• Bulletin of the Korean Chemical Society
• /
• v.19 no.3
• /
• pp.295-299
• /
• 1998

HSP104 protein in Saccharomyces cerevisiae is known to provide thermotolerance when induced by various kinds of stresses, such as a mild heat shock, ethanol, and hypoxia. It helps cells survive at an otherwise lethal temperature. Mechanisms by which HSP104 protein works are yet to be elucidated. In order to understand a molecular basis of thermotolerance due to HSP104 protein induced by a mild heat shock, studies on respiratory pathways were carried out in the wild type as well as in the hsp104 deleted mutant. Especially the degree of 13C-acetate incorporation into glutamate-C4 was examined for both strains using 13C-13C homonuclear spin coupling measurements, since glutamate is in a rapid equilibrium with α-ketoglutarate in the TCA cycle. In addition, the temperature effects on the rate of 13C incorporation are compared with or without HSP104 protein expressed. Finally, the inhibitory effect of HSP104 on the respiration pathway was confirmed by the measurements of oxygen consumption rates for both strains.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.6
• /
• pp.1582-1589
• /
• 1994

The characteristics Prandt1-Meyer expansion of supersonic flow with condensation through a wavy wall in a channel are investigated by experiment and numerical direct marching method of characteristics. In the present study, for the case of moist air flow in the type of indraft supersonic wind tunnel, the dependency of location of formation and reflection of the oblique shock wave generated by the wavy wall and the distribution of flow properties, on the specific humidity and temperature at the entrance of wavy wall and the attack angle of the wavy wall to the main stream is clarified by schlieren photograph, distribution of static pressure and Mach number, and plots of numerical results. Also, we confirm that the wavy wall plays an important key role in the formation of oblique shock wave, and that the effect of condensation on the flow field appears apparently.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.627-632
• /
• 2002

The paper considers acoustic analysis of the shock absorbing muffler within a rotary compressor. The internal space of the compressor is modelled as a combination of cavities and pipes. A simple one-dimensional impedance approach is used fur the acoustic analysis in the low frequency range, with ignoring the effects of gas flow and temperature gradients that are closely related to power efficiency of the compressor. Using the similarity between the vibration isolator and the shock absorbing muffler, the source strength transmissibility is newly proposed as a performance measure of the muffler and its validity is supported by power analysis. Some Important muffler design rules obtained are; (1) a muffler cavity and its opening throat should be used as a pair, (2) a long thin throat is desirable for high frequency noise isolation, (3) a large muffler cavity should be used with care since it shortens the working frequency range of the muffler. The rules were applied to redesign a compressor muffler currently in use, and a significant improvement was achieved by simply attaching a throat to the outlet holes of the muffler.

• Nuclear Engineering and Technology
• /
• v.33 no.2
• /
• pp.132-144
• /
• 2001

Fracture mechanics is one of the major areas of the pressurized thermal shock (PTS) evaluation. To evaluate the reactor pressure vessel integrity associated with PTS, PFM methodology demands precise calculation of temperature, stress, and stress intensity factor for the variety of PTS transients. However, the existence of stainless steel cladding, with different thermal, physical, and mechanical property, at the inner surface of reactor pressure vessel complicates the fracture mechanics analysis. In this paper, treatment schemes to evaluate stress and resulting stress intensity factor for RPV with stainless steel clad are introduced. For a reference transient, the effects of clad thermal conductivity and thermal expansion coefficients on deterministic fracture mechanics analysis are examined.

• The Korean Journal of Zoology
• /
• v.35 no.2
• /
• pp.203-210
• /
• 1992

Hsp70, a 70 kDa protein, is the maior protein expressed when cells are heat-shocked. A cDNA library from mouse ID13 cells was screened with the human hsp70 gene as a probe, and a positive clone was obtained. The positive clone was subcloned into puc19 and the precise restriction was obtained. The CDNA was sequenced by the Sanger's dideoxv termination method. Single open reading frame that codes for a protein of 70 kDa was found. The DNA sequence of the cloned mouse DNA shows great homology (66-90%) with other mouse hsp70 genes and somewhat less homology (50",) with E. coli hsp70 gene (dnak). With the exception of one amino acid, the protein sequence deduced from the CDNA is identical to the mouse that shock cognate protein 70 (hsc70) that is constitutivelv expressed at normal temperature. The result suggests that the cloned CDNA encodes a hsc70 family rather than a heatinducible family.mily.

