• Journal of Digital Convergence
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• v.10 no.1
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• pp.185-194
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• 2012

Population aging in Korea is in progress rapidly, though it isn't recognized as a critical situation now. Absolute scale of population will decrease since 2030 and that of 2050 will stay in 2005 levels. But most serious problem is that the core working age group, 25-54 ages will begin to decrease since 2012 because of low fertility and population aging. In these situation of population aging, we will face inevitably great amount of labor force shortages and we should build up policy alternatives for solving these problems. I proposed some policy alternatives. firstly, pronatalism policies including state-supported child-care system for preventing decreases of absolute scale of population. Second, facing up to labor shortages under population aging, I proposed policy alternatives for increasing labor market participation, measured by employmeny rate, of aged (or aging) people including wage-peak system of extending retiring ages and women including lowering opportunity costs of women labor market participation rates, given laboer forces. And to conclude, we should approach to the aging problems by steady state equilibrium ecnomic growth, under inevitable population aging.

• Advances in environmental research
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• v.3 no.1
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• pp.45-69
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• 2014

The groundwater has been a major source of water supply throughout the ages. Around 50% of the rural as well as urban population in the developing countries like India depends on groundwater for drinking. The groundwater is also an important source in the agriculture and industrial sector. In many parts of the world, groundwater resources are under increasing threat from growing demands, wasteful use and contamination. A good planning and management practices are needed to face this challenge. A key to the management of groundwater is the ability to model the movement of fluids and contaminants in the subsurface environment. It is obvious that the contaminant source activities cannot be completely eliminated and perhaps our water bodies will continue to serve as receptors of vast quantities of waste. In such a scenario, the goal of water quality protection efforts must necessarily be the control and management of these sources to ensure that released pollutants will be sufficiently attenuated within the region of interest and the quality of water at points of withdrawal is not impaired. In order to understand the behaviour of contaminant transport through different types of media, several researchers are carrying out experimental investigations through laboratory and field studies. Many of them are working on the analytical and numerical studies to simulate the movement of contaminants in soil and groundwater of the contaminant transport. With the advent of high power computers especially, a numerical modelling has gained popularity and is indeed of particular relevance in this regard. This paper provides the state of the art of contaminant transport and reviews the allied research works carried out through experimental investigation or using the analytical solution and numerical method. The review involves the investigation in respect of both, saturated and unsaturated, porous media.

• Geomechanics and Engineering
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• v.22 no.6
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• pp.541-552
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• 2020

With the increasing tension of current coal resources and the increasing depth of coal mining, the gob-side entry retaining technology has become a preferred coal mining method in underground coal mines. Among them, the technology of the gob-side entry retaining with the high-water filling material can not only improve the recovery rate of coal resources, but also reduce the amount of roadway excavation. In this paper, based on the characteristics of the high-water filling material, the technological process of gob-side entry retaining with the high-water filling material is introduced. The early and late stress states of the filling body formed by the high-water filling materials are analyzed and studied. Taking the 8th floor No.3 working face of Xin'an coal mine as engineering background, the stress and displacement of surrounding rock of roadway with different filling body width are analyzed through the FLAC^3D numerical simulation software. As the filling body width increases, the supporting ability of the filling body increases and the deformation of the surrounding rock decreases. According to the theoretical calculation and numerical simulation of the filling body width, the filling body width is finally determined to be 3.5m. Through the field observation, the deformation of the surrounding rock of the roadway is within the reasonable range. It is concluded that the gob-side entry retaining with the high-water filling material can control the deformation of the surrounding rock, which provides a reference for gob-side entry retaining technology with similar geological conditions.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.130-134
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• 2006

The injection uniformity of the fuel manifold in a liquid rocket engine has been analyzed with dividing plates to improve the cooling performance at the face plate. Three dimensional computational fluid dynamics analysis has been performed to compare the injection uniformity for 5 candidate designs and has been verified to compare with the measured data for the optimal manifold design. For the case I and II, the coolant mass flux increases as the whole working fluid is enforced to flow under the dividing plate. The injection uniformity decreases due to the variation of mass flux at the end of dividing plate and the concentration of mass flow rate at the center of manifold. However case III and IV have uniform injection performance due to reduced mass flux concentration as the coolant can flow along both upper passage and lower passage of the dividing plate. Among the candidate designs, case IV is thought to be the optimal dividing plate with regard to cooling performance and injection uniformity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1664-1670
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• 2015

