• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.47-53
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• 2012

Time-reversal (TR) precoding focuses the energy of the effective channel in time and improves receive performance of a single tap receiver. Frequency-domain equal-gain-combining (FD-EGC) TR scheme, which works in linear block precoding fashion, has better temporal focusing performance than the traditional TR. Also, the FD-EGC improves receive performance of minimum mean square error receiver with distributed antenna systems (DAS). The detailed receive performance of the FD-EGC was analyzed in our previous work. In this paper, we focused on capacity analysis of the FD-EGC in DAS. We derived a scaling law which shows how the use of multiple antenna can increase the capacity of the FD-EGC precoding compared with that of no precoding. In addition, we analyze the secrecy rate of the FD-EGC which shows how high-rate messages can be transmitted towards an intended user without being decoded by the other users from the view point of information theoretic security.

• Culinary science and hospitality research
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• v.16 no.3
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• pp.188-204
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• 2010

This research aims at finding relationship marketing factors that have positive effects on customer long-term orientation concerning wine purchasing personnels of domestic dinging companies such as sommeliers and managers. By figuring out the qualities of relationship such as the roles of trust and commitment while long-term orientation is being developed, it also tries to help wine suppliers which have been having a hard time due to domestic market recession and tight competition develop marketing strategies for promotion. A survey of wine purchasing personnels and sommeliers who work for fine dining restaurants, casual dining restaurants and wine bars was conducted for 30 days from Jan. 15, 2010 to Feb. 13, 2010. The statistical packages of SPSS 15.0 statistical package and AMOS 7.0 ver were used to perform frequency analysis, reliability test, confirmatory factor analysis, and path analysis. The result shows that among relationship marketing factors, communication and seller expertise have a positive impact on long-term orientation through trust and affective commitment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1191-1202
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• 2013

The former researches on earthwork automation were mainly focused on GPS and sensor application, environment modelling, equipment path planning, work information management, and remote control etc. Recently, reducing $CO_2$ emission becomes one of main focuses for an automation research. In the case of earthwork operations, many kinds of construction machines or robots are involved, which can cause high level of $CO_2$ in a construction site. An effective earthwork plan and construction machine operation can both increase productivity and safety and decrease $CO_2$ emission level. In this research, some automation concepts for green earthworks are suggested such as a 3D construction site model, a 3D earthwork distribution based on two different earthwork methods, and an earthwork package construction method. A excel-based simulator is developed to generate the 3D earthwork distribution and to estimate the level of $CO_2$ emission for the given earthwork.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2159-2166
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• 2000

Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger

• Journal of The Korean Association of Information Education
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• v.13 no.4
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• pp.433-441
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• 2009

In this research, we are looking for new ways to parents' participation in the school education through the educational information. The qualitative research about this research is not at all state. We use the method of study based on the grounded theory. The case analysis object is a outstanding school of the educational information in 2007, ten excellent schools of the cyber home service, two research schools 2 and two schools of research for NEIS. The parents make the learning check on situation of the students and communicate with school through the cyber home learning service and NIES. Also, It is bringing parents around the school closer through the SMS service and is communication path out of time and space. We make the things that make communications work through it. We know it is building trust with the parent and school.

• Journal of Advanced Navigation Technology
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• v.21 no.3
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• pp.264-271
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• 2017

This paper presents air traffic control simulation model for generating 4D trajectory, and aircraft dynamic model based on 4D trajectory information. With aircraft parameters from BADA and Total Energy Model, the trajectory is defined through modified Bezier curve and the simulation supports two aircraft control methods based on controlled time of arrival (CTA) or airspeed. The simulation results shown that flight time and path were almost identical to the defined trajectory, and derived the differences of each control methods according to wind conditions. Based on the simulation model developed in this study, it is expected to be applied to various air traffic management researches. Future studies will focus on applying optimization techniques in order to minimize the difference between generated trajectories and actual flight routes. This work will increase utilization of developed simulation futhermore.

• Journal of Distribution Research
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• v.2 no.2
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• pp.63-106
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• 1997

This study is conducted to examine the relationship between salespeople's job consciousness, their competencies of practical business and their turnover intention in department stores. The data was collected from 1961 department stores salespeople in Seoul and Sungnam. And a survey was conducted by questionnaire. Mean, Scheffe-test, Cronbach's ${\alpha}$, Perason's correlation, factor analysis, regression analysis, path analysis are used for the analysis of data. Major findings are as follows : 1) Job consciousness of salespeople is relatively strong, the level of competencies of practical business and turnover intention are somewhat low. 2) Job consciousness of salespeople and their competencies of practical business are related to their turnover intention. The more strongly they have job consciousness, the more highly they have the level of competencies of practical business, and the lower their turnover intention becomes. 3) Among related variables, their perception of distributive education shows the strongest effect on job consciousness of salespeople. Their job consciousness shows the strongest effect on competencies of practical business. Their job consciousness and competencies of practical business show the strongest effect on turnover intention of salespeople. 4) Turnover intention of salespeople is affected by the job consciousness directly or indirectly, and by competencies of practical business directly. Among related variable, age, experience degree on distribution education, period of work, educational level, marital status, jobs, the motive of choosing their occupation and sex show only indirect effects on their turnover intention through job consciousness and competencies of practical business of salespeople. The motive of choosing their occupation, importance degree on distributive education, sections of department stores(Clothing), perception degree on job specialization and selling experience show only direct and indirect effects on their turnover intention. Thus, job consciousness and competencies of practical business of salespeople are the major intervening variables which have strong negative effects on their turnover intention.

