마스크용 여과재로의 이용이 가능하다는 것을 분진포집효율, 투과율, 흡기저항 등 여과재 성능기준실험 결과를 통해 확인하였다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.18 no.6
• /
• pp.21-29
• /
• 2014

This paper deals with the bonding characteristic of grouted joint connections of monopile support structures for offshore wind power facilities. For the integration of pile connection of wind power supporting structure, fiber reinforced high performance cementeous grout was developed and the ultimate compressive strength of it is 125MPa and the direct tensile strength is 7.5 MPa at 7 days. To assess the bond strength of grout filled in pile connection, small scaled direct bond tests under axially loaded was performed and analyzed according the existing guidelines. The fiber volume fraction (0%, 0.5% and 0.9%), aspect ratio of fiber (60 and 80) and the ratio of height to spacing of shear key (0.013 and 0.056) were adopted as the experimental variables. From the test results, the maximum bond strength among the all specimens was 30.8MPa and the bond strength of grouted connection was affected by the ratio of height to spacing of shear key than the fiber volume fraction.

• Korean Journal of Ecology and Environment
• /
• v.42 no.1
• /
• pp.124-133
• /
• 2009

Effects of substrates on the relative immigration activities (RIAs) of epilithic diatoms were examined in Sum River, a tributary of South Han River, Korea. Two hundreds of tile substrates coated with 5% agar were deposited at seven study stations (30 tiles per site) for one month from March 7 to April 7, 2008. Water sampling, physico-chemical factor measurement, and diatom analysis were performed in the field and laboratory. Over the study, major epilithic diatom species were Nitzschia amphibia, Navicula subminuscula, Cymbella minuta in both the natural and artificial substrates. Two dominant species, Nitzschia amphibia and Cymbella minuta often found at seven stations. Among all observed taxa, Nav. subminuscula and Caloneis silicula showed the highest RIA, with the value over 15 throughout the study. Regarding the algal morphology, the biraphe type species showed higher RIA than any other morph, while they comprised over 55% of total biomass, indicating a density effect. Additionally, a significant relationship between RIA and 20-day deposited substrate (p<0.05) showed in two diatom species, Nitzschia fonticola, Gomphonema quadripunctatum, which showed relatively high RIAs. These results indicate that the relative immigration activities of epilithic diatom species can be influenced by algal density in the water and substrate, nutrients, and deposited time at least 20 days.

• 한국HCI학회:학술대회논문집
• /
• 2006.02a
• /
• pp.467-473
• /
• 2006

가상환경 또는 실제환경에서 정보를 제공하는 햅틱 인터페이스의 필요성이 점점 증가 함에 따라 촉감을 제공 하기 위한 다양한 햅틱 장치가 개발되었고 각 장치의 특성과 성능 평가를 위해 기초적인 정신(심리) 물리학적 연구가 수행 되고 있다. 본 논문에서는 여러 가지 햅틱 인터페이스 중 손가락 끝에 부착하는 형태의 새로운 공기 촉감 제시장치(PTI: Pneumatic Tactile Interface)를 제시하고 이 장치의 유용성을 입증하기 위해 localization rate, 시간 분해능, 길이 분해능, 강도의 세기 등의 심리 물리학적 실험(Psychophysical Experiment) 수행 결과를 제시한다. 공기촉감 시스템은 50개의 출력까지 확장 가능한 공기촉감 하드웨어로 구성 되어있고 손가락 끝에 부착하는 형태로 구성 하기 위해 5*5의 배열의 디스플레이를 제작하였다. 16명의 피실험자가 A, B 두 그룹으로 나뉘어 각각 2가지의 심리물리학 실험을 수행하였다. localization rate의 경우 9개의 다른 자극의 위치를 구별하기 위해 3*3 배열로 구성된 밀집된 디스플레이와 확장된 디스플레이로 측정을 수행하여 각각 58.13%, 85.9%의 localization rate를 얻을 수 있었다. 그리고 100번의 반복 실험을 통해 약 2.6mm의 길이 분해능을 얻을 수 있었고 자극 강도 실험의 경우, 실제의 강도가 세짐에 따라 피 실험 자들이 느끼는 강도의 척도도 증가 하며, 강도가 약해 질수록 피 실험 자들이 느끼는 강도 역시 거의 선형적으로 감소함을 알 수 있었다. 그러나 시간 분해능의 경우에는 시스템을 구성하는 밸브의 성능으로 인해 20ms 이하의 시간 분해능 측정은 제한 되었다. 이러한 심리 물리학 실험을 통하여 개발된 공기촉감 제시장치가 다양한 정보를 전달하는데 충분하다는 결론을 내릴 수 있으며, 제안된 시스템을 사용하는 여러 가지 어플리케이션을 제시하였다.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.2
• /
• pp.218-224
• /
• 2008

