• Tribology and Lubricants
• /
• 제9권1호
• /
• pp.22-31
• /
• 1993

The thermohydrodynamic performance of large tilting pad journal bearings is analyzed, taking into account the three dimensional variation of lubricant viscosity. The eddy viscosity model based on wall formula is applied. The effects of temperature rise and turbulence on the bearing performance are studied in comparision with the isothermal or the laminar analysis. It is shown that these effects have significant influence on temperature distribution, load capacity and power loss of the bearing.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2008년도 하계학술발표대회 논문집
• /
• pp.1285-1290
• /
• 2008

The interest in use of new field of energy and unused existing potential energy has been raised in number of advanced countries including South Korea. As a respond of the interest and the following reactions, a new technology which helps to reduce bad environmental factors and decrease national energy consumption rate in the way of extract cold-heat energy in dam water. This research focuses on a method that enables taking the water flows in desirable temperature range whilst keeping water temperature boundaries of bottom level water. The analysis was made in simulating on CFD. In order to keep the temperature boundary level, a deep well pump was set in piping in the simulation. As the significant result, the most alteration in temperature was found when the smallest size of pipe was plumbed. However, when the flow has small value of velocity, no matter how big the piping size was, the temperature variation was negligible. Therefore, possible hypothesis was made as bigger piping as fast flow will have better function in the way to keep the temperature boundary level.

• Nuclear Engineering and Technology
• /
• 제56권9호
• /
• pp.3668-3685
• /
• 2024

The operation of a nuclear power plant relies on precalculated nuclear design predictions based on core calculations of various reactor states. The fuel temperature is a crucial factor in determining the reactor fuel behavior, but assessing the temperature variation in a fuel pellet taking into account neutron transport is challenging. Detailed simulation of the temperature behavior within the fuel pellet can be obtained by coupling of Monte Carlo neutron transport codes with thermal-hydraulics solvers. However, this approach is not practical for standard nuclear design calculations, and computationally cheaper and faster methods must be used. In nuclear core simulators, a concept of a single "effective temperature" that yields the same neutron response as in the case of the actual temperature shape is mainly applied. This paper evaluates various fuel temperature models used in nuclear core simulation calculations, ultimately recommending a new effective temperature model that considers the burnup correction.

• 대한간호학회지
• /
• 제5권2호
• /
• pp.38-50
• /
• 1975

This study was conducted to find the shortest optimum time for taking oral temperature and axillary temperature, which does not affect reliability of body temperature. For this purpose, first, the time at which all the samples are reaching maximum temperature is identified Second, the mean maximum temperature is compared with the mean temperature of each consecutive measurement by T-test to find the time at which no significant changes in temperature occurs along time sequence. Third, optimum temperatures are set at points of -0.2℉, -0.4℉, -0.6℉, -0.8℉, -1.0℉, -1.2℉, -1.4℉, from maximum temperature. A point of time at which 90% of samples reach at optimum temperature is identified and defined as optimum time. The study sample, a total of 164 cases were divided into two groups according to their measured body temperature. The group with body temperature below 37 $^{\circ}C$(A group) and above 37$^{\circ}$1'C (B group) were compared on the time required to reach maximum temperature and optimum temperature. The results are as follow. 1. The time required for total sample to reach maximum temperature was 13 minutes in both groups by oral method, 15 minutes in A group and 13 minutes in B group by axillary method. Time required for 90 % of cases reach maximum temperature by oral method was 10 minutes in both group. By axillary method, 12 minutes in A group. (Ref: table 2) 2. Statistical analysis by means of T-test, the time which does not show a significant change by oral method were 12 minutes in A group and 11 minutes in B group, and by axillary method 14 minutes in A group and 11 minutes in B group. (Ref: table 5, 6.) 3. Where optimum temperature was defined as maximum temperature minus 0.2 ℉, optimum time was found 8 minutes in both groups by oral method, and 11 minutes in A group and 9 minutes in B group by axillary method 4. Where optimum temperature was defined as maximum temperature minus 0.4 ℉, optimum time was found 7 minutes in A group and 6 minutes in B group by oral method, and 9 minutes in A group and 7 minutes in B group by axillary method 5. Where optimum temperature was defined as maximum temperature minus 0.8 ℉, optimum time was found 6 minutes in A group and 6 minutes in B group by axillary method (Ref: table 7, 8, 9, 10) 6. The commonly practiced temperature taking time, 3 minutes in oral method and 5 minutes in axillary method can be accepted as pertinent when physiological variation of body temperature at the mean level of -1, 2 ℉ is accepted. 7. The difference in time required to resister maximum temperature was compared between the group with body temperature below 37$^{\circ}C$ and above 37$^{\circ}$1'C, and found no significant difference in oral mettled and 1 - 4 minute difference in axillary method with shorter time requirement in feverish group.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
• /
• pp.355-356
• /
• 2002

