• Title/Summary/Keyword: Work pressure

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Thermal stress and Flow Analysis of a Cryogenic Ball Valve (초저온 볼밸브의 열 응력 및 유동해석)

  • Bae, S.K.;Lee, W.H.;Kim, H.S.;Kim, D.S.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.4
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    • pp.8-13
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    • 2006
  • The high pressure cryogenic ball valve is used to transfer the liquefied natural gas which temperature is $-196^{\circ}C$, supplied pressure is $168kgf/cm^2$. In the present work, the temperature distribution and thermal deformation is calculated numerically. The CAR and CFD methods are useful to predict the thermal matter and the inner flow field of high pressure cryogenic ball valve. For this reason, to optimum design of the cryogenic ball valve, the theological behavior of the supplied LNG in a cryogenic valve has been studied. The governing equations are discredited and solved numerically by the finite-volume method and finite-element method. In this study, we designed the high pressure cryogenic ball valve that accomplishes zero leakage by elastic seal at normal temperature and metal seal at high temperature.

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Cool gas and star formation properties of ram pressure stripped galaxy NGC 4522: Insights from the TIGRESS simulation

  • Choi, Woorak;Lee, Bumhyun;Chung, Aeree;Kim, Chang-Goo
    • The Bulletin of The Korean Astronomical Society
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    • v.44 no.1
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    • pp.77.2-77.2
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    • 2019
  • NGC 4522 is one of the best-known examples among the Virgo galaxies undergoing active ram pressure stripping. There have been a number of detailed observational and theoretical studies on this galaxy to constrain its stripping and star formation history. However, the impact of ram pressure on the multi-phased ISM, in particular molecular gas which plays an important role in star formation, is still not fully understood. NGC 4522, as a system where the extra-planar molecular gas is identified, is an ideal case to probe in depth how ram pressure affects molecular gas properties. Aiming to get more theoretical insights on the detailed stripping process of multi-phased ISM and its consequences, we have conducted simulations using the TIGRESS which could reproduce the realistic ISM under comparable conditions as NGC 4522. In this work, we compare the fraction of gas mass to stellar mass, star formation rates and gas depletion time scales of NGC 4522 with those measured from the simulations, not only inside the disk but also in the extra-planar space.

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Novel Design of Ultrashort Pulse Excimer Laser Amplifier System II (Temporal Gain Control and Phase Distortion/ASE Characteristics)

  • Lee, Young-Woo
    • Journal of information and communication convergence engineering
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    • v.1 no.4
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    • pp.228-232
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    • 2003
  • The previous design work for very large final amplifier pumped by electron beam module was described from the point of view of energy characteristics. In this work, the design problems for phase front distortion, ASE, and gain control in large aperture amplifier are presented in detail.

Measurement of CO Q-branch Raman Spectrum by using High Resolution Inverse Raman Spectrometer (고분해능 Inverse 라만 분광기를 이용한 CO Q-branch 라만 분광 측정)

  • 한재원
    • Proceedings of the Optical Society of Korea Conference
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    • 1989.02a
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    • pp.59-64
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    • 1989
  • Raman vibrational Q0branch spectra of pure CO are measured by using the technique of quasicw inverse Raman spectroscopy utilizing a pulsed single-frequency laser source. This approach gives enhanced sensitivity compared to earlier work which employed CW lasers, allowing extension of that work to higher accuracy, higher J states, and higher pressure. Fitting laws with pertubation theory and modified energy gap(MEG) theory are described, and the line broadening and shifting coefficients of J=0 to 24 are determined with both fitting laws.

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Association between Job-related Factors and Metabolic Syndrome among Male and Female Workers: Using the Korean National Health and Nutrition Examination Survey (남녀 근로자의 직업 관련 특성과 대사증후군 - 국민건강영양조사 자료를 이용하여 -)

  • Do, Kyung-A;Jung, Hye-Sun;Choi, Eun-Hi
    • Korean Journal of Occupational Health Nursing
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    • v.24 no.1
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    • pp.39-47
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    • 2015
  • Purpose: This study is performed to help manage the metabolic syndrome in work place by identifying the effect on metabolic syndrome with subjects of Korean adult workers. Methods: Using part of data of "The Fourth Korean National Health and Nutrition Examination survey 2nd year (2008)" which center for disease control is investigating. The general characteristics include age, educational level, occupation and marital status as factors affecting the metabolic syndrome of workers in this study. Results: Work-related factors are the working environment in which they are working while they are pressed for time due to work status and overload. If the work status of worker is unpaid family member, the risk is increased by more than twice compared to paid workers. The risk for metabolic syndrome in work environment to work while fighting the clock is decreased compared to the work environment without time pressure. Conclusion: In order to manage the metabolic syndrome of workers, health promotion program to change management of both working condition and working environment can contribute to prevent the metabolic syndrome and ultimately prevent the cerebrocardiovascular diseases.

