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여지윤,이충현,박소영 한국생약학회 2021 생약학회지 Vol.52 No.1
As the consumption of avocado fruits and avocado oils is steadily increasing, the amount of avocado seeds which are thrown away as by-products is also inceasing. Thus, the possibility of use of avocado seeds as natural preservatives was studied focused on the antioxidant effect. The extraction of avocado seeds and seed husks with 100% ethanol by maceration showed highest antioxidant activities and lowest IC50 values compared to 80% ethanol extract. Furthermore, 100% ethanol extract of avocado seeds and seed husks included significantly higher amount of polyphenols than 80% extract. However, total flavonoid content of 100% avocado seed extract was not signigicantly different from 80% seed extract, whereas that of 100% avocado seed husk extract was significantly higher than 80% seed husk extract. In case of acid values, heating of oil alone for 120 and 180 min significantly increased the acid values, whereas the treatment of oil with seed and seed husk extract signficantly decreased the acid values. These results suggest that antioxidant effects of avocado seeds and seed husks protected the oil against heat-induced acidification. Thus, avocado seeds and seed husks have a potential to be developed as an natural antioxidant and natural preservative which could be used commercially.
자소엽에서 분리된 트리테르페노이드의 베타-아밀로이드 응집 억제 효과
여지윤,이충현,박소영 한국생약학회 2020 생약학회지 Vol.51 No.4
Perilla frutescens Britton var. acuta Kudo, an annual plant primarily cultivated in China, Japan, and Korea, has been used as a traditional medicine to treat inflammatory diseases, depression, and many anxiety-related disorders. Previously, we reported the inhibitory effects of n-hexane layer of P. frutescens var. acuta extract against beta-amyloid (Aβ) aggregation, and the isolation of asarone derivatives as active constituents from n-hexane layer. In this study, dichloromethane layer of P. frutescens var. acuta was applied to bioassay-guided isolation methods accompanied with Thioflavin T (Th T) fluorescence assay to investigate the inhibitory effect on Aβ aggregation and disaggregation. As the results, three triterpenoids including ursolic acid (1), tormentic acid (2) and corosolic acid (3) were isolated. All compounds reduced Aβ aggregation and increased disaggregation of preformed Aβ aggregates in a dose-dependent manner. However, the inhibitory effect of three compounds on Aβ aggregation was not correlated with antioxidant activity, which was measured by DPPH assay. Taken together, these results suggest that the triterpenoid derivatives from P. frutescens have the potential to be developed as good therapeutics or preventatives for AD.
적층제조된 알루미늄 합금의 공정변수 및 합금조성이 상대밀도와 기계적 특성에 미치는 영향도 분석
박수원,여지윤,한송윤,최현주 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
Metal additive manufacturing (AM) has transformed conventional manufacturing processes by offering unprecedented opportunities for design innovation, reduced lead times, and cost-effective production. Aluminum alloy, a material used in metal 3D printing, is a representative lightweight structural material known for its high specific strength and corrosion resistance. Consequently, there is an increasing demand for 3D printed aluminum alloy components across industries, including aerospace, transportation, and consumer goods. To meet this demand, research on alloys and process conditions that satisfy the specific requirement of each industry is necessary. However, 3D printing processes exhibit different behaviors of alloy elements owing to rapid thermal dynamics, making it challenging to predict the microstructure and properties. In this study, we gathered published data on the relationship between alloy composition, processing conditions, and properties. Furthermore, we conducted a sensitivity analysis on the effects of the process variables on the density and hardness of aluminum alloys used in additive manufacturing.
김범수,여지윤 고려대학교 미래성장연구원 2019 미래성장연구 Vol.5 No.2
본 연구는 2008년부터 시행된 신생아 집중치료 지역센터 지원사업으로 인한 신생아 집중 치료실 병상 수의 증가가 실제로 출생아의 4주 내 사망률과 1년 내 사망률을 낮추는지 확인하기 위해 이루어졌다. 통계청 출생 자료와 사망자료, 그리고 건강보험심사평가원이 제공한 병상수 자료를 이용하여 분석하였으며 정책 시행 지역 중 지원 시설 이외의 신생아 집중 치료실 병상수의 변화가 없는 제주와 울산 지역을 분석함으로써 신생아집중치료실의 변화를외생적으로 처리하였다. 이항 로지스틱 회귀모델을 이용하였으며 종속변수는 출생아의 4주내 사망률과 1년 내 사망률이다. 두 지역에서는 병상수가 10% 증가하면 전체 출생아 4주내 사망률과 1년 내 사망률이 3% 와 4% 각각 하락하였다. 신생아 집중치료실의 수요가 높은 미숙아나 초저체중아 그룹을 살펴보면 사망률은 12~18% 감소하여 그 효과가 훨씬 큰것으로 나타났다. 하지만, 정책 개입으로 병상수가 늘어나면 같은 지역의 다른 병원에서 병상수가 감소하는 구축효과가 발생하는 경우도 확인되었다.
Multi-feeder 3차원 적층제조 기반 조합실험을 활용한 알루미늄 합금탐색
박수원,송용욱,여지윤,한송윤,최현주 한국분말재료학회 2023 한국분말재료학회지 (KPMI) Vol.30 No.3
Aluminum alloys are widely utilized in diverse industries, such as automobiles, aerospace, and architecture, owing to their high specific strength and resistance to oxidation. However, to meet the increasing demands of the industry, it is necessary to design new aluminum alloys with excellent properties. Thus, a new method is required to efficiently test additively manufactured aluminum alloys with various compositions within a short period during the alloy design process. In this study, a combinatory approach using a direct energy deposition system for metal 3D printing process with a dual feeder was employed. Two types of aluminum alloy powders, namely Al6061 and Al-12Cu, were utilized for the combinatory test conducted through 3D printing. Twelve types of Al-Si-Cu-Mg alloys were manufactured during this combinatory test, and the relationship between their microstructures and properties was investigated.