• Bulletin of the Korean Mathematical Society
• /
• v.55 no.2
• /
• pp.591-598
• /
• 2018

This paper is concerned with global existence of weak solutions to the relativistic Vlasov-Klein-Gordon system. The energy of this system is conserved, but the interaction term ${\int}_{{\mathbb{R}}^n}\;{\rho}{\varphi}dx$ in it need not be positive. So far existence of global weak solutions has been established only for small initial data [9, 14]. In two dimensions, this paper shows that the interaction term can be estimated by the kinetic energy to the power of ${\frac{4q-4}{3q-2}}$ for 1 < q < 2. As a consequence, global existence of weak solutions for general initial data is obtained.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.5B no.1
• /
• pp.90-94
• /
• 2005

As the structure of the piezoelectric bimorph cantilever becomes increasingly more complicated, a more accurate and efficient analysis of piezoelectric media is needed. In this paper, the piezoelectric transducer is analyzed by using the three-dimensional finite element method. The validity of the three-dimensional finite element routine is confirmed by comparing the experimental result. The resonance characteristics, such as resonance frequency and anti-resonance frequency, of the piezoelectric cantilever are calculated by the experimentally verified three dimensional finite element method. Subsequently, the characteristics, such as mechanical displacement and impedance, are calculated at the resonance frequency. Besides, to design the piezoelectric bimorph cantilever shape that maximizes displacement at the tip, the ES (Evolution Strategy) algorithm is applied. Finally, optimal design for the fan of the piezoelectric cantilever is fulfilled to obtain maximum displacement at the tip. From these results, the application potentiality of the piezoelectric bimorph cantilever fan is identified.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07b
• /
• pp.984-987
• /
• 2002

In this study, It is to synthesize PPV-copolymer and to make polymer electroluminesence device in single layer of ITO/PPV -copolymer/metal. and then it has been realized basic characteristics for display device through analysis and recognized application possibility by luminous material. PPV-copolymer is used spin coating method and electrode is evaporated of vacuum deposition method by changing materials. The result of experiment, The PPV-copolymer used this study emitted blue color, could be discovered a change of emttion characteristic by electrode material.

• Journal of the East Asian Society of Dietary Life
• /
• v.22 no.3
• /
• pp.386-391
• /
• 2012

The principal objective of this study was to evaluate the quality characteristics of black garlic milk tofu prepared with five different levels (0%, 0.5%, 1%, 1.5%, and 2.0%) of black garlic concentrate (BG0~BG4). We conducted the pH, total phenol and flavonoids, Hunter's color values, mechanical characteristics, and a sensory evaluation analysis of black garlic milk tofu. The total phenol and flavonoid content of black garlic concentrate were 1.67mg/100 g and 1.07 mg/100 g. The more black garlic concentrate increased, the more lightness (L) decreased, but redness(a) and yellowness (b) increased. The hardness, gumminess, and chewiness scores significantly increased (p<0.05) in all black garlic milk tofu samples. In color, taste, flavor, texture, and overall quality, the score of milk tofu with 1.0% black garlic concentrate (BG2) increased the most.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.587-590
• /
• 2003

In flat-plate floors, slab-column connections are broken down with a brittle shear failure. And it can cause the collapse of the whole structures. Thus, the proper method of shear reinforcement in flat plate-column connections must be required. The objective of this study is to compare shear reinforcement specimens using lattice bars to no shear reinforcement specimens in view of shear strength and ductility of the flat plate-column connections. The test results have shown that shear reinforcement specimens varying $\rho$, $b_0$/d and $C_1$/$C_2$ increase in shear strength by 36.85% and in ductility by 9.16 for no shear reinforcement specimens on the average. This results confirm the effectiveness of this type of shear reinforcement in improving shear strength and ductility.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.555-556
• /
• 2006

An experimental performance test has been carried out to improve a new blade with higher performance. Most of blades of the fan are designed to be a seamless and simple type, and the flow momentum can generally be evaluated to be comparatively low. Because some portions of the blowing winds can easily be passed through the seamless sharp edge of the blade, and several results studied on these problems have been reported: on the simple blade with edge-line seam, on the simple blade with guide seam. However the results do not show the remarkable increasement of performance of the blades. In this experimental performance test of the blades the design techniques of the blades with double seams (stem seam and edge seam) and comparison tests have been focused. As a first step the comparisons of velocity distributions and flow-rates depending upon the blade are presented in this paper.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.233-236
• /
• 2002

The high-pressurized spray nozzle is used f3r special washing and cutting with strong impact force. The performance of this nozzle, which focused on spray penetration and radial dispersion, was mainly investigated to maximize the momentum and minimize the flow loss. Hence, our experimental research was conducted by changing the aspect ratio ranging from 0 to 3 with nozzle outlet of 1.1. The spray trajectory far high-pressurized water was experimentally investigated using PDPA diagnostics, which was available at spray downstream region. As the spray at upstream near the nozzle exit did not show the improved disintegration. The results showed empirical correlation with regard to non-dimensional axial velocity distribution, spray penetration, and radial spreading rate with photographic visualization.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.667-670
• /
• 2002

Vehicle's airtight integrity is a very important factor that greatly affects passenger's habitability. However, when a door is closed, the pressure in the passenger compartment increases due to the vehicle's airtight integrity. That pressurizes the eardrums of the passenger, and makes passenger unpleasant. Thus, in this study, the configurations of air ventilation hasve been investigated to reduce pressure in the passenger compartment. Truck cab is utilized to measure the pressure in the passenger compartment. Various kinds of air ventilations are considered to find out optimized pressure in truck cab when a door is closed.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.693-698
• /
• 2001

An experimental study was carried out with an aerated nozzle. This nozzle was well known that the performance of the atomization is better than other ones even though the supplied air pressure is lower than that of them. The purpose of this investigation is to provide the essential information of the aerated nozzle from the nozzle exit. The experimental work was performed in order to analyze the characteristics of the overall flow field from the nozzle exit. The 2-D PDPA system was used to acquire the data in the concerned region. The characteristics of the mean velocity distribution, half-width, and SMD were mainly analyzed. Also the correlation between turbulent kinetic energy and SMD was described with ALR.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.9 no.2
• /
• pp.50-60
• /
• 1989

The control of resistance of foil strain gauge is accomplished by means of etching technique. Thus, there is an irregularity in metal foil. In order to solve this problem, ion sputter machining method has been used to make strain gauge in this study and the characteristics of this strain gauge are investigated. As the result of this study, it was possible to make a flexible strain gauge which can be used to measure the stress. The strain gauge made by authors shows superior characteristics in creep, O point variance, hysteresis and nonlinearity by surrounding temperature.