• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.821-825
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• 2004

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PMN-PZT ceramcis using $Li_2CO_3$ and $Bi_2O_3$ as sintering aids were manufactured, and their microstructural, dielectric and piezoelectric properties were investigated. The sintering aids were proved to lower the sintering temperature of piezoelectric ceramics due to the effect of $LiBiO_2$ liquid phase. At 0.1wt% $Li_2CO_3$ added specimen sintered at $970[^{\circ}C]$, electromechanical coupling factor(Kp), mechanical quality factor(Qm) and dielectric constant showed the optimum values of 0.50, 2,413 and 1,245, respectively, for multilayer piezoelectric transformer application.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.5 s.153
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• pp.663-673
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• 2006

The purpose of this study is to seek for a plan of marketing strategy in the businesses of Korean clothes, by examining the causality among marketing factors, which have influenced CRM(Customer Relationship Management) performance in Korean clothes. As for the research method, a research model was designed to include routes form 4P's(products, price, promotion, place) through endogenous variables to performance variables, and a questionnaire was developed on the basis of theoretical background. The research participants were male and female adults at their age from 20 to 60. The survey was conducted in March of 2003, and 672 questionnaires were used for the final analysis. In terms of data analysis, we carried out reliability analysis, exploratory and confirmatory factor analysis, correlation analysis, and Structural Equation Modeling by using SPSSWIN 10.0 and AMOS 4.0. As a result 4P's were indicated to have influence upon confidence, satisfaction and commitment of customers. Especially, sales promotion factor was found to have the biggest impact on them. also, the quality of relationship affected CRM performance. as sales promotion factor was identified as one of the integral elements of marketing strategies, a strategy that utilizes a role of salespeople and enhances the quality of service is needed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.255-256
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• 2007

In the study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, PMN-PNN-PZT ceramics were fabricated using $Na_2CO_3,\;Li_2CO_3$ as sintering aids and their dielectric and piezoelectric properties were investigated according to the variations of $MnO_2$ as additives and sintering aids. At the sintering temperature of $900^{\circ}C$ and 0.1wt% $MnO_2$ as sintering aids, density, electromechanical coupling factor$(k_p)$, mechanical quality factor$(Q_m)$, piezoelectric constant$(d_{33})$, and dielectric constant $({\varepsilon}_r)$ showed the optimum value of $7.87[g/cm^3]$, 0.61, 1131, 1127 and 376, respectively, for multilayer piezoelectric actuator application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.285-289
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• 2011

In this study, lead-free $(K_{0.5}Na_{0.5+X})(Nb_{0.96}Sb_{0.04})O_3+0.2mol%La_2O_3+1.2mol%$ $K_4CuNb_8O_{23}$ (X= 0~0.025) ceramics were fabricated by normal sintering method at $1060^{\circ}C$ for 5 h. Microstructures, piezoelectric and dielectric properties of specimens were investigated with special emphasis in the influence of Na excess addition. The grain size of specimen was slightly decreased with increasing Na content. In the 2 [mol%] Na excess addition of NKNS ceramics, density, electromechanical coupling factor, piezoelectric constant and electromechancal quality factor of specimen were found to reach the optimum values of 4.25 [$g/cm^3$], 0.4357, 154.43 [pC/N] and 580, respectively.

• Journal of Korean society of Dental Hygiene
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• v.15 no.6
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• pp.1117-1123
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• 2015

Objectives: The purpose of the study was to examine the influencing factors of oral health-related quality of life in adults. Methods: A self-reported questionnaire was completed by 300 adults in Seoul and Gyeonggido from June to July, 2015 by convenience sampling method. Except 19 incomplete answers, 281 data were analyzed by t test, one way ANOVA, Pearson's correlation coefficient analysis, and multiple linear regression analysis using SPSS 18.0 program. The questionnaire consisted of general characteristics of the subjects, health-related characteristics, whole body dry symptoms and subjective perception of dry mouth. The oral health-related quality of life was measured by Likert five points scale, and a higher score indicated a lower quality of life. Results: The oral health-related quality of life in adult varied by age, systemic diseases, oral health status, missing tooth, stress, decayed tooth, gingival disease. The oral health-related quality of life had positive correlations with the subjective perception of dry mouth and whole body dry symptoms. The subjective perception of dry mouth(${\beta}$=0.245) had the influence on the oral health-related quality of life, oral health status(${\beta}$=-0.209), gingival disease(${\beta}$=-0.151), and decayed tooth(${\beta}$=-0.146) in order. Conclusions: The oral health-related quality of life was closely related to the subjective perception of dry mouth and the oral health status. It is necessary to develop the quality of life improvement programs including oral health prevention and care program in the adults.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.183-192
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• 2002

