• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.22 no.1
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• pp.29-62
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• 2018

We investigate a class of HIV infection models with two kinds of target cells: $CD4^+$ T cells and macrophages. We incorporate three distributed time delays into the models. Moreover, we consider the effect of humoral immunity on the dynamical behavior of the HIV. The viruses are produced from four types of infected cells: short-lived infected $CD4^+$T cells, long-lived chronically infected $CD4^+$T cells, short-lived infected macrophages and long-lived chronically infected macrophages. The drug efficacy is assumed to be different for the two types of target cells. The HIV-target incidence rate is given by bilinear and saturation functional response while, for the third model, both HIV-target incidence rate and neutralization rate of viruses are given by nonlinear general functions. We show that the solutions of the proposed models are nonnegative and ultimately bounded. We derive two threshold parameters which fully determine the positivity and stability of the three steady states of the models. Using Lyapunov functionals, we established the global stability of the steady states of the models. The theoretical results are confirmed by numerical simulations.

• Journal of Powder Materials
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• v.21 no.2
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• pp.137-141
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• 2014

In this study, we report the sintering behavior and properties of a $Ge_2Sb_2Te_5$ alloy powders for use as a sputtering target by spark plasma sintering. The effect of various sintering parameters, such as pressure, temperature and time, on the density and hardness of the target has been investigated in detail. Structural characterization was performed by scanning electron microscopy and X-ray diffraction. Hardness and thermal properties were measured by differential scanning calorimetry and micro-vickers hardness tester. The density and hardness of the sintered $Ge_2Sb_2Te_5$ materials were 5.8976~6.3687 $g/cm^3$ and 32~75 Hv, respectively.

• Journal of the Korean Society of Costume
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• v.62 no.3
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• pp.17-28
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• 2012

The purpose of this study was to investigate elderly women's body image and clothing behavior. Data were collected from 305 elderly women living in Gyeongnam province from May and June of 2011. Statistical methods including frequency analysis, factor analysis, F-test, t-test, Duncan test, Cronbach's ${\alpha}$, correlation analysis and multiple regression were used for this study. The results of this study were as follows.: The body image was composed of two factors, 'physical attractiveness and interest in appearance', and 'concern about weight'. The clothing behavior was composed of the following five factors: 'social importance', 'conformity' 'individuality' 'economic efficiency' and 'clothing fashion interest'. The body image and clothing behavior according to the elderly women' demographic showed many differences. Elderly women's body image influenced their clothing behavior. These study results are highly expected to be used as valuable sources in fashion marketing plans for industries that target elderly women.

• Journal of Fashion Business
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• v.1 no.4
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• pp.67-78
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• 1997

Fashion store patronage behavior can be observed when consumer's desires and expectations are fulfilled. Thus, in order to achieve successful business in sales, a retailer must continually analyze why target consumers choose particular stores and patronize them. This study identified the relevant factors of the patronage behavior of female college students residing in Seoul. Thus, this study can achieve Its goal of enabling retailers to predict shopping orientations and emphasis on store attributes, so that help retailer to establish new positions of their shops to differentiate them from others and, also, to reposition existing stores. The aims of this study were as follows; First, identify the classification of stores that female college students in Seoul patronize. Second, classify the female students' shopping orientations, emphasizing store attributes, and identify relationships between them and fashion store patronage behavior. Relationships between the factors of shopping orientations and store attributes, and patronage behavior were identified by use of Tukey's test, Duncan test, and ANOVA. As a result, it showed significant differences among patronage groups according to nearly every factor of shopping orientations and store attributes. As based on the results, this study is expected to assist that retailers can establish effective marketing strategies in order to make continuously consumers' partronage behavior of a store.

• Korean Journal of Health Education and Promotion
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• v.32 no.5
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• pp.1-15
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• 2015

Objectives: This study aimed to identify general characteristics of health status and health behavior of adolescents in accordance with their purposes with internet. Methods: Based on Adolescent Health Behavior Online Survey (KYRBS) in 2014, a total of 57,333 adolescents who had used internet were examined in this study. Results: Users for non-academic purposes were associated with male, low grades, low education level of parents, low income level, being apart from parents, being without any consulting partners, being with one parent families, low perceived health status, the experience suicidal ideation and negative health behavior such as alcohol and tobacco. In particular, these trends were appeared strongly by internet users for the purpose of the non-academic purposes. Male among high grades is shown to be mostly Academic internet users and they were more likely to have problems with some health behaviors such as exercise frequency and smoking. Conclusions: Target population should be internet users for only non-academic purposes to prevent internet addiction of adolescents. Internet addiction prevention program should be provided in terms of mental health and problematic behavior. Additionally, health behavior of internet over user for only academic purposes should be concerned.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.4
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• pp.109-120
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• 2022

