통권19호
-
Analytical and experimental studies are performed to identify the longitudinal vibration characteristics of elevator system such as the natural frequencies, and the magnification factor at resonance. In the analytical study, a computer program is developed to analyze the vibration characteristics of elevator with varing rope length of elevtor, stiffenss of thimble rod spring, and excitation frequency. The shorter rope length and the stiffer thimble rod spring make the natural frequencies of elevator higer. The resonance at the first natural frequency spreads over the entire travelling range, whereas, that at the second one ranges relatively short, region. The first natural frequencies of the Gald-Star Twin Building and the Korea Trading Center Building obtained by the experiment are overall in good agreement with the analysis result..
-
Heat transfer phenomena of solidification process of the phase change material within cylindrical can is studied experimentally. N-Eicosane paraffin wax is used for phase change material and its melting temperature is 309.8 K. In order to achieve higher heat transfer rate of latent heat storage apparatus, fins in made of copper are used in the cylindrical can. If there are fins in cylindrical can, we can know that the inward latent heat energy in paraffin can be effectively transfered to cooling water than if finless.
-
To investigate design factors of dilution ventilation system, numerical analysis of air contamination flow and concentration distribution have been made, by using the low Reynolds number turbulent model. And flow visualization and measurement of particle concentration for that model also have been made. By comparing of these results we have secured the essential data for the adequate counterplan of dilution ventilation system. The results of this study are as follows: 1) Inlet should be located near the wall for the prevention of the formation of the recircula¬tion zone. 2) In case of natural exhaust, air contamination flow is driven to the far outlet from the inlet. 3) It is favorable for dilution to make turbuence as much as possible.
-
Material damage of Unifiner Change Heater: Tube used for nearly 20 years was evaluated and Mechanical tests such as tensile tests and creep-rupture tests were conducted to predict the residual life. After the investigation, any major damage or degradation was not found except the welded zone. Microstructural observation showed that most of delta-ferrite was transformed. to sigma-phase and consequently, the ductility was very much reduced. A KLA(Knife-Line Attack) crack with 60mm in length and 2.8mm in depth was found just near the welded zone, which is believed to be caused by intergranular corrosion. Creep-rupture tests, which are very essential to predict the residual life, showed that both used base and weld metals have similar results with the reference data.
-
Hot upsetting experiments were carried out on presintered steel powder preforms in the temperature range 700-
$950^{\circ}C$ to examine the hot deformation behavior. Following conclusions were drawn on the basis of the present study. -The flow stress during hot deformation is directly related to$\alpha$ -$\gamma$ phase trasformation - The flow stress of ferrite is lower than that of austenite in the moderate temperature range 800-$900^{\circ}C$ for most alloys used in the present study - Major restoration behavior during hot deformation in the ferrite range is dynamic recovery. -
As the system monitoring technology become required in order to improve the system performance and the productivity, we’ve studied to the detection for the tool wear and the tool breakage using AE sensors that is able to detection of generated high frequency stress pulse at cutting. The detection system is consist of a sensing part, a amplifier part, a signal processing part, and a analysis & output part. The moment (a rms and a kurtosis) of statistical method is used for analysis of AE singnal. The experiment are carried out in a CNC lathe. In this study, we achieved that the amplitude level of the AE signal and statistical moments was largely changed as the tool failure. The change rate of Kurtosis was especially large, but the change rate of the rms was small.
-
Cutting tool life monitoring is a critical element needed for designing unmanned machining systems. This paper describes a tool wear measurement system using computer vision which repeatedly measures flank and crater wear of a single point cutting tool. This direct tool wear measurement method is based on an interactive procedure utilizing a image processor and multi-vision sensors. A measurement software calcultes 7 parameters to characterize flank and crater wear. Performance test revealed that the computer vision technique provides precise, absolute tool-wear quantification and reduces human maesurement errors.
-
This paper presents a simple identification method of the actual kinematic parameters for the robot with parallel joints. It is known that Denavit-Hartenberg's coordinate system is not useful for nearly parallel joints. In this paper, the coordinate frames are reassigned to model the kinematic parameter between nearly parallel joints by four parameters. The proposed identification method uses a straight ruler about 1m long. A robot hand is placed by using a teaching pendant at the prescribed points on the ruler, and corresponding error function is defined. The identified kinematic parameters which make the error function zero are obtained by iterative least square error method based on the singular value decomposition. In the compensation of joint angles, only the position is considered because the usual applications of robot do not require a precise orientation control.
