http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
곽영실,양태용,길효섭,Devulapalli Venkata Phanikumar,허복행,이재진,황정아,최승환,박영덕,최호성 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.1
We present preliminary observations of the field-aligned-irregularities (FAIs) in the E and F regions during the solarminimum (2009 - 2010) using the 40.8 MHz coherent backscatter radar at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude)in South Korea. The radar, which consists of 24 Yagi antennas, observes the FAIs using a single beam with a peak power of24 kW. The radar has been continuously operated since December 2009. Depending on the manner of occurrence of thebackscatter echoes, the E-region echoes are largely divided into two types: quasi-periodic (QP) and continuous echoes. Our observations show that the QP echoes occur frequently above an altitude of 105 km in the post-sunset period andcontinuous echoes occur preferentially around an altitude of 105 km in the post-sunrise period. QP echoes appear asstriated discrete echoes for a period of about 10 - 20 min. The QP-type echoes occur more frequently than the continuoustypeechoes do and the echo intensity of the QP type is stronger than that of the continuous type. In the F region, the FAIsoccur at night at an altitude interval of 250 - 450 km. As time proceeds, the occurrence height of the FAIs gradually increasesuntil early in the morning and then decreases. The duration of the F-region FAIs is typically a few hours at night, although,in rare cases, FAIs persist throughout the night or appear even after sunrise. We discuss the similarities and differences ofthe FAIs observed by the Daejeon radar in comparison with other radar observations.
Kwak, Young-Sil,Yang, Tae-Yong,Kil, Hoysub,Phanikumar, Devulapalli Venkata,Heo, Bok-Haeng,Lee, Jae-Jin,Hwang, Junga,Choi, Seong-Hwan,Park, Young-Deuk,Choi, Ho-Seong 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.1
We present preliminary observations of the field-aligned-irregularities (FAIs) in the E and F regions during the solar minimum (2009 - 2010) using the 40.8 MHz coherent backscatter radar at Daejeon (36.18ºN, 127.14ºE, 26.7ºN dip latitude) in South Korea. The radar, which consists of 24 Yagi antennas, observes the FAIs using a single beam with a peak power of 24 kW. The radar has been continuously operated since December 2009. Depending on the manner of occurrence of the backscatter echoes, the E-region echoes are largely divided into two types: quasi-periodic (QP) and continuous echoes. Our observations show that the QP echoes occur frequently above an altitude of 105 km in the post-sunset period and continuous echoes occur preferentially around an altitude of 105 km in the post-sunrise period. QP echoes appear as striated discrete echoes for a period of about 10 - 20 min. The QP-type echoes occur more frequently than the continuoustype echoes do and the echo intensity of the QP type is stronger than that of the continuous type. In the F region, the FAIs occur at night at an altitude interval of 250 - 450 km. As time proceeds, the occurrence height of the FAIs gradually increases until early in the morning and then decreases. The duration of the F-region FAIs is typically a few hours at night, although, in rare cases, FAIs persist throughout the night or appear even after sunrise. We discuss the similarities and differences of the FAIs observed by the Daejeon radar in comparison with other radar observations.
Piyush Kumar,Reliance Jain,M. R. Rahul,Abhijit Ghosh,Sumanta Samal,Gandham Phanikumar 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.9
The present study explores the high temperature deformation behavior of FeCoNiCrAlTi dual phase high entropy alloy(henceforth referred to as DP-HEA) in the temperature range of 900–1100 °C (1173–1373 K) and the strain rate varyingfrom 0.001 to 0.1 s−1. The as-cast sample has been characterized using scanning electron microscopy, X-ray diffraction,and differential scanning calorimetry, which reveals the presence of two phases, disordered γ and ordered γ′. A constitutiverelationship between the process parameters (stress temperature, strain, and strain rate) has been drawn using the Arrheniustypeequation to recognize the high temperature deformation behavior of the DP-HEA. The optimum thermomechanicalprocessing window of the DP-HEA has been determined by constructing multiple contour maps based on different parameterssuch as efficiency, strain rate sensitivity, etc. And the optimum processing domain has been found to lie approximately in thetemperature range of 1260–1300 K and SR = 10–2.3–10–2 s−1, 1325–1373 K and SR = 10–1.4–10–1 s−1 & 1173–1193 K andSR = 10–1.3–10–1.55 s−1. Finally, the stable and unstable regimes in the processing maps are correlated with the microstructureof hot deformed samples.