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리진철(Zhen-Zhe Li),이재우(Jae-Woo Lee),이창진(Chang-Jin Lee),최인석(In-Seok Choi) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Optimization study has been carried out to design an energy efficient, high temperature vacuum furnace which satisfies users' design requirements. First of all, the unsteady temperature distribution and the working zone results have been compared with the steady state results to validate the suitability of using steady state results when constructing the thermal analysis DB. In order to check the accuracy of the constructed thermal analysis DB, the interpolated results using constructed thermal analysis DB have been compared with computational results and experimental results. For this design problem, total heat flux is selected as the objective function, and the geometry of vacuum furnace including thickness of insulator, heat zone sizes and the interval between heater and insulator are the design variables, and the working zone sizes and the wall temperature are imposed as the design constraints. Finally, with negligible computational cost a high temperature vacuum furnace whick has 40~60% reduction in the total heat flux is designed using constructed thermal analysis DB.
리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Thermoforming is one of the most versatile and economical process to produce polymer products. The drawback of thermoforming is difficult to control thickness of final products. Temperature distribution affects the thickness distribution of final products. At first, it was found out that time-dependent variation of heat affects to the temperature difference. Analytic solution was studied because optimization time is remarkably large when optimal design is directly carried out using analysis code developed in previous study. Duhamel's theorem was used in order to solve l-D heat conduction with time-dependent boundary condition. 8 Optimal cases was carried out using the developed analytic solution. In the following step, an exponential function was recommended to present time-dependent heat flux through analyzing the results of the optimal cases. Finally, it was verified that temperature difference can be remarkably minimized by using the exponential function as a input data.
리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),최준호(Choi Jun-Hoo),설승윤(Seol Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Thermoforming is one of the most versatile and economical process to produce polymer products. The drawback of thermoforming is difficult to control thickness of final products. Temperature distribution affects the thickness distribution of final products. At first, Duhamel's theorem was used in order to get analytic solution, but the analytic solution was difficult to be applied when the boundary condition is complicate or noncontinuous. In order to compensate the drawback of analytic solution, the solution was found out using integral method. With checking the accuracy, it was found out that 4<SUP>th</SUP> order polynomial was fit to present time-dependent temperature profile in the direction of sheet thickness. Finally, case study was carried out using developed approximate analytic solution under the condition of satisfying requirements of thermoforming.
리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),최준호(Choi Jun-Hoo),설승윤(Seol Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Steam generation mechanism is the key technology of domestic steam cleaner. Not only weight and price of steam cleaner but also the performance of steam generation mechanism must be considered to improve the competitive power of the products. In order to find out the mechanism which can be used to improve the performance of steam generator, the process of steam generation was studied at first. In the following step, possibility of control, safety of mechanism and etc were compared about the two candidated steam generation mechanism. Finally, the merit and drawback of each mechanism were summarized.
열성형 과정에서 반응면 기법을 이용한 히터의 비정상 최적제어에 관한 연구
리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Thermoforming is one of the most versatile and economical processes available for the manufacturing polymer products. The drawback of thermoforming is difficult to get uniform thickness of final products. For the distribution of thickness strongly depends on the temperature distribution of sheet, the adjustment of heater power is very important In this paper, an optimization study for getting uniform temperature distribution was carried out using dual optimization steps. At first, the steady state optimal distribution of heater power is searched by numerical optimization to get uniform temperature of sheet surface. In the second step, time-dependent optimal heater inputs have been found out to decrease the temperature difference through the direction of thickness using Rseponse Surface Method and D-optimal method. The optimization results show that the time-dependent optimal heater power distribution gives acceptable uniform sheet temperature in the field of forming temperature.
리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Thermoforming is one of the most versatile and economical processes available for polymer products. In this study, water spray cooling was used instead of compressed air cooling in order to shorten the cycle time and reduce the cost of compressed air used in cooling process. At first, cooling time using compressed air cooling was predicted in order to check the state of mass production. The ratio of removed energy by compressed air cooling or water spray cooling among the total removed energy was found out in the following step. Finally, the analysis conditions suitable for cooling systems of thermoforming was found out by developed 1-D simulation code. The results using water spray cooling show that cycle time can be reduced because of high cooling efficiency of water spray, and cost of production and noise caused by using compressed air can be reduced by decreasing the amount of the used compressed air.
리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),최준호(Choi Jun-Hoo),설승윤(Seon Seoung-Yun) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
The steam generation mechanism is the key technology of domestic steam cleaner. Not only weight and price of steam cleaner but also the performance of steam generation mechanism must be considered to improve the competitive power of the product. In order to satisfy safety of the product, double insulated cartridge heater must be used, but it will decrease the performance of steam generator. In order to decrease the cost of final product, a steam generator using double insulated cartridge heater was designed at first before manufacturing. COMSOL which is one of the multi physics commercial code based on FEM was used to find out warm-up time and temperatue distribution. Finally, the possibility of control was simulated using ON/OFF control.
CFD와 입자추적기법을 이용한 카펫용 Upright 청소기이 집진효율 해석
최준호(Choe Jun-Ho),리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),장인형(Jang In-Hyeong),설승윤(Seol Seung Yun) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The drawbacks of carpet upright cleaner are low cleaning efficiency and noise. In order to estimate the cleaning efficiency and pressure drop of carpet upright cleaner, CFD and Particle Tracking Method are used. Using the developed method, the effect of rotational speed was investigated. Through the case studies, it was found out that the cleaning efficiency of carpet upright cleaner can be improved by adjusting rotational speed. Also, the trend of pressure drop and cleaning efficiency of each particle size were discussed. The analysis method developed in this study shows the possibility to improve the cleaning efficiency of carpet upright cleaner by adjusting the interrelated design variables.
CFD와 입자추적기법을 이용한 카펫용 Upright 청소기의 집진효율 해석
최준호(Choe Jun-Ho),리진철(Li Zhen-Zhe),허광수(Heo Kwang-Su),장인형(Jang In-Hyeong),설승윤(Seol Seung-Yun) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The drawbacks of carpet upright cleaner are low cleaning efficiency and noise. In order to estimate the cleaning efficiency of carpet upright cleaner, CFD and Particle Tracking Method are used. Using the developed method, the effect of rotational speed and wall shape was investigated. Through the case studies, it was found out that the cleaning efficiency of carpet upright cleaner can be improved by adjusting rotational speed and wall shape. The analysis method developed in this study shows the possibility to improve the cleaning efficiency of carpet upright cleaner by adjusting the interrelated design variables.
연속적인 곡선으로 정의 되는 볼록한 형상의 사이클론에 대한 연구
허광수(Heo Kwang-Su),설승윤(Seol Seoung-Yun),리진철(Li Zhen-Zhe) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
A cyclone design concept named Convex cyclone was developed to reduce pressure losses. Contrary to conventional cylinder-on-con type cyclone, inner wall of Convex cyclone are defined with a continuous curve and it has convex shape body. The discontinuity of inner diameter variation rate of cylinder-on-con type cyclone cause additional pressure loss. Continuous wall of Convex cyclone prevent additional pressure loss. In order to verify Convex cyclone design concept, we make a comparative experiments between Stairmand HE and Convex cyclone. Experimental Convex cyclone designed based on Stairmand HE model, and inner wall are defined with circular arch. The experimental result clearly shows that Convex cyclone can achieve maximum 50% pressure loss reduction with a few percent of collection efficiency drop. In addition, the experimental results indicated the existence of optimum convexity, minimum pressure loss, of cyclone wall.