• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.163-166
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• 2006

This paper presents numerical results of fluid flows and mixing in a microfluidic device for AC electroosmotic flow (AC-EOF) with coplanar electrodes on top and bottom walls. Differently from previous EOF a channel which attached a couple of coplanar electrodes can be utilized to mix a target liquid with a reagent. In this study we propose a method of controlling fluid flows and mixing enhancement. To obtain the flow and mixing characteristics, numerical computations are performed by using a commercial code, CFX10. It was found that the flow near the coplanar electrodes is of 3-D complex flows and vortices between the other electrodes, and as a consequence the AC-electroosmotic flow on the electrodes plays an important role in mixing the liquid.

• Progress in Superconductivity and Cryogenics
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• v.16 no.3
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• pp.10-14
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• 2014

Due to continuous increase of electric power consumption, couple of resolutions for improving accuracy in power system like line separation are being studied. The increase of the power demand can cause problems such as supply difficulties of the electricity and broadband outages, failure, etc. When a fault occurs in the power system, a fault current also increases. Fault current creates problems like reduction of lifespan and failure on the power system. In order to resolve these problems, the reduction of initial fault current using the characteristics of superconducting element was applied to fault current limiter. We applied the system to high speed fault current limiter. We found that the superconducting element effectively reduced initial fault current and the fault current was limited by changing operation of high speed interrupter.

• Advances in nano research
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• v.10 no.5
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• pp.449-460
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• 2021

Flexoelectricity is an interesting materials' property that is more touchable in small scales. This property beside the sandwich structures placed in the center of scientists' attention due to their extraordinary effects on the mechanical properties. Furthermore, in the passage of decades, more elaborated sandwich structures took into consideration results from using honeycomb core. This kind of structure, inspiring from honeycomb core, provides more stiffness to weight ratio, which plays a crucial role in different industries. In this paper, based on the Love-Kirchhoff's hypothesis, Hamilton's principle, modified couple stress theory and Fourier series analytical method, equations of motion for a sandwich plate containing a honeycomb core integrated by two face-sheets have derived and solved analytically. The equations of both face sheets have derived by flexoelectricity consideration. Moreover, it should be noticed that the whole structure rests on the visco-Pasternak foundation. Conducting current research provided an acceptable and throughout study based on flexoelectricity to address the effect of materials' characteristics, length-scale parameter, aspect, and thickness ratios and boundary conditions on the natural frequency of honeycomb sandwich plates. Also, based on the presented figures and tables, there is a close agreement between previous studies and recent work. Due to the high ratio of strength to weight, current model analyzing is capable of taking into account for different vehicles' manufacturing in a high range of industries.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.209-212
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• 2001

It is known that the mim forming processes show somewhat different phenomena compared with the conventional metal forming processes, namely, the size effect, enhanced friction effect and etc. Such typical phenomena, however, are not predicted by the conventional finite element analysis, which has been an efficient numerical tool to predict the metal forming processes. It is due to the fact that the constitutive relations used does not describe the microstructural characteristics of the materials. In the present investigation, the finite element formulation using the rate-dependent rigid plastic crystal plasticity model of the face-centered cubic materials is conducted to predict the micro mechanical behaviors during the mim forming processes. The finite element analysis, however, provides mesh-dependent solutions for the intragranular deformations. Therefore, the couple stress energy is additionally introduced into the variational principle and formulated within the framework of the rigid plastic finite element method to obtain mesh-independent solutions. Micro deformations of single crystal and bicrystal with various orientations are calculated to show the potential of the developed formulation.

• Steel and Composite Structures
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• v.50 no.4
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• pp.403-418
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• 2024

In this paper, vibration and energy absorption characteristics of a nanostructure which is composed of two embedded porous annular/circular nanoplates coupled by a viscoelastic substrate are investigated. The modified couple stress theory (MCST) and the Gurtin-Murdoch theory are applied to take into account the size and the surface effects, respectively. Furthermore, the structural damping effect is probed by the Kelvin-Voigt model and the mathematical model of the problem is developed by a new hyperbolic higher order shear deformation theory. The differential quadrature method (DQM) is employed to obtain the out-of-phase and in-phase frequencies of the structure in order to predict the dynamic response of it. The acquired results reveal that the vibration and energy absorption of the system depends on some factors such as porosity, surface stress effects, material length scale parameter, damping and spring constants of the viscoelastic foundation as well as geometrical parameters of annular/circular nanoplates. A bird's-eye view of the findings in the research paper offers a comprehensive understanding of the vibrational behavior and energy absorption capabilities of annular/circular porous nanoplates. The multidisciplinary approach and the inclusion of porosity make this study valuable for the development of innovative materials and applications in the field of nanoscience and engineering.

