This study was carried out to estimate forest biomass and to produce forest biomass thematic map for Muju county by combining field data from the 5 National Forest Inventory (2006-2007) and satellite data. For estimating forest biomass, two methods were examined using a Landsat TM-5(taken on April 28th, 2005) and field data: multi-variant regression modeling and t-Nearest Neighbor (k-NN) technique. Estimates of forest biomass by the two methods were compared by a cross-validation technique. The results showed that the two methods provide comparatively accurate estimation with similar RMSE (63.7567.26ton/ha) and mean bias (1ton/ha). However, it is concluded that the k-NN method for estimating forest biomass is superior in terms of estimation efficiency to the regression model. The total forest biomass of the study site is estimated 8.4 million ton, or 149 ton/ha by the k-NN technique.
The error motion of a machine tool spindle directly affects the surface errors of machined parts. The error motions of the spindle are not desired errors in the three linear direction motions and two rotating motions. Those are usually due to the imperfect of bearings, stiffness of spindle, assembly errors, external force or unbalance of rotors. The error motions of the spindle have been needed to be decreased to desired goal of spindle's performance. The level of error motion is needed to be estimated during the design and assembly process of the spindle. In this paper, the estimation method for the five degree of freedom (5 D.O.F) error motions of the spindle is suggested. To estimate the error motions of the spindle, waviness of shaft and bearings, external force model was used as input data. And, the estimation models are considering geometric relationship and force equilibrium of the five degree of the freedom. To calculate error motions of the spindle, not only imperfection of the shaft, bearings, such as rolling element bearing, hydrostatic bearing, and aerostatic bearing, but also driving elements such as worm, pulley, and direct driving motor systems, were considered.
This paper describes the design and evaluation procedure of an ultra-precision rotary table for freeform generating machined tools. Design of the thrust and journal hydrostatic bearings and experimental evaluation of the table were performed. To get the compact size and less lost motion direct drive servomotor with ultra precision encoder. From the considered design, following performance were confirmed by experiment. The total stiffness of the prototype rotary table was 483.6 and 97.6 for axial and radial direction, respectively. Rotational accuracy of the table was investigated by capacitive sensor and reversal measurement technique, and 0.10 radial direction and 0.05 axial direction of the rotational accuracy were confirmed. The micro resolution of the table was also investigated with displacement of capacitive sensor, and of micro resolution was confirmed. Index accuracy of the table was evaluated by the autocollimator and polygon mirror, and the arcsec accuracy and arcsec repeatability of the table were confirmed. Those are under the general requirements of ultra precision rotary tables for freeform generating machined tools.
The large surface micro machining system includes the equipments and processes for manufacturing the ultra precision micro patterned products with large surface through the mechanical machining. Recent major issue on the micro machining technology may be the development of optical parts for the back light unit of display which has the largest market. This special issue makes up with three parts; the large surface micro machining system and machine, machining process and forming process. In this paper, the state-of-the-art and core technology of large surface micro machining system is introduced with focus on the manufacturing technology for the back light unit of LCD TV. Then, some research results on the development of a roll die lathe is introduced which involves the concept of machine design, improvement of thermal characteristics in the spindle system, improvement of relative parallelism and straightness between spindle system and long stroke feed table, machining of micro pitch patterns. Finally, the direct forming process is introduced as the future work in the large surface micro machining field.
In this paper, a CMOS analog-to-digital converter (ADC) with an 8-bit 1GSPS at 1.8 V is designed. The architecture of the proposed ADC is based on a folding ADC with a cascaded-folding and an interpolation structure. A self-linearized preamplifier with source degeneration technique and a folder averaging technique for the high-performance are introduced. Further, a novel auto-switching encoder is also proposed. The chip has been fabricated with 0.18 mum 1-poly 5-metal CMOS technology. The active chip area is 0.72 mm 2 and it consumes about 200 mW at 1.8 V power supply. The simulated result of SNDR is 46.29 dB, when F in = F s /2 at F s = 1 GHz.
In this paper, for measuring the position error of the ultra precision stage more accurately, the refractive index compensation method is introduced. The wave length of the laser interferometer is compensated using the simultaneously measured the variation of room temperature in the method. In order to investigate the limit of compensation, the stationary test against two fixed reflectors mounted on the zerodur plate is performed firstly. From the experiment, it is confirmed that the measuring error of the laser interferometer can be improved from 0.34 μm to 0.11 μm by the application of the method. Secondly, for the verification of the compensating effect, it is applied to estimate the positioning accuracy of a ultra precision aerostatic stage. Two times of the refractive index compensation are performed to acquire the positioning error of the stage from the initially measured data, that is, to the initially measured positioning error and to the measured positioning error profile after the NC compensation. Although the positioning error of the aerostatic stage cannot be obtained clearly, it is known that by the compensation method, the measuring error in the laser interferometer can be improved to within 0.1 μm in the practical measurement on ultra precision stage.
The error motion of a machine tool spindle directly affects the surface errors of machined parts. Spindle motion errors such as three translational motions and two rotational motions are undesirable. These are usually due to the imperfectness of bearings, stiffness of spindle, assembly errors, and external force or unbalance of rotors. The error motions of the spindle need to be reduced for achieving the desired performance. Therefore, the level of error motion needs to be estimated during the design and assembly process of the spindle. In this study, an estimation method for five degree-of-freedom (5 DOF) error motions for a spindle with an angular contact ball bearing is suggested. To estimate the error motions of the spindle, the waviness of the inner-race of bearings and an external force model were used as input data. The estimation model considers the geometric relationship and force equilibrium of the five DOFs. To calculate the error motions of the spindle, not only the imperfections of the shaft and bearings but also driving elements such as belt pulley and direct driving motor systems are considered.
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