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Structural Dynamics Modification of Slim Optical Disk Drive
Kyungtae Kim,Seungho Lim,No-Cheol Park,Young-Pil Park,Kyoung-Su Park,Ik-Joo Cha IEEE 2009 IEEE transactions on magnetics Vol.45 No.5
<P>This paper explores the dynamic characteristics of slim optical disk drives and the modification of their structural dynamics to reduce vibration using a simplified finite-element (FE) model. The FE model was constructed using simplified geometry and valid element types that effectively reflect the dynamic characteristics. The FE model was verified by experimental modal analysis (EMA). Design parameters were extracted and selected to modify the structural dynamics using design of experiments, topology optimization, and modal strain energy distribution. A prototype of the modified model was constructed and its anti-vibration performance was estimated using EMA and comparison of frequency response function.</P>
Park, Kyungtae,Won, Wangyun,Shin, Dongil Elsevier 2016 Journal of natural gas science and engineering Vol.34 No.-
<P><B>Abstract</B></P> <P>This paper presents the optimal design and operational solutions for a single mixed refrigerant liquefaction process under varying ambient temperatures. Given that the ambient temperature can affect the performance of air coolers and gas turbines, the correlation between changes in the ambient temperature and the performance of a single mixed refrigerant liquefaction process should be investigated. A simulation model and a mathematical model were devised and linked to find the optimal design and operational solutions for a single mixed refrigerant liquefaction process, and the particle swarm optimization method was adopted for used with the mathematical model. The results of this study can provide insight about taking advantage of low ambient temperatures for process engineers associated with LNG liquefaction plants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper presents the optimal design and operational solutions for a single mixed refrigerant (SMR) liquefaction process under varying ambient temperatures. </LI> <LI> This paper presents the effect of changes in the ambient temperature on the performance of the SMR process in terms of the capacity and the efficiency. </LI> <LI> This paper presents what factor plays an important role on the performance of the SMR process under varying temperatures. </LI> </UL> </P>
Kyungtae Park,Sang Yeob Lee,Boran Ji,Hamin Lee,Bo-Kook Jang,Ju-Sung Cho 한국원예학회 2021 한국원예학회 학술발표요지 Vol.2021 No.10
This study has stored Pulsatilla dahurica (Fisch. ex DC.) Spreng. seeds, which is known to be short in storage life, in various temperatures for one year to observe the changes in germinability and anticipated the appropriate storage temperature by performing accelerated aging experiment. Seeds for storage were collected in Andong-si, Gyeongsangbuk- do, late May 2020 and were sealed in plastic bag after the cleaning and stored in ‒20, 4, and 25°C chamber for one year. Control seeds used for Saturated Salt Accelerated Aging (SSAA) test was collected in early June 2021 at the same place. Each seed had measured of their sizes, weight of one thousand seeds, moisture content, E:S ratio, viability, and 4 weeks of initial percent germination, after the collection. SSAA test was performed using aging tray installed seed testing container with 40mL of saturated salt solution (NaCl). Seeds were aged for 72h at 41 and 47°C then their viability was measured with TZ test and were incubated in the chamber. After one year, germinability of stored seeds were measured with their percent germination (PG), start of germination (SG), mean germination time (MGT) and median germination time (T50) in 25/15°C (16/8h, White-LED, 30 μmol/m<SUP>-2</SUP>/s<SUP>-1</SUP> PPFD/Dark) chamber. As a result, seeds from both lots had E:S ratio of 0.23~0.24 indicating that they are morphologically immature. Initial viability of seed lots was over 98% and the PG had scored 97.5 (2020) and 98.0% (2021). PG of the seeds stored for one year in various temperatures were measured 100 (‒20°C), 98.5 (4°C) and 96.5% (25°C) which had no significant difference. However, SG was reduced to 11.2 (‒20°C), 11.5 (4°C) and 12.8 d (25°C) when compared to 15.0 before the storage. MGT and T50 were also reduced to 9.0 to 9.5 and 10.5 to 11.9 d respectively than the seeds before storage (18.0 and 17.5 d). Viability of SSAA tested stored seeds were 96 and 6 (‒20°C), 97 and 12 (4°C), 58 and 0% (25°C), 90 and 27% (non-stored) at 41 and 47°C respectively. On the other hand, SSAA tested seeds showed lower percent germination value than the measured viability. Percent germination of seeds with accelerated aging at 41°C were 44 (‒20°C), 66 (4°C) and 2% (25°C) which were lower than that of non-stored seeds (80%) and among them, the seeds stored at 4°C showed the highest value. Non-stored seeds with accelerated aging at 47°C showed percent germination of 28% where all the other stored seeds did not germinate. Therefore, the two experiments have confirmed that P. dahurica seeds do not deteriorate in their germinability even after one year of storage and SSAA test have proven that seeds stored at 4°C can preserve the viability relatively longer. Additionally, viability and the actual germinability of aged P. dahurica seeds are found to have some differences.