• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.2
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• pp.23-36
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• 2005

The main obstacle hindering the wide deployment of identity-based cryptosystem is that the entity responsible for creating the private key has too much power. As a result, private keys are no longer private. One obvious solution to this problem is to apply the threshold technique. However, this increases the authentication computation, and communication cost during the key issuing phase. In this paper, we propose a new effi ient model for issuing multiple private keys in identity-based encryption schemes based on the Weil pairing that also alleviates the key escrow problem. In our system, the private key of a user is divided into two components, KGK (Key Description Key) and KUD(Key Usage Desscriptor), which are issued separately by different parties. The KGK is issued in a threshold manner by KIC (Key Issuing Center), whereas the KW is issued by a single authority called KUM (Key Usage Manager). Changing KW results in a different private key. As a result, a user can efficiently obtain a new private key by interacting with KUM. We can also adapt Gentry's time-slot based private key revocation approach to our scheme more efficiently than others. We also show the security of the system and its efficiency by analyzing the existing systems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.2
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• pp.77-84
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• 2021

A sampling-based approach was devised as a nuclear seismic probabilistic risk assessment (SPRA) method to account for the partially correlated relationships between components. However, since this method is based on sampling, there is a limitation that a large number of samples must be extracted to estimate the results accurately. Thus, in this study, we suggest an effective approach to improve the existing sampling method. The main features of this approach are as follows. In place of the existing Monte Carlo sampling (MCS) approach, the Latin hypercube sampling (LHS) method that enables effective sampling in multiple dimensions is introduced to the SPRA method. In addition, the degree of segmentation of the seismic intensity is determined with respect to the final seismic risk result. By applying the suggested approach to an actual nuclear power plant as an example, the accuracy of the results were observed to be almost similar to those of the existing method, but the efficiency was increased by a factor of two in terms of the total number of samples extracted. In addition, it was confirmed that the LHS-based method improves the accuracy of the solution in a small sampling region.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.1
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• pp.85-92
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• 2021

The stratum corneum is formed from keratinocytes and intercellular lipids, with ceramide as the main component of intercellular lipids. Ceramides are one of the important components of the intercellular lipids to form a lamellar structure, but they are insoluble and therefore are not suitable for direct application to the skin. Thus, it was intended to apply ceramide to the formulation of pluronic lecithin organogel (PLO gel), which received constant attention among drug delivery systems. A suitable oil for formulation was selected and a PLO gel containing ceramide was manufactured. Liquid crystal formation and variation were observed using polarized microscopes, and viscoelastic analysis was performed to find out the viscoelastic behavior of the PLO gel. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) analysis were performed to confirm the structures in the formulation. Results showed that the size and stability of the liquid crystal differed depending on the content ratio of ceramide and lecithin in the PLO gel containing ceramide. Furthermore, viscoelastic analysis showed the stability of the formulation, and SAXS/WAXS analysis confirmed that the PLO gel without ceramide had hexagonal structure of the quadrilateral system array, and the PLO gel with ceramide had the lamellar structure of the quadrilateral system array.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.7
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• pp.445-454
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• 2022

Ice accretion on the aircraft components, such as wings, fuselage, and empennage, can occur when the aircraft encounters a cloud zone with high humidity and low temperature. The prevention of ice accretion is important because it causes a decrease in the aerodynamic performance and flight stability, thus leading to fatal safety problems. In this study, a shape design optimization of a multi-element airfoil is performed to minimize the amount of ice accretion on the high-lift device including leading-edge slat, main element, and trailing-edge flap. The design optimization framework proposed in this paper consists of four major parts: air flow, droplet impingement and ice accretion simulations and gradient-free optimization algorithm. Reynolds-averaged Navier-Stokes (RANS) simulation is used to predict the aerodynamic performance and flow field around the multi-element airfoil at the angle of attack 8°. Droplet impingement and ice accretion simulations are conducted using the multi-physics computational analysis tool. The objective function is to minimize the total mass of ice accretion and the design variables are the deflection angle, gap, and overhang of the flap and slat. Kriging surrogate model is used to construct the response surface, providing rapid approximations of time-consuming function evaluation, and genetic algorithm is employed to find the optimal solution. As a result of optimization, the total mass of ice accretion on the optimized multielement airfoil is reduced by about 8% compared to the baseline configuration.

