• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.114-120
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• 2000

EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication Him is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing of internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the bearing performance of connecting rod big end On internal combustion engine.

• Tribology and Lubricants
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• 제17권3호
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• pp.228-235
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• 2001

EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication film is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing in internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the connecting rod bearing performance in internal combustion engine.

• 한국수산과학회지
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• 제47권2호
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• pp.154-159
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• 2014

The increasing of atmospheric $CO_2$ are changing the pH (ocean acidification) and temperature of the sea. Although the effects of ocean acidification on calcifying organisms have well-documented, only a few studies have examined the combined effects of ocean acidification and elevated temperature. This study investigated the effects of ocean acidification and elevated temperature for 2100 on survival and growth of juvenile abalone, Haliotis discus hannai. Ocean acidification was simulated by bubbling $CO_2$ into seawater at concentrations of 1,000 and 1,500 ppm, and temperature was set at room temperature $+2^{\circ}C$. Neither $CO_2$ nor temperature had a significant effect on survival of abalone, while both significantly affected growth. There was no significant interaction between the two factors. Shell length can be used as a growth index of abalone to access the impacts of ocean acidification and elevated temperature.

• 대한기계학회논문집
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• 제19권2호
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• pp.313-321
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• 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.

• 한국수산과학회지
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• 제51권1호
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• pp.107-112
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• 2018

One-dimensional numerical model is implemented to investigate temperature variations in the mixed layer depth (MLD) with the passage of typhoons. In the model, we assume a non-divergent, infinite ocean and consider wind effects only, excluding isostatic effects (inverse barometric effects) and upwelling with vertical movement of the water column. Numerical experiments investigate the effects of typhoon tracks on temperature variations, including their dependence on vertical resolutions in the MLD and these results are compared with those in a three-dimensional primitive equation model (POM). The model reproduces features of the observed temperature variations in the MLD fairly well, and implies that wind effects, rather than isostatic effects, play a predominant role in temporal and spatial temperature variations in the MLD. After the passage of typhoons, however, the model does not reproduce well the temperature variations observed in the MLD, because a limitation of the model is its inability to reproduce events such as cyclonic eddy formation (Hong et al., 2011; Masuda and Hong, 2011). The model also shows well the so called 'rightward bias' (Price, 1981) of sea surface cooling which is the most predominant in the right hand side of typhoon's track.

• Structural Engineering and Mechanics
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• 제47권6호
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• pp.839-856
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• 2013

Metallic annular discs with their outer boundary fully constrained are studied with newly derived semi-analytical solutions for the effects of thickness variations under thermal loading and unloading. The plane stress and axisymmetric assumptions were adopted, and the thickness of the disk depends on the radius hyperbolically with an exponent n. Furthermore, it is assumed that the stress state is two dimensional and temperature is uniform in the domain. The solutions include the elastic, elastic-plastic and plastic-collapse behavior, depending on the values of temperature. The von Mises type yield criterion is adopted in this work. The material properties, Young's modulus, yield stress and thermal expansion coefficient, are assumed temperature dependent, while the Poisson's ratio is assumed to be temperature independent. It is found that for any n values, if the normalized hole radius a greater than 0.6, the normalized temperature difference between the elastically reversible temperature and plastic collapse temperature is a monotonically decreasing function of inner radius. For small holes, the n values have strong effects on the normalized temperature difference. Furthermore, it is shown that thickness variations may have stronger effects on the strain distributions when temperature-dependent material properties are considered.

• 아시안잔디학회지
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• 제17권4호
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• pp.165-172
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• 2003

본 연구는 녹지의 배치와 식재형태가 기온저감효과에 미치는 영향을 파악한 결과 다음과 같은 점이 밝혀졌다. 1) 녹지의 기온분포도로부터 고온역은 주변시 가지에서, 저온역은 각 녹지내의 식재지주변과 소하천주변에서 확인되었다. 2) 녹지의 배치와 기온과의 관계를 보면, 저온역은 각 녹지와 거의 일치하고 녹지간 시가지 및 풍하쪽에도 저온역이 형성되었다. 3) 녹지간 시가지와 기온과의 관계를 보면 저온역은 풍하쪽 시가지뿐 아니라 녹지간 시가지에서도 나타났다. 또한, 풍상쪽에 녹지가 존재하지 않은 경우에도 녹지간 시가지는 주변 시가지 보다 낮은 기온이었다. 4) 토지피복비율과 기온에서 식재지, 초지 및 수면이 증가하면 모두 기온저감에 효과적이고, 나지의 증가는 기온상승에 효과적이다. 5) 교목, 소교목의 순으로 그 그루의 증가는 기온저감에 유효하게 관련되어 있는 것이 파악되었다.

