• Title/Summary/Keyword: Rotating shift

Search Result 71, Processing Time 0.026 seconds

Field Study of Effects of Night Shifts on Cognitive Performance, Salivary Melatonin, and Sleep

  • Kazemi, Reza;Motamedzade, Majid;Golmohammadi, Rostam;Mokarami, Hamidreza;Hemmatjo, Rasoul;Heidarimoghadam, Rashid
    • Safety and Health at Work
    • /
    • v.9 no.2
    • /
    • pp.203-209
    • /
    • 2018
  • Background: Night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue. This study set out to measure cognitive performance, melatonin rhythms, and sleep after different consecutive night shifts (7 vs. 4) among control room operators (CORs). Methods: The participants included 60 CORs with a mean age of 30.2 years (standard deviation, 2.0) from a petrochemical complex located in Southern Iran. Cognitive performance was assessed using the n-back task and continuous performance test. To evaluate melatonin, saliva was collected and tested by enzyme-linked immunosorbent assay. To assess sleep and sleepiness, the Pittsburgh Sleep Quality Index and Karolinska Sleepiness Scale were used, respectively. Results: Individuals who worked 7 consecutive night shifts had a significantly better cognitive performance and sleep quality than those who worked 4 consecutive night shifts. However, salivary melatonin profile and sleepiness trend were not affected by shift type. Conclusion: The main duty of CORs working night shifts at the studied industry included managing safety-critical processes through complex displays; a responsibility that demands good cognitive performance and alertness. It is suggested that an appropriate number of consecutive night shifts in a rotating shift system should be planned with the ultimate aim of improving CROs performance/alertness and enhancing safety.

Pattern recognition by shift control of input pattern (입력 영상의 쉬프트 컨트롤에 의한 패턴인식)

  • Kang, M.S.;Cho, D.S.;Kim, B.C.
    • Proceedings of the KIEE Conference
    • /
    • 1992.07a
    • /
    • pp.459-461
    • /
    • 1992
  • This paper presents the new method to recognize the 2D patterns dynamically by rotating the input patterns according to the difference vector. Generally neural network with many patterns leads to various recognition ratio. The dynamic management of input patterns means that we can move pixels to desired locations controlled by the difference vector. We divide dual neural network model into two parts at learning phase, respectively. And then we combine them to construct the total network. Our model has some good results such that it has less number of patterns and reduced learning time. At present, we only discuss the four way movement of input patterns. The research for the complex movement will be fulfilled later.

  • PDF

A Study on the Torsional Vibration Measurement of the Horizontal Shaft with Disks (단을 가진 수평축의 비틀림진동 측정에 관한 연구)

  • 박일수;안찬우;김중완
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1997.04a
    • /
    • pp.3-8
    • /
    • 1997
  • This parer was presented for the experimental results of torsional vibrations of the horizontal rotating shaft with three disks. The torsional vibrations meter used is a laser system for non-contact measurement of torsional angular vibration velocity and torsional angular vibration displacement. The distance between the disks war changed; the one that had 76mm of disk distance war called basic model, and another that had 106mm of disk distance wide model, and other that had 46mm of disk distance narrow model. In each model, outer diameter of disk was 40mm. And 45mm, or 50mm was also used to extend the effective range of frequencies. The angula vibration displacement and the angular vibration velocity in its torsional vibration were measured to obtain the stable and the unstable regions.

  • PDF

An Experimental Study on the Measurement of Radial Directional Natural Frequency in a Passenger Car Tire Roboting under the Load (하중을 받고 회전하는 승용차 타이어의 반경방향 고규진동수 측정에 관한 실험적 연구)

  • Kim, Byoung-Sam;Hong, Dong-Pyo;Chi, Chang-Heon
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.20 no.1
    • /
    • pp.1-13
    • /
    • 1996
  • The measurement of radial directional natural frequency ina passenger car tire rotating under the load is studied. In order to obtain theoretical matural frequency and mode shape, the ploane vibration of a tire is modeled to that of circular beam. By esing the Tieking method based on Hamiltons's principle, theoretical results are determined by considering tension horce due to tire inflation pressure, retational velocity and tangential, radial stiffness. Radial directional modal parameters varying with the inflation pressure, load, rotational velocity are experimentally determined by using frequency response function method. The results show that experimental conditions canbe considered as the parameters which shift the natural frequency.

