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사축식 유압 피스톤 펌프의 실린더블록 편심률에 따른 지연각의 특성 해석
정재연(Jaeyoun Jung),신현일(Hyunil Shin),백일현(Ilhyun Beak),조인성(Ihnsung Cho),송규근(Kyukeun Song),오석형(Seokhyung Oh),정용욱(YongWook Jeong) 한국트라이볼로지학회 2007 한국트라이볼로지학회 학술대회 Vol.2007 No.11
To improve the performance of the bent-axis type axial piston pump driven by the tapered piston, it is necessary to know the driving characteristics and mechanism of the tapered piston and the cylinder block. Since each piston not only rotates on its axis and reciprocates in the cylinder bore, but also revolves around the axis of the driving shaft, it is difficult to analyze the driving mechanism theoretically. The theoretical mechanism for the bent-axis type axial piston pump is studied by using the geometrical method. The driving range of the tapered piston is determined by theoretical equations. The results show that the cylinder block is driven by one tapered piston in a limited range and the core parameters such as driving factor of the piston and the ahead delay angle influenced performance of the bent-axis type axial piston pump
정재연(Jaeyoun Jung),신현일(Hyuni1 Shin),백일현(Ilhyun Beak),조인성(Ihnsung Cho),송규근(Kyukeun Song),오석형(Seokhyung Oh),정용욱(YongWook Jung) 한국트라이볼로지학회 2008 한국트라이볼로지학회 학술대회 Vol.2008 No.6
Recently, noise and vibration by roller bearing brings trouble to pass in need to more speedy rotating and light weight, high durability in rotating system. For distinction clearly of appropriateness of roller bearing element, the effect of total system necessaries sure understanding under the motion condition. But, although roller bearing is used extensively, the related researches in this field are extremely limited. Therefore, attempts have been made to calculate film thickness, pressure distribution throughout the analysis of elastohydrodynamic lubrication, and contribute to high efficiency and performance improvement of bent-axis type piston pump throughout the close examination of lubrication characteristics between roller and inner race of roller bearing in this paper.
정재연 ( Jae Yeon Jung ),임미희 ( Mi Hee Lim ) 한국치위생학회(구 한국치위생교육학회) 2015 한국치위생학회지 Vol.15 No.6
Objectives: The purpose of this study was to examine awareness and satisfaction toward health insurance coverage of scaling. Methods: A self-reported questionnaire was completed by 221 patients receiving scaling service from July to August, 2014. The informed consent was approved after the explanation of purpose of the study. The questionnaire consisted of general characteristics of the subjects, awareness toward health insurance coverage of scaling, scaling service covered by health insurance, and satisfaction with health insurance service. Results: Those recognizing the health insurance service extension accounted for 87.3 percent and 67.4 percent answered that the appropriate coverage age would be 20 years old. The recommendable frequency of scaling was once a year and this accounted for 49.3 percent. Fifty percent of the subjects thought health insurance coverage of scaling would be reasonable and 34.8 percent acquired the information from mass media. The most common service providers were dental hygienists and the length of service was from 20 to 30 minutes. The contents of service included scaling service, toothbrushing method, and oral care. The satisfaction was 4.39 points. Conclusions: The health insurance coverage of scaling will improve the oral health and quality of life in Korean adults. So the government should try to extend the scaling coverage by health insurance and the frequency of scaling.
국내외 보건용 마스크의 안면부 밀착도 및 누설률 비교: 마스크 디자인과 착용자 얼굴형을 고려한 탐색적 평가
정재연(Jae-Yeon Jung),이주영(Joo-Young Lee) 한국생활환경학회 2021 한국생활환경학회지 Vol.28 No.4
The purpose of the present study was to evaluate the fit factors and total inward leakage (TIL) of commercially-available face masks in Korea. We selected a total of six face masks: surgical, KF AD, KF80, KF94, KF99 and N95. Six male subjects participated in a fit test, while ten subjects participated in TIL test. Among the subjects, only three subjects participated in both tests and the relationship between fit factor and TIL was analyzed using data from the three subjects. The results showed that 1) no relationship between filtration of mass and fit factor was found, 2) greater filtration level, smaller TIL; 3) smaller fit factor, greater TIL (r=0.498, p<0.05). However, the correlation was not that great, which was attributed to the differences in mask design (folded or flat type vs. cup type; ear loop vs. head band) and face types. In order to minimize leakage rate when wearing face masks, a cup type with seal and head bands is recommended rather that folded types with ear loops. It needs that the fit test should be a mandatory test for hospitals or occupational fields where workers should wear their own face masks to protect then from dusts or biological hazards. Also, the development of Korean face test panel should be precedent to conduct a fit test.
