• 전기학회논문지
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• 제60권10호
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• pp.1903-1914
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• 2011

In this paper, we propose vehicle running characteristic simulator. The developed simulator is configured by two induction motors which are directly coupled with each other. One motor is to simulate the vehicle drive and another motor is to simulate the vehicle dynamic load including running resistance, gradient resistance and adhesive characteristics between rail and wheel. The running characteristics of vehicle are modeled by numerical formulas. These are programed by software of embedded controller. Thus, it is possible to change several running characteristics during the running test freely and instantly. To evaluate the feasibility of the simulator, the experiments on slip and adhesion coefficient are performed. Additionally the adhesion control and speed control of vehicle are tested with simulator. Experimental results show that the simulator can produce the driving characteristics similar to the vehicle system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권1호
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• pp.32-39
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• 2000

In this paper, an improved re-adhesion control scheme is proposed for 1C4M railway traction system. It is well known that the coefficient of adhesion between wheel and rail has a maximum value at a certain slip velocity. In the proposed scheme, adhesive effort is estimated by a full-order observer and the driving torque of motor is controlled to get maximum adhesive effort. The-adhesion control simulator is designed to verify the proposed re-adhesion control algorithm. The simulation results and experimental results are presented.

• 한국표면공학회지
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• 제56권5호
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• pp.328-334
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• 2023

The carbon-based films have various properties, which have been widely applied in industrial application. However, it has critical drawback for poor adhesion between films and metal substrate. In the present work, we have deposited carbon-based films on injection mold steel by plasma assisted chemical vapor deposition (PACVD). In order to improve adhesion, prior to film deposition, the substrate was nitriding-treated using PACVD. And its effect on the adhesion was investigated. Due to the pre-nitriding, the amorphous carbon nitride (a-CN:H) films presented 10 times higher adhesion (34.9 N) than that of un-nitirided. In addition, a friction coefficient was decreased from 0.29 to 0.15 for the amorphous carbon (a-C:H) due to improved adhesion. The obtained results demonstrated that pre-nitriding considerably improved the adhesion, and the relationship among adhesion, hardness, and surface roughness was discussed in detail.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2649-2651
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• 2005

In trains driven by electric motor, when the adhesion force between rail and driving wheel decreases suddenly, the electric motor coach has slip phenomena. The characteristics of adhesion force coefficient are strongly affected by the conditions between rails and driving wheels, such as moisture, dust, and oil on the rails and so on. This paper proposes the vector control structure for the improved re-adhesion control with paralleled control of induction motors under the sudden variation of the adhesion force.

• 농약과학회지
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• 제19권3호
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• pp.317-322
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• 2015

본 연구는 농약 살포량과 유효성분의 부착량 그리고 해충방제 효과와의 상관관계를 조사하여 효율적 해충방제를 위한 적정 농약 살포량을 도출하는 기초 자료를 얻고자 실시되었다. 시험약제의 유효성분인 acetamiprid의 표준검량선의 직선성 $R^2=0.9994$, 회수율 71~93%, 변이계수 6% 이하로 농약 잔류분석기준에 적합하였다. 2015년도 실험에서는 살포량을 전년도보다 70 L 감량한 302 L/10a로하고 살포압을 낮추어 살포한 후 유효성분의 부착량을 비교 분석한 결과, 부착량의 상관계수가 82%에서 69%로 낮게 조사되어 전년도에 비해 고르게 살포되었음 알 수 있었다. 약제 살포량을 줄였음에도 해충에 대한 방제가가 95%이상 우수한 것으로 나타나, 유효성분 부착량의 상관계수와 밀접한 관계가 있는 것으로 보여 진다. 또한 사과원 토양 표면의 유효성분 부착량을 분석한 결과 과수에 부착되는 양과 비교해 2.2배까지 높게 부착되는 것으로 분석되었다.