The dielectric permittance and the dielectric loss factor of several lubricating oils were measured at frequencies from 100 Hz to 1.5 MHz. The measurements were carried out under atmospheric pressure as a function of temperature and under fixed temperature as a function of pressure. Temperature and pressure dependence of dielectric relaxation time were investigated. The temperature dependence of relaxation time obeyed the Vogel-Fulcher-Tammann (VFT) law. We modified the VFT equation in order to express the dielectric relaxation time as a function of temperature and pressure. Furthermore. by taking into consideration the similarity of the temperature and pressure dependence between dielectric relaxation and mechanical relaxation. the prediction of high-pressure viscosity were conducted. The predicted results were compared with the viscosity data obtained from the falling-sphere type viscometer.

• 대한가정학회지
• /
• 제20권2호
• /
• pp.65-71
• /
• 1982

Comfort concept of heating and cooling between body and environment is modified by the clothing. So were can say the clothing is one of the environment. To maintain“pleasantness”, clothing must have the elements of comfort and function. This study carried out for the 1st step to describe the relation between clothing and the human body I aspect to the emvironmental elements of temperature and working part of the body. Observations of skin temperature were taken on young adults female subjects in training wear and the skin temperature was measured onto 9 points of the body while taking part in two physical exercise, with Rawing machine and Bicycle ergometer. The results obtained are as follows; 1. The skin temperature after physical exercise is lower than that after repose. 2. After physical exercise of the lower part of the body, the skin temperature is less than that after physical exercise of the upper part of the body. 3. After physical exercise of the upper part of the body, skin temperature of the lower part of the body rises a little, and vice versa.

• 대한기계학회논문집
• /
• 제19권2호
• /
• pp.313-321
• /
• 1995

The effects of the temperature rise and the turbulence are very important factors to predict the accurate performance of a large tilting pad journal bearing. In this study, the dynamic characteristics of a large tilting pad journal bearing are analyzed, taking into account the three dimensional variation of lubricant viscosity and turbulence. The effects of the temperature rise and the turbulence on the stiffness and damping coefficients are investigated in comparison with the results from the laminar or isothermal theory. The stiffness and damping coefficients increase due to the turbulence but decrease due to the temperature rise. The results show that the effects of both the temperature rise and turbulence must be considered simultaneously in order to predict the dynamic characteristics of a large tilting pad journal bearing more accurately.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 춘계학술대회논문집A
• /
• pp.760-765
• /
• 2000

The study deals with the development of a computational procedure for evaluating the temperature rise in dry and lubricated multi-layered contacts of head/disk interface. A transient computational model with a transformed rectangular computational domain is utilized. A model and a computational method for micro-contact with sub-lubricated zone, including friction heat generation, have been presented. The model was applied, taking full account of the changes in contact area and contact load due to frictional heating. The computational distribution of temperature is obtained with the analytical findings for various composition and contact conditions. Especially, a rapid rise ($220^{\circ}C$ or above) in read head temperature lese to a saturation in the influence of a thermal spike on signal performance. This general class of problems can be treated provided that heat generation distribution and layer properties are known.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
• /
• pp.928-933
• /
• 1998

The temperature and stress behaviour of mass concrete pier at early ages was analysed based on the finite element method. The pier investigated is a three-dimensional structure of which the cross-sectional shape varies from a circle to an ellipsoid along the longitudinal axis. In order to obtain the transient temperature and stress distributions in the structure, a three dimensional method was adopted, because the structure of this type cannot be modeled accurately by a two-dimensional method. Temperature analysis was performed by taking into consideration of the cement type and content, boundary and environment conditions including the variations of atmospheric temperature and wind velocity. The results of this study may be useful for the temperature control to restrain thermal cracking and the construction management to design the resonable curing method of mass concrete structure.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.29-32
• /
• 2000

In this paper, an analytical model for I-V characteristics of a HEMTs is Proposed. The developed model takes into account the temperature dependence of drain current. In high-speed ICs for optical communication systems and mobile communication systems, temperature variation affects performance; for example the gain, efficiency in analog circuits and the delay time, power consumption and noise mrgin in digital circuits. To design such a circuit taking into account the temperature dependence of the current-voltage characteristic is indispensible. This model based on the analytical relation between surface carrier density and Fermi potential including temperature dependent coefficients.