• 제어로봇시스템학회논문지
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• 제21권8호
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• pp.723-728
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• 2015

In the conventional hot rolling process, the defects of products such as scratches occur due to impact and friction. Impact occurs as a result of the contact of between rollers and the slab. Also, friction occurs in the rolling process. To improve these defects, a variety of processes were developed. The flying touch method is also one of the processes to reduce defects and uses a movable upper roller. To use this unfixed roller, the impact and frictions between rollers and the slab should be minimized. This paper proposes a hot rolling process simulator to verify and test the efficiency of the flying touch method. The simulator was designed to verify the method. This paper also proposes a new impact reducing method and velocity synchronization method which are simulated to realize the method.

• 한국군사과학기술학회지
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• 제18권5호
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• pp.525-531
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• 2015

In this paper, a novel impact sensing device for an ESAF(Electronic Safe and Arming Fuze) is presented. An impact sensing device is mounted in front of a weapon, and it detects an impact when it crashes against a target. There are two main design requirements to enhance the firing functional reliability of the ESAF; an operational reliability and a reduced latency, which is a delay time needed for sensing the impact. The design method of the contact-type impact sensing device, which employs an FPCB(Flexible Printed Circuit Board) so it can be used other weapons, is proposed. The tests demonstrated that the design described in this work show a reduced delay time with ensuring the operational reliability.

• Journal of Advanced Research in Ocean Engineering
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• 제4권4호
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• pp.146-162
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• 2018

The unsteady problem of a rigid body impact onto a floating plate is studied. Both the plate and the water are at rest before impact. The plate motion is caused by the impact force transmitted to the plate through an elastic layer with viscous damping on the top of the plate. The hydrodynamic force is calculated by using the second-order model of plate impact by Iafrati and Korobkin (2011). The present study is concerned with the deceleration experienced by a rigid body during its collision with a floating object. The problem is studied also by a fully-nonlinear computational-fluid-dynamics method. The elastic layer is treated with a moving body-fitted grid, the impacting body with an immersed boundary method, and a discrete-element method is used for the contact-force model. The presence of the elastic layer between the impacting bod- ies may lead to multiple bouncing of them, if the bodies are relatively light, before their interaction is settled and they continue to penetrate together into the water. The present study is motivated by ship slamming in icy waters, and by the effect of ice conditions on conventional free-fall lifeboats.

• International Journal of Advanced Culture Technology
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• 제10권3호
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• pp.263-271
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• 2022

The purpose of this study is to identify the degree of participation and the impact of social media sports contact motivation on sports activities. In order to clarify the purpose of this study, a total of 300 students from 150 male and 150 female university students in Gwangju and Jeonnam provinces in 2020 were selected by the convenience sampling method. The survey tool used to achieve the purpose of this study is the questionnaire method. Therefore, the questionnaire, which has already been verified for reliability and validity in domestic and foreign previous studies, was re-quoted, modified, or supplemented for the purpose of this study. For data processing, SPSS Windows 20.0 Version was used. For specific statistical analysis, frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis were performed according to the purpose of analysis. The results obtained through these results are as follows. First, it was found that the contact motivation for social media sports partially affected the degree of participation in social media sports. Second, it was found that social media sports contact motivation has a partial influence on sports participation. Third, the degree of social media sports participation was found to have a partial influence on sports participation.

• 환경영향평가
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• 제18권2호
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• pp.79-87
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• 2009

This study was performed for the application of porous concrete blocks and aquatic plants for the water purification in small urban stream. This study investigated the ability of water purification according to various environments, algae and aquatic plants. When the porous concrete was used as contact media, the average removal efficiencies of SS, BOD and COD were 85~95%, 50~60% and 65~75%, respectively. Also, when the porous concrete and aquatic plants was used the average removal efficiency of SS, BOD and COD were 90~95%, 60~70% and 70~80%, respectively. As the results, average removal efficiency of total nitrogen, at the condition of the porous concrete and aquatic plants, was about 40-50%, then, that of total phosphorus was about 60-70%.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.734-739
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• 2003

When a train moves on rails, wheel and rail vibrate to produce contact noise and contact force. The former results in airborne noise and the latter transmits through bogie and excites carbody to generate structure borne noise. In this paper, wheel vibration is studied by theoretical and experimental approaches. Theoretical analysis is performed by finite element method and experimental analysis is performed by impact test. Using modal analysis and model tunning, we could have good agreement between the two approaches.