• Journal of The Korean Society of Integrative Medicine
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• v.8 no.2
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• pp.149-157
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• 2020

Purpose : The purpose of this study was that For high school students in Busan, in order to provide basic data in selecting dental hygienists by establishing the correct perception and image of dental hygienists by identifying the image of dentists and career doctors who will choose dental hygienists. Methods : The comparison of group differences with dental hygienists' images was analyzed with independent sample t-test and one-way ANOVA. Correlation between image factors of dental hygienists was analyzed using Pearson's correction coefficient. Results : The image for dental hygienists averaged 3.87 points overall, while the average for each area of the image was 4.09 points for professional images, 4.07 points for business images, 4.08 points for personal images and 3.28 points for social images. When choosing a career path, 18.8 percent said they would not consider dental hygiene, and if they said they would consider dental hygiene, both work, professional, personal and social images were significantly high (p<.05). Professional and professional images (r=.975, p<.05) in the correlation between factors of dental hygienist images, personal and professional images (r=.942, p<.05), social and professional images (r=.865, p<.05), business and personal images (r=.924, p<.05), business image and social image (r=.858, p<.05), personal and social images (r=.882, p<.05) expressed a statistically significant amount of correlation. Conclusion : The study found that high school students' image of dental hygienists was rather positive, but their social image was rather low, and most students did not consider dental hygiene. Therefore, specific measures will be needed to build a desirable image for dental hygienists and positively recognize dental hygienists with active promotion and career experience for dental hygienists in the future.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.53-53
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• 2011

As the dimension of Cu interconnects has continued to reduce, its resistivity is expected to increase at the nanoscale due to increased surface and grain boundary scattering of electrons. To suppress increase of the resistivity in nanoscale interconnects, alloying Cu with other metal elements such as Al, Mn, and Ag is being considered to increase the mean free path of the drifting electrons. The formation of Al alloy with a slight amount of Cu broadly studied in the past. The study of Cu alloy including a very small Al fraction, by contrast, recently began. The formation of Cu-Al alloy is limited in wet chemical bath and was mainly conducted for fundamental studies by sputtering or evaporation system. However, these deposition methods have a limitation in production environment due to poor step coverage in nanoscale Cu metallization. In this work, gap-filling of Cu-Al alloy was conducted by cyclic MOCVD (metal organic chemical vapor deposition), followed by thermal annealing for alloying, which prevented an unwanted chemical reaction between Cu and Al precursors. To achieve filling the Cu-Al alloy into sub-100nm trench without overhang and void formation, furthermore, hydrogen plasma pretreatment of the trench pattern with Ru barrier layer was conducted in order to suppress of Cu nucleation and growth near the entrance area of the nano-scale trench by minimizing adsorption of metal precursors. As a result, superconformal gap-fill of Cu-Al alloy could be achieved successfully in the high aspect ration nanoscale trenches. Examined morphology, microstructure, chemical composition, and electrical properties of superfilled Cu-Al alloy will be discussed in detail.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.76-76
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• 2011

Polymer-fullerene based bulk heterojunction (BHJ) solar cells can be fabricated in large area using low-cost roll-to-roll manufacturing methods. However, because of the low mobility of the BHJ materials, there is competition between the sweep-out of the photogenerated carriers by the built-in potential and recombination within the thin BHJ film [12-15]. Useful film thicknesses are limited by recombination. Thus, there is a need to increase the absorption by the BHJ film without increasing film thickness. Metal nanoparticles exhibit localized surface plasmon resonances (LSPR) which couple strongly to the incident light. In addition, relatively large metallic nanoparticles can reflect and scatter the light and thereby increase the optical path length within the BHJ film. Thus, the addition of metal nanoparticles into BHJ films offers the possibility of enhanced absorption and correspondingly enhanced photo-generation of mobile carriers. In this work, we have demonstrated several positive effects of shape controlled Au and Ag nanoparticles in organic P3HT/PC70BM, PCDTBT/PC70BM, Si-PCPDTBT/PC70BM BHJ-based PV devices. The use of an optimized concentration of Au and Ag nanomaterials in the BHJ film increases Jsc, FF, and the IPCE. These improvements result from a combination of enhanced light absorption caused by the light scattering of the nanomaterials in an active layer. Some of the metals induce the plasmon light concentration at specific wavelength. Moreover, improved charge transport results in low series resistance.