• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.6
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• pp.1598-1603
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• 1994

A preliminary design procedure for a multi-stage axial compressor is developed, which is based on the stage-stacking method. It determines the flow coefficient which gives rise to the design conditions required such as pressure ratio, mass flow rate and rotational speed for a given specific mass flow rate at inlet to a compressor. With this flow coefficient, blade radii, every stage and compressor performance characterics such as stage pressure ratio, adiabatic efficiency etc. are calculated by stacking each stage performance characteristics. It is shown that there is an optimum number of stage which results in the maximum of compressor overall efficiency for a given specific mass flow rate at inlet to a compressor. A test design was tried for three different geometric design constraints, and comparison with a previous study shows that present procedure could be used reliably in determining the number of compressor stage in preliminary design stage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.178-183
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• 2001

A multi-stage reciprocating air compressor has many pistons and conneting rods to one crank throw, while a general engine has one connecting rod. Those make its design hard to apply balance weight design method generally using in an engine design, This study introduces a modified balance weight design method in order to calculate the unbalanced inertia properly. Vibration tests on V/W type air compressor have been conducted to prove the usefulness of design program. It is confirmed that the proposed program is applicable to design of balance weight.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.84-93
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• 1989

This paper describes some development of Computer-Aided Process Planning System for cold-forging of rotationally symmetric parts(soild shape and solid-can combined shape) produced by the presses or formers. Using the developed system, forming sequences for producing final product are generated as graphic forms and process names, preform dimensions and process parameters(load, punch pressure, die pressure) are generated as routing sheets. Konwledges for forming sequence and process parameters are extracted from process limitations, plasticity theories, handbooks, relevent refferences and empirical know-how of experts in cold forging companies. Among extracted knowldeges, general and consistent knowledges are represented as design rules and are constructed as knowledge base. The developed system provides more powerful tool for through checking the producibilities of design, conformation of appropriate forming sequences and discoveries of new possibility. The results of the developed system are in good agreement with the practical data.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.124-128
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• 1999

Since the traditional designing approach of forming processes is based on trial and error it consumes much time and needs cost to design successful processes. Today for higher marketability of products a manufacturing system is required that can reduce production time and enhance product properties greatly. In order to implement the system a computerized design-supporting tool is indispensable for the design and supply of optimized production process for high product quality in short time In this study a design supporting system is developed and implemented to ballstud die. Using the developed system the designer can rapidly produce layouts of dies for each process sequences with consistency.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.220-228
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• 1995

An optimized 4-stage 12-bit pipelined CMOS analog-to-digital converter (ADC) architecture is proposed to obtain high linearity and high yield. The ADC based on a multiplying digital-to-analog converter (MDAC) selectively employs a binary-weighted-capacitor (BWC) array in the front-end stage and a unit-capacitor (UC) array in the back-end stages to improve integral nonlinearity (INL) and differential nonlinearity (DNL) simultaneously whil maintaining high yield. A digital-domain nonlinear error calibration technique is applied in the first stage of the ADC to improve its accuracy to 12-bit level. The largest DNL error in the mid-point code of the ADC is reduced by avoiding a code-error symmetry observed in a conventional digitally calibrated ADC is reduced by avoiding a code-error symmetry observed in a conventional digitally calibrated ADC is simulated to prove the effectiveness of the proposed ADC architecture.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.3
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• pp.25-33
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• 1997

In the design of microwave multi-stage amplifiers composed of N amplifier modules, the variation of performances of amplifier as various connection length between modules has been studied. In addition, the methods, equations and conditions for the maximum gain or the most flat gain are presented. The results of sensitivity analysis for the connection length showed that the small change in phase of input, output reflection coefficients(S$_{11}$, S$_{22}$) of module itself is the most important in determination of connection length for the most flat gain. Th egain flatness of 2-module amplifier of which connection length between modules had been determined by presented methods was the best one out of performances with various arbitrary connectio lengths.s.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.91-96
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• 1999

This study is about the design and analysis ot a suspension damper for truck driver's seat to improve the ride comfort. Trucks are usually subjected to hostile driving environments. Therefore, many truck driver's seat have suspension seats to isolate the vibration from the cab floor panel. Because the vehicle suspension system can reduce the primary vibration from the ground, only low frequency vibration can be transmitted to the driver's seat. But, this low frequency vibration can be harmful to the driver. The seat damper is very critical element to improve the ride comfort for the driver. In this study, a four-stage damper is designed and analyzed for the vibration capability. The damping coefficient of this damper can lie manually controlled in response to the road and driving environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.684-689
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• 2003

When structures undergo rotating motion, their modal characteristics often vary significantly. The variations of modal characteristics are determined from their geometric shapes and their rotating angular speed. Since the modal characteristics vary during the operation of the structures, they should be carefully scrutinized. In this paper, rotating cantilever beams are chosen as design targets which need to meet some specific design requirements. The thickness and the width of the rotating beams are assumed as multi-stage spline functions and the stage values for the thickness and the width are used as design variables for the optimization problems.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.178-187
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• 1999

The Cross rolling between flat jaws, as a kind of hot forging, is the forming method to make the axisymmetric multi-step shaft by its rotation and pressure between flat jaws which move in opposite direction. The purpose of this study is to propose the optimal geometric data for shape development of the forward forming region. All data described on this paper are quantified by experiment from initial shape design to final shape development. As the result, proper geometric data are proved that lenth of the first forming area in the forward forming region is 1.5 times larger than circumference of work-piece and the progress angle changes 3 times smoothly.

• Transactions of Materials Processing
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• v.19 no.4
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• pp.242-247
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• 2010

In the multi-pass shape drawing process, it is important to design the intermediate dies for producing sound products. Up to now, the design of the intermediate dies is mainly carried out by the industrial experts based on their experience. In this study, a design program was developed to design the intermediate dies for multi-pass shape drawing process. The program was programmed by using VisualLISP. In this program the intermediate dies can be designed by using the initial material shape and the final product shape. In order to verify the effectiveness, the program was applied to design the intermediate dies of multi-pass shape drawing for producing four teeth spline and gun slide. Finally, FE analysis and shape drawing experiment were performed to verify the effectiveness of the designed intermediate dies. As a result, it was possible to produce the drawn products with the required dimensional accuracy.