• 한국표면공학회지
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• 제28권6호
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• pp.343-351
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• 1995

Titanium nitride films have been prepared on various substrates (silicon wafer, HSS) by cathode arc ion plating process to measure microhardness, adhesion and wear-resistant behaviors by changing the substrate bias voltages (0∼-300V), thickness and roughness. Microhardnesses were measured by micro vickers hardness tester, the adhesion strengths were evaluated by acoustic signals through the scratch test with incremental applied load. As the substrate bias voltages were increased, the ｛111｝ orientation was predominant, the microhardnesses and adhesion strengths of tool steel were observed to be stronger than those of without subatrate bias voltage. Adhesion strengths of the substrate bias were 4-7 times higher than those of without the substrate bias, confirmed by SEM with EDX. Wear resistances were used pin-on-disk tribotester and TiN costing reduced the abrasive wear. As the substrate bias was increased, the weight loss and the friction coefficient was decreased.

• 제어로봇시스템학회논문지
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• 제11권6호
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• pp.502-509
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• 2005

In this paper, a 4-wheel vehicle model including the effects of tire slip was considered, along with variable parameter sliding control, in order to improve the performance of the vehicle longitudinal response. The variable sliding parameter is made to be proportional to the square root of the pressure derivative at the wheel, in order to compensate for large pressure changes in the brake cylinder. A typical tire force-relative slip curve for dry road conditions was used to generate an analytical tire force-relative slip function, and an antilock sliding control process based on the analytical tire force-relative slip function was used. A retrofitted brake system, with the pushrod force as the end control parameter, was employed, and an average decay function was used to suppress the simulation oscillations. The simulation results indicate that the velocity and spacing errors were slightly larger than those obtained when the wheel slip effect was not considered, that the spacing errors of the lead and follower were insensitive to the adhesion coefficient up to the critical wheel slip value, and that the limit for the antilock control under non-constant adhesion road conditions was determined by the minimum value of the equivalent adhesion coefficient.

• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1801-1812
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• 2006

In this paper, a 4-wheel vehicle model including the effects of tire slip was considered, along with variable parameter sliding control, pushrod force as the end control parameter, and an antilock sliding control, in order to improve the performance of the vehicle longitudinal response. The variable sliding parameter is made to be proportional to the square root of the pressure derivative at the wheel, in order to compensate for large pressure changes in the brake cylinder. A typical tire force-relative slip curve for dry road conditions was used to generate an analytical tire force-relative slip function, and an antilock sliding control process based on the analytical tire force-relative slip function was used. A retrofitted brake system, with the pushrod force as the end control parameter, was employed, and an average decay function was used to suppress the simulation oscillations. Simulation results indicate that the velocity and spacing errors were slightly larger than the results that without considering wheel slip effect, the spacing errors of the lead and follower were insensitive to the adhesion coefficient up to the critical wheel slip value, and the limit for the antilock control on non-constant adhesion road condition was determined by the minimum of the equivalent adhesion coefficient.

• 열처리공학회지
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• 제20권2호
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• pp.78-83
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• 2007

CrN coatings were deposited by cathodic arc ion plating method on the SKD11 steel substrates. Atmosphere temperature of $350^{\circ}C$, arc current of 90 A, nitrogen partial pressure of 1.0-5.3 Pa, and negative bias voltage of 30-135 V were selected. The characteristics of microstructure were investigated with XRD. Hardness, adhesion and friction coefficient measured by microhardness tester, scratch tester, and ball on disk tribometer. Microstructures depended on nitrogen partial pressure and bias voltage. The preferred orientation of the films was changed from (200) to (111) with decreasing pressure and increasing bias voltage. Adhesion properties related with microstructure, but microstructure changes slightly influenced on hardness and friction properties. The critical load.($Lc_1$) and hardness of CrN films deposited at 5.3 Pa, -30 V condition were 55 N(HF1), $2157{\pm}47\;Hk_{0.025}$. The friction coefficient were about 0.5 under dry condition.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.383-386
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• 2005

An integrated analytical model which should have essential dynamics on the longitudinal railway vehicle is developed. The model consists of translational movement, rotational movement, brake actuator, adhesion force between rail and wheel, and brake friction force between wheel and pad. Thus, during the deceleration for stopping, a feedback controller controlling the brake cylinder pressure is designed to improve ride quality and to release friction problems. Through the developed model, the feasibility of controlling the cylinder pressure is verified for the better performances during braking.