• International Journal of Automotive Technology
• /
• v.8 no.2
• /
• pp.137-147
• /
• 2007

Homogenous Charge Compression Ignition (HCCI) combustion systems can be broadly divided for the process applied to 4-stroke and 2-stroke engines. The former process is often referred to as simply HCCI combustion and the latter process as Active Thermo-Atmosphere Combustion (ATAC). The region of stable engine operation tends to differ greatly between the two processes. In this study, it was shown that the HCCI combustion process of a 4-stroke engine, characterized by the occurrence of autoignition under a high compression ratio, a lean mixture and wide open throttle operation, could be simulated by operating a 2-stroke engine at a higher compression ratio. On that basis, a comparison was made of the combustion characteristics of high-compression-ratio HCCI combustion and ATAC, characterized as autoignited combustion in the presence of a large quantity of residual gas at a low compression ratio and part throttle. The results showed that one major difference between these two combustion processes was their different degrees of susceptibility to the occurrence of cool flame reactions. Compared with high-compression-ratio HCCI combustion, the ignition timing of ATAC tended not to change in relation to different fuel octane numbers. Furthermore, when internal EGR was applied to high-compression-ratio HCCI combustion, it resulted in combustion characteristics resembling ATAC. Specifically, as the internal EGR rate was increased, the ignition timing showed less change in relation to changes in the octane number and the region of stable engine operation also approached that of ATAC.

• Journal of KIISE
• /
• v.43 no.1
• /
• pp.34-39
• /
• 2016

JavaScript is widely used in web pages with HTML. Many JavaScript engines adopt Just-in-time compilers to accelerate the execution of JavaScript programs. Recently, many newly introduced devices are adopting 64-bit CPUs instead of 32-bit and Just-in-time compilers for 64-bit CPU are slowly being introduced in JavaScript engines. However, there are many inefficiencies in the currently available Just-in-time compilers for 64-bit devices. Especially, the size of code is significantly increased compared to 32-bit devices, mainly due to 64-bit wide addresses in 64-bit devices. In this paper, we are going to address the inefficiencies introduced by 64-bit wide addresses and values in the Just-in-time compiler for the V8 JavaScript engine and propose more efficient ways of generating constant values and addresses to reduce the size of code. We implemented the proposed optimization in the V8 JavaScript engine and measured the size of code as well as performance improvements with Octane and SunSpider benchmarks. We observed a 3.6% performance gain and 0.7% code size reduction in Octane and a 0.32% performance gain and 2.8% code size reduction in SunSpider.

• Korean Chemical Engineering Research
• /
• v.43 no.4
• /
• pp.452-457
• /
• 2005

Foam-type MFI zeolite catalyst was prepared by dispersing fine ($-0.2{\mu}m$) particles of MFI zeolite on silicalite foam. Catalytic cracking of n-octane was investigated over the foam-type catalyst and Delplot method was employed to interpret product compositions for deducing reaction mechanism. The Si/Al molar ratio of dispersed MFI zeolite was estimated 25 and its dispersed amount of silicalite foam was 25 wt％. Since the apparent density of the foam type catalyst was very low $0.11g{\cdot}cm^{-3}$, the catalyst loading amount could be varied from 0.02 g to 0.5 g without concerning pressure drop, providing a wide variance in the residence time of the reactants and products. The conversion and olefin yield in the catalytic cracking of n-octane increased with the catalyst loading. The product composition was very simple and could be explained by applying the protolytic cracking mechanism when the catalyst loading was small. Higher loading of the catalyst brought about further reactions of cracked products, accumulating lower olefin and paraffin with low reactivity in product stream and resulting in complex product composition.

