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Seung Ook Kim(김승욱),Jacqueline H. Chen,Chun Sang Yoo(유춘상) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.5
The characteristics of turbulent lifted non-premixed hydrogen jet flames under various coflow conditions have widely been investigated due to their relevance to practical applications. Three 3-D DNSs of turbulent lifted hydrogen/air jet flames in heated coflows near auto-ignition limit are performed to examine the stabilization mechanisms and flame structure of turbulent lifted jet flames.
Seung Ook Kim(김승욱),Minh Bau Loung,Chun Sang Yoo(유춘상) 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.2013 No.12
Two-dimensional direct numerical simulations (DNSs) of the ignition of lean primary reference fuel (PRF)/air mixtures at high pressure and intermediate temperature near negative temperature coefficient (NTC) regime were performed to elucidate the effects of fuel composition, thermal stratification, and turbulence on PRF homogeneous charge compression-ignition (HCCI) combustion. In general, it was found that the mean heat release rate increases slowly and the overall combustion occurs fast with increasing thermal stratification regardless of the fuel composition. In addition, the effect of the fuel composition on the ignition characteristics of PRF/air mixtures was found to be significantly reduced with increasing thermal stratification. The reduction of the fuel effect under the high degree of thermal stratification is caused by the nearly identical propagation characteristics of deflagrations of different PRF/air mixtures. Ignition Damkohler number is proposed to quantify the successful development of deflagrations from nascent ignition kernels. It was verified that for cases with large ignition Damkohler number, turbulence with high intensity and short-timescale can advance the overall combustion by increasing turbulent flame area instead of homogenizing initial mixture inhomogeneities.
안성찬(Sung Chan An),김승욱(Seung Ook Kim),김준철(Joon Cheol Kim),박승현(Seung Hyun Park),박종후(Jong Hwoo Park),박현중(Hyun Joong Park),조영우(Young Woo Jo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In this paper, we will explain the need for a virtual model so-called Digital Twin technology in the ship engine field, and the applications of the virtual models. Unlike small automobile engines, ship engines need a lot of time and cost to do experiments. The development of the virtual models in the field of ship engines is essential to get competitiveness in the ship engine business. Hyundai Heavy Industries (HHI) virtual model technology, which will be introduced in this paper, can be divided into three main areas. Virtual models are used for the following areas: engine design, engine testing, and maintenance. In engine design, a predictive model is constructed based on combustion analysis, structural analysis, and performance analysis to predict engine performance required for designing the target value. For engine testing, the total number of tests can be reduced by using virtual models to determine the direction of the test or in conjunction with existing test data to reduce time and cost. In terms of maintenance, the ship engine’s big data system is used based on numerous engine operating data accumulated so far and is used to predict failures and diagnose engines by utilizing virtual models with AI technology. Lastly, this paper will be concluded by discussing the future of virtual model technology in the ship engine field by introducing “Smart Engine 5.0” which is the future of the virtual model pursued by HHI.
Azide투여가 고농도산소 노출에 의한 마우스 간내 반응성 산소의 발생과 제거에 미치는 영향
이인길,박건택,김승욱,백광진,권년수,이희성 중앙대학교 의과대학 의과학연구소 1993 中央醫大誌 Vol.18 No.2
An increased production of reactive oxygen species has been postulated as a major pathogenic factor of the tissue demage occurring in high oxygen environment. Azide could enhance the oxygen toxicity by inhibiting superoxide dismutase and catalase, enzymes which remove reactive oxygen species. Mice were treated intraperitoneally with azideI8.1㎎/㎏ body weight), and placed in a chamber saturated with 100 % O_2 for 3, 6, 12, 24, 48 or 72 h. Superoxide radical generation, and activities of xanthine oxidase, superoxide dismutase and catalase in homogenate of the mouse liver were measured. At 3 h of the treatment with azide/100 % O_2, superoxide radical generation was enhanced to more than 12 times of the control. Such increment was much higher in the liver of mice treated with both azide and 100 % O_2 than in that with either azide or 100 % O_2 alone. On the other hand, the activities of mitochondrial Mn-superoxide dismutase and catalase were decreased, while Cu, Zn-superoxide dismutase activity was elevated by the azide/oxygen treatment. Xanthine oxidase activity was markedly increased by the azide/oxygen treatment. These results indicate that superoxide radical generation in the mouse liver by the azide/oxygen treatment may be due to the inhibiton of Mn-superoxide dismutase and catalase, and due to increased xanthine oxidase activity. Treatment with azide alone did not decrease the activities of Mn-superoxide dismutase and catalase. This result suggested that azide did not effectively inhibit these enzymes in vivo.