• 한국응용곤충학회지
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• 제48권1호
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• pp.73-79
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• 2009

톱다리개미허리노린재(Riptortus clavatus Thunberg) (Heteroptera: Alydidae)의 집합페로몬은 (E)-2-hexenyl (Z)-3-hexenoate (E2HZ3H), (E)-2-hexenyl (E)-2-hexenoate (E2HE2H) 및 tetradecyl isobutyrate (TI)의 세 성분으로 구성되어 있다. 성충의 나이, 교미여부, 채집시기, 체중, 하루 중 시간대에 따른 이들 성분의 분비변이를 조사하였다. 이 집합페로몬의 분비량은 교미여부와 체중 및 하루 중 시간에 따른 차이가 없었다. 그러나 우화 후 일수가 경과할수록 수컷의 집합페로몬 분비량이 많아졌으며, 4월부터 9월까지 채집된 수컷의 집합페로몬 검출량은 10월에 채집된 수컷의 검출량보다 높았으며, 11월과 12월에 채집된 수컷에서는 집합페로몬이 검출되지 않았다. 이러한 집합페로몬의 분비변이 양상을 톱다리개미허리노린재의 먹이이용 전략 및 휴면현상과 관련지어 고찰하였다.

• 한국정보통신학회논문지
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• 제17권9호
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• pp.2055-2062
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• 2013

범죄 증거의 새로운 형태인 디지털 증거는 기존의 증거와 기능 및 역할에 있어서 거의 차이점이 없으며, 증거로서의 법적 인정 및 역할이 점차 증가할 것으로 예상된다. 포렌식 수사관은 다수의 증거 보유 장치(예, 컴퓨터 시스템, 저장 매체 등)에 저장되어 있는 막대한 양의 데이터로부터, 사건과 관련된 실마리를 찾기 위하여 많은 시간을 소모해야 한다. 따라서 조사 시간을 단축하기 위해서는 잠재적인 관련 증거의 중요성에 근거하여 순서화 및 순위화가 필요하다. 본 연구에서는 포렌식 조사 시에, 정확한 증거를 선정하게 함으로서 증거 분석 우선순위를 결정하는 방법을 제안한다. 제안된 방식은 증거 조사 소요시간, 증거의 가치, 증거간의 연관성 그리고 사건과 시간과의 연관성과 같은 다수의 부정확한 요소가 퍼지 집합 함수를 사용한 의사 결정에 사용되는 다기준 의사 결정에 근거한다.

• 한국정보처리학회논문지
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• 제6권3호
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• pp.589-602
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• 1999

객체 지향 개념에 토대를 둔 어플리케이션 개발에는 여러 가지 이점이 있으나, 그 중 하나로서, 기존 성과물의 재이용을 들 수 있다. 유효한 재이용 수법 중의 하나로서, 본 논문에서는 클래스 계층 구조를 바탕으로 하는 확장 재구성법에 대해 논한다 우선, 클래스 계층 구조를 보다 형식적인 형태로 정의하고 이론적인 논술이 가능토록 하기 위해서, 클래스 계층 구조를 유한 유방향 그래프 형태인 클래스 계층 그래프로 나타낸다 또한, 클래스 계층 그래프간의 순서관계로써 객체 확장관계 를 정의한다. 객체 확장관계를 만족하는 클래스 계층 그래프의 재구성법으로써, 다섯가지 기본조작을 정의하고, 정의된 기본 조작만을 이용하여 클래스계층 그래프를 확장 재구성할 수 있음을 보이기위해, 기본 조작의 정당성 및 완전성을 증명한다. 본 논문에서 제안한 객체 확장관계 및 기본 재구성기법은, 기존의 객체 지향 어플리케이션을 확장 재구성하고자 할 때 이론 적인 토대로서 이용할 수 있다.