As journal bearing has a sliding motion between the shaft and bearing with lubricating oil, it produces a hydrodynamic lubrication condition. Journal bearing can receive a large force because it takes a distributed load at the large friction face. As the oil groove or oil hole is made in the journal bearing surface for the journal bearing smoothly working under a hydrodynamic lubrication condition, sufficient lubricating oil is supplied through the clearance of journal bearing. The performance of the journal bearing is changed according to the shapes, sizes and positions of an oil groove. In this paper, the flow rate according to the oil groove shapes (triangle, semicircle and rectangle) among the various oil supply conditions was measured. The shape that discharges the highest flow rate was observed and the groove shape of optimal performance for the journal bearing was determined. The results showed that the flow rate increases with decreasing operating temperature, the influence of temperature on the flow rate decreased with increasing rotational speed, and flow rate in the triangular groove shape was greater than in other shapes.

• International Journal of Highway Engineering
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• v.17 no.6
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• pp.27-32
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• 2015

PURPOSES : It is difficult to estimate tunnel stability because of lack of timely information during tunnel excavation. Tunnel deformability refers to the capacity of rock to strain under applied loads or unloads during tunnel excavation. This study was conducted to analyze a methods of pre-evaluation of stability during tunnel construction using the critical strain concept, which is applied to the results of tunnel settlement data and unconfined compression strength of intact rock or rock mass at the tunnel construction site. METHODS : Based on the critical strain concept, the pre-evaluation of stability of a tunnel was performed in the Daegu region, at a tunnel through andesite and granite rock. The critical strain concept is a method of predicting tunnel behavior from tunnel crown settlement data using the critical strain chart that is obtained from the relationship between strain and the unconfined compression strength of intact rock in a laboratory. RESULTS : In a pre-evaluation of stability of a tunnel, only actually measured crown settlement data is plotted on the lower position of the critical strain chart, to be compared with the total displacement of crown settlement, including precedent settlement and displacement data from before the settlement measurement. However, both cases show almost the same tunnel behavior. In an evaluation using rock mass instead of intact rock, the data for the rock mass strength is plotted on the lower portion of the critical strain chart, as a way to compare to the data for intact rock strength. CONCLUSIONS : From the results of the pre-evaluation of stability of the tunnel using the critical strain chart, we reaffirmed that it is possible to promptly evaluate the stability of a tunnel under construction. Moreover, this research shows that a safety evaluation using the actual instrumented crown settlement data with the unconfined compression strength of intact rock, rather than with the unconfined compression strength of a rock mass in the tunnel working face, is more conservative.

• Journal of Families and Better Life
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• v.21 no.5
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• pp.13-24
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• 2003

Regarding leisure and work as very important in residential life of old ages, this study analyzed their preference by leisure and work for senior congregate housing, which can provide proper work and leisure activities for older people who are able to manage their social activities with healthy condition. It conducted a survey of middle aged of the 50's who would face problems of senior housing in 2010, with stratified sampling by region, sex and housing structure type. Totally 556 Questionnaires were used for the final analysis. The research results showed that, first, the group which was positive toward their works mostly had spouse of the age of early 50' s and work for professional, technological, managerial positions with good health. Second, the more positive group towards their work showed high willingness to move in senior congregate housing, than a negative group towards their work, and put a weight on the openness of shared space and facilities as well as various alarming equipments, common space, common programs and the ability of managers. Third, according to the attitudes toward leisure activities, there were differences in each group by housing structure type, education of their own or their spouses, monthly income, property, economic ability, health condition, living together with spouse, housing tenureship, and usable area of houses. The fourth was that those who enjoy active leisure activities presented high willingness to move in senior congregate housing than those of negative attitude and also there was a difference in managerial ways. Throughout the results of the study, it appeared that a group of positive attitude toward work and leisure, than that of negative attitude, recognized the importance of senior congregate housing which social and leisure programs could support. It implied necessary to develop housing for the older people who have enough ability to manage their leisure activity as well as their work. The study is likely to have a contribution to suggest practical data for helping the development of housing for self-reliant seniors by analyzing their preference on senior congregate housing by their attitudes toward work. The research for the factors of various designs and managements by leisure and work may become the following research theme of the study.

