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Process analysis and test of manufacturing of sleeve spring-type torsional vibration damper
Hwang, Beom-Cheol,Bae, Won-Byong,Kim, Chul 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.6
In diesel engines, engine torque fluctuation inevitably produces torsional vibration. A sleeve spring-type damper commonly is used to reduce this vibration. In this paper, closed form equations to predict the spring constant of a sleeve spring and the torsional characteristics of a torsional vibration damper are proposed for calculation of the stiffness of the damper. The equations were verified through finite element analysis (FEA) and experiments. In addition, the stability of the sleeve spring-type torsional vibration damper was verified in an analysis of the inner star and outer star (the core components of the damper). A two-roll bending process, proposed in this paper, was determined to be the most suitable for manufacture of the sleeve springs. A closed form equation to calculate the forming radius, taking account of the springback effect, was derived, and a FEA method used to analyze the elasto-plastic problem was verified through an analysis of a $90^{\circ}$ bending process. The results of the analysis were in good agreement with the experiment. It is recommended that our proposed method, an advanced technique that can significantly reduce production costs, replace the conventional forming process.
A Study on the Performance of Pulse Jet Cleaning in High Temperature Filter
Byong-Ryol Kim,Seung-Chul Park,Byoung-Chul Park,Hyun-Jun Cho,Hyoung-Mo Oh,Tae-Won Hwang,Sang-Woon Shin 한국방사성폐기물학회 2005 방사성폐기물학회지 Vol.3 No.1
To evaluate parameters influencing on the dust removal of the High Temperature Filter(HTF) system, a computer simulation of fluid dynamics inside the system had been performed. The results showed that the optimum pulse jet periods were 50ms and 90ms for the 1000mm and 1500mm long filter elements respectively. Dust removal effect was very excellent under the pulse jet pressure of 3 bar. But the distance between the pulse jet nozzle and the venturi of a filter element had no meaningful effect on the performance with the variation from 5mm to 10mm. Compared to the dispersion mode of pulse jet, the collective mode of pulse jet flow was preferable in maintaining the pressure inside the system stable.
Carburization of Iron Using CO-H₂ Gas Mixture
Hwang, Ho-Sun,Chung, Uoo-Chang,Chung, Won-Sub,Cho, Young-Rae,Jung, Byong-Ho,Martin G.P. 대한금속재료학회 2004 METALS AND MATERIALS International Vol.10 No.1
Iron carbides formed on the surface of iron and iron oxide samples at 640℃ in a gas mixture of CO-H₂ were characterized by scanning electron microscopy (SEM), MGssbauer spectroscopy, X-ray diffraction patterns (XRD), and by measuring mass change. The Fe₃C amount of the samples has been quantitatively evaluated by the weight change during carburization. While Fe₂O₃ powder was mostly completed to Fe₃C in the early stage, within 5 min after reduction reactions, the conversion of Fe powder sample to Fe₃C (iron carbide) was almost finished after 10 min. The carburization rate of a Fe sheet was very slow and intermediate products (Fe₂C, Fe₃C₂) were observed. This phenomenon is largely due to the difficulty of carbon diffusion into its dense surface. It was found that the carburization rate was affected by change of surface conditions and surface area by reduction, degradation, and cracks at high temperature. This study should help provide a fundamental understanding of carburization in the field of iron-making and suggest a direction for its further development.
조병욱 ( Byong Wook Cho ),윤욱 ( Uk Yun ),이병대 ( Byeong Dae Lee ),송원경 ( Won Kyong Song ),황재홍 ( Jae Hong Hwang ),추창오 ( Chang Oh Choo ) 대한지질공학회 2011 지질공학 Vol.21 No.2
독도에서 지하수가 유일하게 산출되는 서도 물골 지하수의 유출 특성을 파악하기 위하여 지하수 충전 기구 해석, 5회의 유출량과 전기전도도(EC)를 측정하였다. 물골 지하수는 물골 상류에 내린 강수가 조면안산암와 조면암에 발달한 냉각절리를 따라서 하류로 이동하다가 물골의 동굴에 이르러 유출되는 것으로 해석된다. 물골 지하수의 유출량은 1.12~7.02 m3/d이고 EC는 2,650~3,390 μS/cm로 변화가 적은편이나 강수량이 많으면 일시적으로 EC가 상승한다. 이와 같은 물골 지하수의 유출량과 EC의 변화는 물골 상류 지하수 충전 지역과 물골과의 거리가 짧으며 조면안산암와 조면암에 발달한 주상절리를 통한 물골로의 지하수 흐름이 빠르기 때문으로 판단되나 물골 지하수의 유출량 변화 파악을 위해서는 추가 유출량조사와 함께 정확한 강수자료가 요구된다. The discharge characteristics of the Seodo Mulgol Spring-the only groundwater-producing area in Dokdo-were evaluated by measurements of discharge rate and electrical conductivity (EC) on five occasions. The Seodo Mulgol Spring is fed by rainfall in upstream areas of the Mulgol cave, and the rainwater of the area moves down along cooling joints developed in trachyandesite II and trachyte, finally discharging at the Mulgol cave. The discharge rate of the Seodo Mulgol Spring varied from 1.12 to 7.02 m3/d during the study period and EC varied from 2,650 to 3,390 μS/cm, showing a sharp increase during heavy rainfall. The observed variations in discharge rate and EC at the Seodo Mulgol Spring are attributed to the relatively short distance between the recharge area and the Mulgol cave, and to the rapid movement of groundwater through columnar joints developed in trachyandesite II and trachyte. Additional discharge measurements, combined with precise rainfall data, are required at Dokdo to elucidate the discharge characteristics of the Seodo Mulgol Spring.
Experimental Determination of the Optimum Blank Shape in Rectangular Cup Drawing
Bae, Won-Byong,Kim, Ho-Yoon,Hwang, Bum-Chul Korean Society for Precision Engineering 2003 International Journal of the Korean Society of Pre Vol.4 No.1
The rectangular deep drawing process is widely used in sheet metal forming, but there are various associated defects, such as earing, wrinkling, tearing, etc. In order to avoid such defects, an optimum blank shape is required. Such an optimum blank shape cannot be generalized because deep drawing processes are involved in complex process parameters. So, it is necessary to do systematic research to determine the optimum blank shape for the deep drawing process. In this study, a rectangular cup drawing test has been carried out to determine the optimum blank shape for various stainless steel sheets. From the test, a new blank model, which has no earing, is propsed.