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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.
New Development of Hexahedral Type Vibration Motor Used for Mobile Phones
Hwang, Gun-Yong,Hwang, Sang-Moon,Chung, Shi-Uk,Kang, Beom-Soo,Hwang, I-Cheol The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.8
Mobile communication industry powered by electronics and information technology is building a transforming way for human communication. The latest electronics is so saturated to forget the difficulty in size reduction of electronic parts. However, mechanical parts, such as dynamic speakers and vibration motors, are intrinsically not easy to realize size reduction due to their construction. In this paper, a hexahedral type with simpler configuration is introduced to substitute for the conventional vibration motors. For uneven magnetic field analysis of the hexahedral type, FEM was used to determine magnetic flux density. After an analysis of magnetic and mechanical characteristics, it is shown that the coil configuration is the most important parameter to increase the output torque, and thus vibration. For optimization, genetic algorithm is used to find the optimal configuration of coil to maximize the output torque. Experimental results are also followed to confirm the validity of the proposed design.
황범철(Hwang Beom-Cheol),허진영(Huh Jin-Young),임현묵(Lim Hyun-Muk) 한국체육과학회 2010 한국체육과학회지 Vol.19 No.4
The purpose of this study was to identify the casual relationship among self-efficacy, social support, type of career decision-making, and career decision-making attitude for students majoring TaeKwonDo. Subjects (N=630) were selected from 23 different universities by using the convenience sampling technique. The data were recorded and analyzed using the AMOS 7.0 statistical computer package to do an EFA and SEM. The results from EFA and Structural Equation Model are followed. First, self-control efficacy has significantly influenced on social support. Second, self-confidence has significantly effect on career decision-making. Third, emotional and appraisal support has influenced on career maturity while information support has influenced on career preparation behavior. Fourth, intuitional type of career decision has significantly influenced on the level of career decision-making and career maturity, but the rational type have significantly influenced on the career preparation behavior. Overall, self-control efficacy which is sub factor for self-efficacy is a variable that has influenced on career decision-making attitude through social support and type of career decision-making. Therefore, this study indicated that when TaeKownDo major students perceive their social support as an important support source, students may have more effort for rationally career decision-making with self-confidence.
슬리브 스프링 형식 비틀림 진동감쇠기 제조를 위한 공정해석 및 시험
황법철(Beom Cheol Hwang),배원병(Won Byong Bae),장영준(Young Jun Jang),김철(Chul Kim) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.12
In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, the closed form equations to predict the spring constant of a sleeve spring and the torsional characteristics of the torsional vibration damper are proposed to calculate stiffness of the damper and verified their availability through the finite element analysis and experiments. And the stability of the sleeve spring torsional vibration damper is verified by analyzing the inner star and outer star, which are the core parts of the damper, and 2-roll bending process is proposed to manufacture sleeve spring. The program to calculate the initial radius including spring-back effect is developed, and the FEA method to analyze elasto-plastic problem was verified through analysis of 90°bending process. The results of the analysis are in good agreements with those of the experiments. The newly proposed method can be used as an advanced technique that remarkably curtails cost of production and replaces the conventional forming.
New Development of Hexahedral Type Vibration Motor Used for Mobile Phones
Gun-Yong Hwang,Sang-Moon Hwang,Shi-Uk Chung,Beom-Soo Kang,I-Cheol Hwang 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.8
Mobile communication industry powered by electronics and information technology is building a transforming way for human communication. The latest electronics is so saturated to forget the difficulty in size reduction of electronic parts. However, mechanical parts, such as dynamic speakers and vibration motors, are intrinsically not easy to realize size reduction due to their construction. In this paper, a hexahedral type with simpler configuration is introduced to substitute for the conventional vibration motors. For uneven magnetic field analysis of the hexahedral type, FEM was used to determine magnetic flux density. After an analysis of magnetic and mechanical characteristics, it is shown that the coil configuration is the most important parameter to increase the output torque, and thus vibration. For optimization, genetic algorithm is used to find the optimal configuration of coil to maximize the output torque. Experimental results are also followed to confirm the validity of the proposed design.<br/>
Hwang, Ki-Jun,Kim, Ho-Seok,Han, In-Cheol,Kim, Beom-Tae Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.8
A series of heterocyclic chalcone derivatives bearing heterocycles such as thiophene or furan ring as an isostere of benzene ring were carefully prepared, and the influence of heterocycles on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities was systematically investigated. Structure-activity relationships (SAR) analysis showed that the activities of thiophene ring-containing chalcones were higher than those of furan ring-containing chalcones, and the presence of methyl substituent of heterocyclic ring distinctly affected the activities compared with non-substituted heterocycles in an opposite manner, with the 4'-methyl group of thiophene ring increasing activity and the 3'-methyl group of the furan ring decreasing activity. The distinct isosteric effect of heterocycles (i.e., thiophene or furan ring) on radical scavenging activities of heterocyclic chalones was distinctly demonstrated in our work.