• 한국약용작물학회지
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• 제19권4호
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• pp.251-256
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• 2011

The leaves of Hippophae rhamnoides were extracted with methanol and then further fractioned with hexane, ethyl acetate, butanol and water in order to investigate biological activity. Two flavonol glycosides were isolated and identified from ethyl acetate soluble fraction, which showed the strongest antioxidant activity ($RC_{50}$ = 4.33 ${\mu}g/ml$). Isolated two compounds have shown strong free radical scavenging activity. Especially, quercetin 3-O-glucoside ($RC_{50}$ = 2.60 ${\mu}g/ml$) was more active than ${\alpha}$-tocopherol ($RC_{50}$ = 4.67 ${\mu}g/ml$). Total phenol and flavonoid contents were the highest to 4.17 and 1.14 mg/ml in the ethyl acetate soluble fraction. In addition, ethyl acetate soluble fraction was shown to the strongest ${\alpha}$-glucosidase inhibitory activity ($IC_{50}$ = 137.88 ${\mu}g/ml$) among the fractions. The results suggest that leaves of H. rhamnoides could be a potential source of natural antioxidant.

• 콘크리트학회지
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• 제8권5호
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• pp.171-178
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• 1996

본 연구는 소도로 포장용 재료로서 재생콘크리트의 역학적 특성과 성능을 규명하였다. 재생콘크리트는 굵은 골재의 반을 재생골재로 대치하여 제조되었고 이와 함께 천연 잔골재와 유동화제 그리고 플라이애쉬(각각 시멘트 중량의 0.8% 및 5%)가 사용되었다. 실험을 통하여 재령28일 재생콘크리트의 휨강도, 압축강도, 탄성계수 및 파괴인성은 약 $45kg/cm^2$, $250kg/cm^2$, $230,000kg/cm^2$ 및 $0.863 MPa{\cdot}m^{1/2}$으로 나타났고 또한 6개월 지난 후 이 압축강도 및 파괴인성이 크게 향상되었다. 결론적으로 재생콘크리트는 역학적으로 도시나 농촌지역 소도로의 콘크리트 포장 재료로 충분히 적용 가능한 특성을 가진 것으로 판단되었다.

• Preventive Nutrition and Food Science
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• 제10권2호
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• pp.111-117
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• 2005

Radical scavenging activity of water and methanol extracts of mulberry juice and cake prepared from mulberry fruit (Morus spp.) was evaluated using three in vitro assay systems. Mulberry fruits were homogenized with $0.5\%$ trifluoroacetic acid (TFA) in distilled water, filtered with cheeze-cloth and centrifuged to yield mulberry juice and cake. Mulberry juice was evaporated and solubilized in $0.5\%$ TFA in distilled water or $0.5\%$ TFA in $80\%$ aqueous methanol, followed by filtration and evaporation to obtain water (WMJ) and methanol (MMJ) extracts of mulberry juice. Mulberrry cake also was extracted with the above same solvents, and thereby finally obtaining water (WMC) and methanol (MMC) extracts of mulberry cake. Among four extracts, the MMC showed the most potent radical scavenging activity against DPPH radical $(IC_{50}=167.45\;{\mu}g/mL)$, and superoxide $(IC_{50}=36.18\;{\mu}g/mL)$ and hydroxyl radicals $(IC_{50}=467.08\;{\mu}g/mL)$. The WMC also exhibited stronger radical scavenging activity than those of two other mulberry juice extract, WMJ and MMJ. Meanwhile, the MMJ exerted stronger three radical scavenging activity than the WMJ. Total phenolic content of the water and MeOH extracts from mulberry cake was higher than that of the water and MeOH extracts from mulberry juice. Thus, these results suggest that the extracts of mulberry cake with high dietary phenolics may be useful potential source of natural antioxidant as radical scavenger.

