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일반 진료 치과의사와 소아 진료 치과의사의 스트레스 유발 요인과 직무 스트레스 정도에 대한 연구
김승현,이제식 대한소아치과학회 2022 大韓小兒齒科學會誌 Vol.49 No.4
The purpose of this study was to compare factors causing stress in pediatric and general dentists when treating pediatric patients and to evaluate their overall occupational stress level. A total of 191 dentists participated in the online survey, consisting of 66 pediatric dentists and 125 general dentists. The questionnaire was conducted using Google Form. Both groups were stressed due to poor cooperation of patient and caregiver, uncertain prognosis of treatment, and low cost of pediatric dental treatment. The pediatric dentists felt relatively high stress due to poor cooperation from caregivers and an uncertain prognosis of treatment (p < 0.05). Overall occupational stress was high in both groups in the order of patient, time, job environment, and income-related stress, and the degrees of pediatric dentists were lower than general dentists. Among the 3 sub-factors of occupational burnout, more than 98% of both groups showed burnout in “depersonalization”, and more than 69% of both groups showed burnout in “emotional exhaustion”. Both groups showed a low burnout rate in “reduced sense of accomplishment” and pediatric dentists showed a higher sense of accomplishment than general dentists (p < 0.05). This study showed that both groups were under high occupational stress due to various factors, and efforts were required to relieve stress.
Electromechanical Properties of Pb(Zr, Ti)O$_3$ Films for MEMS Applications
김승현,Chang Young Koo,황철성,이동수,양정승,하조웅,Jung-Hoon Yeom,Kyu-Ho Hwang 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
A systematic investigation of the piezoelectric and ferroelectric properties of PZT lms prepared by chemical solution deposition is performed for tetragonal (Zr/Ti = 30/70), morphotropic (52/48), and rhombohedral (70/30) composition. An atomic force microscope (AFM) is used to measure the magnitude of the eective longitudinal piezoelectric coecient (d33) of these lms. All lms are consistently highly textured (111) orientation and have dense microstructures. Slightly less degree of texture in higher Zr-rich composition is observed due to the lattice mismatch between PZT and Pt bottom electrode and higher activation energy for nucleation. Squareness of polarization hysteresis loops is optimized in tetragonal composition, which indicates the tetragonal PZT is closer to the ideal hysteresis behavior than other composition. It is shown that the piezoelectric coecient is dependent on the dielectric constant. The morphotropic PZT lms with 1 m thickness show the largest piezoelectric coecient values, which are comparable with those of bulk materials.
Scaling Issues of Pb(Zr, Ti)O$_3$ Capacitor Stack for High Density FeRAM Devices
김승현,Chang Young Koo,황철성,이동수,Dong-Yeon Park,Jieun Lim,하조웅,Jung-Hoon Yeom 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
For realization of 32 Mb high density FRAM devices, the low stack height of capacitor from 750 nm to 300 nm should be accomplished with the scaling of thickness of PZT thin lms and electrodes below 100 nm. Otherwise, it is not possible of each capacitor to retain sucient distance with adjacent capacitors due to the diculty in obtaining steep etching slope of the capacitor, and which induces a critical device failure. To address these issues we explore the ferroelectric performance of the thickness scaled PZT thin lms (35 70 nm) on ultra thin bottom Pt electrodes (30 nm). It is observed that the switching performance of the thickness scaled PZT thin lms on sub-50 nm thick Pt bottom electrodes showed 1 V operation with sharp and rectangular hysteresis loops and high remanent polarization values (30 35 C/cm2), implying the possibility to realize 32 Mb FRAM devices and beyond. For a long-term stability of the capacitors, the lm thicknessdependent imprinting behavior was evaluated by a thermal stress process under a remanence bias. It is found that the voltage shift, which was attributed to the accumulation of charged defects near the electrode interface, increased linearly with increasing the lm thickness.