Numerical Study of Wavy Taylor-Couette Flow(I) -Without an Axial Flow- (Wavy Taylor-Couette 유동에 대한 전산해석 (I) -축방향 유동이 없는 경우-)

  • Hwang, Jong-Yeon;Yang, Gyeong-Su
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.25 no.5
    • /
    • pp.697-704
    • /
    • 2001
  • The flow between two concentric cylinders, with the inner one rotating, is studied using numerical simulation. This study considers the identical flow geometry as in the experiments of Wereley and Lueptow[J. Fluid Mech., 364, 1998]. They carried out experiment using PIV to measure the velocity fields in a meridional plane of the annulus in detail. When Taylor number increases over the critical one, the flow instability caused by curved streamlines of the tangential flow induces Taylor vortices in the flow direction. As Taylor number further increases over another critical one, the steady Taylor vortices become unsteady and non-axisymmetrically wavy. The velocity vector fields obtained also show the same flow features found in the experiments of Wereley and Lueptow.

Optical Emission Anisotropy in InP Aligned Quantum Dots

  • Shin, Y.H.;Kim, Yongmin;Song, J.D.;Choi, Subong
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2014.02a
    • /
    • pp.288.2-288.2
    • /
    • 2014
  • InP quantum dots were grown by using the molecular beam epitaxy technique. Quantum dots are connected and composed string-like one-dimensional structure due to the strain field along [110] crystal direction. Two prominent photoluminescence transitions from normal quantum dots and string-like one-dimensional structure were observed which show strong optical anisotropy along [1-10] and [110] crystal directions. Both peaks also showed blue-shift while rotating emission polarization from [1-10] to [110] direction. Such optical transition behaviors are the consequence of the valence band mixing caused by strain field along the [110] crystal direction.

  • PDF

A Study on Hoslital Nurses' Preferred Duty Shift and Duty Hours (병원 간호사의 선호근무시간대에 관한 연구)

