• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.5
• /
• pp.717-724
• /
• 2010

The initial trajectory of a spheroid configuration bobbin for precision guidance has been investigated by analyzing its aerodynamic load and six-degree-of-freedom motion. The effects of changes in the spheroidal head configuration, flow angle and lateral center-of-gravity offset are numerically studied using the commercial software "FLUENT". A wind tunnel test is also conducted to validate the numerical scheme and to examine effect of the Reynolds number on the flow around the bobbin. It is shown that the size of the separation bubble formed on the surface decreases significantly when the Reynolds number is varied between 110,000 and 140,000. At a zero flow angle, an oblate spheroidal head shows relatively moderate rotation while a prolate spheroidal head shows rapid rotation. The bobbin with a spherical head shape has little effect on the flow direction; however, the oblate bobbin is sensitive to the flow angle. The roll motion of the bobbin is greatly influenced by the lateral center-of-gravity offset and maximum dispersion is observed at half of the radius.

• Proceedings of the KOR-KST Conference
• /
• 2000.02a
• /
• pp.25-47
• /
• 2000

In route guidance systems fastest-path routing has typically been adopted because of its simplicity. However, empirical studies on route choice behavior have shown that drivers use numerous criteria in choosing a route. The objective of this study is to develop computationally efficient algorithms for identifying a manageable subset of the nondominated (i.e. Pareto optimal) paths for real-time vehicle routing which reflect the drivers' preferences and route choice behaviors. We propose two pruning algorithms that reduce the search area based on a context-dependent linear utility function and thus reduce the computation time. The basic notion of the proposed approach is that ⅰ) enumerating all nondominated paths is computationally too expensive, ⅱ) obtaining a stable mathematical representation of the drivers' utility function is theoretically difficult and impractical, and ⅲ) obtaining optimal path given a nonlinear utility function is a NP-hard problem. Consequently, a heuristic two-stage strategy which identifies multiple routes and then select the near-optimal path may be effective and practical. As the first stage, we utilize the relaxation based pruning technique based on an entropy model to recognize and discard most of the nondominated paths that do not reflect the drivers' preference and/or the context-dependency of the preference. In addition, to make sure that paths identified are dissimilar in terms of links used, the number of shared links between routes is limited. We test the proposed algorithms in a large real-life traffic network and show that the algorithms reduce CPU time significantly compared with conventional multi-criteria shortest path algorithms while the attributes of the routes identified reflect drivers' preferences and generic route choice behaviors well.

• Journal of Fashion Business
• /
• v.26 no.6
• /
• pp.82-93
• /
• 2022

Sustainability is a significant change that fashion industry has undergone. Marketers and brands are looking for guidance in green advertising to most effectively motivate consumers to purchase sustainable fashion products. This study aims to reveal environmental and cultural sustainability claims on message credibility and purchase intention regarding product trendiness. We performed mediation and moderation analyses, using a 2 (sustainability message: environmental and cultural) × 2 (product design: classic vs. trendy) between-subjects experimental design. The PROCESS MACRO was used for the analysis. Results indicate that environmental claim must appear credible to consumers to motivate them to purchase a product. On the other hand, cultural claim, with and without credibility, affected consumer's purchase intention. Moreover, cultural claim and trendy design together influenced message credibility and purchase intention, showing a moderated mediation effect. The study indicates that brands should broaden their perspective regarding sustainability by considering cultural factors when providing sustainability claims. Environmental claim should be clear and transparent to avoid green skepticism. Also, it is important to focus on product's design aspect: making trendy designs. It is difficult to change consumer behavior based only on sustainability value. Thus, brands must coney their consideration of design trends. Theoretical and managerial implications also are discussed.