• Journal of Ginseng Research
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• v.46 no.6
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• pp.738-749
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• 2022

Background: Ginseng possesses antitumor effects, and ginsenosides are considered to be one of its main active chemical components. Ginsenosides can further be hydrolyzed to generate secondary saponins, and 20(R)-panaxotriol is an important sapogenin of ginsenosides. We aimed to synthesize a new ginsengenin derivative from 20(R)-panaxotriol and investigate its antitumor activity in vivo and in vitro. Methods: Here, 20(R)-panaxotriol was selected as a precursor and was modified into its derivatives. The new products were characterized by ¹H-NMR, ¹³C-NMR and HR-MS and evaluated by molecular docking, MTT, luciferase reporter assay, western blotting, immunofluorescent staining, colony formation assay, EdU labeling and immunofluorescence, apoptosis assay, cells migration assay, transwell assay and in vivo antitumor activity assay. Results: The derivative with the best antitumor activity was identified as 6,12-dihydroxy-4,4,8,10,14-pentamethyl-17-(2,6,6-trimethyltetrahydro-2H-pyran-2-yl)hexadecahydro-1H-cyclopenta[a]phenanthren-3-yl(tert-butoxycarbonyl)glycinate (A11). The focus of this research was on the antitumor activity of the derivatives. The efficacy of the derivative A11 (IC₅₀ < 0.3 µM) was more than 100 times higher than that of 20(R)- panaxotriol (IC₅₀ > 30 µM). In addition, A11 inhibited the protein expression and nuclear accumulation of the hypoxia-inducible factor HIF-1α in HeLa cells under hypoxic conditions in a dose-dependent manner. Moreover, A11 dose-dependently inhibited the proliferation, migration, and invasion of HeLa cells, while promoting their apoptosis. Notably, the inhibition by A11 was more significant than that by 20(R)-panaxotriol (p < 0.01) in vivo. Conclusion: To our knowledge, this is the first study to report the production of derivative A11 from 20(R)-panaxotriol and its superior antitumor activity compared to its precursor. Moreover, derivative A11 can be used to further study and develop novel antitumor drugs.

• Journal of the Korean Applied Science and Technology
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• v.39 no.5
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• pp.692-700
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• 2022

In this study, the effect of e-service quality of O2O cosmetic delivery service app on satisfaction and loyalty was investigated. To this end, a total of 210 questionnaires were collected and frequency analysis, exploratory factor analysis, reliability analysis, correlation analysis, and regression analysis were performed using the statistical package SPSS 25.0. The main results are as follows. Efficiency, order fulfillment, system availability, and privacy, which are components of O2O cosmetic delivery service app e-service quality, all had a significant effect on satisfaction and loyalty. Also, satisfaction was found to have a significant effect on loyalty. In order to increase the number of consumers who use the O2O cosmetic delivery service app, it is necessary to increase the availability and efficiency of the system, which has the greatest impact on satisfaction and loyalty. To this end, it is necessary to provide a comfortable environment without interruption and fast access while using the O2O cosmetic delivery service app, and to build a system so that it can be used efficiently.

• Conservation Science in Museum
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• v.28
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• pp.17-34
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• 2022

This study seeks to identify the material characteristics of earthenware excavated from the Bangi-dong Ancient Tomb No. 3 and the articulated stone-mound tomb of the Seokchon-dong ancient tombs in the Songpa region, and analyze the homogeneity and the firing temperature of the materials used at each excavated site. The remains have been studied relatively recently, and the groups of tombs in which they were found demonstrate the transition of ancient Korean burial systems, and at the same time, provide important archaeological data about those in power at the time. The earthenware pottery excavated from the two sites examined in the study were buried at different times, and it is assumed that they were made by procuring weathered soil of similar gneiss, judging from the behavior of the compatible and incompatible elements and the weathering tendency found by examining the main components. In addition, the examination of the mineral composition and microstructure of clay indicates that the earthenware from Seokchon-dong was fired at 950 degrees Celsius or lower at a relatively early stage. On the other hand, the earthenware from Bangi-dong Tomb No. 3 was confirmed to have experienced temperatures below 850 degrees Celsius and above 1,000 degrees Celsius. However, it is difficult to interpret the difference as the result of the changes in firing temperature throughout the eras. It is expected that it will be possible to interpret the changes in earthenware manufacturing techniques by comparing more diverse earthenware potteries and ancient soils.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.40 no.4
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• pp.49-57
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• 2022

