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The Effects of Perceived Interactivity on Intention of Continuous Use of Smartwatches
Junsub Yi 한국인터넷전자상거래학회 2018 인터넷전자상거래연구 Vol.18 No.5
The study aims to offer empirically tested findings of users’ trust in smartwatches in the context of IoT. The study (1) analyzes the causal relationship between perceived interactivity of a smartwatch and intention of continuous use, (2) examines cognitive and affective trust perceptions as the underlying mechanisms for mediating this relationship, (3) investigates affective trust as a resulting variable of cognitive trust. The result of analysis implies that not only direct effects but also indirect effects are significant in a series of causal relationships from perceived interactivity to intention of continuous use through cognitive and affective trusts. The analysis result also indicates that cognitive and affective trusts play key roles as mediators between perceived interactivity and intention of continuous use. In addition, the analysis result shows that cognitive trust affects affective trust.
Lee, Junsub,Koh, Kyungmi,Kim, Young-Eui,Ahn, Jin-Hyun,Kim, Sunyoung Society for General Microbiology 2013 The Journal of general virology Vol.94 No.7
<P>NF-E2 related factor 2 (Nrf2) is a transcription factor that plays a key role(s) in cellular defence against oxidative stress. In this study, we showed that the expression of Nrf2 was upregulated in primary human foreskin fibroblasts (HFFs), following human cytomegalovirus (HCMV/HHV-5) infection. The expression of haem oxygenase-1, a downstream target of Nrf2, was also increased by HCMV infection, and this induction was suppressed in HFFs expressing a small hairpin RNA (shRNA) against Nrf2. The HCMV-mediated increase in Nrf2 expression was abolished when UV-irradiated virus was used or when the activity of casein kinase 2 was inhibited. Host cells infected by HCMV had higher survival rates following oxidative stress induced by buthionine sulfoximine compared with uninfected control cells, but this cell-protective effect was abolished by the use of Nrf2 shRNA. Our results suggest that HCMV-mediated activation of Nrf2 might be beneficial to the virus by increasing the host cell’s ability to cope with oxidative stress resulting from viral infection and/or inflammation.</P>
최준섭(Junsub Choi),문태석(Taeseok Moon),최종인(Jongin Choi),박상현(Sanghyeon Park),김한솔(Hansol Kim),허환일(Hwanil Huh) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.8
고도보정 노즐은 모든 고도에서 최적의 성능을 발휘할 수 있도록 고안된 노즐이다. 발사체의 비추력을 향상시키기 위한 방법으로는 연소실만의 특성인 특성배기속도를 향상시키는 방법과 노즐만의 특성인 추력계수를 향상시키는 방법이 있다. 고도보정 노즐은 동일한 연소기에서 노즐의 성능 개선을 통해 발사체의 성능향상을 가능하게 한다. 고도보정 노즐에 대한 연구는 독일 DLR에서 활발하게 진행되고 있으며, 미국, 러시아, 영국, 호주, 일본 등 항공우주선진국에서도 진행되고 있다. 본 논문에서는 고도보정 노즐에 대한 기술 현황 및 특허 동향에 대해 조사하였다. 이를 바탕으로 고도보정 노즐의 기술흐름을 파악하고 발사체 성능향상 연구에 기초자료로 활용하고자 한다. The altitude compensation nozzle is a nozzle designed for optimum performance at all altitudes. A method of improving the specific impulse of the space launch vehicle is a method of improving the characteristic exhaust velocity which is a characteristic of the combustion chamber and a method of improving the thrust coefficient which is a characteristic of the nozzle. The altitude compensation nozzle enables improvement of the performance of the space launch vehicle by improving the nozzle performance for the same combustor. Research on altitude compensation nozzles has been actively carried out in the DLR in Germany and is being carried out in advanced countries such as the US, Russia, UK, Australia and Japan. In this paper, the technology trends and patent trends of altitude compensation nozzles are investigated and summarized. Based on this, the technical trends of altitude compensation nozzles is grasped and utilized as basic data for the study on the performance improvement of a launch vehicle.
노즐 목 외부형 핀틀추력기의 추력특성에 대한 수치해석 연구
최준섭(Junsub Choi),김동연(Dongyeon Kim),허환일(Hwanil Huh) 한국항공우주학회 2015 韓國航空宇宙學會誌 Vol.43 No.12
외부형 핀틀추력기의 핀틀 행정거리, 고도, 보어유무가 핀틀추력기 성능에 미치는 영향에 대해서 전산수치해석을 수행하였다. 유동은 핀틀 행정거리에 관계없이 항상 과소팽창하는 결과를 보였다. 핀틀추력기의 주요 성능 지표 중 추력조절측면에서는 우수한 성능을 보였지만, 핀틀 지지대 윗면에서 발생한 충격파로 인해 공력하중이 증가하였다. 지상에서 고도 20 km로 상승하면 노즐 출구 속도, 마하수, 추력 등이 증가하였으며, 공력하중 또한 증가하였다. 보어의 존재는 공력하중을 5.9% 증가시켜 핀틀의 구동력을 위해서는 보어가 없는 형상이 유리하다고 판단된다. Numerical computations were performed to investigate the effects of pintle stroke, altitude, and bore on the performance of an external pintle thruster. Results show that under-expansion flow occurs always, independent of pintle stroke. An external pintle thruster shows good performance in that it is capable of good amount of thrust control, while aerodynamic loads are increased due to shock waves on the pintle support. When altitude is increased to 20 km, the nozzle exit velocity, Mach number, thrust as well as aerodynamic loads are increased. Bore increases aerodynamic load 5.9%, and therefore pintle shape without bore is preferred for lower aerodynamic load of a pintle in order to actuate the pintle.
최준섭(Junsub Choi),황희성(Heuiseong Hwang),허환일(Hwanil Huh) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.5
E-D 노즐은 배기가스의 압력과 외부압력의 상호작용을 통해 고도를 보정하는 노즐이다. E-D 노즐과 관련하여 미국의 TRW에서 특허를 등록하였고, 호주, 영국, 독일 등에서 수치해석 및 실험적 연구가 진행 중이다. 본 논문에서는 E-D 노즐에 대한 국외 기술을 분석하였고, 이를 바탕으로 E-D 노즐 설계 및 수치해석을 수행하였다. 그 결과 노즐 압력비가 증가함에 따라 추력성능이 증가하는 것을 확인하였다. E-D nozzle is an altitude compensation nozzle through the interaction between the nozzle exhaust pressure and the atmosphere pressure. E-D nozzle patent is registered by the TRW of the United States and numerical/experimental studies is conducted by the Australia, the United Kingdom, and Germany. In this paper, the technology regarding E-D nozzle is analyzed and both the E-D nozzle design and numerical study are carried out. As a result, it is confirmed that the more nozzle pressure ratio increase, the more thrust performance increase.