• Journal of muscle and joint health
• /
• v.16 no.2
• /
• pp.154-164
• /
• 2009

Purpose: This study was conducted to evaluate the effects of an osteoporosis prevention health education on know ledge, health beliefs, self-efficacy and preventive health behaviors of women in an urban area. Methods: A one- group pre-test-post-test design was conducted to identify the effects of an osteoporosis prevention health education. The study was conducted between April and November 2008, and recruited 98 women in Seoul. All participants completed the pretest and posttest measures with self-administered questionaire: Osteoporosis Knowledge Test, Osteoporosis Health Belief Scale, Osteoporosis Self-Efficacy Scale and Osteoporosis Preventive Health Behaviors Survey. Results: The result of the paired t-test revealed statistically significant difference in the perceived susceptibility and perceived benefits of osteoporosis and osteoporosis preventive behaviors between pretest and posttest measures. However, the difference in knowledge and self-efficacy between the pretest and posttest measures was not statistically significant. Conclusions: These finding indicate the need for further health education to increase osteoporosis knowledge, health beliefs, self-efficacy and osteoporosis preventive health behaviors and provide guidance for developing effective osteoporosis prevention health education strategies.

• Journal of Research and Publication Ethics
• /
• v.4 no.1
• /
• pp.9-14
• /
• 2023

Purpose: Adequate public input and participation in environmental health research must be provided to ensure accurate results from studies involving human exposure to potentially hazardous substances. By addressing these ethical issues associated with environmental health research, this study can help reduce risks for individuals participating in studies and whole communities affected by their impactful findings. Research design, data and methodology: The current research should have followed the rule of qualitative textual research, searching and exploring the adequate prior resources such as books and peer-reviewed journal articles so that the current author could screen proper previous works which are acceptable for the content analysis. Results: The current research has figured out four ethical issues to improve environmental health study as follows: (1) Lack of Guidance for Collecting and Utilizing Data Ethically, (2) Insufficient Consideration Is Given to Vulnerable Populations When Conducting Studies, (3) Unclear Standards Exist for Protecting the Privacy Of Participant's Personal Information, and (4) Conducting Socially and Religiously Acceptable Research in Various Communities. Conclusions: This research concludes that future researchers should consider implementing anonymization techniques where possible so that findings are still accessible, but the risk posed by disclosing identifying information remains minimized during the analysis/publication stages.

• Asia Marketing Journal
• /
• v.11 no.2
• /
• pp.173-192
• /
• 2009

As video games gain popularity and become a normal part of home entertainment, concern about youth access to inappropriate games continues to grow. Some people have claimed that violent video games influence children's aggressive behavior and that violent video games have some responsibility for violence in the school. In response to people's concerns, the video game industry created a video game rating system in 1995 to help parents decide which video games are appropriate for their children. This study investigated whether parents were aware of the video game rating system and how often they have used it when selecting video games for their children. This study attempted to find relationships among parents' attitudes toward video games, their guidance styles for their children's video game play, and their use of the video game rating system. This study found that most parents have used the video game ratings very frequently when they select video games for their children. But many parents still don't understand the video game rating system. This study showed that parents who had more negative attitudes or less positive attitudes toward video games were more likely to impose restrictions on their children's video game play and to use the video game rating system as a means to restrict their children's access to violent video games.

• Journal of the Korean Society of Systems Engineering
• /
• v.19 no.2
• /
• pp.46-58
• /
• 2023

Deterministic safety analysis is a crucial part of safety assessment, particularly when it comes to demonstrating the safety of nuclear power plant designs. The traditional approach to deterministic safety analysis models is to model the nuclear core using point kinetics. However, this simplified approach does not fully reflect the real core behavior with proper moderator and fuel reactivity feedbacks during the transient. The use of Multi-Physics approach allows more precise simulation reflecting the inherent three-dimensionality (3D) of the problem by representing the detailed 3D core, with instantaneous updates of feedback mechanisms due to changes of important reactivity parameters like fuel temperature coefficient (FTC) and moderator temperature coefficient (MTC). This paper addresses a CEA ejection accident at hot full power (HFP), in which the underlying strong and un-symmetric feedback between thermal-hydraulics and reactor kinetics exist. For this purpose, a multi-physics analysis tool has been selected with the nodal kinetics code, 3DKIN, implicitly coupled to the thermal-hydraulic code, RELAP5, for real-time communication and data exchange. This coupled approach enables high fidelity three-dimensional simulation and is therefore especially relevant to reactivity initiated accident (RIA) scenarios and power distribution anomalies with strong feedback mechanisms and/or un-symmetrical characteristics as in the CEA ejection accident. The Systems Engineering approach is employed to provide guidance in developing the work in a systematic and efficient fashion.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.30 no.1
• /
• pp.39-48
• /
• 2024

