http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Jeongbae Kim(김정배),Hee Youl Kwak(곽희열) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Parametric experiments for evaluating the performance of two fresh water generators applied plate type and shell & tube type heat exchangers were performed in this study. The test facility for the performance tests was designed and manufactured. The maximum fresh water yield of two fresh water generators applied in this study was designed as 1.5 Ton/day. The parameters relating with the performance of fresh water generator are known as sea water inlet temperature, hot water inlet temperature, and hot water flow rate. The test ranges for each parameters were 10, 20, and 30 ℃ for sea water inlet temperature, 65, 75, and 85 ℃ for hot water inlet temperature, 2.0, 2.5, and 3.0 m3/hr for hot water inlet volume flow rate, respectively. And the experiments to reveal the accuracy of experimental apparatus and to show the repeatability and reproducibility were also performed. The quantitative analysis for the heat transfer mechanism and mass balance under physically possible assumptions is also conducted with simple thermodynamic equations for both generators. The experimental and estimated quantities were compared. Through the experiments and simple analysis, this study firstly showed detail operation characteristics of fresh water generators with plate type and shell & tube type heat exchanger and compared the performance characteristics of two fresh water generators.
An analytical study on the thermal characteristics of flat-plate and evacuated solar collectors
Jeongbae Kim,Hee Youl Kwak,Dong Won Lee 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.12
In this study, we highlighted differences in the standards used in performance tests of solar collectors. We analyzed testing results for different types of solar collectors to determine the effects of the collector area and mass flow rate, which were not necessarily consistent across all tests. Our analysis showed that the factor, F′ (τα), including collector efficiency factor (F′), could be correlated with the flow rate or area regardless of the collector type. Moreover, the collector loss coefficient (F′UL) per flow rate or area for an evacuated collector was less that of a flat-plate collector; this was also correlated with the flow rate or area, regardless of the type of evacuated collector. As a result of this analysis, we propose a modified heat loss coefficient that includes the effects of all parameters that can be considered in a performance test and show that this coefficient could better describe the thermal characteristics of various types of solar collectors.
Instructor factors associated with medical students’ lecture evaluation: a longitudinal analysis
Jeongbae Rhie,Yoo-Mi Chae,Seok Gun Park,Jae-hyun Kim,Hong Ja Kim 한국의학교육학회 2023 Korean journal of medical education Vol.35 No.2
Purpose: This study identified factors that affect lecture evaluation by analyzing sophomores from Dankook University, examining each cluster’s characteristics, and comparing differences among trajectories. Methods: This study identified factors that affect lecture evaluation by analyzing sophomores from Dankook University, examining each cluster’s characteristics, and comparing differences among trajectories. Results: The lecture evaluation score decreased as the teaching hours per instructor in a year increased by an hour, and the number of instructors per lecture increased by one individual. During trajectory analysis, the first trajectory had lower lecture evaluation scores overall but relatively high appropriateness of the textbook and punctuality of class, whereas the second trajectory had higher lecture evaluation scores overall for all four items. Conclusion: The two trajectories showed differences in teaching methods (understanding of lecture content and usefulness of the lecture) rather than in external factors (appropriateness of the textbook and punctuality of class). Therefore, to improve lecture satisfaction, enhancing instructors’ instructional competencies through lectures and adjusting the teaching hours by assigning an adequate number of instructors per lecture are recommended.
On the Growth Behavior of Bubble during Saturated Nucleate Pool Boiling at Sub-atmospheric Pressure
Jeongbae Kim(김정배),Moo Hwan Kim(김무환) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Nucleate pool boiling analysis was performed using previous experimental results obtained with subatmospheric pressure and previous analytical results proposed by authors of this paper. To reveal the differences between the bubble growth behavior of atmospheric pressure and that of sub-atmospheric pressure is the main objective. The second is to show the effect of the system pressure on the bubble growth behavior. To do so, we correlated experimental data using the non-dimensional parameters of the characteristic radius and time scales proposed by previous study, and found that the growth behavior at sub-atmospheric pressure was basically different from that at atmospheric pressure during saturated nucleate pool boiling.
Experimental Study of Heating Surface Angle Effects on Single Bubble Growth
Jeongbae Kim,Hyung Dae Kim,Jangho Lee,Young Chul Kwon,Jeong Hoon Kim,Moo Hwan Kim 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.11
Nucleate pool boiling experiments were performed using pure R11 for various surface angles under constant heat flux conditions during saturated pool boiling. A 1-㎜-diameter circular heater with an artificial cavity in the center that was fabricated using a MEMS technique and a high-speed controller were used to maintain the constant heat flux. Bubble growth images were taken at 5000 frames per second using a high-speed CCD camera. The bubble geometry was obtained from the captured bubble images. The effects of the surface angle on the bubble growth behavior were analyzed for the initial and thermal growth regions using dimensional scales. The parameters that affected the bubble growth behavior were the bubble radius, bubble growth rate, sliding velocity, bubble shape, and advancing and receding contact angles. These phenomena require further analysis for various surface angles and the obtained constant heat flux data provide a good foundation for such future work.
Experimental Study on Heating Surface Angle Effects for Single Bubble Growth
Jeongbae Kim(김정배),Hyung Dae Kim(김형대),Moo Hwan Kim(김무환) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Nucleate pool boiling experiments with constant heat flux condition were performed using pure R11 for various surface angles under saturated pool condition. A circular heater of 1 mm diameter, with artificial cavity in the center, fabricated using MEMS technique and the high speed controller were used to maintain the constant heat flux. Images of bubble growth were taken at 5,000 frames per second using a high-speed CCD camera. The bubble geometry was obtained from the captured bubble images. The effects of surface angles on the bubble growth behaviors were analyzed as dimensional scales for the initial and thermal growth regions. The parameters on the bubble growth behaviors were bubble radius, bubble growth rate, sliding velocity, bubble shape and advancing and receding contact angles. These phenomena require further analysis for various surface angles, but this study will provide good experimental data with constant heat flux boundary condition for such works.
Jeongbae Kim,Jangho Lee,Moo Hwan Kim 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.5
Nucleate pool boiling experiments with constant wall temperature were performed using pure R113 for subcooled, saturated, and superheated pool conditions. A microscale heater array and Wheatstone bridge circuits were used to maintain the constant wall temperature and to measure the instantaneous heat flow rate accurately with high temporal and spatial resolutions. Images of bubble growth were taken at 5,000 frames per second using a high-speed CCD camera synchronized with the heat flow rate measurements. The bubble geometry was obtained from the captured bubble images. The effect of the pool conditions on the bubble growth behavior was analyzed using dimensionless parameters for the initial and thermal growth regions. The effect of the pool conditions on the heat flow rate behavior was also examined. This study will provide good experimental data with precise constant wall temperature boundary condition for such works.