• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.610-615
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• 2003

Electric rolling stock is one of major public transportation because of an increase in population and heavy traffic problems. The passengers under the influenced of indoor air quality such as air temperature, relative humidity and air velocity. Ventilation system on passenger cars should be designed for the health and comfort of the passengers. One of the main aim is to create an acceptable thermal environment without draught problems. The draught sensation increases when the air temperature decreases and the air velocity increases. Airflow in passenger cars is turbulent. Lateral temperature and humidity gradients in the electric rolling stock have been studied. And, the difference in the mean temperature and relative humidity measured at 0.7, 0.9, 1.2, 1.7 m above from the floor.

• 열처리공학회지
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• 제7권2호
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• pp.103-110
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• 1994

It is well-known that the analysis of temperature distribution is substantilly important in optimal design of quenching process. The unsteady state temperature gradients generated during the quenching process were numerically calculated by the Finite Element Method(F. E. M.). Formulations of F. E. M. based weighted residural method were presented for the analysis of the two dimensional heat conduction problem. In the process of calculation, the temperature dependency of physical properties of the material was in consideration. At early stage of the quenching process, the abrupt temperature gradient has been shown in the surface of the carbon steel(SM45C).

• Clinical and Experimental Reproductive Medicine
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• 제20권2호
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• pp.107-115
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• 1993

Procedures to separate motile. normal & motile and acrosome-reacted sperm with high efficiency have clinical application in Assisted Reproductive Technology in terms of increasing the probability of fertilization by a normal sperm and subsequent normal embryonic development. This study evaluated the effects of 10 sperm preparation techniques [Swim-up from a washed pellet (SU). Swim-up from semen (SO). Continuous Percoll Gradients I (PIC). Discontinuous Percoll Gradients I (PID). Continuous Percoll Gradients II(P II C). Discontinuous Percoll Gradients II(P II D), SpermPrep (SFC). Wang's tube (WT). Albumin Gradients (AG), Low temperature capacitation (LTC)] on motility (%), normal morphology (%), motile sperm recovery rate(%). morphologically normal & motile sperm recovery rate (%), true acrosome reaction (%) and fertilizing ability. A P II D proved to be an effective means of separating morphologically normal & motile sperm. Our results indicated the P II D has advantages as compared with other methods in terms of recovery rate. enhancement of motility and normal morphology. And a LTC seems to be an effective means of enhancing the true acrosome reaction and fertilizing ability. These results suggest that the combined method of LTC and P II D for separation of morphologically normal & motile sperm and acrosome reacted sperm may be a useful procedure for intrauterine insemination and in vitro fertilization in the management of male factor infertility as well as for isolation of subpopulation of sperm for basic research.

• Journal of Advanced Marine Engineering and Technology
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• 제38권2호
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• pp.208-216
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• 2014

In case of any coastal ocean near the mouth of huge rivers, low salinity water can be formed due to its large amount of freshwater discharge. For the acoustic analysis on the low salinity environment, some oceanographic data of the East China Sea and the Atlantic Ocean were collected through KODC (Korea Oceanographic Data Center) and NODC (National Oceanographic Data Center) online service. In this paper, the T-S gradient diagram is introduced to show a relation between the gradients of temperature and salinity in view of acoustic surface channel formation. Existence of haline channel, quantitative contribution of gradients of salinity and temperature, effectiveness of the channel formation can be known by the T-S gradient diagram. After applying the collected data into the diagram, tropical regions of the Atlantic Ocean show strong haline channel due to its nearly invariant temperature and drastic change of salinity with depth. The averaged transmission loss in the channel is about 5.7 ~ 7.5 dB less than that out of the channel by the results of acoustic propagation model (RAM: Range independent Acoustic Model). On the other hand, the East China Sea and temperate region of the Atlantic ocean have weaker haline channel with less difference of the averaged transmission loss between in and out of the channel as 3.2 ~ 6.0 dB. Although data samples used in this study have limitation to represent the general physical structures of the three ocean regions, the T-S gradient diagram is shown to be useful and acoustic field affected by low salinity environment is investigated in this study.

• Journal of Welding and Joining
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• 제32권4호
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• pp.1-9
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• 2014

A quantitative understanding on the effect of the welding conditions on weld joint dimensions and weld thermal cycle is difficult through experimental studies alone. The experimental realization of temperature distribution in the weld pool is proved to be extremely difficult due to the small size of welds, high peak temperature and steep temperature gradients in weld pool. This review deals with the heat transfer and fluid flow analysis to understand the parametric influence of a single wire submerged arc welding (SAW) and multi-wire SAW processes on the weld bead dimensions, temperature and fluid flow distribution in the weldment.

• Coupled systems mechanics
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• 제1권2호
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• pp.165-182
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• 2012

Macroscopic hot spots formed due to the large thermal gradients at the surface of the disc brake rotor, make the rotor to fail or wear out early. Thermo-elastic deformation results in contact concentration, leading to the non uniform distribution of temperature making the disc susceptible to hot spot formation. The formation of one hot spot event will predispose the system to future hot spotting at the same location. This leads to the complete thermo-elastic instability in the disc brakes; multitude parameters are responsible for the thermo elastic instability. The predominant factor is the sliding velocity and above a certain sliding velocity the instability of the brake system occurs and hot spots is formed in the surface of the disc brake. Commercial finite element package ABAQUS(R) is used to find the temperature distribution and the result is validated using Rowson's analytical model. A coupled analysis methodology is evolved for the automotive disc brake from the transient thermo-elastic contact analysis. Temperature variation is studied under different sliding speeds within the operation range.

• KSTLE International Journal
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• 제2권1호
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• pp.40-45
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• 2001

The paper deals with a non-linear finite element analysis of the thermomechanical distortions of an elastomeric O-ring seal including a temperature gradient. Axial compression of O-ring seals, as well as the influence of the temperature gradients and various O-ring seal models, are investigated based on the axisymmetric analysis. The highest temperature occurs near the interface of the O-ring between the dovetail groove bottom and the O-ring seal. The calculated FEM results indicate that the composite O-ring with the diametral ratio, 0.8 shows very stable and recommendable compared with other seal models far elevated temperatures and corrosive environments.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.409-412
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• 2006

Bulk metallic glass (BMG) strips of $Cu_{54}Ni_6Zr_{22}Ti_{18}$ were produced by warm rolling of the amorphous powder canned with copper. Controlling of temperatures of the rolled sample and rolls was essential for the successive rolling process. Because improper controlling of the sample temperature gave rise to the crystallization of BMG loading to the catastrophic fracture of BMG strips, the temperature of rolls should be properly controlled for achieving successful powder rolling of BMG. The variations of the strain state and temperature in the roll gap was simulated by the finite element method(FEM) using various roll temperatures.

• 천문학논총
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• 제8권1호
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• pp.199-206
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• 1993

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ${\sim}\;0.8\;keV$ and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.114-117
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• 2003

Conventional heating the heat source cause the molecules to react from the surface toward the center so that successive layers of molecules heat in turn. The product surfaces may be in danger of over heating by the time heat penetrates the material. Microwave, however, produce a volume heating effect. All molecules are set in action at the same time. It also evens temperature gradients and offers other important benefits such as selective heating. (omitted)