• Advances in nano research
• /
• v.14 no.5
• /
• pp.463-474
• /
• 2023

The purpose of this paper is to present the analysis of propagating and evanescent waves in functionally graded (FG) nanoplates with the consideration of nonlocal effect. The analytical integration nonlocal stress expansion Legendre polynomial method is proposed to obtain complete dispersion curves in the complex domain. Unlike the traditional Legendre polynomial method that expanded the displacement, the presented polynomial method avoids employing the relationship between local stress and nonlocal stress to construct boundary conditions. In addition, the analytical expressions of numerical integrations are presented to improve the computational efficiency. The nonlocal effect, inhomogeneity of medium and their interactions on wave propagation are studied. It is found that the nonlocal effect and inhomogeneity of medium reduce the frequency bandwidth of complex evanescent Lamb waves, and make complex evanescent Lamb waves have a higher phase velocity at low attenuation. The occurrence of intersections of propagating Lamb wave in the nonlocal homogeneous plate needs to satisfy a smaller Poisson's ratio condition than that in the classical elastic theory. In addition, the inhomogeneity of medium enhances the nonlocal effect. The conclusions obtained can be applied to the design and dynamic response evaluation of composite nanostructures.

• Journal of Information Technology Applications and Management
• /
• v.31 no.3
• /
• pp.71-92
• /
• 2024

This study investigates the contribution of customer knowledge to customer intention to adopt mobile banking by evaluating the interaction among knowledge, perceived risk and trust, and behavioral intentions. Analysis is conducted through structural equation modelling using SPSS and AMOS and data from 783 customers representing the seven largest banks in Vietnam. Our study is the first one to find the existence of the bidirectional perspective between objective and subjective knowledge. The study further shows that the attenuation effect in the heuristic-systematic model could be used to explain the stronger influence of objective knowledge on intention compered to subjective knowledge. Our findings suggest that customer knowledge, perceived risk and trust impact the intention of mobile banking users in different manners and to different degrees. Particularly, objective customer knowledge is the most influential predictor of mobile banking adoption. Having a greater understanding of these relationships can help firms in deciding the kind of intervention that is most likely to convince customers to adopt a service.

• Journal of Korean Society for Atmospheric Environment
• /
• v.11 no.E
• /
• pp.23-29
• /
• 1995

Relationship between atmospheric aerosol transmissivity and air pollution was analyzed using observed data in a large industrial city, Pusan, Korea. The atmospheric aerosol transmissivity predicted by method of present study in Pusan was assessed by the method of Yamamoto et al.(1968) in order to set up an empirical model to predict the transmissivity using the various meteorological parameters and air pollution. As a result, good correlation between these tow method re observed. Thus, it is possible to conclude that the parameterization of air pollution suggested by this study is another method to give reliable estimate of atmospheric aerosol transmissivity and direct solar irradiance in Pusan.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.12
• /
• pp.1078-1085
• /
• 2011

In this paper, we analyze the relationship between energy per bit and the data rate with the variation of the system bandwidth. A existing power model is mathematical model to express power consumption of each device. In this paper, we have to investigate the system level energy model for the RF front-end of a wireless transceiver. Also, the effects of the signal bandwidth, PAR, date rate, modulation level, transmission distance, specific attenuation of frequency band, and the signal center frequency on the RF front-end energy consumption and system capacity are considered. Eventually, we analyze the relationship between energy per bit and the data rate with the variation of the system bandwidth so that we simulate the minimum energy per bit in the several Gbps data rate using Shannon capacity theory.

• 한국해양학회지
• /
• v.26 no.1
• /
• pp.59-66
• /
• 1991

Laboratory studies were carried out to measure the sound velocity (V/SUB p/) and quality factor (Q/SUB p/, inverse attenuation) in the horizontal (H) and vertical (V) direction on the core sampled sediment of deep-sea basin (1,850 meter water depth), East Sea of Korea (Sea of Japan). Sampled core was about 250 cm long and 500 kHz ultrasonic p-wave transducer was used for a sound soured. V/SUB p/ varies from 1,480 m/sec to 1,500 m/sec, it is not clear which direction is faster, V/SUB PH/ or V/SUB pv/, within${\pm}$ 1.0% anisotropy (A/SUB p/). It is thought because the core sediment facies is highly (or slightly) bioturbated homogeneous mud with very high porosity (more than 80%). The general trend of Q/SUB p/ is decreasing 10 to 5 with the buried depth, it is strongly affected by the variation of sediment texture (increasing silt, decreasing clay) with increasing of CaCO$_3$ and organic matter content, But Q/SUB PH/ is jumping up to 14.9 near the bottom of core sediment as including volcanic ash richly. The relationship between V/SUB PH/ and Q/SUB PH/ shows the mirror image nearly, it is interpreted that not only the geotechnical properties and texture but also sea-water characteristics (high Q/SUB p/, low V/SUB p/) according to rich water content affect strongly in the upper part of the unconsolidated deep-sea basin sediment.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.27 no.6
• /
• pp.771-781
• /
• 1994

