• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.471-476
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• 2006

Pseudomonas aeruginosa F722 produces a biosurfactant (BS) during its degradation of carbon and hydrocarbon compounds. The culture conditions for upgrading the biosurfactant productivity were investigated. The concentration of the biosurfactant produced by P. aeruginosa F722 was 0.78 g/L in C-medium; however, this increased to 1.66 g/L in BS medium, which was experimentally adjusted to optimal conditions. $NaNO_{2}$ was found to be most effective for microbial growth, with an $O.D_{600nm}$ of 1.18 for 0.1 % $NaNO_{2}$. Microbial growths, according to the $O.D_{600nm}$ were 2.53, 2.68, 2.89, and 2.87 for glucose, glycerol, $n-C_{10},\;and\;n-C_{22}$, respectively. Clear zone diameters (cm), indicating biosurfactant activity, were 9.0, 8.8, 5.7, and 8.5 for glucose, glycerol, $n-C_{10},\;and\;n-C_{22}$, respectively. Microbial growth was not consistent with the biosurfactant activity. The best biosurfactant activity was found with a C/N ratio of 20. Under optimal culture condition, the average surface tension decreased from 70 to 30 mN/m after 5 days. With aeration of 1.0 vvm, the biosurfactant produced increased to 1.94 g/L (up to 20%) compared to that of 1.66 g/L with no aeration. With aeration, the velocities of glucose degradation during both the log and stationary growth phases increased from 0.25 and $0.18\;h^{-1}$ to 0.33 and $0.29\;h^{-1}$, respectively, and the time for the culture to arrive at the maximum clear zone diameter became shorter, from 80 down to 60 h with no aeration.

• 한국식품조리과학회지
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• 제15권4호
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• pp.410-417
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• 1999

우리나라 야산에서 쉽게 구할 수 있는 구황 식물인 질경이를 메탄올과 여러 용매로 추출하여 식품 부패 미생물에 대한 항균력을 실험하고 그 항균활성 물질을 분석하여 다음과 같은 결과를 얻었다. 질경이의 메탄올 추출물은 2000$\mu\textrm{g}$/ml 농도에서 B. subtilis 및 V. parahaemolyticus의 증식을 100% 억제하였다. 그리고 질경이의 ethylacetate 분획물은 1000$\mu\textrm{g}$/disc 농도에서 5종의 모든 실험 균주에 대하여 8.5~11mm 크기의 clear zone을 형성하여 가장 높은 항균력을 보였다. 질경이의 ethylacetate 분획물을 silica gel column chromatography와 TLC로 분리하여 얻은 fraction을 5가지 실험 균주에 대하여 항균 실험을 한 결과 3rd 분획물 중 4번째 분획물이 250$\mu\textrm{g}$/disc 농도에서 모든 균주에 대하여 10 mm 이상의 clear zone을 나타내었다. 항균력을 보인 질경이의 ethylacetate 3rd fraction No. 4를 HPLC로 단일 분리하여 얻은 peak IV로 부터 $^1$H-NMR 및 GC-MSD로 동정한 결과 hexadecanoic acid로 동정되었다.

• 문화기술의 융합
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• 제8권6호
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• pp.605-614
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• 2022

본 연구에서는 오레가노를 초임계유체추출법과 열수추출법으로 추출하여 항균, 항산화 in vitro 실험을 수행하였다. 항균실험인 Disc diffusion method 결과, 초임계추출물에 대해서만 clear zone이 나타났다. S. aureus에 대한MIC는 초임계추출물에서만 관찰되었으며, 1000 ㎍/mL로 확인되었다. 열수추출물은 C. acnes에 대한 MIC가 125 ㎍/mL로 여드름균에 대한 항균력이 뛰어났다. 나아가 우리는 Biofilm inhibition assay를 통해 오레가노 초임계추출물이 125 ㎍/mL의 저농도에서도 S. aureus의 바이오필름을 70%이상 억제한다는 것을 발견하였다. DPPH radical 소거능, ABTS+ radical 소거능, SOD 유사활성능과 총 폴리페놀 함량 측정에서 열수추출물의 항산화력이 초임계추출물보다 우수하게 측정되었다. 나아가, 앞서 확인된 오레가노 초임계추출물의 S. aureus 바이오필름 억제능을 활용하여 아토피 피부에 적합한 소재를 개발하고자 하였다. 오레가노 초임계추출물의 낮은 용해도를 극복하고 안정성을 증가시키기 위하여 리포좀을 이용하였다.