-
Cerebellar Model Arithmetic Controller(CMAC) has been introduced as an adaptive control function generator. CMAC computes control functions referring to a distributed memory table storing functional values rather than by solving equations analytically or numerically. CMAC has a unique mapping structure as a coarse coding and supervisory delta-rule learning property. In this paper, learning aspects and a convergence of the CMAC were investigated. The efficient training algorithms were developed to overcome the limitations caused by the conventional maximum error correction training and to eliminate the accumulated learning error caused by a sequential node training. A nonlinear function generator and a motion generator for a two d. o. f. manipulator were simulated. The efficiency of the various learning algorithms was demonstrated through the cpu time used and the convergence of the rms and maximum errors accumulated during a learning process; A generalization property and a learning effect due to the various gains were simulated. A uniform quantizing method was applied to cope with various ranges of input variables efficiently.
-
This study is to develop interactive program for work-cell layout of SACARA type robot by using PC. To make this program interactively, we made use of the software which has the function of menu, dialog box, and graphic. By using the mouse, we can progress this program quickly and easily. It has 2Y2 dimension and provides that one can layout elements (robot, peripheral device, and etc.), create work path, and calculate cycle time of working robot. By comparing with cycle times of any number of work-cell layout for same work, we can evaluate work-cell layout. Finally, we can select one work-cell layout to be considered optimal one which has the least cycle time.
-
As an adaptive control function generator, the CMAC (Cerebellar Model Arithmetic or Articulated Controller) based learning control has drawn a great attention to realize a rather robust real-time manipulator control under the various uncertainties. There remain, however, inherent problems to be solved in the CMAC application to robot motion control or perception of sensory information. To apply the CMAC to the various unmodeled or modeled systems more efficiently, it is necessary to analyze the effects of the CMAC control parameters on the trained net. Although the CMAC control parameters such as size of the quantizing block, learning gain, input offset, and ranges of input variables play a key role in the learning performance and system memory requirement, these have not been fully investigated yet. These parameters should be determined, of course, considering the shape of the desired function to be trained and learning algorithms applied. In this paper, the interrelation of these parameters with learning performance is investigated under the basic learning schemes presented by authors. Since an analytic approach only seems to be very difficult and even impossible for this purpose, various simulations have been performed with pre specified functions and their results were analyzed. A general step following design guide was set up according to the various simulation results.
-
Using monochrome CCD camera with high speed electronic shutter. blade image is captured in the environment with vibration. The image is preprocessed using LoG filter and zero crossing. We used Hough transformation method to detect straight lines and obtained width between lines caused by grinders. This paper proposes automatic blade measuring method to automate the process control of blade grinding.
-
Generally Cam-Follower systems consist of two elements: Cam is for rotating motion and follower for reciprocating motion. Depending on the shape of cam and type of follower, the motion of cam-follower system is determined. Thus design process and analysis process must be well defined. The design process means to find the coordinates of cam shape which can be defined the given motion of follower and the analysis process means to determine the motion curve of follower corresponding to the given cam based on the dimensions of a cam-follower system. This paper consists of two parts: One is development of a numerical method for design and analysis of cam-follower systems, the other is for development of a CAD program and its application. As the first part of the paper, an iterative contact method is proposed. This method can calculate the contact points between cam and roller and determine their contact angles iteratively. The second part of the paper presents the structure of a CAD program and its availability to the industrial applications.
-
Generally cam-follower systems consist of two elements: Cam is for rotating motion and follower for reciprocating motion. Depending on the shape of cam and type of follower, the motion of cam-follower system is determined. Thus design process and analysis process must be well defined. The design process means to find the coordinates of cam shape which can be defined the given motion of follower and the analysis process means to determine the motion curve of follower corresponding to the given cam based on the dimensions of a cam-follower system. This paper consists of two parts : One is for development of a numerical method for design and analysis of cam-follower systems, the other is for development of a CAD program and its application. As the second part of the paper, the structure of a CAD program is introduced. Four data files are used in the program where the design process and the analysis process are carried out interactively to en hence its availability to the industrial applications. The first part of the paper 'presents the iterative contact method which can determine the contact points and their angles between cam and roller.
-
Many computer programs are being developed to aid the design of physical models. These efforts highlight the importance of computer model of three dimensional object. In this paper a CAD application program is introduced which can be implemented to modeling some part that composed with 3 types of surface form ; free form surface, fillt surface, surface of revolution, and a geometry description language which can represent a shape efficiently is preseneted.
-
The automation of textile machinery in the fabric manufacture is strongly demanded in order to improve the industrial structure related to labour-force and cost curtailment, in addition, to keep step with the various and small production system and the consumption tendency requesting a high quality fabrics. In this thesis, the technology applying the computer to an air jet loom and characteristics obtained from it are derived. To efficently apply an automized and unmanned textile machinery, an air jet loom is equipped with the let-off, take-up and weft insertion device attached a central processing unit(CPU) which can automatically operate according to a program. As a result, an air jet loom is available for the factory automation, which has advantages including productivity promotion, high quality security, energy savings, specification & variety, efficient production control, in fabric manufacturing process.