• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.25 no.2
• /
• pp.54-65
• /
• 2021

In this study, a two-dimensional thermoelastic problem under hyperbolic heat conduction theory with an internal heat source is considered. The general solution for the temperature field, stress components and displacement field are obtained using the reduced differential transform method. The stress and displacement components are obtained using the thermal stress function in the reduced differential transform domain. All the solutions are obtained in the form of power series. The special case with a time-dependent laser heat source has been considered. The problem is considered for homogeneous material with finite rectangular cross-section heated with a non-Gaussian temporal profile. The effect of the heat source on all the characteristics of a material is discussed numerically and graphically for magnesium material taking a pulse duration of 0.2 ps. This study provides a powerful tool for finding the solution to the thermoelastic problem with less computational work as compared to other methods. The result obtained in the study may be useful for the investigation of thermal characteristics in engineering and industrial applications.

• East Asian Journal of Business Economics (EAJBE)
• /
• v.9 no.1
• /
• pp.1-16
• /
• 2021

Purpose - This study aims to analyze 7-Eleven's specific competitive advantage strategy according to changes in the Japanese convenience store industry by selecting 7-Eleven, a leading company in the Japanese convenience store industry, as a representative case study. Research design, data, and methodology - Due to the current COVID-19 situation, fact-finding such as interviews with key managers through visiting surveys was not possible, so this case study was carried out based on the literature such as official and unofficial data collected from the companies through e-mail and articles that have been published outside. Result - As a result of the analysis, the researcher found that five competing strategy factors, such as dominant strategy, innovative logistics system strategy, information system development strategy, joint product development strategy, and direct communication strategy have closely maintained the mutual relation to form a combined strategy focusing on the franchise development strategy. Conclusion - The competitive advantage of 7-Eleven is thought to have secured its competitive advantage by combining the five competitive strategies complementarily for rapid response to change, cost advantage, and differentiated advantage. The management implications specified in this study can be considered a reference for establishing a competitive strategy for sustainable growth of the convenience store industry in the fierce competition and saturated market environment of Korean convenience stores.

• Journal of East-West Nursing Research
• /
• v.16 no.2
• /
• pp.122-130
• /
• 2010

Purpose: This study was aimed at finding factors influencing cognitive impairment which is one of the typical symptoms among the demented elderly. Methods: The number of subjects was 417 elderly residents aged over 65 yr in a community. A cognitive function and a depression level were measured using the Korean Version of Mini-Mental State Examination (MMSE-K) and the Korean Form of Geriatric Depression Scale (KGDS). Alcohol abuse was measured using the CAGE instrument. Chi-square test and Logistic regression analysis were conducted to identify factors affecting cognitive impairment. Results: The prevalence rates of cognitive impairment of the sample was 43.5%. Sex, age, educational level, perceived health and alcohol abuse were strong factors influencing cognitive impairment. However, the effects of smoking, living alone, depression, family history in dementia and stroke were not strong. Conclusion: Risk for cognitive impairment were increased by being female and older than 70 yr, having low education, perceiving health as poor, and drinking alcohol abusively. Therefore, a reinforcement system, continuous research and the development of proper programs should be preformed in order to prevent cognitive impairment.

• Nuclear Engineering and Technology
• /
• v.55 no.4
• /
• pp.1324-1331
• /
• 2023

In the present work, we carried out a molecular dynamics study of the kinetic properties of the FLiNaK molten salt, as well as a detailed study of the structure of this salt melt. The high value of the self-diffusion coefficient of fluorine ions is due to the large number of Coulomb repulsions between the most numerous negative ions. The calculated values of shear viscosity are in good agreement with the experimental data, as well as with the reference data obtained on the basis of finding the most reliable data. The total and partial functions of the radial distribution are calculated. According to the statistical analysis, fluorine ions have the greatest numerical diversity in the environment of similar ions, and sodium ions with the lowest representation in FLiNaK, have the least such diversity. For the subsystem of fluorine ions, the rotational symmetry of the fifth order is the most pronounced. Some of the fluorine ions form linear chains consisting of three atoms, which are not formed for positive ions. The results of the work give an understanding of the behavior molten FLiNaK under operating conditions in a molten salt reactor and will find application in future studies of this molten salt.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.12
• /
• pp.24-29
• /
• 1997

Recently, Genetic Algorithm(GA), which is a stochastic direct search strategy that mimics the process of genetic evolution, is widely adapted into a search procedure for structural optimization. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA is very simple in their algorithms and there is no need of continuity of functions(or functionals) any more in GA. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher porbability of convergence to global optimum compared to traditional techniques which take one-point search method. The methods consist of three genetics opera- tions named selection, crossover and mutation. In this study, a method of finding the omtimum size and topology of drilling machine is proposed by using the GA, For rapid converge to optimum, elitist survival model,roulette wheel selection with limited candidates, and multi-point shuffle cross-over method are adapted. And pseudo object function, which is the combined form of object function and penalty function, is used to include constraints into fitness function. GA shows good results of weight reducing effect and convergency in optimal design of drilling machine.

