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871.
Moonkeun KimAlexander Efremov Hyun Woo LeeHyung-Ho Park MunPyo HongNam Ki Min Kwang-Ho Kwon 《Thin solid films》2011,519(20):6708-6711
Etching characteristics and the mechanism of HfO2 thin films in Cl2/Ar inductively-coupled plasma were investigated. The etch rate of HfO2 was measured as a function of the Cl2/Ar mixing ratio in the range of 0 to 100% Ar at a fixed gas pressure (6 mTorr), input power (700 W), and bias power (300 W). We found that an increase in the Ar mixing ratio resulted in a monotonic decrease in the HfO2 etch rate in the range of 10.3 to 0.7 nm/min while the etch rate of the photoresist increased from 152.1 to 375.0 nm/min for 0 to 100% Ar. To examine the etching mechanism of HfO2 films, we combined plasma diagnostics using Langmuir probes and quadrupole mass spectrometry with global (zero-dimensional) plasma modeling. We found that the HfO2 etching process was not controlled by ion-surface interaction kinetics and formally corresponds to the reaction rate-limited etch regime. 相似文献
872.
Occurrence and removal efficiencies of 20 pharmaceuticals and personal care products (PPCPs) including antibiotics, hormones, and several other miscellaneous pharmaceuticals (analgesics, antiepileptics, antilipidemics, antihypertensives, antiseptics, and stimulants) were investigated in five wastewater treatment plants (WWTPs) of Ulsan, the largest industrial city of Korea. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by High-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The results showed that acetaminophen, atenolol and lincomycin were the main individual pollutants usually found in concentrations over 10 μg/L in the sewage influent. In the WWTPs, the concentrations of analgesic acetaminophen, stimulant caffeine, hormones estriol and estradiol decreased by over 99%. On the contrary, the antibiotic sulfamethazine, the antihypertensive metoprolol, and the antiepileptic carbamazepine exhibited removal efficiencies below 30%. Particularly, removal of antibiotics was observed to vary between − 11.2 and 69%. In the primary treatment (physico-chemical processes), the removal of pharmaceuticals was insignificant (up to 28%) and removal of majority of the pharmaceuticals occurred during the secondary treatment (biological processes). The compounds lincomycin, carbamazepine, atenolol, metoprolol, and triclosan showed better removal in WWTPs employing modified activated sludge process with co-existence of anoxic-oxic condition. Further investigation into the design and operational aspects of the biological processes is warranted for the efficient removal of PPCPs, particularly antibiotics, to secure healthy water resource in the receiving downstream, thereby ensuring a sustainable water cycle management. 相似文献
873.
Shape design of a tire contour based on approximation model 总被引:1,自引:0,他引:1
Dong Woo Lee Jong Kyu Kim Sung Rae Kim Kwon-Hee Lee 《Journal of Mechanical Science and Technology》2011,25(1):149-155
The basic purpose of a tire is to enhance vehicle performances such as driving performance, rolling resistance, durability,
ride comfort, noise, wear resistance, etc. by acting as a flexible cushion. To meet the demand for increased vehicle performances,
the design method of a tire has advanced. This study proposes a structural design method for tire contour by considering both
the tread contour and the sidewall contour, simultaneously. Existing studies of tire contour optimization have focused on
the tread contour and the sidewall, separately. Durability, maneuverability and ride comfort are performances that are commonly
investigated in tire contour design. Durability, maneuverability and ride comfort can be measured by the values of the strain
energy density, tension and vertical stiffness, respectively. The optimization technique using a metamodel is introduced to
maximize durability while satisfying the imposed constraints of tension and ride comfort. To achieve this, the responses defined
in the optimization formulation are expressed mathematically in explicit form with respect to the design variables by using
the kriging surrogate model, resulting in a simple optimization problem. Then, the simulated annealing algorithm is utilized
to find the global optimum. 相似文献
874.
Bevel gear processing has diversified based on constant technical developments in forging, CNC cutting and hob design. Standardization
of bevel gears is in higher demand than ever for different bevel gear systems that have different shapes and forms according
to processing methods. With advantages such as excellent compatibility and the ability to absorb assembly errors well, the
involute gear is referred to as the spherical involute tooth profile in bevel gear systems. This paper explains the geometrical
characteristics and kinematic behavior of spherical involute gears. A spherical involute function is derived to effectively
represent tooth profiles, and a common basic rack is developed using the equation of meshing to generate spherical involute
gears. This study also analyzes the general characteristics of spherical involute gears and discusses the issue of bevel-gear
standardization. 相似文献
875.
Jong Won Choi Il Hwan Lee Min Soo Kim 《Journal of Mechanical Science and Technology》2011,25(6):1415-1422
This paper describes the steady state heating performance of a multi-type heat pump system. The operation range of such systems
has extended to cover various situations, and there is a requirement for systems that provide sufficient performance in those
situations. Thus, many researchers have made efforts to design a controller or develop control logic that ensures optimal
operation. In a multi-type heat pump, effective control of individual indoor units is necessary for satisfying heating or
cooling demands. In such systems, a successfully designed controller must consider cross-coupling effects among indoor units
during alteration of control variables such as expansion valve opening and compressor speed. Thus, we investigated cross-coupling
effects among indoor units under various working conditions to help determine an optimum and effective control variable. The
heating performance and the relationship among the operating variables of the multi-type heat pump system with R410A indicated
that the temperature of the indoor units’ secondary fluid was a suitable control variable. 相似文献
876.
Kang Woo Chun Hun-Jik Chung Suk Ho Chung Jae Hyuk Choi 《Journal of Mechanical Science and Technology》2011,25(11):2943-2949
The flame structure, extinction, and NOx emission characteristics of syngas/air nonpremixed flames, have been investigated numerically. The extinction stretch rate
increased with the increase in the hydrogen proportion in the syngas and with lower fuel dilution and higher initial temperature.
