• Steel and Composite Structures
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• 제24권3호
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• pp.351-358
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• 2017

Due to the increasing competition, automotive manufacturers have to manufacture highly safe and light vehicles. The parts which make up the body of the vehicle and absorb the energy in case of a crash, are usually manufactured with sheet metal forming methods such as deep drawing, bending, trimming and spinning. The part may get thinner, thicker, folded, teared, wrinkled and spring back based on the manufacturing conditions during manufacturing and the type of application methods. Transferring these effects which originate from the forming process to the crash simulations that are performed for vehicle safety simulations, makes accurate and reliable results possible. As a part of this study, firstly, the one-step and incremental sheet metal forming analysis (deep drawing + trimming + spring back) of vehicle front bumper beam and crash boxes were conducted. Then, crash performances for cases with and without the effects of sheet metal forming were assessed in the crash analysis of vehicle front bumper beam and crash box. It was detected that the parts absorbed 12.89% more energy in total in cases where the effect of the forming process was included. It was revealed that forming history has a significant effect on the crash performance of the vehicle parts.

• 동력기계공학회지
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• 제19권3호
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• pp.75-80
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• 2015

Typically, robot system configured by articulated robot manipulator with 1 DOF transfer unit is being applied in automotive manufacturing automation process. Especially, 1 DOF transfer unit is necessary to extend workspace of robot manipulator. In this configuration, because transfer unit works only one direction, robot manipulator only works in one side in case of car body painting or sealing automation process. it is necessary three robot manipulator system at least. In this paper, in order to robot manipulator works effectively in car body sealing automation application, we are suggested omni-directional manipulator system and conducted studying on redundancy resolution method to solve manipulability-optimal problem.

• 한국기계가공학회지
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• 제21권4호
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• pp.60-69
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• 2022

To keep pace with Industry 4.0, it is imperative for companies to redesign their working environments by adopting robotic automation systems. Automation lines are facilitating the latest cutting-edge technologies, such as 3D vision and industrial robots, to outdo competitors by reducing costs. Considering the nature of the manufacturing industry, a time-saving workflow and smooth linkwork between processes is vital. At Dellics, without any additional new installation in the automation lines, only a few improvements to the working process could raise productivity. Three requirements are the development of gripping technology by utilizing a 3D vision system for the recognition of the material shape and location, research on lighting projectors to target long distances and high illumination, and testing of algorithms/software to improve measurement accuracy and identify products. With some of the functional requisites mentioned above, improved robotic automation systems should provide an improved working environment to maximize overall production efficiency. In this article, the ways in which such a system can become the groundwork for establishing an unmanned working infrastructure are discussed.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.142-151
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• 2005

To predict the fatigue life of the Hub Bearing Unit(HBU), preload effect and initial axial clearance have to be considered. Various theory and equations for the HBU design used in the passenger car are well developed in many literatures. But most design hand book for bearings or bearing catalogues do not consider the initial axial clearance and preload effect. So there are limits and difficulties to use those data in actual bearing design. To consider the preload effect and initial axial clearance, complex elliptic integrals and nonlinear equations are involved. These equations are difficult to solve during the design process. In order to solve these problems effectively, a program is developed to solve these equations reliably and to help the designer in obtaining the performance data of the HBU such as load distribution, maximum contact stress and fatigue life. The preprocessor of the program helps users to prepare the input data through a dialog box and the post processor makes graphical presentation of the result. In this paper, theoretical and numerical background for the prediction of the fatigue life of the HBU is explained. A simple example is presented to show the usefulness of developed program.

• 접착 및 계면
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• 제12권3호
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• pp.81-87
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• 2011

본 연구에서는 자동차 조립공정에 적용 할 수 있는 아크릴폼테이프를 합성하기 위하여 UV 중합 및 가교 공정을 도입하였다. 중합된 점착제를 폼에 합지하고 폼의 두께를 변화시켜 가며 시험편을 제조하였다. 기본물성을 측정하기 위해 stainless steel 표면에서의 강도를 측정하였으며 이때 peel, dynamic shear and t-block을 사용하였다. 일반적인 점착제에 비해 우수한 결과를 보여 주었으며 외부 요인 - 두께, 젖음시간 - 등에 의해 물성이 크게 변화하는 것을 확인 할 수 있었다. 본 연구에 활용된 아크릴폼점착제의 자동차 공정 활용성을 평가하기 위해 다양한 플라스틱 피착제에서 물성 측정을 진행하였다. 저표면에너지그룹으로 분류되는 PP와 PE에서는 그 물성이 전혀 발현되지 못했으나 기작 차이에 의해 dynamic shear 시험에서는 일부 물성이 발현됨을 확인 할 수 있었다.

• 한국화재소방학회논문지
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• 제33권5호
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• pp.7-12
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• 2019

목재 연료의 연소 시 생성되는 탄화가 열분해 과정에 미치는 영향을 고찰해 보기 위해서 ISO 5660-1 콘칼로리미터 실험을 수행하였고 Fire dynamics simulator (FDS) 전산해석 결과와 비교 분석하였다. 목재 연료로는 건축자재, 가구재 등에 대표적으로 사용되는 Douglas-fir를 사용하였다. Douglas-fir 연소 시 측정된 열방출률은 FDS 전산해석을 통해 예측한 결과와 비교적 잘 일치하였지만 탄화 층의 표면반응을 고려하지 않는 FDS 전산해석 모델은 훈소과정에서 지속적으로 방출되는 열을 예측하지 못하였다. 그럼에도 불구하고 FDS 전산해석을 통해 탄화 층은 가연물에 열장벽을 형성하여 내부로의 열전달을 방해하고 열적 두께를 두껍게 하여 열분해율을 감소시키는 것을 확인하였다.

