• Journal of the Korean Society for Precision Engineering
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• v.1 no.2
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• pp.47-57
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• 1984

The porous matterials are used both to control the flow of the compressed gas and to serve as the bearing surface. This porous design offers several advantages over the conventional externally pressurized gas bearings. It can simplify the construction, lower the gas consumption, and make the cleaning of the gas supply less critical. Test apparatus was cinstructed to experi- mentally investigate maximum load capacity of thrust bearing was measured 200 Kg (15Kg/$\mu$m), and radial bearing was 36 Kg/$\mu$m. And a rotation accuracy of face waving was 0.0127$\mu$m, and center waving was measured 0.5 $\mu$m. Finally, the use of this method of design and manufacturing will contribute to many practical application in the field required for precision and high stability.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.116-118
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• 2003

The Slotless Permanet-magnet linear synchronous motors (PMLSM) have been developed for factory automation, transportation applications, wafer steppers, conveyance system, and so on[1]. The current analysis and design are treated in air-cored PMLSM. The main purpose of this paper is to provide a general design and analysis framework for the iron-cored linear permanent-magnet machines. Based on field solution using two dimensional analytical technique the magnetic field required magnet volume size, optimal winding thickness size, winding flux linkage and thrust will be discussed.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.973.1_974.1
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• 2009

One of the most important technical improvement required for ropeless elevator system to become practical is the improvements in overall system efficiency. Moreover, the predominant drawback of permanent magnet (PM) linear synchronous motor (LSM) is large detent force. Therefore, for the given volume the selection of high power density PM-LSM with low detent force is very imperative. In this paper, we will investigate the characteristics of thrust and detent force of PM-LSM under different motor topology structure. Finally, the long stator double-sided iron core type PM-LSM with fractional slot winding is the best choice for the ropeless elevator system.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.94-104
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• 1994

In order to improve engine performance and its reliability it is very important to find the friction force between piston-ring assembly and cylinder wall in engine operating conditions. A new system was developed for the piston-ring assembly friction force measurement. This system had a relatively high fundamental frequency at 884 Hz and a fine resolution of 0.5N in friction force measurement. Comparing with existing floating liner systems this systems required small installation space and at the same time alleviated the system noise problem induced by the thrust and slap impulse forces.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.426-430
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• 2005

The COMS(Communication, Ocean and Meteorological Satellite) is the first developed three-axis stabilization multi-function satellite on geostationary earth orbit(GEO) in korea, presently scheduled to be launched in 2008. The COMS propulsion system provides the thrust and torque required for the insertion into GEO, attitude and orbit control/adjustment of spacecraft. In this paper, system design of propulsion system, basic functions and design requirement of components are described.

• Journal of Astronomy and Space Sciences
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• v.25 no.3
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• pp.255-266
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• 2008

The current paper presents application of a new analytic solution in general relative motion to spacecraft formation flying in an elliptic orbit. The calculus of variations is used to analytically find optimal trajectories and controls for the given problem. The inverse of the fundamental matrix associated with the dynamic equations is not required for the solution in the current study. It is verified that the optimal thrust vector is a function of the fundamental matrix of the given state equations. The cost function and the state vector during the reconfiguration can be analytically obtained as well. The results predict the form of optimal solutions in advance without having to solve the problem. Numerical simulation shows the brevity and the accuracy of the general analytic solutions developed in the current paper.

• Tribology and Lubricants
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• v.26 no.6
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• pp.322-328
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• 2010

An inter-propellant seal (IPS) for 75 ton class thrust turbopump was tested. Leakage characteristics were presented with a given range of pressure difference under cryogenic as well as room temperature conditions. For cryogenic tests, liquid nitrogen was used as analogic fluid of liquid oxygen (LOX) while water was used instead of kerosene for room temperature condition. Test results showed that IPS had satisfactory leakage performance. Additionally endurance test was conducted to prove the life time of manufactured IPS and the tested IPS had successfully survived during required life time, 2100 seconds.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.9
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• pp.459-464
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• 2006

The detent force by end-effect has an undesired influence on moving coil type Permanent Magnet Linear Synchronous Motor(PMLSM). So, the reduction of detent force by end-effect is especially required for the improvement of thrust characteristics. In this paper, in order to reduce detent force by end-effect, the auxiliary-teeth is installed at the end part of mover. It is also analyzed by Finite Element Analysis(FEA) and optimized by using neural network. By comparison, the detent force is reduced about 41.4[%] comparing to that of basic model.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.389-394
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• 1991

The surface-to-air missile system using Command to Line-Of-Sight (CLOS) guidance law is represented by complex nonlinear differential equations with 6 degree-of-freedom. This paper presents the characterictics of missile system and the effect of various error sources by Monte-Carlo simulation method. By simulation the part of playing a main role in the surface-to-air missile system is radar. Therefore for the performance of missile system the development of the technique reducing the error of radar is required. And the effect of accelerometer error is a few large, too. But, because accelerometer costs cheap this problem is solved easily. And the main error source of missile system data is the thrust, which affects directly to acceleration. The result is the important information about designing and fabricating missile system. And this makes the missile system best because of sharing elaborate and expense effectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.820-823
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• 2003

Recently, the linear motors have been widely used in the industry, owing to various advantages in comparison with conventional feed mechanism; high speed, high acceleration and high stiffness. In addition, the linear motors have the merits of a good velocity control, reversible movement and long lifetime. For the application of the linear motors to vibrating conveyor, the study of vibrating characteristics is required. In this paper, we developed the linear vibrating conveyor using the linear motor that has the 410N thrust and the 7.2m/min maximum moving velocity. To accomplish this system, we had some experiments that included the influence of deceleration time, vibrating amplitude and additional weight.