It also increased with pressure, except for the case of highly diluted fuel at high pressure. The maximum temperature and
the emission index of nitric oxides (EINOx) also increased in aforementioned conditions. The EINOx decreased with stretch rate in general, while the decreasing rate was found to be somewhat different between the cases of
N2 and CO2 dilutions. The reaction paths of NOx formation were analyzed and represented as NO reaction path diagram. The increase in N radical resulted in larger NOx production at high initial temperature and pressure. As the pressure increases, EINOx increases slower due to the third-body recombination. The thermal NO mechanism is weakened for high dilution cases and non-thermal
mechanisms prevail. The combustion conditions achieving higher extinction stretch rate can be lead to more NOx emission, therefore that the selection of optimum operation range is needed in syngas combustion. 相似文献
877.
Evaluation of the control performance of hydronic radiant heating systems based on the emulation using hardware-in-the-loop simulation 总被引:1,自引:0,他引:1
This study presents an emulation method to evaluate the control performance of a hydronic radiant heating system. Since heat output in the system is dependent on the pressure loss and flow rate in the hydronic network, the interaction between thermal and hydronic models needs to be considered in the evaluation of the control performance. For this reason, many studies apply an integrated simulation to the evaluation; however, the analysis of the hydronic network sometimes leads to unreliable results due to the improper initial values for algebraic loops or the lack of modeling information on the hydronic components. In order to deal with this problem, this study suggests an emulation method, where the hydronic network is replaced by real hardware and the building physics is analyzed by a simulation. In the emulation, the pressure loss and flow rate in the hydronic network were represented by replacing the real pipe with equivalent hydraulic resistance. In addition, by using real control systems that connect the hydronic network and building simulation, the interaction between building physics and hydronic network could be considered in the evaluation. Based on the proposed emulation method, the performance of several control strategies was evaluated in terms of the accuracy and the rise time. The result shows that the individual control needs to be combined with hydronic balancing for more accurate control. Hydronic control devices such as a flow limit valve and a pressure differential control valve also proved to be helpful to the improvement of the control performance. 相似文献
878.
首尔圣玛丽医院力争与世界上技术最先进的医院匹敌,成为最大的天主教医疗建筑,并为天主教会树立医疗设施的典范。新建的首尔圣玛丽医院共28层,天主教医学中心邀请了许多重要人士参加其盛大的开业典礼 相似文献
879.
In Taek Choi Ban Seok You Yu Kyung Eom Myung Jong Ju Won Seok Choi Sung Ho Kang Min Soo Kang Kang Deuk Seo Ji Yeoun Hong Sang Hyun Song Ji-Woon Yang Hwan Kyu Kim 《Organic Electronics》2014,15(11):3316-3326
Triarylamine-based dual-function coadsorbents containing a carboxylic acid acceptor linked by extended π-conjugation aryl linkers (e.g., phenylene: HC-A3, naphthalene: HC-A4 and anthracene: HC-A5) were newly designed and synthesized. They were used as coadsorbents in organic dye-sensitized solar cells (DSSCs) based on a porphyrin dye (hexyloxy-biphenyl-ZnP-CN-COOH (HOP)). For comparison, the π-conjugated phenyl linker (HC-A3) previously developed by our group was also used as a coadsorbent. The structural effects on the photophysical and electrochemical properties and DSSC performance were systematically investigated. As a result, the DSSCs based on HC-A4 and HC-5 displayed power conversion efficiencies (PCEs) of 8.2% and 5.1%, respectively, while the HC-A3-based DSSC achieved a PCE of 7.7%. In the case of HC-A4, both the short-circuit photocurrent densities (Jsc) and open-circuit voltages (Voc) of DSSCs were simultaneously improved to a large extent due to the more effective prevention of π−π stacking of organic dye molecules and the better light-harvesting effect at short wavelengths. The HC-A5-based DSSC exhibited a much lower short-circuit current (Jsc) and open-circuit voltages (Voc) compared to the HC-A4-based DSSC, due to the fact that the dihedral angle of the π-conjugated linkers was too high for electron injection into the TiO2 conduction band (CB) level. This had a reduced effect on preventing the π−π stacking of dye molecules, resulting in lower Jsc and Voc values. 相似文献
880.
Highly Fluorescent and Color‐Tunable Exciplex Emission from Poly(N‐vinylcarbazole) Film Containing Nanostructured Supramolecular Acceptors
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Jong H. Kim Byeong‐Kwan An Seong‐Jun Yoon Sang Kyu Park Ji Eon Kwon Chang‐Keun Lim Soo Young Park 《Advanced functional materials》2014,24(19):2746-2753
Highly fluorescent excited‐state charge‐transfer complexes (exciplexes) formed at the interfacial region between a polymeric donor matrix, here, poly(N‐vinylcarbazole), and embedded nanostructured acceptors are characterized for their photophysical properties. Exciplex‐to‐exciton emission switching is observed after solvent vapor annealing (SVA) due to the size evolution of the nanostructures beyond the exciton diffusion length. Color‐tunable exiplex emission (sky blue, green, and orange) is demonstrated for three different nanostructured acceptors with the same HOMO–LUMO gap (i.e., the same blue excitonic emission) but with different electron affinity. White‐emitting poly(N‐vinylcarbazole) film is also fabricated, simply by incorporating mixed supramolecular acceptors, which provide independent exciplex emissions. This study presents important insights into the excited‐state intermolecular interaction at the well‐defined nanoscale interface and suggests an efficient way to obtain multicolored exciplex emissions. 相似文献