• 동력기계공학회지
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• 제11권2호
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• pp.58-63
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• 2007

Vehicular safety and occupant injury have been of considerable interest to the public. The dynamic response of an articulated vehicle is different from that of single body vehicle due to its geometric and inertia properties. Articulated vehicles have the tendency to jackknife if they lose driving safety. Influence of factors for driving safety of an articulated vehicle(Tractor-Semitrailers) has been analysed by the EDVTS, a kinetic analysis program for an articulated vehicle. EDVTS permits an analyst to investigate the effect of many variables in a short period of time, and enables to obtain an accurate explanation of driving safety. The factors used in the analysis include the load, friction coefficient, tire flat, increase of braking force, and trailer geometry. Based on the results, the articulation angle and driving safety were influenced remarkably by the load, coefficient of friction, increase of braking force. However, trailer geometry, such as length and width, did not affect articulation angle and driving safety

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.324-324
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• 2008

Piezoelectric ceramics is an active element that makes stator to vibrate to generate rotational force in ultrasonic motors. In drive of ultrasonic motors, many factors that affect to the resonance characteristics of piezoelectric ceramics exist. For example, those factors are bonding condition with elastic body, the magnitude of electric field, the normal force for frictional drive and the emission of heat due to vibration and friction and so on. Therefore, it is important to research the inclination of property variation of piezoelectric ceramics in circumstance that has complex elements. In this paper, we focused and analyzed the resonance characteristics of ultrasonic motor due to the magnitude of the driving voltage and normal force.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.238-240
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• 1997

In two case, LPM driving by full step or microstep, we simulated the thrust force in LPM using finite element method and measured the force by experimental equipment. And We analyze the harmonics of trust force by Fast Fourier Transform. We proposed the method, which can reduced harmonic force by microstep driving.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.166-173
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• 2002

The wheel bearing hub unit is developed type of wheel bearing unified with the hub parts. It has advantage of reducing the weight and the number of components. And, it also improves uniformity of manufacturing quality, In order to design the wheel bearing hub units, many techniques are used such as load analysis, structure analysis and bearing characteristics analysis and so forth. These techniques need highly accurate load conditions founded on service conditions. In this study, to design the wheel bearing hub units used widespread in passenger cars, the service load was measured through driving tests on the public roads and in the special events. The public roads are classified into highway, intercity road, rural road, urban road, and unpaved road so as to know what the characteristics of the road loads are. The results of the tests showed that the wheel force was relative to the lateral acceleration, and also could be calculated from the lateral acceleration. The lateral acceleration was measured from 0.0G to 0.6G in general driving on the public roads, with different distributions in each road type. In special events, the maximum lateral acceleration was measured from 0.8G to 1.3G.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.847-852
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• 2007

This paper investigates the characteristics of cogging torque and magnetic force of a brushless DC (BLDC) motor due to imperfect magnetization of permanent magnet (PM) numerically and experimentally which results in the magnetically induced vibration. A predicted magnetization pattern of the PM of the BLDC motor, which is derived from the measured surface magnetic flux density along the PM, is applied to the finite element analysis in order to calculate the cogging torque and the unbalanced magnetic force. This research also develops the experimental setup to measure the unbalanced magnetic force as well as the cogging torque. It shows numerically and experimentally that the imperfect magnetization of permanent magnet generates the driving frequencies of cogging torque with integer multiple of slot number in addition to the least common multiple of pole and slot. It also shows that the driving frequencies of unbalanced magnetic force are integer multiple of slot number ${\pm}1$ due to imperfect magnetization of PM even in the rotationally symmetric design.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.952-957
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• 2015

Recently, the interior permanent magnet (IPM) motors for electric vehicle (EV) traction motor are being extensively researched because of its high energy density and high efficiency. The traction motor for EV requires high power and high efficiency at the wide driving region. Therefore, it is essential to fully consider the characteristics of the motor from low speed to high-speed driving regions. Especially, when the motor is driven at high speed, a significant centrifugal force is applied to the rotor. Thus, the rotor must be stably structured and be fully endured at the critical speed. In this paper, aims to examine the characteristics of the IPM motor by adjusting the width of air-barrier according to the permanent magnet position which is critical in designing an IPM motor for EV traction motors and to conduct a centrifugal force analysis for grasping mechanical safety.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.539-544
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• 2004

This paper discusses the measurement of tire driving performance for 2 types of tire model. Tire is almost composed of rubber, and this is related with the bearing capacity of tire due to the external force. In this study, an explicit time integration method has been used to simulate steady state rolling along a straight path and over a cleat. And analysis for tire dynamic response rolling over a cleat is importnat to study automobile NVH properties. Besides, the evaluation of contact shear force is perfomed for steady state rolling and braking state. The results show that there are noticeable differences between 205/60R15 and 225/60R15 tire model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.745-749
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• 2002

This paper is on the study of flow force compensating method of spool type valve. A simple flow force compensating method using stepped spool is presented in this paper. It is easy to manufacture stepped spool in the presented method because the shape of it is simple. The method has the merit that the size of valve need not be increased. Actuating force required for driving means of spool can be decreased by the compensation of flow force. The effect of presented method is predicted through CFD analysis. The prototypes of flow force compensating Direct Drive Servo-Valve where the result of CFD analysis is reflected are manufactured, and the measurement of flow force is carried out. It is known from the measurement that the effect of flow force compensation is very similar to from CFD analysis.

• 한국정밀공학회지
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• 제20권6호
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• pp.145-150
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• 2003

This paper is on the study of flow force compensation for spool type valves. A simple method for flow force compensation using a stepped spool is presented in this paper. It is easy to manufacture the stepped spool of the presented method because the shape of it is simple. The method has another merit that the size of valve need not be increased. Actuating force required for driving the spool can be decreased through the compensation of flow force. The effect of presented method is predicted through CFD analysis. The results of the CFD analysis are also utilized for the optimization of step shape. The prototypes of flow force compensated Direct Drive Servo-Valve are manufactured, and the measurements of flow force are carried out. The measured effect of flow force compensation is very similar to that from the CFD analysis.

• 대한기계학회논문집
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• 제19권2호
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• pp.451-462
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• 1995

Single overload tests performed to examine the crack retardation behavior for the specimen thickness and overload ratios. Delayed crack length was tend to increase in small thickness and big overload ratio but was difference between delayed crack length and plastic zone size that expected in specimen thickness. So retardation behavior that estimated in plastic zone size, was not sufficient. Crack tip branching and striation distribution, secondary mechanisms that effected in retardation behavior, was examined by experiment and finite element analysis. Crack tip branching was affected by micro structure, and appeared the more complicatedly according to increasing damage by overload and decreasing crack driving force in base line stress level. And crack tip branching the branching angle decreased crack driving force in the crack tip. And a characteristic of the fractography on retardation zone was that striation distribution did not appear due to decreased crack driving force.