• Journal of Biosystems Engineering
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• v.31 no.6 s.119
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• pp.482-488
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• 2006

Application of precision farming technology to rice cultivation could be an effective measure for rice quality improvement and environment-friendly agriculture. This study was conducted to develope a variable rate pneumatic granule applicator. Previous study reported that application uniformity of the prototype machine (C.V. = 23.3%) was not satisfactory. To improve the uniformity, increase of blow-head number from 12 to 16 was suggested. Analysis of the pneumatic conveying system showed that increase of number of blow-head was possible. Three-way variance analysis of the modified applicator showed that inserting length should be changed according to granule metering rate. The range of metering rate from 27.3 to 417.9 g/s were divided into 4 levels and 4 sets of inserting lengths were determined to ensure CV values less than 15%. The revised applicator showed satisfactory C.V. values of 9.4 to 14.6% in the metering rate. Granule conveying pattern was observed using a high speed camera and judged as the homogeneous flow pattern.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1577-1580
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• 2003

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented for its performance.

• Laser Solutions
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• v.17 no.3
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• pp.15-18
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• 2014

In this paper, we studied a machining method using a diffractive beam splitter (DBS) and multi- pulse repeated radiation for breathable film. We fabricated micro-grooves on polypropylene (PP) films using multi-pulse radiation and one-shot radiation (radiating pulses at once) and a DBS. In the result, width and depth of the PP film using multi-pulse repeated radiation were more precisely controllable. Therefore, this method can be applicable to in manufacturing breathable film precisely at a high speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1299-1302
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• 2005

Current mechanical devices are trending toward being a small size, high speedy, automation. For performing these functions, machinery elements organizing a machine should be designed exactly. Cams have high confidence and economics in ablility to transmit a motion. Accordingly, A cam mechanism is very important for processing the machine automatically. This paper introduce an inverse cam mechanism. A square shaped cam which cannot be commonly analyzed is designed and manufactured by using the NURBS interpolation algorithm. The objective of this paper is to develop a computer-aided design program. In this paper, a displacement curve of oscillating motion inverse cam mechanism with square shaped follower is analyzed. The data is redistibuted by the NURBS algorithm. A cam shape is designed by the instant velocity center method, and simulated to verify the validity of the operation state.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.111-117
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models the thermal errors for error analysis and develops an on-the-machine measurement system by which the volumetric errors are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments show that the developed system provides a high measuring accuracy, with repeatability of $\pm$2$\mu\textrm{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be also improved by using the developed measurement system when the spherical ball artifact is mounted on a modular fixture.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.231-235
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• 2013

The purpose of this paper is to compare with estimation of equivalent fatigue load in time domain and frequency domain and estimate the fatigue life of structure with multi-axial vibration loading. The fatigue analysis with two methods is implemented with various signals like random, sinusoidal signals. Also an equivalent fatigue life estimated by rainflow cycle counting in time domain is compared with results estimated with probability density function of each signal in frequency domain. In case of frequency domain, equivalent fatigue life can estimate through Dirlik's method with probability density function. And the work proposed in this paper compared the fatigue damage accumulated under uni-axial loading to that induced by multi-axial loading. The comparison is preformed for a simple cantilever beam, which is exposed to vibrations of several directions. For verification of estimation performance of fatigue life, results are compared to those of FEM analysis (ANSYS).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.930-933
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• 2005

Non-destructive inspection techniques using laser have been breading their application areas as well as growing their measurement skills together with the rapid development of circumferential technology like fiber optics. computer and image processing The ESPI technique is already on the stage of on-line testing with commercial products in developed country nations. Especially, this technique is expected to be applied to the nuclear industry, automobile and aerospace because it is proper for the vibration measurement and it can be applied to objects of a high temperature. This paper describes the use of the ESPI system for measuring vibration patterns on the reflecting objects. Using this system, high-quality Jo fringes for identifying mode shapes are displayed. A bias vibration is introduced into the reference beam to shift the Jo fringes so that fringe shift algorithms can be used to determine vibration amplitude. Using this method. amplitude fields for vibrating objects were obtained directly from the time-average interferometer recorded by the ESPI system.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.4
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• pp.9-16
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• 2011

Because of the increasing demand on the high precision and high response of a machinery, proportional control valves are widely adopted at various application fields. This paper studies on the static and dynamic characteristics of a pilot proportional pressure control valve. An experimental apparatus including hydraulic pump, variable speed inverter, pressure and flow sensors and data aquisition system was set up. And various experiments such as P-Q-V curves, step responses due to input voltage and flow rate, hysteresis, frequency response of the proportional valve was carried out and the results are discussed.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.401-404
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• 1996

A new method for the electrostatic suspension of disk-shaped objects is proposed which is based on a switched-voltage control scheme. It operates according to a relay feedback control and deploys only a single high-voltage power supply capable of delivering a dc voltage of positive and/or negative polarity. In addition to the unique feature that no high-voltage amplifiers are needed, this method provides a remarkable system simplification relative to conventional methods. It is shown that despite the inherent limit cycle property of relay feedback based control, an excellent performance in vibration suppression is attained due to the presence of a relatively large squeeze film damping. In this paper, the functional principle of the switched voltage control scheme, numerical analysis, stator electrode design, and a nonlinear dynamic model of the suspension system are described. Experimental results will be presented for a 4-inch silicon wafer that clearly reveal the capability of the proposed control structure to suspend the wafer stably at an airgap length of 50 .mu.m.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.167-174
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• 2003

Microforming technology becomes crucial in variety of industries as up-to-date machinery products and parts are miniaturized Therefore research on micro forming processes are actively conducted because of its high productivity, high precision and efficienct material usage. Since friction during microforming has greater influence than macroforming, hydrostatic pressing is much more efficient. In this paper minimization of bur during fine sheet shear forming and hydrostatic process of multi-filament extrusion to obtain fine wire of micro-order have been conducted.