• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.21 no.1
• /
• pp.1-16
• /
• 2017

The Allen-Cahn equation is solved numerically by operator splitting Fourier spectral methods. The basic idea of the operator splitting method is to decompose the original problem into sub-equations and compose the approximate solution of the original equation using the solutions of the subproblems. The purpose of this paper is to characterize higher order operator splitting schemes and propose several higher order methods. Unlike the first and the second order methods, each of the heat and the free-energy evolution operators has at least one backward evaluation in higher order methods. We investigate the effect of negative time steps on a general form of third order schemes and suggest three third order methods for better stability and accuracy. Two fourth order methods are also presented. The traveling wave solution and a spinodal decomposition problem are used to demonstrate numerical properties and the order of convergence of the proposed methods.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.20
• /
• pp.8571-8576
• /
• 2014

Phytomedicines are believed to have benefits over conventional drugs and are regaining interest in current research. Moringa oleifera is a multi-purpose herbal plant used as human food and an alternative for medicinal purposes worldwide. It has been identified by researchers as a plant with numerous health benefits including nutritional and medicinal advantages. Moringa oleifera contains essential amino acids, carotenoids in leaves, and components with nutraceutical properties, supporting the idea of using this plant as a nutritional supplement or constituent in food preparation. Some nutritional evaluation has been carried out in leaves and stems. An important factor that accounts for the medicinal uses of Moringa oleifera is its very wide range of vital antioxidants, antibiotics and nutrients including vitamins and minerals. Almost all parts from Moringa can be used ad a source for nutrition with other useful values. This mini-review elaborates on details of its health benefits.

• The Journal of Korean Institute for Practical Engineering Education
• /
• v.4 no.2
• /
• pp.1-6
• /
• 2012

This paper introduces a model of practice education for creative problem solving, using five steps on CPS. Learners can get the motivation about development of creative thinking and problem solving skill through the theory of CPS. Furthermore, they can apply problem solving skill to various problem. As a result of the study, the learners could realize the importance of the problem definition and the creative problem solving method. We proposed a guideline about five steps of CPS method and a method about idea evaluation. So, we established the education model about leaners can get the creative problem-solving skill more efficiently.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.27 no.2
• /
• pp.69-79
• /
• 1999

This study identifies the features of landscape elements on the fifteen districts with the idea of land use area and visual quantity of pictures by analyzing the air photo. Therefore, the sensibility of observer is comprehended through simulating the landscape evaluation and the landscape preference with using slide film. The study is divided into three periods to understand the transition of rural landscape as the social and cultural environments have been changed. The first period is the New Community Movement which affected the rapid change of social and cultural environments. The second and third periods are the prior and post time at the rearrangement of administration district in the Tae-Jeon Broad City. The result of this study is explained below part; 1. The transition of rural landscape has been occurred as the land use pattern has been altered. The change of pattern has affected an increase of the natural space and the structure change of agricultural productive space. 2. In the regression analysis, the regression model of landscape preference and land use ratio show; Landscape preference = 3.632 - 11.618 (Residential Area) - 4.227 (Equipped Farm). The explanation variables defined as Residential Area and Equipped Farm, and the relationship of those factors shows negative. Therefore, the increase of other building will make the rural landscape lower and worse.

• International Journal of Automotive Technology
• /
• v.2 no.1
• /
• pp.17-23
• /
• 2001

Measurements of the initial values lead to an inverse and mathematically unprecisely formulated problem. A precise definition of an inverse problem is possible. It is to state a mathematical model of a physical process with clearly defined initial and exit values for the system behind the process. One can grasp the idea of an inverse problem by considering the tire as a copy of the objects of nature in a room with observations. Interpretation of nature is generally a result of an inverse problem. On one hand, the tire may be represented through the sensory organs and the nervous system as well as the experiences of the developer's existing apparatus of the projection of reality. On the other hand, it may be represented by a physical law or a model that can be confirmed or is to be refuted with the help of suitable measurements. During reconstruction of a measuring signal and the identification of a black box that can be assumed to be linear and causal, the tire becomes a first type Volterra integral equation of the convolution type. But measurements of the initial values are always fuzzy, the errors grow and the system behavior can no longer be forecasted. Thus, we have to deal with a chaotic system. This chaos produces fractals in a natural way. These are self-similar geometric structures. This self-similarity is clearly visible in the design.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.15 no.12
• /
• pp.1054-1059
• /
• 2002

A great deal of research has been done in the field of characterization for piezoelectric thin films after the first report on the measurement for the piezoelectric coefficient of thin films in 1990. The main idea of this research is to provide a distinctive solution for the measurement and standardization of both the longitudinal and the transverse piezoelectric d-coefficients, d33 and d31, of ferroelectric thin films. In general, to get these two coefficients of thin films, two different measuring systems are required. Here, we propose the improved method for the evaluation of these two coefficients with single equipment and with the relatively convenient procedure. The two-step loading process of applying the both positive and the negative pressure has been introduced to acquire the piezoelectric coefficients. These results have been calibrated for both the longitudinal and 4he transverse piezoelectric d-coefficients, d33 and 431, of thin films by comparison with the virtual standard created from FEM. In this experiments, we have obtained d33 of 331pC/N and 031 of -92.2pC/N for the PZT thin films.