• Environmental Analysis Health and Toxicology
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• 제29권
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• pp.16.1-16.9
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• 2014

Objectives Rapid increase in engineered nanoparticles (ENPs) in many goods has raised significant concern about their environmental safety. Proper methodologies are therefore needed to conduct toxicity and exposure assessment of nanoparticles in the environment. This study reviews several analytical techniques for nanoparticles and summarizes their principles, advantages and disadvantages, reviews the state of the art, and offers the perspectives of nanometrology in relation to ENP studies. Methods Nanometrology is divided into five techniques with regard to the instrumental principle: microscopy, light scattering, spectroscopy, separation, and single particle inductively coupled plasma-mass spectrometry. Results Each analytical method has its own drawbacks, such as detection limit, ability to quantify or qualify ENPs, and matrix effects. More than two different analytical methods should be used to better characterize ENPs. Conclusions In characterizing ENPs, the researchers should understand the nanometrology and its demerits, as well as its merits, to properly interpret their experimental results. Challenges lie in the nanometrology and pretreatment of ENPs from various matrices; in the extraction without dissolution or aggregation, and concentration of ENPs to satisfy the instrumental detection limit.

• 산경연구논집
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• 제11권5호
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• pp.7-16
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• 2020

Purpose: Prior studies empirically examine how financial flexibility is related to required returns by using realized returns and considering cash holdings as net debts, but they fail to find consistent results. Conjecturing that inappropriate proxy of required returns and aggregation of cash and debts caused the inconsistent results, this study revisits this topic by using a refined proxy of required returns and separating cash holdings from debts. Research design, data and methodology: This study uses a multivariate regression model to investigate the relationship between required returns on cash holdings and financial leverage. The required returns are estimated using the return decomposition method by vector autoregression model. Empirical tests use US stock market data from1968 to 2011. Results: Empirical results reveal that both cash holdings and leverage are positively related to required returns. The positive relation is stronger in economic downturns than in economic upturns. Conclusions: Three major findings are drawn. First, risky firms prefer large cash balance. Second, information shocks in the realized returns caused failure of prior studies to find consistent positive relationship between leverage and realized returns. Third, cash and leverage are related to required returns in the same direction; therefore, cash cannot be considered as negative debts.

• Natural Product Sciences
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• 제8권2호
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• pp.35-43
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• 2002

Glycosides of herbal medicines, such as glycyrrhizin, ginsenosides, kalopanaxsaponins, rutin and ponicirin, were studied regarding their metabolic fates and pharmacological actions in relation to intestinal bacteria using germ-free, gnotobiotic and conventional animals. When glycyrrhizin (GL) was orally administered, $18{\beta}-glycyrrhetinic\;acid\;(GA)$, not GL, was detected in plasma and intestinal contents of gnotobiotic and conventional rats. However, GA could not be detected in germ-free rats. When GL was incubated with human intestinal bacteria, it was directly metabolized to GA (>95%) or via $18{\beta}-glycyrrhetinic\;acid-3-{\beta}-D-glucuronide$(>5%). Orally administered GL was effective in gnotobiotic and conventional rats for liver injury induced by carbon tetrachloride, but was not effective in germ-free rats. When ginseng saponins were orally administered to human beings, compound K in the plasma was detected, but the other protopanxadiol saponins were not detected. The compound K was active for tumor metastasis and allergy. When kalopanaxsaponins were incubated with human intestinal microflora, they were metabolized to kalopanaxsaponin A, kalopanaxsaponin I and hederagenin. These metabolites were active for rheumatoid arthritis and diabetic mellitus while the other kalopanxsaponins were not. When flavonoid glycosides were orally administered to animals, aglycones and/or phenolic acids were detected in the urine. The metabolic pathways proceeded by intestinal bacteria rather than by liver or blood enzymes. These metabolites, aglycones and phenolic acids, showed antitumor, antiinflammatory and antiplatelet aggregation activities. These findings suggest that glycosides of herbal medicines are prodrugs.

• 한국환경농학회지
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• 제26권4호
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• pp.279-285
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• 2007

Soil physical properties in organic farming apple orchard were evaluated in relation to conventional farming to better understand the effects of organic farming system on soil quality. Two adjacent apple orchards, matched by soil type, were chosen to ensure the same pedological conditions except management system. Soil samples were collected from middle of two adjacent trees along the tree line at two depths of 5-20 and 20-35 cm in September 2006. Contents of organic matter in organic farming soil were twice as much as those found in soil of conventional farming. The higher level of organic matter in organic farming soil was reflected through a consequent trend in improved soil physical properties. Organic farming produced greater aggregation in >2 mm size and increased aggregate stability. Bulk density was lower by 13% and hence porosity was higher in soils of organic farming as compared with conventional farming. Water holding capacity was significantly greater with organic farming by >17% over conventional farming. The capacity of organic farming to improve soil physical properties can be contributed to the regular application of relatively large amount of organic materials and the sustainable ground-cover managements, mulching with compost and cover crop cultivation.

