• The Journal of the Korea Contents Association
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• v.20 no.4
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• pp.305-314
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• 2020

Mobile environment is relatively free from time and space constraints, and has unique characteristics such as not applying physical and social vulnerability because of it's non-face-to-face channel. Since such spatial and temporal speciality is likely to appear in a different form from psychological action and action in a general face-to-face environment, it is necessary to conduct an empirical study based on the results of the existing research that has been studied as major psychological variables of action in mobile environment. However, advance research have not been conducted in earnest on the vulnerability and anxiety of the consumers in a new environment called mobile finance. so this study intends to establish the basis through empirical research. As a result, women among traditional vulnerable groups perceived themselves to be vulnerable in mobile financial environments than men and felt fear of crime strongly. In addition, the vulnerability of mobile financial crime did not have a significant direct effect on mobile financial use, but it was confirmed that mobile crime fear was mediated completely and had an indirect effect on mobile financial use.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.17-25
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• 2016

Revetments help protect levee slopes from erosion. If the design of the revetment is not appropriate, the levee may collapse as a result of scouring due to the strong flow velocity and tractive force. Therefore, when designing a revetment, it is very important to calculate the representative velocity. However, the average velocity and depth calculated by 1-D varied flow analysis are generally applied to the design, which do not reflect the increase in velocity caused by the free and force vortex. Therefore, it is necessary to correct the representative velocity in order to ensure the stability of the revetment in a meandering channel. In this study, the applicability of the method of calculating the representative velocity considering the curve and scour was studied (by comparing it with) the average and maximum velocities determined by numerical simulation. The representative velocity corrected for the effect of the curve and scour and the maximum velocity calculated by the numerical simulation were found to match quite well. In addition, the riprap size of the gabion in the meandering and straight channels were compared by applying them to the conventional design formulas. In the future, it is necessary to perform additional numerical simulations for various rivers with different characteristics, in order to propose a method of designing a suitable revetment for Korean characteristics. At this time, the results of this study are expected to be able to be used as basic data.

• Korean Journal of Materials Research
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• v.9 no.10
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• pp.970-977
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• 1999

Effect of Mo interlayer on the relaxation of residual stress in AlN/Cu pint bonded by active-metal brazing method was investigated. The stress analyses by finite-element-method, the measurement of pint strength and the observation of fracture surface were carried out and their results were compared with each other. From the results of stress analysis it is confirmed that a Mo interlayer led to a shift of maximum stress concentration site from AlN/insert-metal interface$\rightarro$ insert-metal/Mo$\rightarro$Mo interlayer. Additionally, with increase of the Mo interlayer thickness the stress concentration with tensile component was separately built both at the interface of Cu/Mo and AlN/Mo. whereby the residual stress in the free surface of AlN close to the bonded interface was drastically reduced. The AlN/Mo/Cu pints with Mo interlayer thickness of above 400$\mu\textrm{m}$ showed the strengths higher than 200 MPa. upto max. 275 MPa, while the AlN/Cu pint only max. 52 MPa.

• Polymer(Korea)
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• v.33 no.4
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• pp.284-289
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• 2009

The morphology and mechanical properties of epoxy/polyamide/MPD reactive blends with various amount of polyamide were investigated. The cure behaviors, mechanical strengths, and morphological changes of the epoxy blend systems were analyzed by using DSC, UTM, and SEM, respectively. The amount of high soluble polyamide in epoxy ranged from 0 to 30 phr, and the cure reaction occurred at $170^{\circ}$ for 30 min. The start and maximum exothermic temperature in heat flows during cure reactions appeared at almost same temperature, indicating that soluble polyamide could rarely hinder the cure reactions. From the SEM images, it was found that the size of separated-phase was very fine about 100-300 nm, and at 20 phr of polyamide the boundary of separated-phase was unclear and the phase revealed co-continuous. By AP plasma treatment of specimen surface, the adhesion strength was increased by 20% due to enhanced surface free energy. By blending 20 phr of polyamide with epoxy, the adhesion strength was increased by 50% due to co-continuous phase in morphology. By considering the surface treatment of specimen and morphological tuning of the blends, it can be expected that the improvement in toughness and excellent adhesion strength can be achieved in structural adhesive systems.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.351-358
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• 2021

The study was investigated to compare growth characteristics, the antioxidant activity, and the triterpenoid content of two Centella asiatica cultivars ('Giant Tiger Care' and 'Good Tiger Care'). At 41 days after transplanting, lengths of leaf and petiole were significantly longer in 'Good Tiger Care' than in 'Giant Tiger Care'. However, the growth characteristics (leaf area, petiole thickness, petiole length, and weight) were greater in 'Giant Tiger Care' than in 'Good Tiger Care' at 104 days after transplanting (harvest time). Antioxidant activity and total phenol content in four extracts (WE, water extract; HWE, hot water extract; 50E, 50% EtOH extract; 70E, 70% EtOH extract) of the two cultivars were high in 70E of 'Giant Tiger Care'. As a result of the triterpenoids analysis, the major triterpenoids of the two cultivars were identified as madecassoside and asiaticoside. The total triterpenoid content was high in 50E and 70E of 'Giant Tiger Care' and 'Good Tiger Care', respectively but the total triterpenoid content was highest in Good Tiger Care'. However, at the 104 days after planting, the yield of 'Giant Tiger Care' was three times higher than that of 'Good Tiger Care'. In addition, the total triterpenoid content that can be produced in the same cultivation area (3.3m²) was 2.459mg in 50E of 'Giant Tiger Care', which was ~2.2times higher than that of 70E of 'Good Tiger Care' (1.103 mg). Thus, it is considered economical to cultivate 'Giant Tiger Care' which has the highest antioxidant activity and high total triterpenoid production per cultivation area.