• Korean Chemical Engineering Research
• /
• v.45 no.6
• /
• pp.547-553
• /
• 2007

The catalytic cracking of n-octane over FER, MFI, MOR and BEA zeolites was studied by the protolytic cracking mechanism in order to understand the effect of pore structure of zeolites on their product composition and deactivation. The selectivities for $C_3$ and $C_3{^=}$ were high over the zeolites with medium pores due to additional cracking, while those for $C_4$ and $C_4{^=}$, the initial products, were high over the zeolites with large pores. MFI zeolite showed slow deactivation due to small carbon deposit, while FER zeolite with small pores deactivated rapidly with severe carbon deposit. The deactivation of BEA zeolite was slow even with a large amount of carbon deposit, but MOR zeolite showed a rapid deactivation even with a small amount of carbon deposit. The conversion measured along with the time on stream on these zeolite catalysts was simulated by a mechanism based on the simplified reaction path of n-octane cracking and the deactivation related to the pore blockage by carbon deposit.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.8
• /
• pp.1238-1240
• /
• 2004

• Proceedings of the Korean Society of Life Science Conference
• /
• 2001.09a
• /
• pp.61-61
• /
• 2001

• Korean Journal of Materials Research
• /
• v.4 no.8
• /
• pp.888-894
• /
• 1994

In detail of fracture and mechanical properties to carbon/BMI$(\pm 45^\circ)_{2s}$ discusses by acoustic emission and tensile testing. The bismaleimide resin from Boots Technochemie Co. was toughened by TM 120 from same Co. The weight proportions of TM 120 were fixed as 0, 5, 10, 15, 20, 25phr. The 0.2phr of 1, 4-diazobicyclo-(2, 2, 2)-octane(DABC0) was used as the accelerator. The used carbon fiber was T300 from Toray Co. The optimum additional proportion of TM120 was proved as 20phr by mechanical testing and at the same time by the results of acoustic emission. toughening agent gives significant influences on the fracture phenomena and mechanical strength.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.293-295
• /
• 2018

The final stage of the 3D work is rendering. After all, all 3D works are looking at via this rendered result, so the importance of the Rendering cannot be overstated. Because this is the final stage of 3D work, it requires a lot of theoretical and functional training in rendering control. However, However, it is difficult to invest as much time in college education in a limited period. This paper will compare and analyze the characteristics, and merits and demerits of these various kinds of Renderer (MARI, QUIXEL, Substace designer), and showed the result of analyses about the fact that educating which of the above 4 Renderers are helpful and beneficial for the students for the efficient education in the university where should teach much in the limited time.

• Journal of ILASS-Korea
• /
• v.5 no.4
• /
• pp.57-65
• /
• 2000

For this research an extension of the LIF technique that the LIEF(Laser Induced Exciplex Fluorescence) technique has been used LIEF technique is the unique method to allows the visualization of fuel vapor phase and liquid phase individually by capturing each signals of them. In this work performed that the basic procedure for advanced LIEF technique using TEA and benzene as dopants md high power KrF excimer laser to excite the dopants. Iso-octane is used as the fuel because it does not absorb light at the laser wavelength. The boiling point of benzene and TEA are $81^{\circ}C\;and89^{\circ}C$, respectively, in comparison to $99^{\circ}C$ for iso-octane. It is observed that the behavior and distribution of high pressed fuel injection from various test condition. The injection pressure is set as 3MPa. and 5MPa. And the ambient pressure of test chamber is atmospheric pressure and 1MPa, the ambient temperature of chamber is room temperature, $300^{\circ}C\;and\;500^{\circ}C$ to imitate the condition of GDI engine cylinder.

• Journal of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.218-223
• /
• 1982

The absorbance and fluorescence yields of chl-a vs. concentration of n-prOH in diethyl ether, benzene and iso-octane were shown the characteristic point which chl-a structures are changed to monomer by the solvation of oligomer, and the spectral differences of fluorescence excitation between oligomer and monomer were identified by fluorimetry. All the maximum wavelength of absorbance, fluorescence excitation and fluorescence emission were shifted to longer wavelength. The ratios of soret/red band were depended on the band intensions and the polarities of solution in organic solvents mixed with n-prOH.