Purpose: This study aimed to examine nurses' healthy behaviors during the coronavirus disease 2019 (COVID-19) pandemic and related factors. Methods: A cross-sectional study was adapted, and data were collected from 300 hospital nurses between August and November 2021. The nurses' characteristics, healthy behaviors, COVID-19 stress levels, health self-efficacy, and nursing professional pride were self-reported using structured questionnaires. Multivariable linear regressions were conducted to identify factors related to nurses' healthy behaviors. Results: Healthy lifestyle was the lowest among the subscales of healthy behaviors. Nurses' healthy behaviors were related to age (B=0.15, p=.021), COVID-19 stress level (B=-0.08, p=.007), nursing professional pride (B=0.19, p<.001), and health self-efficacy (B=0.38, p<.001). Conclusion: To enhance nurses' healthy lifestyles during the pandemic, organizational support is needed, such as ensuring facilities for rest or physical activities accessible from the hospital and supplying healthy food in hospitals. Younger nurses, nurses with high levels of COVID-19 stress, and nurses with lower health self-efficacy may benefit from hospital organizations that provide more support and guidance in promoting health behaviors. Furthermore, hospital organizations should promote professional pride by empowering nurses' efforts and reinforcing their values.

• Steel and Composite Structures
• /
• v.50 no.2
• /
• pp.149-158
• /
• 2024

Considering that different boundary conditions can have an important impact on structural vibration characteristics. In this paper, the nonlinear forced vibration behavior of functionally graded material (FGM) doubly curved shells with initial geometric imperfections under different boundary conditions is studied. Considering initial geometric imperfections and von Karman geometric nonlinearity, the nonlinear governing equations of FGM doubly curved shells are derived using Reissner's first order shear deformation (FOSD) theory. Three different boundary conditions of four edges simply supported (SSSS), four edges clamped (CCCC), clamped-clamped-simply-simply (CCSS) were studied, and a system of nonlinear ordinary differential equations was obtained with the help of Galerkin principle. The nonlinear forced vibration response of the FGM doubly curved shell is obtained by using the modified Lindstedt Poincare (MLP) method. The accuracy of this method was verified by comparing it with published literature. Finally, the effects of curvature ratio, power law index, void coefficient, prestress, and initial geometric imperfections on the resonance of FGM doubly curved shells under different boundary conditions are fully discussed. The relevant research results can provide certain guidance for the design and application of doubly curved shell.

• Journal of Korean society of Dental Hygiene
• /
• v.23 no.6
• /
• pp.529-536
• /
• 2023

Objectives: This study aimed to determine the relationship between hours of smartphone use and oral disease symptoms in Korean adolescents. Methods: In this study, data from the 2022 Youth Health Behavior Online Survey were used. The final analysis was conducted on students who responded that they have used a smartphone (N=50,375). Chi-squared test and multivariate logistic regression analysis were used to analyze the relationship between oral disease symptoms and smartphone use time (p<0.05). Results: Consequent to examining the effect of smartphone use on oral disease symptoms, it was found that oral symptoms, such as pain during chewing and tingling throbbing, increased as smartphones were used for >4 h (p<0.05). Additionally, oral symptoms, such as gingivalgia bleeding and bad breath, appeared to increase as smartphones were used for >6 h (p<0.05). However, using smartphones for <0-2 h or 2-4 h had no effect on oral disease symptoms. Conclusions: In adolescents, oral disease symptoms increased significantly with increasing hours of smartphone use. Therefore, adolescents should be guided so that they use smartphones for <2 h or >4 h. Moreover, guidance on forming the habit of tooth brushing after eating food should be provided to prevent oral disease symptoms.