• Archives of Pharmacal Research
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• 제23권2호
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• pp.172-173
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• 2000

The relationship between the metabolites of glycyrrhizin (18$\beta$-glycyrrhetinic acid-3-O--D-glu-curonopyranosyl-($1{\rightarrow}2$)-$\beta$-D-glucuronide, CL) and their biological activities was investigated. By human intestinal microflora, CL was metabolized to 18$\beta$-glycyrrhetinic acid (GA) as a main product and to 18$\beta$-glycyrrhetinic acid-3-O-$\beta$-D-glucuronide (GAMG) as a minor product. The former reaction was catalyzed by Eubacterium L-8 and the latter was by Streptococcus LJ-22. Among GL and its metabolites, GA and GAMG had more potent in vitro anti-platelet aggregation activity than GL. GA also showed the most potent cytotoxicity against tumor cell lines and the potent inhibitory activity on rotavirus infection as well as growth of Helicobacter pylori. GAMG, the minor metabolite of GL, was the sweetest.

• Journal of Applied Biological Chemistry
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• 제63권3호
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• pp.235-241
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• 2020

An essential component of the hemostatic process during vascular damage is platelet activation. However, many cardiovascular diseases, such as atherosclerosis, thrombosis, and myocardial infarction, can develop due to excessive platelet activation. Isoscopoletin, found primarily in plant roots of the genus Artemisia or Scopolia, has been studied to demonstrate potential pharmacological effects on Alzheimer's disease and anticancer, but its mechanisms and role in relation to thrombus formation and platelet aggregation have not yet been discovered. This research investigated the effect of isoscopoletin on collagen-induced human platelet activation. As a result, isoscopoletin strongly increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in a concentration-dependent manner. In addition, isoscopoletin greatly phosphorylated inositol 1,4,5-triphosphate receptor (IP₃R) and vasodilator-stimulated phosphoprotein (VASP), known substrates of cAMP-dependent kinase and cGMP dependent kinase. Phosphorylation of IP₃R by isoscopoletin induced Ca²⁺ inhibition from the dense tubular system Ca²⁺ channels, and VASP phosphorylation was involved in fibrinogen binding inhibition by inactivating αIIb/β₃ in the platelet membrane. Isoscopoletin finally reduced thrombin-induced fibrin clot production and finally reduced thrombus formation. Therefore, this research suggests that isoscopoletin has strong antiplatelet effects and is likely to be helpful for thrombotic diseases involving platelets by acting as a prophylactic and therapeutic agent.

• Archives of Pharmacal Research
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• 제21권1호
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• pp.17-23
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• 1998

Flavonoid glycosides were metabolized to phenolic acids via aglycones by human intestinal microflora producing ${\alpha}$-rhamnosidase, exo-${\beta}$-glucosidase, endo- ${\beta}$-glucosidase and/or ${\beta}$-glucuronidase. Rutin, hesperidin, naringin and poncirin were transformed to their aglycones by the bacteria producing ${\alpha}$-rhamnosidase and ${\beta}$-glucosidase or endo- ${\beta}$-glucosidase, and baicatin, puerarin and daidzin were transformed to their aglycones by the bacteria producing ${\beta}$glucuronidase, C-glycosidase and ${\beta}$-glycosidase, respectively. Anti-platelet activity and cytotoxicity of the metabolites of flavonoid glycosides by human intestinal bacteria were more effective than those of the parental compounds. 3,4-Dihydroxyphenylacetic acid and 4-hydroxyl-phenylacetic acid were more effective than rutin and quercetin on anti-platelet aggregation activity. 2,4,6-Trihydroxybenzaidehyde, quercetin and ponciretin were more effective than rutin and ponciretin on the cytotoxicity for tumor cell lines. We insist that these flavonoid glycosides should be natural prodrugs.