The Use of Noise Dampening Mats to Reduce Heavy-Equipment Noise Exposures in Construction

  • Saleh, Sabah;Woskie, Susan;Bello, Anila
    • Safety and Health at Work
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    • v.8 no.2
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    • pp.226-230
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    • 2017
  • The performance of sound barriers was evaluated to determine their technical effectiveness and practicality in reducing noise exposures to operating engineers in construction. Commercially purchased sound dampening mats (SDMats) were installed inside three heavy-equipment engine compartments. Sound pressure levels (SPLs) were measured before and after installing the SDMats while the equipment was on idle and full-throttle settings where it normally operates. SPLs inside the heavy-equipment operator cabs were significantly reduced by 5.6-7.6 dBA on the full-throttle setting following installation of the SDMats (p < 0.01). The evaluated engineering control intervention was simple to install, affordable, and substantially reduced the engine noise reaching the heavy-equipment operator, potentially reducing reliance on hearing-protection devices to protect construction workers from noise exposures.

An Experimental Study on the Characteristics of Attenuation and Propagation of Pilings Noise by SIP Method in Construction Field (SIP공법에 의한 항타소음의 전달 및 감쇠특성에 관한 실험적 연구)

  • 이병윤;김병주;박재영;김재수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.10a
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    • pp.227-236
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    • 1997
  • Construction equipment noise has caused much annoyance for a number of dwellers in nearby construction field and has become a very serious issue in our living environment. Therefore, in our country, a practical solution and a better method of reducing construction equipment noise are highly required in construction field. Practical solutions for the construction equipment noise, however, are very difficult because the poorness of basic data and insufficiency of the existing research. Especially, in order to establishment of sound insulation plan about pilings work noise that has highly sound pressure level and impactive, a real situation of sound characteristics about pilings work noise in foundation work demands close investigation. In this point, this study attempts to surveys the characteristics of attenuation and propagation of construction equipment noise in pilings work using SIP(soilcement injected precast pile) method. And this study intends to get the basic data for establishment of a standard about construction noise.

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Influence of clamped-clamped boundary conditions on the mechanical stress, strain and deformation analyses of cylindrical sport equipment

  • Yuhao Yang;Mohammad Arefi
    • Geomechanics and Engineering
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    • v.35 no.5
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    • pp.465-473
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    • 2023
  • The higher order shear deformable model and an exact analytical method is used for analytical bending analysis of a cylindrical shell subjected to mechanical loads, in this work. The shell is modelled using sinusoidal bivariate shear strain theory, and the static governing equations are derived using changes in virtual work. The eigenvalue-eigenvector method is used to exactly solve the governing equations for a constrained cylindrical shell The proposed kinematic relation decomposes the radial displacement into bending, shearing and stretching functions. The main advantage of the method presented in this work is the study of the effect of clamping constraints on the local stresses at the ends. Stress, strain, and deformation analysis of shells through thickness and length.

The Relationship Between High School Teachers Health Perception and Health Promotion Behavior (고등학교 교사의 건강지각과 건강증진행위의 관계)

