• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.981-984
• /
• 2001

The piezoelectric properties of 0.05pb(A $l_{0.5}$N $b_{0.5}$) $O_3$-0.95Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$+0.7wt%N $b_2$ $O_{5}$ +0.5wt%Mn $O_2$ceramics with the additives of BaC $O_3$were investigated. For the additions of BaC $O_3$, the dielectric constant ($\varepsilon$$^{T}$ $_{33}$ ), the piezoelectric constant ( $d_{33}$ ), the electromechanical coupling factor ( $k_{p}$ ), and . the mechanical quality factor ( $Q_{m}$ ) were increased, but dielectric loss (tan$\delta$) was decreased. The highest piezoelectric properties and dielectric properties were observed at the sintered temperature of 120$0^{\circ}C$ and 0.4 wt% of BaC $O_3$, and the properties of $d_{33}$ , $k_{p}$ , and $Q_{m}$ were 339(x10$^{-12}$ C/N), 59% and 1754, respectively.vely.y.y.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.11a
• /
• pp.149-152
• /
• 1997

High-power piezoelectric materials are being developed for applications such as actuators and ultrasonic motors. In this paper, ferroelectric property of iron-doped 0.57 (Sc$_{1}$2//Nb$_{1}$2/)O$_3$-0.43 PbTiO$_3$. which is the morphotropic phase boundary composition for the PSN-PT system, was investigated. The maximum dielectric constant ( $\varepsilon$$_{33}$/$\varepsilon$$_{0}$ = 2551) and the minimum dielectric loss(tan $\delta$ = 0.51 %) at room temperature were obtained at 01. wt% and 0.3 wt% of iron additions. With additions of the Fe$_2$O$_3$ the electromechanical coupling factor of radial mode k$_{p}$ and the piezoelectric coefficient d$_{33}$ were slightly decreased, on the other hand the mechanical quality factor was increased significantly. The highest mechanical quality factor (Qm= 297) was obtained at 0.3 wt% Fe$_2$O$_3$, which is 4.4 times larger than that of pure 0.57 PSN-0.43PT ceramics. The temperature dependence of the dielectric constant and dielectic loss was observed between 2$0^{\circ}C$ and 35$0^{\circ}C$ .X> .X> .

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.672-681
• /
• 2018

This study was conducted to test the validity and reliability of the Korean version of the Professional Quality of Life Scale-Short Form (ProQOL-K-SF). Survey data were collected from 191 staff involved in long-term care insurance who worked for National Health Insurance Services. Construct validity using exploratory factor analysis and the internal consistency reliability were determined using SPSS/WIN (21.0). Factor analysis of the ProQOL-K-SF demonstrated that it has a two-factor structure (compassion satisfaction and compassion fatigues) and 13 items that support construct validity. Factor loadings of the compassion satisfaction ranged from 0.70-0.86, factor loading of the compassion fatigues ranged from 0.71-0.82 and the total variance was 60%. The ProQOL-K showed interanal consistency based on Cronbach's ${\alpha}$, with a total scale and two sub scale values of 0.76-0.90. Compassion fatigue and compassion satisfaction of 30 items of the ProQOL-K were positively correlated with those of 13 items of the ProQOL-K-SF. The results support that the ProQOL-K has satisfactory construct validity and is a reliable measure of professional quality of life in Korea.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.71-74
• /
• 2002

In this study, resonant characteristics of $Pb_{0.88}(La_{0.6}Nd_{0.4})_{0.08}(Mn_{1/3}Sb_{2/3})_{0.02}Ti_{0.98}O_3$ ceramics were investigated with the variations of electrode radius size for manufacturing the best 30MHz SMD type ceramic resonator with the size of $3.7{\times}3.1{\times}0.255mm^3$. Physical properties were proper for appling for 30MHz SMD type ceramic resonator. In third overtone thickness vibration mode, with increasing electrode radius size, resonant resistant($Z_r$) was decreased gradually. Mechanical quality factor($Q_{mt3}$) and dynamic range(D.R) showed the maximum value of 2,283, 47.1dB respectively, at 0.74mm electrode radius size.

• Journal of the Korean Ceramic Society
• /
• v.56 no.4
• /
• pp.399-402
• /
• 2019

The phase evolution, microstructure, and microwave dielectric properties of (Ba_1-xNa_x)(Mg_0.5-2xY_2xW_0.5-xTa_x)O₃ (0 ≤ x ≤ 0.05) ceramics were investigated. All compositions exhibited a 1:1 ordered perovskite structure. As the value of x increased, the dielectric constant (ε_r) exhibited a tendency to increase slightly. The quality factor reached the maximum value at x = 0.01. The temperature coefficient of resonant frequency (τ_f) increased from -19.32 ppm/℃ to -5.64 ppm/℃ in the positive direction as x increased. The dielectric constant (ε_r), quality factor (Q × f₀), and temperature coefficient of resonant frequency (τ_f) of the composition x = 0.05, i.e., (Ba_0.95Na_0.05)(Mg_0.4Y_0.1W_0.45Ta_0.05)O₃ were 19.9, 128,553 GHz, and -5.6 ppm/℃, respectively.

