• Advances in concrete construction
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• 제17권1호
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• pp.27-36
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• 2024

Reinforced concrete (RC) flat slabs should be designed based on punching shear strength. As part of this study, machine learning (ML) algorithms were developed to accurately predict the punching shear strength of RC flat slabs without shear reinforcement. It is based on Bayesian optimization (BO), combined with four standard algorithms (Support vector regression, Decision trees, Random forests, Extreme gradient boosting) on 446 datasets that contain six design parameters. Furthermore, an analysis of feature importance is carried out by Shapley additive explanation (SHAP), in order to quantify the effect of design parameters on punching shear strength. According to the results, the BO method produces high prediction accuracy by selecting the optimal hyperparameters for each model. With R² = 0.985, MAE = 0.0155 MN, RMSE = 0.0244 MN, the BO-XGBoost model performed better than the original XGBoost prediction, which had R² = 0.917, MAE = 0.064 MN, RMSE = 0.121 MN in total dataset. Additionally, recommendations are provided on how to select factors that will influence punching shear resistance of RC flat slabs without shear reinforcement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.976-979
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• 2005

This paper is about the development of automatic FPC(flexible printed circuit) punching instrument for the improvement of working condition and cost saving. FPC is used to detect the contact position of keyboard and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2mm and the above. Because the punching operation Is done manually, the accuracy of the punching degree is varied with operator's condition. To improve this manual punch ing operation to the FPC, automatic FPC punching system is introduced. Test algorithms and programs showed good results to the designed automatic punching system and led to the increasement of productivity and huge cost down to law material like FPC by avoiding bad quality.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2430-2434
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• 2005

Automatic FPC punching instrument for the improvement of working condition and cost saving is introduced in this paper. FPC(flexible printed circuit) is used to detect the contact position of K/B and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2mm and the above. Because the punching operation is done manually, the accuracy of the punching degree is varied with operator's condition. Recently, The punching accuracy has deteriorated severely to the 2mm punching reference hall so that assembly of the K/B has hardly done. To improve this manual punching operation to the FPC, automatic FPC punching system is introduced. Precise mechanical parts like a 5-step stepping motor and ball screw mechanism are designed and tested and low cost PC camera is used for the sake of cost down instead of using high quality vision systems for the FA. 3D Mechanical design tool(Pro/E) is used to manage the exact tolerance circumstances and avoid design failures. Simulation is performed to make the complete vision based punching machine before assembly, and this procedure led to the manufacturing cost saving. As the image processing algorithms, dilation, erosion, and threshold calculation is applied to obtain an exact center position from the FPC print marks. These image processing algorithms made the original images having various noises have clean binary pixels which is easy to calculate the center position of print marks. Moment and Least square method are used to calculate the center position of objects. In this development circumstance, Moment method was superior to the Least square one at the calculation of speed and against noise. Main control panel is programmed by Visual C++ and graphical Active X for the whole management of vision based automatic punching machine. Operating modes like manual, calibration, and automatic mode are added to the main control panel for the compensation of bad FPC print conditions and mechanical tolerance occurring in the case of punch and die reassembly. Test algorithms and programs showed good results to the designed automatic punching system and led to the increase of productivity and huge cost down to law material like FPC by avoiding bad quality.

• 대한기계학회논문집
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• 제17권5호
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• pp.1183-1192
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• 1993

본 연구에서는 다음과 같은 두가지 관점에서 공구경로 최적화를 위한 기존 방 법의 문제점을 검토하고 이의 개선 방안을 제시하였다. 첫째, 기존의 공구경로 산출 방법에서는 고려되지 않는 공구대의 공구 장착 현황(turret configuration)이 최적화 과정에서 고려되어야 한다. 둘째로, 제작과 관련한 구속조건(manufacturing con- straints)이 최적화 과정에 직접 반영되어야 한다.

