• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.669-681
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• 2016

Mechanical designers often make mistakes that result in unwanted over-constraints, causing difficulty in assembly operations and residual stress due to interference among parts. This study is concerned with detection and elimination of over-constraints. Screw theory is a general method that is used for constraint analysis of an assembly and motion analysis of a mechanism. Mechanical assemblies with plane-plane, pin-hole, and pin-slot constraint pairs are analyzed using screw theory to illustrate its utility. As a real-world problem, a ball valve design is analyzed using the same method, and several unwanted over-constraints are detected. Elimination measures are proposed. Nominal dimensions of some parts are adjusted, and dimensions and tolerances of the pins and holes are modified using the virtual condition boundary concept. The revised design is free of over-constraints. General procedure for applying screw theory to constraint analysis is established and demonstrated; it will contribute to improving quality of assembly designs.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.113-115
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• 2006

Consulting Stout & Snell's paper[1], design approaches for the pressurization system for a launch vehicle are introduced. We have outlined the typical system requirements and a dynamic model of the pressurization system. A brief summary on the control loop design for multiple on-off valve control systems has been also presented.

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.1019-1025
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• 2004

Pressure variation is one of the major sources on noise emission in the axial type oil piston pumps. Therefore, it is necessary that the pressure variation characteristics of the oil hydraulic piston pumps be clarified to reduce the pump noise. Pressure variations in a cylinder at the discharge region and the pump noise were simultaneously measured with discharge pressures and rotational speeds during the pump working. To investigate the effects of the pre-compression and the V-notch in the valve plate, we used the three types of valve plates. In this research, it is clear that the pressure variation characteristics of axial type oil piston pumps is deeply related to the pre-compression and to the V-notch design in valve plate. Therefore, we could reduce the pump noise by using the appropriate pre-compression angle and the notch design that are between the suction port and the discharge port in valve plate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2049-2058
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• 1992

In this work, a 6 degree of freedom lumped mass model is constructed for an OHC-type cam valve train analysis, and the model is verified experimentally. Using the verified model, an optimum cam profile is designed to minimize the maximum contact force between cam and follower under the constraints such as cam lift and cam event angle. The designed cam was carefully machined and tested experimentally. As operating the designed cam shaft on the test rig, the valve motion was precisely measured with laser displacement meter and the contact force was indirectly monitored by measuring strain at a certain point of the finger follower. Judging from the model simulation and experiment results, the maximum contact force can be reduced as much as more than 16.7 percent under maintaining the original valve flow area by adopting the optimum cam profile.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5763-5768
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• 2015

A relief valve is a mechanical element to keep safety by controlling high pressure. Usually, the high pressure is relieved by using the spring force and letting the fluid to flow from another way out of system. When its normal pressure is reached, the relief valve can return to initial state. The relief valve should be designed for smooth operation and should satisfy the structural safety requirement under operating condition. The commercial software ANSYS/WORKBENCH is utilized for flow and structural analysis. Very high pressure may cause structural problem due to severe stress. The study suggests the design satisfying the structural design requirement

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.805-815
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• 2001

Glaucoma is an eye disease which is caused by abnormal high IOP (Intra Ocular Pressure). High IOP is caused by the aqueous humor which is produced consistently but not drained due to malfunction of the trabecular system which has a role of draining the aqueous humor into the venous system. Currently, there are three methods to treat glaucoma-using medicines, surgical operation, and using implant device. The first and second methods are not long acting, so the use of implants is increasing in these days in order to drain out the aqueous humor compulsory. However, though conventional implants have a capability of pressure regulation, they cannot maintain IOPs desired for different patients, and too much aqueous humor are usually drained, to cause hypotony. To solve these problems, it is needed to develop a new implant which is capable of controling the IOP actively and copes with personal difference of patients. An active glaucoma implant consists of the valve actuator, pressure sensor, controller, and power supply. In this paper, firstly, we make an analysis of the operation of a conventional implant using a bond graph and show defects and limitations of the conventional valve analytically. Secondly, we design and analyze a valve actuator considering actuation principles, resistance elements, control methods, and energy sources focused on power saving problem. Finally, using simulations the possibility of the proposed valve actuator is investigated.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.1
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• pp.82-86
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• 2016

This paper proposes a method for the immobilization of motorbike brakes in conjunction with near-field communication (NFC) technology in order to meet the increasing demand for security and convenience of motorbike drivers. We thought about the concept of wireless key, NFC security devices and automatic solenoid valve for setting the lock and unlock module. This paper propose the design and development of an innovative anti-theft alarm system for motorcycles using NFC smart devices based on RFID system, the basis of IoT and AES(advanced encryption standard) encryption Algorithm. The design concept is based on NFC communication strategy between the vehicle and owner. To do this concept, we designed motorcycle smart key system with general-purpose NFC system and the automatic solenoid valve for setting the lock and unlock module. First, we designed control unit and NFC card reader for motorcycle smart key system. Then we propose an AES encryption algorithm and prove that the motorcycle key system is controllable by showing the result of implementing and testing, after installing.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.404-408
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• 2013

In this Study, another way to accomplish the goal of meeting large steam-flow requirements is the use of multiple valves. Multiple valves can provide better control in meeting the precision pressure controller requirements. Simulation demonstrates the effectiveness of the pressure controller. The key point of this study is to precisely control the position of the control valve on the outside of the electro-hydraulic system using a special PID controller. Simulation and experiments verify the performance of the controller.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.175-178
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• 2007

Valves has been used widely in various industries. There are many purposes for valve usage in a piping system. One of them is to control the flow rate. For a design of ball valves, it is important to know the characteristics of flows inside a ball valve. In this study, the computation fluid dynamics were conducted to observe flow velocity, flow coefficient and pressure distribution using CFX 10 according to the valve angles and uniform incoming velocity.

• 연구논문집
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• s.27
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• pp.141-151
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• 1997

Recently, the importance of electro-multifunction control valve which is digital control valve is increasing day after day. This is due to the demand of that the current industrial world wants the valve having simpler control circuit and higher operation reliability. It is the PWM controlled high speed electronic valve that satisfies the damands of current industrial world. But, the PWM controlled high speed electronic valve has some non-linearity characteristics like as the delay time of switching and the pressure oscillation phenomenon. These characteristics are an obstacle for the control of high speed & high efficiency in control system. Therefore, in this study, we set the studying purpose on analysis of parameter characteristics in solenoid, and on establishment of optimum design technique in high speed solenoid.