• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1179-1184
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• 2007

An unmaned surveillance robot consists of rifle, laser receiver, thermal imager, color CCD camera, and laser illuminator. A human guard can be replaced with such a robot to take care dangerous surveillance tasks. Currently most of surveillance robots are mounded at a fixed post to take care of surveillance tasks. In order to watch blind areas, it is necessary to modify such a surveillance robot to become a mobile robot. In this paper, simulation based design procedure of mobile surveillance robot has been introduced. 3D CAD geometry model has been produced using Pro-Engineer. Required pen and tilt motor capacities have been analyzed using ADAMS inverse dynamics analysis. A target tracking and stabilization control algorithm of the mobile surveillance robot has been developed in order to stabilize the system from the motion of the vehicle which experiences the rough terrain. ADAMS-Matlab co-simulation has been also carried out to validate the proposed target tracking and stabilization algorithm.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.697-704
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• 2007

Recently, a variable valve timing system has been widely adopted in internal combustion engine in order to improve the fuel economy and torque at low engine speed. In addition, it is known that varying valve timing according to the various engine operations could reduce exhaust gas, especially NOx, because of residual gas by valve overlap. In this study, to improve the low exhaust gas and fuel economy at part load condition, the residual gas and back flow of exhaust gas due to valve overlap were calculated computationally. Moreover, the characteristics of engine performances and NOx formations were investigated with the experiment of combination of intake and exhaust valve timing condition. Under these various valve operating conditions, the effects of both the positive valve overlap and negative valve overlap(valve underlap) were examined simultaneously. Finally, the characteristics of cyclic THC emission were analyzed by using Fast Response FID(FR-FID) in the cylinder, intake port and exhaust port positions. Besides, the effect of the different gradients of the valve timing change on engine performance was investigated and an optimum control strategy was suggested.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.85-90
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• 2003

To control spacecraft including satellite, we should understand precisely the performance of propulsion system and the program logic with appropriate format for satellite operations. In this study, the thruster performance functions was generated by using the best curve fitting for performance data from bi-propellant thrusters. Detailed thruster performance data are, in general, company proprietary information, therefore real firing tests were performed to understand the basic characteristics of the performance curve. Experimental rocket motor utilize liquid oxygen and kerosine as propellant and designed average thrust was 100 pound.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.113-117
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• 2007

The study was performed on the development of system in which the bead width can be controlled. In order to control the bead width, we designed the automatic seam tracking device by attaching the probe type strain gauge sensor, motor driving slide and encoder to check the moving distance, and interface card connected MCU(80Cl96KC) upside the speed controllable carriage. Seam tracking experiments were done by changing the bead width. We compared and analyzed the sampling data which were obtained by output voltage of strain gauge sensor and rotary encoder pulse every 50ms.

• Structural Engineering and Mechanics
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• v.30 no.1
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• pp.1-20
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• 2008

The dynamic characteristics of the passive, semi-active, and active tuned-liquidcolumn dampers (or TLCDs) are studied in this paper. The design of the latter two are based on the first one. A water-head difference (or simply named as water head in this paper) of a passive TLCD is pre-set to form the so-called semi-active one in this paper. The pre-set of water head is released at a proper time instant during an earthquake excitation in order to enhance the vibration reduction of a structure. Two propellers are installed along a shaft inside and at the center of a passive TLCD to form an active one. These two propellers are driven by a servo-motor controlled by a computer to provide the control force. The seismic responses of a five-story shear building with a passive, semiactive, and active TLCDs are computed for demonstration and discussion. The responses of this building with a tuned mass damper (or TMD) are also included for comparison. The small-scale shaking-table experiments of a pendulum-like system with a passive or active TLCD to harmonic and seismic excitations are conducted for verification.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.992-996
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• 2004

Small electric motors in an automobile perform various tasks such as engine cooling, pumping, and in heating, ventilating, and air-conditioning (HVAC) system. At present, most of dc motors are supplied by 12V or 24V batteries. However, DC motors surfer from lack of efficiency, low life cycles and unreliability. Therefore, there is a growing interest in substituting DC motors for advanced AC motors including switched reluctance motors. Although there are several other forms SRM converters, they are either unsatisfactory to the control performance or unsuitable for the 12V-battery powered 3-phase SRM drives. Taking into account the requirement for effective operation and simplicity structure of converter in the limited internal environment of automobiles, the author inclines toward selecting the modified C-dump converter as well as the energy efficient C-dump converter. This is so that more economical and efficient converter topology in automobile industries can be utilized. This paper describes the foundation for the design and development of a 12V-250W-3000rpm SRM drives for automobiles. Furthermore, complete circuit, computer simulation and experiment results are presented to verify the performance of the C-dump converters.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.4
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• pp.377-383
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• 2002

To obtain a high performance in a direct vector controlled induction machine, it is essential to obtain the current rotor flux. The accuracy of flux observers for induction machines inherently depends on parameter sensitivity. This paper proposes an analysis method for conventional flux observers using "parameter sensitivity". The "parameter sensitivity" is defined as the ratio of the percentage change in the system transfer function to the percentage change of the parameter variation. We define the ratio between real flux and estimated no as the transfer function, and analyze a parameter sensitivity of this transfer function. Practical verification is presented to conform the capabilities of the proposed analysis method.sed analysis method.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.377-380
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• 2005

In this paper, accelerated stress test(AST) for Magnetic Switch (MS) are applied to assure specified reliability of the products. Magnetic contactor that functions with over-current relay is called MS. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. In this study, AST for product assembly are developed in order to improve the weak point so that increase the product reliability. Also we will show the basic information for the accelerated life test(ALT). The proposed AST results and procedures may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably. Finally the results of this study will contribute to improving reliability of products and strengthening competitiveness of our products in the world markets.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.536-540
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• 2002

In this paper, accelerated life test (ALT) models and procedures for Magnetic Switch (MS) are developed and applied to assure specified reliability of the products at development phase and guarantee the life of the products. Magnetic contactor that functions with over-current relay is called MS. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. In this study, ALT models for MS are developed using the relationship between stresses and life characteristics of products. Using the ALT models, we performed life tests and analyzed the tests results. The proposed ALT models and procedures may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably. Finally the results of this study will contribute to improving reliability of products and strengthening competitiveness of our products in world markets.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.2
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• pp.186-193
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• 2014

This paper presents characteristic analysis of underwater bearing for canned type electric water pump. Characteristic analysis of underwater bearing was performed using self-developed performance tester, which capable of torque change, noise change, motor speed change and abrasion loss test with respect to temperature change of underwater bearing. The performance tester can be monitored in real time by designing the control unit using the Labview program. The performance experiment was performed through comparison of the silicon carbide (SIC) and the carbon bearing. From the experiment results, performance of SIC bearing was better than carbon bearing at the abrasion and temperature experiment.