• 한국식생활문화학회지
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• 제20권6호
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• pp.709-714
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• 2005

동결 건조된 죽력을 물 또는 50% ethanol에 각각 용해시킨 시료(1 mg eq./disc)에 대하여 항세균 활성을 측정한 결과, 물에 용해시킨 죽력은 gram 양성균의 경우 L. monocytogenes이 15 mm의 저해환으로 가장 활성이 강하였고 B. subtilis는 활성이 전혀 나타나지 않았으며 Gram 음성균의 경우는 S. dysenteriae가 저해환이 22 mm로 가장 강한 활성을 보였다. 50% ethanol에 용해시킨 죽력은 gram 양성균의 경우 L. monocytodenes, 가 가장 강한 활성을 보였으나 B. subtilis는 활성이 전혀 없던 물에 용해시킨 경우에 비하여 활성이 크게 나타났다. Gram 음성균의 경우, S. dysenteriae가 23 mm저해 환으로 가장 강한 활성을 보였고 V. parahaemolyticus, V. vulnificus, E. coli O157:H7는 16 mm로 상대적으로 약한 활성을 보였다. 젖산균 2종의 경우는 물 또는 50% ethanol에 용해시킨 경우 모두 전혀 활성을 나타내지 않았다. 최소저해농도는 L. monocytogenes는 50% ethanol에 녹인 경우 MIC가 0.6 mg/disc로 가장 낮았고 물에 용해시킨 죽력의 경우 S. epidermides, S. dysenteriae, L. monocytogenes, Sal. typhimurium, V. parahaemolyticus가 각각 0.8 mg/disc의 MIC값을 나타내 50% ethanol에 용해시킨 경우에 비하여 MIC값이 높은 경향을 보였으며 다른 세균들은 1.0 mg/disc의 거의 유사한 MIC값을 보였다. Model food system에서의 저해활성은 물에 용해시킨 죽력 보다 50%, ethanol에 용해시킨 죽력이 대조구에 비하여 생육을 강하게 저해하였고 MIC가 낮은 이들 4가지 공시균주들이 모두 model food system상에서 상당히 강한 저해활성을 나타내 50% ethanol에 용해시킨 죽력은 적절한 농도에서 부패세균들의 생육 억제제로 사용 가능할 것으로 사료되었다.

• 문화기술의 융합
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• 제5권3호
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• pp.271-282
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• 2019

본 연구의 목적은 아카시아 잎의 생리활성을 평가하고 고분자 미셀과 세포투과 펩티드를 이용한 피부흡수 증진에 관한 것이다. 아카시아 잎을 열수 및 에탄올 추출한 후에, 항노화, 미백, 항균 등 다양한 생리활성을 측정하였다. 총 polyphenol 함량은 열수 추출에서 56.88 mg/g, 에탄올 추출에서 47.42 mg/g이고, DPPH radical 소거능은 농도 $1,000{\mu}g/mL$에서, 에탄올 추출물의 경우 44.24% 저해율을 나타냈고 이는 열수 추출물의 값(41.50%)보다 더 좋은 효능을 나타냈다. Elastase 저해능 실험결과에서 농도 의존성을 보였으며, 아카시아 잎 에탄올 추출물 $500{\mu}g/mL$에서 가장 높은 54.09% 저해능, 열수 추출물은 36.95% 저해능을 보였다. SOD 유사 활성능 결과에서 농도 의존적인 결과를 보였고, 모든 농도에서 아카시아 잎 에탄올 추출물이 열수 추출물의 값보다 높았다. $500{\mu}g/mL$에서 76.41%, 같은 농도에서 아카시아 잎 에탄올 추출에서 86.31%로 더욱 높은 활성을 나타냈다. Tyrosinase 저해능 실험에서는 아카시아 잎 에탄올 추출물 농도 20 mg/mL에서 56.47% 저해율, 아카시아 잎 열수 추출물은 23.05% 저해율이 나타났다. 항균실험 결과에서는 아카시아 열수 추출물은 항균효과를 나타내지 못했지만, 아카시아 에탄올 추출물은 P ropionbacterium acnes 균주에서 11.00 mm의 최대 clear zone을, Bacillus subtilis 균주에선 10.50 mm로 최대 clear zone을 제시하였다. 난용성 문제와 피부 흡수율을 증진시키기 위하여, 아카시아 에탄올 추출물과 1.0% 세포투과 펩티드(6개 알르기닌, R6)을 함유한 108.23, 126.47 nm로 약 1/10배 미세한 나노입자 크기를 갖는 PCL-PEG 고분자 미셀이 성공적으로 제조되었고, 우수한 경피흡수 증진 효과를 나타낼 수 있었다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.639-643
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• 2002