• KIEAE Journal
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• v.11 no.5
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• pp.119-127
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• 2011

The aging population has been increasing in Korea so that it is difficult for people to understand the change of the future society. This study aimed to analyze the characteristics of preliminary retiree's alternative housing preference by providing an accurate information about residential current issues and the seriousness brought by the aging society. It explained the visual information about the aspect of the residential change due to the aging society to 104 preliminary retirees who live in the apartment in Seoul. It surveyed the characteristics of the alternative housing preference following 4 situations of the Old age type(couple/healthy, couple/ill, single/healthy, single/ill). It analyzed the difference of housing preference before and after providing information. The results are as follows: First, a previous apartment is not enough to prepare the aging society and UIBS(unit insertion building system) for the elderly was expected to be a great help to the frail after 2026. Second, the preference of UIBS was increased after providing information of the aging society. Third, in the case of the illness, a big city with medical facilities was preferred not to move in the suburb. Fourth, after providing information, a small size of apartment was preferred but the preferred change of housing ownership was not founded. Last, there was considerable difference before and after providing information under 4 situation of Old age type. These results showed the feasibility of coping with more accurate future society only if a survey should be taken with providing sufficient information about the aging society.

• Journal of Families and Better Life
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• v.33 no.2
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• pp.149-164
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• 2015

In recent years, leisure time has received increasing attention in Korean society. Despite the growing interest, however, there are very few studies that explored shared leisure time, especially among married couples. In this light, the present study examined variations in shared leisure time by demographic characteristics and associations between shared leisure time and quality of marital relationship. We used the third wave of the national data KLoWF (Korean Longitudinal Survey of Women and Families, 9,997 19-64 years old women). The study sample included 5,965 married women with no prior history of divorce. Results showed that Korean wives reported very little shared leisure time with their husbands. Given that the mean of the shared leisure time reported by employed women was significantly lower than that of the un-employed, we speculated that the time constraint may be one of the major barriers to having leisure time with one's spouse among Korean married couples. Married women in their 30's had the most frequent couple leisure time. The younger wives in their 20s had more cultural leisure time with their husbands, but sharing outdoor leisure time was not related to their age. The higher level of education for women was associated with greater shared active leisure time. However, visiting a husband's family often took place regardless of the wives' education level. After controlling for age, years of education, job status and annual family income, shared active leisure time (i.e., cultural activity and exercise) was positively related to marital satisfaction. Visiting one's own family, however, was not considered a leisure activity for Korean wives. Rather, frequent family visits were related to lower marital satisfaction. Findings shed light on how leisure life of married women with spouses are intertwined with not only their socioeconomic status and but also marital relationship in culturally unique ways.

• Journal of Families and Better Life
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• v.35 no.1
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• pp.17-29
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• 2017

The purpose of this study was to identify the needs of marriage education programs for multicultural couples based on their socio-demographic characteristics. A total of 816 multicultural families (247 Korean husbands and 569 foreign wives) were recruited through 99 Multicultural Family Support Centers across Korea. Descriptive statistics and multiple regressions were conducted. The program needs that were relatively higher than other areas included the need to develop education on "understanding the culture and language of partner," "increased intimacy of the couple," "multicultural awareness," and "set goals for life." We also found that each participant's gender, foreign wife's country of origin, participant's education level, and marriage duration were significantly related to the needs of marriage education programs. These findings suggest that family life education for multicultural couples should be based on the characteristics of the program participants such as socio-demographic characteristics and family life cycle instead of providing a universal program for all multicultural couples.

• The Korean Journal of Community Living Science
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• v.27 no.spc
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• pp.557-571
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• 2016

This study examined the effects of the actor and partner according to the activity immersion conflict perceived by rural multicultural couples in terms of the self-esteem and happiness using Actor-Partner Interdependence Model (APIM). For this purpose, the data of 482 persons from 241 husband-immigrant women dyads were analyzed. As results of the analysis, only the effect of the actor among the actor and partner effect according to the activity immersion conflict affected the self-esteem significantly in both husband and immigrant women. Conflict, namely the actor and partner effect, affected the happiness in both the husband and immigrant women significantly. Second, the difference in the actor conflict level on activity immersion perceived by the couple according to the women's native country was significant in both husband and immigrant women. The level of actor conflict was highest in Vietnamese husbands and the Philippine women. On the other hand, the difference in the partner conflict level on the activity immersion according to the women's native country was significant only in the women, and the level of Vietnamese women was highest. Therefore, the characteristics in the level of actor and partner conflict on activity immersion was caused by the difference in the number of activity organizations participating between the husband and women. Based on the results, this study suggests some measures to reduce the conflict of couples through activity. In addition, some plans for a follow-up study using APIM are suggested.

• Journal of Agricultural Extension & Community Development
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• v.15 no.1
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• pp.145-175
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• 2008

This study has been carried out in order to examine the characteristics and rationales of the rural development policies of the President Roh Moo-Hyun's 'Participatory Government. The study is summarized into two different directions: characterization and rationalization. Characteristics of the government's rural development policies during the President Roh Moo-Hyun's 'Participatory Government (2003-2008) were three folds. First, the government has been more concerned with rural income level problems than those of living-environment standards. Second, the effect of the government's rural development policies has depended heavily upon both 'green tourism' and 'regional renovation'. Third, it has emphasized the applications of bottom-up approach particularly. This study found out a couple of problems about the rationales of the recent rural development policies; First, the developmental potentials and effects of policy measures which designate the rural green tourism, the regional renovation, and the bottom-up approach etc. were all over-estimated. Second, the structure of recent rural development policies was not vivid enough. Policy targets and measures have been proposed very vaguely; therefore, they have caused difficulties in identifying the actual feasibility and appropriateness of the rural development policies.