• Korean Journal of Medicinal Crop Science
• /
• v.9 no.4
• /
• pp.265-268
• /
• 2001

This experiment was conducted to investigate the effects of temperature, light, seed harvesting time, storage temperature, and period on its germination of Astragalus membranaceus. Optimum germination temperature was ${20{\sim}25^{\circ}C}$ and it was found to be light insensitive seed. The germination rates were not significantly different between 1-year and 2-year old plants, and seed harvesting times. Seeds stored at such cold temperatures as ${-4^{\circ}C\;and\;-20^{\circ}C}$ for 15 months showed over 80% in germination rate at the 6th day after placement. On the other hand, low germination rate of 60% at the 11th day was observed from the seeds stored at $4^{\circ}$ and room temperature.

• Journal of Mechanical Science and Technology
• /
• v.16 no.8
• /
• pp.1064-1071
• /
• 2002

Stainless steel pipe of type 304 the with a wall thickness of 26.9 mm and the outer diameter 406.4 mm is welded by manual arc welding process. Mechanical properties and fracture toughness of type 304 stainless steel are investigated in the temperature ranging from room temperature to -162$^{\circ}C$ The results obtained are summarized as follows. The tensile strength noticeably increases as the temperature becomes lower while the yield strength is relatively insensitive to temperature. The Charpy impact energy and CTOD values become higher in the case that crack propagation direction is aligned to the transverse axis upon the rolling direction than longitudinal direction. The drop of fracture toughness is associated with the noticeable diminution of plastic component as temperature seduces from room temperature to -162$^{\circ}C$ .

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.1
• /
• pp.131-140
• /
• 1993

The activation energy for high temperature creep is associated with stresses, temperatures, straians And the creep strain appears to be a function of a temperature, compensated time, namely $te^{-}$.DELTA.H/RT/, and the stress. In fact this functional relation appears to be isomorphic to material structure by x-ray analyses. Applying this functional relation, the dependance of activation energy for A17075 creep was investigated. The activation energy for creep is insensitive to stress, temperature, structure, and strain. And phenomenological model agrees with experimental creep data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.10a
• /
• pp.375-378
• /
• 2013

A reference voltage generator which is insensitive to PVT (process-voltage-temperature) variation necessary for NVM memory IPs such as EEPROM and MTP memories is designed in this paper. The designed BGR (bandgap reference voltage) circuit based on MagnaChip's $0.18{\mu}m$ EEPROM process uses a low-voltage bandgap reference voltage generator of cascode current-mirror type with a wide swing and shows a reference voltage characteristic insensitive to PVT variation. The minimum operating voltage is 1.43V and the VREF sensitivity against VDD variation is 0.064mV/V. Also, the VREF sensitivity against temperature variation is $20.5ppm/^{\circ}C$. The VREF voltage has a mean of 1.181V and its three sigma ($3{\sigma}$) value is 71.7mV.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.24 no.2
• /
• pp.199-204
• /
• 2000

This study was conducted to investigate the thermoregulatory responses and wearing behavior of the cold-sensitive men when exposed to the mild cold of 14$^{\circ}C$. Two sessions of experiment were carried out and five healthy young men for the cold-sensitive group(CSG) and four healthy young for the cold-insensitive group(CIG) participated in the study as subjects CSG maintained rectal temperature lower than CIG due to their thicker clothing resulted in larger decrease of rectal temperature. CSG maintained skin temperatures higher than CIG. CSG felt cooler than CIG but wore thicker clothing for thermal comfort and this made keep their sensation warmer. These results were discussed in terms of autonomic and behavioral temperature regulation.

• Journal of the Optical Society of Korea
• /
• v.17 no.4
• /
• pp.300-304
• /
• 2013

Novel breakthrough random-hole optical fibers (RHOFs) are fabricated in a draw tower facility, by tapering an optical fiber preform packed with a silica powder mixture capable of producing air holes in situ at the high temperature of tens of hundreds in degrees Celsius. Structural and propagation characteristics of the porous RHOF are explained briefly. Experimental investigations of the invented RHOF are performed for pressure sensor applications. Remarkable results are obtained for the RHOF with desirable pressure sensitivity independent of temperature, as is required for harsh conditions as in oil reservoirs.

• Structural Engineering and Mechanics
• /
• v.43 no.6
• /
• pp.725-737
• /
• 2012

The temperature on steel structures is larger than the ambient air temperature under solar radiation and the temperature distribution on the affected structure is non-uniform and complicated. The steel tube, as a main structural member, has been investigated through experiment and numerical analysis. In this study, the temperature distribution on a properly designed steel tube under solar radiation is measured. A finite element transient thermal analysis method is presented and verified by the experimental results and a series of parametric studies are carried out to investigate the influence of various geometric properties and orientation on the temperature distribution. Furthermore, a simplified approach is proposed to predict the temperature distribution of steel tube. Based on both the experimental and the numerical results, it is concluded that the solar radiation has a significant effect on the temperature distribution of steel tubes. Under the solar radiation, the temperature of steel tubes is about $20.6^{\circ}C$ higher than the ambient air temperature. The temperature distribution of steel tubes is sensitive to the steel solar radiation absorption, steel tube diameter and orientation, but insensitive to the solar radiation reflectance and thickness of steel tube.

• Proceedings of the KIEE Conference
• /
• 1998.07e
• /
• pp.1837-1839
• /
• 1998

This paper proposes the strain-insensitive temperature sensing in quasi-distributed sensor system using different thermal expension coefficient materials. This system has the high sensitivity and hasn't the necessity of reference signal. We can monitor the condition of the power cable with this system.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.5
• /
• pp.632-639
• /
• 2014

Mechanical stress and the vacuum level are the two main factors dominating the quality factor of a resonator operated in the vacuum range 1 mTorr to 10 Torr. This means that if the quality factor of a resonator is very insensitive to the mechanical stress in the vacuum range, it is sensitive to mainly the ambient vacuum level. In this paper, a wafer-level packaged MEMS resonator with a highly vacuum-sensitive quality factor is presented. The proposed device is characterized by a package with out-of-plane symmetry and a suspending structure with only a single anchor. Out-of-plane symmetry helps prevent deformation of the packaged device due to thermal mismatch, and a single-clamped structure facilitates constraint-free displacement. As a result, the proposed device is very insensitive to mechanical stress and is sensitive to mainly the ambient vacuum level. The average quality factors of the devices packaged under pressures of 50, 100, and 200 mTorr were 4987, 3415, and 2127, respectively. The results demonstrated the high controllability of the quality factor by vacuum adjustment. The mechanical robustness of the quality factor was confirmed by comparing the quality factors before and after high-temperature storage. Furthermore, through more than 50 days of monitoring, the stability of the quality factor was also certified.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.352-358
• /
• 2011

This paper describes on the study of mitigation technique in which a pyrosensor is automatically sensing the rate of risk of fire or explosion of solid rocket motor exposed to an unexpected fire and makes the rocket motor burn itself safely. SCO test was carried out with a rocket motor loaded with HTPB propellant, in which a thermal pyrosensor igniter was installed. The rocket motor in SCO test was located in an oven at $50^{\circ}C$ for 7 hours. The temperature was regulated to be elevated at the rate of $3.3^{\circ}C$ per hour. Results showed Type V(Burning) reaction in this SCO test.