Coal-, coconut- and wood-based activated carbons and anthracite were tested to evaluate adsorption and biodegradation performances of chloral hydrate. In the early stage of the operation, the adsorption was the main mechanism for the removal of chloral hydrate, however as increasing populations of attached bacteria, the bacteria played a major role in removing chloral hydrate in the activated carbon and anthracite biofilter. It was also investigated that chloral hydrate was readily subjected to biodegrade. The coal- and coconut-based activated carbons were found to be most effective adsorbents in adsorption of chloral hydrate. Highest populations and activity of attached bacteria were shown in the coal-based activated carbon. The populations and activity of attached bacteria decreased in the order: coconut-based activated carbon > wood-based activated carbon > anthracite. The attached bacteria was inhibited in the removal of chloral hydrate at temperatures below 10$^{\circ}C$. It was more active at higher water temperatures(20$^{\circ}C$ <) but less active at lower water temperature(10$^{\circ}C$>). The removal efficiencies of chloral hydrate obtained by using four different adsorbents were directly related to the water temperatures. Water temperature was the most important factor for removal of chloral hydrate in the anthracite biofilter because the removal of chloral hydrate depended mainly on biodegradation. Therefore, the main removal mechanism of chloral hydrate by applying activated carbon was both adsorption and biodegradation by the attached bacteria. The observation suggests that the application of coalbased activated carbon to the water treatment should be the best for the removal of chloral hydrate.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.5
• /
• pp.581-585
• /
• 2005

Five lactic acid bacteria (LAB) including 2 Lactobacillus strains isolated from Kimchi were evaluated to determine the binding ability to Caco-2 cells and $AFB_1$. LAB were divided into three different groups ; viable, heat-treated, and acid-treated cells. In the radioactive-labeling assay for bound cell counting, viable Lactobacillus Plantarum KCTC 3099 showed the higher adhesion to Caco-2 cells with the binding capacity of $39.2\%$, which was $149\%$ higher than Lactobacillus rhamnosus GG as a positive control. Leuconostoc mesenteroids KCTC 3100 showed the similar binding ability to L. rhamnosus GG. After 1 hour incubation at $37^{\circ}C$ with $AFB_1$, viable L. Planterum KTCC 3099 removed the toxin by $49.8\%$, which was similar level to L. rhamnosus GG. Both heat- and acid-treated groups showed high binding effect but acid-treated group was more effective for both Caco-2 cell binding and $AFB_1$ removal than the other. These results indicate that components of bacterial cell wall might be involved in tile binding to intestinal cells and toxins.

• Magazine of the Korea Concrete Institute
• /
• v.10 no.6
• /
• pp.169-178
• /
• 1998

Bond strength of reinforcing bar to high-perfomance concrete using belite cement is explored using beam end test specimens. The key parameters for the bond test are slump of concrete, top bar effect, and strength of concrete in addition to concrete cover. The test results show that the specimens with belite cement concrete show approximately 10% higer bond strength than those with portland cement concrete. The results also show that the bond strength from the high strength concrete is function of the square root of concrete compressive strength. Bond strength of the top bar is less than bond strength of bottom bar, but the ratios of the bond strength of bottom-cast bars to those for top-cast bars are much less than the modification factor for top reinforcement found in the ACI 318-95 code. Comparisons with other reported tests identified that belite cement increased bond strength while silica fume or flyash used in high strength concrete decreased bond strength. The high-strength and high-slump concrete with belite cement performs well in terms of bond strength to reinforcing steel.