• Korean Journal of Social Welfare
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• v.61 no.4
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• pp.85-108
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• 2009

The quickening pace of international migration in the last twenty years brought fundamental demographic and social changes to the Korean society. Increasing number of marriage-based immigrant families imposes new challenges on social work community; however, the social work community has not been equipped with necessary practice models, sets of skills and professionals with cultural competency. This study aims to explore an integrative framework of social work practice with this client group. Research foci include the profile of marriage-based immigrant families in Korea, available social services at the time, challenges and issues they face, the compatibility of the empowerment based social work practice, and micro/mezzo/macro level concerns that arise for the effective service provision. Challenges among marriage-based immigrant families are converged into personal/familial, community related, and larger social-cultural issues. Empowerment is a multi-dimensional social process to help people gain control over their lives; a process that fosters power in people, for use in their lives, their communities and in their society. Empowerment based social work practice can be the most competent framework for working with multi-cultural families considering their multi-faceted acculturation issues while they navigate thru Korean society. Issues of educating and training of culturally competent social workers are discussed.

• The korean journal of orthodontics
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• v.48 no.1
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• pp.23-29
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• 2018

Objective: In accordance with the changing demographics in the United States, orthodontists working on various ethnic populations should be more conscious when using the standardized profile analyses for the African American patient. The objective of this study was to examine whether the perception of lip protrusiveness in modern African American faces has changed. For this purpose, we investigated the most favorable African American lip profile using the opinions of 10 experienced and 10 newly trained younger orthodontists. Methods: Attractiveness was converted to a number on visualized analog scales. Comparative ranks on 16 African American profiles, with focus on lip protrusiveness and thickness, were made among the groups. Mixed-effects linear regression models were fit and group differences were estimated. Results: Younger orthodontists favored a more protrusive lip profile, and the variance in their perceptions was narrower than those of older orthodontists. Measurements related to upper lip protrusion showed the strongest correlation to attractiveness (r = -0.82). The association with attractiveness decreased linearly as the protrusiveness of the upper lip increased. Steiner's E-line was the most influential reference for determining the level of attractiveness for the older orthodontists, whereas upper lip protrusion was the most influential factor for the young orthodontists. Conclusions: An adequate level of lip protrusiveness and thickness should be essential for maintaining attractive esthetics in African American patients. Yet, a new set of standards for prominent lips in this population is necessary to reflect the current trend in the concept of a beautiful face in the modern world.

• Korean Journal of Health Education and Promotion
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• v.12 no.1
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• pp.72-82
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• 1995

The purpose of this study was to review health and adjustment issues of Korean students in the context of international students' health in the United States. The number of international students studying in the United States has increased. In addition, more and more Koreans come to the United States for education. Korean students formed the fifth largest international group found on American campuses. As more and more international students study on American campuses, their health needs and problems became a concern to health professionals. Most health problems international students experience are stress related and psychosomatic. These students also have difficulties in using health care services. International students face barriers to obtaining health care because of differences in language and differences in cultural beliefs toward health. Korea manifests an eastern culture which is quite different from the western culture, so many Korean students studying in the United States experience difficulties in adjustment and using health care services. The study on the needs of Korean students in the U.S. reviewed in this research was a survey of 105 Korean students at the Pennsylvania State University, 1990. Korean students' health problems included stress, colds, fatigue, and headaches. Homesickness, financial problems, and academic problems were also important problems the Korean students faced. Korean students usually did not participate in any activities with Americans as much as with Koreans. Most Korean students did not participated in any health education workshops held on campus. This may be because the students had not participated previously in health education workshops conducted on campuses in Korea. Korean student's confidence with the English language appeared to be an important variable in using or not using the university health services. University health professionals in the United States need to develop better information system for international students so that they may better use the health services provided on campus. Also, university health professionals working on campuses in Korea need to put more attention on health of college students and provide on-campus health education workshops which meet the student's needs.