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Low Temperature Test of HWR Cryomodule
Heetae Kim,Youngkwon Kim,Min Ki Lee,Gunn-Tae Park,Wookang Kim 한국진공학회(ASCT) 2016 Applied Science and Convergence Technology Vol.25 No.3
Low temperature test for half-wave resonator (HWR) cryomodule is performed at the superfluid helium temperature of 2 K. The effective temperature is defined for non-uniform temperature distribution. Helium leak detection techniques are introduced for cryogenic system. Experimental set up is shown to make the low temperature test for the HWR cryomodule. The cooldown procedure of the HWR cryomodule is shown from room temperature to 2 K. The cryomodules is precooled with liquid nitrogen and then liquid helium is supplied to the helium reservoirs and cavities. The pressure of cavity and chamber are monitored as a function of time. The vacuum pressure of the cryomodule is not increased at 2 K, which shows leak-tight in the superfluid helium environment. Static heat load is also measured for the cryomodule at 2.5 K.
Temperature Measurement Techniques for RAON Cryomodule
Heetae Kim,Yoochul Jung,Yong Woo Jo,Min Ki Lee,Jong Wan Choi,Youngkwon Kim,Juwan Kim,Won-Gi Paeng,Moo Sang Kim,Hoechun Jung,Young Kwan Kwon 한국진공학회(ASCT) 2018 Applied Science and Convergence Technology Vol.27 No.2
Conducting and semiconducting temperature sensors are calibrated and applied to cryomodules. The definition of temperature is introduced and the pressure in vacuum is shown as a function of temperature. The resistance of Drude model is shown as a function of carrier density and mean free path. Temperature sensors are calibrated with Physical Property Measurement System (PPMS). The temperature sensors are applied to measure temperature accurately in RAON cryomodules.
In-Depth Study of Mold Heat Transfer for the High Speed Continuous Casting Process
Heetae Jeong,Jong-Yeon Hwang,Jung-Wook Cho 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2
Mold heat transfer during the commercial high speed continuous casting up to 7 m/min was investigated in order to clarify the influence of various operating conditions such as casting speed, mold flux, mold thickness, thickness and height of mold coated layer and so on. A simple, but practical formula of heat flux has been derived in terms of those operating conditions by analyzing the heat flux data obtained in CEM ® (Compact Endless Casting and Rolling Mill) caster based on simplified one dimensional heat transfer model. Especially, impact of mold parameters such as mold thickness, mold coated layer thickness and its height on the heat flux can be linearly expressed in the empirical formula derived. Heat flux ratio (HR), the ratio of the narrow face heat flux to the wide face one, is one of the important indicators to evaluate whether the solidified shell is evenly robust or not. Averaged HR in CEM ® caster is around 0.87, which varies according to the caster specifications and operating conditions. It is suggested that the mold taper should be adjusted to maintain the HR as close to 0.87 as possible.
HeeTae Kim,SangJib Kwon 한국교육개발원 2021 KEDI Journal of Educational Policy Vol.18 No.2
This study analyzes factors that influence the continuance intention of mobile learning (m-learning) for its users. We collected 222 responses from an online survey in South Korea. We conducted an empirical analysis by integrating the technology acceptance model and psychological factors related to learning. Subsequently, we verified the hypotheses drawn in this study using confirmatory factor analysis and structural equation modelling. The results show that perceived enjoyment, connectedness, and security, respectively, had a positive effect on the perceived ease of use and perceived usefulness of learning for users. Additionally, the results showed that perceived usefulness could be improved by increasing the perceived ease of use, which had a positive influence on learning satisfaction, learning self-efficacy, and continuance intention of m-learning, which were crucial to users’ learning outcomes. Particularly, learning self-efficacy, which was positively influenced by learners’ learning satisfaction, was also expected to boost the use of m-learning by influencing the continuance intention of m-learning. This study provided critical clues for expanding related research, and hence, this study has important implications for academic and practical purposes.
NOSTALGIA, ATTITUDE TOWARD SPONSORS, AND PURCHASE INTENTION FOR SPONSORS’ PRODUCTS
Heetae Cho,Weisheng Chiu,Hyun-Woo Lee,Xiaofang Doreen Tan 글로벌지식마케팅경영학회 2020 Global Marketing Conference Vol.2020 No.11
This study attempted to investigate how satellite fans’ nostalgia influences their attitude toward the European Professional Football Leagues (EPFL) sponsors and purchase intention toward EFL sponsors’ products. Based on the sample drawn from EPFL fans in Singapore, a conceptual model was developed. This study found that satellite fans’ nostalgia significantly affected attitude toward EPFL sponsors, which positively influenced their intention to purchase EPFL sponsors’ products. The findings of this study emphasize the critical role of sport nostalgia in affecting attitude and purchase intention and offer practical implications for marketers.