• 대한화장품학회지
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• 제34권2호
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• pp.93-99
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• 2008

지금까지 (-)-epigallocatechin-3-gallate(EGCG)는 인간의 피부에 유용한 녹차 카테킨 중에서 가장 강력한 항산화 성분으로 알려져 왔다. 본 연구팀은 용매, 온도, 압력 등 다양한 조건을 변화시키며, 멸균과정(autoclaving) 중에 발생하는 이성질체화(epimerization) 과정을 연구하여, gallocatechin-3-gallate(GCG) 함량이 크게 증가된 열전환-EGCG-복합체(heat-epimerzied-EGCG-mixture, HE-EGCG-mix)를 순수한 EGCG로부터 조제 하였다. 이러한 열전환-EGCG-복합체는 무모쥐 SKH-1을 이용한 실험에서, 손상된 피부 장벽의 회복 시에 인보루크린 7(involucrin 7) 단백질의 발현량을 EGCG 처리 시보다 증가시킴을 확인하였다. 또한, in vitro 실험을 통하여 GCG는 $PPAR-{\alpha}$에 대한 전이활성(transactivation) 효과가 EGCG보다 뛰어남을 확인하였다. 이러한 결과는 열전환-EGCG-복합체에 함유된 고함량의 GCG 성분에 의해서, 피부 장벽 손상 회복 시 PPAR에 의해 매개된 각질형성세포(keratinocyte)의 분화가 더욱 촉진될 수 있음을 암시한다. 따라서, EGCG의 C-2 에피머(epimer)인 GCG는 녹차 카테킨을 이용한 피부 장벽 개선 용도의 화장품과 건강식품 개발 시 주요 소재로 활용될 수 있다.

• 한국세라믹학회지
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• 제48권6호
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• pp.589-594
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• 2011

Raw mix of molten clinker was fabricated using blast furnace slag as starting material. Raw mix was melted at 1620$^{\circ}C$ for molten clinker fabrication. It was found that molten clinker contained alite and belite equivalent to OPC clinker mineral by optical microscope and SEM. The size of alite was 10~50 ${\mu}m$ and that of belite was 20~80 ${\mu}m$. This result thought to be attributed low $Al_2O_3$ content and cooling condition. Interstitial phase increased with blast furnace slag content and gehlenite was formed by the condition of LSF and SM. So raw mix with 27~41% blast furnace slag could be converted into cement clinker by appropriate choice of melting andcooling methods in this study.

• Computers and Concrete
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• 제25권5호
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• pp.401-409
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• 2020

Artificial neural networks are used as a useful tool in distinct fields of civil engineering these days. In order to control long-term quality of Self-Compacting Semi-Lightweight Concrete (SCSLC), the 90 days compressive strength is considered as a key issue in this paper. In fact, combined artificial neural networks are used to predict the compressive strength of SCSLC at 28 and 90 days. These networks are able to re-establish non-linear and complex relationships straightforwardly. In this study, two types of neural networks, including Radial Basis and Multilayer Perceptron, were used. Four groups of concrete mix designs also were made with two water to cement ratios (W/C) of 0.35 and 0.4, as well as 10% of cement weight was replaced with silica fume in half of the mixes, and different amounts of superplasticizer were used. With the help of rheology test and compressive strength results at 7 and 14 days as inputs, the neural networks were used to estimate the 28 and 90 days compressive strengths of above-mentioned mixes. It was necessary to add the 14 days compressive strength in the input layer to gain acceptable results for 90 days compressive strength. Then proper neural networks were prepared for each mix, following which four existing networks were combined, and the combinatorial neural network model properly predicted the compressive strength of different mix designs.

