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모터구동 글로브밸브의 Side Flow에 의한 디스크 - 몸체 마찰부하 평가
정래혁(Rae-Hyuck Jeoung),박성근(Sung-Keun Park),이도환(Do-Hwan Lee),송석윤(Seok-Yoon Song),강신철(Shin-Cheul Kang) 한국유체기계학회 2003 유체기계 연구개발 발표회 논문집 Vol.- No.-
EPRI PPM (Performance Prediction Methodology), a method used for the prediction of required thrust of valves, can not be applied to unbalanced-disk globe valves operated in the fluid when the fluid temperature is above 150˚F because the thrust increase caused by the friction between the valve disk and body is not considered in the PPM. In order to apply PPM to the valves, EPRI suggested new friction prediction method to be added in the code. This paper analyzes the applicability of the prediction method comparing the disk-to-body friction load predicted from the method with the measured friction load from the field tests. The maximum values from the prediction method and those obtained from the test were 268lbs and about 1500lbs, respectively. It is included that the prediction method should be improved for the realistic prediction of disk-to-body friction load.
정래혁 ( Rae Hyuck Jeoung ),이병곤 ( Byung Kon Lee ) 한국안전학회(구-한국산업안전학회) 2012 한국안전학회지 Vol.27 No.3
Mechanical seals are one of main components of high speed centrifugal pumps. So, it is very important to detect the faults (scratch, notch, indentation, wear) of mechanical seals since the damage of seal can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the seal fault using the time signals measured from sensors. Recently, studies are focused on the development of on-line real time monitoring system. But study on the feature parameters used for fault detection of mechanical seals has a little been performed. In this paper, we showed feature parameters extracted from accelerated and acoustic signals by using the discrete wavelet transform (DWT), alpha coefficient, statistical parameters. And also verified the possibility for fault detection of mechanical seal
다문화가정의 코로나19로 인한 가정경제 악화가 청소년 자녀의 불안에 미치는 영향과 일상생활 스트레스의 매개효과
이래혁 ( Rae-hyuck Lee ),이재경 ( Jae-kyoung Lee ) 한국아동가족복지학회 2022 한국가족복지학 Vol.27 No.2
Objective: This study was conducted with the purpose of examining the influence of family economic deterioration caused by COVID-19 on anxiety among adolescents in multicultural families as well as the mediating effect of daily stress. Methods: Data from the Korea Youth Risk Behavior Web-based Survey in 2020 were utilized, along with SPSS Process macro to analyze the direct and indirect influences of family economic deterioration caused by COVID-19 on anxiety. Results: First, the results show that family economic deterioration caused by COVID-19 positively and significantly influenced anxiety among adolescents in multicultural families. Next, adolescents’ daily stress fully mediated the influence of family economic deterioration caused by COVID-19 on anxiety. Experiencing family economic deterioration increased levels of daily stress and, in turn, increased the likelihood of experiencing anxiety. Conclusion: Based on the results, this study discussed social welfare intervention strategies to protect and improve the mental health of adolescents in multicultural families in the midst of a disaster.
A Study on the Stem Coefficient of Friction of Motor- operated Gate/Globe halves
Jeoung, Rae-Hyuck,Park, Sung-Keun,Lee, Do-Hwan,Kim, Yang-Seok Korean Nuclear Society 2003 Nuclear Engineering and Technology Vol.35 No.2
Stem-stem nut coefficient of friction(COF) in motor-operated gate/globe valves is one of the important factors which determine the performance of the valve/actuators. The COF is affected greatly by the type and condition of the stem-stem nut lubricants, environmental parameters, surface condition of the stem/stem-nuts, and the number of strokes after the lubrication. In this paper, the measured data of the COFs at stem threads of some safety-related motor-operated gate/globe valves in domestic nuclear power plants are presented. In addition, the performance of the lubricants is evaluated by comparing the COFs among those valves. The results show that the measured COF at torque switch trip are higher than the unwedging COF and conservatively applicable to the unwedging COF. It is also shown that the lubricating performance based on the measured COFs varies with the lubricants.