• 한국정밀공학회지
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• 제22권12호
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• pp.77-86
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• 2005

This paper is about the development of Automatic FPC(flexible printed circuit) punching instrument for the improvement of working condition and cost saving. FPC is used to detect the contact position of keyboard and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2mm and the above. Because the punching operation is done manually, The punching accuracy is varied with operator's condition. Recently, The punching accuracy has deteriorated severely to the 2mm punching reference hall so that assembly of the K/B has hardly done. To improve this manual punching operation to the FPC, automatic FPC punching system is introduced. Precise mechanical parts like a 5-step stepping motor and ball screw mechanism are designed and tested and low cost PC camera is used fur the sake of cost down instead of using high quality vision systems for the factory automation. Test algorithms and programs showed good results to the designed automatic punching system and led to the increasement of productivity and huge cost down to law material like FPC by avoiding bad quality.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.981-984
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• 2004

This paper is about the development of Automatic FPC punching instrument. FPC(flexible printed circuit) is used to detect the contact position of K/B and button like a cellular phone. Depending on the quality of the printed ink and position of reference punching point to the FPC, the resistance and current are varied to the malfunctioning values. The size of reference punching point is 2mm and the above. Because the punching operation is done manually, the accuracy of the punching degree is varied with operator's condition. Recently, The punching accuracy has deteriorated severely to the 2mm punching reference hall so that assembly of the K/B has hardly done. To improve this manual punching operation to the FPC, automatic FPC punching system is introduced. Precise mechanical parts like a 5-step stepping motor and ball screw mechanism are designed and tested and low cost PC camera is used for the sake of cost down instead of using high quality vision systems for the FA. Test algorithm shows good results to the designed automatic punching system.

• 농업생명과학연구
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• 제50권5호
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• pp.217-224
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• 2016

본 연구에서 개발된 자동천공기는 콩의 재식밀도를 고려한 비닐 천공능력이 작업주행속도 0.18-0.28m/s 조건에서 콩의 주간거리 0.20m, 0.25m, 0.30m에 대해 각각 320-500㎡/h, 260-400㎡/h, 210-330㎡/h의 범위로 나타났다. 천공율은 칼날과 지면간 30mm 거리에서 비닐이 100% 천공되었으며, 50mm 거리에서 원형칼날 16.7-25.2%, 사각칼날 33.0-42.3%, 육각칼날 54.5-100.0% 범위에서 천공되었다. 또한, 육각칼날 60°에서 비닐 절단면이 매끄럽고 부드러워 절단품질이 가장 우수하였다.

• 한국공작기계학회논문집
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• 제18권1호
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• pp.36-41
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• 2009

This paper presents the development of a micro punching system with modified cymbal mechanism. To realize the micro punching, we introduced the hybrid system with a macro moving part and micro punching part. The macro moving part consists of a ball screw, a linear guide and the micro step motor and micro punching part includes the PZT actuators and displacement amplification device with modified cymbal mechanism. The PZT actuator is capable of producing very large force, but they provide only limited displacements which are several micro meters. Thus the displacement amplification device is necessary to make those actuators more efficient and useful. For this purpose, a cymbal mechanism in series is proposed. The finite element method was used to design the cymbal mechanism and to analyze the mode shape of the one. The displacement and mode shape error between the FEM results and experiments are within 10%. A considerable design effort has been focused on optimizing the flexure hinge to increase the output displacement and punching force.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.434-438
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• 2003

The shearing process for the sheet metal is normally used in the precision elements such as semi-conductor components. In these precision elements, the burr formation brings a bad effect on the system assembly and demands the additional de-burring process. In this paper, we have developed the desktop-type precision punching system to investigate the burr formation mechanism and present kinematically Punch-die auto aligning methodology, for the purpose of burr unifomizing and minimizing, between the rectangular shaped punch and die. By using the scanning electron microscope, the aligned punching results are compared with the miss-aligned ones. Also, we measured the relative burr heights using the self-designed laser measuring device for insitu self aligning. Since it is hard to get the perfect, so called, burr-free edges during the shearing process, we introduced the ultrasonic do-burring machine. The de-burring operation was carried out by a novel do-burring method, the reversal flow resistance method, under different machining loads and abrasive types. The final do-burring results show the validity of our punching do-burring system pursuing the burr-free punched elements.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.61-67
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• 2004

In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. In this study, magnetic field-assisted polishing technique is applied to remove the burr which exists in nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals was investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.