• Journal of Forest and Environmental Science
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• 제34권3호
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• pp.246-248
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• 2018

Urban development and population have augmented the increase of impervious land-cover. This phenomenon has amplified the effects of climate change and increasing urban island effects due to increases in urban temperatures. Seoul, South Korea is one of the largest metropolitan cities in the world. While land uses in Seoul vary, land cover patterns have not changed much (under 2%) in the past 10 years, making the city a prime target for studying the effects of land cover types on the urban temperature. This research seeks to generalize the urban temperature of Seoul through a series of statistical tests using multi-temporal remote sensing data focusing on multiple scales and typologies of green space to determine its overall effectiveness in reducing the urban heat. The distribution of LST values was reduced as the size of urban forests increased. It means that changing temperature of large-scale green-spaces is less influenced because the broad distribution could be resulted in various external variables such as slope aspect, topographic height and density of planting areas, while small-scale urban forests are more affected from that. The large-scale green spaces contributed significantly to lowering urban temperature by showing a similar mean LST value. Both of concentration and dispersal of urban forests affected the reduction of urban temperature. Therefore, the findings of this research support that creating urban forests in an urban region could reduce urban temperature regardless of the scale.

• Journal of the Optical Society of Korea
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• 제12권4호
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• pp.288-297
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• 2008

Recent research efforts on study of silicon photonics utilizing stimulated Raman scattering have largely overlooked temperature effects. In this paper, we incorporated the temperature dependences into the key parameters governing wave propagation in silicon waveguides with Raman gain and investigated how the temperature affects the solution of the coupled-mode equations. We then carried out, as one particular application example, a numerical analysis of the performance of wavelength converters based on stimulated Raman scattering at temperatures ranging from 298 K to 500 K. The analysis predicted, among other things, that the wavelength conversion efficiency could decrease by as much as 12 dB at 500 K in comparison to that at the room temperature. These results indicate that it is necessary to take a careful account of temperature effects in designing, fabricating, and operating Raman silicon photonic devices.

• 정신신체의학
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• 제5권2호
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• pp.195-204
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• 1997

Objectives : The behavioral and physiological effects following low doses and high doses of melatonin have not been fully explored. In this study the authors investigated the nature and extent of the hypnotic effects, oral temperature, blood pressure effects, performance effects and subjective feelings following the acute administration of low pharmacological oral doses of melatonin at mid-day. Methods : Thirty-five healthy young medical students were randomly assigned to receive 6mg of oral melatonin(N=11), 12mg of oral melatonin(N=12) or a placebo(N=12) in a double-blind, placebo controlled trial. Measures of the behavioral and physiological effects used in the study were Stanford Sleepiness Scale, Digit Symbol Substitution Test, Trail test and visual analogue scale for subjective feelings. Oral temperature and blood pressure were measured. The subjects were studied between 10:00 and 16:00 hours. Data were analyzed by using repeated-measures analyses of variance(ANOVA). Results: Melatonin produced statistically significant effects on oral temperature, but there were no significant effects on time and the $dose{\times}time$ interaction. There was a significant difference on oral temperature between the 12mg oral melatonin group and the placebo group at 12:00 and 16:00 hours, but no significant difference between the 12mg and the 6mg oral melatonin groups. Melatonin produced a dose-related increase in subjective sleepiness and had significant effects on time, the $dose{\times}time$ interaction. There was a significant difference on subjective sleepiness among the placebo, 6mg, 12mg oral melatonin groups at 13:00-16:00 hours. Melatonin did not produce statistically significant dose-related effects on subjective fatigue but produced significant effects on time and the $dose{\times}time$ interaction. There was a significant difference on subjective fatigue between the 12mg, the 6mg oral melatonin groups and the placebo group at 13:00 hour. Conclusions : These data indicated that acute administration of melatonin at mid-day increased subjective sleepiness and fatigue but decreased oral temperatures. These effects were shown especially in 12mg oral melatonin group.