• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.809-819
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• 2004

In this paper, in order to exclude the expansion of M/W relay frequency or its new frequency assignment possibly, we analyzed a possibility of substituting M/W system by B-WLL or optical fiber network regarding service quality and economical points. To define the target of service quality, pre-condition and analysis method for the selected media have been derived to compare each other. E1 transmission with BER 10$^{-1}$ was chosen as a reference capacity, and service distance was calculated f3r the selected media as a function of availability. Also from the economical point we considered 3 systems such as optical fiber, M/W, and B-WLL based upon basic system structure, and analyzed them for various line configurations of fiber optic and B-WLL according to service period, system capacity, transmission distance, and data rate. It was confirmed that B-WLL can provide quality of service with 99.999 % availability within 1.6 km cell radius, and for optical fiber substitution, the leased fiber conduit on an electric pole is more economical than M/W system irrespective of service period, but in case of directly digging for underground conduit, it turned out ineffective regardless of cabling duct types.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.187-194
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• 2012

The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of $SiC_p$/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.52-60
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• 2016

Many hidden aspects of society around the world that has been lurking as risk factors have been ultimately connected to disasters. Such connection did not just stop with massive damages to properties and loss of lives but became a serious social issue. Especially in the case for Korea, because the country has gone through abrupt economic growth which has resulted in rapid urbanization and expansion of economic scale, Korea has been caught in a vicious cycle of experiencing human and social calamities repeatedly. Due to the seriousness of such problem, there's been continued research in various fields for managing disasters, and the domain of knowledge has been expanding with complexity. The following study went beyond the perspectives of disaster prevention study, disaster prevention engineering and social sciences suggested from previous research directions in disaster and disaster prevention, and attempted an alternative research method by approaching from a service design perspective. During the process, the paper looked over the summary on disaster and service design. By applying it on disaster prevention projects, the research sets forth and discusses effective and practical disaster prevention service design. Through specific case studies, the research methodology applied was verified, and the purpose of the study was carried out in the perspective of real world applications different from textbook type discussions. It is expected that through the disaster prevention service design process and platform that were discovered during the research result, defining and understanding disaster prevention service design will be made apparent. Additionally, the research is expected to be used as a basic building block for building a visualized plan for tangible and intangible factors related to disasters before the disaster process through such proposed disaster prevention service design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.274-282
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• 2020

This study examined the effect of job stress and mental health factors on the oral symptoms of caring service workers in Seoul. For the research method, a survey was conducted from July 24 to August 6, targeting 150 caring service workers. The survey items were job stress, mental health (physical symptoms, anxiety, and insomnia), and self-diagnosed oral symptoms. The results of the study were as follows. Job stress (p=0.001) had a significant effect on the oral symptoms. In addition, physical symptoms (p<0.001), anxiety symptoms (p<0.001), and insomnia symptoms (p<0.001) all had significant effects on the oral symptoms. Among the risk factors, physical symptoms had the greatest influence on oral symptoms. In addition, according to the correlation result of job stress, anxiety symptoms, insomnia symptoms, oral symptoms, as job stress increases, physical symptoms (p<0.001), anxiety symptoms (p<0.001), insomnia symptoms (p<0.001), oral symptoms (p<0.01) showed an increasing positive correlation and a statistically significant difference. Physical and psychological labor power is greatly exhausted by care service workers performing tasks that require physical and mental care for those who are being cared for. Therefore, there is a need for systematic expansion measures for the mental health of workers and the introduction of customized oral health education programs to improve oral health because improved health and oral health conditions can increase work performance.

• Korean Journal of Medicinal Crop Science
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• v.9 no.3
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• pp.211-219
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• 2001

The disease incidence rates of Phytophthora root rot of A. macrocephala caused by P. drechsleri were dramatically increased in two distinctive periods at experimental fields of National Crop Experiment Station(NCES), Suwon, in 1999 and in 2000 ; one was in the period of 30 to 45 days old seedling stage in spring and the other was just after heavy rainy season in late summer or in early fall. The disease was occurred at seedling stage under the conditions of ${{\geq}15^{\circ}C}$ of average temperature with ${{\geq}100mm}$ rainfalls for 20 days and the tendencies were similar in both year. By the disease, rhizome propagated field was more damaged(18.6%) than seed propagated field(56.0%). Comparing the disease incidence rates at five different fields in Suwon, Youngju and Andong, the damages at soil improving fields and non-mulching fields were less severe than those at continuous cropping fields without soil improvement and mulching fields and occurrence. Expansion of the disease were seemed to be highly related with the populations of P. drechsleri in soils depend on the cultivation method and field conditions. Although the populations of the pathogen in soils collected from Andong and Youngju, in which rhizome were continuously propagated for two and three years respectively, were comparably less than that from Suwon, in which rhizome were propagated for one year, however, the damages by the disease were more severe in Andong and Youngju. So, two or more years of cultivation at the same field may not be useful for Atractylodes plants..