• Journal of Drive and Control
• /
• v.15 no.3
• /
• pp.36-42
• /
• 2018

Agricultural tractors require frequent shifting to improve operation efficiency, and PST (Powershift Transmission) is considered as a suitable transmission. However, due to the inherent characteristics of the PST, shocks arise during shifting, which imparts a negative effect on the operator. Therefore, in order to improve the transmission performance of the tractor PST, researches on various methods including the hydraulic system circuit, the engine input speed control, and the mechanical system of the transmission are steadily being conducted. In this study, in order to reduce the impact of PST on a shift based on SimulationX software, we analyzed the characteristics of the input signal of PCV (Pressure Control Valve) through sensitivity analysis and verified the simulation model through actual vehicle test. Optimization was performed for minimizing the shift shock for some of the parameters of the input signal at constant temperature and RPM conditions.

• Journal of the Korean Society of Safety
• /
• v.18 no.4
• /
• pp.39-43
• /
• 2003

An experimental study was conducted to develop and understanding of fracture behavior of ceramic thermal barrier coating when subjected to a thermal shock loading. The thermal loading was applied using a 1.5kW $CO_2$ laser. In the experiments, beam-shaped specimens were subjected to a high heat flux for 4sec and cooling of 7sec in air. The interface crack length was increased as the crack density, the surface pre-crack legth and the coating thickness were increased. The center surface crack length was increased as the maximum surface temperature got higher and the surface pre-crack length for shorter.

• Steel and Composite Structures
• /
• v.25 no.2
• /
• pp.187-196
• /
• 2017

In this work, transient thermo-piezo-elastic responses of an infinite functionally graded piezoelectric (FGPE) plate whose upper surface suffers time-dependent thermal shock are investigated in the context of different thermo-piezo-elastic theories. The thermal and mechanical properties of functionally graded piezoelectric plate under consideration are expressed as power functions of plate thickness variable. The solution of problem is obtained by solving the corresponding finite element governing equations in time domain directly. Transient thermo-piezo-elastic responses of the FGPE plate, including temperature, stress, displacement, electric intensity and electric potential are presented graphically and analyzed carefully to show multi-field coupling behaviors between them. In addition, the effects of functionally graded parameters on transient thermo-piezo-elastic responses are also investigated to provide a theoretical basis for the application of the FGPE materials.

• The Bulletin of The Korean Astronomical Society
• /
• v.45 no.1
• /
• pp.55.2-55.2
• /
• 2020

Radio relics in the outskirts of galaxy clusters are interpreted as synchrotron radiation due to the relativistic electrons produced via diffusive shock acceleration (DSA) in shocks with low sonic Mach numbers, Ms ≤ 3 in high beta ICM plasma. Electron injection into the DSA process at such weak shocks is one of the key elements, which has yet to be fully understood. In this study, we explore the nature of kinetic microinstabilities excited in weak quasi-perpendicular shocks through 2D particle-in-cell simulations. We find Alfven-ion cyclotron (AIC), whistler, and mirror instabilities can be triggered by ion and electron temperature anisotropy in the immediate downstream of supercritical shocks with Ms > Mcrit ~ 2.3. In particular, AIC instability causes rippling of the shock surface, which in turn generates plasma waves on multi-scales and faciliates the electron preacceleration. Our results may contribute to understanding the origins of radio relics.

• Asian-Australasian Journal of Animal Sciences
• /
• v.21 no.8
• /
• pp.1116-1126
• /
• 2008

The objective of this study was to investigate the expression and localization of heat shock protein 70 (Hsp70) and its mRNA in the heart, liver, and kidney of acutely heat-stressed broilers at various stressing times. Male AA broilers (n = 100) were randomly divided into 5 groups of 20 birds per group. After 30 d of adaptive feeding at ambient temperature, 80 experimental broilers were suddenly heat stressed by increasing the environmental temperature from $22{\pm}1^{\circ}C$ to $37{\pm}1^{\circ}C$. The 4 groups were heat stressed for 2, 3, 5, and 10 h, respectively. The localizations of Hsp70 protein and mRNA, determined by immunohistochemical staining and in situ hybridization, respectively, were demonstrated to be tissue dependent, implying that different tissues have differential sensibilities to heat stress. Intense Hsp70 staining was identified in the vascular endothelial cell of heart, liver and kidney, suggesting an association between expression of Hsp70 in vascular endothelial cell and functional recovery of blood vessels after heat shock treatment. Ante-mortem heat stress had a significant effect on the expression of Hsp70 protein and mRNA. The quantitation of Hsp70 protein and mRNA were both time and tissue dependent. During the exposure to heat stress, the heart, liver and kidney of broiler chickens exhibited increased amounts of Hsp70 protein and mRNA. The expression of hsp70 mRNA in the heart, liver and kidney of heat-stressed broilers increased significantly and attained the highest level after a 2-h exposure to elevated temperatures. However, significant elevations in Hsp70 protein occurred after 2, 5, and 3 h of heat stressing, respectively, indicating that the stress-induced responses vary among different tissues.