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Development of interpolation-free PTV
전민규,도덕희,조경래 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.9
A new particle tracking velocimetry (PTV) algorithm, which has no interpolation process requirement, has been constructed. An affine transformation and a hybrid fitness function were used to obtain final vector fields. A match probability method (MPM)-based PTV algorithm was used to save calculation convergences. The constructed algorithm was tested with synthetic images using the numerical data of Taylor-Green vortex flow and experimental images for the flow of a rectangular body with Re = 5300. Results obtained by the constructed PTV algorithm were compared with those obtained by the conventional cross-correlation particle image velocimetry (PIV) and the MPM. Comparison results revealed that the constructed interpolation-free PTV (IFPTV) algorithm demonstrated better performance than the aforementioned PIV and PTV algorithms. Furthermore, the constructed PTV algorithm does not need an error removal and interpolation process, enabling easy processing in PTV calculations while providing high-resolution grid vectors.
Effects of propane pyrolysis on basic flame structures of non-premixed jet flame
전민규,조문수,이민정,김남일,류홍선 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9
Recently, high temperature combustion techniques have been extensively adopted to improve thermal efficiency of combustion devices. When the temperature is sufficiently high, fuel pyrolysis may occur and then the flame structure can be affected. Thus, the understandingflame structure at high temperature coupled with fuel pyrolysis is essential to design burners operated in high temperature environments. In this study, propane was heated up to 1100 K using an electric heater, and the characteristics of fuel pyrolysis and its effectson non-premixed jet flames were experimentally investigated at room temperature. Normalized volume flow rates and components weremeasured regarding the fuel pyrolysis. The normalized volume flow rates of the propane were increased significantly through the pyrolysisprocess, and they agreed with numerical results based on an ordinary chemical mechanism. Variations of flame height and soot regionwere compared for the pyrolysis temperature. Conclusively, in spite of the significant growth in the volume flow rate by the propanepyrolysis, flame height was not significantly affected. On the contrary, the soot region was slightly extended by the fuel pyrolysis. Thisstudy will help to extend understanding on jet flame characteristics especially at high temperature conditions.
Optical temperature measurement method of premixed flames using a multi-laser system
전민규,도덕희,Yoshihiro Deguchi 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
The temperature distribution of a methane-air premixed flame was measured by the optical measurement technique. The absorption line was decomposed through 3rd order polynomial analysis, and the simultaneous multiplicative algebraic reconstruction technique (SMART) algorithm was adopted for computed tomography-tunable diode laser absorption spectroscopy (CT-TDLAS) data reconstruction. Methane-air premixed combustion system was used to construct laminar and turbulent flames. A double tube structure was adopted to solve combustion instability factors that occur when turbulent flames are generated. To overcome the high-temperature measurement limitations of a single laser system, two types of distributed feedback (DFB) lasers were mixed and measured. The relative error in temperature was largely confirmed at the central location of the burner. It was about 1.22 % for the laminar flame and 14.47 % for the turbulent flame.
Development of measurement technique of explosive flame using an optical measurement method
전민규,Jeong-Woong Hong,Kyoungmin Kim,도덕희 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.12
It is essential in weapons systems to understand how much explosive power is applied according to various chemicals and methods of the explosion. In particular, to measure dynamic thermal phenomena and analyze thermal properties under high-temperature and highpressure conditions. Although many researchers have used thermocouples to measure the temperature during an explosion, this method has an error in the temperature measurement as the radiant heat flux increases. Another measurement method is needed to solve this problem. During an explosion in a shock tube, the temperature change was measured with a thermocouple and a pressure sensor. To solve the limitations of the thermocouple's measurement responsiveness in temperature measurement was compared with the TDLD (tunable diode laser detection) method. In the case of the TDLD method, the time to reach the peak was measured an average 0.0207 sec faster than the thermocouple. Moreover, the peak average temperature was 15.8 °C higher than that of the thermocouple.
Blockchain-Based User-Participatory Game Update:Maze Escape Game Case
전민규,황지연,나현숙 한국게임학회 2019 한국게임학회 논문지 Vol.19 No.4
In this note, we propose a game system to fairly and transparently control and update game variables using blockchain. As an example, we present an Ethereum-based maze escape game, being the first blockchain-based maze game and the first attempt to control game level through blockchain. In this system, the level function computes maze level reflecting the amount of maze walls purchased/sold by users. Using blockchain for game management saves human and economic resources and prevents unfair practice of game developers unilaterally manipulating game level or item enhancement rate.
전민규,김원배,한국찬,나석주 대한용접접합학회 1995 대한용접·접합학회지 Vol.13 No.3
An advantage offered by brazing over fusion welding is that strong joints may be produced at relatively low heat input. To minimize the thermal effects and maintain the desired dimension of assemblies. the CO$_{2}$ laser beam can be applied to the brazed joint of pin and plate as a micro heat source. This paper presents a analysis model of the laser brazing process considering the laser beam mode and heat flow in brazed parts by using the finite element method. The simulation results were compared with the experimental results obtained from the infrared temperature sensing system. Based on these results, the proper process parameters were investigated to get a good joining quality. The influence of the beam mode change was examined with respect to the temperature distribution and joint quality.