사축식 피스톤 펌프의 피스톤 링과 실린더 보어간의 윤활특성에 관한 연구
정재연(JaeYoun Jung),조인성(IhnSung Cho),백일현(IlHyun Baek),손소화(ShaoHua Sun),신현일(Hyunil Shin),송규근(KyuKeun song),오석형(SeokHyung Oh) 한국트라이볼로지학회 2007 한국트라이볼로지학회 학술대회 Vol.2007 No.6
The bent-axis type piston pump which is driven by the piston rod works on the way that the piston rod drives the cylinder block, so the taper angle of the piston rod and the swivel angle between the cylinder block and the shaft are very important design factors. If the above factors cannot satisfy the conditions of optimum design, the friction loss between the cylinder bore and the piston increases, and the pump can even fail to work under conditions of severe friction and wear. Since the piston reciprocates in the cylinder bore with high velocity, and at the same time it rotates on its own axis and revolves on the center of the cylinder block, the decrease of the volume efficiency generated on account of the leakage between the cylinder bore and the piston. Therefore, to prevent this case, the piston ring is designed at the end of the piston, and the friction characteristics between the piston ring and the cylinder bore are in need of research due to its great influence on the performance of piston pump. Thus, in this paper, the elastic hydraulic oil’s lubrication analyses of the film thickness, the pressure distribution, and the friction force, and so on, have been performed, and the lubrication characteristics between the piston ring and the cylinder bore are explored by the results of the numerical analysis, and it is contributed to realize the higher efficiency and the more advanced performance of the bent-axis type piston pump.
정재연 ( Jae Yeon Jung ),한수진 ( Su Jin Han ) 한국치위생과학회 2011 치위생과학회지 Vol.11 No.6
The purpose of this study was to examine elderly people`s oral health behaviors and education needs. The subjects in this study were 195 senior citizens who were users of senior cultural centers and senior welfare agencies in Seoul and Incheon. After a survey was conducted, the collected data were analyzed by the statistical package SPSSWIN 19.0. The findings of the study were as follows: 1. Gender, academic credential and monthly mean income were identified as the general characteristics to impact on their oral health attitude. 2. The senior citizens who ever received oral health education had a better knowledge(p<0.05) and took a better attitude(p<0.01). 3. As for a time for toothbrushing, many brushed their teeth after breakfast(74.9%) and dinner(71.8%). Utilized Oral hygiene devices were interdental brushes(21.5%), dental floss(13.8%). As many as 62.5% felt they had a dry mouth, and the most prevalent way for them to cope with it was drinking water often(68.2%). 79.5% didn`t get their teeth cleaned on a regular scaling. 4. The rate of regular scaling was higher in the elderly groups that ever received oral health education and whose knowledge scores was above the average(p<0.05). 5. In relation to the necessity of oral health education, 87.2% felt the need for that, and as many as 79.0% intended to receive that education. Their favorite period of education was 6months(41.0%), and the greatest group hoped to receive that education for an hour(55.4%). The largest group wanted to learn about prevention of oral diseases, followed by toothbrushing, denture management, dry mouth. Given the findings of the study, senior welfare centers and senior cultural centers should offer oral health education programs as part of lifelong education to provide systematic and prolonged education for the elderly to improve their oral health care to promote their oral health.
정재연(Jae-Youn Jung),백일현(Il-Hyun Baek),오석형(Seok-Hyung Oh),김신(Shin Kim) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The aerial working platform has three motion axes, that is, telescoping, elevation and slewing, which arc driven by electro-hydraulic actuators. Generally the operation of the aerial working platform is difficult because of nonlinear characteristics of hydraulic actuators and its complicated mechanical structures. Especially the telescopic boom operations involve stick-slip oscillations like slideways and the shape of stick-slip becomes more severe and saw-toothed.<br/> The purpose of this study is to derive the experimental model for the system of the telescopic boom in the stick-slip condition. From this theoretical approach, we obviously found stick-slip oscillations, when hydraulic telescopic booms taken large mass are driven at slow speeds between the two pads.<br/>