  • Lee, Gyeong-Sik;Jeong, Geum-Hui
    • The Korean Nurse
    • /
    • v.36 no.1
    • /
    • pp.77-96
    • /
    • 1997
  • The duty shifts of hospital nurses not only affect nurses' physical and mental health but also present various personnel management problems which often result in high turnover rates. In this context a study was carried out from October to November 1995 for a period of two months to find out the status of hospital nurses' duty shift patterns, and preferred duty hours and fixed duty shifts. The study population was 867 RNs working in five general hospitals located in Seoul and its vicinity. The questionnaire developed by the writer was used for data collection. The response rate was 85.9 percent or 745 returns. The SAS program was used for data analysis with the computation of frequencies, percentages and Chi square test. The findings of the study are as follows: 1. General characteristics of the study population: 56 percent of respondents was (25 years group and 76.5 percent were "single": the predominant proportion of respondents was junior nursing college graduates(92.2%) and have less than 5 years nursing experience in hospitals(65.5%). For their future working plan in nursing profession, nearly 50% responded as uncertain The reasons given for their career plan was predominantly 'personal growth and development' rather than financial reasons. 2. The interval for rotations of duty stations was found to be mostly irregular(56.4%) while others reported as weekly(16.1%), monthly(12.9%), and fixed terms(4.6%). 3. The main problems related to duty shifts particularly the evening and night duty nurses reported were "not enough time for the family, " "afraid of security problems after the work when returning home late at night." and "lack of leisure time". "problems in physical and physiological adjustment." "problems in family life." "lack of time for interactions with fellow nurses" etc. 4. The forty percent of respondents reported to have '1-2 times' of duty shift rotations while all others reported that '0 time'. '2-3 times'. 'more than 3 times' etc. which suggest the irregularity in duty shift rotations. 5. The majority(62.8%) of study population found to favor the rotating system of duty stations. The reasons for favoring the rotation system were: the opportunity for "learning new things and personal development." "better human relations are possible. "better understanding in various duty stations." "changes in monotonous routine job" etc. The proportion of those disfavor the rotating 'system was 34.7 percent. giving the reasons of"it impedes development of specialization." "poor job performances." "stress factors" etc. Furthermore. respondents made the following comments in relation to the rotation of duty stations: the nurses should be given the opportunity to participate in the. decision making process: personal interest and aptitudes should be considered: regular intervals for the rotations or it should be planned in advance. etc. 6. For the future career plan. the older. married group with longer nursing experiences appeared to think the nursing as their lifetime career more likely than the younger. single group with shorter nursing experiences ($x^2=61.19.{\;}p=.000;{\;}x^2=41.55.{\;}p=.000$). The reason given for their future career plan regardless of length of future service, was predominantly "personal growth and development" rather than financial reasons. For further analysis, the group those with the shorter career plan appeared to claim "financial reasons" for their future career more readily than the group who consider the nursing job as their lifetime career$(x^2$= 11.73, p=.003) did. This finding suggests the need for careful .considerations in personnel management of nursing administration particularly when dealing with the nurses' career development. The majority of respondents preferred the fixed day shift. However, further analysis of those preferred evening shift by age and civil status, "< 25 years group"(15.1%) and "single group"(13.2) were more likely to favor the fixed evening shift than > 25 years(6.4%) and married(4.8%)groups. This differences were statistically significant ($x^2=14.54, {\;}p=.000;{\;}x^2=8.75, {\;}p=.003$). 7. A great majority of respondents(86.9% or n=647) found to prefer the day shifts. When the four different types of duty shifts(Types A. B. C, D) were presented, 55.0 percent of total respondents preferred the A type or the existing one followed by D type(22.7%). B type(12.4%) and C type(8.2%). 8. When the condition of monetary incentives for the evening(20% of salary) and night shifts(40% of. salary) of the existing duty type was presented. again the day shift appeared to be the most preferred one although the rate was slightly lower(66.4% against 86.9%). In the case of evening shift, with the same incentive, the preference rates for evening and night shifts increased from 11.0 to 22.4 percent and from 0.5 to 3.0 percent respectively. When the age variable was controlled. < 25 yrs group showed higher rates(31.6%. 4.8%) than those of > 25 yrs group(15.5%. 1.3%) respectively preferring the evening and night shifts(p=.000). The civil status also seemed to operate on the preferences of the duty shifts as the single group showed lower rate(69.0%) for day duty against 83. 6% of the married group. and higher rates for evening and night duties(27.2%. 15.1%) respectively against those of the married group(3.8%. 1.8%) while a higher proportion of the married group(83. 6%) preferred the day duties than the single group(69.0%). These differences were found to be statistically all significant(p=.001). 9. The findings on preferences of three different types of fixed duty hours namely, B, C. and D(with additional monetary incentives) are as follows in order of preference: B type(12hrs a day, 3days a wk): day shift(64.1%), evening shift(26.1%). night shift(6.5%) C type(12hrs a day. 4days a wk) : evening shift(49.2%). day shift(32.8%), night shift(11.5%) D type(10hrs a day. 4days a wk): showed the similar trend as B type. The findings of higher preferences on the evening and night duties when the incentives are given. as shown above, suggest the need for the introductions of different patterns of duty hours and incentive measures in order to overcome the difficulties in rostering the nursing duties. However, the interpretation of the above data, particularly the C type, needs cautions as the total number of respondents is very small(n=61). It requires further in-depth study. In conclusion. it seemed to suggest that the patterns of nurses duty hours and shifts in the most hospitals in the country have neither been tried for different duty types nor been flexible. The stereotype rostering system of three shifts and insensitiveness for personal life aspect of nurses seemed to be prevailing. This study seems to support that irregular and frequent rotations of duty shifts may be contributing factors for most nurses' maladjustment problems in physical and mental health. personal and family life which eventually may result in high turnover rates. In order to overcome the increasing problems in personnel management of hospital nurses particularly in rostering of evening and night duty shifts, which may related to eventual high turnover rates, the findings of this study strongly suggest the need for an introduction of new rostering systems including fixed duties and appropriate incentive measures for evenings and nights which the most nurses want to avoid, In considering the nursing care of inpatients is the round-the clock business. the practice of the nursing duty shift system is inevitable. In this context, based on the findings of this study. the following are recommended: 1. The further in-depth studies on duty shifts and hours need to be undertaken for the development of appropriate and effective rostering systems for hospital nurses. 2. An introduction of appropriate incentive measures for evening and night duty shifts along with organizational considerations such as the trials for preferred duty time bands, duty hours, and fixed duty shifts should be considered if good quality of care for the patients be maintained for the round the clock. This may require an initiation of systematic research and development activities in the field of hospital nursing administration as a part of permanent system in the hospital. 3. Planned and regular intervals, orientation and training, and professional and personal growth should be considered for the rotation of different duty stations or units. 4. In considering the higher degree of preferences in the duty type of "10hours a day, 4days a week" shown in this study, it would be worthwhile to undertake the R&D type studies in large hospital settings.