• 한국농공학회지
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• 제43권6호
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• pp.127-134
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• 2001

In order to expand agricultural lands in the western and southern coasts of Korean Peninsula, coarse soils excavated from hillsides have been used as fill materials for reclamation. In order to tackle with the problems and to confirm availability, research on soil improvement involve mixing cement to the fine wet soils. Required undrained shear strength$(C_u)$ for fill material was analysed to be 0.34~1.2 $kgf/cm^2$. It has been known that when cement is added to high water content marine clay its unconfined compression strength increased to 2 $kgf/cm^2$. Consolidation results show that pre-consolidation pressure increased to 1.8 $kgf/cm^2$and 3.4 $kgf/cm^2$ with the addition of 3% and 5% of cement respectively. This result shows that low-height embankments could be constructed without significant compression. Since the effectiveness of improvement may be different site by site, the mix design for each site is necessary in order to optimize it. The process is first to determine aimed shear strength and then optimum mix ratio of cement after carrying out a series of tests.

• 한국농공학회논문집
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• 제58권2호
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• pp.83-90
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• 2016

This study was performed to evaluate the effective analysis of flexural performance for polypropylene fiber (PF) reinforced EVA concrete that can be used in marine bridge, tunnel and agricultural structures under flexural load. The control design was applied in ready mixed concrete using 10 % fly ash of total binder weight used in batch plant. On the basis of the control mix design, there was designed mix types that contained PF ranged from 0 % to 0.5 % by volume ratio into two mix types of using 0 % and 5.0 % EVA contents of total binder weight. Before evaluating the flexural performance, we tested compressive strength and flexural strength to evaluate whether polypropylene fiber reinforced concrete could be used or not in site. The method of flexural performance evaluation was applied by ASTM C 1609. These results showed the maximum compressive strength and flexural strength was measured at each E5P1 and E5P2. Concrete reinforced with PF exhibited deflection-softening behavior. In the concrete reinforced with 0.4 % PF contents and containing 5.0 % EVA, the flexural performance was the best.

• Advances in nano research
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• 제3권2호
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• pp.55-66
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• 2015

Crystalline $Ce^{3+}$ co-doped $LaPO_4$:RE ($RE=Dy^{3+}$, $Tb^{3+}$, $Eu^{3+}$, $Sm^{3+}$) and mix doped rare earth ions of $Dy^{3+}$, $Tb^{3+}$ and $Eu^{3+}$ were prepared by the polyol method at $150^{\circ}C$. Strongly enhance luminescence intensity is obtained with the co-doping of $Ce^{3+}$ with $LaPO_4$:$Dy^{3+}$ and $LaPO_4$:$Tb^{3+}$ due to charge transfer (CT) occurring from $Ce^{3+}$ to $Dy^{3+}$ and $Ce^{3+}$ to $Tb^{3+}$, where as there is no significant changes in luminescence intensity of $Ce^{3+}$ co-doped $Eu^{3+}$ and $Sm^{3+}$ doped $LaPO_4$ samples. The luminescence color can be tuned from green to white by varying the excitation wavelength for the mix ions $Ce^{3+}$, $Dy^{3+}$, $Tb^{3+}$ and $Eu^{3+}$ doped with $LaPO_4$.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.94-99
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• 1992

In this study , some factors such as mix proportion, type and dosage of high range water reducing admixture(HRWR) and natural pozzolanas influencing on the slump loss of high strength concrete(H.S.C) using HRWR were investigated for reducing the slump loss. The acquired results indicated that the slump loss of H.S.C was affected according to cement content, sand percentage and type and dosage of HRWR and fly ash was superior to ground granulated blast furance slag in reducing the slump loss of H.S.C.

• 원예과학기술지
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• 제19권4호
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• pp.505-510
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• 2001

춘파 당근 종자의 발아능 향상을 위한 적정 SMP조건 구명과 처리기간 중 종자의 생리적 변화를 관찰하기 위하여 이나리, 만산5촌, 무쌍5촌, 홍심5촌 등 4개 품종을 공시하여 실험을 실시하였다. SMP 처리에서 물질(Micro-Cel E)에 대한 물의 첨가배율이 높아지고 처리기간이 길어질수록 발아율이 높고, $T_{50}$이 단축되었지만 처리과정 중 일부 처리에서는 유근이 돌출되었다. 품종에 따른 SMP조건이 다소 달랐다. SMP의 적정 종자 : 물질 : 수분의 비율은 5 : 3: 10.5이고 적정 처리기간은 만산5촌이 3일, 그 외 3품종은 5일이었다. SMP적정처리 온도는 $20-25^{\circ}C$인 것으로 나타났다. SMP 기간 중 종자의 변화 중에서 수분흡수율은 처리 후 1시간까지 급속하게 증가하고 그 후 6기간까지 약 38%로 증가하다가, 24시간째에는 품종에 따라 43%-49%를 보였다. 그 이후부터는 처리종료시간까지 일정하게 유지되었다. 종자의 전기전도도는 6시간까지 감소하여 $100{\mu}S{\cdot}cm^{-1}$ 내외에서 거의 변화를 보이지 않았고, pH는 초기에 약간 높아지다가 처리기간이 경과할수록 원래의 pH로 되돌아오는 경향을 보였다.