The main purpose of this study was to investigate the formation mechanisms of imperfections such as irregular humps, outer cavity and inner cavity in the laser fusion zone of diamond saw blade. Laser beam welding was conducted to join two parts of blade; mild steel shank and Fe-Co-Ni sintered tip. The variables were beam power and travel speed. The microstructure and elements distributions of specimens were analyzed with SEM, AES, EPMA and so on. It was found that these imperfections were responded to heat input. Irregular humps were reduced in 10.4∼17.6kJ/m heat input range. However there were no clear evidences, which could explain the relations between humps formation and heat input. The number of outer cavity and inner cavity decreased as heat input was increased. Considering both possible defects formations mechanisms, it could be thought that outer cavity was caused by insufficient refill of keyhole, which was from rapid solidification of molten metal and fast molten metal flow to the rear keyhole wall at low heat input. More inner cavities were found near the interface of the fusion zone and sintered segment and in the bottom of the fusion zone. Inner cavity was mainly formed in the upper fusion zone at high heat input whereas was in the bottom at low heat input. Inner cavity was from trapping of coarsened preexist pores in the sintered tip and metal vapor due to rapid solidification of molten metal before the bubbles escaped.

• 한국ITS학회 논문지
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• 제2권1호
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• pp.53-62
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• 2003

본 연구는 건설교통부 ITS R&D 사업 「신호교차로 내 딜레마구간 차내경고시스템 개발」 과제로써 첨단차량 및 도로 분야(AVHS)의 운전자지원 및 충돌방지시스템 분야로서 신호교차로 내에서 단독 혹은 차량군으로 진입하는 차량들에게 신호변경 시 운전자가 정지 혹은 진입의 의사결정을 안전하게 내릴 수 있도록 신호제어기의 변경정보를 단거리전용무선통신(DSRC)를 통해 실시간으로 사전에 경고를 주는 차내경고시스템을 개발하였다. 본 시스템의 연구개발은 ITS 연구개발을 통한 시스템 통합 및 구축을 실현함으로써 ITS에 대한 대국민 의식전환으로 국내 ITS 산업발전에 크게 기여할 것으로 기대된다.

• 자원환경지질
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• 제16권1호
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• pp.11-18
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• 1983

Gyeongsang Basin in the southeastern part of the Korean peninsular is characterized by many fault systems. To decipher the geotectonical evolution of the Korean peninsular and marginal basins in her adjacent areas it is prerequisite to understand the spatial distribution pattern and mutual relationships of these fault systems. Because of difficulties in finding any criterion to recognize the faults in field, their extension and mutual relationships in ages are not very clear yet. As an attempt to find geophysical criteria to recognize the fault, geoelectrical resistivity survey was carried out in this study. With the Wenner configuration four resistivity soundings and twenty seven resistivity profilings were done. The electrode distance used was up to 50m. From the results of the resistivity soundings and boring data of earlier groundwater investigations the depth of alluvial and weathered zone was established to be at most 20m in the study area. In the resistivity profiling low resistivity anomaly zones are detected on every traverse, which are interpreted as caused by fractures, fault clays and mylonites in the fault zone. The width of the fault zone amounts to 0.3-1km. By correlating and connecting the negative anomaly zones from traverse to traverse one can determine the trend of th of the faultzone and therefore that of fault itself. The recognized fault trend in this way was $N15^{\circ}-20^{\circ}E$ and this coincides with the direction of the inferred fault line from earlier geological surface mapping. With the help of this characteristical negative anomaly the existance of another $N80^{\circ}W$ trending fault was estabished. This study has shown that geoelectrical resistivity survey can be applied successfully to the problem of tracing fault line insofar as a fault zone has been developed along fault line.