• 한국기계가공학회지
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• 제11권6호
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• pp.130-138
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• 2012

There are increasing demands from the industry for intelligent robot-calibration solutions, which can be tightly integrated to the manufacturing process. A proposed solution can simplify conventional robot-calibration and teaching methods without tedious procedures and lengthy training time. iGPS(Indoor GPS) system is a laser based real-time dynamic tracking/measurement system. The key element is acquiring and reporting three-dimensional(3D) information, which can be accomplished as an integrated system or as manual contact based measurements by a user. A 3D probe is introduced as the user holds the probe in his hand and moves the probe tip over the object. The X, Y, and Z coordinates of the probe tip are measured in real-time with high accuracy. In this paper, a new approach of robot-calibration and teaching system is introduced by implementing a 3D measurement system for measuring and tracking an object with motions in up to six degrees of freedom. The general concept and kinematics of the metrology system as well as the derivations of an error budget for the general device are described. Several experimental results of geometry and its related error identification for an easy compensation / teaching method on an industrial robot will also be included.

• 한국응용과학기술학회지
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• 제29권3호
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• pp.450-458
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• 2012

최근 정부는 국가 온실가스를 효율적으로 감축시켜 국제적인 기후변화에 대응하기 위하여 여러 부문에서 기술개발을 진행 중에 있다. 이를 달성하기 위하여 정부는 화석연료를 대체하고 이산화탄소를 감축시키는 수단으로 바이오연료를 저탄소와 탄소중립자원으로 검토하고 있는 실정이다. 일반적으로, 목질계로부터 생산된 2세대 바이오연료는 수송부문에서 기존 화석연료를 대체하고 온실가스를 감축하는데 큰 효과가 있는 것으로 알려져 있다. 이러한 이유로 정부는 목질계 기반 바이오매스 액화연료(biomass-to-liquid fuel)에 대해 파일럿 수준으로 기술개발 중에 있다. 따라서 본 연구에서는 바이오매스액화연료 생산을 위한 동일공정으로 합성된 F-T(Fischer-Tropsch) 디젤의 연료적 특성을 연구하였다. 합성 F-T 디젤은 자동차용 경유에 단독 또는 혼합하여 사용할 수 있는 장점으로 인해 자동차용 경유엔진에 사용될 수 있다. 그 이유는 합성 F-T 디젤이 자동차용 경유와 비슷한 물리적 특성을 가지기 때문이다. 본 연구에 사용된 F-T 디젤은 Fischer-Tropsch (F-T) 공정을 이용하여 저온($240^{\circ}C$)에서 철 촉매를 가지고 합성되었다. 합성 F-T 디젤은 n-파라핀과 iso-파라핀을 함유하고, 등유와 경유 성분을 가진 $C_{12}{\sim}C_{23+}$ 분포로 이루어졌다. 합성 F-T 디젤은 합성 F-T 연료부터 증류를 통해 분리된 합성 F-T 디젤은 자동차용 경유에 비해 세탄가가 높으며, 방향족화합물은 매우 낮고, 황함량는 초저황(sulfur free) 수준으로 평가되었다. 또한 합성 F-T 디젤은 자동차용 경유와 비교하여 황과 방향족 화합물의 함량이 낮기 때문에 윤활성이 열악함을 보였다.

• Journal of Welding and Joining
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• 제34권3호
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• pp.6-11
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• 2016

Joining Al/Fe dissimilar metals is becoming a subject of special interest in the assembly of automotive parts as a trade-off between the weight lightening and the cost reduction. Although various studies have been introduced to join Al alloy with the steel sheet by fusion welding, weak joint strength and galvanic corrosion still remained as problems to be solved. As a solid state welding, friction stir welding has been preferred to fusion welding processes in the dissimilar metal joints. This study investigated friction stir spot welding (FSSW) of Al alloy to the thin steel sheet with a thickness of 0.65 mm. The conventional FSSW is a stationary spot welding process but new approach adopted an additional circumferential movement in company with high speed tool rotation. A full factorial experimental design was implemented, and the main and interaction effects of parameters were analysed on the failure load in the tensile shear test. The direction and radius of rotation were statistically significant parameters and these two parameters affected the joint width and the shape of the hook.

• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1944-1953
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• 2014

This paper shows the design and control methods of the bidirectional DC-DC converter to generate the proper DC-link voltage of a PMSM drive. Conventionally, because the controllable power of the PWM based voltage source inverter is limited by its DC-link voltage, the DC-DC converter is used for boosted DC-link voltage if the inverter source cannot generate enough operating voltage for the PMSM drive. In this paper, to obtain more utilization of this DC-DC converter, optimal DC-link voltage control for PMSM drive will be explained. First, the process and current path of the DC-DC converter will be illustrated, and a control method of this converter for variable DC-link voltage will then be explained. Finally, an improvement analysis of the optimal DC-link voltage control method, especially on the deadtime effect, will be explained. The DC-DC converter of the proposed control method is verified by the experiments by comparing with the conventional constant voltage control method.