• Ocean Systems Engineering
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• v.10 no.2
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• pp.201-226
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• 2020

A systematic numerical comparative study of the performance of semicircular and rectangular submerged breakwaters interacting with solitary waves is the basis of this paper. To accomplish this task, Nwogu's extended Boussinesq model equations are employed to simulate the interaction of the wave with breakwaters. The finite difference technique has been used to discretize the spatial terms while a fourth-order predictor-corrector method is employed for time discretization in our numerical model. The proposed computational scheme uses a staggered-grid system where the first-order spatial derivatives have been discretized with fourth-order accuracy. For validation purposes, five test cases are considered and numerical results have been successfully compared with the existing analytical and experimental results. The performances of the rectangular and semicircular breakwaters have been examined in terms of the wave reflection, transmission, and dissipation coefficients (RTD coefficients) denoted by K_R, K_T, K_D. The latter coefficient K_D emerges due to the non-energy conserving K_R and K_T. Our computational results and graphical illustrations show that the rectangular breakwater has higher reflection coefficients than semicircular breakwater for a fixed crest height, but as the wave height increases, the two reflection coefficients approach each other. un the other hand, the rectangular breakwater has larger dissipation coefficients compared to that of the semicircular breakwater and the difference between them increases as the height of the crest increases. However, the transmission coefficient for the semicircular breakwater is greater than that of the rectangular breakwater and the difference in their transmission coefficients increases with the crest height. Quantitatively, for rectangular breakwaters the reflection coefficients K_R are 5-15% higher while the diffusion coefficients K_D are 3-23% higher than that for the semicircular breakwaters, respectively. The transmission coefficients K_T for rectangular breakwater shows the better performance up to 2.47% than that for the semicircular breakwaters. Based on our computational results, one may conclude that the rectangular breakwater has a better overall performance than the semicircular breakwater. Although the model equations are non-dissipative, the non-energy conserving transmission and reflection coefficients due to wave-breakwater interactions lead to dissipation type contribution.

• Korean Journal of Human Ecology
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• v.18 no.2
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• pp.523-534
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• 2009

The purposes of this study were to identify brand equity factors influencing on brand preference and to investigate the effects of preference, price acceptability, distribution proximity, and appropriateness on brand performance of domestic and imported cosmetics brands. A total of 300 women aged between 20 and 49 years were surveyed on two domestic brands and two imported brands that were well-known to consumers during the month of September, 2006, in Seoul, Daejeon, Gyeonggi-do, and Chungcheong-do. The data were analyzed with factorial analysis, multiple regression analysis, ANOVA, Cronbach's ${\alpha}$, etc., using the SPSS 12.0. The result of the study included: 1) Four factors of brand equity were identified: brand image, social reputation, quality, and brand awareness. 2) Brand image, quality, appropriateness, and brand performance of the domestic brands were higher than those of the imported brands. But brand awareness of the imported brands was higher than that of the domestic brands. 3) Brand preference of the domestic brands was affected by social reputation, quality, brand image, and brand awareness in order of significance. And brand performance of the domestic brands was affected by brand preference, appropriateness, price acceptability and distribution proximity in order of significance. 4) Brand preference of the imported brands was affected by brand image, social reputation, brand awareness, and quality in order of significance. And brand performance of the imported brands was affected by appropriateness, price acceptability, brand preference, and distribution proximity in order of significance.

• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.175-187
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• 2020

The theories having been developed thus far account for higher-order variation of transverse shear strain through the depth of the beam and satisfy the stress-free boundary conditions on the top and bottom surfaces of the beam. A shear correction factor, therefore, is not required. In this paper, the effect of surface on the axial buckling and free vibration of nanobeams is studied using various refined higher-order shear deformation beam theories. Furthermore, these theories have strong similarities with Euler-Bernoulli beam theory in aspects such as equations of motion, boundary conditions, and expressions of the resultant stress. The equations of motion and boundary conditions were derived from Hamilton's principle. The resultant system of ordinary differential equations was solved analytically. The effects of the nanobeam length-to-thickness ratio, thickness, and modes on the buckling and free vibration of the nanobeams were also investigated. Finally, it was found that the buckling and free vibration behavior of a nanobeam is size-dependent and that surface effects and surface energy produce significant effects by increasing the ratio of surface area to bulk at nano-scale. The results indicated that surface effects influence the buckling and free vibration performance of nanobeams and that increasing the length-to-thickness increases the buckling and free vibration in various higher-order shear deformation beam theories. This study can assist in measuring the mechanical properties of nanobeams accurately and designing nanobeam-based devices and systems.

• Journal of Ship and Ocean Technology
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• v.12 no.2
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• pp.16-31
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• 2008

The lifting-surface programs have been used successfully in practice for the design and global performance prediction of the marine propellers. To predict the pressures on the blade for the strength analysis, the constant panel method has been a good alternative. To meet the need for more accurate information on the pressure near the tip region and the trailing edge of the blade, the higher order panel method (HiPan, hereinafter) based on a B-spline is developed and now available. However, there is an increasing demand to get the highly reliable unsteady behavior of the pressure near the tip region by the HiPan. The ultimate goal of our efforts is to develop the fully unsteady higher order panel code for the propeller. In the present paper, we will show the numerical procedure applicable to unsteady problems of the three dimensional hydrofoil in a sinusoidal gust and heave motions.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.245-250
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• 2002

We study numerically the temporal evolutions of two orthogonally polarized pulses with width less than 100fsec in all-optical phase-shift switches. We analyze the complicated interplay between a soliton pulse and a higher-order soliton pulse, including the self-and the cross-Raman scattering and the walk-off effect. We also investigate the influence of these interactions on switching performance, including pulse-shape, phase-shift distribution, and contrast ratio. In particular we show that an optical fiber with a typical birefringence (Δn : 2.4$\times$10$^{-5}$ ) can be used with good switching performance in such all-optical switches.

