• Korean Journal of Materials Research
• /
• v.12 no.1
• /
• pp.75-81
• /
• 2002

The ferroelectric properties of Pb(Zr,Ti)O$_3$[PZT] films degrade when the films with Pt top electrodes are annealed in hydrogen containing environment. This is due to the reduction activity of atomic hydrogen that is generated by the catalytic activity of the Pt top electrode. At the initial stage of hydrogen annealing, oxygen vacancies are formed by the reduction activity of hydrogen mainly at the vicinity of top Pt/PZT interface, resulting in a shift of P-E (polarization-electric field) hysteresis curve toward the negative electric field direction. As the hydrogen annealing time increases, oxygen vacancies are formed inside the PZT film by the inward diffusion of hydrogen ions, as a result, the polarization degrades significantly and the degree of P-E curve shift decreases gradually. The direction and the magnitude of the remnant polarization in the PZT film affect the motion of hydrogen ions which determines the degradation of polarization characteristics and the shift in the P-E hysteresis curve of the PZT capacitor during hydrogen annealing. When the remnant polarization is formed in the PZT film by applying a pre-poling voltage prior to hydrogen annealing, the direction of the P-E curve shift induced by hydrogen annealing is opposite to the polarity of the pre-poling voltage. The hydrogen-induced degradation behavior of the PZT capacitor is also affected by the internal field that has been generated in the PZT film by the charges located at the top interface prior to hydrogen annealing.

• Journal of Korean Academy of Nursing
• /
• v.25 no.4
• /
• pp.709-728
• /
• 1995

The job related activities of sixty nine nurses, working in the emergency rooms of three university hospitals, were analyzed for six days according to preestablished checklist of nursing activities ; the frequency of these activities and the amount of time spent in each specific nursing activity. The established checklist was monitored every five minutes for the duration of the duty autu, thus producing 414 items of data. The data were not gathered on consecutive days but over the period of one month from May 6, 1994 to June 5, 1994. The following conclusions are derived from analysis of the data : 1. Twelve categories of nursing activities were obtained : The primary activity was communication related to the patient and all information pertaining to the patient. Other activities included maintaining the patient's record, observation and assessment of the patient, cooperation with other medical personnel, management of equipment and drugs, procedure and treatment, specimen collection, consultation and education for the patient, including drug management and personal hygiene and any other relevant education to the patient's condition. 2. The average frequency of categorized nursing activity can be classified as follows : communication related to patient was the highest at 17.6 times. The next was maintaining the patient's record at 17.3 times. The observation and assessment occurred 16.9 times. Consultation and education for patients and family, 8 times, medication, 5.7 times, and procedures and treatments, 6 times. 3. The average time required for each activity was as follows : 230.1 minutes (or maintaining the patient's record, 204.9 minutes for communication related to the patient, 199.2 minutes for observation and assessment, 71.2 minutes for medication, 66 minutes for consultation and education of the patient and family, and 51.8 minutes for procedures and treatment. 4. The most demanding nursing activity in the emergency room for the nurse was answering questions from the patient's family, maintaining communication between the medical staff, maintaining and reviewing the patient's charts, writing prescriptions and monitoring 1. V. infusion rates. 5. The most time consuming nursing activities for the emergency room nurse include maintaining and following the patient's charts, communication between the medical staff, answering questions from the patient's family, observation of the patient and relaying all of the appropriate patient information to the incoming nurses during a shift change. 6. The F-test was administered to measure the required time for the categorized nursing activities according to day, evening, and night-shift nurses. There were significant differences (p<.05) in specimen collection, observation and assessment, cooperation between medical staffs, personal hygiene, communication related to patient, education and re-search. Posterior multiple comparison test showed that specimen collection, cooperation between medical staffs and personal hygiene were mostly done by the evening-shift nurses. Also most observations and assessments were done by the night-shift nurses. Education and communication to patients were done by day-shift nurses. Thus there were significant difference between shifts for the main nursing activities. So there should considev a reallocation of the duty of nurses on each shift. 7. The F-test also indicated that there wes a similarity in time duration for procedures and treatments and for cooperation between medical staff and nurses in all three hospitals. However, the remaining categories of nursing activities also showed a significant difference between the three hospitals. This indicated that there were differences in each emergency room that influence time for each categorized nursing activities and this should be given more consideration. Recommendations : 1. A seasonal difference should be considered in the activities of nurses in the emergency room and a comparative analysis should be carried out to deter-mine seasonal differentiation. 2. A study on more objectively measurable nursing activities should be administered as well as one determining the subjective responds towards nursing activities in the emergency room.

