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Evaluation of stress distribution with wind speed in a greenhouse structure
Deog-jae Hur,Jung-Hun Noh,Hyun ju Lee,Hyoung woon Song 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.5
In this paper, stress distribution for a structurally stable greenhouse is considered in the present paper with subsequent investigation into the detailed stress distribution contour with the variation of self-weight and wind pressure level designation method under wind velocity of less than 30 m/sec. For reliable analysis, wind pressure coefficients of a single greenhouse unit were modeled and compared with experiment with correlation coefficient greater than 0.99. Wind load level was designated twofold: direct mapping of fluid dynamic analysis and conversion of modeled results into wind pressure coefficients (CP). Finally, design criteria of EN1991-1-4 and NEN3859 were applied in terms of their wind pressure coefficients for comparison. CP of CFD result was low in the most of the modeled area but was high only in the first roof wind facing and the last lee facing areas. Besides, structural analysis results were similar in terms of stress distribution as per EN and direct mapping while NEN revealed higher level of stress for the last roof area. The maximum stress levels are arranged in decreasing order of mapping, EN, and NEN, generating 8% error observed between the EN and mapping results under 30 m/sec of wind velocity. On the other hand, effect of dead weight on the stress distribution was investigated via variation of high stress position with wind velocity, confirming shift of such position from the center to the forward head wind direction. The sensitivity of stress for wind velocity was less than 0.8% and negligible at wind velocity greater than 20 m/sec, thus eliminating self-weight effect.
Evaluation of stress distribution with wind speed in a greenhouse structure
Hur, Deog-jae,Noh, Jung-Hun,Lee, Hyun ju,Song, Hyoung woon Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.27 No.5
In this paper, stress distribution for a structurally stable greenhouse is considered in the present paper with subsequent investigation into the detailed stress distribution contour with the variation of self-weight and wind pressure level designation method under wind velocity of less than 30 m/sec. For reliable analysis, wind pressure coefficients of a single greenhouse unit were modeled and compared with experiment with correlation coefficient greater than 0.99. Wind load level was designated twofold: direct mapping of fluid dynamic analysis and conversion of modeled results into wind pressure coefficients ($C_P$). Finally, design criteria of EN1991-1-4 and NEN3859 were applied in terms of their wind pressure coefficients for comparison. $C_P$ of CFD result was low in the most of the modeled area but was high only in the first roof wind facing and the last lee facing areas. Besides, structural analysis results were similar in terms of stress distribution as per EN and direct mapping while NEN revealed higher level of stress for the last roof area. The maximum stress levels are arranged in decreasing order of mapping, EN, and NEN, generating 8% error observed between the EN and mapping results under 30 m/sec of wind velocity. On the other hand, effect of dead weight on the stress distribution was investigated via variation of high stress position with wind velocity, confirming shift of such position from the center to the forward head wind direction. The sensitivity of stress for wind velocity was less than 0.8% and negligible at wind velocity greater than 20 m/sec, thus eliminating self-weight effect.
Deog-jae Hur,Dong-chan Lee 한국자동차공학회 2004 한국자동차공학회 Symposium Vol.- No.-
This paper describes an application of optimization design using multilevel decomposition technique on the base of the parametric distribution and independent axiom at the stages of lower level. Based on Pareto optimum solution, the detailed parameters at the lower level can be defined into the independent axiom. And this technique is applied to develop the suspension of torsion beam axle. We have the very efficiency results that decision the characteristics of the geometric parameters and torsion beam section profile. In the comparison with the base model the maximum stress reduced by 18%, and roll steer and camber are improved by 6%.<br/>
도심교통소음의 노출시간에 따른 라우드니스 및 어노이언스의 주관적 반응에 대한 연구
허덕재(Hur, Deog-Jae),조경숙(Jo, Kyoung-Sook),최병호(Choe, Byong-Ho) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.3
A study has been conducted to investigate the subjective responses of loudness and annoyance according to the exposed time of urban traffic noise in controlled laboratory environment. To make a closer inspection into psychological response relevant to noise characteristics while varying the time of exposure to noise, the subjects were presented a set of noises with different exposed time and requested to judge spontaneously on a 100-unipolar scale. To be concrete, the subjects were exposed to noises being varied in time from 15 sec up to max. 1,200 sec for the controlled traffic noise sources. So far achieved from laborious tests, it has an importance being on the logarithmic relations of perceived loudness and exposed time, say, it is more increased the perceived loudness in the sorter exposed time than in the longer exposed time. However, the trend is said to be not effective for the case of annoyance. On the other hand, the subjective impressions on relative annoyance of noise is shown to be correlated with the noise characteristics such as loudness (sones), tonality and time with logarithmic scale, the product correlation moment being calculated as $R^{2}=0.99$. The variances to be explained for annoyance assessments through varying the time of exposure were ranged between 30 % and 50% for the exposed time, $27{\sim}37%$ for tonality, and $34{\sim}20%$ for loudness, respectively With these results, hopefully, it can be helpful for those who want to work out an experimental design for evaluating an environmental noise or to quantify any psychological dimensions found in annoyance assessments.
CAE를 이용한 대형 상용차 배기계의 구조적 특성에 관한 연구
허덕재(Deog-Jae Hur),김병곤(Byoung-Gon Kim),최석환(Seok-Hwan Choi) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this study. a CAE techinique is developed in order to identify and optimize the characteristics of a heavy truck exhaust system. Under the given three loading conditions. the strength is investigated through static stress analysis along with parameter optimization. The dynamic performance is also evaluated by modal analysis. For the simplification and idealization of bellows in F. E. model. three ways of modeling techique are attempted and the results are compared.<br/>
수평 착자형 액추에이터의 전자기력 성능 향상에 관한 연구
허덕재(Deog Jae Hur),이재혁(Jai Hyuk Lee),권상엽(Sang Youp Kwon),이성수(Sung Su Lee) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
This paper describes optimization design to improve the performance of bandwidth and the maximum acceleration of the linear AC vibrator with horizontal magnetization. The variable was set the electromagnetic force of the exciting force of the haptic vibrator. Optimization in horizontal magnetization design leads the maximum electromagnetic force when the permanent magnet and coil are centrally aligned. In addition, when increasing the width and height of magnet, the electromagnetic force has increased also. The final optimized design is applied with the parameter combination, and the electromagnetic force has risen about 81.4% compared to the previous model.