• Computers and Concrete
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• v.17 no.5
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• pp.579-596
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• 2016

This paper describes a method of the refined plastic hinge approach in the framework of the higher-order element formulation that can efficaciously evaluate the limit state capacity of a whole reinforced concrete structural system using least number of element(s), whereas the traditional design of a reinforced concrete structure (i.e. AS3600; Eurocode 2) is member-based approach. Hence, in regard to the material nonlinearities, the efficient and economical cross-section analysis is provided to evaluate the element section capacity of non-uniform and arbitrary concrete section subjected to the interaction effects, which is helpful to formulate the refined plastic hinge method. In regard to the geometric nonlinearities, this paper relies on the higher-order element formulation with element load effect. Eventually, the load redistribution can be considered and make full use of the strength reserved owing to the redundancy of an indeterminate structure. And it is particularly true for the performance-based design of a structure under the extreme loads, while the uncertainty of the extreme load is great that the true behaviour of a whole structural system is important for the economical design approach, which is great superiority over the conservative optimal strength of an individual and isolated member based on traditional design (i.e. AS3600; Eurocode 2).

• Journal of the Korean Dietetic Association
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• v.9 no.1
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• pp.22-31
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• 2003

The purposes of this study were to compare performance of HACCP-based sanitary management and sanitation knowledge of employees in some food services (hospitals, elementary school, industry) in Inchon. Therefore, the survey questionnaire consisted of general background, sanitation performance, sanitation knowledge evaluation. The subjects were 370 employees in hospital, elementary school, industrial food service. The statistical analysis of data was completed using SPSS program. The results were summarized as follows: 99.3% of surveyed employees were female. 95.7% of employees were attended sanitation education and 76.8% of them were educated once a month. Employees in school food service showed higher academic career than the other food service employees. The food service employees' performance level was high(4.48). The performance level of school employees was significantly higher compared to other food services(p<0.001). Average score of sanitation knowledge was 16.36/20. The school food service employees' knowledge 17.03 was also higher compared to other food services. There was no significant correlation between sanitary performance and knowledge for total score. But among items of sanitary performance, a personal hygiene and food sanitary was significantly correlated with sanitation knowledge. The results of survey imply that the suitable contents and methods of education and training must be developed. Also, Financial supports to install necessary sanitary facilities are very important in order to raise effectiveness of education.

• Korean Journal of Biological Psychiatry
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• v.4 no.1
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• pp.36-42
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• 1997

Higher cognitive functions refer to the highest level of human intellectual functioning, including concept formation, reasoning, and executive functions. The executive functions can be conceptualized as having four components : volition, planning, purposive action, and effective performance. Because higher cognitive functions represent the most advanced stages of intellectual development, they are often highly susceptible to the effects of brain injuries and mental disorders. The ability to perform effectively within the environment is determined in large part by an individual's adequacy in performing such higher-order functions. Especially executive functions are necessary for appropriate, socially responsible, and effectively self-serving adult conduct. Threfore, an assessment of the psychiatric patient's performance in these areas will provide useful diagnostic information, as well as information concerning social and vocational prognosis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2487-2495
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• 2000

The acoustic characteristics of expansion chamber will be changed with the variation of inlet/outlet location due to the higher order acoustic mode in a high frequency in which the plane wave theory is not available. In this paper, the acoustic performance of reactive type expansion chamber with circular cross-section is analyzed by using the modified mode matching theory. The sensitivity analysis of four-pole parameters with respect to the location of inlet and outlet is also suggested to increase the acoustic performance. The acoustic power transmission coefficient is used as cost function, and the location of inlet and outlet is used as design variables. The steepest descent method and SUMT algorithm are used for optimization technique. Several results showed that the expansion chamber with optimally located inlet/outlet had better acoustic performance than concentric expansion chamber.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.89-99
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• 1998

The purpose of the study was to identify the relationship of the logistics activities with the overall performance among the Korean industries, in order to suggest ways of enhancing the level of effectiveness in logistics management. On the basis of current logistics literature and research data, an analysis had been attempted to provide the study with a theoretical framework, followed by an empirical research that analyzed, among the randomly selected companies, the relations between logistics activities and management policy; logistics activities and logistics environment; logistics environment and the usage of computer software; management policy and the usage of computer software; management policy and performance; logistics environment and performance. Analyses of the data suggested that the companies that lay heavy emphasis on logistics effectiveness showed higher performance; management policies of the companies are influenced by their logistics characteristics; the more strongly is a company oriented logistically, the higher effectiveness in logistics activities it maintains; there is a significant relationship between the logistics environment a company is operated in and the company's reliance on logistically oriented information technologies; there is a close relationship between a company's logistics activities and its business outcome.