Monthly measurements made at 15 stations along the axis of the upper Neuse River estuary show a highly variable degree of correlation between concentration of suspended particulate material (SPM) and attenuation coefficient (c) of light as measured by transmissometer. Coefficients of determination along transect lines ranged from $0.12{\sim}0.93$ and calibration slopes ranged from $0.50{\sim}5.63$. When examined on a station-by-station basis, coefficients of determination ranged from $0.21{\sim}0.96$ and calibration slopes ranged from $1.04{\sim}4.94$. Surface calibrations made at individual stations over the full 13-month period were the most consistent of all observations and were considerably better than calibrations made using all of the stations on a given day. Organic content, which can dominate the suspended sediment load during some months, does not appear to explain the variations in reliability of the calibrations. However, an abundance of large aggregates with time-varying size and shape distributions may be partly responsible for variations in optical properties of the sediments, and thus may confound the relationship between SPM and c in the Neuse River estuary Time-varying calibrations to account for non-negligible changes in optical properties may not suffice in complex estuarine environments where the in situ particle dynamics are poorly understood. However, the best use of Beam Transmissometer will continue to be for applications such as detecting water-column events or for use in situations where wide error bars in establishing SPM concentrations are acceptable.

• Korean Journal of Community Nutrition
• /
• v.14 no.5
• /
• pp.590-599
• /
• 2009

The purpose of this study was to analyze the relationship of nutritional status measured by the body composition and dietary nutrients intakes with calcaneal broadband ultrasound attenuation in college students. Total of 886 (462 male and 424 female) students who received health examination in May 2007 participated in this research. Participants bone status was measured by a quantitative ultrasound method and t-score was calculated via WHO guideline. For body composition measurements, body fat, height and weight were measured and BMI was calculated. Dietary data were collected by a 24-hour recall method. Based on Asia-Pacific standard of WHO, BMI was divided into 3 groups; UW (BMI < 18.5), NW + OW (18.5 $\leqq$ BMI < 25) and Obese group (25 $\leqq$ BMI). Among male students, 2.4% belong to the UW group, 45.0% to the NW+OW group and 52.6% belong to the obese group, bwhile 10.4% of female students belong to the UW group, 71.9% to the NW + OW group and 17.7% of female students belong to the Obese group. Differences among male and female students were statistically significant (p < 0.001). Students with higher BMI showed significantly higher bone health status. Male students did not show any significant differences in nutrients intakes by BMI groups while female students showed the higher intakes of energy, protein, pyridoxin, phosphorus, iron and zinc among NW + OW group than other groups (p < 0.05). The qualitative and quantitative evaluation of diet by BMI groups did not show any significant differences in both male and female students. The result of the multiple regression analyses showed that the body fat and bone status was negatively related while energy intake was positively related with the bone status. These results revealed that bone health status was positively affected by BMI but not by body fat. In conclusion, among those who are at their twenties, the period when the bone density becomes maximized, body fat may negatively affect bone health unlike during other life cycle stages.

• Journal of Intelligence and Information Systems
• /
• v.23 no.2
• /
• pp.19-38
• /
• 2017

Collaborative filtering (CF) algorithm has been popularly used for implementing recommender systems. Until now, there have been many prior studies to improve the accuracy of CF. Among them, some recent studies adopt 'hybrid recommendation approach', which enhances the performance of conventional CF by using additional information. In this research, we propose a new hybrid recommender system which fuses CF and the results from the social network analysis on trust and distrust relationship networks among users to enhance prediction accuracy. The proposed algorithm of our study is based on memory-based CF. But, when calculating the similarity between users in CF, our proposed algorithm considers not only the correlation of the users' numeric rating patterns, but also the users' in-degree centrality values derived from trust and distrust relationship networks. In specific, it is designed to amplify the similarity between a target user and his or her neighbor when the neighbor has higher in-degree centrality in the trust relationship network. Also, it attenuates the similarity between a target user and his or her neighbor when the neighbor has higher in-degree centrality in the distrust relationship network. Our proposed algorithm considers four (4) types of user relationships - direct trust, indirect trust, direct distrust, and indirect distrust - in total. And, it uses four adjusting coefficients, which adjusts the level of amplification / attenuation for in-degree centrality values derived from direct / indirect trust and distrust relationship networks. To determine optimal adjusting coefficients, genetic algorithms (GA) has been adopted. Under this background, we named our proposed algorithm as SNACF-GA (Social Network Analysis - based CF using GA). To validate the performance of the SNACF-GA, we used a real-world data set which is called 'Extended Epinions dataset' provided by 'trustlet.org'. It is the data set contains user responses (rating scores and reviews) after purchasing specific items (e.g. car, movie, music, book) as well as trust / distrust relationship information indicating whom to trust or distrust between users. The experimental system was basically developed using Microsoft Visual Basic for Applications (VBA), but we also used UCINET 6 for calculating the in-degree centrality of trust / distrust relationship networks. In addition, we used Palisade Software's Evolver, which is a commercial software implements genetic algorithm. To examine the effectiveness of our proposed system more precisely, we adopted two comparison models. The first comparison model is conventional CF. It only uses users' explicit numeric ratings when calculating the similarities between users. That is, it does not consider trust / distrust relationship between users at all. The second comparison model is SNACF (Social Network Analysis - based CF). SNACF differs from the proposed algorithm SNACF-GA in that it considers only direct trust / distrust relationships. It also does not use GA optimization. The performances of the proposed algorithm and comparison models were evaluated by using average MAE (mean absolute error). Experimental result showed that the optimal adjusting coefficients for direct trust, indirect trust, direct distrust, indirect distrust were 0, 1.4287, 1.5, 0.4615 each. This implies that distrust relationships between users are more important than trust ones in recommender systems. From the perspective of recommendation accuracy, SNACF-GA (Avg. MAE = 0.111943), the proposed algorithm which reflects both direct and indirect trust / distrust relationships information, was found to greatly outperform a conventional CF (Avg. MAE = 0.112638). Also, the algorithm showed better recommendation accuracy than the SNACF (Avg. MAE = 0.112209). To confirm whether these differences are statistically significant or not, we applied paired samples t-test. The results from the paired samples t-test presented that the difference between SNACF-GA and conventional CF was statistical significant at the 1% significance level, and the difference between SNACF-GA and SNACF was statistical significant at the 5%. Our study found that the trust/distrust relationship can be important information for improving performance of recommendation algorithms. Especially, distrust relationship information was found to have a greater impact on the performance improvement of CF. This implies that we need to have more attention on distrust (negative) relationships rather than trust (positive) ones when tracking and managing social relationships between users.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.20 no.2
• /
• pp.119-125
• /
• 1987