This study has incorporated the mechanics-dynamics-emotions (MDE) and two behavioral learning paths to investigate the customers' co-creation behavior in Taiwan. The intuitive path begins with a gamification design that reflects the customers' proactive and innovative behavior; the cognitive path begins with persuasion knowledge remarks based on rational and reactive reasoning. These two paths conclude what forms user co-creation. The study collects data of 505 active social media users in Taiwan and employs structural equation modeling. The empirical findings demonstrate persuasive knowledge and gamification design are significantly associated with self-reference, and in turn, positively associated with co-creation. It indicates that cognitive behavior plays the main role in forming co-creation. Participants are more drawn to co-creation behaviors by the marketing contents that prompt reactive behaviors than proactive ones. Therefore, marketing managers can use appropriate stimuli to enhance co-creation behavior. Companies can design activities related to users, and more accessible for reactive, instead of proactive behavior, i.e., asking for their initiatives. It also suggests that companies' marketing campaigns should involve key opinion leaders matching the product image and the target audience's preferences. The novelty of this study is to introduce a novel augmented MDE framework to extend the "dynamics" into the incubation and implementation stage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.2
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• pp.165-170
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• 2009

Recently, wide spread distribution of the giant jellyfish, Nemopilema nomurai, has occurred in the East China Sea. This increased distribution has caused serious problems in inshore and offshore fisheries in Korea and Japan. As a result, it is necessary to evaluate the damage caused to the fisheries by jellyfish. Accordingly, several hydroacoustic studies have been conducted to estimate the target strength (TS) of the giant jellyfish. However, the effects of fluctuation in the acoustic scattering characteristics on swimming patterns have not yet been elucidated. Therefore, in this study, we theoretically estimated the effects of changes in the acoustic scattering pattern on the swimming behavior of jellyfish using the Distorted Wave Born Approximation (DWBA) model. The results confirmed that acoustic scattering of jellyfish results in a significant change in their swimming pattern. Specifically, our theoretical estimation indicated that the TS of giant jellyfish (d=40 cm) fluctuated until 8.5 dB at 38 kHz, 13.8 dB at 70 kHz, and 15.1 dB at 120 kHz based on changes in their swimming patterns.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.1
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• pp.51-59
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• 2017

PURPOSE: This study compared cognitive task-directed functional motor control ability for reaching and kicking movements in younger and older adults. METHODS: Subjects were divided into two groups of younger and older adults, with 13 subjects in each group. Subjects were required to perform a dual task combining a functional movement and cognitive component. The task consisted of reaching and kicking movements. Participants performed indicated movements when a target appeared on a monitor. The target randomly appeared on the monitor every 10 seconds. The total performance time (TPT), joint angular velocity (JAV), and muscle activation time were used to evaluate motor control ability. RESULTS: There were significant differences in all evaluation factors in a comparison of younger and older adults (p<.05). TPT was significantly shorter in older adults, and JAV and muscle activation time were significantly slower than that in the younger adult group. Although the results for older adults were within the normal range for functional assessment, their motor control abilities were significantly worse for cognitive tasks compared with those of younger adults. CONCLUSION: The results of this study indicated that a motor control assessment tool using a cognitive task would be helpful in assessment of motor control ability in healthy older adults.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.1
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• pp.77-83
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• 2003

Autonomous mobile robots based on the Web have been already used in public places such as museums. There are many kinds of problems to be solved because of the limitation of Web and the dynamically changing environment. We present a methodology for intelligent mobile robot that demonstrates a certain degree of autonomy in navigation applications. In this paper, we focus on a mobile robot navigator equipped with neuro-fuzzy controller which perceives the environment, make decisions, and take actions. The neuro-fuzzy controller equipped with collision avoidance behavior and target trace behavior enables the mobile robot to navigate in dynamic environment from the start location to goal location. Most telerobotics system workable on the Web have used standard Internet techniques such as HTTP, CGI and Scripting languages. However, for mobile robot navigations, these tools have significant limitations. In our study, C# and ASP.NET are used for both the client and the server side programs because of their interactivity and quick responsibility. Two kinds of simulations are performed to verify our proposed method. Our approach is verified through computer simulations of collision avoidance and target trace.

• Journal of Korean Association for Spatial Structures
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• v.18 no.4
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• pp.105-111
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• 2018

In this study, the seismic performance and behavior characteristics of the upper truss structure of the large stadium are analyzed by nonlinear dynamic analysis. In the nonlinear dynamic analysis, the earthquake records were generated by site response analysis to simulate the nonlinear behavior of the relevant soil condition where the structure is located. Nonlinear dynamic analysis was performed using Perform-3D and the nonlinear properties of the substructure and the superstructure were determined in accordance with KISTEC guideline. According to the analysis results, excessive deformation occurred in the upper truss element, and plastic hinges exceeded the target performance in some members. Buckling-restrained brace is used for seismic retrofit of stadium structures and the analysis results shows the interstory drift satisfies the target performance level with dissipating the seismic energy efficiently.