• The Research Journal of the Costume Culture
• /
• v.32 no.1
• /
• pp.17-37
• /
• 2024

This study examines the rise of the Body Positive Movement on TikTok and its role as a form of online content activism influencing the fashion design and industry. Through a combination of literature review and case study methodology, the study explores the expression techniques and thematic types of Body Positive Movement on TikTok. Reviews of literature, previous studies, online articles, fashion journals, and relevant search terms on TikTok informed a definition of Body Positive Movement and an analysis of its formation and rise. The research findings confirm the impact TikTok content on Body Positive Movement has on the fashion industry in addressing external factors (i.e., 'Appearance', 'Race', 'Aging', 'Physical Disability') and intrinsic factors (i.e., 'Acceptance of Diversity', 'Self-Esteem', 'Rejection of Stereotypes', 'Appropriate Representation', 'Information Provision'). The key external factor , 'Appearance', includes subcategories such as 'Body Shape', 'Body Hair', 'Skin', and 'Facial Features'. TikTok content creators on fashion creatively combine music, emojis, and visual storytelling to exhibit positive self-perception concerning these factors. A significant finding of the study is that short clips predominantly manifesting external factors differentiate into informative or enlightening videos associated with intrinsic factors. The study underscores Body Positive Movement's important influence on the fashion industry from design to presentation.

• Journal of the Korean Mathematical Society
• /
• v.61 no.5
• /
• pp.975-995
• /
• 2024

In this paper, we utilize Nevanlinna theory to study the existence and forms of solutions for quadratic trinomial complex partial differential-difference equations of the form aF² + 2ωFG + bG² = exp(g), where ab ≠ 0, ω ∈ ℂ with ω² ≠ 0, ab and g is a polynomial in ℂⁿ. In order to achieve a comprehensive and thorough analysis, we study the characteristics of solutions in two specific cases: one when ω² ≠ 0, ab and the other when ω = 0. Because polynomials in several complex variables may exhibit periodic behavior, a property that differs from polynomials in single complex variables, our study of finding solutions of equations in ℂⁿ is significant. The main results of the paper improved several known results in ℂⁿ for n ≥ 2. Additionally, the corollaries generalize results of Xu et al. [Rocky Mountain J. Math. 52(6) (2022), 2169-2187] for trinomial equations with arbitrary coefficients in ℂⁿ. Finally, we provide examples that endorse the validity of the conclusions drawn from the main results and their related remarks.

• Tribology and Lubricants
• /
• v.30 no.5
• /
• pp.303-310
• /
• 2014

In order to reduce friction and improve reliability, researchers have applied various surface texturing methods to highly sliding machine elements such as mechanical seals and piston rings. Despite extensive theoretical research on surface texturing, previous numerical results are only applicable to isothermal and iso-viscous conditions. Because the lubricant flow pattern of textured bearing surfaces is much more complicated than that for non-textured bearings, the Navier?Stokes equation is more suitable than the Reynolds equation for the former. This study carries out a thermohydrodynamic (THD) lubrication analysis to investigate the lubrication characteristics of a single micro-dimpled parallel thrust bearing cell. The analysis involves using the continuity, Navier?Stokes, energy, temperature?viscosity relation, and heat conduction equations with the commercial computational fluid dynamics (CFD) code FLUENT. This study discretizes these equations using the finite volume method and solves them using the SIMPLE algorithm. The results include finding the streamlines, pressure and temperature distributions, and variations in the friction force and leakage for various dimple radii and depths. Increasing the dimple radius and decreasing the depth causes a recirculation flow to form because of a strong vortex, and the oil temperature greatly increases compared with the non-textured case. The present numerical scheme and results are applicable to THD analysis of various surface-textured sliding bearings and can lead to further study.

• Journal of Korean Home Economics Education Association
• /
• v.4 no.1
• /
• pp.17-30
• /
• 1992

This study aims at finding a new home economics education with will include male students as its teaching objects, and then providing home economics teachers with useful materials. For this purpose I examined the curriculum of foreign home economics education and analized male and female secondary school students’and their recognition and demand to the home economics education. Investigated persons are male and female students of the first year of 3 sendary schools and their parents in Seoul, who are choosen by menas of random sampling. The items analysis of questionnaires was performed by means of random sampling. The items analysis of questionnaires was performed by means of SPSS. The results are marked with percentage and the significance level is verified by t and X(sup)2 analysis methods. The results obtained from the items analysis are as follows：1 According to the increasing number of female employees, the mechanization of household affaires, and so on, male students and male parents got to realize the necessity of home economics education and the importance of men and women’s cooperation to lead a family life. 2. It is shown that the goal of home economics deucation must be to form a right value point of the family life and family. This fact implies that many examinees regards the home economics education in the moral point of view. 3. In the necessity degree according to each field of the home economics education curriculum, moral and social aspects such as family relationship, home management & economics, human development and bringing up are regarded more important than household affairs and the related technical aspects. 4. In the difference between groups to the necessity degree according to each field of the home economics education curriculum, there are few differences between male and female parents, but there are many differences between male and female students. Male students regards the contents of the home economics education curriculum less necessary than female students. Especially in the field of clothing, residence, human development and bringing up, the difference between male and female students is obvious. 5. The necessity degree of the contents related to environmental pollution, saving of energy and resources, utilizing of computer, etc. is very high.

• Journal of Korean Society of Steel Construction
• /
• v.10 no.1 s.34
• /
• pp.73-83
• /
• 1998

Considering dynamic behaviors according to initial tension forces, geometric nonlinearity and the effect of higher eigen modes to participate in dynamic behaviors increase as initial tension forces decrease, and from phase portrait we can realize that period attractors are produced in many area with complexity. If initial tension forxes increase, difference between linear and nonlinear solutions will decrease and the first eigen mode dominate the dynamic behaviors and observing phase portrait, period attractors appear in certain area regularly. These results may offer meaningful informations to nonlinear dynamic analysis using modal reduction methods such as Lanczos modal analysis. And actually nonlinear dynamic analysis needs very large computational efforts. So, if we determine the number of eigen modes to take part in modal analysis corresponding to initial tension forces we will get more accurate data close to exact nonlinear dynamic solutions.