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Analysis of Orbital Lifetime Prediction Parameters in Preparation for Post-Mission Disposal
최하연,김해동,성재동 한국우주과학회 2015 Journal of Astronomy and Space Sciences Vol.32 No.4
Atmospheric drag force is an important source of perturbation of Low Earth Orbit (LEO) orbit satellites, and solar activity is a major factor for changes in atmospheric density. In particular, the orbital lifetime of a satellite varies with changes in solar activity, so care must be taken in predicting the remaining orbital lifetime during preparation for post-mission disposal. In this paper, the System Tool Kit (STK®) Long-term Orbit Propagator is used to analyze the changes in orbital lifetime predictions with respect to solar activity. In addition, the STK® Lifetime tool is used to analyze the change in orbital lifetime with respect to solar flux data generation, which is needed for the orbital lifetime calculation, and its control on the drag coefficient control. Analysis showed that the application of the most recent solar flux file within the Lifetime tool gives a predicted trend that is closest to the actual orbit. We also examine the effect of the drag coefficient, by performing a comparative analysis between varying and constant coefficients in terms of solar activity intensities.
Exploring Restaurant Selection Attributes of Vegetarian Customers
최하연,정현우 (사)한국조리학회 2018 한국조리학회지 Vol.24 No.7
The current study examined attributes that vegetarian customers consider when they dine out. By determining those attributes, we can determine what non-vegetarian restaurants can do to attract vegetarian/vegan customers. The online-based questionnaire was developed and distributed through the online survey company (www.Qualtrics.com). All data were compiled and analyzed using IBM SPSS v 22. A total of 360 questionnaires was used for data analysis. An exploratory factor analysis identified eight factors, explaining 66.34% of the variance. Eight factors were labeled as 1) social media marketing, 2) food quality, 3) service quality, 4) vegetarian/nutritious menu, 5) value for money, 6) atmosphere, 7) reputation, and 8) promotions. The findings of the current study indicated that food quality and value for money service are most important. However, as the findings indicated, vegetarian menu (M=3.99 out of 5) is considered to be one of the important restaurant selection attributes among vegetarian customers. Given the fact that the number of (semi-)vegetarians are increasing tremendously over the past decades, industry practitioners should be prepared for the trends to be successful in the competitive marketplace. To our knowledge, the current study was the first attempt exclusively investigated restaurant selection attributes of vegetarian customers when dining out. The findings of the current study will shed light on the better understanding of vegetarian customers’ perceptions, attitudes, and behavior.
캠벨얼리(Vitis labruscana B.) 잎 에탄올 추출물이 신경세포에서 아밀로이드 전구 단백질의 발현과 아세틸콜린에스테라제 활성에 미치는 영향
최하연,김주은,마상용,조형권,김대성,임재윤,Choi, Ha Yeon,Kim, Ju Eun,Ma, Sang Yong,Cho, Hyung Kwon,Kim, Dae Sung,Leem, Jae Yoon 한국생약학회 2022 생약학회지 Vol.53 No.2
Alzheimer's disease (AD) is the most common form of dementia, and the accumulation of β-amyloid (Aβ) in the brain triggers AD, followed by hyperphosphorylation of tau protein, neurofibrillary tangles, and synapses loss, neuronal cell death, and cognitive decline occur in a chain. In APPswe neuronal cell line, 50 ㎍/ml of Campbell early (Vitis labruscana B.) leaves 50% ethanol extract (VLL) treatment inhibited the secretion of Aβ1-42 by about 63% and the secretion of Aβ1-40 by about 50%. VLL did not target the enzymatic activity of the amyloidogenic pathway and decreased the protein expression of APP. As a result of RT-qPCR (Reverse transcription-quantitative real-time PCR) of the APPswe cell line treated with VLL, it is thought that the protein expression of APP was reduced by inhibiting the transcription process of the APP gene. In addition, VLL inhibited acetylcholinesterase (AChE) enzyme activity in vitro by 27.6% and 54.7%, respectively, at 50 and 100 ㎍/ml concentrations. We found that VLL inhibited the production of Aβ, a dementia-inducing substance, by suppressing the transcription of the APP gene, and that VLL inhibited AChE activity. We suggest that VLL has the potential as a natural drug material that modulates the alleviation of dementia symptoms.