• 한국자동차공학회논문집
• /
• 제18권6호
• /
• pp.138-144
• /
• 2010

If the vibration is occurred in a large-sized bus roof, it makes people annoying and complaining the quality of a large-sized bus. So in design stage, it must be considered. To assess vibration at the roof which is equipped with air conditioner in design stage, finite element model is constructed. Computer simulation analysis and experimental method are performed. The dynamic characteristics of the large-sized bus are found by using eigenvalue method. It is related with dynamic behavior. The running conditions of a large-sized bus are velocity and road condition which followed experimental conditions. And the frequency response of a large-sized bus is well correlated with analysis result. Modal participation method is used for finding major modes at each peak. Using this method, we found that front and rear suspension system, engine mounting system and roof structure are the major reasons of the roof vibration. To reduce vibration level of roof in a large-sized bus, spring stiffness of front and rear suspension system, spring stiffness of engine mounting system and roof structure are properly combined. From this study, the vibration characteristics of the roof structure of a large-sized bus can be to a satisfactory level.

• 한국자동차공학회논문집
• /
• 제5권6호
• /
• pp.148-154
• /
• 1997

The safety problems of buses have been arisen due to the increasing of road traffic. Occupant injuries are always possible in the rollover accident and the frontal impact. Thus the structure of bus should have sufficient strength to protect passengers under accidental loads. ECE(Economic Commission for Europe) regulation No.66 prescribes that the superstructure of the vehicle shall be sufficient strength for passengers' surviving and the residual space shall be preserved in the passenger compartment during and after the standard rollover accident situation. Rollover test and simulation on a large-sized bus was completed according to the regulation. The coordinates of the points on the bus were measured by photogrammetry system. The rollover situation was revived by structural crashes simulation software, PAM-CRASH, and it was checked that the structure still complied with the requirements of residual space during rollover situation. The residual space was preserved during rollover, so it was proved that the structure of the investigated bus had much probability of survival in rollover accidents.

• 대한전기학회논문지
• /
• 제32권12호
• /
• pp.435-440
• /
• 1983

The methods of forming the bus impedance matrix, which is mainly employed in fault analysis of power system, can be generally classified in catagories, (1) the one being the inverse matrix of bus admittance matrix, and (2) the other the bus impedance matrix succesive formation method by particular algorithms. The former method is theouetically elegant, but the formation and inverse of complex bus admittance matrix for large power system requires too much amounts of computer memory space and computing time. The latter method also requires too much memory space. Therefore, in this paper, an algorithm and computer program is introduced for the formation of a sparse bus impedance matrix which generates only the matching terms of the admittance matrix. So, this method can reduce the computer memory and computing time, and can be applied to fault analysis of large power system by small digital computer.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제50권10호
• /
• pp.509-516
• /
• 2001

Isolated phase bus(IPS) has a special structure for carrying large current generated by a generator to a main transformer. In the analysis of IPB, the understanding of the magnetic field distribution generated by large current is important. Especially, while the bus conductor current is flowing, almost same amount of current as bus conductor current is induced in the enclosures under the influence of time varying magnetic field, and therefore the large electric loss and the deterioration of insulating capability might occur due to Joule heating effect. Hence for the optimal design of IPB satisfying the condition to minimize the loss, the accurate analysis of magnetic field distribution and the eddy current characteristics of three phase isolated phase bus have been investigated. In the analysis of time varying magnetic field, instead of finite difference method(FDM) which is generally used, finite element method with phasor concept is investigated under the assumption that the bus current is purely sinusoidal. The characteristics is studied along the phase angle by comparing the effect of eddy current on the magnetic field distribution with the case that eddy current is not considered, and also the effect of material, thickness and radius of enclosure on the eddy current distribution is discussed.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
• /
• pp.189-192
• /
• 2001

Resin transfer molding process has been widely used in the automobile industry, because the product with large area can be manufactured easily and the cost for the manufacturing is lower than that of compression molding and hand lay up method. Since RTM process is suitable for large bus housing panels, in this work, the composite housing panel was manufactured by RTM process and the mechanical properties, surface quality and the condition of manufacturing process were studied.

• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2000년도 춘계학술대회
• /
• pp.97-110
• /
• 2000

Production schedule and realization quantity of Large type bus [929(HD), 928, 928-A(SD), 937E/L, 937/L,] were analyzed in order to intruoduce FMS(Flexible Manufacturing System) appropriate for varities of customer desire and multi-item, small lot production. And this paper is aimed to propose introduction method of FMS, analyzing zig tools change times and idle times with production line and workers as an object. According to analysis results, only simple spec., depending on bus type, changed with decrease in production. For 929(HD), 928,928-A(SD), 937Eh, 937/L bus type, there was no harmony between schdule and realization. Therefore, it caused many difficulties in part supply. And there was loss of manpower and reduction of productibility due to idle time of process with bus type change. Production processes were operated inefficiently because tact time exceeded or shortaged of allow time.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1990-1992
• /
• 2000

Isolated phase bus is, as a special bus which allows large current from a generator to main transformer, composed of main conductor, enclosure and auxiliary equipments such as insulating bellows, bus elbows, support insulator, etc. To develop this kind of high power devices, it is required to secure the technique of selection of conducting and insulating materials, basic arrangement skills, and analysis on eddy current which causes temperature increase in enclosures. By the way, these techniques are based on the analysis of electromagnetic phenomena for high voltage and large current. In this study, an electromagnetic field analysis program is developed and applied to the isolated phase bus. which could be the basic numerical method for the analysis design and modifying isolated phase bus.

• 전기의세계
• /
• 제23권1호
• /
• pp.61-68
• /
• 1974

This paper attempts to develop the algorithms and computer program for load flow solution and faults analysis of large power system by small digital computer. The Conventional methods for load flow solution and fault analysis of large power system require too much amount of computer memory space and computing time. Therefore, this paper describes the methad for reducing the computer memory space and computing time as follows. (1) Load Flow Solution; This method is to store each primitive impedance of lines along with a list of bus numbers corresponding to the both terminals of lines, and to store only nonzero element of bus admittance matrix. (2) Faults Analysis: This method is to partition a large power system into several groups of subsystems, form individual bus impedance matrix, store them in the storage, and assemble the only required portion of them to original total system by algorithm.

• 대한교통학회지
• /
• 제24권5호
• /
• pp.123-133
• /
• 2006

서울시를 포함한 수도권 각 도시는 중앙버스전용차로의 적극적인 도입으로 버스속도 및 정시성 향상을 통해 대중교통우선 처리 전략을 적극 추진 중에 있다. 그러나 이로 인해 중앙부 $1{\sim}2$개 차로를 버스전용차로가 차지함으로써 기존 신호운영체계에 큰 변화를 가져오게 되었다 좌회전 차량과 중앙버스전용차로를 이용해 직진하는 버스간에 새로운 상충이 발생하게 되어 동시신호 기법 등 교차로 신호운영대안이 줄어들게 된 것이다 이 해결방안으로서 버스전용신호를 도입하여 중첩현시 및 동시신호 등 Dual-Ring방식의 다양한 신호 운영을 가능케 하는 방안이 모색되고 있다. 본 연구에서는 이러한 버스전용신호 도입 시 교차로 정체를 최소화할 수 있는 신호설계방법을 제시하였고, 중앙버스전용차로가 운영 중인 양재역사거리에 동 기법을 이용한 최적신호 설계를 적용, 시뮬레이션을 통해 그 효과를 검증하였다.

• 한국자동차공학회논문집
• /
• 제9권4호
• /
• pp.176-183
• /
• 2001

It is difficult to find out the kinematic characteristics of a vehicle suspension without the usage of CAE software. The application of CAE software into suspension kinematics and dynamics yields the more precise knowledge on the chassis design. In this study, the influence of the suspension geometry on the handling performances of a large-sized bus is investigated using the DADS software. The front and rear suspension of a large-sized bus are a rigid axle suspension with the four control links. The elastokinematic analysis is performed to evaluate the roll characteristics of the front and rear suspension. The elastokinematic responses are evaluated in terms of the roll center height and roll steer for various geometric parameters. The roll center height is mainly dependent on the vertical displacement of a panhard rod and the vertical displacements of lower control links affect the roll steer of a rear suspension. The parameter study with the change of rear suspension geometry is conducted to investigate the vehicle handling performances. This parameter study shows that the vertical displacement and orientation of a panhard rod influence the handling performances of a large-sized bus significantly.