• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.6
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• pp.33-38
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• 2012

EMB is considered as the next generation braking mechanism because it has simple structure and is environment friendly. However, as other brake mechanisms, EMB should be operated reliably for any operating conditions. EMB should be designed with fail-safe and fault-tolerant control concepts which require robust fault detection algorithms for various possible faults. In the design of fault detection algorithms, it is very difficult to construct faulty conditions in real EMB and thus, simulations are often used to emulate the faulty conditions. In this paper, a simulation tool is developed using the commercial software to emulate gear faults in the EMB mechanism. A backlash compensation algorithm is introduced based on contact point detection because screw backlash causes a delay in clamping force response time.

• Journal of Biosystems Engineering
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• v.32 no.3
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• pp.137-144
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• 2007

An anti-backlash gear was developed to reduce the rattle noise generated from the gearbox of a direct-engine PTO driveline of agricultural tractors under idling. A pair of gears using the anti-backlash gear as driven part was modeled and verified. Using the verified model, a computer simulation was conducted to investigate the effects of design parameters of the anti-backlash gear on the reduction of rattle noise. The optimum values of the design parameters were also determined by the computer simulation. The optimized anti-backlash gear was then manufactured and installed on the experimental PTO driveline for the performance test. Measurement of rattle noise was made to evaluate its performance before and after the driven gear of the PTO gearbox was replaced by the optimized anti-backlash gear. Results of the study were as follows: The optimum values of the design parameters, spring constant and deformation, may be determined by a relationship: $$k{\ge}\frac{4364.7}{150{\delta}-23.564}$$ The optimized anti-backlash gear reduced the rattle noise maximally by 16.9 dBA. This concluded that it would be most effective to use the optimized anti-backlash gear to eliminate the rattle noise in the PTO driveline.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.2
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• pp.12-19
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• 2010

The characteristics of the torsional systems are generally examined with the nonlinearities such as the several staged clutch damper springs, gear backlashes and drag torques. Generally speaking, the system's characteristics can be found out by the eigensolutions which can show the system natural frequencies and the mode shapes. However, these factors can not give the complete solutions to avoid the noise and vibration problems related to the nonlinear effects. Therefore, several assumptions should be made for solving the real physical system problems under the linear analysis which can reflect the nonlinear effects in the torsional system. This means that the several modified linear factors such as the modified clutch damper spring constants can be used to examine and avoid the natural frequency zones related to the noise and vibration problems. Under the linear analysis with the assumed and modified values, the system can be investigated with the more reliable ways for the realistic phenomena.

• Tribology and Lubricants
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• v.30 no.4
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• pp.212-217
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• 2014

A counter gear transmits the rotation angle, so the angular velocity ratio of the gear does not necessarily need to be constant in the meshing process. As a pinion has a small number of teeth when combined with an internal gear for counters, tooth interference can occur with the use of an involute curve. This paper introduces circular arcs that represent a tooth profile and fillet for the profile design of a pinion through the combination of arcs with lines. The straight line of a rack tooth represents the profile of a mating internal gear. Thus, the circular arc and line maintain contact during the rotation of the counter gear. This paper presents an analysis of the meshing of the circular arc tooth and rack tooth along with the properties of the counter gear, such as the change in rotational velocity and amount of backlash. The contact ratio of the counter gear is 1 because the tooth contact occurs between circular arcs and line. The initial position of tooth contact, which denotes the simultaneous contact of two teeth, is found. As the rotation of the pinion, only one tooth keeps the contact situation. This meshing property is analyzed by the geometrical constraints of the tooth profile in contact and the results are presented as graphical diagrams in which tooth-arc movements are superimposed.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.124-131
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• 2002

In this paper, an extended volumetric error model considering backlash in a three-axis machine tool was proposed and utilized for calculating the volumetric error of the machine tool at any position in three-dimensional workspace. Backlashes are interrelated; i.e. the angular backlash affects the straightness errors which then affect talc calculated squareness errors. Therefore, a new concept was introduced to define the backlash of squareness errors to incorporate the backlash of squareness error into the volumetric error, and the characteristics of the backlash of squareness error were investigated. The effects of backlash errors were assessed, by experiments. for 21 geometric errors of a machine tool. The backlash error was shown to be one of the systematic errors of a machine tool. And a generalized volumetric error model formulator for three-axis machine tools was developed, which allowed us to formulate machine tool synthesis error models far all possible machine tool configurations only with machine tool topology information. Based on these volumetric error model and model formulator, a computer-aided volumetric error analysis system was developed for a three-axis machine tool in this paper. Then the volumetric error at an arbitrary position can be obtained, and displayed in a three-dimensional graphic form.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.676-680
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• 2000

In this paper, an extended volumetric error model considering backlash in a three-axis machine tool was proposed and utilized for calculating the volumetric error of the machine tool at any position in three-dimensional workspace. Backlashes are interrelated; i.e. the angular backlash affects the straightness errors which then affect the calculated squareness errors. Therefore, a new concept was introduced to define the backlash of squareness errors to incorporate the backlash of squareness error into the volumetric error, and the characteristics of the backlash of squareness error were investigated. The effects of backlash errors were assessed, by experiments, fur 21 geometric errors of a machine tool. The backlash error was shown to be one of the systematic errors of a machine tool. Based on this volumetric error model, a computer-aided volumetric error analysis system was developed for a three-axis machine tool in this paper. Then the volumetric error at an arbitrary position can be obtained, and displayed in a three-dimensional graphic form.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.2
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• pp.165-170
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• 2012