• 자원환경지질
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• 제14권2호
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• pp.55-76
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• 1981

Southwestern contact zone of the Boeun granodiorite occurs near the thrust fault between the Ogcheon Group and Majeonri Limestone Formation. Ogcheon Group, metasediments composed of the Munjuri Formation, Changri Formation, and unconformably overlying Hwanggangri Formation, belongs to greenschist facies of regional metamorphism accompanied with deformation of two fold axes, $N10^{\circ}E$ and $N45-65^{\circ}E$ directions. Basic metamorphic rocks occurring in the Changri and Limestone Formations are the meta-basalts and meta-diabases of tholeiitic basalt series. The meta-basalts intruded in the Changri Formation as sills, whereas the meta-diabases in the Changri and Limestone Formations as stocks in appearance. They are considered to have emplaced before the formation of two fold axes and related with the thrust fault, based on the geologic setting of the area. The metamorphic facies are identified to be greenschist facies to epidote-amphibolite facies for the meta-basalt, and epidote-amphibolite facies for the meta-diabases. It is interpreted that such a variety of facies was related from the combination of earlier deuteric alteration and later regional metamorphism. The metasediments in southwestern contact zont of the Boeun granodiorite which is a product of later syntectonic intrusion of middle Jurassic in age, show pyroxene-hornfels facies near the contact and amphibole-horenfels facies away from the contact to the mineral zoning in the contact metamorphic aureole of the Limestone Formation, based on the paragenetic analysis of mineral assemblages. The Limestone in the area appears to be considerably $SiO_2-CaO-MgO-CO_2-H_2O$ can be adopted to evaluate equilibrium conditions of the mineral assemblages in each mineral zone. It is revealed that a temperature gradient was existed accross the contact aureole ranging from the higher igneous side to lower sedimentary side, whereas no clear trend of $XCO_2$ variation appears but high mole fraction. The tremolite diopside-quartz-calcite assemblages occurs in common through the most mineral zones of contact aureole that is in good agreement with the equivalent reaction curve which extends over a wide range of $T-XCO_2$ conditions.

• 농촌지도와개발
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• 제17권4호
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• pp.799-825
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• 2010

The purpose of the present study is to provide policy implications for successful development of the metropolitan economic zone in Korea followed by in-depth case studies on the US Metropolitan Economic Region. This study looked into diverse experiences of the US mega regions investigating their key strategies, requirements and standards, etc. Urban areas in the US are designated based on CBSA, a standard for statistical area since 1950. The US has a clear standard to define rural and suburban area and is trying to reflect urban structural changes including suburbanization. The US annexation system is relatively simple to operate. Furthermore, the system helps the growth of rural areas by gradually incorporating rural areas into urban areas. We found that action plans of the US mega regions facilitate strategic growth and development for balanced territorial development, incorporating multi-dimensional and comprehensive approaches. We also found that the US mega regions are designated with regard to the local natures. Couple of policy implications were extracted from the US experiences. First, since the construction of mega regions in Korea concerns less on the inter-regional connections with other regions, we need to incorporate diverse standards to divide the regions with respect to the spatial and local characteristics. Second, local governments should collaborate with each other for successful economic development of the metropolitan economic zones. Administrative districts renovation can be a immediate and effective solution to facilitate the collaboration. We recommended to consider consolidating administrative areas to construct successful metropolitan economic zones.