• Nuclear Engineering and Technology
• /
• v.47 no.3
• /
• pp.351-361
• /
• 2015

External reactor vessel cooling (ERVC) for in-vessel retention (IVR) has been considered one of the most useful strategies to mitigate severe accidents. However, reliability of this common idea is weakened because many studies were focused on critical heat flux whereas there were diverse uncertainties in structural behaviors as well as thermal-hydraulic phenomena. In the present study, several key factors related to molten corium behaviors and thermal characteristics were examined under multi-layered corium formation conditions. Thereafter, systematic finite element analyses and subsequent damage evaluation with varying parameters were performed on a representative reactor pressure vessel (RPV) to figure out the possibility of high temperature induced failures. From the sensitivity analyses, it was proven that the reactor cavity should be flooded up to the top of the metal layer at least for successful accomplishment of the IVR-ERVC strategy. The thermal flux due to corium formation and the relocation time were also identified as crucial parameters. Moreover, three-layered corium formation conditions led to higher maximum von Mises stress values and consequently shorter creep rupture times as well as higher damage factors of the RPV than those obtained from two-layered conditions.

• Journal of the Korean Home Economics Association
• /
• v.31 no.4
• /
• pp.183-191
• /
• 1993

This study was investigated the personal rating reason for preference, and opinion for improvement on the Korean traditional foods. Questionnaire were answered by male and female university students at 8 universities in Seoul and the results are summarized as follows. 1) General trend of subjects showed preference for traditional food in order of nutrition, appearance, taste, economics, and cooking method. While the value of food itself such as nutrition, appearance, taste was rated high, practical side such as economics, and cooking method was not so agreed. Especially female students set as lower value on cooking method. 2) As a reason for rating it low, male and female students answered without distinction that traditional food are laborious and much time is needed for cooking. 3) For the idea of improving traditional food, all students had same opinion that standardized cooking method should be developed for convenient use at home, and secondly, special salestore of traditional food should be promoted. Particularly more male students had the opinion that traditional cooking method should be succeeded to at home than female students. Summarizing some significant findings from the analysis of data, all students prefer traditional food itself relatiovely. But generally they rate it low because traditional food is difficult to cook and there are not so many chances of eating. Therefore, it is regarded that standardized cooking method and promoted special salestore for more chance of eating will activated the interest of young generation, and hence contribute to succession of tradition.

• Journal of Korean Association for Spatial Structures
• /
• v.17 no.1
• /
• pp.49-58
• /
• 2017

The result of the previous work leads to the idea that the inner area of the hyperbolic shell generator should be minimized for the cooling tower with higher first natural frequency. In this study the inner area of the hyperbolic shell generator was graphically established under varying height of the throat and angle of the base lintel. From the graph, several shell geometries were selected and analysed in the aspect of the natural frequency. Three representative towers reinforced differently due to different first natural frequencies were analysed non-linearly and evaluated using a damage indicator based on the change of natural frequencies. The results demonstrated that the damage behaviour of the tower reinforced higher due to a lower first natural frequency was not necessarily advantageous than the others.

• Korean Parent-Child Health Journal
• /
• v.10 no.1
• /
• pp.3-12
• /
• 2007

Purpose: The purpose of this study was to test a KPAAT(Korean Parent As a Teacher Test) and provide a basic data to develop parent education program. Methods: This is a secondary analysis study using 103 preschool mothers who were chosen from 2 kindergarten and child care center located at Kyounki-Do. Results: 1) Subjects' child-rearing attitude was above average at the point of $2.86({\pm}\;.20)$. 2) 16 sub-dimension(response to question, permissive attitude of play, control, control of play, expectation about child, understanding about learning, support of learning, encouragement of thinking, provision of imaginary play opportunities, support of play, encouragement of accomplishment motivation, propriety of child-rearing, affectional support, fixed idea, confidence about education, limitation) and 6 factors(response to question, permission of play, control & limitation, evaluation & support about child, encouragement of academic accomplishment, facilitation of the development of creativity) were above 2.50 except ($2.24{\pm}\;.29$) sub-dimension. 3) There was no significant difference statistically according to subjects' general characteristics. Conclusion: From this study, KPAAT can be utilized later childhood period. And nurses need to help mothers to have sound child rearing attitude.