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화학 용액 증착 공정으로 제조된 후막 Pb(Zr_(0.52), Ti_(0.48))O₃의 e_(31,f) 특성
박준식,양성준,강성군,나경환 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9
Thick Pb(Zr_(0.52), Ti_(0.48))O₃(briefly, PZT) films are required for the cases of micro actuators and sensors with high driving force, high breakdown voltage and high sensitivity, and so on. In this work, thick PZT films were fabricated by chemical solution deposition process. Total 16 types of samples using thick PZT films with thicknesses, about 1 ㎛ and 2 ㎛, and Pt top electrodes shapes for measuring effective transverse piezoelectric coefficients (e_(31,f)) were prepared using MEMS processes. All samples were characterized by fabricated e_(31,f) measurement system before and after poling process at 125 kV/cm and 150℃ for 10 min. |e_(31,f)| values of samples after poling were higher than samples before poling. Those of 2 ㎛ thick PZT films were also higher than 1 ㎛ thick PZT films. We found that |e_(31,f)| was directly related with {111} to {h00} crystal structures of thick PZT films. And those with narrow electrodes (x₁- x_(0)) as top Pt electrodes were also higher than cases with wide top Pt electrodes in agreement with given equation.
사과 品種別 Vitamine C의 含量에 關한 調査 硏究
朴相眩,姜君中 진주산업대학교 1980 論文集 Vol.18 No.-
各 品種別 사과의 Vitamin C의 含量, pH의 수준 및 당도의 차이를 알아 보기 위해서 본 시험을 실시하였으며 그 結果를 요약하면 다음과 같다. 各 品種別 Vitamin C 含量의 범위는 4.9㎎/100g의 수준이었다. 인도(pH5)와 홍옥(pH3.6)을 제외한 대부분의 品種의 酸度는 pH4 정도로서 거의 비슷하였다. 各 品種別 糖度의 範圍는 9.9에서 14.1이었다. 紅玉은 全體의 品種 中에서 酸度와 糖度는 가장 낮았으나 Vitamin C의 含量은 가장 높은 品種인 것으로 나타났다. This experiment was carried out to investigate the amount of ascorbic acid, pH levels and sugar contents in different varieties of apple produced in Keoung Sang Buk province, and the results were as follows; The ascorbic acid contents of different varieties of apple ranged from 4.9㎎/100g to 9.8㎎/100g. The pH values were similar in all varieties examined except Indo (pH5) and Hongok (pH 3.4). The sugar contents of the different varieties of apple ranged from 9.9 to 14.1. The variety of Hongok had the highest ascorbic acid contents and the lowest sugar contents in all varieties.
이종성,최군호,조용석,박기헌 成均館大學校 科學技術硏究所 1996 論文集 Vol.47 No.1
This paper treats the guide path tracking problem of an experimental automated guided vehicle. An experimental guide path is made of aluminium foil which has width of 2[cm]. When a aluminium foil is used as the guide path, this may be less stable than a conservative rail guide path. In this case, it is necessary to control the steering system which influences the system stability. A digital PD(Proportional and Derivative)controller is used to manipulate the steering system and it is verified by laboratory experiments that the designed AGV tracks the guide path within the range of 3.2[cm] deviation. In order to increase accuracy of the guide path tracking, it would be necessary to introduce the constant speed mode and slow-down speed mode according to the state of guide path.
김도군,천상욱,김병군,서인석,박철휘,김성준,류수현 대한상하수도학회 2002 상하수도학회지 Vol.16 No.4
Intermittent aeration processes have been much of interest as an excellent alternative for nutrients removal for upgrading secondary wastewater treatment plants, with minimum modification. Also, operational flexibility of those proposes a good opportunity for newly planed plants. Here, a pilot study was conducted to evaluate the performance of a continuous flow intermittent aeration process (KSDeN^TM process). The influent was collected at the effluent channel of the grit chamber of a large sewage treatment plant. The influent characteristics with standard deviation were 243.2±170.9mg/L for TCOD_cr, 47.5 13.9mg/L for T-N, 8.4±8.3mg/L for T-P and 5.2±1.8 for C/N ratio. Effluent of 1^st sedimentation tank was 208.2±87.6mg/L for TCOD_cr, 35.0±10.3mg/L for T-N, 4.8±1.9mg/L for T-P and 6.1±2.3 for C/N ratio. The average removal efficiencies of TCOD_cr, T-N and T-P were 93.6, 77.0 and 86.4% and effluent TCOD_cr, T-N and T-P concentrations were 12.5, 9.2 and 0.7mg/L respectively, satisfying regulatory limits. Alkalinity deficiency was not observed during the oxic periods, which is one of the special features of an intermittent aeration process. The results showed higher COD, T-N and T-P removal efficiencies and stability with varying influent conditions, compared to other conventional fixed phase nutrients removal processes.