• Journal of The Korean Astronomical Society
• /
• v.33 no.2
• /
• pp.89-95
• /
• 2000

As an efficient method to detect blending of general gravitational microlensing events, it is proposed to measure the shift of source star image centroid caused by microlensing. The conventional method to detect blending by this method is measuring the difference between the positions of the source star image point spread function measured on the images taken before and during the event (the PSF centroid shift, ${\delta}{\theta}$c,PSF). In this paper, we investigate the difference between the centroid positions measured on the reference and the subtracted images obtained by using the difference image analysis method (DIA centroid shift, ${\delta}{\theta}$c.DIA), and evaluate its relative usefulness in detecting blending over the conventional method based on ${\delta}{\theta}$c,PSF measurements. From this investigation, we find that the DIA centroid shift of an event is always larger than the PSF centroid shift. We also find that while ${\delta}{\theta}$c,PSF becomes smaller as the event amplification decreases, ${\delta}{\theta}$c.DIA remains constant regardless of the amplification. In addition, while ${\delta}{\theta}$c,DIA linearly increases with the increasing value of the blended light fraction, ${\delta}{\theta}$c,PSF peaks at a certain value of the blended light fraction and then eventually decreases as the fraction further increases. Therefore, measurements of ${\delta}{\theta}$c,DIA instead of ${\delta}{\theta}$c,PSF will be an even more efficient method to detect the blending effect of especially of highly blended events, for which the uncertainties in the determined time scales are high, as well as of low amplification events, for which the current method is highly inefficient.

• Safety and Health at Work
• /
• v.10 no.1
• /
• pp.109-113
• /
• 2019

Background: In both developed and developing countries, noise is regarded as the most common occupational hazard in various industries. The present study aimed to examine the effect of sound pressure level (SPL) on serum cortisol concentration in three different times during the night shift. Methods: This case-control study was conducted among 75 workers of an industrial and mining firm in 2017. The participants were assigned to one of the three groups (one control and two case groups), with an equal number of workers (25 participants) in each group. Following the ISO 9612 standard, dosimetry was adopted to evaluate equivalent SPL using a TES-1345 dosimeter. The influence of SPL on serum cortisol concentration was measured during the night shift. The serum cortisol concentration was measured using a radioimmunoassay (RIA) test in the laboratory. Repeated measure analysis of variance and linear mixed models were used with ${\alpha}=0.05$. Results: The results indicated a downward trend in the serum cortisol concentration of the three groups during the night shift. Both SPL and exposure time significantly affected cortisol concentration (p < 0.0001, p < 0.0001). Conversely, age and body mass index had no significant influence on cortisol concentration (p = 0.360, p = 0.62). Conclusion: Based on the obtained results, increasing SPL will lead to enhancement of serum cortisol concentration. Given that cortisol concentration varies while workers are exposed to different SPLs, this hormone can be used as a biomarker to study the effect of noise-induced stress.