This study was conducted with the aim of investigating the garden architectural characteristics of Villa d'Este, which occupies a major role in the exploration of the contrasting background, location, and spatial composition characteristics of Italian Renaissance gardens. The survey for the study was divided into a literature survey and a field survey, and the details are as follows. First, in the mid-to-late 16th century, the villa was built under the direction of Cardinal Ippolito d'Este, and afterwards, the ownership of the villa was restored to the Italian government in 1850 due to financial difficulties. The Villa d'Este, which suffered another damage, is now operated with many visitors after going through the restoration process. Second, in the case of location, it has the characteristics of Urbana located in the city center and has valley-type topographical conditions located at the foot of the mountain.Third, in the case of spatial composition, it is orthogonal to the axis, and each part of the garden is developed, influenced by the contrast principles such as the installation of the Cortile del Belvedere and Villa Madama in the early 16th century. The main building is located in the hills so that you can see the garden and the surrounding scenery at a glance. Fourth, among the components, there were stairs, logia, courtyard, and grotto, fountains, cascades, ponds, and vegetation such as laurels, thorn trees.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.593-615
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• 2022

This study aimed to analyze the relationship between the observation ability and scientific creativity of elementary students through observation learning of outdoor plants and to identify the factors that influence the two constructs. The study recruited 21 fifth-graders in Seoul. After evaluating observation ability and scientific creativity through observation tasks, qualitative data were obtained through interviews with students about their observation of the plants. Additionally, the study collected various materials, such as the observation records and worksheets of the students to verify the validity of research. The main results of this study are as follows. First, the students were first classified into four groups according to levels of observation ability and scientific creativity. The result demonstrated that the higher the level of observation ability, the higher the level of scientific creativity. Second, observation ability and scientific creativity pointed to a positive correlation. Furthermore, originality, which is one of the components of scientific creativity, indicated a weak positive correlation with observation ability. Third, the factors that influenced observation ability were frequency of plant observation and interest and cooperation in observation learning, and those of scientific creativity were observation ability and the level of plant-related knowledge. Lastly, the study discussed educational methods for improving observation ability and scientific creativity.

• Journal of Mushroom
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• v.20 no.4
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• pp.218-226
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• 2022

Flammulina velutipes, known as winter mushroom in the family of Physalacriaceae, is the main edible and export mushroom with the third highest production after oyster and king oyster mushroom in Korea. However, as normal consumers regard F. velutipes as a simple subsidiary material, there is a limitation to increasing mushroom demand. In order to overcome the consumption limit and increase the differentiation of new varieties, it is necessary to breed varieties with enhanced functionality in consideration of consumer preferences. Therefore, the study was performed to analyze nutrient components and several useful functional substances with 26 genetic resources of F. velutipes. Analyses of inorganic compound(Ca, K, Mg) and 15 amino acids revealed that Strain 4148 had the highest content among the 26 strains. Beta-glucan, which increases immune activity and polyphenol, which exert antioxidant effects were higher in non-white strains than in white strains with a small number of exceptions. Among the five fatty acids, linoleic acid(an omega-6 fatty acid) and α-linolenic acid(an omega-3 fatty acid), were detected in six mushroom strains. α-linolenic acid, which was not found in five major mushrooms including oyster mushrooms, was identified in F. velutipes. The results of HPLC analysis showed that 'Auram' (Strain 4232) and 'Baekseung'(Strain 4230) had the highest content of the stabilizing neurotransmitter GABA(15.38 ㎍/ml and 20.56 ㎍/ml, respectively) among non-white and white strains, respectively. Our findings provide useful information for breeding F. velutipes to obtain strains with enhanced functionality.