Fabrication of Piezoelectric Micro Bending Actuators Using Sol-Gel Thick PZT films
Park, Joon-Shik,Yang, Seong-Jun,Park, Kwang-Bum,Yoon, Dae-Won,Park, Hyo-Derk,Kang, Sung-Goon,Lee, Nak-Kyu,Na, Kyoung-Hoan The Korean Society Of Semiconductor Display Techno 2004 반도체디스플레이기술학회지 Vol.3 No.3
Fabrication and electrical and mechanical properties of piezoelectric micro bending actuators (PMBA) using sol-gel-multi-coated thick PZT films and MEMS processes were investigated. PMBA could be used for design and fabrication of micro fluidic devices, for example, micro-pumps, micro dispensers, and so on. PMBA were fabricated using 2 um thick PZT films on Pt (350 nm)/$SiO_2$ (500 nm)/Si ($300\mu\textrm{m}$) substrates and MEMS processes. 7 types of PMBA were fabricated with areas of silicon diaphragms, PZT films and top electrodes. When the sizes of silicon diaphragms, PZT films and Pt top electrodes were reduced from 3000$\times$$1389\mu\textrm{m}$, 4000$\times$$1000\mu\textrm{m}$ and 4000$\times$$900\mu\textrm{m}$ down to 14%, 14% and 11 % of them, respectively, the center displacements of PMBA were decreased from 0.68 um to 0.10 um at 5 Hz and 12 Vpp. So, PMBA with large areas showed larger displacements than PMBA with small areas and experimental results were also good agreement with the plate and shell theory.
Simulation of fluid-flexible body interaction with heat transfer
Park, Sung Goon,Chang, Cheong Bong,Kim, Boyoung,Sung, Hyung Jin Elsevier 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.110 No.-
<P><B>Abstract</B></P> <P>An immersed boundary method (IBM) has been developed for the study of fluid-flexible body interactions with heat transfer. The fluid motion and temperature are defined on a fixed Eulerian grid, while the flexible body motion is defined on a moving Lagrangian grid. The governing equations for the fluid motion, the temperature, and the flexible body motion are solved independently on each grid system. To handle the momentum transfer between the flexible body and the surrounding fluid, the additional momentum forcing obtained by using the feedback forcing law is added to the fluid and body motion equations, enforcing the no-slip boundary condition of the fluid on the flexible body. The additional heat source between the heated body and the surrounding fluid can be calculated in a similar way to that used for obtaining the momentum force, which enforces the specified thermal boundary conditions on the body. The stability tests for the feedback forcing constants for the fluid-body interactions and the heat transfers are performed. Natural and forced convection problems with the isothermal and constant heat flux boundary conditions are simulated with a good agreement with those of previous studies. The simulations for the forced convective heat transfer around a flexible circular cylinder are performed. Two distinct stable states are observed depending on the Reynolds number and the flexible property of the cylinder, i.e., stretched-stable and self-sustained flapping states. The convective heat transfer is deteriorated for the stretched-stable state due to the elastic deformation, while enhanced up to 7% for the self-sustained flapping state compared to the heated rigid cylinder. The transverse pitching motion is related to the mean heat transfer during one flapping period. The longitudinal tapping motion determines when the heat transfer is maximized or minimized in the flapping cycle.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An immersed boundary method was proposed for fluid-body interaction with heat transfer. </LI> <LI> The same feedback forcing constants could be used for the momentum and heat transfers. </LI> <LI> Two states were observed for the flexible cylinder, i.e., stretched-stable and flapping states. </LI> <LI> The heat transfer was decreased for the stretched-stable state of the flexible cylinder. </LI> <LI> The heat transfer was increased for the self-sustained flapping state of the flexible cylinder. </LI> </UL> </P>