• Journal of the Korean Regional Science Association
• /
• v.32 no.4
• /
• pp.39-49
• /
• 2016

The main objective of this paper is to analyze university students' modal shift for commuting trip due to the introduction of new urban rail transit in a satellite city of metropolitan area. The paper uses SP(2011)/RP(2013) data collected from Yeungnam University in Gyeongsan City, which is a satellite city of Deagu Metropolitan City. So far few researches, especially using before-and-after individual SP/RP travel survey, have been conducted on analyzing university students' modal shift due to the introduction of new urban rail transit. For this research, some descriptive statistical analyses were conducted. Furthermore, some empirical logit models were estimated for analyzing factors affecting the modal shift. Finally, some important findings and policy implications are discussed. The significant findings from this research are summarized as follows. From the descriptive statistical analyses of SP and RP data, it is found that the rate of modal shift to rail transit is relatively high especially for bus travellers. Furthermore, from the empirical SP model estimation, it is found that time saving is the most important factor affecting the modal shift to urban rail transit. On the other hand, from the empirical RP model estimation, it is found that residential location is the most important factor affecting the modal shift to urban rail transit.

• Ocean and Polar Research
• /
• v.30 no.1
• /
• pp.11-19
• /
• 2008

Incubation routine and sex role of Streaked Shearwaters Calonectris leucomelas at Sasudo Island, in Jeju, South Korea, were studied during the incubation period, June to August in 2002. Incubation routine in Procellariiformes represents a sequence of alternating shifts taken in turn by female and male in a species-specific pattern. Hence, coordination of individual incubation rhythms between partners is crucial for successful breeding attempt. In Streaked Shearwaters, incubation routine represents a sequence of alternating shifts taken in turn by male and female. The first incubation shift was made by male after female had laid the egg. The mean incubation period was 50.8 days until hatching. Males had spent on average 26.5 days incubating and females 24.3 days accordingly. The mean duration of incubation shifts decreased progressively from 6th and 7th shift to hatching. Overall, males had spent more time incubating than females during the incubation period, but the mean duration of the incubation shift 5.6 days for males and 5.7 days for females did not differ between males and females. There were no effect of the body size of the breeding pair on incubation performance. For males the mean of body weight decreased during the incubation, whereas for females it remained approximately stable. In Streaked Shearwaters, the duration of incubation shift and subsequent foraging trip are related to loss of body weight during the period of fasting. In addition, coordination of individual incubation rhythms affects their incubation behaviour.

• Journal of Korean Academy of Nursing Administration
• /
• v.5 no.3
• /
• pp.513-524
• /
• 1999

The shortage of nursing personnel was become one of the most serious problems in operating pediatric oncology nursing unit which was the first pediatric oncology nursing unit in Korea. The purpose of this study was to estimate the optimal number of nursing personnel by calculating nursing care hours. The subjects were 13 staff nurses and inpatients of pediatric oncology nursing unit at Seoul National University Hospital during the period of May 20, 1996, to June 2, 1996. The number of nurses' duty was 132, the number of patients treated was 1288 for these 2 weeks. The tools used for this study were pediatric patient classification indexes and direct & indirect care indexes. Each nurse measured the time that they spent for their activities by self record under the supervision of their nurse manager. The method used to calculate the number of nursing personnel was multiplication of the average number of nursing care hours per patient per day with the number of patients. Percentage, average, t-test, F-test were used for data analysis. The results of this study were as follows : 1) The distribution of patient class : Class I & II none, Class III 86.8%. Class IV 12.9% 2) Direct nursing care hours for a patient per shift according to patient classification: Class III : 27.64 minutes, Class IV : 54.64 minutes The average direct nursing service hours for a patient per shift(3 shift) was 31.54 minutes(94.62 m/day). The average indirect nursing service hours for each patient per duty(3 shift) is 21.3 minutes (63. 91 m/day). 3) The average nursing hours for a patient per duty was 52.80 minutes(2.64h/day). 4) The group of administering medications in direct care activities showed the highest percentage (38.9%). Checking vital signs among observation took the most time am.ong each direct care activity (6.88 minutes for a patient per duty). 5) Charting took the most time of each indirect care activity(52.53 minutes/ duty/nurse). 6) The average personal time per duty is 29.40 minutes, which 'was below 30 minutes of this hospital regulations. 7) The average nursing hours that a nurse provided for a duty was 8.60 hours, which meant that a nurse worked 1.10 hours overtime. 8) Standardizing to a 33 bed to a unit, 17 nurses were needed at the present nursing level.