• 한국안전학회지
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• 제16권1호
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• pp.9-17
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• 2001

The purpose of this research is to analyze the impact resposes(impulsive stress and strain etc.) of anisotropic materials subjected to the low-velocity impact. For this purpose, a beam finite element program based on modified higher-order beam theory for anisotropic materials are developed and used to simulate the dynamic behaviors [contact force, displacement of ball and target, strain(stress) response histories] according to the changes of material property, stacking sequence, velocity and dimension etc.. Test materials for simulation are composed of $[0^{\circ}/45^{\circ}/0^{\circ}/-45^{\circ}/0^{\circ}]_{2s} and [90^{\circ}/45^{\circ}/90^{\circ}/-45^{\circ}/90^{\circ}]_{2s}$ stacking sequences. Finally, the results of this simulation are compared with those of wave propagation theory and then the impact responses and wave propagation phenomena are investigated.

• Structural Engineering and Mechanics
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• 제35권3호
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• pp.349-364
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• 2010

The impact behaviour and the impact-induced damage in laminated composite cylindrical shell subjected to transverse impact by a foreign object are studied using three-dimensional non-linear transient dynamic finite element formulation. A layered version of 20 noded hexahedral element incorporating geometrical non-linearity is developed based on total Langragian approach. Non-linear system of equations resulting from non-linear strain displacement relation and non-linear contact loading are solved using Newton-Raphson incremental-iterative method. Some example problems of graphite/epoxy cylindrical shell panels are considered with variation of impactor and laminate parameters and influence of geometrical non-linear effect on the impact response and the resulting damage is investigated.

• 대한기계학회논문집B
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• 제38권6호
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• pp.539-545
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• 2014

실리콘 태양전지의 실버 전극과 이미터층 사이의 접촉 비저항은 원형 접촉 비저항 측정법과 선형 비저항 측정법을 이용하여 계측되어 왔다. 원형 접촉 비저항 측정법은 누설 전류를 차단하기 위한 메사 에칭 등의 부가적인 공정이 요구되지 않는 장점이 있으며, 선형 접촉 비저항 측정법은 완성된 태양전지로부터 직접 샘플을 취득하여 측정을 수행할 수 있다는 장점이 있다. 본 연구에서는 이 두 가지 측정법들을 이용하여 실리콘 태양전지 전면 전극의 접촉 비저항을 계산하기 위한 저항값들을 측정할 때 수반되는 문제점들에 대한 비교연구를 수행하였으며, 선형 접촉 비저항 측정법이 실버 전극의 선폭과 두께에 따른 접촉 비저항 변화를 좀더 정확하게 묘사할 수 있는 요인에 대해 설명하였다.

• Composites Research
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• 제13권6호
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• pp.47-54
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• 2000

복합재 구조물의 저속충격탐지 방법 중의 하나는 고분자 압전센서를 이용하는 것이다. 본 논문에서는 저속충격을 받는 복합재 평판에 대한 충격력과 부착된 스트레인 게이지, 고분자 압전센서 신호와의 관계를 유도하였다. 압전센서의 등가회로도를 통해서 고분자 압전센서의 개회로 신호와 폐회로 신호와의 관계를 유도하여 전하증폭기를 사용하지 않은 고분자 압전센서 신호를 이용하여 복합재 평판의 충격력 복원 가능성에 대한 연구로 확장하였다. 진동실험을 통하여 얻은 복합재 평판의 고유진동수와 감쇠비를 이용하여 해석적인 모델을 수정하여 정방향 문제와 역방향 문제에 있어서 오차를 줄일 수 있었다. 복원된 충격력과 해석적인 센서 신호는 실제 저속 충격 실험을 통하여 측정한 충격력, 스트레인 게이지 신호, 그리고 고분자 압전센서 신호와 잘 일치하였다.