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.282-291
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• 2010

This study is carried out in order to suggest the effective method to enhance the resettlement of natives for re-maintenance promotion district of Asansi. This study is carried out through current status survey, native survey, and examining related laws, and the result of study is as follows. First, as a result of examining the intention of resettlement for the residents and merchants who live in the project district, 84% of residents and 80% of merchants wish to resettle. Second, in order to enhance the rate of resettlement, driving project to satisfy the demands of residents and merchants is needed. For this, house supplying policy and complex design technique for corresponding this tendency is needed because they prefer to live a single houses or housing attached to shopping street of 100 million won valued below as well as apartments,. And new types of business which can activate the function of the old city are needed, but making commercial space where current merchants can constantly do business activities is demanded. Third, the expansion of urban regeneration concept which have economics, society, culture, welfare and community as well as physical environment improvement are emphasized is needed. Fourth, the role of government for urban regeneration should be strengthened, and institutional improvement should be supported. Government needs to constantly support including financial supporting in order for the regeneration of regional city, and especially should scout for the policies which community can be maintained and should support first. For this, utilizing public lands inside project district into leading project, government should utilize into "constructing rental houses for natives", inducing the leading key facilities. Fifth, various plan techniques for the resettlement of natives of other advanced countries should be examined and be achieved.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.2
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• pp.70-77
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• 2012

The Ladle Furnace Slag, about 20% of the electric arc furnace slag, has high content of free CaO and free MgO, which generates the expansion collapse by hydration reaction. Although many researchers have been endeavoring to recycle the EAF reducing slag in construction fields, there is not found the effective recycling method up to now. However, the LFS(Ladle Furnace Slag) contains mineral composition of the system of calcium aluminate with high-reactivity. Therefore, it is possible to developed the quick setting property and the high strength at the early age by the rapid cooling. This study aimed to check the reactive minerals and predict the reactivity with water on the LFS discharged from different steel product plants. The test results show that many types of LFS has hydration reactivity and can use in construction field as a inorganic binder with the rapid setting property.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.24-32
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• 2015

The global success of PSY's Gangnam Style was mediated through combination of YouTube and SNS. PSY's success led into some communication scholars' consideration of new international circulation of Korean pop culture (Korean Trend 2.0). In terms of global circulation of pop culture, it is noticeable how users appropriate YouTube channel beyond mere watching music videos and mere international circulation of Korean pop culture. The mode of fan's activity and appropriation contributes to the expansion of the width and amplification of the volume of Korean popular culture as well. The circulation of pop culture was considered in the level of exchange of tangible commodities such as CD, DVD, and so on until the adoption of digital media and Internet. YouTube has brought new mode in which the international circulation of pop culture is mediated without exchange of tangible commodities but was amplified with the diffusion of network. This study grasps how the mode of users' appropriation contributes to international circulation of pop culture through case studies of some K-pop music videos and international K-pop fans' tribute activities. In terms of theoretical perspective, fandom studies will be examined. In terms of research method, the researcher adopts netnography, a participatory observation on network, to find the feature of fandom and its contribution to the international circulation of pop cultures.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.101-109
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• 2010

There are many slopes generally developed by excavation and cut slope with small steps on massive slopes of roads. Especially these cut slopes which excavating around fault fracture zone need a reinforcement technology in order to ensure safety. In the case of slope excavation, it is difficult to use the existing slope support at fracture zone because of geological characteristics. Especially the factor of safety decreases significantly due to the movement of blocks in bed rocks and the expansion of interspace of discontinuous planes in fractured zones caused by excavation. Thus an efficient reinforcement technique in accordance with geological properties of fracture zones needs to be developed because the existing slope support has a restricted application. Therefore it is necessary to develop the specialized rock bolt technique in order to ensure an efficient factor of safety for anomalous fracture zones in slopes and tunnels. The purpose of this study is to develop newly improved rock bolt to increase a supporting effect of the swellex bolt method used recently as a friction type in fracture zones.

• Korean Security Journal
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• no.20
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• pp.119-140
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• 2009

It seems that security police's business to secure safety of state and citizens has existed since the mankind began to create a community. State was not fully responsible for such security business from the beginning. The business was carried out autonomously by the private sector for a long period. However, as the state system had been strengthened, the public sector absorbed the function. But in the modern society where various risks exist, safety of society could not be guaranteed only by public police. Accordingly, cooperation with the private sector is indispensable. In the limit of public police, autonomous organization of security companies and general citizens is expanding its scope. As a result, they should exercise partnership as a tripod to build social safety net. Security police failed to secure manpower exclusively responsible for security, despite various businesses and excessive mobilization. Accordingly, their professionalism and ability to cope with crisis are being questioned. In particular, efficiency of security police is becoming a more urgent issue in an era of international terrorism. Private sector can be classified into security companies and private autonomous organization. In case of security companies, the problem is quality and business ability of guards compared to a rapid external growth such as quantitative expansion and advancement into various businesses. In terms of pure private activity, the necessity of understanding of public police activity and conditions for organizational and continuous activity should be prepared. To tide over such problems and effectively achieve the common goal, changes in the method of employment, new establishment of security police department, and strengthening of professionalism and crisis management ability are necessary in the public police sector. In case of security companies, improvement of relations with public police through joint education, strengthening of business ability and activation of business cooperation through these matters are necessary. To maximize activity of pure private sector, it needs to establish reserve police, manage such private autonomous organization and bolster publicity with citizens.