• Journal of the Korea Convergence Society
• /
• v.12 no.7
• /
• pp.295-304
• /
• 2021

This study is a secondary data analysis to investigate the nursing tasks performance, appropriate performer, and job satisfaction in the general wards with sift work. We found that nurses performed direct (45%) and indirect nursing (55%). The workload per shift was 37.2% in the day, 35.6% in the evening, and 27.2% at night. The tasks performed after handover were 'direct nursing (34.5%)' and 'documentation and notification (25.8%)'. Nurses responded that there were some tasks that could be delegated to nursing assistants or had ambiguous boundaries with other medical personnel. There was a significant correlation between compliance to the job description of the night shift and job satisfaction (rs=.43, p=.01). These results imply that it is necessary to establish strategies that will enhance work efficiency based on job analysis by shift work, reduce handover time using EMR system, stmart devices, and clarify appropriate performers.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.17 no.1
• /
• pp.71-75
• /
• 2013

Purpose: Currently, decrement revision using LDCT is used in PET/CT. But cold artifacts are often found in decrement revision image by mismatch between LDCT image and Emission image near diaphragm due to patient's respiration. This research studied reduction of cold artifact by patient's respiration using CTAC Shift among revision methods. Materials and Methods: From March to September in 2012, 30 patients who had cold artifacts by respiration were targeted using PET/CT Discovery 600 (GE Healthcare, MI, USA) equipment. Patients with cold artifacts were additionally scan in diaphragm area, and the image shown cold artifacts at whole body test were revised using CTAC Shift. Cold artifacts including image, additional scan image and CTAC Shift revision image were evaluated as 1~5 points with naked eye by one nuclear medicine expert, 4 radiotechnologists with over 5 year experience. Also, standard uptake value of 3 images was compared using paired t-test. Results: Additional scan image and CTAC Shift revision image received relatively higher score in naked eye evaluation than cold artifacts including image. The additional scan image and CTAC Shift revision image had high correlation as the results of ANOVA test of standard uptake value and did not show significant difference. Conclusion: When cold artifacts are appeared by patient's respiration at PET/CT, it causes not only patient inconvenience but troubles in test schedule due to extra radiation exposure and time consumption by additional scan. But if CTAC Shift revision image can be acquired with out additional scan, it is considered to be helped in exact diagnosis without unnecessary extra radiation exposure and additional scan.

• Safety and Health at Work
• /
• v.12 no.3
• /
• pp.390-395
• /
• 2021

Background: Health-care providers typically undergo shift work and are subjected to increased stress. Night shift work may induce disturbed sleep cycles and circadian rhythm. The objective of this study was to explore if night shift workers (NSWs) show an increased risk of abnormal thyroid-stimulating hormone (TSH). Methods: We conducted a retrospective cohort study of 574 employees without thyroid disease and abnormal TSH at baseline who underwent annual check-ups between 2007 and 2016 in a medical center. NSWs were defined as those with working time schedules other than daytime hours. We calculated the incidence rate and estimated the adjusted hazard ratio (HR) for incident abnormal TSH and subclinical hypothyroidism compared with non-NSWs using a Cox regression model. Results: A total of 56 incident abnormal TSH cases and 39 subclinical hypothyroidism cases in NSWs were identified during 3000 person-years of follow-up. In models adjusted for age, sex, obesity, and working departments, we found no increased relative risk for incident abnormal TSH (HR: 0.72, 95% confidence interval: 0.33-1.60) or subclinical hypothyroidism (HR: 0.52, 95% confidence interval: 0.19-1.45) when comparing NSWs to non-NSWs; nor were incidence rates significantly different among exclusively medical employees after excluding administrative staff. Conclusion: In this hospital-based nine-year follow-up retrospective cohort study, NSWs were not associated with increased relative risk of incident abnormal TSH and subclinical hypothyroidism, in contrast to previous cross-sectional studies.