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디스크 브레이크 로터 마찰면 가공 형태에 따른 성능 변화 연구
정택수(Taeksu Jung),차바우(Bawoo Cha),홍윤화(Yunhwa Hong),김청민(Cheongmin Kim),홍영훈(Younghoon Hong),조종두(Chongdu Cho) 한국자동차공학회 2016 한국 자동차공학회논문집 Vol.24 No.4
Cross-drilling and slotting on the frictional surface of a brake rotor are methods used for improving the performance of the brake system. These shapes have particular advantages, such as the shaving effect of a slotted shape, which maintains a clean pad-to-rotor contact surface, and the venting effect of a drilled shape, which provides passageways for the gas to escape. In order to understand the effect of the machined pattern on the brake performance aspect, an experimental method is adopted along with the dynamometer test. The cross-drilled rotor, slotted rotor, and mixed pattern rotor with cross-drilling and slotting machining are prepared and tested in terms of friction coefficient, temperature, braking torque, and noise.
정택수(Taeksu Jung),조종두(Chongdu Cho) 한국자동차공학회 2014 한국 자동차공학회논문집 Vol.22 No.7
Automotive NVH on brake operation is mainly caused by a coupling action of vehicle speed and inter parts friction and its frequency occurs over a broad band of 0.1 kHz~10 kHz. Especially, squeal noise, being a self-excited vibration generated by friction force between drum and lining, occurs over 1 kHz and consequently dynamic instability is induced when friction energy is applied to a brake vibration system. The squeal strongly depends on nonlinear properties influenced by the material of lining, velocity of vehicle, and the dynamic properties of a brake system. The dynamic properties are considered as a main influential design factor to squeal noise, however the analysis of the properties are rarely facilitated due to arbitrariness of shape by wearing down. In this paper, we research generating tendency of squeal noise through complex eigenvalue analysis, tracking drum brake’s unstable modes in accordance with the wear shape of drum and lining such as tapered and bellmouth shape, and analyze computed unstable modes by variable shapes.
타이밍 체인 시스템의 초기 장력이 전달 오차에 미치는 영향
박용식(Yongsik Park),정택수(Taeksu Jung),홍윤화(Yunhwa Hong),김영진(Youngjin Kim),박영균(Youngkyun Park),이정진(Jungjin Lee),조종두(Chongdu Cho) 한국자동차공학회 2017 한국 자동차공학회논문집 Vol.25 No.2
The timing chain system, which is a typical power transmission technology applied to a vehicle, has been widely used by the automotive industry because it is normally designed to last a car’s lifetime. However, the timing chain system may cause some problems due to the shape of the chains and the polygonal behavior on contact between the chain and the sprocket. In addition, noise and vibration caused by transmission error are the most typical problems encountered by major automotive manufacturers and they are considered as the main source of customer complaint. The initial tension of the chain-sprocket system is thought to be the main cause of transmission error, and it is regarded as the source of engine vibration and noise. The initial tension of the chain system should be controlled carefully since a low initial tension can cause twisting, which may lead to a system malfunction, while a high initial tension can reduce the service life due to a worn down contact surface. In this paper, the kinematic analysis model is generated with various initial tensions, which are controlled by changing the shape of the fixed guide with the largest contact surface with chain. The results showed that the transmission error was minimized on a particular range of initial tension, and the tendency showed that the error changed with a higher sensitivity at a lower initial tension.
이종화(Jonghwa Lee),정택수(Taeksu Jung),조종두(Chongdu Cho),김주용(Jooyong Kim) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.11
District heating system on an apartment block recently attracts attention to combine hot water supply pipes which are separated with space heating pipe and warm water supply pipe in current system, and this new system is applied for a part of European nations. In combined system, only one heat source is supplied to the house and distributed for space heating and warm water generating by household substation. Therefore, the effective distribution of supplied heat source in accordance with purposes becomes more important. This paper presents a new three-way proportional control valve for mentioned combined heat source system in district heating with experimental result. The valve operates for controls to divides heat source into two different directions : hot water distributor for space heating and household substation for warm water supply in accordance with the pressure drops of tap water induced by the user. This study shows the controllability and performance of the mechanical control three-way proportional valve for common pipe district heating system with result of experiment.
이종화(Jonghwa Lee),정택수(Taeksu Jung),조종두(Chongdu Cho),김주용(Jooyong Kim) 대한설비공학회 2014 설비공학 논문집 Vol.26 No.5
Korea District heating corp. recently give an attention to combine the district heating and supply pipes as a two pipe system that are in the present system separated with room heating and warm water supply pipe, and the two pipe system is commonly applied for heating service in European countries. In the new two pipe system, only one heat source is supplied to a house and partitioned into room heating and warm water supply by household substation. So the effective distribution of supplied heat source in accordance to user intention is very important. This paper presents the development and performance test of three-way proportional control valve for a combined heat source system in district heating. The proposed valve is controlled to partition heat source into two different directions:hot water distributor for space heating and household substation for warm water supply in response to the pressure drops of tap water caused by the user. The performance investigation is shown within 3% of error compared to the theoretical model of the three-way proportional valve and its controllability is verified.