  • Kim, Dong-Hwan;Park, Young-Soo
    • The Journal of Korean Society for School & Community Health Education
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    • v.4
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    • pp.21-41
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    • 2003
  • The purposes of this study were to ; first, investigate High School Teachers health promotion behavior types; second, explore the effects High School Teachers perceived benefits and perceived barriers have on their health promotion behavior ; third, suggest a desirable course that will increase teachers health. To this end, this researcher conducted a survey on health promotion behavior, perceived benefits, and perceived barriers to 329 High School teachers working in Goyang-si, Gyonggi-do. The results of the survey are as follows: Health Promotion Behavior A closer look at high school teachers health promotion behavior shows that male teachers, compared with female teachers, more actively promote their health. However, female teachers are more aware of their personal hygiene and disease risks. Older teachers, rather than younger teachers, are more willing to promote their health through better eating habits and more frequent exercise. A comparison between married and single teachers revealed that married teachers promote their health through better eating habits, and single teachers receive less stress and are better at managing their stress. Teachers working in technical high schools are better at managing their stress and personal hygiene than academic high schools teachers. Teachers working after 8 o'clock show better health promotion behavior through proper eating habits, stress management, regular exercise, disease prevention: however, teachers working before 7:30 are poor at managing their stress. Teachers not teaching supplementary lessons and not supervising night self-study are better at managing their stress, exercise schedule, and disease prevention than teachers who are. Perceived Benefits, Perceived Barriers, and Health Promotion Behavior A Comparison between male and female teachers shows that female teachers firmly believe improved eating habits and regular exercises would greatly enhance their health. However, female teachers felt more discomfort in their working environment and in utilizing medical institutes. Teachers in the 20s and 40s perceived health benefits through regular lifestyle and exercise. Teachers with less experience feel more pressure from their work environment. Teachers below their 30s feel more dissatisfaction towards using medical facilities. Teachers working in Technical High Schools are more aware of promoting their health through regular health checkups, exercise, and lifestyle ; however, teachers from Academic High Schools feel more pressure from their work environment. Teachers not performing supplementary lessons and supervising night self-study sessions are more willing to go through regular health checkups than those performing them. Also, teachers with supplementary lessons and night self-study supervisions claimed lack of leisure time, pressure from work environment, and inconvenience in using medical facilities a deterrent to promoting their health behavior. The Relationship between Health Promotion Behavior, Perceived Benefits, and Perceived Barriers The correlation ratio between Health Promotion Behavior and Perceived Benefits shows a positive relationship. The results show that High School teachers believed regular health checkups are necessary in maintaining their health. This research shows that teachers consider the following factors important in the order shown ; regular lifestyle and exercise, prevention of geriatric diseases, improving ones eating habits. In short, teachers who are more aware of the importance of regular health checkups are also more aware of the importance of promoting their health. The correlation ratio between Health Promotion Behavior and Perceived Barriers shows negative relationship. High School Teachers believe that lack of leisure activity, pressure from work environment, familys financial burden, fear of diseases, inconvenience in using medical facilities are a deterrent in promoting their health behavior. In other words, teachers with less leisure time and negative pressures from their work environment were less active in promoting their health behavior. This study shows that High School teachers will be able to promote their health behavior by maintaining regular health checkups, lifestyle, exercise, and preventing geriatric diseases. However, teachers believed that insufficient leisure time and negative pressure from their work environment acted as a deterrent to maintaining their health behavior. Most High School teachers believe they are at present healthy, and they were actively engaged in Preventative Health Promotion. The result of this study demonstrates that External factors have a large impact on teachers, which in turn acts negatively on their Health Promotion Behavior. In order to guarantee teachers health promotion behavior, systematic health checkups and increased leisure time, improvement in their work environment are necessary. Teachers also need to take a more active interest in their health.

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Atmospheric Pressure Micro Plasma Sources

  • Brown, Ian
    • Journal of Surface Science and Engineering
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    • v.34 no.5
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    • pp.384-390
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    • 2001
  • The hollow cathode discharge is a kind of plasma formation scheme in which plasma is formed inside a hollow structure, the cathode, with current to a nearby anode of arbitrary shape. In this scheme, electrons reflex radially within the hollow cathode, establishing an efficient ionization mechanism for gas within the cavity. An existence condition for the hollow cathode effect is that the electron mean-free-path for ionization is of the order of the cavity radius. Thus the size of this kind of plasma source must decrease as the gas pressure is increased. In fact, the hollow cathode effect can occur even at atmospheric pressure for cathode diameters of order 10-100 $\mu\textrm{m}$. That is, the "natural" operating pressure regime for a "micro hollow cathode discharge" is atmospheric pressure. This kind of plasma source has been the subject of increasing research activity in recent years. A number of geometric variants have been explored, and operational requirements and typical plasma parameters have been determined. Large arrays of individual tiny sources can be used to form large-area, atmospheric-pressure plasma sources. The simplicity of the method and the capability of operation without the need for the usual vacuum system and its associated limitations, provide a highly attractive option for new approaches to many different kinds of plasma applications, including plasma surface modification technologies. Here we review the background work that has been carried out in this new research field.

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