• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.10
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• pp.738-746
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• 2019

Instead of hydraulic actuation systems, an electromechanical actuation system is more efficient in terms of weight, cost, and test evaluation in the thrust vector control of the 7-ton gimbal engine used in the Korea Space Launch Vehicle-II(KSLV-II) $3^{rd}$ stage. The electromechanical actuator is a kind of servo actuator with position feedback and uses a BLDC motor that can operate at high vacuum. In the case of the gimballed rocket engine, a synthetic resonance phenomenon may occur due to a combination of a vibration mode of the actuator itself, a bending mode of the launcher structure, and an inertial load of the gimbals engine. When the synthetic resonance occurs, the control of the rocket attitude becomes unstable. Therefore, the requirements for the stiffness have been applied in consideration of the gimbal engine characteristics, the support structure, and the actuating system. For the 7-ton gimbal engine of the KSLV-II $3^{rd}$ stage, the stiffness requirement of the actuation system is $3.94{\times}10^7N/m$, and the direct drive type electromechanical actuator is designed to satisfy this requirement. In this paper, an equivalent stiffness analysis model of a direct drive electromechanical actuator designed based on the stiffness requirements is proposed and verified by experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.208-211
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• 2007

Separation Devices have two functions. These two functions are to bond and to separate two bodies. This paper is about separation devices which use explosives to separate their bodies. Explosive bolt is separated with two bodies when the explosives in the body detonated. The good things of explosive bolt are that it has simple operational system and it is made of few parts. But it has side effects; fragment and pyre-shock. To avoid these side effects gas expansion separation(GES) bolt and pressure cartridge actuation separation(PAS) devices are invented. These use pressure to separate their bodies. The pressure is generated when explosives are burned. But the sizes of PAS devices are bigger than explosive bolts. And GES bolt has a mechanically lower bonding ability than that of explosive bolt. When you design separation devices, it is recommended to know operational system and characteristics of separation devices, to design best one.

• Smart Structures and Systems
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• v.5 no.2
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• pp.139-152
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• 2009

Globally, civil infrastructures are deteriorating at an alarming rate caused by overuse, overloading, aging, damage or failure due to natural or man-made hazards. With such a vast network of deteriorating infrastructure, there is a growing interest in continuous monitoring technologies. In order to provide a true distributed sensor and control system for civil structures, we are developing a Structural Nervous System that mimics key attributes of a human nervous system. This nervous system is made up of building blocks that are designed based on mechanoreceptors as a fundamentally new approach for the development of a structural health monitoring and diagnostic system that utilizes the recently developed piezo-fibers capable of sensing and actuation. In particular, our research has been focused on producing a sensory nervous system for civil structures by using piezo-fibers as sensory receptors, nerve fibers, neuronal pools, and spinocervical tract to the nodal and central processing units. This paper presents up to date results of our research, including the design and analysis of the structural nervous system.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.610-616
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• 1997

One of the notable changes in Korean Industry in 1990's was globalization. Many of Korea plants have been built In the foreign countries and many of foreign plants have been build in Korea. And it is believed that many foreign insurance companies will begin their business in Korea soon, as Korea will open their insurance market to them. While sprinkler system plays very important role in total fire protection system, Korean sprinkler system design has not been studied in depth. Thus, it is not easy to convince the performance of Korean sprinkler system and compare it to NFPA 13, Standard for the Installation of Sprinkler System. Design guideline from both system will be listed and compared in detail. Fire water demand from both system will be reviewed to evaluate its adequacy. Water spray density and actuation time will be estimated, too.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.102-107
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• 1996

The blowdown transient pipe flows resulting from the actuation of the safety/relief valve (SRV) under valve opening conditions have been analyzed. The analytical model has been developed for a uniform pipe with friction through which the flow is discharged into a suppression pool in case of a sudden opening of the SRV The piping flow characteristics and dynamic loads are calculated. Effects of system pressure, pipe length and submergence depth are included.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.48-51
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• 1996

A 5-bar structure with redundant actuators is proposed as a finger mechanism. It is shown that one additional redundant actuator greatly enhances the load handling capacity of the system. The actuator location should be carefully decided to maximize the performance enhancement. Furthermore, we develop stiffness and frequency control algorithms based on the internal loading created by redundant actuation. The effectiveness of these algorithms have been demonstrated by simulations.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.23-26
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• 2004

Thin film is one of the most general structures used in micro-electro-mechanical systems (MEMS). To measure the mechanical properties of SU-8 film, tensile testing was adopted which offers not only elastic modulus but also yield strength and plastic deformation by load-displacement curve. Tensile testing system was constructed with linear guided servo motor for actuation, load cell for force measurement and dual microscope for strain measurement.

• Journal of KSNVE
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• v.20 no.6
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• pp.24-28
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• 2010

Many methodologies have been explored to reduce helicopter vibration. Trailing edge flaps for such a purpose have been studied for the past twenty years. A brief overview of the introduction of active vibration controls using trailing edge flaps and smart actuators is presented in series. This is the fourth article, in which a piezoelectric resonant actuation system with a buckling-beam motion amplifier for active trailing edge flaps is presented.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.845-851
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• 1986

This Paper presents micro-computer simulation programs for a pneumatic control system. The simulation programs have been written in BASIC language which is suitable for 6502CPU with 48KB memory and consist of 11 programs which describe the time response and frequency response of the pneumatic actuation system. This simulation package is stored in 51/4 inch floppy diskette. The user requires no simulation expertise on the part of designer. As the result of using this simulation programs for the pneumatic control system with stabilizing tank, it has shown that the response time of the system using air as working medium takes more time to be settled but relatively stable rather than the system using helium.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.97-104
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• 2000

Pneumatic cylinder is widely used for mechanical handling systems. Often, the impact occurs at the both ends points of pneumatic cylinder and generates destructive shock with in the structural operating members of the machine or equipment. To reduce the damage of system, therefore, shock absorbing devices are required. Cushioning of pneumatic cylinders at one or both ends of piston stroke is used to reduce the shock and vibration. The cylinder body have to withstand under high velocity and load. In this research, the pneumatic cushioning cylinder moving tests have been conducted for different load mass and supply pressure. The velocity of pneumatic cylinder actuation system with multiple orifice cushion sleeve which is set vertically controled with meter-in/out system. This study examines the dynamic characteristics of pneumatic cylinder with cushion devices. It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure. The cushion region characteristics was also revealed in the meter-in system.