• Preventive Nutrition and Food Science
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• 제18권3호
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• pp.188-195
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• 2013

Antioxidants are an important group of medicinal preventive compounds as well as being food additives inhibiting detrimental changes of easily oxidizable nutrients. The present investigation has been carried out to evaluate the antioxidant properties of different solvent extracts of Agriophyllum pungens seeds by various in vitro systems. The antioxidative activities of these samples were determined using four methods: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'- azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, ferric-reducing antioxidant potential (FRAP), and hydroxyl (OH) radical scavenging activities. Additionally, total flavonoids and phenolic contents (TPC) were also determined. Yield of extracts varied widely among solvents and was the highest for water extract (5.642% based on dry weight basis), while ethyl acetate extract exhibited the highest total phenolic content (0.149 mg/mL), total flavonoid content (0.111 mg/mL), and antioxidant activities (P<0.05). The ABTS radical scavenging activity of A. pungens seeds occurred in the following order: ascorbic acid (92.9157%)>BHA (90.1503%)> ${\alpha}$-tocopherol (87.7527%)>APEA (83.9887%) >APWR (75.5633%); the antioxidant activity of the extracts might be attributed to the presence of these phenolics. This suggests that A. pungens seed extract is a potential source of natural antioxidants, which could be added to dietary supplements to help prevent oxidative stress.

• 한국문헌정보학회지
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• 제35권3호
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• pp.173-189
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• 2001

This paper presents a framework for observable behavior that can be used as a basis for user modeling, and it reports the results of a pair of user studies that examine the joint utility of two specific behaviors. User models can be constructed by hand, or they can be teamed automatically based on feedback provided by the user about the relevance of documents that they have examined. By observing user behavior, it is possible to obtain implicit feedback without requiring explicit relevance judgments. Four broad categories of potentially observable behavior are identified : examine, retain, reference, and annotate, and examples of specific behaviors within a category are further subdivided based on the natural scope of information objects being manipulated . segment object, or class. Previous studies using Internet discussion groups (USENET news) have shown reading time to be a useful source of implicit feedback for predicting a user's preferences. The experiments reported in this paper extend that work to academic and professional journal articles and abstracts, and explore the relationship between printing behavior and reading time. Two user studies were conducted in which undergraduate students examined articles or abstracts from the telecommunications or pharmaceutical literature. The results showed that reading time can be used to predict the user's assessment of relevance, that the mean reading time for journal articles and technical abstracts is longer than has been reported for USENET news documents, and that printing events provide additional useful evidence about relevance beyond that which can be inferred from reading time. The paper concludes with a brief discussion of the implications of the reported results.

• Steel and Composite Structures
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• 제22권6호
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• pp.1359-1389
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• 2016

Buckling and free vibration behavior of a laminated cylindrical panel exposed to non-uniform thermal load is addressed in the present study. The approach comprises of three portions, in the first portion, heat transfer analysis is carried out to compute the non-uniform temperature fields, whereas second portion consists of static analysis wherein stress fields due to thermal load is obtained, and the last portion consists of buckling and prestressed modal analyzes to capture the critical buckling temperature as well as first five natural frequencies and associated mode shapes. Finite element is used to perform the numerical investigation. The detailed parametric study is carried out to analyze the effect of nature of temperature variation across the panel, laminate sequence and structural boundary constraints on the buckling and free vibration behavior. The relation between the buckling temperature of the panel under uniform temperature field and non-uniform temperature field is established using magnification factor. Among four cases considered in this study for position of heat sources, highest magnification factor is observed at the forefront curved edge of the panel where heat source is placed. It is also observed that thermal buckling strength and buckling mode shapes are highly sensitive to nature of temperature field and the effect is significant for the above-mentioned temperature field. Furthermore, it is also observed that the panel with antisymmetric laminate has better buckling strength. Free vibration frequencies and the associated mode shapes are significantly influenced by the non-uniform temperature variations.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.172-175
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• 2002

The technique of induced discharge by a pulsed CO2 laser is being applied to control electrical discharge path, material processing, triggered lightning for protecting the power equipments. In this paper, we have investigated about the characteristics of the induced discharge at atmospheric conditions by using a plasma channel, which is produced when a pulsed CO2 laser radiation is focused by a focusing mirror as a trigger source. A plasma channel produced by laser radiation has an effect on decreasing the threshold voltage and inducing the discharge in both needle electrodes. We have confirmed a delay time between a produced plasma channel and an electrical discharge after laser radiation. We provided the decreased voltage lower than the natural discharge voltage between electrode type of needles and was induced the discharge by forming a plasma channel between them. In this research we could understand the time delay of induced discharge by laser radiation, and the characteristics of the discharge cause by the decrease in the threshold voltage, and the polarity effect by changes of plasma channel positions between two electrodes.