This paper contains the test method to obtain aerodynamic hinge moments acting on the control surface of air vehicle wing. During the flight, hinge moments make difference between actual control surface angle and control angle which is measured by sensor of actuator. The hinge moments can be obtained by using this difference. Static ground load test and calibration test were conducted to obtain torsional stiffness of control surface actuation system. This results are used to calculate hinge moments. In addition, the mechanical errors of actuation system such as slip angle of mounting point and backlash could be estimated. Using flight test results, this experimental measurement method of hinge moment acting on control surface is conducted. The results of this method are similar to those of numerical simulation method, and the validity of this method is proved.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.19-19
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• 2017

자율주행 트랙터를 위한 트랙터 조향제어는 일반적으로 전자모터를 이용한 EPS(Electric Power Steering) 시스템을 스티어링 휠에 연결하여 회전변위를 변경하고 그 결과 오비트롤(Orbitrol) 밸브의 토출유량을 바꾸고 호스로 연결된 조향실린더의 변위를 조절하여 최종적으로 전방 타이어의 방향각을 변경하면서 이루어진다. 이러한 조향방식은 시스템 구조상 조향실린더와 오비트롤 밸브가 상대적으로 멀리 떨어져 있으며, 밸브 특성상 약 ${\pm}5^{\circ}$의 오버랩이 포함되어 있다. 또한, EPS의 전자모터는 관성력, 마찰, 백래시 등의 영향을 가진다. 이와 같은 복합적인 영향은 조향 응답을 느리게 만들어 상대적으로 빠른 속도에서 주행에서 추종성능이 떨어지는 문제가 발생한다. 본 연구에서는 자율주행 트랙터의 조향성능 개선 연구의 일환으로 조향 HILS 시뮬레이터를 설계제작하여 조향 성능의 요인을 실험적으로 구명하고자 하였으며 이를 바탕으로 조향 시스템의 설계개선 방안을 수립하고자 하였다. 시뮬레이터는 동양물산 80 마력급 TX803 트랙터에 사용되는 오픈센터방식의 오비트롤 유압회로 시스템을 기어펌프가 장착된 AC모터로 구동되게 구성하였으며, 유량은 모터의 주파수를 조절 회전속도를 조절 변경하였다. 추가적으로 EPS와 오비트롤 조합의 조향성능을 비교 및 개선하기 위해 비례제어밸브(PVG 32, Danfoss)를 추가 장착하였다. 실제 트랙터 조향 시 나타나는 마찰저항을 모사하기 위해 부하 실린더를 구성하였으며, 조향 실린더의 부하의 크기는 부하 실린더를 폐회로를 구성하고 유량비례제어밸브를 이용한 유로의 개구량 조절을 통해 부하의 크기를 약 4000 N 까지 증가시킬 수 있도록 하였다. EPS와 비례제어밸브를 제어하기 위해 CANoe 8.0 소프트웨어를 이용하여 CAN통신 기반 가상 조향ECU를 구성하였으며 오비트롤의 기본 성능을 확인하기 위해 조향휠에 따른 실린더 동특성 및 계단 추종성능을 비례제어밸브와 비교하였다. 오비트롤 밸브는 약 ${\pm}5^{\circ}$이상 동작 시 실린더 압력이 상승하기 시작하였으며, 이후 약 ${\pm}10^{\circ}$이상 동작 시 조향실린더가 동작하기 시작하였다. 계단 추종성능실험에서는 비례제어밸브가 약 2배 이상의 응답개선을 나타냈다. 자율주행 경로추종 성능을 향상시키기 위해서는 순간적인 출력밀도가 높은 비례제어밸브를 통해 응답개선이 필요한 것으로 나타났다.

• Journal of Popular Narrative
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• v.27 no.1
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• pp.133-185
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• 2021

This study is an attempt to connect television drama M, which deals with abortion issues, with theoretical focus such as materiality, relativity, and agency, to understand diffractively as an cartography of agential reality. According to Karen Barard's Agential Realism, Television drama M is a sociocultural phenomenon produced by the agential intra-actions of material-discursive apparatuses such as medical technology, ghost stories and legends, and male-affect. The 1990s repeatedly revealed "hate" through apparatuses such as technology, discourse, and affect, which are directed at women's gendered bodies. The material -discursive practice of plastic surgery and abortion proves that the agential reality surrounding the body is closely intertwined with medical technology, as well as with the genderized hate. Another related material-discursive phenomenon is rediscovery of the legend and fad of the ghost story, which is also produced from the hate of the denaturalized body, which is once again expanded and reproduced. Appearing in this environment of affect, M enacts diffraction, which is based on backlash, lacking posthuman implications for the materialization of the techno-body. M puts humanistic assumptions about "Man" as a universal definition, historically framed and defined in context. But it is not universal and it is gendered. The current time when the political turmoil surrounding medical technology, discourse, and bodily matters is violently intra-acted is the time to carefully account and respond to the alternative definitions of human beings that M has rejected.