• 한국유기농업학회지
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• 제22권1호
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• pp.183-195
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• 2014

본 연구는 가축의 축사에 깔짚으로 이용되는 톱밥을 수준별(0(CSD0구), 10(CSD10구), 20(CSD20구), 30(CSD30구) 및 40%(CSD40구))로 우분과 혼합한 다음 부숙기간 중의 이화학적 성상 변화가 지렁이 생존에 미치는 영향을 조사함으로써 vermicomposting을 이용한 가축분의 친환경적 처리에 기초자료로 이용하고자 실시되었다. 그 결과를 요약하면 다음과 같다. 부숙이 경과함에 따라 3주부터 모든 구에서 지렁이의 생존이 가능하였다. 처리구별 탄질비는 톱밥 혼합구가 CSD0구 보다 유의하게 높았다(p<0.05). 지렁이가 생존하기 시작한 3주차의 탄질비는 23.26~61.05로 나타났다. 부숙이 경과함에 따라 pH와 전기전도도는 CSD0구에서 가장 높았고, 톱밥의 혼입 비율이 높을수록 pH와 전기전도도는 낮은 경향이었다. 지렁이가 생존하기 시작한 pH와 전기전도도는 각각 7.4~7.7과 0.28~1.17mS/cm으로 나타났다. 이상의 결과를 종합해 보면 우분에 다양한 수준의 톱밥을 혼합하여 부숙시켰을 경우 이화학적 성상 변화는 모두 지렁이 생존이 가능한 범위로 나타났으나, 우분의 효율적인 지렁이 퇴비화를 위해서는 톱밥 혼입 비율에 따른 지렁이의 생육과 증식 조사를 위한 시험이 필요하다고 사료되어 진다.

• Journal of Preventive Medicine and Public Health
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• 제21권2호
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• pp.390-403
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• 1988

The objectives of the study were to provide the basic informations needed in the development of balanced medical services throughout the nation. As the national health care system was expanding rapidly along with the economic growth, quantitative re-evaluation of the system is of great need. For that reason, characteristics of the admitted patients were analyzed for the case-mix and patients' flow within and through regions. Materials were 421,530 cases of inpatients, who were reported through Korea Medical Insurance Corporation(KMIC) for insurance claim, during the period of March 1, 1985 through February 28, 1987. Korean Diagnosis Related Groups(K-DRGs) classification system was adopted for the study of case-mix and 189 cities and counties were classified into 5 district groups by factor analysis results of K-DRGS. The major findings of this study were as follows ; 1) Factor analysis of case-mix, employing K-DRG system, revealed 5 distinct funtional district groups. Group A(18 districts) was prominent for tertiary medical care. In group B(36 districts), rather simple procedures were prevalent. Group C(26 districts) was distinctive for the medical care of well organized internal medicine practices with qualified clinical laboratories. Group D(17 districts) was characterized by relatively high balanced medical care. Group E (92 districts) was with very low level of medical care. 2) Analysis of the case-flow through the districts showed 3 types of flow patterns : inflow, outflow, and balanced types. Inflow type of case-flow was found in Group A, C and D while Group B and E showed outflow type. Inflow was most prominent in Group A and Group E was of typical outflow type. Group B was consistently the outflow type except for Major Diagnostic Category XX regardless of the disease treaters, but Group C and D were inflow or outflow types according to the disease tracers.