Indoor air quality is affected by source strength of pollutants, ventilation rate, decay rate, outdoor level and so on. Although technologies exist to measure these factors directly, direct measurements of all factors are impractical in most field studies. The purpose of this study was to develop an alternative methods to estimate these factors by multiple measurements. Daily indoor and outdoor NO$_2$concentrations for 21 days in 20 houses in summer and winter, Seoul. Using a mass balance model and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor(emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the ventilation and source strength were estimated. During sampling period, geometric mean of natural ventilation was estimated to be 1.10$\pm$1.53 ACH, assuming a residential NO$_2$decay rate of 0.8 hr$^{-1}$ in summer. In winter, natural ventilation was 0.75$\pm$1.31 ACH. And mean source strengths in summer and winter were 14.8ppb/hr and 22.4ppb/hr, respectively. Although the method showed similar finding previous studies, the study did not measure ACH or the source strength of the house directly. As validation of natural ventilations, infiltrations were measured with $CO_2$tracer gas in 18 houses. Relationship between ventilation and infiltration was statistically correlated (Pearson r=0.63, p=0.02).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.1-7
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• 2008

In this paper, we propose a lossy MTM transmission line unit cell and retrieve the parameter values related with radiation effects. Based on this unit cell model, we plot dispersion diagrams and analyze resonance conditions. We also discuss the input impedance or admittance behavior when we terminate the load as open or short. Then, we examine the quality factor and return loss bandwidth. We also design a very compact unit cell antenna using the provided lossy MTM-TL model. The results based on EM simulations and measurements are shown to be in good agreement with those based on circuit simulation.

• Progress in Medical Physics
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• v.21 no.1
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• pp.120-125
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• 2010

For the measurements of an absorbed dose using the standard dosimetry based on an absorbed dose to water the variety of factors, whether big, small, or tiny, may influence the accuracy of dosimetry. The beam quality correction factor ${\kappa}_{Q,Q_0}$ of an ionization chamber might also be one of them. The cylindrical type of ionization chamber, the PTW30013 chamber, was chosen for this work and 9 chambers of the same type were collected from several institutes where the chamber types are used for the reference dosimetry. They were calibrated from the domestic Secondary Standard Dosimetry Laboratory with the same electrometer and cable. These calibrated chambers were used to measure absorbed doses to water in the reference condition for the photon beam of 6 MV and 10 MV and the electron beam of 12 MeV from Siemens ONCOR. The biggest difference among chambers amounts to 2.4% for the 6 MV photon beam, 0.8% for the 10 MV photon beam, and 2.4% for the 12 MeV electron beam. The big deviation in the photon of 6 MV demonstrates that if there had been no problems with the process of measurements application of the same ${\kappa}_{Q,Q_0}$ to the chambers used in this study might have influenced the deviation in the photon 6 MV and that how important an external audit is.

• Journal of Korean Library and Information Science Society
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• v.30 no.4
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• pp.183-206
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• 1999

The purpose of this research is to evaluate the service quality measure and service quality level between one sample library and the other. Most typically, service quality is defined in terms of reducing the gap between customer expectations and the actual service provided. This research also focuses on gap reduction. Service quality concept was originally discussed in a commercial environment and may require some adaptation to the non-commercial environment of the academic library. A revised service quality measure that developed by P. J. Calvert and P. Hernon(1996) was used for this research. Results showed that service quality measure of this research was reliable(99 service quality items scale's Cronbach Alpha coefficient was 0.983) and was validated by correlation and factor analysis. Therefore service quality measure of this research will be applied positively for academic libraries. And this research showed that the service quality level of sample academic library was inferior to that of the others. The service quality of sample academic library should be improved to meet the customer's needs and expectations immediately.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.150-154
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• 2019

This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$, which has a rhombohedral-tetragonal phase boundary composition. $MnO_2$ and CuO-added $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$ ceramics sintered at a relatively low temperature of $1020^{\circ}C$ show a pure perovskite phase with no secondary phase. As the addition of $MnO_2$ and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of $MnO_2$.