• 대한지역사회영양학회지
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• 제13권3호
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• pp.405-417
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• 2008

The purpose of the study was to investigate the sanitation management status and implementation barriers of the HACCP system. A survey was conducted based on 760 schools through e-mail after having gone through phone interviews to dieticians in Seoul, Gyeonggi and Incheon areas from December 2006 to March 2007. The following statistics were drawn out from the 459 surveys out of the 760, thus giving a response rate of 60.4% (N = 459). The statistical data analysis was completed using the SPSS program. 92.6% of the respondents operated sanitary education once a month and 67.1 % used internet as their sanitary educational source. 50.5% of the pre-preparation rooms were not divided and 78.0% of kitchen floors were always kept wet. Only 15.7% of the respondents used heat and cold insulators and 73.2% of drinking water was natural or purified water. 60.3% of food trays were electronically sterilized and 70.2% of spoons and chopsticks were sterilized by boiling water. The main cause of food-borne diseases was the lack of facilities and equipment (33.1%). Also, the deficiency of facilities and equipment (4.07 points) acted as an implementation barrier of the HACCP system. Compared to Gyeonggi or Incheon area results, Seoul's facilities and equipment (p < 0.001) and implementing barriers of the HACCP system (p < 0.001) results came out relatively high. After the analysis of the implementation barriers of the HACCP system, 91.7% of school principals said it was difficult to apply the HACCP system due to lack of financial support. In consideration to the school foodservice support, solutions for the facilities of school foodservice and a systematic sanitary education of the HACCP system must be made for the employees and everyone else who are related.

• 디자인학연구
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• 제17권3호
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• pp.91-100
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• 2004

자연은 끊임없이 신비한 산물들을 대량생산해내는 만물의 공장이며, 그 산물들은 끊임없이 변화하고 있다. 또한 자연은 인간이 살아가는 환경을 둘러싼 미적 아이디어를 끊임없이 제공한다. 그러므로 인간은 자연을 대상으로 시각적 관찰을 통해 표현하고자 하는 자연스런 충동에 따른 조형을 추구하게 된다. 자연에 대해 인간이 얻을 수 있는 미적 체험은 그 대상에 대하여 시각적으로 연구할 때, 연상에 따른 형상들을 의식적으로 떠올릴 수 있게 해주는 미학적 변형의 원천인 것이다. 수없이 변화된 자연물과 마찬가지로 의식적으로 경험되는 인 공의 산업 생산물은 자연물과 구조적, 형태적 질을 공유하며 조형적 균형을 위한 의미를 갖게 된다. 자연을 관찰하여 질서나 원리를 통해 디자인에 적용시키고자한 시도는 바우하우스 이후 디자인의 한 방법으로서 부분적으로 실천되어 왔지만, 자연에 대한 연구과정이 서로 분산된 영역에서 진행되어왔다. 최근에 이르러서 이러한 연구는 관련 분야간에 복합되는 입장에서 매우 중요시되고 있다. 따라서 자연유기체의 다양한 범주들을 본 연구에서는 단지 부분적으로 제품디자인 측면에서 고찰하지만, 종합적으로 디자인학적 조형성과 자연유기체의 조형학적 접근은 기본적으로 중요한 것이라 생각하여 본 소고에서 고찰해 보고자 한다.

• 자원리싸이클링
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• 제14권5호
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• pp.54-61
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• 2005

국내 경제성장과 더불어 발전소 에너지원으로 이용되고 있는 석탄은 매년 증가하여 2006년에는 전체 에너지 구성의 30%인 16,000MW에 이를 것으로 예측되고 있다. 이러한 석탄은 다른 화석연료에 비해 매장량이 풍부하고 경제성은 높지만, 사용이 불편하고 석탄회, 아황산가스 등 많은 공해물질을 배출하고 있다. 따라서 본 연구에서는 마찰하전형정전선별법을 이용하여 석탄과 회분구성 광물의 선별기술을 확립, 청정석탄을 생산하고자 한다. 본 연구에서는 bench-scale의 마찰하전형정전선별 장치를 제작하였으며, 선별에 영향을 미치는 인자들을 선정하고 분리실험을 수행하여 최적조건을 확립하였다. 연구결과 최적조건에서 석탄 회수율과 회분 및 유황분 제거율이 각각 68.10%. 31.23% 그리고 28.33%인 정제석탄을 얻을 수 있었다.