• Quality Improvement in Health Care
• /
• v.8 no.1
• /
• pp.74-83
• /
• 2001

Background : Since a Gamma Knife had been installed on December 1997, 405 patients have been treated until December 1999 at department of neurosurgery of Seoul National University hospital. The authors analyzed results of a work to improve satisfaction of Gamma Knife surgery patients and to reduce hospital length of stay. Methods : To understand main discontent of patients, a pre-survey was performed from October 1998 to December 1999 using a questionnaire. By Analyzing 93 questionnaire received from 234 patients, pain on frame application, explanation before surgery, waiting time before surgery, waiting time before medical procedure were main discontent factor and overall satisfaction ratio was 71.0%. To improve satisfaction ratio, several quality improvement activity works were designed and applied to 123 patients during the period between January 2000 and September 2000. The same questionnaire were analyzed. Works to reduce the patient hospital LOS were devised and applied during the same period. Results : The overall satisfaction ratio of Gamma Knife radiosurgery patients was increased to 83.7%(P=0.10). The main factor to improve satisfaction ratio was to reduce waiting time(P=0.05) and improvement of discomfort during the surgery(P=0.06). The average LOS was reduced from 3.1 to 2.7 days(P=0.003). Conclusion : As a result of quality assurance activities, the overall satisfaction ratio of patients was improved and LOS was reduced. The pain during frame application was remained as a main discontent factor and a further study is required to reduce this pain.

• Fashion & Textile Research Journal
• /
• v.18 no.1
• /
• pp.103-112
• /
• 2016

This research was designed to figure out the perception and attitude of university students toward urban outdoor wear and to provide the guidelines for product quality improvement using Kano model. A total of 270 responses were analyzed by SPSS 20.0 through frequency and factor analysis. Respondents' levels for outdoor activity & outdoor products possession being still low, steady growth in urban outdoor wear market is expected. A total of eight quality factors were identified through factor analysis; suitability, production quality, functionality, ease of care, fabric performance, portability, fashionability, and symbolism. Based on Kano model, quality factors of urban outdoor wear were categorized into three groups: one-dimensional; indifferent; and must-be quality factor. It was found that consumers were satisfied with urban outdoor wear only when it meets the needs for suitability for body types and ease of care, meaning that manufactures should be cautious not to lose these features. Being must-be quality factor, production quality(form stability, quality of subsidiary materials), and fabric performance such as colorfastness should be basically satisfied. The relative importance of each quality feature on satisfaction/dissatisfaction was investigated using CSC(customer satisfaction coefficient). Based on the CSC, every item was classified again. Attractive quality features with large CSC were shown in suitability factor. Must-be quality features with small CSC were mainly shown in functionality and fabric performance factors. These findings imply that manufactures of urban outdoor wear should not only maintain the production quality but also focus on suitability features to differentiate their product with previous products.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.806-808
• /
• 2001

In this thesis, specimens was manufactured in general method annexing PMB-PZT system ceramic, and the following conclusion has been deduced. In XRD, the crystal structure of ceramic has the tetragonal structure which is close to rombohedral structure, and consequently the specimen characterized by MPB was manufactured. According to dopping with xPMB, electromechanical factor(kp) little is changed. kp was maximum value 23.37[%] at xPMB 0.03[mol%]. mechanical quality factor(Qm) was maximum value 237.04 at xPMB 0.03[mo1%].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.578-580
• /
• 2002

In this thesis, specimens was manufactured in general method annexing PMB-PZT system ceramic, and the following conclusion has been deduced. In XRD, the crystal structure of ceramic has the tetragonal structure which is close to rombohedral structure, and consequently the specimen characterized by MPB was manufactured. According to dopping with xPMB, electromechanical factor(kp) little is changed. kp was maximum value 23.37[%] at xPMB 0.03[mol%]. mechanical quality factor(Qm) was maximum value 237,04 at xPMB 0.03[mol%].

• Journal of Preventive Medicine and Public Health
• /
• v.38 no.1
• /
• pp.61-70
• /
• 2005

Objectives : To develop a tool for multidimensional measurement of the quality of life, which was psychometrically sound, short, and easy to administer for patients with hypertension. Methods : A sample of 1,115 hypertensive patients aged 20 or above in Cheong-Song County was studied from June 1997 to October 1998. In the development of the instrumental stage, the authors first conceptualized the quality of life. Item generation, item reduction, and questionnaire formatting were followed. Item-level (item descriptive, missing%, item internal consistency, item discriminant validity) analysis, scale-level (scale descriptive, floor and ceiling effect) analysis, and other tests(Cronbach's alpha, inter-dimension correlations, factor analysis, clinical validity) were performed to evaluate the validity and reliability of the new measurement scale. After 1 year, responsiveness and confirmatory factor analysis were performed. Results : The results of both item-level and scale-level analyses were acceptable. An acceptable degree of internal consistency was observed for each of the dimensions (Cronbach's alpha was 0.60 or higher). Inter-dimension correlations were below 0.50 and the factor analysis result was the same as the intended dimension structure. Correlation coefficients between perceived health status, stress and dimensions were proven to be acceptable. The result of comparing dimensional score means among ADL and MMSE-K groups above 60 years was statistically significant(p<0.05). The result of confirmatory factor analysis concluded that the dimensional structure model was well fitted. However, the result of responsiveness test using sensitivity and specificity was unsatisfactory. Conclusions : The newly developed measurement scale is psychometrically reliable and valid instrument for measuring quality of life in hypertensive patients.