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홍대희,김우동,김태형,민원,Hong, Daehie,Kim, Woo-Dong,Kim, Tae-Hyung,Min, Won 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.1
The tunnels built in recent years are equipped with traffic counters and pollution sensors (mostly, CO and Vl sensors). Utilizing these built-in sensors, it is possible to develop an algorithm to estimate the amount of pollutants exhausted from the each class of cars passing through the tunnel. These estimated data can be effectively utilized not only for ventilation control but also for designing ventilation facilities. The diffusion of pollutants in a tunnel can be described with one-dimensional diffusion-convection equation. This equation is approximated with interpolation functions and weighted residual method converting to adequate form for standard state estimate algorithms. With this converted equations, a least square optimization based algorithm is developed, whose outputs are the estimated amounts of pollutants emitted from each class of cars. In order to verify the feasibility of the developed algorithms, simulations are performed with the real data acquisitioned from the Tunnae tunnel located in Young-Dong highway in Korea.
A Study on the Tolerance of Composite Seam Clamp for Paper Container Forming Process
홍준호(Junho Hong),위형종(Hyoungjong Wi),정상열(Sang Yeol Jeong),김학민(Hakmin Kim),홍대희(Daehie Hong) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.7
Precise installation of a seam clamp is crucial as failure to do so will lead to defects, compromising the quality of paper containers. Even experts spend 90-120 minutes, which comprises 4.7 percent -6.25 percent of the replacement and adjustment process on a paper container manufacturing machine. To overcome an undesirable replacement procedure, a composite seam clamp was devised. The objective of this paper is to enhance the quality of a seam of a paper container and reduce time replacing seam clamps. The composite seam clamp was designed based on the Guerin process. Silicon rubber, which can be used in the temperature range of the paper container manufacturing process (110-130℃), was selected. To validate performance of the steel and composite seam clamp, 13 error situations resulted from translation and rotating misalignment of seam clamps were set and simulated. Through FEM (Finite Element Method) simulation, this paper confirms that the composite seam clamp shows higher transmission of clamping pressure compared to steel seam clamps in error situations. The feasibility of the composite seam clamp was validated in reducing replacement time of seam clamps through on-site tests.
3D Cutting Machine of EPS Foam for Manufacturing Free-Formed Concrete Mold
서정환(Junghwan Seo),홍대희(Daehie Hong) Korean Society for Precision Engineering 2017 한국정밀공학회지 Vol.34 No.1
We used a construction method using a CNC milling machine, where free-formed molds were made by cutting EPS (Expanded PolyStyrene) foam with the CNC machine, to build free-formed buildings. CNC milling is off-the-shelf technology that can easily cut EPS foam; however its production cost is too high and the time to manufacture an EPS mold is too long. This paper proposes a novel cutting machine with a fast and cost effective mechanism to manufacture EPS concrete molds. Our machine comprises a cutter and Cartesian coordinate type moving mechanism, where the cutter cuts EPS foam using a hotwire in the shape of ‘Π’ and is capable of adjusting its cutting angle in real-time while keeping its cutting width. We proved through cutting experiments on the CNC machine that cutting time was greatly shortened compared to the conventional method and that the resulting concrete mold satisfied manufacturing precision.