  • PDF

Factors associated with the dietary quality and nutrition status using the Nutrition Quotient for adults focusing on workers in the manufacturing industry (영양지수를 이용한 제조업 근로자의 영양상태 평가 및 관련 요인 연구)

  • Yim, Ji Suk;Heo, Young Ran
    • Journal of Nutrition and Health
    • /
    • v.53 no.5
    • /
    • pp.488-502
    • /
    • 2020
  • Purpose: This study examined the factors influencing Nutrition Quotient for adults (NQ-A), focusing on workers in the manufacturing industry. Methods: The participants were 738 industrial workers in Gwangju. Their dietary information was analyzed using a questionnaire of NQ-A, which consisted of 21 checklist items and the general characteristics of the subjects. The scores of NQ-A and its 4 factors (balance, moderation, diversity, and dietary behavior) were calculated according to the general characteristics of subjects. The data were analyzed using a χ2 test, t-test, correlation, and multiple regression using SPSS 21.0 program. Results: The mean NQ-A score was 45.3 for the total subjects, indicating a low grade. Non-shift workers showed significantly higher scores for balance, diversity, and moderation factors than shift workers. Forty-three (8.7%) shift workers and 123 (50.8%) non-shift workers had good NQ-A scores, whereas 453 (91.3%) shift workers and 119 (49.2%) non-shift workers required monitoring for nutrition. The significant influencing factors of NQ-A were the working pattern (p < 0.001), gender (p < 0.001), family composition (p < 0.001), age (p < 0.001), and household income (p < 0.001). As a result of multiple regression analysis, there was a significant difference in the NQ-A score for moderation (F = 141.930, p < 0.001), diversity (F = 98.998, p < 0.001), balance (F = 52.329, p < 0.001), and dietary behavior (F = 12.895, p < 0.001). As a result, shift work and gender had the greatest influence on the balance (β = -0.372, p < 0.001), diversity (β = -0.316, p < 0.001), and moderation (β = -0.507, p < 0.001) factors in NQ-A. Gender had the most influence on the dietary behavior in NQ-A. Conclusion: Shift work and gender were significant factors affecting NQ-A. To manage workers' health better, it will be necessary to prepare a nutrition education program according to the type of working pattern and gender.

A Numerical study of the fluctuation behavior of the oxygen concentration and the temperature in the silicon melt of Czochralski crystal growth system

  • Yi, Kyung-Woo;Kim, Min-Cheol
    • Proceedings of the Korea Association of Crystal Growth Conference
    • /
    • 1997.06a
    • /
    • pp.197-201
    • /
    • 1997
  • The momentum, heat and mass trasfer phenomena in the silicon melt of the Czochralki crystal growth system are calculated using a three dimensional numerical simulation thechnique. Even though axisymmetrical boundary conditions are imposed to all calculations in a 3cm diameter crucible, several types of non-axisymmetric profiles of velocities, temperature and oxygen concentration appeared in the melt. Because of the non-axisymmetric profiles of velocities, temperature and oxygen concentration appeared in the melt. Because of the non-axisymmetric profiles and rotations of fluid induced by the crucible rotation, temperatures and oxygen concentrations in the silicon melt fluctuate. The rotating velocity of the profile is calculated from the phase shift of the data of temperature or oxygen at two different points which have same radius from center but 90 degree angular difference. From this calculation, it is found that the rotating veolocity of the oxygen and temperature is different from the crucible rotation rates. Therefore the frequencies of the oscillating temperature and oxygen concentrations are not same to the frequencies of the crucible rotations. Futhermore, the components of the frequencies of the temperature and oxygen concentration at the same point are not same. The fluctuation behaviors of the temperature or oxygen themselves are also different when the points are different. The calculation show that the temperature and the oxygen concentration near the interface also fluctuate. The results suggest that the striation pattern found in the grown silicon single crystals may ben generated by the oxygen concentration and the temperature oscillations of the melt occurred near the interface.

  • PDF

Positioning-error Analysis of Vibration Sensors for Prognostics and Health Management in Rotating System (갠트리 크레인 호이스트의 건전성 평가를 위한 진동 모사시스템 구축과 데이터 통계 분석)

  • Jang, Jaewon;Han, Zhiqiang;Zhang, Haiyang;Oh, Daekyun
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.28 no.2
    • /
    • pp.346-353
    • /
    • 2022
  • Recently, studies on the integrity of rotating machines, such as gantry cranes, which are used in the shipbuilding industry, have been actively conducted. Gantry cranes are driven at relatively low revolutions per minute (RPM), are frequently operated and stopped, and are impacted by external environmental factors, such as shock and noise in the measurement data. The purpose of this study was to construct a replica of a gantry crane hoist used in indoor shipbuilding and analyze the acquired data for errors caused by the shift in operating conditions (RPM) and the change in the position of the data acquisition sensor. Consequently, we observed that the error caused by differences in sensor positions did not occur significantly under low operating conditions but occurred significantly under relatively high operating conditions. Thus, we determined that both the operating condition and position of the acquisition sensor affected the data acquired by the rotary machine.