Optical properties of sea water were studied in the Sagami Bay, Japan, based on the data obtained from six oceanographic stations in June, 1985. The observation of surface irradiance and underwater irradiance of sea water for eight kind of wavelengths (378, 422, 481, 513, 570, 621, 653, 677 nm) of sun light was conducted using the underwater irradiameter $(Isigawa\;\#\;SR-8)$. The mean attenuation coefficient of the sea water was appeared to be 0.166 $(0.061\~0.644)$ and the attenuation coefficient of the sea water for wavelength appeared such as 0.121 for 378 nm, 0.105 for 422 nm, 0.097 for 481 nm, 0.099 for 513 nm, 0.138 for 570 nm, 0.253 for 621 nm, 0.258 for 653 nm, 0.253 for 677 nm. The transparency was 12.9 m $(7.2\~18m)$, water color was $(5\~10m)$ in the study area and the sun altitude was $70.79^{\circ}\;(57.44^{\circ}\~78.42^{\circ}C)$ The relationship between attenuation coefficient (K) ana transparency (D) was $K=2.87/D(1.06/D\~5.48/D)$. The rates of light penetration for eight kind of wavelenths (378, 422, 481, 513, 570, 621, 653, 677 nm) were computed with reference to the surface light intensity respectively, The mean rate of light penetration in proportion to depths were $77.93\%\;(52.52\~94.06\%)$ in 1 m layer, $35.46\%\;(4.00\~73.64\%)$ in 5m layer, $18.71\%\;(0.24\~54.23\%)$ in 10m layer and $7.00\%\;(0.007\~27.58\%)$in 20m layer. The rate of light penetration at the transparency layer with reference to the surface light intensity was shown as $13.02\%\;(0.42\~34.78\%)$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.19 no.3
• /
• pp.234-240
• /
• 1986

Optical properties of sea vater were studied in Tokyo Bay, Japan, based on the data obtained from six oceanographic station in April, 1985. The observation of surface and underwater irradiances of sea water for eight kinds of wavelength (378, 422, 481, 513, 570, 621, 653, and 677 mm) of sun light was conducted using the underwater irradiameter (Isigawa ${\sharp}SR-8$). The mean attenuation coefficient of the sea water appeared to be 0.335($0.081{\sim}0.862$) and the attenuation coefficient of the sea water for each wavelength appeared as 0.268 for 378nm, 0.354 for 422nm, 0.274 for 481nm, 0.256 for 513nm, 0.284 for 570nm, 0.356 for 621nm, 0.425 for 653nm, and 0.464 for 677nm. The transparency was 5.0m ($2.5{\sim}6.5m$), water color was 10.2 ($8{\sim}14.0$) in the study area and the sun altitude was $53.62^{\circ}$ ($38.54^{\circ}{\sim}66.23^{\circ}$). The relationship between attenuation coefficient (K) and transparency (D) was K= 2.22/D ($1.30/D{\sim}3.54/D$). The rates of light penetration for eight kinds of wavelength (378, 422, 481, 513, 570, 621, 653, and 677 nm) were computed with reference to the surface light intensity each. The mean rates of light penetration in proportion to depths were $62.72\%$ ($42.23{\sim}78.43\%$) in 1 m layer, $11.91\%$ ($1.34{\sim}29.67\%$) in 5m layer, $2.64\%$ ($0.023{\sim}8.80\%$) in 10m layer, and $0.50\%$ ($0.02{\sim}3.99\%$) in 20 m layer. The rate of light penetration at the transparency layer with reference to the surface light intensity was shown as $12.51\%$ ($2.91{\sim}27.25\%$).